Science.gov

Sample records for affecting arctic climate

  1. Is climate change affecting wolf populations in the high Arctic?

    USGS Publications Warehouse

    Mech, L.D.

    2004-01-01

    Global climate change may affect wolves in Canada's High Arctic (80DG N) acting through three trophic levels (vegetation, herbivores, and wolves). A wolf pack dependent on muskoxen and arctic hares in the Eureka area of Ellesmere Island denned and produced pups most years from at least 1986 through 1997. However when summer snow covered vegetation in 1997 and 2000 for the first time since records were kept, halving the herbivore nutrition-replenishment period, muskox and hare numbers dropped drastically, and the area stopped supporting denning wolves through 2003. The unusual weather triggering these events was consistent with global-climate-change phenomena.

  2. Is climate change affecting wolf populations in the high Arctic?

    USGS Publications Warehouse

    Mech, L.D.

    2004-01-01

    Gobal climate change may affect wolves in Canada's High Arctic (80?? N) acting through three trophic levels (vegetation, herbivores, and wolves). A wolf pack dependent on muskoxen and arctic hares in the Eureka area of Ellesmere Island denned and produced pups most years from at least 1986 through 1997. However, when summer snow covered vegetation in 1997 and 2000 for the first time since records were kept, halving the herbivore nutrition-replenishment period, muskox and hare numbers dropped drastically, and the area stopped supporting denning wolves through 2003. The unusual weather triggering these events was consistent with global-climate-change phenomena. ?? 2004 Kluwer Academic Publishers.

  3. Can Ice-Nucleating Aerosols Affect Arctic Seasonal Climate?

    SciTech Connect

    Prenni, Anthony J.; Harrington, Jerry Y.; Tjernstrom, Michael; DeMott, Paul J.; Avramov, Alexander; Long, Charles N.; Kreidenweis, Sonia M.; Olsson, Peter Q.; Verlinde, J.

    2007-04-01

    To date, climate and regional models have generally proven unsuccessful at simulating Arctic cloudiness, particularly during the colder months. Models tend to underpredict the amount of liquid water in mixed-phase clouds, which are ubiquitous in this region. This is problematic because cloud coverage and phase can greatly impact the Arctic radiative budget. Using recent measurements of ice nucleating aerosol, we show that incorrect, or nonexistent, parameterizations of aerosol-cloud interactions are at least partially responsible for the poor model predictions. Moreover, we show that this can lead to errors in the modeled surface radiative energy budget of 10-100 W m-2.

  4. Seasonal climate forecasts significantly affected by observational uncertainty of Arctic sea ice concentration

    NASA Astrophysics Data System (ADS)

    Bunzel, Felix; Notz, Dirk; Baehr, Johanna; Müller, Wolfgang A.; Fröhlich, Kristina

    2016-01-01

    We investigate how observational uncertainty in satellite-retrieved sea ice concentrations affects seasonal climate predictions. To do so, we initialize hindcast simulations with the Max Planck Institute Earth System Model every 1 May and 1 November from 1981 to 2011 with two different sea ice concentration data sets, one based on the NASA Team and one on the Bootstrap algorithm. For hindcasts started in November, initial differences in Arctic sea ice area and surface temperature decrease rapidly throughout the freezing period. For hindcasts started in May, initial differences in sea ice area increase over time. By the end of the melting period, this causes significant differences in 2 meter air temperature of regionally more than 3°C. Hindcast skill for surface temperatures over Europe and North America is higher with Bootstrap initialization during summer and with NASA Team initialization during winter. This implies that the observational uncertainty also affects forecasts of teleconnections that depend on northern hemispheric climate indices.

  5. Arctic climate tipping points.

    PubMed

    Lenton, Timothy M

    2012-02-01

    There is widespread concern that anthropogenic global warming will trigger Arctic climate tipping points. The Arctic has a long history of natural, abrupt climate changes, which together with current observations and model projections, can help us to identify which parts of the Arctic climate system might pass future tipping points. Here the climate tipping points are defined, noting that not all of them involve bifurcations leading to irreversible change. Past abrupt climate changes in the Arctic are briefly reviewed. Then, the current behaviour of a range of Arctic systems is summarised. Looking ahead, a range of potential tipping phenomena are described. This leads to a revised and expanded list of potential Arctic climate tipping elements, whose likelihood is assessed, in terms of how much warming will be required to tip them. Finally, the available responses are considered, especially the prospects for avoiding Arctic climate tipping points. PMID:22270703

  6. Observational uncertainty of Arctic sea-ice concentration significantly affects seasonal climate forecasts

    NASA Astrophysics Data System (ADS)

    Bunzel, Felix; Notz, Dirk; Baehr, Johanna; Müller, Wolfgang; Fröhlich, Kristina

    2016-04-01

    We examine how the choice of a particular satellite-retrieved sea-ice concentration dataset used for initialising seasonal climate forecasts impacts the prediction skill of Arctic sea-ice area and Northern hemispheric 2-meter air temperatures. To do so, we performed two assimilation runs with the Max Planck Institute Earth System Model (MPI-ESM) from 1979 to 2012, where atmospheric and oceanic parameters as well as sea-ice concentration were assimilated using Newtonian relaxation. The two assimilation runs differ only in the sea-ice concentration dataset used for assimilating sea ice. In the first run, we use sea-ice concentrations as derived by the NASA-Team algorithm, while in the second run we use sea-ice concentrations as derived from the Bootstrap algorithm. A major difference between these two sea-ice concentration data products involves the treatment of melt ponds. While for both products melt ponds appear as open water in the raw satellite data, the Bootstrap algorithm more strongly attempts to offset this systematic bias by synthetically increasing the retrieved ice concentration during summer months. For each year of the two assimilation runs we performed a 10-member ensemble of hindcast experiments starting on 1 May and 1 November with a hindcast length of 6 months. For hindcasts started in November, initial differences in Arctic sea-ice area and surface temperature decrease rapidly throughout the freezing period. For hindcasts started in May, initial sea-ice area differences increase over time. By the end of the melting period, this causes significant differences in 2-meter air temperature of regionally more than 3°C. Hindcast skill for surface temperatures over Europe and North America is higher with Bootstrap initialization during summer and with NASA Team initialisation during winter. This implies that the choice of the sea-ice data product and, thus, the observational uncertainty also affects forecasts of teleconnections that depend on Northern

  7. Time varying arctic climate change amplification

    SciTech Connect

    Chylek, Petr; Dubey, Manvendra K; Lesins, Glen; Wang, Muyin

    2009-01-01

    During the past 130 years the global mean surface air temperature has risen by about 0.75 K. Due to feedbacks -- including the snow/ice albedo feedback -- the warming in the Arctic is expected to proceed at a faster rate than the global average. Climate model simulations suggest that this Arctic amplification produces warming that is two to three times larger than the global mean. Understanding the Arctic amplification is essential for projections of future Arctic climate including sea ice extent and melting of the Greenland ice sheet. We use the temperature records from the Arctic stations to show that (a) the Arctic amplification is larger at latitudes above 700 N compared to those within 64-70oN belt, and that, surprisingly; (b) the ratio of the Arctic to global rate of temperature change is not constant but varies on the decadal timescale. This time dependence will affect future projections of climate changes in the Arctic.

  8. Impacts of a Warming Arctic - Arctic Climate Impact Assessment

    NASA Astrophysics Data System (ADS)

    Arctic Climate Impact Assessment

    2004-12-01

    The Arctic is now experiencing some of the most rapid and severe climate change on earth. Over the next 100 years, climate change is expected to accelerate, contributing to major physical, ecological, social, and economic changes, many of which have already begun. Changes in arctic climate will also affect the rest of the world through increased global warming and rising sea levels. Impacts of a Warming Arctic is a plain language synthesis of the key findings of the Arctic Climate Impact Assessment (ACIA), designed to be accessible to policymakers and the broader public. The ACIA is a comprehensively researched, fully referenced, and independently reviewed evaluation of arctic climate change. It has involved an international effort by hundreds of scientists. This report provides vital information to society as it contemplates its responses to one of the greatest challenges of our time. It is illustrated in full color throughout.

  9. Changes in forcing factors affecting coastal and shallow water erosion in the future Arctic climate change projections.

    NASA Astrophysics Data System (ADS)

    Dobrynin, Mikhail; Razumov, Sergey; Brovkin, Victor; Ilyina, Tatiana; Grigoriev, Mikhail

    2016-04-01

    Driving factors of seabed and coastal erosion in the Arctic can be classified as thermal and mechanical. Thermal factors such as air and ocean temperatures affect the seabed and coastal ground temperatures. Mechanical factors such as ocean currents and surface gravity waves contribute to the seabed and costal erosion due to shear stress. Due to polar amplification, the Arctic experiences strong increase in air and water temperature, sea-ice loss and changes in the ocean and atmospheric circulation, temperature and wind distribution. These climatic changes lead to changes in factors driving seabed and coastal erosion, which is expected to accelerate in the shallow Arctic regions such as the Laptev sea and East Siberian sea. In these regions, the coastal line to a large extent consists of frozen rocks, sediments and organic soils including ground ice. The increase of erosion rate of the coastal line will increase the release of organic and inorganic matter from thawed permafrost. Dynamics of thermal and mechanical drivers of seabed and coastal erosion in the present and future climate change (RCP8.5 scenario) simulated by the CMIP5 version of the MPI Earth system model and wave model WAM will be presented. Special attention will be given to changes in the air temperature, wind dynamics and development of new waves system in the ``ice-free'' Arctic and its role in the seabed and coastal erosion.

  10. Arctic Climate Systems Analysis

    SciTech Connect

    Ivey, Mark D.; Robinson, David G.; Boslough, Mark B.; Backus, George A.; Peterson, Kara J.; van Bloemen Waanders, Bart G.; Swiler, Laura Painton; Desilets, Darin Maurice; Reinert, Rhonda Karen

    2015-03-01

    This study began with a challenge from program area managers at Sandia National Laboratories to technical staff in the energy, climate, and infrastructure security areas: apply a systems-level perspective to existing science and technology program areas in order to determine technology gaps, identify new technical capabilities at Sandia that could be applied to these areas, and identify opportunities for innovation. The Arctic was selected as one of these areas for systems level analyses, and this report documents the results. In this study, an emphasis was placed on the arctic atmosphere since Sandia has been active in atmospheric research in the Arctic since 1997. This study begins with a discussion of the challenges and benefits of analyzing the Arctic as a system. It goes on to discuss current and future needs of the defense, scientific, energy, and intelligence communities for more comprehensive data products related to the Arctic; assess the current state of atmospheric measurement resources available for the Arctic; and explain how the capabilities at Sandia National Laboratories can be used to address the identified technological, data, and modeling needs of the defense, scientific, energy, and intelligence communities for Arctic support.

  11. Continuous and discrete extreme climatic events affecting the dynamics of a high-arctic reindeer population.

    PubMed

    Chan, Kung-Sik; Mysterud, Atle; Øritsland, Nils Are; Severinsen, Torbjørn; Stenseth, Nils Chr

    2005-10-01

    Climate at northern latitudes are currently changing both with regard to the mean and the temporal variability at any given site, increasing the frequency of extreme events such as cold and warm spells. Here we use a conceptually new modelling approach with two different dynamic terms of the climatic effects on a Svalbard reindeer population (the Brøggerhalvøya population) which underwent an extreme icing event ("locked pastures") with 80% reduction in population size during one winter (1993/94). One term captures the continuous and linear effect depending upon the Arctic Oscillation and another the discrete (rare) "event" process. The introduction of an "event" parameter describing the discrete extreme winter resulted in a more parsimonious model. Such an approach may be useful in strongly age-structured ungulate populations, with young and very old individuals being particularly prone to mortality factors during adverse conditions (resulting in a population structure that differs before and after extreme climatic events). A simulation study demonstrates that our approach is able to properly detect the ecological effects of such extreme climate events. PMID:16010537

  12. How does climate change influence Arctic mercury?

    PubMed

    Stern, Gary A; Macdonald, Robie W; Outridge, Peter M; Wilson, Simon; Chételat, John; Cole, Amanda; Hintelmann, Holger; Loseto, Lisa L; Steffen, Alexandra; Wang, Feiyue; Zdanowicz, Christian

    2012-01-01

    Recent studies have shown that climate change is already having significant impacts on many aspects of transport pathways, speciation and cycling of mercury within Arctic ecosystems. For example, the extensive loss of sea-ice in the Arctic Ocean and the concurrent shift from greater proportions of perennial to annual types have been shown to promote changes in primary productivity, shift foodweb structures, alter mercury methylation and demethylation rates, and influence mercury distribution and transport across the ocean-sea-ice-atmosphere interface (bottom-up processes). In addition, changes in animal social behavior associated with changing sea-ice regimes can affect dietary exposure to mercury (top-down processes). In this review, we address these and other possible ramifications of climate variability on mercury cycling, processes and exposure by applying recent literature to the following nine questions; 1) What impact has climate change had on Arctic physical characteristics and processes? 2) How do rising temperatures affect atmospheric mercury chemistry? 3) Will a decrease in sea-ice coverage have an impact on the amount of atmospheric mercury deposited to or emitted from the Arctic Ocean, and if so, how? 4) Does climate affect air-surface mercury flux, and riverine mercury fluxes, in Arctic freshwater and terrestrial systems, and if so, how? 5) How does climate change affect mercury methylation/demethylation in different compartments in the Arctic Ocean and freshwater systems? 6) How will climate change alter the structure and dynamics of freshwater food webs, and thereby affect the bioaccumulation of mercury? 7) How will climate change alter the structure and dynamics of marine food webs, and thereby affect the bioaccumulation of marine mercury? 8) What are the likely mercury emissions from melting glaciers and thawing permafrost under climate change scenarios? and 9) What can be learned from current mass balance inventories of mercury in the Arctic? The

  13. The Arctic's Role in Climate.

    ERIC Educational Resources Information Center

    Baker, D. James

    1986-01-01

    Discusses the special role the Arctic region plays in climate, focusing on: (1) the global energy balance; (2) feedback mechanisms; (3) effects of increasing carbon dioxide; and (4) climate processes study programs. (JN)

  14. Factors affecting projected Arctic surface shortwave heating and albedo change in coupled climate models.

    PubMed

    Holland, Marika M; Landrum, Laura

    2015-07-13

    We use a large ensemble of simulations from the Community Earth System Model to quantify simulated changes in the twentieth and twenty-first century Arctic surface shortwave heating associated with changing incoming solar radiation and changing ice conditions. For increases in shortwave absorption associated with albedo reductions, the relative influence of changing sea ice surface properties and changing sea ice areal coverage is assessed. Changes in the surface sea ice properties are associated with an earlier melt season onset, a longer snow-free season and enhanced surface ponding. Because many of these changes occur during peak solar insolation, they have a considerable influence on Arctic surface shortwave heating that is comparable to the influence of ice area loss in the early twenty-first century. As ice area loss continues through the twenty-first century, it overwhelms the influence of changes in the sea ice surface state, and is responsible for a majority of the net shortwave increases by the mid-twenty-first century. A comparison with the Arctic surface albedo and shortwave heating in CMIP5 models indicates a large spread in projected twenty-first century change. This is in part related to different ice loss rates among the models and different representations of the late twentieth century ice albedo and associated sea ice surface state. PMID:26032318

  15. Factors affecting projected Arctic surface shortwave heating and albedo change in coupled climate models

    PubMed Central

    Holland, Marika M.; Landrum, Laura

    2015-01-01

    We use a large ensemble of simulations from the Community Earth System Model to quantify simulated changes in the twentieth and twenty-first century Arctic surface shortwave heating associated with changing incoming solar radiation and changing ice conditions. For increases in shortwave absorption associated with albedo reductions, the relative influence of changing sea ice surface properties and changing sea ice areal coverage is assessed. Changes in the surface sea ice properties are associated with an earlier melt season onset, a longer snow-free season and enhanced surface ponding. Because many of these changes occur during peak solar insolation, they have a considerable influence on Arctic surface shortwave heating that is comparable to the influence of ice area loss in the early twenty-first century. As ice area loss continues through the twenty-first century, it overwhelms the influence of changes in the sea ice surface state, and is responsible for a majority of the net shortwave increases by the mid-twenty-first century. A comparison with the Arctic surface albedo and shortwave heating in CMIP5 models indicates a large spread in projected twenty-first century change. This is in part related to different ice loss rates among the models and different representations of the late twentieth century ice albedo and associated sea ice surface state. PMID:26032318

  16. Occurrence of near-surface ozone depletion in the Arctic spring strongly affected by Northern-Hemispheric climate variability

    NASA Astrophysics Data System (ADS)

    Koo, J.; Wang, Y.; Jiang, T.; Deng, Y.; Oltmans, S. J.; Solberg, S.

    2013-12-01

    In the Arctic spring, near-surface ozone can decrease to extremely low levels due to chemical removal catalyzed by halogen radicals. These ozone depletion events (ODEs) are usually accompanied by greatly enhanced surface deposition of reactive gaseous mercury. Here we show the effects of regional climate variability on Arctic ODE frequencies by analyzing surface ozone measurements at three monitoring sites (Barrow, Alert, and Zeppelinfjellet) in the past 30 years. Among the various climate variability indices, the Western Pacific (WP) index has the most significant impact. In years with high ODE frequencies at Barrow and Alert in April, the WP teleconnection pattern tends to be in its negative phase with a weakened storm track from the western Pacific to the Arctic and a strengthened subtropical jet across the Pacific, reducing transport of ozone-rich air masses from mid-latitudes to the Arctic. Analysis of the observations at Zeppelinfjellet indicates a much stronger influence of WP pattern in the 2000s than 1990s. Consequently, the WP index may be used as a proxy to assess ODE frequencies and subsequent environmental impacts in future climate projections.

  17. Climate change and Arctic parasites.

    PubMed

    Dobson, Andy; Molnár, Péter K; Kutz, Susan

    2015-05-01

    Climate is changing rapidly in the Arctic. This has important implications for parasites of Arctic ungulates, and hence for the welfare of Arctic peoples who depend on caribou, reindeer, and muskoxen for food, income, and a focus for cultural activities. In this Opinion article we briefly review recent work on the development of predictive models for the impacts of climate change on helminth parasites and other pathogens of Arctic wildlife, in the hope that such models may eventually allow proactive mitigation and conservation strategies. We describe models that have been developed using the metabolic theory of ecology. The main strength of these models is that they can be easily parameterized using basic information about the physical size of the parasite. Initial results suggest they provide important new insights that are likely to generalize to a range of host-parasite systems. PMID:25900882

  18. The Arctic Grand Challenge: Abrupt Climate Change

    NASA Astrophysics Data System (ADS)

    Wilkniss, P. E.

    2003-12-01

    Trouble in polar paradise (Science, 08/30/02), significant changes in the Arctic environment are scientifically documented (R.E. Moritz et al. ibid.). More trouble, lots more, "abrupt climate change," (R. B. Alley, et al. Science 03/28/03). R. Corell, Arctic Climate Impact Assessment team (ACIA), "If you want to see what will happen in the rest of the world 25 years from now just look what's happening in the Arctic," (Arctic Council meeting, Iceland, 08/03). What to do? Make abrupt Arctic climate change a grand challenge for the IPY-4 and beyond! Scientifically:Describe the "state" of the Arctic climate system as succinctly as possible and accept it as the point of departure.Develop a hypothesis and criteria what constitutes "abrupt climate change," in the Arctic that can be tested with observations. Observations: Bring to bear existing observations and coordinate new investments in observations through an IPY-4 scientific management committee. Make the new Barrow, Alaska, Global Climate Change Research Facility a major U.S. contribution and focal point for the IPY-4 in the U.S Arctic. Arctic populations, Native peoples: The people of the North are living already, daily, with wrenching change, encroaching on their habitats and cultures. For them "the earth is faster now," (I. Krupnik and D. Jolly, ARCUS, 2002). From a political, economic, social and entirely realistic perspective, an Arctic grand challenge without the total integration of the Native peoples in this effort cannot succeed. Therefore: Communications must be established, and the respective Native entities must be approached with the determination to create well founded, well functioning, enduring partnerships. In the U.S. Arctic, Barrow with its long history of involvement and active support of science and with the new global climate change research facility should be the focal point of choice Private industry: Resource extraction in the Arctic followed by oil and gas consumption, return the combustion

  19. Climate-derived tensions in Arctic security.

    SciTech Connect

    Backus, George A.; Strickland, James Hassler

    2008-09-01

    Globally, there is no lack of security threats. Many of them demand priority engagement and there can never be adequate resources to address all threats. In this context, climate is just another aspect of global security and the Arctic just another region. In light of physical and budgetary constraints, new security needs must be integrated and prioritized with existing ones. This discussion approaches the security impacts of climate from that perspective, starting with the broad security picture and establishing how climate may affect it. This method provides a different view from one that starts with climate and projects it, in isolation, as the source of a hypothetical security burden. That said, the Arctic does appear to present high-priority security challenges. Uncertainty in the timing of an ice-free Arctic affects how quickly it will become a security priority. Uncertainty in the emergent extreme and variable weather conditions will determine the difficulty (cost) of maintaining adequate security (order) in the area. The resolution of sovereignty boundaries affects the ability to enforce security measures, and the U.S. will most probably need a military presence to back-up negotiated sovereignty agreements. Without additional global warming, technology already allows the Arctic to become a strategic link in the global supply chain, possibly with northern Russia as its main hub. Additionally, the multinational corporations reaping the economic bounty may affect security tensions more than nation-states themselves. Countries will depend ever more heavily on the global supply chains. China has particular needs to protect its trade flows. In matters of security, nation-state and multinational-corporate interests will become heavily intertwined.

  20. Arctic Cities and Climate Change: A Geographic Impact Assessment

    NASA Astrophysics Data System (ADS)

    Shiklomanov, N. I.; Streletskiy, D. A.

    2014-12-01

    Arctic climate change is a concern for the engineering community, land-use planners and policy makers as it may have significant impacts on socio-economic development and human activities in the northern regions. A warmer climate has potential for a series of positive economic effects, such as development of maritime transportation, enhanced agricultural production and decrease in energy consumption. However, these potential benefits may be outwaited by negative impacts related to transportation accessibility and stability of existing infrastructure, especially in permafrost regions. Compared with the Arctic zones of other countries, the Russian Arctic is characterized by higher population, greater industrial development and urbanization. Arctic urban areas and associated industrial sites are the location of some of intense interaction between man and nature. However, while there is considerable research on various aspects of Arctic climate change impacts on human society, few address effects on Arctic cities and their related industries. This presentation overviews potential climate-change impacts on Russian urban environments in the Arctic and discusses methodology for addressing complex interactions between climatic, permafrost and socio-economic systems at the range of geographical scales. We also provide a geographic assessment of selected positive and negative climate change impacts affecting several diverse Russian Arctic cities.

  1. The changing seasonal climate in the Arctic.

    PubMed

    Bintanja, R; van der Linden, E C

    2013-01-01

    Ongoing and projected greenhouse warming clearly manifests itself in the Arctic regions, which warm faster than any other part of the world. One of the key features of amplified Arctic warming concerns Arctic winter warming (AWW), which exceeds summer warming by at least a factor of 4. Here we use observation-driven reanalyses and state-of-the-art climate models in a variety of standardised climate change simulations to show that AWW is strongly linked to winter sea ice retreat through the associated release of surplus ocean heat gained in summer through the ice-albedo feedback (~25%), and to infrared radiation feedbacks (~75%). Arctic summer warming is surprisingly modest, even after summer sea ice has completely disappeared. Quantifying the seasonally varying changes in Arctic temperature and sea ice and the associated feedbacks helps to more accurately quantify the likelihood of Arctic's climate changes, and to assess their impact on local ecosystems and socio-economic activities. PMID:23532038

  2. The changing seasonal climate in the Arctic

    PubMed Central

    Bintanja, R.; van der Linden, E. C.

    2013-01-01

    Ongoing and projected greenhouse warming clearly manifests itself in the Arctic regions, which warm faster than any other part of the world. One of the key features of amplified Arctic warming concerns Arctic winter warming (AWW), which exceeds summer warming by at least a factor of 4. Here we use observation-driven reanalyses and state-of-the-art climate models in a variety of standardised climate change simulations to show that AWW is strongly linked to winter sea ice retreat through the associated release of surplus ocean heat gained in summer through the ice-albedo feedback (~25%), and to infrared radiation feedbacks (~75%). Arctic summer warming is surprisingly modest, even after summer sea ice has completely disappeared. Quantifying the seasonally varying changes in Arctic temperature and sea ice and the associated feedbacks helps to more accurately quantify the likelihood of Arctic's climate changes, and to assess their impact on local ecosystems and socio-economic activities. PMID:23532038

  3. Progress in Understanding the Arctic Climate System

    NASA Astrophysics Data System (ADS)

    Fichefet, Thierry; Dick, Chad; Flato, Greg; Kane, Douglas; Moore, Jim

    2004-04-01

    The Arctic region is where numerical climate models generally predict the largest warming under the influence of increased greenhouse gas concentrations. It is also the area where discrepancies between predictions are greatest. Arctic processes seem to be crucial for maintaining the oceanic meridional overturning circulation (MOC), and some models suggest that global warming might freshen the Arctic Ocean and peripheral seas to the extent that this circulation collapses. Should that happen, parts of the North Atlantic region might cool rather than warm over the next 100 years. So, what are the global consequences of natural or human-induced changes in the Arctic climate system? Is the Arctic climate system really as sensitive to enhanced greenhouse gas concentrations as climate models suggest?

  4. Identifying uncertainties in Arctic climate change projections

    NASA Astrophysics Data System (ADS)

    Hodson, Daniel L. R.; Keeley, Sarah P. E.; West, Alex; Ridley, Jeff; Hawkins, Ed; Hewitt, Helene T.

    2013-06-01

    Wide ranging climate changes are expected in the Arctic by the end of the 21st century, but projections of the size of these changes vary widely across current global climate models. This variation represents a large source of uncertainty in our understanding of the evolution of Arctic climate. Here we systematically quantify and assess the model uncertainty in Arctic climate changes in two CO2 doubling experiments: a multimodel ensemble (CMIP3) and an ensemble constructed using a single model (HadCM3) with multiple parameter perturbations (THC-QUMP). These two ensembles allow us to assess the contribution that both structural and parameter variations across models make to the total uncertainty and to begin to attribute sources of uncertainty in projected changes. We find that parameter uncertainty is an major source of uncertainty in certain aspects of Arctic climate. But also that uncertainties in the mean climate state in the 20th century, most notably in the northward Atlantic ocean heat transport and Arctic sea ice volume, are a significant source of uncertainty for projections of future Arctic change. We suggest that better observational constraints on these quantities will lead to significant improvements in the precision of projections of future Arctic climate change.

  5. On Prediction and Predictability of the Arctic Climate System

    NASA Astrophysics Data System (ADS)

    Maslowski, W.; Clement Kinney, J.; Roberts, A.; Higgins, M.; Osinski, R.; Cassano, J. J.; Craig, A.; Gutowski, W. J.; Lettenmaier, D. P.; Lipscomb, W. H.; Tulaczyk, S. M.; Zeng, X.

    2012-12-01

    Arctic sea ice is a key indicator of the state of Earth's climate because of both its sensitivity to warming and its role in amplifying climate change. However, the current system-level understanding and representation of critical arctic processes and feedbacks in state-of-the-art Earth System Models (EaSMs) is still inadequate. This becomes increasingly critical as the perennial and total summer sea ice cover continues its accelerated decline that started in the late 1990s. Growing evidence suggests that the shrinking Arctic ice pack affects pan-Arctic atmospheric and oceanic circulation, snow cover, the Greenland ice sheet, permafrost and vegetation. Such changes could have significant ramifications for global sea level, the global surface energy and moisture budget, atmospheric and oceanic circulations, geosphere-biosphere feedbacks, as well as affecting native coastal communities, and international commerce. We evaluate available results from CMIP5 models against limited observations for their skill in representing recent decadal variability of Arctic sea ice area, thickness, drift and export. We also intercompare results from CMIP5 models with selected CMIP3 models and a hierarchy of regional ice-ocean and fully coupled climate models to demonstrate possible gains or outstanding limitations in representing past and present climate variability in the Arctic. Some of the limitations we have diagnosed in the CMIP3 family of models include: northward oceanic heat fluxes and their interface with the atmosphere, distribution of sea ice area and thickness, variability of sea ice volume in the Arctic Ocean, and freshwater (both solid and liquid) export into the North Atlantic. We argue that the ability of global models to realistically reproduce the above processes affecting recent warming and sea ice melt in the Arctic Ocean distorts predictability of EaSMs and limits the accuracy of their future arctic and global climate predictions. To better understand the past

  6. Changes to freshwater systems affecting Arctic infrastructure and natural resources

    NASA Astrophysics Data System (ADS)

    Instanes, Arne; Kokorev, Vasily; Janowicz, Richard; Bruland, Oddbjørn; Sand, Knut; Prowse, Terry

    2016-03-01

    The resources component of the Arctic Freshwater Synthesis focuses on the potential impact of future climate and change on water resources in the Arctic and how Arctic infrastructure and exploration and production of natural resources are affected. Freshwater availability may increase in the Arctic in the future in response to an increase in middle- and high-latitude annual precipitation. Changes in type of precipitation, its seasonal distribution, timing, and rate of snowmelt represent a challenge to municipalities and transportation networks subjected to flooding and droughts and to current industries and future industrial development. A reliable well-distributed water source is essential for all infrastructures, industrial development, and other sectorial uses in the Arctic. Fluctuations in water supply and seasonal precipitation and temperature may represent not only opportunities but also threats to water quantity and quality for Arctic communities and industrial use. The impact of future climate change is varying depending on the geographical area and the current state of infrastructure and industrial development. This paper provides a summary of our current knowledge related to the system function and key physical processes affecting northern water resources, industry, and other sectorial infrastructure.

  7. Biodiversity of the Arctic Ocean in the Face of Climate Change

    NASA Astrophysics Data System (ADS)

    Węsławski, Jan Marcin

    2011-01-01

    Global climate changes which has been observed over the recent years affects organisms occurring in the Arctic seas and the functioning of the whole maritime ecosystems there. The research note presents and briefly analyses the biological diversity of the Arctic Ocean and the most important factors which change the relations between organisms and the environment in the Arctic.

  8. Biodiversity of the Arctic Ocean in the Face of Climate Change

    NASA Astrophysics Data System (ADS)

    Węsławski, Jan Marcin

    2011-01-01

    Global climate changes which has been observed over the recent years affects organisms occurring in the Arctic seas and the functioning of the whole maritime ecosystems there. The research note presents and briefly analyses the biological diversity of the Arctic Ocean and the most important factors which change the relations between organisms and the environment in the Arctic

  9. a New Japanese Project for Arctic Climate Change Research - Grene Arctic - (Invited)

    NASA Astrophysics Data System (ADS)

    Enomoto, H.

    2013-12-01

    A new Arctic Climate Change Research Project 'Rapid Change of the Arctic Climate System and its Global Influences' has started in 2011 for a five years project. GRENE-Arctic project is an initiative of Arctic study by more than 30 Japanese universities and institutes as the flame work of GRENE (Green Network of Excellence) of MEXT (Ministry of Education, Culture, Sports, Science and Technology, Japan). The GRENE-Arctic project set four strategic research targets: 1. Understanding the mechanism of warming amplification in the Arctic 2. Understanding the Arctic system for global climate and future change 3. Evaluation of the effects of Arctic change on weather in Japan, marine ecosystems and fisheries 4. Prediction of sea Ice distribution and Arctic sea routes This project aims to realize the strategic research targets by executing following studies: -Improvement of coupled general circulation models based on validations of the Arctic climate reproducibility and on mechanism analyses of the Arctic climate change and variability -The role of Arctic cryosphere in the global change -Change in terrestrial ecosystem of pan-Arctic and its effect on climate -Studies on greenhouse gas cycles in the Arctic and their responses to climate change -Atmospheric studies on Arctic change and its global impacts -Ecosystem studies of the Arctic ocean declining Sea ice -Projection of Arctic Sea ice responding to availability of Arctic sea route (* ** ***) *Changes in the Arctic ocean and mechanisms on catastrophic reduction of Arctic sea ice cover **Coordinated observational and modeling studies on the basic structure and variability of the Arctic sea ice-ocean system ***Sea ice prediction and construction of ice navigation support system for the Arctic sea route. Although GRENE Arctic project aims to product scientific contribution in a concentrated program during 2011-2016, Japanese Arctic research community established Japan Consortium for Arctic Environmental Research (JCAR) in May

  10. 78 FR 12033 - Programs and Research Projects Affecting the Arctic

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-21

    ... From the Federal Register Online via the Government Publishing Office ] ARCTIC RESEARCH COMMISSION Programs and Research Projects Affecting the Arctic Notice is hereby given that the U.S. Arctic Research... programs and research projects affecting the Arctic. If you plan to attend this meeting, please notify...

  11. Impact of Holocene climate variability on Arctic vegetation

    NASA Astrophysics Data System (ADS)

    Gajewski, K.

    2015-10-01

    This paper summarizes current knowledge about the postglacial history of the vegetation of the Canadian Arctic Archipelago (CAA) and Greenland. Available pollen data were used to understand the initial migration of taxa across the Arctic, how the plant biodiversity responded to Holocene climate variability, and how past climate variability affected primary production of the vegetation. Current evidence suggests that most of the flora arrived in the area during the Holocene from Europe or refugia south or west of the region immediately after local deglaciation, indicating rapid dispersal of propagules to the region from distant sources. There is some evidence of shrub species arriving later in Greenland, but it is not clear if this is dispersal limited or a response to past climates. Subsequent climate variability had little effect on biodiversity across the CAA, with some evidence of local extinctions in areas of Greenland in the late Holocene. The most significant impact of climate changes is on vegetation density and/or plant production.

  12. Arctic Permafrost and Carbon Climate Feedbacks (Invited)

    NASA Astrophysics Data System (ADS)

    Bruhwiler, L.

    2013-12-01

    Vast stores of organic carbon are thought to be frozen in Arctic soils; as much as 1,700 PgC, several times the amount emitted by fossil fuel use to date and about equal to known coal reserves. If mobilized to the atmosphere, this carbon would have significant impacts on global climate, especially if emitted as CH4, a gas that is about 25 times more potent a greenhouse gas per mass than CO2 over a century timescale. Arctic temperatures have been increasing rapidly over the last several decades, with melting of ice both on sea and land, sometimes at surprisingly fast rates. Human activities in the Arctic are sure to expand as the climate moderates, and one of the challenges confronting our ability to predict the future global climate is understanding the potential evolution of trace gas budgets in the Arctic. Bottom-up estimates from flux towers and chamber studies over the past several decades imply that the Arctic is taking up more CO2 and emitting more CH4. Atmospheric network observations do not currently support long-term increases in CH4 emissions, although inter-annual variability due to year-to-year temperature changes is seen in the atmospheric data. Small changes in CO2 uptake are difficult to detect given the overwhelming dominance of the fossil fuel emissions in the CO2 budget. A commitment to long-term monitoring of greenhouse gases using both regionally representative bottom-up measurements and top-down atmospheric network observations in the Arctic is fundamental to our ability to detect early changes in carbon emissions, as well as to evaluate and test models that predict future carbon cycle climate feedbacks.

  13. Climate sensitivity to Arctic seaway restriction during the early Paleogene

    NASA Astrophysics Data System (ADS)

    Roberts, Christopher D.; LeGrande, Allegra N.; Tripati, Aradhna K.

    2009-09-01

    The opening and closing of ocean gateways affects the global distribution of heat, salt, and moisture, potentially driving climatic change on regional to global scales. Between 65 and 45 million years ago (Ma), during the early Paleogene, exchange between the Arctic and global oceans occurred through two narrow and shallow seaways, the Greenland-Norway seaway and the Turgai Strait. Sediments from the Arctic Ocean suggest that, during this interval, the surface ocean was warm, brackish, and episodically enabled the freshwater fern Azolla to bloom. The precise mechanisms responsible for the development of these conditions in the Paleogene Arctic remain uncertain. Here we show results from an isotope-enabled, atmosphere-ocean general circulation model, which indicate that Northern Hemisphere climate would have been very sensitive to the degree of oceanic exchange through the Arctic seaways. We also present modelled estimates of seawater and calcite δ18O for the Paleogene. By restricting these seaways, we simulate freshening of the surface Arctic Ocean to ~ 6 psu and warming of sea-surface temperatures by 2 °C in the North Atlantic and 5-10 °C in the Labrador Sea. Our results may help explain the occurrence of low-salinity tolerant taxa in the Arctic Ocean during the Eocene and provide a mechanism for enhanced warmth in the north western Atlantic. We propose that the formation of a volcanic land-bridge between Greenland and Europe could have caused increased ocean convection and warming of intermediate waters in the Atlantic. If true, this result is consistent with the theory that bathymetry changes may have caused thermal destabilisation of methane clathrates and supports a tectonic trigger hypothesis for the Paleocene Eocene Thermal Maximum (PETM).

  14. Multiple climate drivers accelerate Arctic plant community senescence

    NASA Astrophysics Data System (ADS)

    Livensperger, C.; Steltzer, H.; Wallenstein, M. D.; Weintraub, M. N.

    2015-12-01

    Alteration of seasonal phenology cues due to climate change has led to changes in the onset and duration of the growing season. While photoperiod often acts as an ultimate control on phenological events, recent studies have shown that environmental cues such as temperature and soil water content can modify the direction and rate of senescence processes. Warmer temperatures have resulted in an observed trend towards delayed senescence across temperate latitudes. However, Arctic regions are characterized by extreme seasonality and rapidly decreasing photoperiod, and consequently senescence may not shift as climate warms. We monitored the timing of Arctic plant community senescence for three years under the framework of an experimental manipulation that altered seasonal phenological cues through warming and earlier snowmelt. Alternative models of senescence were tested to determine if microclimate (air temperature, soil temperature, and soil moisture) or start of season phenology affect the timing and rate of community senescence. We found that all three microclimate predictors contributed to explaining variation in timing of senescence, suggesting that photoperiod is not the sole control on timing of senescence in Arctic plant communities. Rather, increased air and soil temperatures along with drier soil conditions, led to acceleration in the onset of senescence at a community level. Our data suggest that (1) multiple climate drivers predict timing of plant community senescence, and (2) climate change could result in a shorter peak season due to earlier onset of senescence, which would decrease the potential carbon uptake in moist acidic tundra.

  15. A Synthesis of Arctic Weather and Climate

    NASA Astrophysics Data System (ADS)

    Bromwich, D. H.; Hines, K. M.

    2008-12-01

    In the polar regions, its is difficult to place current weather and climate trends in a long-term climatological perspective, primarily because the meteorological records there are limited in time and space in comparison with other regions of the globe. The low spatial density of polar meteorological data makes it challenging to attribute changes to local effects or to hemispheric teleconnections. Reanalyses, which assimilate all available observations into physically-consistent, regularly-spaced and comprehensive datasets, can be especially helpful in these latitudes. The timeliness of such efforts is especially pronounced given the recently-observed dramatic changes in Arctic sea ice, land ice, and permafrost regions, whose causes are being debated. A new physically-consistent synthesis of Arctic observations will be achieved through the high-resolution reanalysis of the northern high latitude region, spanning poleward from the headwaters of the northward flowing rivers. The ASR is a collaboration of the Ohio State University, the National Center Atmospheric Research, the University of Colorado, the University of Illinois, and the University of Alaska-Fairbanks. The production phase of the initial ASR has been funded by the National Science Foundation as an International Polar Year (IPY 2007-2009) project covering 2000-2010. The ASR will provide a high resolution description in space (15 km) and time (1-3 h) of the coupled atmosphere-sea ice-land surface system of the Arctic. Ingested historical data streams from the surface and space, along with measurements of the physical components of the Arctic Observing Network being developed as part of IPY will be assimilated by the ASR. Gridded output fields from the ASR will serve a variety of uses such drivers for coupled ice-ocean, land surface and other models, and will offer a focal point for coordinated model inter-comparison efforts. The ASR will permit detailed reconstructions of the Arctic system's variability

  16. Arctic cities and climate change: climate-induced changes in stability of Russian urban infrastructure built on permafrost

    NASA Astrophysics Data System (ADS)

    Shiklomanov, Nikolay; Streletskiy, Dmitry; Swales, Timothy

    2014-05-01

    Planned socio-economic development during the Soviet period promoted migration into the Arctic and work force consolidation in urbanized settlements to support mineral resources extraction and transportation industries. These policies have resulted in very high level of urbanization in the Soviet Arctic. Despite the mass migration from the northern regions during the 1990s following the collapse of the Soviet Union and the diminishing government support, the Russian Arctic population remains predominantly urban. In five Russian Administrative regions underlined by permafrost and bordering the Arctic Ocean 66 to 82% (depending on region) of the total population is living in Soviet-era urban communities. The political, economic and demographic changes in the Russian Arctic over the last 20 years are further complicated by climate change which is greatly amplified in the Arctic region. One of the most significant impacts of climate change on arctic urban landscapes is the warming and degradation of permafrost which negatively affects the structural integrity of infrastructure. The majority of structures in the Russian Arctic are built according to the passive principle, which promotes equilibrium between the permafrost thermal regime and infrastructure foundations. This presentation is focused on quantitative assessment of potential changes in stability of Russian urban infrastructure built on permafrost in response to ongoing and future climatic changes using permafrost - geotechnical model forced by GCM-projected climate. To address the uncertainties in GCM projections we have utilized results from 6 models participated in most recent IPCC model inter-comparison project. The analysis was conducted for entire extent of Russian permafrost-affected area and on several representative urban communities. Our results demonstrate that significant observed reduction in urban infrastructure stability throughout the Russian Arctic can be attributed to climatic changes and that

  17. The Arctic Ocean and climate: A Perspective

    NASA Astrophysics Data System (ADS)

    Aagaard, K.; Carmack, E. C.

    The most likely effects of the Arctic Ocean on global climate are through the surface heat balance and the thermohaline circulation. The former is intimately related to the stratification of the Arctic Ocean, while the latter may be significantly controlled by outflow from the Arctic Ocean into the major convective regions to the south. Evaluating these issues adequately requires detailed knowledge of the density structure and circulation of the Arctic Ocean and of their variability. New long time series of temperature and salinity (T/S) from the Canadian Basin show a grainy T/S structure, probably on a horizontal scale of a few tens of kilometers. The temperature field is particularly inhomogeneous, since for cold water it is not greatly constrained by buoyancy forces. The simultaneous velocity time series show that the grainy T/S structure results from a complex eddy field, often with vertically or horizontally paired counter-rotating eddies drifting with a slow larger-scale flow. The ocean is therefore not well mixed on these scales. Finally, we note that the ventilation of the interior Arctic Ocean from the adjacent shelves appears to be highly variable on an interannual basis, and indeed may not be robust on longer time scales. In particular we note the absence, or near-absence, of deep ventilation of the Canadian Basin during the last 500 years. Based on the 14C model of Macdonald et al. [1993], however, we hypothesize that these same waters were ventilated prior to that time and that the deep convective shutdown about 500 years ago coincided with the end of the whale-hunting Thule culture. We further suggest that the two events had a common cause, viz., the increase of sea ice over the continental shelves during summer.

  18. Arctic Sea Ice Changes, Interactions, and Feedbacks on the Arctic Climate during the Satellite Era

    NASA Astrophysics Data System (ADS)

    Wang, X.; Key, J. R.; Liu, Y.

    2011-12-01

    Of all the components of the Earth climate system, the cryosphere is arguably the least understood even though it is a very important indicator and an effective modulator of regional and global climate change. Changes in sea ice will significantly affect exchanges of momentum, heat, and mass between the ocean and the atmosphere, and have profound socio-economic impacts on transportation, fisheries, hunting, polar animal habitat and more. In the last three decades, the Arctic underwent significant changes in sea ice as part of the accelerated global climate change. With the recently developed One-dimensional Thermodynamic Ice Model (OTIM), sea and lake ice thickness and trends can be reasonably estimated. The OTIM has been extensively validated against submarine and moored upward-looking sonar measurements, meteorological station measurements, and comprehensive numerical model simulations. The Extended AVHRR Polar Pathfinder (APP-x) dataset has 25 climate parameters covering surface, cloud, and sea ice properties as well as surface and top-of-atmosphere radiative fluxes for the period 1982 - 2004 over the Arctic and Antarctic at 25 km resolution. The OTIM has been used with APP-x dataset for Arctic sea ice thickness and volume estimation. Statistical analysis of spatial and temporal distributions and trends in sea ice extent, thickness, and volume over the satellite period has been performed, along with the temporal analysis of first year and multiple year sea ice extent changes. Preliminary results show clear evidence that Arctic sea ice has been experiencing significant changes over the last two decades of the 20th century. The Arctic sea ice has been shrinking unexpectedly fast with the declines in sea ice extent, thickness, and volume, most apparent in the fall season. Moreover, satellites provide an unprecedented opportunity to observe Arctic sea ice and its changes with high spatial and temporal coverage that is making it an ideal data source for mitigating

  19. Responses of arctic and alpine ecosystems to altered seasonality under climate change

    NASA Astrophysics Data System (ADS)

    Ernakovich, J. G.; Hopping, K. A.; Berdanier, A.; Simpson, R. T.; Kachergis, E. J.; Steltzer, H.; Wallenstein, M. D.

    2012-12-01

    Arctic and alpine ecosystems are largely structured by strong seasonal patterns in abiotic drivers, including solar radiation and air and soil temperature. Because air temperature and precipitation patterns are changing rapidly, the length of the growing season is increasing due to shifts in snowfall, earlier snowmelt in spring, and delayed snowfall in autumn. Although arctic and alpine environments are both characterized by short growing seasons, they differ in fundamental ways that will affect their responses to changing seasonality. We compare meteorological data from sixteen arctic and alpine sites and biological data from two arctic and two alpine sites. We propose that although alpine and arctic ecosystems appear similar under historical climate conditions, especially during the growing season, winter conditions and climate change will result in divergent responses. Biotic responses to changing seasonality will affect belowground and aboveground community composition, trophic dynamics, and the functioning of these ecosystems, including net carbon balance.

  20. Program for Arctic Regional Climate Assessment (PARCA)

    NASA Technical Reports Server (NTRS)

    Gogineni, Sivaprasad; Thomas, Robert H.; Abdalati, Waleed (Editor)

    1999-01-01

    The Program for Arctic Regional Climate Assessment (PARCA) is a NASA-sponsored initiative with the prime objective of understanding the mass balance of the Greenland ice sheet. In October 1998, PARCA investigators met to review activities of the previous year, assess the program's progress, and plan future investigations directed at accomplishing that objective. Some exciting results were presented and discussed, including evidence of dramatic thinning of the ice sheet near the southeastern coast. Details of the investigations and many of the accomplishments are given in this report, but major highlights are given in the Executive Summary of the report.

  1. Climate Change: Science and Policy in the Arctic Climate Change: Science and Policy in the Arctic

    NASA Astrophysics Data System (ADS)

    Bigras, S. C.

    2009-12-01

    It is an accepted fact that the Earth’s climate is warming. Recent research has demonstrated the direct links between the Arctic regions and the rest of the planet. We have become more aware that these regions are feeling the effects of global climate change more intensely than anywhere else on Earth -- and that they are fast becoming the new frontiers for resources and political disputes. This paper examines some of the potential climate change impacts in the Arctic and how the science of climate change can be used to develop policies that will help mitigate some of these impacts. Despite the growing body of research we do not yet completely understand the potential consequences of climate change in the Arctic. Climate models predict significant changes and impacts on the northern physical environment and renewable resources, and on the communities and societies that depend on them. Policies developed and implemented as a result of the research findings will be designed to help mitigate some of the more serious consequences. Given the importance of cost in making policy decisions, the financial implications of different scenarios will need to be considered. The Arctic Ocean Basin is a complex and diverse environment shared by five Arctic states. Cooperation among the states surrounding the Arctic Ocean is often difficult, as each country has its own political and social agenda. Northerners and indigenous peoples should be engaged and able to influence the direction of northern adaptation policies. Along with climate change, the Arctic environment and Arctic residents face many other challenges, among them safe resource development. Resource development in the Arctic has always been a controversial issue, seen by some as a solution to high unemployment and by others as an unacceptably disruptive and destructive force. Its inherent risks need to be considered: there are needs for adaptation, for management frameworks, for addressing cumulative effects, and for

  2. Climate Change, Globalization and Geopolitics in the New Maritime Arctic

    NASA Astrophysics Data System (ADS)

    Brigham, L. W.

    2011-12-01

    Early in the 21st century a confluence of climate change, globalization and geopolitics is shaping the future of the maritime Arctic. This nexus is also fostering greater linkage of the Arctic to the rest of the planet. Arctic sea ice is undergoing a historic transformation of thinning, extent reduction in all seasons, and reduction in the area of multiyear ice in the central Arctic Ocean. Global Climate Model simulations of Arctic sea ice indicate multiyear ice could disappear by 2030 for a short period of time each summer. These physical changes invite greater marine access, longer seasons of navigation, and potential, summer trans-Arctic voyages. As a result, enhanced marine safety, environmental protection, and maritime security measures are under development. Coupled with climate change as a key driver of regional change is the current and future integration of the Arctic's natural wealth with global markets (oil, gas and hard minerals). Abundant freshwater in the Arctic could also be a future commodity of value. Recent events such as drilling for hydrocarbons off Greenland's west coast and the summer marine transport of natural resources from the Russian Arctic to China across the top of Eurasia are indicators of greater global economic ties to the Arctic. Plausible Arctic futures indicate continued integration with global issues and increased complexity of a range of regional economic, security and environmental challenges.

  3. Impacts of volcanic eruptions and geoengineering on Arctic climate

    NASA Astrophysics Data System (ADS)

    Berdahl, Mira

    Stratospheric aerosols can produce large radiative forcing and climate response, often amplified in the Arctic. Here I study the Arctic response to natural (volcanic eruptions) and potential anthropogenic (geoengineering) stratospheric sulfate aerosols. I use a regional climate model and global climate model output from two modeling intercomparison projects. First, I investigate the relative impacts of changes in radiation and advection on snow extent over Baffin Island with the Weather Research and Forecasting model. Model results show it is possible to suddenly lower the snowline by amounts comparable to those seen during the Little Ice Age with an average temperature decrease of --3.9 +/- 1.1 K from present. Further, sea ice expansion following large volcanic eruptions would have significant affects on inland temperatures, especially in the fall. Next, I analyze Last Millennium simulations from the Paleoclimate Modeling Intercomparison Project 3 to assess whether state-of-the-art global climate models produce sudden changes and persistence of cold conditions after large volcanic eruptions as inferred by geological records and previous climate modeling. North Atlantic sea ice and Baffin Island snow cover showed large-scale expansion in the simulations, but none of the models produced significant centennial-scale effects. Warm Baffin Island summer climates stunt snow expansion in some models completely, and model topography misses the critical elevations that could sustain snow on the island. This has critical consequences for ice and snow formation and persistence in regions such as the Arctic where temperatures are near freezing and small temperature changes affect the state of water. Finally, I analyze output from the Geoengineering Modeling Intercomparison Project to examine whether geoengineering by injection of sulfate aerosols into the lower stratosphere prevents the demise of minimum annual sea ice extent, or slows spring snow cover loss. Despite

  4. Arctic sea ice and Eurasian climate: A review

    NASA Astrophysics Data System (ADS)

    Gao, Yongqi; Sun, Jianqi; Li, Fei; He, Shengping; Sandven, Stein; Yan, Qing; Zhang, Zhongshi; Lohmann, Katja; Keenlyside, Noel; Furevik, Tore; Suo, Lingling

    2015-01-01

    The Arctic plays a fundamental role in the climate system and has shown significant climate change in recent decades, including the Arctic warming and decline of Arctic sea-ice extent and thickness. In contrast to the Arctic warming and reduction of Arctic sea ice, Europe, East Asia and North America have experienced anomalously cold conditions, with record snowfall during recent years. In this paper, we review current understanding of the sea-ice impacts on the Eurasian climate. Paleo, observational and modelling studies are covered to summarize several major themes, including: the variability of Arctic sea ice and its controls; the likely causes and apparent impacts of the Arctic sea-ice decline during the satellite era, as well as past and projected future impacts and trends; the links and feedback mechanisms between the Arctic sea ice and the Arctic Oscillation/North Atlantic Oscillation, the recent Eurasian cooling, winter atmospheric circulation, summer precipitation in East Asia, spring snowfall over Eurasia, East Asian winter monsoon, and midlatitude extreme weather; and the remote climate response (e.g., atmospheric circulation, air temperature) to changes in Arctic sea ice. We conclude with a brief summary and suggestions for future research.

  5. Gender Specific Reproductive Strategies of an Arctic Key Species (Boreogadus saida) and Implications of Climate Change

    PubMed Central

    Nahrgang, Jasmine; Varpe, Øystein; Korshunova, Ekaterina; Murzina, Svetlana; Hallanger, Ingeborg G.; Vieweg, Ireen; Berge, Jørgen

    2014-01-01

    The Arctic climate is changing at an unprecedented rate. What consequences this may have on the Arctic marine ecosystem depends to a large degree on how its species will respond both directly to elevated temperatures and more indirectly through ecological interactions. But despite an alarming recent warming of the Arctic with accompanying sea ice loss, reports evaluating ecological impacts of climate change in the Arctic remain sparse. Here, based upon a large-scale field study, we present basic new knowledge regarding the life history traits for one of the most important species in the entire Arctic, the polar cod (Boreogadus saida). Furthermore, by comparing regions of contrasting climatic influence (domains), we present evidence as to how its growth and reproductive success is impaired in the warmer of the two domains. As the future Arctic is predicted to resemble today's Atlantic domains, we forecast changes in growth and life history characteristics of polar cod that will lead to alteration of its role as an Arctic keystone species. This will in turn affect community dynamics and energy transfer in the entire Arctic food chain. PMID:24871481

  6. Arctic ocean sediment texture and the Pleistocene climate cycle

    SciTech Connect

    Clark, D.L.; Morris, T.H.

    1985-01-01

    Arctic Ocean sediment texture accurately reflects the Plio-Pleistocene climate cycle. The precision of paleoclimate interpretation is improved when deglaciation is recognized as a distinct climate stage, overlapping both glacial and interglacial stages, and for the later Pleistocene, perhaps never completed. Oxygen isotope stratigraphy and foraminifera productivity are out of phase but can be understood in the context of the transitional nature of the glacial, deglacial and interglacial climate stages of the Arctic Ocean.

  7. Can regional climate engineering save the summer Arctic sea ice?

    NASA Astrophysics Data System (ADS)

    Tilmes, S.; Jahn, Alexandra; Kay, Jennifer E.; Holland, Marika; Lamarque, Jean-Francois

    2014-02-01

    Rapid declines in summer Arctic sea ice extent are projected under high-forcing future climate scenarios. Regional Arctic climate engineering has been suggested as an emergency strategy to save the sea ice. Model simulations of idealized regional dimming experiments compared to a business-as-usual greenhouse gas emission simulation demonstrate the importance of both local and remote feedback mechanisms to the surface energy budget in high latitudes. With increasing artificial reduction in incoming shortwave radiation, the positive surface albedo feedback from Arctic sea ice loss is reduced. However, changes in Arctic clouds and the strongly increasing northward heat transport both counteract the direct dimming effects. A 4 times stronger local reduction in solar radiation compared to a global experiment is required to preserve summer Arctic sea ice area. Even with regional Arctic dimming, a reduction in the strength of the oceanic meridional overturning circulation and a shut down of Labrador Sea deep convection are possible.

  8. Climate change and zoonotic infections in the Russian Arctic

    PubMed Central

    Revich, Boris; Tokarevich, Nikolai; Parkinson, Alan J.

    2012-01-01

    Climate change in the Russian Arctic is more pronounced than in any other part of the country. Between 1955 and 2000, the annual average air temperature in the Russian North increased by 1.2°C. During the same period, the mean temperature of upper layer of permafrost increased by 3°C. Climate change in Russian Arctic increases the risks of the emergence of zoonotic infectious diseases. This review presents data on morbidity rates among people, domestic animals and wildlife in the Russian Arctic, focusing on the potential climate related emergence of such diseases as tick-borne encephalitis, tularemia, brucellosis, leptospirosis, rabies, and anthrax. PMID:22868189

  9. Climate Effects on Methylmercury Bioaccumulation Along a Latitudinal Gradient in the Eastern Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Chetelat, J.; Richardson, M.; MacMillan, G. A.; Amyot, M.; Hintelmann, H.; Crump, D.

    2014-12-01

    Recent evidence indicates that inorganic mercury (Hg) loadings to Arctic lakes decline with latitude. However, monomethylmercury (MMHg) concentrations in fish and their prey do not decline in a similar fashion, suggesting that higher latitude lakes are more vulnerable to Hg inputs. Preliminary results will be presented from a three-year study (2012-2015) of climate effects on MMHg bioaccumulation in lakes of the eastern Canadian Arctic. We have investigated mercury transport and accumulation processes in lakes and ponds from three study regions along a latitudinal gradient in climate-controlled ecosystem types in the Canadian Arctic, specifically sub-Arctic taiga, Arctic tundra and polar desert. In each water body, we measured key aspects of MMHg bioaccumulation—MMHg bioavailability to benthic food webs and organism growth rates—as well as how watershed characteristics affect the transport of Hg and organic carbon to lakes. Novel approaches were incorporated including the use of passive samplers (Diffusive Gradient in Thin Film samplers or DGTs) to estimate sediment bioavailable MMHg concentrations and tissue RNA content to compare organism short-term growth rates. A comparison of Arctic tundra and sub-Arctic taiga lakes showed that surface water concentrations of MMHg were strongly and positively correlated to total Hg concentrations both within and among study regions, implying strong control of inorganic Hg supply. Sediment concentrations of bioavailable MMHg were highly variable among lakes, although average concentrations were similar between study regions. Local environmental conditions appear to have a strong influence on sediment potential for MMHg supply. Lake-dwelling Arctic char from tundra lakes had similar or higher total Hg concentrations compared with brook trout from sub-Arctic lakes that were exposed to higher water MMHg concentrations. Potential environmental drivers of these patterns will be discussed. This latitudinal study will provide new

  10. The Arctic Climate Modeling Program: Professional Development for Rural Teachers

    ERIC Educational Resources Information Center

    Bertram, Kathryn Berry

    2010-01-01

    The Arctic Climate Modeling Program (ACMP) offered yearlong science, technology, engineering, and math (STEM) professional development to teachers in rural Alaska. Teacher training focused on introducing youth to workforce technologies used in Arctic research. Due to challenges in making professional development accessible to rural teachers, ACMP…

  11. Integrated regional changes in arctic climate feedbacks: Implications for the global climate system

    USGS Publications Warehouse

    McGuire, A.D.; Chapin, F. S., III; Walsh, J.E.; Wirth, C.

    2006-01-01

    The Arctic is a key part of the global climate system because the net positive energy input to the tropics must ultimately be resolved through substantial energy losses in high-latitude regions. The Arctic influences the global climate system through both positive and negative feedbacks that involve physical, ecological, and human systems of the Arctic. The balance of evidence suggests that positive feedbacks to global warming will likely dominate in the Arctic during the next 50 to 100 years. However, the negative feedbacks associated with changing the freshwater balance of the Arctic Ocean might abruptly launch the planet into another glacial period on longer timescales. In light of uncertainties and the vulnerabilities of the climate system to responses in the Arctic, it is important that we improve our understanding of how integrated regional changes in the Arctic will likely influence the evolution of the global climate system. Copyright ?? 2006 by Annual Reviews. All rights reserved.

  12. Long-term trends of the Polar and Arctic cells influencing the Arctic climate since 1989

    NASA Astrophysics Data System (ADS)

    Qian, Weihong; Wu, Kaijun; Leung, Jeremy Cheuk-Hin; Shi, Jian

    2016-03-01

    The strengthening and broadening trends of the Hadley cell have been revealed, while the existence of the Arctic cell has also been confirmed in previous studies. This study extends previous strengthening trend analyses of the Hadley cell to the Polar and Arctic cells in the Northern Hemisphere and explores their climate influences. Results show that the Polar cell experienced an abrupt change from a slow to a rapid strengthening trend in 1989, while the Arctic cell showed an insignificant strengthening trend and a significant weakening trend successively. The strengthening subsidence flow associated with the Polar and Arctic cells can partly explain the warming surface air temperature and declining sea ice concentration through the increasing tropospheric height and temperature trends. These results provide new insights for understanding the interdecadal relationship between atmospheric circulation and climate change in the Arctic region.

  13. Climate science: A great Arctic ice shelf

    NASA Astrophysics Data System (ADS)

    Domack, Eugene

    2016-02-01

    Newly mapped features on the floor of the Arctic Ocean suggest that the Arctic basin was once covered by a one-kilometre-thick, flowing ice shelf derived from large ice sheets in eastern Siberia, Arctic Canada and the Barents Sea.

  14. Arctic Vegetation Change and Feedbacks under Future Climate (Invited)

    NASA Astrophysics Data System (ADS)

    Goetz, S. J.; Loranty, M. M.; Beck, P.; Phillips, S.; Damoulas, T.; Pearson, R. G.

    2013-12-01

    .27 Pg) were roughly equivalent to the projected annual efflux of soil carbon to the atmosphere as a consequence of permafrost thaw over the coming century. In contrast, changes in Spring-Summer albedo (α) and net surface shortwave radiation (SN) indicate the significant extent to which vegetation change will influence climate. We estimate that α will decrease by 2-6% under restricted tree dispersal and by 10-26% under equilibrium, corresponding to increases in SN of 1.07-3.11 W m-2 and 3.54-8.71 W m-2 under the same two scenarios. These changes are largely due to the snow masking effects of taller vegetation, indicating the projected vegetation changes would exacerbate currently amplified rates of regional warming. Our predictions thereby indicate that vegetation in the Arctic will affect climate primarily as a biophysical medium, whereas the carbon implications of Arctic change are largely those that influence permafrost and associated soil carbon stocks. As with thawing permafrost, vegetation distribution shifts will result in an overall positive feedback to climate that is likely to cause greater warming than has previously been predicted.

  15. North Pacific climate variability and Arctic sea ice

    NASA Astrophysics Data System (ADS)

    Linkin, Megan E.

    Boreal winter North Pacific climate variability strongly influences North American hydroclimate and Arctic sea ice distribution in the marginal Arctic seas. Two modes of atmospheric variability explaining 53% of the variance in the Pacific Ocean sea level pressure (SLP) field are extracted and identified: the Pacific-North American (PNA) teleconnection and the North Pacific Oscillation/West Pacific (NPO/WP) teleconnection. The NPO/WP, a dipole in North Pacific SLP and geopotential heights, is affiliated with latitudinal displacements of the Asian Pacific jet and an intensification of the Pacific stormtrack. The North American hydroclimate impacts of the NPO/WP are substantial; its impact on Alaska, Pacific Northwest and Great Plains precipitation is more influential than both the PNA and the El Nino-Southern Oscillation (ENSO). The NPO/WP is also strongly associated with a contemporaneous extension of the marginal ice zone (MIZ) in the western Bering Sea and Sea of Okhotsk and MIZ retreat in the eastern Bering Sea. Wintertime climate variability also significantly impacts the distribution of Arctic sea ice during the subsequent summer months, due to the hysteretic nature of the ice cap. The North Atlantic Oscillation (NAO) is known for its effects on summer sea ice distribution; this study extends into the Pacific and finds that circulation anomalies related to Pacific sea surface temperature (SST) variability also strongly impact summer Arctic sea ice. The NAO and ENSO are related to sea ice decline in the Eastern Siberian Sea, where the linear trend since 1979 is 25% per decade. PDV affects sea ice in the eastern Arctic, a region which displays no linear trend since 1979. The low frequency of PDV variability and the persistent positive NAO during the 1980s and 1990s results in natural variability being aliased into the total linear trend in summer sea ice calculated from satellite-based sea ice concentration. Since 1979, natural variability accounts for 30% of

  16. Evidence and implications of recent climate change in Northern Alaska and other Arctic regions

    USGS Publications Warehouse

    Hinzman, L.D.; Bettez, N.D.; Bolton, W.R.; Chapin, F.S.; Dyurgerov, M.B.; Fastie, C.L.; Griffith, B.; Hollister, R.D.; Hope, A.; Huntington, H.P.; Jensen, A.M.; Jia, G.J.; Jorgenson, T.; Kane, D.L.; Klein, D.R.; Kofinas, G.; Lynch, A.H.; Lloyd, A.H.; McGuire, A.D.; Nelson, F.E.; Oechel, W.C.; Osterkamp, T.E.; Racine, C.H.; Romanovsky, V.E.; Stone, R.S.; Stow, D.A.; Sturm, M.; Tweedie, C.E.; Vourlitis, G.L.; Walker, M.D.; Walker, D. A.; Webber, P. J.; Welker, J.M.; Winker, K.S.; Yoshikawa, K.

    2005-01-01

    The Arctic climate is changing. Permafrost is warming, hydrological processes are changing and biological and social systems are also evolving in response to these changing conditions. Knowing how the structure and function of arctic terrestrial ecosystems are responding to recent and persistent climate change is paramount to understanding the future state of the Earth system and how humans will need to adapt. Our holistic review presents a broad array of evidence that illustrates convincingly; the Arctic is undergoing a system-wide response to an altered climatic state. New extreme and seasonal surface climatic conditions are being experienced, a range of biophysical states and processes influenced by the threshold and phase change of freezing point are being altered, hydrological and biogeochemical cycles are shifting, and more regularly human sub-systems are being affected. Importantly, the patterns, magnitude and mechanisms of change have sometimes been unpredictable or difficult to isolate due to compounding factors. In almost every discipline represented, we show how the biocomplexity of the Arctic system has highlighted and challenged a paucity of integrated scientific knowledge, the lack of sustained observational and experimental time series, and the technical and logistic constraints of researching the Arctic environment. This study supports ongoing efforts to strengthen the interdisciplinarity of arctic system science and improve the coupling of large scale experimental manipulation with sustained time series observations by incorporating and integrating novel technologies, remote sensing and modeling. ?? Springer 2005.

  17. Evidence and Implications of Recent Climate Change in Northern Alaska and Other Arctic Regions

    NASA Astrophysics Data System (ADS)

    Hinzman, L. D.; Bettez, N.; Bolton, W. R.; Chapin, F. S.; Dyurgerov, M. B.; Fastie, C. L.; Griffith, B.; Hollister, R. D.; Hope, A.; Huntington, H. P.; Jensen, A. M.; Jia, G. J.; Jorgenson, T.; Kane, D. L.; Klein, D. R.; Kofinas, G.; Lynch, A. H.; Lloyd, A. H.; McGuire, A. D.; Nelson, F. E.; Nolan, M.; Oechel, W. C.; Osterkamp, T. E.; Racine, C. H.; Romanovsky, V. E.; Stone, R. S.; Stow, D. A.; Sturm, M.; Tweedie, C. E.; Vourlitis, G. L.; Walker, M. D.; Walker, D. A.; Webber, P. J.; Welker, J.; Winker, K. S.; Yoshikawa, K.

    2004-12-01

    The Arctic climate is changing. Permafrost is warming, hydrological processes are changing and biological and social systems are also evolving in response to these changing conditions. Knowing how the structure and function of arctic terrestrial ecosystems are responding to recent and persistent climate change is paramount to understanding the future state of the Earth system and how humans will need to adapt. Our holistic review presents a broad array of evidence that illustrates convincingly; the Arctic is undergoing a system-wide response to an altered climatic state. New extreme and seasonal surface climatic conditions are being experienced, a range of biophysical states and processes influenced by the threshold and phase change of freezing point are being altered, hydrological and biogeochemical cycles are shifting, and more regularly human sub-systems are being affected. Importantly, the patterns, magnitude and mechanisms of change have sometimes been unpredictable or difficult to isolate due to compounding factors. In almost every discipline represented, we show how the biocomplexity of the Arctic system has highlighted and challenged a paucity of integrated scientific knowledge, the lack of sustained observational and experimental time series, and the technical and logistic constraints of researching the Arctic environment. This study supports ongoing efforts to strengthen the interdisciplinarity of arctic system science and improve the coupling of large scale experimental manipulation with sustained time series observations by incorporating and integrating novel technologies, remote sensing and modeling.

  18. Influence of altered low cloud parameterizations for seasonal variation of Arctic cloud amount on climate feedbacks

    NASA Astrophysics Data System (ADS)

    Kim, Yoojin; Choi, Yong-Sang; Kim, Baek-Min; Kim, Hyerim

    2015-12-01

    This study investigates the alteration of climate feedbacks due to overestimated wintertime low-level cloud amount bias over the Arctic region (60°N-90°N) in a climate model. The climate feedback was quantitatively examined through radiative kernels that are pre-calculated radiative responses of climate variables to doubling of carbon dioxide concentration in NCAR Community Atmosphere Model version 3 (CAM3). Climate models have various annual cycle of the Arctic cloud amount at the low-level particularly with large uncertainty in winter and CAM3 may tend to overestimate the Arctic low-level cloud. In this study, the seasonal variation of low-level cloud amount was modified by reducing the wintertime cloud amount by up to 35 %, and then compared with the original without seasonal variation. Thus, we investigate how that bias may affect climate feedbacks and the projections of future Arctic warming. The results show that the decrease in low-level cloud amount slightly affected the radiation budgets because of a small amount of incident solar insolation in winter, but considerably changed water vapor and temperature profiles. Consequently, the most distinctive was decreases in water vapor feedback and contribution of heat transport (by -0.20 and -0.55 W m-2 K-1, respectively) and increases in the lapse rate feedback and cloud feedback (by 0.13 and 0.58 W m-2 K-1, respectively) during winter in this model experiment. This study suggests that the change in Arctic cloud amount effectively reforms the contributions of individual climate feedbacks to Arctic climate system and leads to opposing effects on different feedbacks, which cancel out in the model.

  19. Eocene Arctic Ocean and earth's Early Cenozoic climate

    SciTech Connect

    Clark, D.L.

    1985-01-01

    Seasonal changes of the Arctic Ocean are an approximate microcosm of the present advanced interglacial climate of the Earth. A similar relationship has existed for several million years but was the Early Cenozoic Arctic Ocean an analog of Earth's climate, as well. Absence of polar ice during the Cretaceous is relatively well established. During the Cenozoic a worldwide decrease in mean annual ocean temperature resulted from such factors as altered oceanic circulation and lower atmospheric CO/sub 2/ levels. Limited Arctic Ocean data for the middle or late Eocene indicate the presence of upwelling conditions and accompanying high productivity of diatoms, ebridians, silicoflagellates and archaeomonads. During this interval, some seasonality is suggested from the varve-like nature of a single sediment core. However, the absence of drop stones or any ice-rafted sediment supports the idea of an open water, ice-free central Arctic Ocean during this time. Latest Cretaceous Arctic Ocean sediment is interpreted to represent approximately the same conditions as those suggested for the Eocene and together with that data suggest that the central Arctic Ocean was ice-free during part if not all of the first 20 my of the Cenozoic. Sediment representing the succeeding 30 my has not been recovered but by latest Miocene or earl Pliocene, ice-rafted sediment was accumulating, both pack ice and icebergs covered the Arctic Ocean reflecting cyclic glacial climate.

  20. Arctic Climate Change: A Tale of Two Cod Species

    EPA Science Inventory

    Arctic cod play an important role in the Arctic trophic hierarchy as the consumer of primary productivity and a food source for many marine fish and mammals. Shifts in their distribution and abundance could have cascading affects in the marine environment. This paper investigates...

  1. Arctic climate response to geoengineering with stratospheric sulfate aerosols

    NASA Astrophysics Data System (ADS)

    McCusker, K. E.; Battisti, D. S.; Bitz, C. M.

    2010-12-01

    Recent warming and record summer sea-ice area minimums have spurred expressions of concern for arctic ecosystems, permafrost, and polar bear populations, among other things. Geoengineering by stratospheric sulfate aerosol injections to deliberately cancel the anthropogenic temperature rise has been put forth as a possible solution to restoring Arctic (and global) climate to modern conditions. However, climate is particularly sensitive in the northern high latitudes, responding easily to radiative forcing changes. To that end, we explore the extent to which tropical injections of stratospheric sulfate aerosol can accomplish regional cancellation in the Arctic. We use the Community Climate System Model version 3 global climate model to execute simulations with combinations of doubled CO2 and imposed stratospheric sulfate burdens to investigate the effects on high latitude climate. We further explore the sensitivity of the polar climate to ocean dynamics by running a suite of simulations with and without ocean dynamics, transiently and to equilibrium respectively. We find that, although annual, global mean temperature cancellation is accomplished, there is over-cooling on land in Arctic summer, but residual warming in Arctic winter, which is largely due to atmospheric circulation changes. Furthermore, the spatial extent of these features and their concurrent impacts on sea-ice properties are modified by the inclusion of ocean dynamical feedbacks.

  2. Impacts of ocean albedo alteration on Arctic sea ice restoration and Northern Hemisphere climate

    NASA Astrophysics Data System (ADS)

    Cvijanovic, Ivana; Caldeira, Ken; MacMartin, Douglas G.

    2015-04-01

    The Arctic Ocean is expected to transition into a seasonally ice-free state by mid-century, enhancing Arctic warming and leading to substantial ecological and socio-economic challenges across the Arctic region. It has been proposed that artificially increasing high latitude ocean albedo could restore sea ice, but the climate impacts of such a strategy have not been previously explored. Motivated by this, we investigate the impacts of idealized high latitude ocean albedo changes on Arctic sea ice restoration and climate. In our simulated 4xCO2 climate, imposing surface albedo alterations over the Arctic Ocean leads to partial sea ice recovery and a modest reduction in Arctic warming. With the most extreme ocean albedo changes, imposed over the area 70°-90°N, September sea ice cover stabilizes at ˜40% of its preindustrial value (compared to ˜3% without imposed albedo modifications). This is accompanied by an annual mean Arctic surface temperature decrease of ˜2 °C but no substantial global mean temperature decrease. Imposed albedo changes and sea ice recovery alter climate outside the Arctic region too, affecting precipitation distribution over parts of the continental United States and Northeastern Pacific. For example, following sea ice recovery, wetter and milder winter conditions are present in the Southwest United States while the East Coast experiences cooling. We conclude that although ocean albedo alteration could lead to some sea ice recovery, it does not appear to be an effective way of offsetting the overall effects of CO2 induced global warming.

  3. Impacts of ocean albedo alteration on Arctic sea ice restoration and Northern Hemisphere climate

    SciTech Connect

    Cvijanovic, Ivana; Caldeira, Ken; MacMartin, Douglas G.

    2015-04-01

    The Arctic Ocean is expected to transition into a seasonally ice-free state by mid-century, enhancing Arctic warming and leading to substantial ecological and socio-economic challenges across the Arctic region. It has been proposed that artificially increasing high latitude ocean albedo could restore sea ice, but the climate impacts of such a strategy have not been previously explored. Motivated by this, we investigate the impacts of idealized high latitude ocean albedo changes on Arctic sea ice restoration and climate. In our simulated 4xCO₂ climate, imposing surface albedo alterations over the Arctic Ocean leads to partial sea ice recovery and a modest reduction in Arctic warming. With the most extreme ocean albedo changes, imposed over the area 70°–90°N, September sea ice cover stabilizes at ~40% of its preindustrial value (compared to ~3% without imposed albedo modifications). This is accompanied by an annual mean Arctic surface temperature decrease of ~2 °C but no substantial global mean temperature decrease. Imposed albedo changes and sea ice recovery alter climate outside the Arctic region too, affecting precipitation distribution over parts of the continental United States and Northeastern Pacific. For example, following sea ice recovery, wetter and milder winter conditions are present in the Southwest United States while the East Coast experiences cooling. We conclude that although ocean albedo alteration could lead to some sea ice recovery, it does not appear to be an effective way of offsetting the overall effects of CO₂ induced global warming.

  4. Impacts of ocean albedo alteration on Arctic sea ice restoration and Northern Hemisphere climate

    NASA Astrophysics Data System (ADS)

    Cvijanovic, I.; MacMartin, D. G.; Caldeira, K.

    2015-12-01

    The Arctic Ocean is expected to transition into a seasonally ice-free state by mid-century, enhancing Arctic warming and leading to substantial ecological and socio-economic challenges across the Arctic region. It has been proposed that artificially increasing high latitude ocean albedo could restore sea ice, but the climate impacts of such a strategy have not been previously explored. Motivated by this, we investigate the impacts of idealized high latitude ocean albedo changes on Arctic sea ice restoration and climate. In our simulated 4xCO2 climate, imposing surface albedo alterations over the Arctic Ocean leads to partial sea ice recovery and a modest reduction in Arctic warming. With the most extreme ocean albedo changes, imposed over the area 70°-90°N, September sea ice cover stabilizes at ~40% of its preindustrial value (compared to ~3% without imposed albedo modifications).This is accompanied by an annual mean Arctic surface temperature decrease of ~2 °C but no substantial global mean temperature decrease. Imposed albedo changes and sea ice recovery alter climate outside the Arctic region too, affecting precipitation distribution over parts of the continental United States and Northeastern Pacific. For example, following sea ice recovery, wetter and milder winter conditions are present in the Southwest United States while the East Coast experiences cooling. While our model results imply that ocean albedo alteration does not appear to be an effective way of offsetting the overall effects of CO2 induced global warming or achieving full sea ice recovery, we do not exclude that it may represent a possible approach for small-scale (e.g. individual bay or estuary) sea ice restoration.

  5. Impacts of ocean albedo alteration on Arctic sea ice restoration and Northern Hemisphere climate

    DOE PAGESBeta

    Cvijanovic, Ivana; Caldeira, Ken; MacMartin, Douglas G.

    2015-04-01

    The Arctic Ocean is expected to transition into a seasonally ice-free state by mid-century, enhancing Arctic warming and leading to substantial ecological and socio-economic challenges across the Arctic region. It has been proposed that artificially increasing high latitude ocean albedo could restore sea ice, but the climate impacts of such a strategy have not been previously explored. Motivated by this, we investigate the impacts of idealized high latitude ocean albedo changes on Arctic sea ice restoration and climate. In our simulated 4xCO₂ climate, imposing surface albedo alterations over the Arctic Ocean leads to partial sea ice recovery and a modestmore » reduction in Arctic warming. With the most extreme ocean albedo changes, imposed over the area 70°–90°N, September sea ice cover stabilizes at ~40% of its preindustrial value (compared to ~3% without imposed albedo modifications). This is accompanied by an annual mean Arctic surface temperature decrease of ~2 °C but no substantial global mean temperature decrease. Imposed albedo changes and sea ice recovery alter climate outside the Arctic region too, affecting precipitation distribution over parts of the continental United States and Northeastern Pacific. For example, following sea ice recovery, wetter and milder winter conditions are present in the Southwest United States while the East Coast experiences cooling. We conclude that although ocean albedo alteration could lead to some sea ice recovery, it does not appear to be an effective way of offsetting the overall effects of CO₂ induced global warming.« less

  6. Carbon, Climate and Cameras: Showcasing Arctic research through multimedia storytelling

    NASA Astrophysics Data System (ADS)

    Tachihara, B. L.; Linder, C. A.; Holmes, R. M.

    2011-12-01

    In July 2011, Tachihara spent three weeks in the Siberian Arctic documenting The Polaris Project, an NSF-funded effort that brings together an international group of undergraduate students and research scientists to study Arctic systems. Using a combination of photography, video and interviews gathered during the field course, we produced a six-minute film focusing on the researchers' quest to track carbon as it moves from terrestrial upland areas into lakes, streams, rivers and eventually into the Arctic Ocean. The overall goal was to communicate the significance of Arctic science in the face of changing climate. Using a selection of clips from the 2011 video, we will discuss the advantages and challenges specific to using multimedia presentations to represent Arctic research, as well as science in general. The full video can be viewed on the Polaris website: http://www.thepolarisproject.org.

  7. The stratospheric pathway for Arctic impacts on midlatitude climate

    NASA Astrophysics Data System (ADS)

    Nakamura, Tetsu; Yamazaki, Koji; Iwamoto, Katsushi; Honda, Meiji; Miyoshi, Yasunobu; Ogawa, Yasunobu; Tomikawa, Yoshihiro; Ukita, Jinro

    2016-04-01

    Recent evidence from both observations and model simulations suggests that an Arctic sea ice reduction tends to cause a negative Arctic Oscillation (AO) phase with severe winter weather in the Northern Hemisphere, which is often preceded by weakening of the stratospheric polar vortex. Although this evidence hints at a stratospheric involvement in the Arctic-midlatitude climate linkage, the exact role of the stratosphere remains elusive. Here we show that tropospheric AO response to the Arctic sea ice reduction largely disappears when suppressing the stratospheric wave mean flow interactions in numerical experiments. The results confirm a crucial role of the stratosphere in the sea ice impacts on the midlatitudes by coupling between the stratospheric polar vortex and planetary-scale waves. Those results and consistency with observation-based evidence suggest that a recent Arctic sea ice loss is linked to midlatitudes extreme weather events associated with the negative AO phase.

  8. Changing Arctic ecosystems: resilience of caribou to climatic shifts in the Arctic

    USGS Publications Warehouse

    Gustine, David; Adams, Layne; Whalen, Mary; Pearce, John

    2014-01-01

    The U.S. Geological Survey (USGS) Changing Arctic Ecosystems (CAE) initiative strives to inform key resource management decisions for Arctic Alaska by providing scientific information and forecasts for current and future ecosystem response to a warming climate. Over the past 5 years, a focal area for the USGS CAE initiative has been the North Slope of Alaska. This region has experienced a warming trend over the past 60 years, yet the rate of change has been varied across the North Slope, leading scientists to question the future response and resilience of wildlife populations, such as caribou (Rangifer tarandus), that rely on tundra habitats for forage. Future changes in temperature and precipitation to coastal wet sedge and upland low shrub tundra are expected, with unknown consequences for caribou that rely on these plant communities for food. Understanding how future environmental change may affect caribou migration, nutrition, and reproduction is a focal question being addressed by the USGS CAE research. Results will inform management agencies in Alaska and people that rely on caribou for food.

  9. Food web dynamics affect Northeast Arctic cod recruitment

    PubMed Central

    Hjermann, Dag Ø; Bogstad, Bjarte; Eikeset, Anne Maria; Ottersen, Geir; Gjøsæter, Harald; Stenseth, Nils Chr

    2006-01-01

    Proper management of ecosystems requires an understanding of both the species interactions as well as the effect of climate variation. However, a common problem is that the available time-series are of different lengths. Here, we present a general approach for studying the dynamic structure of such interactions. Specifically, we analyse the recruitment of the world's largest cod stock, the Northeast Arctic cod. Studies based on data starting in the 1970–1980s indicate that this stock is affected by temperature through a variety of pathways. However, the value of such studies is somewhat limited by the fact that they are based on a quite specific ecological and climatic situation. Recently, this stock has consisted of fairly young fish and the spawning stock has consisted of relatively few age groups. In this study, we develop a model for the effect of capelin (the cod's main prey) and herring on cod recruitment since 1973. Based on this model, we analyse data on cod, herring and temperature going back to 1921 and find that food-web effects explain a significant part of the cod recruitment variation back to around 1950. PMID:17254990

  10. NuukBasic - Climate effects monitoring in low arctic Greenland

    NASA Astrophysics Data System (ADS)

    Aastrup, P.; Nymand, J.; Raundrup, K.; Tamstorf, M. P.; Forchhammer, M. C.; Schmidt, N. M.; Lauridsen, T. L.

    2009-12-01

    The climate effects research program in Zackenberg in high arctic Greenland got a counterpart in Nuuk in low arctic West Greenland in 2007. The programme NuukBasic is described and, for the first time, results will presented from several of the monitoring components (Table 1). In particular, we focus on changes in plant phenology, vegetation greenness, graded effects of UVB radiation and lake ecology. Results are compared and contrasted concurrent changes at the high arctic site Zackenberg in Northeast Greenland.Biological Monitoring elements in NuukBasis

  11. Sensitivity of the carbon cycle in the Arctic to climate change

    USGS Publications Warehouse

    McGuire, A. David; Anderson, Leif G.; Christensen, Torben R.; Dallimore, Scott; Guo, Laodong; Hayes, Daniel J.; Heimann, Martin; Lorenson, T.D.; Macdonald, Robie W.; Roulet, Nigel

    2009-01-01

    The recent warming in the Arctic is affecting a broad spectrum of physical, ecological, and human/cultural systems that may be irreversible on century time scales and have the potential to cause rapid changes in the earth system. The response of the carbon cycle of the Arctic to changes in climate is a major issue of global concern, yet there has not been a comprehensive review of the status of the contemporary carbon cycle of the Arctic and its response to climate change. This review is designed to clarify key uncertainties and vulnerabilities in the response of the carbon cycle of the Arctic to ongoing climatic change. While it is clear that there are substantial stocks of carbon in the Arctic, there are also significant uncertainties associated with the magnitude of organic matter stocks contained in permafrost and the storage of methane hydrates beneath both subterranean and submerged permafrost of the Arctic. In the context of the global carbon cycle, this review demonstrates that the Arctic plays an important role in the global dynamics of both CO2 and CH4. Studies suggest that the Arctic has been a sink for atmospheric CO2 of between 0 and 0.8 Pg C/yr in recent decades, which is between 0% and 25% of the global net land/ocean flux during the 1990s. The Arctic is a substantial source of CH4 to the atmosphere (between 32 and 112 Tg CH4/yr), primarily because of the large area of wetlands throughout the region. Analyses to date indicate that the sensitivity of the carbon cycle of the Arctic during the remainder of the 21st century is highly uncertain. To improve the capability to assess the sensitivity of the carbon cycle of the Arctic to projected climate change, we recommend that (1) integrated regional studies be conducted to link observations of carbon dynamics to the processes that are likely to influence those dynamics, and (2) the understanding gained from these integrated studies be incorporated into both uncoupled and fully coupled carbon–climate

  12. The Contribution to Arctic Climate Change from Countries in the Arctic Council

    NASA Astrophysics Data System (ADS)

    Schultz, T.; MacCracken, M. C.

    2013-12-01

    The conventional accounting frameworks for greenhouse gas (GHG) emissions used today, established under the Kyoto Protocol 25 years ago, exclude short lived climate pollutants (SLCPs), and do not include regional effects on the climate. However, advances in climate science now suggest that mitigation of SLCPs can reduce up to 50% of global warming by 2050. It has also become apparent that regions such as the Arctic have experienced a much greater degree of anthropogenic warming than the globe as a whole, and that efforts to slow this warming could benefit the larger effort to slow climate change around the globe. A draft standard for life cycle assessment (LCA), LEO-SCS-002, being developed under the American National Standards Institute process, has integrated the most recent climate science into a unified framework to account for emissions of all radiatively significant GHGs and SLCPs. This framework recognizes four distinct impacts to the oceans and climate caused by GHGs and SLCPs: Global Climate Change; Arctic Climate Change; Ocean Acidification; and Ocean Warming. The accounting for Arctic Climate Change, the subject of this poster, is based upon the Absolute Regional Temperature Potential, which considers the incremental change to the Arctic surface temperature resulting from an emission of a GHG or SLCP. Results are evaluated using units of mass of carbon dioxide equivalent (CO2e), which can be used by a broad array of stakeholders, including scientists, consumers, policy makers, and NGOs. This poster considers the contribution to Arctic Climate Change from emissions of GHGs and SLCPs from the eight member countries of the Arctic Council; the United States, Canada, Russia, Denmark, Finland, Iceland, Norway, and Sweden. Of this group of countries, the United States was the largest contributor to Arctic Climate Change in 2011, emitting 9600 MMT CO2e. This includes a gross warming of 11200 MMT CO2e (caused by GHGs, black and brown carbon, and warming effects

  13. Arctic Climate and Atmospheric Planetary Waves

    NASA Technical Reports Server (NTRS)

    Cavalieri, D. J.; Haekkinen, S.

    2000-01-01

    Analysis of a fifty-year record (1946-1995) of monthly-averaged sea level pressure data provides a link between the phases of planetary-scale sea level pressure waves and Arctic Ocean and ice variability. Results of this analysis show: (1) a breakdown of the dominant wave I pattern in the late 1960's, (2) shifts in the mean phase of waves 1 and 2 since this breakdown, (3) an eastward shift in the phases of both waves 1 and 2 during the years of simulated cyclonic Arctic Ocean circulation relative to their phases during the years of anticyclonic circulation, (4) a strong decadal variability of wave phase associated with simulated Arctic Ocean circulation changes. Finally, the Arctic atmospheric circulation patterns that emerge when waves 1 and 2 are in their extreme eastern and western positions suggest an alternative approach to determine significant forcing patterns of sea ice and high-latitude variability.

  14. Arctic Climate and Atmospheric Planetary Waves

    NASA Technical Reports Server (NTRS)

    Cavalieri, D. J.; Haekkinen, S.; Zukor, Dorothy J. (Technical Monitor)

    2001-01-01

    Analysis of a fifty-year record (1946-1995) of monthly-averaged sea level pressure data provides a link between the phases of planetary-scale sea level pressure waves and Arctic Ocean and ice variability. Results of this analysis show: (1) a breakdown of the dominant wave 1 pattern in the late 1960's, (2) shifts in the mean phase of waves 1 and 2 since this breakdown, (3) an eastward shift in the phases of both waves 1 and 2 during the years of simulated cyclonic Arctic Ocean circulation relative to their phases during the years of anticyclonic circulation, (4) a strong decadal variability of wave phase associated with simulated Arctic Ocean circulation changes. Finally, the Arctic atmospheric circulation patterns that emerge when waves 1 and 2 are in their extreme eastern and western positions suggest an alternative approach for determining significant forcing patterns of sea ice and high-latitude variability.

  15. Arctic climate change: Greenhouse warming unleashed

    NASA Astrophysics Data System (ADS)

    Mauritsen, Thorsten

    2016-04-01

    Human activity alters the atmospheric composition, which leads to global warming. Model simulations suggest that reductions in emission of sulfur dioxide from Europe since the 1970s could have unveiled rapid Arctic greenhouse gas warming.

  16. Pan-Arctic observations in GRENE Arctic Climate Change Research Project and its successor

    NASA Astrophysics Data System (ADS)

    Yamanouchi, Takashi

    2016-04-01

    We started a Japanese initiative - "Arctic Climate Change Research Project" - within the framework of the Green Network of Excellence (GRENE) Program, funded by the Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT), in 2011. This Project targeted understanding and forecasting "Rapid Change of the Arctic Climate System and its Global Influences." Four strategic research targets are set by the Ministry: 1. Understanding the mechanism of warming amplification in the Arctic; 2. Understanding the Arctic climate system for global climate and future change; 3. Evaluation of the impacts of Arctic change on the weather and climate in Japan, marine ecosystems and fisheries; 4. Projection of sea ice distribution and Arctic sea routes. Through a network of universities and institutions in Japan, this 5-year Project involves more than 300 scientists from 39 institutions and universities. The National Institute of Polar Research (NIPR) works as the core institute and The Japan Agency for Marine- Earth Science and Technology (JAMSTEC) joins as the supporting institute. There are 7 bottom up research themes approved: the atmosphere, terrestrial ecosystems, cryosphere, greenhouse gases, marine ecology and fisheries, sea ice and Arctic sea routes and climate modeling, among 22 applications. The Project will realize multi-disciplinal study of the Arctic region and connect to the projection of future Arctic and global climatic change by modeling. The project has been running since the beginning of 2011 and in those 5 years pan-Arctic observations have been carried out in many locations, such as Svalbard, Russian Siberia, Alaska, Canada, Greenland and the Arctic Ocean. In particular, 95 GHz cloud profiling radar in high precision was established at Ny-Ålesund, Svalbard, and intensive atmospheric observations were carried out in 2014 and 2015. In addition, the Arctic Ocean cruises by R/V "Mirai" (belonging to JAMSTEC) and other icebreakers belonging to other

  17. 77 FR 68102 - Programs and Research Projects Affecting the Arctic; 99th Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-15

    ...; ] ARCTIC RESEARCH COMMISSION Programs and Research Projects Affecting the Arctic; 99th Meeting Notice is hereby given that the U.S. Arctic Research Commission will hold its 99th meeting in Vancouver, British... programs and research projects affecting the Arctic. If you plan to attend this meeting, please notify...

  18. Communicating Climate and Ecosystem Change in the Arctic

    NASA Astrophysics Data System (ADS)

    Soreide, N. N.; Overland, J. E.; Calder, J. A.; Rodionov, S.

    2005-12-01

    There is an explosion of interest in Northern Hemisphere climate, highlighting the importance of recent changes in the Arctic on mid-latitude climate and its impact on marine and terrestrial ecosystems. Traditional sea ice and tundra dominated arctic ecosystems are being reorganizing into warmer sub-arctic ecosystem types. Over the previous two years we have developed a comprehensive, near real-time arctic change detection protocol to track physical and biological changes for presentation on the web: http://www.arctic.noaa.gov/detect. The effort provides a continuous update to the Arctic Climate Impact Assessment (ACIA) Report, released in November 2004. Principles for the protocol include an accessible narrative style, scientifically credible and objective indicators, notes multiple uses for the information, acknowledges uncertainties, and balances having too many indicators-which leads to information overload-and too few-which does not capture the complexity of the system. Screening criteria include concreteness, public awareness, being understandable, availability of historical time series, and sensitivity. The site provides sufficient information for an individual to make their own assessment regarding the balance of the evidence for tracking change. The product provides an overview, recent news, links to many arctic websites, and highlights climate, global impacts, land and marine ecosystems, and human consequences. Since its inception a year ago, it has averaged about 9000 hits an day on the web, and is a major information source as determined by Google search. The future direction focuses on understanding the causes for change. In spring 2005 we also presented a near real-time ecological and climatic surveillance website for the Bering Sea: www.beringclimate.noaa.gov. The site provides up-to-date information which ties northward shifts of fish, invertebrate and marine mammal populations to physical changes in the Arctic. This site is more technical than the

  19. Recent trends in energy flows through the Arctic climate system

    NASA Astrophysics Data System (ADS)

    Mayer, Michael; Haimberger, Leo

    2016-04-01

    While Arctic climate change can be diagnosed in many parameters, a comprehensive assessment of long-term changes and low frequency variability in the coupled Arctic energy budget still remains challenging due to the complex physical processes involved and the lack of observations. Here we draw on strongly improved observational capabilities of the past 15 years and employ observed radiative fluxes from CERES along with state-of-the-art atmospheric as well as coupled ocean-ice reanalyses to explore recent changes in energy flows through the Arctic climate system. Various estimates of ice volume and ocean heat content trends imply that the energy imbalance of the Arctic climate system was >1 Wm-2 during the 2000-2015 period, where most of the extra heat warmed the ocean and a comparatively small fraction was used to melt sea ice. The energy imbalance was partly fed by enhanced oceanic heat transports into the Arctic, especially in the mid 2000s. Seasonal trends of net radiation show a very clear signal of the ice-albedo feedback. Stronger radiative energy input during summer means increased seasonal oceanic heat uptake and accelerated sea ice melt. In return, lower minimum sea ice extent and higher SSTs lead to enhanced heat release from the ocean during fall season. These results are consistent with modeling studies finding an enhancement of the annual cycle of surface energy exchanges in a warming Arctic. Moreover, stronger heat fluxes from the ocean to the atmosphere in fall tend to warm the arctic boundary layer and reduce meridional temperature gradients, thereby reducing atmospheric energy transports into the polar cap. Although the observed results are a robust finding, extended high-quality datasets are needed to reliably separate trends from low frequency variability.

  20. Modelling the impacts of a dipole-like climatic state over the Arctic

    NASA Astrophysics Data System (ADS)

    Pasha Karami, Mehdi; de Vernal, Anne; Hu, Xianmin; Myers, Paul G.

    2015-04-01

    The Arctic dipole anomaly (ADA) features a pattern with opposite sea-level pressure anomalies over the Canadian Archipelago and the Barents Sea. Changes in the predominance of Arctic atmospheric circulation modes and the shift towards a dipole mode in the past decade played a role in the summer sea ice loss and sea ice-freshwater export from the Arctic to the North Atlantic. Reconstruction of sea ice cover variations during Holocene also suggests opposite anomalies in the Barents Sea versus either the western Arctic or the Fram Strait area similar to the ADA pattern. It is vital to study such physical processes that cause dramatic changes in the Arctic sea ice recalling the link between the ADA and the current climate change. Here we focus on the question of how a persistent ADA-like state affects the Arctic sea ice distribution and its outflow to the Atlantic Ocean. For this purpose, an eddy-permitting regional configuration of the NEMO coupled ocean/sea-ice model is used. The regional domain covers the Arctic Ocean and the Northern-Hemisphere Atlantic, with a horizontal resolution of 1/4 degree at the equator (ANHA4). For the present-day simulations, boundary conditions are obtained by taking the average over the years with a positive ADA and those with a negative ADA. In the Holocene scenario, global climate model data are used to force our regional model. To exclude the role of Bering Strait and the heat flux from the Pacific Ocean, we repeat the experiments with a closed Bering Strait since a nearly closed Bering configuration was possible for the Early Holocene. The model results are compared with the paleoclimate data from Arctic and subarctic seas.

  1. Experimental icing affects growth, mortality, and flowering in a high Arctic dwarf shrub.

    PubMed

    Milner, Jos M; Varpe, Øystein; van der Wal, René; Hansen, Brage Bremset

    2016-04-01

    Effects of climate change are predicted to be greatest at high latitudes, with more pronounced warming in winter than summer. Extreme mid-winter warm spells and heavy rain-on-snow events are already increasing in frequency in the Arctic, with implications for snow-pack and ground-ice formation. These may in turn affect key components of Arctic ecosystems. However, the fitness consequences of extreme winter weather events for tundra plants are not well understood, especially in the high Arctic. We simulated an extreme mid-winter rain-on-snow event at a field site in high Arctic Svalbard (78°N) by experimentally encasing tundra vegetation in ice. After the subsequent growing season, we measured the effects of icing on growth and fitness indices in the common tundra plant, Arctic bell-heather (Cassiope tetragona). The suitability of this species for retrospective growth analysis enabled us to compare shoot growth in pre and postmanipulation years in icing treatment and control plants, as well as shoot survival and flowering. Plants from icing treatment plots had higher shoot mortality and lower flowering success than controls. At the individual sample level, heavily flowering plants invested less in shoot growth than nonflowering plants, while shoot growth was positively related to the degree of shoot mortality. Therefore, contrary to expectation, undamaged shoots showed enhanced growth in ice treatment plants. This suggests that following damage, aboveground resources were allocated to the few remaining undamaged meristems. The enhanced shoot growth measured in our icing treatment plants has implications for climate studies based on retrospective analyses of Cassiope. As shoot growth in this species responds positively to summer warming, it also highlights a potentially complex interaction between summer and winter conditions. By documenting strong effects of icing on growth and reproduction of a widespread tundra plant, our study contributes to an understanding of

  2. A multivariate analysis of arctic climate in GCMs

    SciTech Connect

    McGinnis, D.L.; Crane, R.G. )

    1994-08-01

    A multivariate analysis of Arctic climate is performed comparing the observed climate with that simulated by four different global climate models (GCMs). The focus is on the patterns of temporal and spatial variability in several climate parameters (sea level pressure, temperature, specific humidity, and precipitation). There are broad similarities between the observed data and all the GCM climates. There are, however, several major differences. The observed data show the Arctic climate to be dominated by the summertime pattern of temperature and humidity, which is decoupled from the atmospheric circulation. The winter patterns explain less of the observed variance but show a much closer association between temperature and the large-scale circulation. The GCMs, in contrast, overemphasize the winter season and show more of a large-scale advective control on summertime temperature patterns. Possible reasons for these differences are suggested, and their implications for GCM climate studies are discussed. The shortcomings in the GCMs point to the need for improvements in boundary layer rendition, in the treatment of Arctic stratus, and in sea ice simulations through coupled ocean models and the inclusion of ice dynamics. 25 refs., 7 figs., 2 tabs.

  3. Interdisciplinary cooperation on impacts of climate change in the Arctic

    NASA Astrophysics Data System (ADS)

    Wardell, Lois; Chen, Linling; Strey, Sara

    2012-09-01

    Impact of Climate Change on Resources, Maritime Transport and Geopolitics in the Arctic and the Svalbard Area; Svalbard, Norway, 21-28 August 2011 Drastic changes in the Arctic climate directly relate to resource and transport development and complex geopolitical challenges in the Arctic. To encourage future interdisciplinary cooperation among political, social, and climate scientists, 30 early-career researchers from varied backgrounds—including climate change, resources, polar maritime transport, and geopolitics—assembled in Svalbard, Norway. Ola Johannessen, president of the Norwegian Scientific Academy of Polar Research, led this diverse group to highlight the importance of collaboration across disciplines for broadening the terms in which assessments are defined, thus collapsing distinctions between the physical and the human Arctic. He also highlighted the feasibility of conducting effective assessment exercises within short time frames. The group was also mentored by Willy Østreng, author of Science Without Boundaries: Interdisciplinarity in Research, Society, and Politics, who aided participants in understanding the process of interdisciplinary collaboration rather than creating an assemblage of discrete findings.

  4. Arctic Gas hydrate, Environment and Climate

    NASA Astrophysics Data System (ADS)

    Mienert, Jurgen; Andreassen, Karin; Bünz, Stefan; Carroll, JoLynn; Ferre, Benedicte; Knies, Jochen; Panieri, Giuliana; Rasmussen, Tine; Myhre, Cathrine Lund

    2015-04-01

    Arctic methane hydrate exists on land beneath permafrost regions and offshore in shelf and continental margins sediments. Methane or gas hydrate, an ice-like substrate, consists mainly of light hydrocarbons (mostly methane from biogenic sources but also ethane and propane from thermogenic sources) entrapped by a rigid cage of water molecules. The pressure created by the overlying water and sediments offshore stabilizes the CH4 in continental margins at a temperature range well above freezing point; consequently CH4 exists as methane ice beneath the seabed. Though the accurate volume of Arctic methane hydrate and thus the methane stored in hydrates throughout the Quaternary is still unknown it must be enormous if one considers the vast regions of Arctic continental shelves and margins as well as permafrost areas offshore and on land. Today's subseabed methane hydrate reservoirs are the remnants from the last ice age and remain elusive targets for both unconventional energy and as a natural methane emitter influencing ocean environments and ecosystems. It is still contentious at what rate Arctic warming may govern hydrate melting, and whether the methane ascending from the ocean floor through the hydrosphere reaches the atmosphere. As indicated by Greenland ice core records, the atmospheric methane concentration rose rapidly from ca. 500 ppb to ca. 750 ppb over a short time period of just 150 years at the termination of the younger Dryas period ca. 11600 years ago, but the dissociation of large quantities of methane hydrates on the ocean floor have not been documented yet (Brook et al., 2014 and references within). But with the major projected warming and sea ice melting trend (Knies et al., 2014) one may ask, for how long will CH4 stay trapped in methane hydrates if surface and deep-ocean water masses will warm and permafrost continuous to melt (Portnov et al. 2014). How much of the Arctic methane will be consumed by the micro- and macrofauna, how much will

  5. Arctic Shrub Growth Response to Climate Variation and Infrastructure Development on the North Slope of Alaska

    NASA Astrophysics Data System (ADS)

    Ackerman, D.; Finlay, J. C.; Griffin, D.

    2015-12-01

    Woody shrub growth in the arctic tundra is increasing on a circumpolar scale. Shrub expansion alters land-atmosphere carbon fluxes, nutrient cycling, and habitat structure. Despite these ecosystem effects, the drivers of shrub expansion have not been precisely established at the landscape scale. This project examined two proposed anthropogenic drivers: global climate change and local infrastructure development, a press disturbance that generates high levels of dust deposition. Effects of global change were studied using dendrochronology to establish a relationship between climate and annual growth in Betula and Salix shrubs growing in the Alaskan low Arctic. To understand the spatial heterogeneity of shrub expansion, this analysis was replicated in shrub populations across levels of landscape properties including soil moisture and substrate age. Effects of dust deposition on normalized difference vegetation index (NDVI) and photosynthetic rate were measured on transects up to 625 meters from the Dalton Highway. Dust deposition rates decreased exponentially with distance from road, matching previous models of road dust deposition. NDVI tracked deposition rates closely, but photosynthetic rates were not strongly affected by deposition. These results suggest that dust deposition may locally bias remote sensing measurements such as NDVI, without altering internal physiological processes such as photosynthesis in arctic shrubs. Distinguishing between the effects of landscape properties, climate, and disturbance will improve our predictions of the biogeochemical feedbacks of arctic shrub expansion, with potential application in climate change modeling.

  6. Emissions and climate forcing from global and Arctic fishing vessels

    NASA Astrophysics Data System (ADS)

    McKuin, Brandi; Campbell, J. Elliott

    2016-02-01

    Fishing vessels were recently found to be the largest source of black carbon ship emissions in the Arctic, suggesting that the fishing sector should be a focus for future studies. Here we developed a global and Arctic emissions inventory for fishing vessel emissions of short-lived and long-lived climate forcers based on data from a wide range of vessel sizes, fuel sulfur contents, engine types, and operational characteristics. We found that previous work generally underestimated emissions of short-lived climate forcers due to a failure to account for small fishing vessels as well as variability in emission factors. In particular, global black carbon emissions were underestimated by an order of magnitude. Furthermore, our order of magnitude estimate of the net climate effect from these fishing vessel emissions suggests that short-lived climate forcing may be particularly important in regions where fuel has a low sulfur content. These results have implications for proposed maritime policies and provide a foundation for future climate simulations to forecast climate change impacts in the Arctic.

  7. The fate of the Arctic seaweed Fucus distichus under climate change: an ecological niche modeling approach.

    PubMed

    Jueterbock, Alexander; Smolina, Irina; Coyer, James A; Hoarau, Galice

    2016-03-01

    Rising temperatures are predicted to melt all perennial ice cover in the Arctic by the end of this century, thus opening up suitable habitat for temperate and subarctic species. Canopy-forming seaweeds provide an ideal system to predict the potential impact of climate-change on rocky-shore ecosystems, given their direct dependence on temperature and their key role in the ecological system. Our primary objective was to predict the climate-change induced range-shift of Fucus distichus, the dominant canopy-forming macroalga in the Arctic and subarctic rocky intertidal. More specifically, we asked: which Arctic/subarctic and cold-temperate shores of the northern hemisphere will display the greatest distributional change of F. distichus and how will this affect niche overlap with seaweeds from temperate regions? We used the program MAXENT to develop correlative ecological niche models with dominant range-limiting factors and 169 occurrence records. Using three climate-change scenarios, we projected habitat suitability of F. distichus - and its niche overlap with three dominant temperate macroalgae - until year 2200. Maximum sea surface temperature was identified as the most important factor in limiting the fundamental niche of F. distichus. Rising temperatures were predicted to have low impact on the species' southern distribution limits, but to shift its northern distribution limits poleward into the high Arctic. In cold-temperate to subarctic regions, new areas of niche overlap were predicted between F. distichus and intertidal macroalgae immigrating from the south. While climate-change threatens intertidal seaweeds in warm-temperate regions, seaweed meadows will likely flourish in the Arctic intertidal. Although this enriches biodiversity and opens up new seaweed-harvesting grounds, it will also trigger unpredictable changes in the structure and functioning of the Arctic intertidal ecosystem. PMID:27087933

  8. Climate warming decreases the survival of the little auk (Alle alle), a high Arctic avian predator

    PubMed Central

    Hovinen, Johanna E H; Welcker, Jorg; Descamps, Sébastien; Strøm, Hallvard; Jerstad, Kurt; Berge, Jørgen; Steen, Harald

    2014-01-01

    Delayed maturity, low fecundity, and high adult survival are traits typical for species with a long-life expectancy. For such species, even a small change in adult survival can strongly affect the population dynamics and viability. We examined the effects of both regional and local climatic variability on adult survival of the little auk, a long-lived and numerous Arctic seabird species. We conducted a mark-resighting study for a period of 8 years (2006-2013) simultaneously at three little auk breeding sites that are influenced by the West Spitsbergen Current, which is the main carrier of warm, Atlantic water into the Arctic. We found that the survival of adult little auks was negatively correlated with both the North Atlantic Oscillation (NAO) index and local summer sea surface temperature (SST), with a time lag of 2 and 1 year, respectively. The effects of NAO and SST were likely mediated through a change in food quality and/or availability: (1) reproduction, growth, and development of Arctic Calanus copepods, the main prey of little auks, are negatively influenced by a reduction in sea ice, reduced ice algal production, and an earlier but shorter lasting spring bloom, all of which result from an increased NAO; (2) a high sea surface temperature shortens the reproductive period of Arctic Calanus, decreasing the number of eggs produced. A synchronous variation in survival rates at the different colonies indicates that climatic forcing was similar throughout the study area. Our findings suggest that a predicted warmer climate in the Arctic will negatively affect the population dynamics of the little auk, a high Arctic avian predator. PMID:25247069

  9. Influence of climate model variability on projected Arctic shipping futures

    NASA Astrophysics Data System (ADS)

    Stephenson, Scott R.; Smith, Laurence C.

    2015-11-01

    Though climate models exhibit broadly similar agreement on key long-term trends, they have significant temporal and spatial differences due to intermodel variability. Such variability should be considered when using climate models to project the future marine Arctic. Here we present multiple scenarios of 21st-century Arctic marine access as driven by sea ice output from 10 CMIP5 models known to represent well the historical trend and climatology of Arctic sea ice. Optimal vessel transits from North America and Europe to the Bering Strait are estimated for two periods representing early-century (2011-2035) and mid-century (2036-2060) conditions under two forcing scenarios (RCP 4.5/8.5), assuming Polar Class 6 and open-water vessels with medium and no ice-breaking capability, respectively. Results illustrate that projected shipping viability of the Northern Sea Route (NSR) and Northwest Passage (NWP) depends critically on model choice. The eastern Arctic will remain the most reliably accessible marine space for trans-Arctic shipping by mid-century, while outcomes for the NWP are particularly model-dependent. Omitting three models (GFDL-CM3, MIROC-ESM-CHEM, and MPI-ESM-MR), our results would indicate minimal NWP potential even for routes from North America. Furthermore, the relative importance of the NSR will diminish over time as the number of viable central Arctic routes increases gradually toward mid-century. Compared to vessel class, climate forcing plays a minor role. These findings reveal the importance of model choice in devising projections for strategic planning by governments, environmental agencies, and the global maritime industry.

  10. The Arctic as a test case for an assessment of climate impacts on national security.

    SciTech Connect

    Taylor, Mark A.; Zak, Bernard Daniel; Backus, George A.; Ivey, Mark D.; Boslough, Mark Bruce Elrick

    2008-11-01

    The Arctic region is rapidly changing in a way that will affect the rest of the world. Parts of Alaska, western Canada, and Siberia are currently warming at twice the global rate. This warming trend is accelerating permafrost deterioration, coastal erosion, snow and ice loss, and other changes that are a direct consequence of climate change. Climatologists have long understood that changes in the Arctic would be faster and more intense than elsewhere on the planet, but the degree and speed of the changes were underestimated compared to recent observations. Policy makers have not yet had time to examine the latest evidence or appreciate the nature of the consequences. Thus, the abruptness and severity of an unfolding Arctic climate crisis has not been incorporated into long-range planning. The purpose of this report is to briefly review the physical basis for global climate change and Arctic amplification, summarize the ongoing observations, discuss the potential consequences, explain the need for an objective risk assessment, develop scenarios for future change, review existing modeling capabilities and the need for better regional models, and finally to make recommendations for Sandia's future role in preparing our leaders to deal with impacts of Arctic climate change on national security. Accurate and credible regional-scale climate models are still several years in the future, and those models are essential for estimating climate impacts around the globe. This study demonstrates how a scenario-based method may be used to give insights into climate impacts on a regional scale and possible mitigation. Because of our experience in the Arctic and widespread recognition of the Arctic's importance in the Earth climate system we chose the Arctic as a test case for an assessment of climate impacts on national security. Sandia can make a swift and significant contribution by applying modeling and simulation tools with internal collaborations as well as with outside

  11. Climate-driven regime shifts in Arctic marine benthos.

    PubMed

    Kortsch, Susanne; Primicerio, Raul; Beuchel, Frank; Renaud, Paul E; Rodrigues, João; Lønne, Ole Jørgen; Gulliksen, Bjørn

    2012-08-28

    Climate warming can trigger abrupt ecosystem changes in the Arctic. Despite the considerable interest in characterizing and understanding the ecological impact of rapid climate warming in the Arctic, few long time series exist that allow addressing these research goals. During a 30-y period (1980-2010) of gradually increasing seawater temperature and decreasing sea ice cover in Svalbard, we document rapid and extensive structural changes in the rocky-bottom communities of two Arctic fjords. The most striking component of the benthic reorganization was an abrupt fivefold increase in macroalgal cover in 1995 in Kongsfjord and an eightfold increase in 2000 in Smeerenburgfjord. Simultaneous changes in the abundance of benthic invertebrates suggest that the macroalgae played a key structuring role in these communities. The abrupt, substantial, and persistent nature of the changes observed is indicative of a climate-driven ecological regime shift. The ecological processes thought to drive the observed regime shifts are likely to promote the borealization of these Arctic marine communities in the coming years. PMID:22891319

  12. Climate-driven regime shifts in Arctic marine benthos

    PubMed Central

    Kortsch, Susanne; Primicerio, Raul; Beuchel, Frank; Renaud, Paul E.; Rodrigues, João; Lønne, Ole Jørgen; Gulliksen, Bjørn

    2012-01-01

    Climate warming can trigger abrupt ecosystem changes in the Arctic. Despite the considerable interest in characterizing and understanding the ecological impact of rapid climate warming in the Arctic, few long time series exist that allow addressing these research goals. During a 30-y period (1980–2010) of gradually increasing seawater temperature and decreasing sea ice cover in Svalbard, we document rapid and extensive structural changes in the rocky-bottom communities of two Arctic fjords. The most striking component of the benthic reorganization was an abrupt fivefold increase in macroalgal cover in 1995 in Kongsfjord and an eightfold increase in 2000 in Smeerenburgfjord. Simultaneous changes in the abundance of benthic invertebrates suggest that the macroalgae played a key structuring role in these communities. The abrupt, substantial, and persistent nature of the changes observed is indicative of a climate-driven ecological regime shift. The ecological processes thought to drive the observed regime shifts are likely to promote the borealization of these Arctic marine communities in the coming years. PMID:22891319

  13. Climate change and sexual size dimorphism in an Arctic spider.

    PubMed

    Høye, Toke Thomas; Hammel, Jörg U; Fuchs, Thomas; Toft, Søren

    2009-08-23

    Climate change is advancing the onset of the growing season and this is happening at a particularly fast rate in the High Arctic. However, in most species the relative fitness implications for males and females remain elusive. Here, we present data on 10 successive cohorts of the wolf spider Pardosa glacialis from Zackenberg in High-Arctic, northeast Greenland. We found marked inter-annual variation in adult body size (carapace width) and this variation was greater in females than in males. Earlier snowmelt during both years of its biennial maturation resulted in larger adult body sizes and a skew towards positive sexual size dimorphism (females bigger than males). These results illustrate the pervasive influence of climate on key life-history traits and indicate that male and female responses to climate should be investigated separately whenever possible. PMID:19435831

  14. Climate change and sexual size dimorphism in an Arctic spider

    PubMed Central

    Høye, Toke Thomas; Hammel, Jörg U.; Fuchs, Thomas; Toft, Søren

    2009-01-01

    Climate change is advancing the onset of the growing season and this is happening at a particularly fast rate in the High Arctic. However, in most species the relative fitness implications for males and females remain elusive. Here, we present data on 10 successive cohorts of the wolf spider Pardosa glacialis from Zackenberg in High-Arctic, northeast Greenland. We found marked inter-annual variation in adult body size (carapace width) and this variation was greater in females than in males. Earlier snowmelt during both years of its biennial maturation resulted in larger adult body sizes and a skew towards positive sexual size dimorphism (females bigger than males). These results illustrate the pervasive influence of climate on key life-history traits and indicate that male and female responses to climate should be investigated separately whenever possible. PMID:19435831

  15. Losing ground: past history and future fate of Arctic small mammals in a changing climate.

    PubMed

    Prost, Stefan; Guralnick, Robert P; Waltari, Eric; Fedorov, Vadim B; Kuzmina, Elena; Smirnov, Nickolay; van Kolfschoten, Thijs; Hofreiter, Michael; Vrieling, Klaas

    2013-06-01

    According to the IPCC, the global average temperature is likely to increase by 1.4-5.8 °C over the period from 1990 to 2100. In Polar regions, the magnitude of such climatic changes is even larger than in temperate and tropical biomes. This amplified response is particularly worrisome given that the so-far moderate warming is already impacting Arctic ecosystems. Predicting species responses to rapid warming in the near future can be informed by investigating past responses, as, like the rest of the planet, the Arctic experienced recurrent cycles of temperature increase and decrease (glacial-interglacial changes) in the past. In this study, we compare the response of two important prey species of the Arctic ecosystem, the collared lemming and the narrow-skulled vole, to Late Quaternary climate change. Using ancient DNA and Ecological Niche Modeling (ENM), we show that the two species, which occupy similar, but not identical ecological niches, show markedly different responses to climatic and environmental changes within broadly similar habitats. We empirically demonstrate, utilizing coalescent model-testing approaches, that collared lemming populations decreased substantially after the Last Glacial Maximum; a result consistent with distributional loss over the same period based on ENM results. Given this strong association, we projected the current niche onto future climate conditions based on IPCC 4.0 scenarios, and forecast accelerating loss of habitat along southern range boundaries with likely associated demographic consequences. Narrow-skulled vole distribution and demography, by contrast, was only moderately impacted by past climatic changes, but predicted future changes may begin to affect their current western range boundaries. Our work, founded on multiple lines of evidence suggests a future of rapidly geographically shifting Arctic small mammal prey communities, some of whom are on the edge of existence, and whose fate may have ramifications for the

  16. The seasonal cycle of the Arctic Ocean under climate change

    NASA Astrophysics Data System (ADS)

    Carton, James A.; Ding, Yanni; Arrigo, Kevin R.

    2015-09-01

    The seasonal cycle of Arctic Ocean temperature is weak due to the insulating and light-scattering effects of sea ice cover and the moderating influence of the seasonal storage and release of heat through ice melting and freezing. The retreat of sea ice and other changes in recent decades is already warming surface air temperatures in winter. These meteorological changes raise the question of how the seasonal cycle of the ocean may change. Here we present results from coupled climate model simulations showing that the loss of sea ice will dramatically increase the amplitude of the seasonal cycle of sea surface temperature in the Arctic Ocean. Depending on the rate of growth of atmospheric greenhouse gases, the seasonal range in Arctic sea surface temperature may exceed 10°C by year 2300, greatly increasing the stratification of the summer mixed layer.

  17. Food and water security in a changing arctic climate

    NASA Astrophysics Data System (ADS)

    White, Daniel M.; Gerlach, S. Craig; Loring, Philip; Tidwell, Amy C.; Chambers, Molly C.

    2007-10-01

    In the Arctic, permafrost extends up to 500 m below the ground surface, and it is generally just the top metre that thaws in summer. Lakes, rivers, and wetlands on the arctic landscape are normally not connected with groundwater in the same way that they are in temperate regions. When the surface is frozen in winter, only lakes deeper than 2 m and rivers with significant flow retain liquid water. Surface water is largely abundant in summer, when it serves as a breeding ground for fish, birds, and mammals. In winter, many mammals and birds are forced to migrate out of the Arctic. Fish must seek out lakes or rivers deep enough to provide good overwintering habitat. Humans in the Arctic rely on surface water in many ways. Surface water meets domestic needs such as drinking, cooking, and cleaning as well as subsistence and industrial demands. Indigenous communities depend on sea ice and waterways for transportation across the landscape and access to traditional country foods. The minerals, mining, and oil and gas industries also use large quantities of surface water during winter to build ice roads and maintain infrastructure. As demand for this limited, but heavily-relied-upon resource continues to increase, it is now more critical than ever to understand the impacts of climate change on food and water security in the Arctic.

  18. Reconstructing the Climate and Ecology of an Arctic Pliocene Forest

    NASA Astrophysics Data System (ADS)

    Rybczynski, N.; Ballantyne, A.; Csank, A.; Matheus, P.

    2006-12-01

    Instrumental records reveal that the current rate of arctic warming greatly exceeds mean global warming. However, arctic temperatures during the Pliocene were considerably warmer than present, making it an excellent time period for investigating potential consequences of current warming trends. Pliocene-aged (4 to 5 Ma) peat deposits from Ellesmere Island are characterized by a remarkable fossil assemblage including 15 vertebrate taxa, 90 plant taxa and 101 invertebrate taxa. Among the fossils are well-preserved samples of an extinct larch (Larix groenlandii), which have been exploited as an archive of paleoclimatic information. Analysis of annual ring widths and oxygen isotopes suggest that Pliocene temperatures were 14.2 ° C warmer than today (-5.5 \\mp 1.9 ° C). Furthermore, temporal patterns in isotopic variability suggest that modes of variability that dominate modern arctic climates, such as the NAO, were also operating during the Pliocene. Isotopic analysis of fossil bone material may provide insight into the structure of past arctic ecosystems. Preliminary data suggest that carbon and nitrogen isotopes extracted from the collagen of fossil bone may provide a powerful new tool for investigating the response of arctic ecosystems to previously warm intervals in Earth's History.

  19. Collaborative Research: Towards Advanced Understanding and Predictive Capability of Climate Change in the Arctic using a High-Resolution Regional Arctic Climate System Model

    SciTech Connect

    Lettenmaier, Dennis P

    2013-04-08

    Primary activities are reported in these areas: climate system component studies via one-way coupling experiments; development of the Regional Arctic Climate System Model (RACM); and physical feedback studies focusing on changes in Arctic sea ice using the fully coupled model.

  20. Quantitative Climate Reconstruction Based On Pollen Data From Russian Arctic

    NASA Astrophysics Data System (ADS)

    Tarasov, P. E.; Andreev, A. A.; Hubberten, H.-W.

    Three different statistical approaches have been tested to get quantitative reconstruc- tion of the Late Quaternary climate fluctuations in the Russian Arctic using surface pollen data set from the northern Eurasia. An information-statistical method (Kli- manov, 1984) is based on the statistical correlations between the total pollen and spore abundance, as well as relative values of 14 most common tree and shrub pollen taxa. Over 800 recent pollen spectra from 220 sites across the northern Eurasia were used to worked out the method. It has been applied to the fossil pollen records from the Rus- sian Arctic (e.g. Andreev and Klimanov, 2000). However, we found that it has a clear limitation in reconstruction of climate from spectra with low percentages of arboreal pollen. A plant functional type (PFT) method gives better results in reconstruction of modern climate in the forest-tundra and tundra zone (Tarasov et al., 1999). However, transfer functions between modern PFT scores and climate were also derived from the data set with a limited number of Russian Arctic pollen spectra. A best modern ana- logues method (Guiot, 1990) have been applied to the recently updated modern pollen data set, including over 1100 pollen spectra from the areas of the former USSR and Mongolia. Totally, 77 arboreal and non-arboreal pollen taxa were included in the anal- ysis. Modern climate variables at the pollen sampling sites have been calculated from the climate database with precise topography (W. Cramer, pers. comm.). We found that the mean July temperature and the sum of the mean daily temperatures above 5zC (growing-degree-days) can be reconstructed in the Russian Arctic with high accuracy. However, pollen spectra from Russian Arctic do not show a clear response to changes in the mean January temperature and in moisture index. Among the other tested vari- ables annual precipitation and runoff (annual precipitation minus evaporation) were reconstructed from the modern pollen spectra

  1. Dynamics of a recovering Arctic bird population: the importance of climate, density dependence, and site quality.

    PubMed

    Bruggeman, Jason E; Swem, Ted; Andersen, David E; Kennedy, Patricia L; Nigro, Debora

    2015-10-01

    Intrinsic and extrinsic factors affect vital rates and population-level processes, and understanding these factors is paramount to devising successful management plans for wildlife species. For example, birds time migration in response, in part, to local and broadscale climate fluctuations to initiate breeding upon arrival to nesting territories, and prolonged inclement weather early in the breeding season can inhibit egg-laying and reduce productivity. Also, density-dependent regulation occurs in raptor populations, as territory size is related to resource availability. Arctic Peregrine Falcons (Falco peregrinus tundrius; hereafter Arctic peregrine) have a limited and northern breeding distribution, including the Colville River Special Area (CRSA) in the National Petroleum Reserve-Alaska, USA. We quantified influences of climate, topography, nest productivity, prey habitat, density dependence, and interspecific competition affecting Arctic peregrines in the CRSA by applying the Dail-Madsen model to estimate abundance and vital rates of adults on nesting cliffs from 1981 through 2002. Arctic peregrine abundance increased throughout the 1980s, which spanned the population's recovery from DDT-induced reproductive failure, until exhibiting a stationary trend in the 1990s. Apparent survival rate (i.e., emigration; death) was negatively correlated with the number of adult Arctic peregrines on the cliff the previous year, suggesting effects of density-dependent population regulation. Apparent survival and arrival rates (i.e., immigration; recruitment) were higher during years with earlier snowmelt and milder winters, and apparent survival was positively correlated with nesting season maximum daily temperature. Arrival rate was positively correlated with average Arctic peregrine productivity along a cliff segment from the previous year and initial abundance was positively correlated with cliff height. Higher cliffs with documented higher productivity (presumably

  2. The state of climate change adaptation in the Arctic

    NASA Astrophysics Data System (ADS)

    Ford, James D.; McDowell, Graham; Jones, Julie

    2014-10-01

    The Arctic climate is rapidly changing, with wide ranging impacts on natural and social systems. A variety of adaptation policies, programs and practices have been adopted to this end, yet our understanding of if, how, and where adaptation is occurring is limited. In response, this paper develops a systematic approach to characterize the current state of adaptation in the Arctic. Using reported adaptations in the English language peer reviewed literature as our data source, we document 157 discrete adaptation initiatives between 2003 and 2013. Results indicate large variations in adaptation by region and sector, dominated by reporting from North America, particularly with regards to subsistence harvesting by Inuit communities. Few adaptations were documented in the European and Russian Arctic, or have a focus on the business and economy, or infrastructure sectors. Adaptations are being motivated primarily by the combination of climatic and non-climatic factors, have a strong emphasis on reducing current vulnerability involving incremental changes to existing risk management processes, and are primarily initiated and led at the individual/community level. There is limited evidence of trans-boundary adaptations or initiatives considering potential cross-scale/sector impacts.

  3. Arctic Hydrology and the role of feedbacks in the climate system (Invited)

    NASA Astrophysics Data System (ADS)

    Hinzman, L. D.

    2009-12-01

    The effects of a warming climate on the terrestrial regions of the Arctic are already quite apparent and impacts to the hydrologic system are also quite evident. The broadest impacts to the terrestrial arctic regions will result through consequent effects of changing permafrost structure and extent. As the climate differentially warms in summer and winter, the permafrost will become warmer, the active layer (the layer of soil above the permafrost that annually experiences freeze and thaw) will become thicker, the lower boundary of permafrost will become shallower and permafrost extent will decrease in area. These simple structural changes will affect every aspect of the surface water and energy balances and local ecology. Surface moisture and surface temperature are the main driving variables in local terrestrial and atmospheric linkages. Surface temperature is the linchpin in energy fluxes since it links atmospheric thermal gradients, forcing convective heat transfer, with the subsurface thermal gradients, driving conductive heat transfer. Soil moisture exerts a strong influence upon energy fluxes through controls on evaporative heat flux, phase change in thawing of permafrost, and indirect effects on thermal conductivity. In order to understand and predict ecosystem responses to a changing climate and the resultant feedbacks, it is critical to quantify the dynamic interactions of soil moisture and temperature with changes in permafrost as a function of climatic processes, landscape type, and vegetation. In future climate scenarios, the Arctic is expected to be warmer, and experience greater precipitation. With the lengthening of the summer season, however, more of this precipitation will occur as rain. The periods of potential evaporation, and transpiration will also increase. Oddly enough, even now, the Arctic may be considered a desert. The vast wetlands that cover large portions of Alaska, Canada and Siberia exist because permafrost prevents soil moisture and

  4. Recent and Predicted Changes in Pan-Arctic Vegetation Properties and Their Climate Feedback Implications

    NASA Astrophysics Data System (ADS)

    Goetz, S. J.

    2014-12-01

    Arctic surface air temperatures have risen at approximately twice the global rate, generating a range of ecosystem responses and associated climate feedbacks. Well-documented examples include changes in vegetation productivity, fire disturbance, the expansion of woody shrubs into tundra, and associated changes in surface albedo and net surface shortwave radiative forcing. I will briefly review these and other changes across the pan-Arctic domain using a combination of field measurements and satellite remote sensing observations. I will examine the evidence for change that has already occurred and also discuss predictions of likely future ecosystem responses under different climate change scenarios. I will identify research and data needs that would help to resolve discrepancies and disparities that have been reported. In particular I will address the current potential and limitations of vegetation distribution models and the data sets that inform them. Notably, model predictions indicate rapid shifts to larger woody growth-forms, rapid colonization due to long-distance dispersal, and favorable conditions for recruitment following disturbances like tundra fire and permafrost degradation. Future albedo, evapotranspiration and aboveground biomass will change with the redistribution of Arctic vegetation, and the climate feedbacks of these ecosystem changes can be significant. Albedo and net surface shortwave radiation changes will dominate the influence on climate, largely due to the snow masking effects of taller vegetation. The carbon implications of ecosystem change will likely be dominated by processes that influence permafrost thaw vulnerability, but predictions also indicate that vegetation in the Arctic will affect climate primarily as a biophysical medium (i.e. via albedo change). As with thawing permafrost, predicted vegetation changes would exacerbate currently amplified rates of warming. New research efforts focused on the Arctic will address the research

  5. Development of Exhibit on Arctic Climate Change Called The Arctic: A Friend Acting Strangely Exhibition

    SciTech Connect

    Stauffer, Barbara W.

    2006-04-01

    The exhibition, The Arctic: A Friend Acting Strangely, was developed at the Smithsonian Institution’s National Museum of Natural History (NMNH) as a part of the museum’s Forces of Change exhibit series on global change. It opened to the public in Spring 2006, in conjunction with another Forces of Change exhibit on the Earth’s atmosphere called Change Is in the Air. The exhibit was a 2000 square-foot presentation that explored the forces and consequences of the changing Arctic as documented by scientists and native residents alike. Native peoples of the Arctic have always lived with year-to-year fluctuations in weather and ice conditions. In recent decades, they have witnessed that the climate has become unpredictable, the land and sea unfamiliar. An elder in Arctic Canada recently described the weather as uggianaqtuq —an Inuit word that can suggest strange, unexpected behavior, sometimes described as that of “a friend acting strangely.” Scientists too have been documenting dramatic changes in the Arctic. Air temperatures have warmed over most—though not all—of the Arctic since the 1950s; Arctic precipitation may have increased by as much as 8%; seasonal melting of the Greenland Ice Sheet has increased on average by 16% since 1979; polar-orbiting satellites have measured a 15¬–20% decline in sea ice extent since the 1970s; aircraft reconnaissance and ship observations show a steady decrease in sea ice since the 1950s. In response to this warming, plant distributions have begun to shift and animals are changing their migration routes. Some of these changes may have beneficial effects while others may bring hardship or have costly implications. And, many scientists consider arctic change to be a ‘bell-weather’ for large-scale changes in other regions of the world. The exhibition included text, photos artifacts, hands-on interactives and other exhibitry that illustrated the changes being documented by indigenous people and scientists alike.

  6. Rising to the Challenge of Climate Impact Assessment in the Arctic (Invited)

    NASA Astrophysics Data System (ADS)

    Hinzman, L. D.

    2013-12-01

    The environmental changes ongoing in Arctic Regions have clearly demonstrated the climate is changing however assessing and predicting the impacts upon the physical and biological systems remains an important research challenge. To truly understand the evolution of the environment in response to a warming climate, we cannot investigate single components in isolation. We must change our perspective to include the dynamic linkages and feedbacks among system components, including physical and biological processes and in some cases societal interactions. The land areas of the Arctic are changing rapidly. The permafrost is degrading, lakes are draining, soils are getting drier, plant and animal species are migrating northward, snow is melting earlier and returning later. The marine system is also experiencing marked changes, most notably loss of sea ice, warming of deeper layers, changes in cloudiness and weather, acidification and migration of species. Trends of decreasing sea ice and increased open-water fetch, combined with warming air and ground temperatures, result in higher wave energy, increased seasonal thaw, and accelerated coastal retreat along large parts of circum-Arctic coast. All of these changes are having a significant impact upon local environment, but these changes are occurring over such a large area, they are beginning to affect regional and perhaps even global climate. We will not be able accurately forecast the impacts of changing climate conditions until we can accurately incorporate the processes of those dynamics in the integrated system.

  7. Influence of the physical terrestrial Arctic in the eco-climate system.

    PubMed

    Saito, Kazuyuki; Zhang, Tingjun; Yang, Daqing; Marchenko, Sergei; Barry, Roger G; Romanovsky, Vladimir; Hinzman, Larry

    2013-12-01

    This synthesis paper provides a summary of the major components of the physical terrestrial Arctic and the influences of their changes upon the larger eco-climate system. Foci here are snow cover, permafrost, and land hydrology. During the last century, snow cover duration has shortened in a large portion of the circum-Arctic, mainly because of its early northward retreat in spring due to warming. Winter precipitation has generally increased, resulting in an increase in maximum snow depth over large areas. This is consistent with the increase in river discharge over large Russian watersheds. Soil temperature has also increased, and the active layer has deepened in most of the permafrost regions, whereas thinning of the seasonally frozen layer has been observed in areas not underlain by permafrost. These active components are mutually interrelated, conditioned by ambient micro- to landscape-level topography and local surface and subsurface conditions, and they are closely related with vegetation and ecology, as evidenced by evolution in the late Quaternary. Further, we provide examples and arguments for discussions on the pathways through which changes in the Arctic terrestrial system can affect or propagate to remote areas beyond the Arctic, reaching to the extratropics in the larger climate system. These considerations include dynamical and thermodynamical responses and feedbacks,'modification of hemisphere-scale atmospheric circulation associated with troposphere-stratosphere couplings, and moisture intrusion at a continental scale. PMID:24555309

  8. Arctic Ocean freshwater as a trigger for abrupt climate change

    NASA Astrophysics Data System (ADS)

    Bradley, Raymond; Condron, Alan; Coletti, Anthony

    2016-04-01

    The cause of the Younger Dryas cooling remains unresolved despite decades of debate. Current arguments focus on either freshwater from Glacial Lake Agassiz drainage through the St Lawrence or the MacKenzie river systems. High resolution ocean modeling suggests that freshwater delivered to the North Atlantic from the Arctic Ocean through Fram Strait would have had more of an impact on Atlantic Meridional Overturning Circulation (AMOC) than freshwater from the St Lawrence. This has been interpreted as an argument for a MacKenzie River /Lake Agassiz freshwater source. However, it is important to note that although the modeling identifies Fram Strait as the optimum location for delivery of freshwater to disrupt the AMOC, this does not mean the freshwater source came from Lake Agassiz. Another potential source of freshwater is the Arctic Ocean ice cover itself. During the LGM, ice cover was extremely thick - many tens of meters in the Canada Basin (at least), resulting in a hiatus in sediment deposition there. Extreme ice thickness was related to a stagnant circulation, very low temperatures and continuous accumulation of snow on top of a base of sea-ice. This resulted in a large accumulation of freshwater in the Arctic Basin. As sea-level rose and a more modern circulation regime became established in the Arctic, this freshwater was released from the Arctic Ocean through Fram Strait, leading to extensive sea-ice formation in the North Atlantic (Greenland Sea) and a major reduction in the AMOC. Here we present new model results and a review of the paleoceanographic evidence to support this hypothesis. The bottom line is that the Arctic Ocean was likely a major player in causing abrupt climate change in the past, via its influence on the AMOC. Although we focus here on the Younger Dryas, the Arctic Ocean has been repeatedly isolated from the world ocean during glacial periods of the past. When these periods of isolation ended, it is probable that there were significant

  9. Will Arctic ground squirrels impede or accelerate climate-induced vegetation changes to the Arctic tundra?

    NASA Astrophysics Data System (ADS)

    Dalton, J.; Flower, C. E.; Brown, J.; Gonzalez-Meler, M. A.; Whelan, C.

    2014-12-01

    Considerable attention has been given to the climate feedbacks associated with predicted vegetation shifts in the Arctic tundra in response to global environmental change. However, little is known regarding the extent to which consumers can facilitate or respond to shrub expansion. Arctic ground squirrels, the largest and most northern ground squirrel, are abundant and widespread throughout the North American tundra. Their broad diet of seeds, flowers, herbage, bird's eggs and meat speaks to the need to breed, feed, and fatten in a span of some 12-16 weeks that separate their 8-9 month bouts of hibernation with the potential consequence to impact ecosystem dynamics. Therefore Arctic ground squirrels are a good candidate to evaluate whether consumers are mere responders (bottom-up effects) or drivers (top-down) of the observed and predicted vegetation changes. As a start towards this question, we measured the foraging intensity (giving-up densities) of Arctic ground squirrels in experimental food patches within which the squirrels experience diminishing returns as they seek the raisins and peanuts that we provided at the Toolik Lake field station in northern Alaska. If the squirrels show their highest feeding intensity in the shrubs, they may impede vegetation shifts by slowing the establishment and expansion of shrubs in the tundra. Conversely, if they show their lowest feeding intensity within shrub dominated areas, they may accelerate vegetation shifts. We found neither. Feeding intensity varied most among transects and times of day, and least along a tundra-to-shrub vegetation gradient. This suggests that the impacts of squirrels will be heterogeneous - in places responders and in others drivers. We should not be surprised then to see patches of accelerated and impeded vegetation changes in the tundra ecosystem. Some of these patterns may be predictable from the foraging behavior of Arctic ground squirrels.

  10. The effects of climate changes on soil methane oxidation in a dry Arctic tundra

    NASA Astrophysics Data System (ADS)

    D'Imperio, Ludovica

    2014-05-01

    The effects of climate changes on soil methane oxidation in a dry Arctic tundra. Ludovica D'Imperio1, Anders Michelsen1, Christian J. Jørgensen1, Bo Elberling1 1Center for Permafrost (CENPERM), Department of Geosciences and Natural Resource Management, University of Copenhagen, Denmark At Northern latitudes climatic changes are predicted to be most pronounced resulting in increasing active layer depth and changes in growing season length, vegetation cover and nutrient cycling. As a consequence of increased temperature, large stocks of carbon stored in the permafrost-affected soils could become available for microbial transformations and under anoxic conditions result in increasing methane production affecting net methane (CH4) budget. Arctic tundra soils also serves as an important sink of atmospheric CH4 by microbial oxidation under aerobic conditions. While several process studies have documented the mechanisms behind both production and emissions of CH4 in arctic ecosystems, an important knowledge gap exists with respect to the in situ dynamics of microbial-driven uptake of CH4 in arctic dry lands which may be enhanced as a consequence of global warming and thereby counterbalancing CH4 emissions from Arctic wetlands. In-situ methane measurements were made in a dry Arctic tundra in Disko Island, Western Greenland, during the summer 2013 to assess the role of seasonal and inter-annual variations in temperatures and snow cover. The experimental set-up included snow fences installed in 2012, allowed investigations of the emissions of GHGs from soil under increased winter snow deposition and ambient field conditions. The soil fluxes of CH4 and CO2 were measured using closed chambers in manipulated plots with increased summer temperatures and shrub removal with or without increased winter precipitation. At the control plots, the averaged seasonal CH4 oxidation rates ranged between -0.05 mg CH4 m-2 hr-1 (end of August) and -0.32 mg CH4 m-2 hr-1 (end of June). In the

  11. Impact of Atlantic Meridional Overturning Circulation (AMOC) Variability on Arctic Climate

    NASA Astrophysics Data System (ADS)

    Mahajan, S.; Zhang, R.; Delworth, T. L.

    2009-12-01

    Observations show a rapid decline of Arctic sea-ice extent and thickness, and a rapid warming in Arctic surface air temperatures (SAT) in the past decade. Recent observational studies confirm the amplification of SAT anomalies over the Arctic region, as previously suggested by several modeling studies. While climate model projections clearly show that increasing anthropogenic greenhouse gases lead to a warming trend over the Arctic, a recent study finds multidecadal variations of Arctic climate that are strongly correlated with the Atlantic Multidecadal Oscillation (AMO). The AMOC is often thought to be a major source of decadal/multidecadal variability in the climate system, and contributes to the observed AMO. The focus of this study is to evaluate the role of low frequency AMOC variability on Arctic climate in a 1000 years control simulation of the GFDL CM2.1 coupled climate model. Simulated Arctic sea-ice extent anomaly is found to be highly anti-correlated with Arctic SAT anomaly, similar to observations. The coupled climate model also simulates the amplification of Arctic SAT anomalies by a factor of 4 of global SAT anomalies. A strong correlation is also found between the simulated AMO and Arctic SAT and sea-ice extent anomalies on decadal time-scales. The AMO is mainly induced by low frequency AMOC variations in the control simulation. Spatially, the AMO demonstrates the largest influence on the Bering, Labrador and Nordic Seas sea-ice concentration anomalies, similar to the observed spatial pattern of the Arctic sea-ice declining trend since 1979. Both observations and climate model simulations suggest a strong role of AMOC on decadal Arctic climate variability. Our model results suggest that the intensifying AMOC, in addition to anthropogenic greenhouse gases induced global warming, might have also contributed to the recent decline in Arctic sea-ice.

  12. Manganese cycles in Arctic marine sediments - Climate signals or diagenesis?

    NASA Astrophysics Data System (ADS)

    März, C.; Stratmann, A.; Eckert, S.; Schnetger, B.; Brumsack, H.-J.

    2009-04-01

    In comparison to sediments from other parts of the world ocean, the inorganic geochemistry of Arctic Ocean sediments is poorly investigated. However, marked light to dark brown layers are well-known features of Quaternary Arctic sediments, and have been related to variable Mn contents. Brown layers represent intervals relatively rich in Mn (often > 1 wt.%), while yellowish-greyish intervals contain less Mn. As these brown layers are widespread in pelagic Quaternary deposits of the Arctic Ocean, there are attempts to use them as stratigraphic, age-equivalent marker horizons that are genetically related to global climate changes (e.g. Jakobsson et al., 2000; Löwemark et al., 2008). In the Arctic Ocean, other conventional stratigraphic methods often fail, therefore the use of Mn-rich layers as a chemostratigraphic tool seems to be a promising approach. However, several inorganic-geochemical and modelling studies of Mn cycles in the Arctic as well as in other parts of the world ocean have shown that multiple Mn layers in marine sediments can be created by non-steady state diagenetic processes, i.e. secondary Mn redistribution in the sediment due to microbially mediated dissolution-reprecipitation reactions (e.g. Li et al., 1969; Gobeil et al., 1997; Burdige, 2006; Katsev et al., 2006). Such biogeochemical processes can lead to rapid migration or fixation of redox boundaries in the sediment, resulting in the formation or (partial) destruction of metal-rich layers several thousands of years after sediment deposition. As this clearly would alter primary paleoenvironmental signals recorded in the sediments, we see an urgent need to unravel the real stratigraphic potential of Arctic Mn cycles before they are readily established as standard tools. For this purpose, we are studying Mn cycles in Arctic Ocean sediments recovered during R/V Polarstern expedition ARK XXIII/3 on the Mendeleev Ridge (East Siberian Sea). First results of pore water and sediment composition

  13. Arctic marine mammals and climate change: impacts and resilience.

    PubMed

    Moore, Sue E; Huntington, Henry P

    2008-03-01

    Evolutionary selection has refined the life histories of seven species (three cetacean [narwhal, beluga, and bowhead whales], three pinniped [walrus, ringed, and bearded seals], and the polar bear) to spatial and temporal domains influenced by the seasonal extremes and variability of sea ice, temperature, and day length that define the Arctic. Recent changes in Arctic climate may challenge the adaptive capability of these species. Nine other species (five cetacean [fin, humpback, minke, gray, and killer whales] and four pinniped [harp, hooded, ribbon, and spotted seals]) seasonally occupy Arctic and subarctic habitats and may be poised to encroach into more northern latitudes and to remain there longer, thereby competing with extant Arctic species. A synthesis of the impacts of climate change on all these species hinges on sea ice, in its role as: (1) platform, (2) marine ecosystem foundation, and (3) barrier to non-ice-adapted marine mammals and human commercial activities. Therefore, impacts are categorized for: (1) ice-obligate species that rely on sea ice platforms, (2) ice-associated species that are adapted to sea ice-dominated ecosystems, and (3) seasonally migrant species for which sea ice can act as a barrier. An assessment of resilience is far more speculative, as any number of scenarios can be envisioned, most of them involving potential trophic cascades and anticipated human perturbations. Here we provide resilience scenarios for the three ice-related species categories relative to four regions defined by projections of sea ice reductions by 2050 and extant shelf oceanography. These resilience scenarios suggest that: (1) some populations of ice-obligate marine mammals will survive in two regions with sea ice refugia, while other stocks may adapt to ice-free coastal habitats, (2) ice-associated species may find suitable feeding opportunities within the two regions with sea ice refugia and, if capable of shifting among available prey, may benefit from

  14. New insights on Arctic Quaternary climate variability from palaeo-records and numerical modelling

    NASA Astrophysics Data System (ADS)

    Jakobsson, Martin; Long, Antony; Ingólfsson, Ólafur; Kjær, Kurt H.; Spielhagen, Robert F.

    2010-12-01

    Terrestrial and marine geological archives in the Arctic contain information on environmental change through Quaternary interglacial-glacial cycles. The Arctic Palaeoclimate and its Extremes (APEX) scientific network aims to better understand the magnitude and frequency of past Arctic climate variability, with focus on the "extreme" versus the "normal" conditions of the climate system. One important motivation for studying the amplitude of past natural environmental changes in the Arctic is to better understand the role of this region in a global perspective and provide base-line conditions against which to explore potential future changes in Arctic climate under scenarios of global warming. In this review we identify several areas that are distinct to the present programme and highlight some recent advances presented in this special issue concerning Arctic palaeo-records and natural variability, including spatial and temporal variability of the Greenland Ice Sheet, Arctic Ocean sediment stratigraphy, past ice shelves and marginal marine ice sheets, and the Cenozoic history of Arctic Ocean sea ice in general and Holocene oscillations in sea ice concentrations in particular. The combined sea ice data suggest that the seasonal Arctic sea ice cover was strongly reduced during most of the early Holocene and there appear to have been periods of ice free summers in the central Arctic Ocean. This has important consequences for our understanding of the recent trend of declining sea ice, and calls for further research on causal links between Arctic climate and sea ice.

  15. The role of snow cover affecting boreal-arctic soil freeze-thaw and carbon dynamics

    NASA Astrophysics Data System (ADS)

    Yi, Y.; Kimball, J. S.; Rawlins, M. A.; Moghaddam, M.; Euskirchen, E. S.

    2015-10-01

    Northern Hemisphere permafrost affected land areas contain about twice as much carbon as the global atmosphere. This vast carbon pool is vulnerable to accelerated losses through mobilization and decomposition under projected global warming. Satellite data records spanning the past 3 decades indicate widespread reductions (~ 0.8-1.3 days decade-1) in the mean annual snow cover extent and frozen-season duration across the pan-Arctic domain, coincident with regional climate warming trends. How the soil carbon pool responds to these changes will have a large impact on regional and global climate. Here, we developed a coupled terrestrial carbon and hydrology model framework with a detailed 1-D soil heat transfer representation to investigate the sensitivity of soil organic carbon stocks and soil decomposition to climate warming and changes in snow cover conditions in the pan-Arctic region over the past 3 decades (1982-2010). Our results indicate widespread soil active layer deepening across the pan-Arctic, with a mean decadal trend of 6.6 ± 12.0 (SD) cm, corresponding to widespread warming. Warming promotes vegetation growth and soil heterotrophic respiration particularly within surface soil layers (≤ 0.2 m). The model simulations also show that seasonal snow cover has a large impact on soil temperatures, whereby increases in snow cover promote deeper (≥ 0.5 m) soil layer warming and soil respiration, while inhibiting soil decomposition from surface (≤ 0.2 m) soil layers, especially in colder climate zones (mean annual T ≤ -10 °C). Our results demonstrate the important control of snow cover on northern soil freeze-thaw and soil carbon decomposition processes and the necessity of considering both warming and a change in precipitation and snow cover regimes in characterizing permafrost soil carbon dynamics.

  16. Evaluation of the Regional Arctic System Model (RASM) - Process-resolving Arctic Climate Simulation

    NASA Astrophysics Data System (ADS)

    Maslowski, Wieslaw

    2016-04-01

    The Regional Arctic System Model (RASM) has been developed to better understand the past and present operation of Arctic System at process scale and to predict its change at time scales from days to decades, in support of the US environmental assessment and prediction needs. RASM is a limited-area, fully coupled ice-ocean-atmosphere-land model that uses the Community Earth System Model (CESM) framework. It includes the Weather Research and Forecasting (WRF) model, the LANL Parallel Ocean Program (POP) and Community Ice Model (CICE) and the Variable Infiltration Capacity (VIC) land hydrology model. The ocean and sea ice models used in RASM are regionally configured versions of those used in CESM, while WRF replaces the Community Atmospheric Model (CAM). In addition, a streamflow routing (RVIC) model was recently implemented in RASM to transport the freshwater flux from the land surface to the Arctic Ocean. The model domain is configured at an eddy-permitting resolution of 1/12° (or ~9km) for the ice-ocean and 50 km for the atmosphere-land model components. It covers the entire Northern Hemisphere marine cryosphere, terrestrial drainage to the Arctic Ocean and its major inflow and outflow pathways, with optimal extension into the North Pacific / Atlantic to model the passage of cyclones into the Arctic. In addition, a 1/48° (or ~2.4km) grid for the ice-ocean model components has been recently configured. All RASM components are coupled at high frequency (currently at 20-minute intervals) to allow realistic representation of inertial interactions among the model components. In addition to an overview of RASM technical details, model results are presented from both fully coupled and subsets of RASM, where the atmospheric and land components are replaced with prescribed realistic atmospheric reanalysis data to evaluate model skill in representing seasonal climatology as well as interannual and multidecadal climate variability. Selected physical processes and resulting

  17. Changing climate increases biological productivity in the Arctic

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2011-11-01

    Climate change is leading to increased biological productivity in the coastal Arctic. As ice melts and recedes far from land, winds interact with open waters to increase the upwelling of nutrient-rich deep water and stimulate biological productivity. Tremblay et al. quantified these changes using remote sensing and in situ observations in the coastal Beaufort Sea. They found that ice ablation and the combination of increased upwelling and greater light penetration into the water column during fall 2007 and summer 2008 increased the production of ice algae, phytoplankton, and zooplankton by 2-6 times. (Geophysical Research Letters, doi:10.1029/2011GL048825, 2011)

  18. Arctic ecosystem structure and functioning shaped by climate and herbivore body size

    NASA Astrophysics Data System (ADS)

    Legagneux, P.; Gauthier, G.; Lecomte, N.; Schmidt, N. M.; Reid, D.; Cadieux, M.-C.; Berteaux, D.; Bêty, J.; Krebs, C. J.; Ims, R. A.; Yoccoz, N. G.; Morrison, R. I. G.; Leroux, S. J.; Loreau, M.; Gravel, D.

    2014-05-01

    Significant progress has been made in our understanding of species-level responses to climate change, but upscaling to entire ecosystems remains a challenge. This task is particularly urgent in the Arctic, where global warming is most pronounced. Here we report the results of an international collaboration on the direct and indirect effects of climate on the functioning of Arctic terrestrial ecosystems. Our data from seven terrestrial food webs spread along a wide range of latitudes (~1,500 km) and climates (Δ mean July temperature = 8.5 °C) across the circumpolar world show the effects of climate on tundra primary production, food-web structure and species interaction strength. The intensity of predation on lower trophic levels increased significantly with temperature, at approximately 4.5% per °C. Temperature also affected trophic interactions through an indirect effect on food-web structure (that is, diversity and number of interactions). Herbivore body size was a major determinant of predator-prey interactions, as interaction strength was positively related to the predator-prey size ratio, with large herbivores mostly escaping predation. There is potential for climate warming to cause a switch from bottom-up to top-down regulation of herbivores. These results are critical to resolving the debate on the regulation of tundra and other terrestrial ecosystems exposed to global change.

  19. Frequent sexual reproduction and high intraspecific variation in Salix arctica: Implications for a terrestrial feedback to climate change in the High Arctic

    NASA Astrophysics Data System (ADS)

    Steltzer, Heidi; Hufbauer, Ruth A.; Welker, Jeffery M.; Casalis, Maxime; Sullivan, Patrick F.; Chimner, Rodney

    2008-09-01

    Genetic variation at molecular loci may underlie important variation in the phenotypes of arctic plants. Such intraspecific variation may be a neglected but important component of biological diversity in the Arctic that could impact how arctic ecosystems respond to climate change. Here, we characterized genetic and phenotypic variation in Salix arctica and evaluated the effect of S. arctica on ecosystem CO2 exchange, a process by which terrestrial ecosystems in the Arctic feedback to the global climate system. We found high genetic variation at microsatellite loci of S. arctica collected from an inland and a coastal site in Greenland that indicates sexual reproduction has occurred frequently as the ice sheet has retreated. Across the North American range of S. arctica, ten chloroplast DNA haplotypes were identified. Haplotype diversity and allelic richness were high overall and similar across regions with different glacial histories. Phenotypic variation in ecologically important traits varied substantially in a High Arctic population of S. arctica. In a widespread High Arctic ecosystem, a net loss of CO2 to the atmosphere was observed except where S. arctica was present. We suggest that high genetic variation in S. arctica is in part a result of frequent sexual reproduction, and that the phenotypic variation we observed is likely to be at least partially genetic-based. This would enable a productive High Arctic species to adapt and potentially prosper as climate changes, and thus affect the terrestrial feedback of the Arctic to the climate system.

  20. Arctic Climate Change Analysed By Two 30-year Scenario Regional Climate Model Runs

    NASA Astrophysics Data System (ADS)

    Kiilsholm, S.; Christensen, J. H.

    High-resolution climate change simulations for an area covering the entire Arctic have been conducted with the regional climate model (RCM) HIRHAM. The emission sce- narios used were the IPCC SRES1 marker scenarios A2 and B2. Three 30-year time slice experiments were conducted with HIRHAM for periods representing present-day (1961-1990) and the future (2071-2100) in the two scenarios. Changes of the climate between these two periods will be presented with special emphasize on the climate of Greenland.

  1. Climate change alters the structure of arctic marine food webs due to poleward shifts of boreal generalists

    PubMed Central

    Kortsch, Susanne; Primicerio, Raul; Fossheim, Maria; Dolgov, Andrey V.; Aschan, Michaela

    2015-01-01

    Climate-driven poleward shifts, leading to changes in species composition and relative abundances, have been recently documented in the Arctic. Among the fastest moving species are boreal generalist fish which are expected to affect arctic marine food web structure and ecosystem functioning substantially. Here, we address structural changes at the food web level induced by poleward shifts via topological network analysis of highly resolved boreal and arctic food webs of the Barents Sea. We detected considerable differences in structural properties and link configuration between the boreal and the arctic food webs, the latter being more modular and less connected. We found that a main characteristic of the boreal fish moving poleward into the arctic region of the Barents Sea is high generalism, a property that increases connectance and reduces modularity in the arctic marine food web. Our results reveal that habitats form natural boundaries for food web modules, and that generalists play an important functional role in coupling pelagic and benthic modules. We posit that these habitat couplers have the potential to promote the transfer of energy and matter between habitats, but also the spread of pertubations, thereby changing arctic marine food web structure considerably with implications for ecosystem dynamics and functioning. PMID:26336179

  2. Climate change alters the structure of arctic marine food webs due to poleward shifts of boreal generalists.

    PubMed

    Kortsch, Susanne; Primicerio, Raul; Fossheim, Maria; Dolgov, Andrey V; Aschan, Michaela

    2015-09-01

    Climate-driven poleward shifts, leading to changes in species composition and relative abundances, have been recently documented in the Arctic. Among the fastest moving species are boreal generalist fish which are expected to affect arctic marine food web structure and ecosystem functioning substantially. Here, we address structural changes at the food web level induced by poleward shifts via topological network analysis of highly resolved boreal and arctic food webs of the Barents Sea. We detected considerable differences in structural properties and link configuration between the boreal and the arctic food webs, the latter being more modular and less connected. We found that a main characteristic of the boreal fish moving poleward into the arctic region of the Barents Sea is high generalism, a property that increases connectance and reduces modularity in the arctic marine food web. Our results reveal that habitats form natural boundaries for food web modules, and that generalists play an important functional role in coupling pelagic and benthic modules. We posit that these habitat couplers have the potential to promote the transfer of energy and matter between habitats, but also the spread of pertubations, thereby changing arctic marine food web structure considerably with implications for ecosystem dynamics and functioning. PMID:26336179

  3. Climate change on arctic environment, ecosystem services and society (CLICHE)

    NASA Astrophysics Data System (ADS)

    Weckström, J.; Korhola, A.; Väliranta, M.; Seppä, H.; Luoto, M.; Tuittila, E.-S.; Leppäranta, M.; Kahilainen, K.; Saarinen, J.; Heikkinen, H.

    2012-04-01

    The predicted climate warming has raised many questions and concerns about its impacts on the environment and society. As a respond to the need of holistic studies comprising both of these areas, The Academy of Finland launched The Finnish Research Programme on Climate Change (FICCA 2011-2014) in spring 2010 with the main aim to focus on the interaction between the environment and society. Ultimately 11 national consortium projects were funded (total budget 12 million EUR). Here we shortly present the main objectives of the largest consortium project "Climate change on arctic environment, ecosystem services and society" (CLICHE). The CLICHE consortium comprises eight interrelated work packages (treeline, diversity, peatlands, snow, lakes, fish, tourism, and traditional livelihoods), each led by a prominent research group and a team leader. The research consortium has three main overall objectives: 1) Investigate, map and model the past, present and future climate change-induced changes in central ecosystems of the European Arctic with unprecedented precision 2) Deepen our understanding of the basic principles of ecosystem and social resilience and dynamics; identify key taxa, structures or processes that clearly indicate impending or realised global change through their loss, occurrence or behaviour, using analogues from the past (e.g. Holocene Thermal Maximum, Medieval Warm Period), experiments, observations and models 3) Develop adaptation and mitigation strategies to minimize the adverse effects of climate change on local communities, traditional livelihoods, fisheries, and tourism industry, and promote sustainable development of local community structures and enhance the quality of life of local human populations. As the project has started only recently no final results are available yet. However, the fieldwork as well as the co-operation between the research teams has thus far been very successful. Thus, the expectations for the final outcome of the project

  4. Shrub expansion and climate feedbacks in Arctic tundra

    NASA Astrophysics Data System (ADS)

    Loranty, Michael M.; Goetz, Scott J.

    2012-03-01

    Arctic tundra ecosystems stand to play a substantial role in both the magnitude and rate of global climate warming over the coming decades and centuries. The exact nature of this role will be determined by the combined effects of currently amplified rates of climate warming in the Arctic (Serreze et al 2000) and a series of related positive climate feedbacks that include mobilization of permafrost carbon (Schuur et al 2008), decreases in surface albedo (Chapin et al 2005) and evapotranspiration (ET) mediated increases in atmospheric water vapor (Swann et al 2010). Conceptually, these feedback mechanisms are intuitive and readily comprehensible: warming-induced permafrost thaw will make new soil carbon pools accessible for microbial respiration, and increased vegetation productivity, expansion of shrubs in particular, will lower surface reflectance and increase ET. However, our current understanding of these feedback mechanisms relies largely on limited and local field studies and, as such, the quantitative estimates of feedback effects on regional and global climate require spatial upscaling and uncertainty estimates derived from models. Moreover, the feedback mechanisms interact and their combined net effect on climate is highly variable and not well characterized. A recent study by Bonfils et al (2012) is among the first to explicitly examine how shrub expansion in tundra ecosystems will impact regional climate. Using an Earth system model, Bonfils et al find that an idealized 20% increase in shrub cover north of 60°N latitude will lead to annual temperature increases of 0.66 °C and 1.84 °C, respectively, when the shrubs are 0.5 m and 2 m tall. The modeled temperature increases arise from atmospheric heating as a combined consequence of decreased albedo and increased ET. The primary difference between the two cases is associated with the fact that tall shrubs protrude above the snow, thus reducing albedo year round, whereas short shrubs are completely

  5. Climate Change Experiments in Arctic Ecosystems: Scientific Strategy and Design Criteria

    NASA Astrophysics Data System (ADS)

    Wullschleger, S. D.; Hinzman, L. D.; McGuire, A. D.; Oberbauer, S. F.; Oechel, W. C.; Norby, R. J.; Thornton, P. E.; Schuur, E. A.; Shugart, H. H.; Walsh, J. E.; Wilson, C. J.

    2010-12-01

    Arctic and subarctic ecosystems are sensitive to changes in climate. These are among the largest and coldest of all ecosystems and are perceived by many as especially vulnerable to environmental change. Warming, in particular, is expected to be greatest in northern latitudes with potentially significant consequences for tundra, taiga, and peat lands. Observational evidence suggests that warming is already affecting physical and ecological processes in high-latitude ecosystems. Models predict that permafrost degradation and the northward expansion of shrubs into tundra represent important feedbacks on climate. Manipulative experiments can help understand the vulnerability of ecosystems to climate warming. Previous attempts to manipulate the environment of ecosystems in arctic and subarctic regions have focused on warming plant and soils, but treatments have been limited to small scales and modest increases in temperature. Manipulating the environment at larger scales and exposing ecosystems to higher temperatures for longer periods of time will be required to fully describe the physical, chemical, and biological mechanisms that govern land-atmosphere interactions. A variety of logistical and engineering challenges must be overcome and new approaches developed before we can address the questions being asked of the scientific community especially as we continue to move toward large-scale and long-term experiments. In light of the many uncertainties that surround the response of high-latitude ecosystems to global climate change, it is important that the scientific community consider how manipulative experiments can address and resolve ecosystem impacts and feedbacks to climate. A workshop sponsored by the Department of Energy, Office of Science was recently held at the University of Alaska, Fairbanks. The goal of the workshop was to highlight conclusions from observational and modeling studies about the response of arctic and subarctic ecosystems to a changing climate

  6. Climatic and biotic extreme events moderate long-term responses of above- and belowground sub-Arctic heathland communities to climate change.

    PubMed

    Bokhorst, Stef; Phoenix, Gareth K; Berg, Matty P; Callaghan, Terry V; Kirby-Lambert, Christopher; Bjerke, Jarle W

    2015-11-01

    Climate change impacts are not uniform across the Arctic region because interacting factors causes large variations in local ecosystem change. Extreme climatic events and population cycles of herbivores occur simultaneously against a background of gradual climate warming trends and can redirect ecosystem change along routes that are difficult to predict. Here, we present the results from sub-Arctic heath vegetation and its belowground micro-arthropod community in response to the two main drivers of vegetation damage in this region: extreme winter warming events and subsequent outbreaks of the defoliating autumnal moth caterpillar (Epirrita autumnata). Evergreen dwarf shrub biomass decreased (30%) following extreme winter warming events and again by moth caterpillar grazing. Deciduous shrubs that were previously exposed to an extreme winter warming event were not affected by the moth caterpillar grazing, while those that were not exposed to warming events (control plots) showed reduced (23%) biomass from grazing. Cryptogam cover increased irrespective of grazing or winter warming events. Micro-arthropods declined (46%) following winter warming but did not respond to changes in plant community. Extreme winter warming and caterpillar grazing suppressed the CO2 fluxes of the ecosystem. Evergreen dwarf shrubs are disadvantaged in a future sub-Arctic with more stochastic climatic and biotic events. Given that summer warming may further benefit deciduous over evergreen shrubs, event and trend climate change may both act against evergreen shrubs and the ecosystem functions they provide. This is of particular concern given that Arctic heath vegetation is typically dominated by evergreen shrubs. Other components of the vegetation showed variable responses to abiotic and biotic events, and their interaction indicates that sub-Arctic vegetation response to multiple pressures is not easy to predict from single-factor responses. Therefore, while biotic and climatic events may

  7. Influence of Sea Ice on Arctic Marine Sulfur Biogeochemistry in the Community Climate System Model

    SciTech Connect

    Deal, Clara; Jin, Meibing

    2013-06-30

    Global climate models (GCMs) have not effectively considered how responses of arctic marine ecosystems to a warming climate will influence the global climate system. A key response of arctic marine ecosystems that may substantially influence energy exchange in the Arctic is a change in dimethylsulfide (DMS) emissions, because DMS emissions influence cloud albedo. This response is closely tied to sea ice through its impacts on marine ecosystem carbon and sulfur cycling, and the ice-albedo feedback implicated in accelerated arctic warming. To reduce the uncertainty in predictions from coupled climate simulations, important model components of the climate system, such as feedbacks between arctic marine biogeochemistry and climate, need to be reasonably and realistically modeled. This research first involved model development to improve the representation of marine sulfur biogeochemistry simulations to understand/diagnose the control of sea-ice-related processes on the variability of DMS dynamics. This study will help build GCM predictions that quantify the relative current and possible future influences of arctic marine ecosystems on the global climate system. Our overall research objective was to improve arctic marine biogeochemistry in the Community Climate System Model (CCSM, now CESM). Working closely with the Climate Ocean Sea Ice Model (COSIM) team at Los Alamos National Laboratory (LANL), we added 1 sea-ice algae and arctic DMS production and related biogeochemistry to the global Parallel Ocean Program model (POP) coupled to the LANL sea ice model (CICE). Both CICE and POP are core components of CESM. Our specific research objectives were: 1) Develop a state-of-the-art ice-ocean DMS model for application in climate models, using observations to constrain the most crucial parameters; 2) Improve the global marine sulfur model used in CESM by including DMS biogeochemistry in the Arctic; and 3) Assess how sea ice influences DMS dynamics in the arctic marine

  8. Climate change and natural hazards in the Arctic

    NASA Astrophysics Data System (ADS)

    Eichelberger, J. C.; Eichelberger, L. P.

    2015-12-01

    Climate change is motivating much of the science research in the Arctic. Natural hazards, which have always been with us and can be influenced by climate, also pose a serious threat to sustainability of Arctic communities, the Native cultures they support, and the health and wellbeing of their residents. These are themes of the US Chairship of the Arctic Council. For example, repetitive floods, often associated with spring ice jams, are a particularly severe problem for river communities. People live near rivers because access to food, water and river transportation support an indigenous subsistence lifestyle. Some settlement sites for Indigenous Peoples were mandated by distant authorities without regard to natural hazards, in Alaska no less than in other countries. Thus bad policy of the past casts a long shadow into the future. Remote communities are subject to multiple challenges, including natural hazards, access to education, and limited job opportunities. These intersect to reproduce structural vulnerability and have over time created a need for substantial support from government. In the past 40 years, the themes of "sustainability" and "self reliance" have become prominent strategies for governance at both state and local levels. Communities now struggle to demonstrate their sustainability while grappling with natural hazards and chronic poverty. In the extreme, the shifting of responsibility to resource-poor communities can be called "structural violence". Accepting the status quo can mean living without sanitation and reliable water supply, leading to the high observed rates of disease not normally encountered in developed countries. Many of the efforts to address climate change and natural hazards are complementary: monitoring the environment; forecasting extreme events; and community-based participatory research and planning. Natural disaster response is complementary to the Arctic Council's Search and Rescue (SAR) initiative, differing in that those

  9. Will the Arctic Land Surface become Wetter or Drier in Response to a Warming Climate

    NASA Astrophysics Data System (ADS)

    Hinzman, L. D.; Rawlins, M.; Serreze, M.; Vorosmarty, C. J.; Walsh, J. E.

    2015-12-01

    There is much concern about a potentially "accelerated" hydrologic cycle, with associated extremes in weather and climate-related phenomena. Whether this translates into wetter or drier conditions across arctic landscapes remains an open question. Arctic ecosystems differ substantially from those in temperate regions, largely due to the interactions of extremes in climate and land surface characteristics. Ice-rich permafrost prevents percolation of rainfall or snowmelt water, often maintaining a moist to saturated active layer where the permafrost table is shallow. Permafrost may also block the lateral movement of groundwater, and act as a confining unit for water in sub- or intra-permafrost aquifers. However, as permafrost degrades, profound changes in interactions between groundwater and surface water occur that affect the partitioning among the water balance components with subsequent impacts to the surface energy balance and essential ecosystem processes. Most simulations of arctic climate project sustained increases in temperature and gradual increases in precipitation over the 21st century. However, most climatic models do not correctly represent the essential controls that permafrost exerts on hydrological, ecological, and climatological processes. If warming continues as projected, we expect large-scale changes in surface hydrology as permafrost degrades. Where groundwater gradients are downward (i.e. surface water will infiltrate to subsurface groundwater), as in most cases, we may expect improved drainage and drier soils, which would result in reduced evaporation and transpiration (ET). In some special cases, where the groundwater gradient is upward (as in many wetlands or springs) surface soils may become wetter or inundated as permafrost degrades. Further, since soil moisture is a primary factor controlling ecosystem processes, interactions between ecosystems, GHG emissions, and high-latitude climate must also be considered highly uncertain. These inter

  10. Changing climate: Geothermal evidence from permafrost in the Alaskan Arctic

    USGS Publications Warehouse

    Lachenbruch, A.H.; Marshall, B.V.

    1986-01-01

    Temperature profiles measured in permafrost in northernmost Alaska usually have anomalous curvature in the upper 100 meters or so. When analyzed by heat-conduction theory, the profiles indicate a variable but widespread secular warming of the permafrost surface, generally in the range of 2 to 4 Celsius degrees during the last few decades to a century. Although details of the climatic change cannot be resolved with existing data, there is little doubt of its general magnitude and timing; alternative explanations are limited by the fact that heat transfer in cold permafrost is exclusively by conduction. Since models of greenhouse warming predict climatic change will be greatest in the Arctic and might already be in progress, it is prudent to attempt to understand the rapidly changing thermal regime in this region.

  11. Identifying climate change threats to the arctic archaeological record

    NASA Astrophysics Data System (ADS)

    Murray, Maribeth; Jensen, Anne; Friesen, Max

    2011-05-01

    Global Climate Change and the Polar Archaeological Record; Tromsø, Norway, 15-16 February 2011 ; A workshop was held at the Institute of Archaeology and Social Anthropology, University of Tromsø, in Norway, to catalyze growing concern among polar archaeologists about global climate change and attendant threats to the polar archaeological and paleoecological records. Arctic archaeological sites contain an irreplaceable record of the histories of the many societies that have lived in the region over past millennia. Associated paleoecological deposits provide powerful proxy evidence for paleoclimate and ecosystem structure and function and direct evidence of species diversity, distributions, and genetic variability. Archaeological records can span most of the Holocene (the past ∼12,000 years), depending upon location, and paleoecological records extend even further. Most are largely unstudied, and, although extremely vulnerable to destruction, they are poorly monitored and not well protected. Yet these records are key to understanding how the Arctic has functioned as a system, how humans were integrated into it, and how humans may have shaped it. Such records provide a wide range of data that are not obtainable from sources such as ice and ocean cores; these data are needed for understanding the past, assessing current and projecting future conditions, and adapting to ongoing change.

  12. Status of Wind-Diesel Applications in Arctic Climates: Preprint

    SciTech Connect

    Baring-Gould, I.; Corbus, D.

    2007-12-01

    The rising cost of diesel fuel and the environmental regulation for its transportation, use, and storage, combined with the clear impacts of increased arctic temperatures, is driving remote communities to examine alternative methods of providing power. Over the past few years, wind energy has been increasingly used to reduce diesel fuel consumption, providing economic, environmental, and security benefits to the energy supply of communities from Alaska to Antarctica. This summary paper describes the current state of wind-diesel systems, reviews the operation of wind-diesel plants in cold climates, discusses current research activities pertaining to these systems, and addresses their technical and commercial challenges. System architectures, dispatch strategies, and operating experience from a variety of wind-diesel systems in Alaska will be reviewed. Specific focus will also be given to the control of power systems with large amounts of wind generation and the complexities of replacing diesel engine waste heat with excess wind energy, a key factor in assessing power plants for retrofit. A brief overview of steps for assessing the viability of retrofitting diesel power systems with wind technologies will also be provided. Because of the large number of isolated diesel minigrids, the market for adding wind to these systems is substantial, specifically in arctic climates and on islands that rely on diesel-only power generation.

  13. Arctic Climate during Eocene Hyperthermals: Wet Summers on Ellesmere Island?

    NASA Astrophysics Data System (ADS)

    Greenwood, D. R.; West, C. K.; Basinger, J. F.

    2012-12-01

    Previous work has shown that during the late Paleocene to middle Eocene, mesothermal conditions (i.e., MAT ~12-15° C) and high precipitation (MAP > 150cm/yr) characterized Arctic climates - an Arctic rain forest. Recent analyses of Arctic Eocene wood stable isotope chemistry are consistent with the annual and seasonal temperature estimates from leaf physiognomy and nearest living relative analogy from fossil plants, including the lack of freezing winters, but is interpreted as showing that there was a summer peak in precipitation - modern analogs are best sought on the summer-wet east coasts (e.g., China, Japan, South Korea) not the winter-wet west coasts of present-day northern temperate continents (e.g., Pacific northwest of North America). Highly seasonal 'monsoon-type' summer-wet precipitation regimes (i.e., summer precip./winter precip. > 3.0) seem to characterize Eocene hyperthermal conditions in several regions of the earth, including the Arctic and Antarctic, based on both climate model sensitivity experiments and the paleoclimate proxy evidence. The leaf physiognomy proxy previously applied to estimate Arctic Paleogene precipitation was leaf area analysis (LAA), a correlation between mean leaf size in woody dicot vegetation and annual precipitation. New data from modern monsoonal sites, however demonstrates that for deciduous-dicot dominated vegetation, summer precipitation determines mean leaf size, not annual totals, and therefore that under markedly seasonal precipitation and/or light regimes that summer precipitation is being estimated using LAA. Presented here is a new analysis of a leaf macrofloras from 3 separate florules of the Margaret Formation (Split Lake, Stenkul Fiord and Strathcona Fiord) from Ellesmere Island that are placed stratigraphically as early Eocene, and likely fall within Eocene thermal maximum 1 (ETM1; = the 'PETM') or ETM2. These floras are each characterized by a mix of large-leafed and small-leafed dicot taxa, with overall

  14. Relating Regional Arctic Sea Ice and climate extremes over Europe

    NASA Astrophysics Data System (ADS)

    Ionita-Scholz, Monica; Grosfeld, Klaus; Lohmann, Gerrit; Scholz, Patrick

    2016-04-01

    The potential increase of temperature extremes under climate change is a major threat to society, as temperature extremes have a deep impact on environment, hydrology, agriculture, society and economy. Hence, the analysis of the mechanisms underlying their occurrence, including their relationships with the large-scale atmospheric circulation and sea ice concentration, is of major importance. At the same time, the decline in Arctic sea ice cover during the last 30 years has been widely documented and it is clear that this change is having profound impacts at regional as well as planetary scale. As such, this study aims to investigate the relation between the autumn regional sea ice concentration variability and cold winters in Europe, as identified by the numbers of cold nights (TN10p), cold days (TX10p), ice days (ID) and consecutive frost days (CFD). We analyze the relationship between Arctic sea ice variation in autumn (September-October-November) averaged over eight different Arctic regions (Barents/Kara Seas, Beaufort Sea, Chukchi/Bering Seas, Central Arctic, Greenland Sea, Labrador Sea/Baffin Bay, Laptev/East Siberian Seas and Northern Hemisphere) and variations in atmospheric circulation and climate extreme indices in the following winter season over Europe using composite map analysis. Based on the composite map analysis it is shown that the response of the winter extreme temperatures over Europe is highly correlated/connected to changes in Arctic sea ice variability. However, this signal is not symmetrical for the case of high and low sea ice years. Moreover, the response of temperatures extreme over Europe to sea ice variability over the different Arctic regions differs substantially. The regions which have the strongest impact on the extreme winter temperature over Europe are: Barents/Kara Seas, Beaufort Sea, Central Arctic and the Northern Hemisphere. For the years of high sea ice concentration in the Barents/Kara Seas there is a reduction in the number

  15. Modeling the Response of Arctic Vegetation to Increasing Atmospheric Carbon Dioxide and Climate Change

    NASA Astrophysics Data System (ADS)

    Cassidy, E. S.; Snyder, P. K.

    2009-12-01

    An increase in atmospheric carbon dioxide is contributing to planetary warming that is strongest over high latitude land areas of the Northern Hemisphere. Elevated levels of atmospheric carbon dioxide and strong warming have led to changes in vegetation distribution, permafrost depth, and snow cover, which significantly affect the interactions between the terrestrial ecosystem and the climate through biophysical and biogeochemical processes. With a continued rise in greenhouse gas emissions and additional warming in the high latitudes, uncertainty exists as to how the Arctic biosphere will respond in the coming decades and whether Arctic ecosystems will remain a carbon sink or instead become a source of carbon to the atmosphere. Elevated carbon dioxide and climate change can affect vegetation growth through changing the assimilation of carbon dioxide and the respiration of carbon from the vegetation and soil. Using a dynamic global vegetation model, the Integrated BIosphere Simulator Model (IBIS), potential changes in both the biophysical and biogeochemical processes of Arctic vegetation were analyzed to determine how future climate change and elevated atmospheric carbon dioxide may alter their functioning and ability to store carbon. High latitude regions were modeled using a variety of temperature, precipitation, and carbon dioxide scenarios. Changes in gross and net primary production, net ecosystem exchange, soil carbon, soil respiration, leaf area index, and biomass content were analyzed. Under high levels of carbon dioxide, net primary production increased at a greater rate than high levels of warming. Soil carbon decreased dramatically with high levels of warming as soil respiration increased, but soil carbon increased with higher levels of atmospheric carbon dioxide as the vegetation fixed more carbon. Net primary production also increased in scenarios with elevated precipitation. The results from the combined scenarios of climate and atmospheric carbon

  16. Influence of global climatic processes on environment The Arctic seas

    NASA Astrophysics Data System (ADS)

    Kholmyansky, Mikhael; Anokhin, Vladimir; Kartashov, Alexandr

    2016-04-01

    One of the most actual problems of the present is changes of environment of Arctic regions under the influence of global climatic processes. Authors as a result of the works executed by them in different areas of the Russian Arctic regions, have received the materials characterising intensity of these processes. Complex researches are carried out on water area and in a coastal zone the White, the Barents, the Kara and the East-Siberian seas, on lake water areas of subarctic region since 1972 on the present. Into structure of researches enter: hydrophysical, cryological observations, direct measurements of temperatures, the analysis of the drill data, electrometric definitions of the parametres of a frozen zone, lithodynamic and geochemical definitions, geophysical investigations of boreholes, studying of glaciers on the basis of visual observations and the analysis of photographs. The obtained data allows to estimate change of temperature of a water layer, deposits and benthonic horizon of atmosphere for last 25 years. On the average they make 0,38⁰C for sea waters, 0,23⁰C for friable deposits and 0,72⁰C for atmosphere. Under the influence of temperature changes in hydrosphere and lithosphere of a shelf cryolithic zone changes the characteristics. It is possible to note depth increase of roof position of the cryolithic zone on the most part of the studied water area. Modern fast rise in temperature high-ice rocks composing coast, has led to avalanche process thermo - denudation and to receipt in the sea of quantity of a material of 1978 three times exceeding level Rise in temperature involves appreciable deviation borders of the Arctic glacial covers. On our monitoring measurements change of the maintenance of oxygen in benthonic area towards increase that is connected with reduction of the general salinity of waters at the expense of fresh water arriving at ice thawing is noticed. It, in turn, leads to change of a biogene part of ecosystem. The executed

  17. Climate drift of AMOC, North Atlantic salinity and arctic sea ice in CFSv2 decadal predictions

    NASA Astrophysics Data System (ADS)

    Huang, Bohua; Zhu, Jieshun; Marx, Lawrence; Wu, Xingren; Kumar, Arun; Hu, Zeng-Zhen; Balmaseda, Magdalena A.; Zhang, Shaoqing; Lu, Jian; Schneider, Edwin K.; Kinter, James L., III

    2015-01-01

    There are potential advantages to extending operational seasonal forecast models to predict decadal variability but major efforts are required to assess the model fidelity for this task. In this study, we examine the North Atlantic climate simulated by the NCEP Climate Forecast System, version 2 (CFSv2), using a set of ensemble decadal hindcasts and several 30-year simulations initialized from realistic ocean-atmosphere states. It is found that a substantial climate drift occurs in the first few years of the CFSv2 hindcasts, which represents a major systematic bias and may seriously affect the model's fidelity for decadal prediction. In particular, it is noted that a major reduction of the upper ocean salinity in the northern North Atlantic weakens the Atlantic meridional overturning circulation (AMOC) significantly. This freshening is likely caused by the excessive freshwater transport from the Arctic Ocean and weakened subtropical water transport by the North Atlantic Current. A potential source of the excessive freshwater is the quick melting of sea ice, which also causes unrealistically thin ice cover in the Arctic Ocean. Our sensitivity experiments with adjusted sea ice albedo parameters produce a sustainable ice cover with realistic thickness distribution. It also leads to a moderate increase of the AMOC strength. This study suggests that a realistic freshwater balance, including a proper sea ice feedback, is crucial for simulating the North Atlantic climate and its variability.

  18. Arctic climate change in 21st century CMIP5 simulations with EC-Earth

    NASA Astrophysics Data System (ADS)

    Koenigk, Torben; Brodeau, Laurent; Graversen, Rune Grand; Karlsson, Johannes; Svensson, Gunilla; Tjernström, Michael; Willén, Ulrika; Wyser, Klaus

    2013-06-01

    The Arctic climate change is analyzed in an ensemble of future projection simulations performed with the global coupled climate model EC-Earth2.3. EC-Earth simulates the twentieth century Arctic climate relatively well but the Arctic is about 2 K too cold and the sea ice thickness and extent are overestimated. In the twenty-first century, the results show a continuation and strengthening of the Arctic trends observed over the recent decades, which leads to a dramatically changed Arctic climate, especially in the high emission scenario RCP8.5. The annually averaged Arctic mean near-surface temperature increases by 12 K in RCP8.5, with largest warming in the Barents Sea region. The warming is most pronounced in winter and autumn and in the lower atmosphere. The Arctic winter temperature inversion is reduced in all scenarios and disappears in RCP8.5. The Arctic becomes ice free in September in all RCP8.5 simulations after a rapid reduction event without recovery around year 2060. Taking into account the overestimation of ice in the twentieth century, our model results indicate a likely ice-free Arctic in September around 2040. Sea ice reductions are most pronounced in the Barents Sea in all RCPs, which lead to the most dramatic changes in this region. Here, surface heat fluxes are strongly enhanced and the cloudiness is substantially decreased. The meridional heat flux into the Arctic is reduced in the atmosphere but increases in the ocean. This oceanic increase is dominated by an enhanced heat flux into the Barents Sea, which strongly contributes to the large sea ice reduction and surface-air warming in this region. Increased precipitation and river runoff lead to more freshwater input into the Arctic Ocean. However, most of the additional freshwater is stored in the Arctic Ocean while the total Arctic freshwater export only slightly increases.

  19. Arctic Council Nations Could Encourage Development of Climate Indicator: Flux to the Atmosphere from Arctic Permafrost Carbon

    NASA Astrophysics Data System (ADS)

    Ekwurzel, B.; Yona, L.; Natali, S.; Holmes, R. M.; Schuur, E.

    2015-12-01

    Permafrost regions store almost twice the carbon in the atmosphere (Tarnocai et al 2009). As climate warms a proportion of this carbon will be released as carbon dioxide and methane. The Arctic Council may be best suited to harness international scientific collaboration for policy relevant knowledge about the global impacts of permafrost thaw. Scientists in Arctic Council and observer states have historically collaborated on permafrost research (e.g. Permafrost Carbon Network, part of Study of Environmental Arctic Change (SEARCH) project). This work increased knowledge of permafrost carbon pool size and vulnerability. However, data gaps persist across the Arctic. Despite gaps, numerous studies directly inform international policy negotiations aiming to stay below 2° C. Some suggest "permafrost carbon feedback" may comprise 3 to 11% of total allowed emissions through 2100 under a RCP4.5 (Schaefer et al2014). Understanding and accounting for future permafrost atmospheric carbon release requires science and policy coordination that the Arctic Council could incentivize. For example, Council nations could convene scientists and stakeholders to develop a Permafrost-Climate Indicator providing more direct decision support than current permafrost indicators, and identify research needed for a periodic estimate of Arctic permafrost CO2 and CH4 emissions. This presentation covers current challenges scientists and policymakers may face to develop a practical and robust Permafrost Climate Indicator. For example, which timescales are most appropriate for international emissions commitments? Do policy-relevant timescales align with current scientific knowledge? What are the uncertainties and how can they be decreased? We present likely strengths and challenges of a Permafrost Climate Indicator co-developed by scientists and stakeholders. Potential greenhouse gas atmospheric flux from Arctic permafrost carbon may be greater than some nations' United Nations emissions reductions

  20. Holocene Climate Change in Arctic Canada and Greenland

    NASA Astrophysics Data System (ADS)

    Briner, J. P.; McKay, N.; Axford, Y.; Bennike, O.; Bradley, R. S.; de Vernal, A.; Fisher, D. A.; Francus, P.; Fréchette, B.; Gajewski, K. J.; Jennings, A. E.; Kaufman, D. S.; Miller, G. H.; Rouston, C.; Wagner, B.

    2015-12-01

    We summarize the spatial and temporal pattern of climate change through the Holocene in Arctic Canada and Greenland. Our synthesis includes 47 records from a recent database of highly resolved, quantitative Holocene climate records from the Arctic (Sundqvist et al., 2014). We plot the temperature histories represented by the records in the database and compare them with paleoclimate information based on 53 additional records. Combined, the records include a variety of climate proxy types that range from ice (ice cores), land (lake and peat sequences) and marine (ocean sediment cores and coastal sediments) environments. The temperature-sensitive records indicate more consistent and earlier Holocene warmth in the north and east, and a more diffuse and later Holocene thermal maximum in the south and west. Principal components analysis reveals two dominant Holocene trends, one with early Holocene warmth followed by cooling in the middle Holocene, the other with a broader period of warmth in the middle Holocene followed by cooling in the late Holocene. The temperature decrease from the warmest to the coolest portions of the Holocene is 3.0±1.0°C on average (n=11 records). The Greenland Ice Sheet retracted to its minimum extent between 5 and 3 ka, consistent with many sites from around Greenland depicting a switch from warm to cool conditions around that time. The spatial pattern of temperature change through the Holocene was likely driven by the decrease in northern latitude summer insolation through the Holocene, the varied influence of waning ice sheets in the early Holocene, and the variable influx of Atlantic Water into the study region.

  1. Relevance of hydro-climatic change projection and monitoring for assessment of water cycle changes in the Arctic.

    PubMed

    Bring, Arvid; Destouni, Georgia

    2011-06-01

    Rapid changes to the Arctic hydrological cycle challenge both our process understanding and our ability to find appropriate adaptation strategies. We have investigated the relevance and accuracy development of climate change projections for assessment of water cycle changes in major Arctic drainage basins. Results show relatively good agreement of climate model projections with observed temperature changes, but high model inaccuracy relative to available observation data for precipitation changes. Direct observations further show systematically larger (smaller) runoff than precipitation increases (decreases). This result is partly attributable to uncertainties and systematic bias in precipitation observations, but still indicates that some of the observed increase in Arctic river runoff is due to water storage changes, for example melting permafrost and/or groundwater storage changes, within the drainage basins. Such causes of runoff change affect sea level, in addition to ocean salinity, and inland water resources, ecosystems, and infrastructure. Process-based hydrological modeling and observations, which can resolve changes in evapotranspiration, and groundwater and permafrost storage at and below river basin scales, are needed in order to accurately interpret and translate climate-driven precipitation changes to changes in freshwater cycling and runoff. In contrast to this need, our results show that the density of Arctic runoff monitoring has become increasingly biased and less relevant by decreasing most and being lowest in river basins with the largest expected climatic changes. PMID:21809779

  2. Modeling dynamics of circum-arctic tundra plant communities in response to climate warming and grazing pressure

    NASA Astrophysics Data System (ADS)

    Yu, Q.; Epstein, H. E.; Walker, D. A.; Forbes, B. C.; Vors, L. S.

    2011-12-01

    The Arctic is a complex system with strong interconnectedness among system components. Understanding the responses of the arctic tundra biome to a changing climate requires knowledge of the complex interactions among climate, soils, and the biological system. In this study, we investigate the individual and interactive effects of projected climate change and reindeer/caribou grazing across a variety of climate zones and soil nutrient levels on tundra plant community dynamics using an arctic vegetation model - ArcVeg. Our research questions include: 1) How does soil nutrient availability affect tundra vegetation responses to projected climate warming? 2) How does grazing affect tundra vegetation responses? 3) How do interactions of soil nutrients, climate warming and grazing affect tundra vegetation? We based our simulations on A1B scenario temperature data from the Intergovernmental Panel on Climate Change (IPCC), soil organic nitrogen data from Terrestrial Ecosystem Model (TEM) simulations and grazing pressure derived from reindeer/caribou population data from the CircumArctic Rangifer Monitoring and Assessment Network (CARMA). We found that in general tundra communities responded to warming with increased plant biomass, but the magnitude of the response is affected by the bioclimate zones, warming magnitude, available soil nutrients and grazing pressures. Regions with greater soil organic nitrogen responded to warming with greater biomass increase, Low Arctic tundra tended to have greater biomass increase than High Arctic tundra due to greater shrub abundance. However, such responses are mitigated by grazing. Regions with greater reindeer population and thus greater grazing intensity tended to have stronger negative effects on plant responses to warming than regions with less grazing. For example, in Subzone D, total biomass and NPP increases due to warming were about 71% and 43% in an Alaskan low grazing-intensity region, but 63% and 36% in a northwestern Canada

  3. Decadal variability of the Arctic Ocean in a changing climate

    NASA Astrophysics Data System (ADS)

    Ding, Y.

    2015-12-01

    Arctic climate is characterized by strong interannual to interannual/decadal variability involving interactions with the overlying atmosphere as well as exchanges with the Pacific and Atlantic Oceans. By increasing the geographic area of contact as well as by changing the mean stratification and overturning circulation future reductions of sea ice cover offers the potential to enhance and alter these interactions. This study begins with a comparison of simulated and historical interannual/decadal variability in the Arctic Ocean, and the relative importance of local atmospheric heating and ocean heat convergence, as they appear in a collection of CMIP5 model simulations. This analysis reveals that the models can be classified into two groups depending on their responses. Then we examine the changes in this variability over the coming centuries as simulated by the models, which reveal dramatic changes to the strength and frequency of the variability as the sea ice retreats. The connections to interannual/decadal variations of the overturning circulation and to atmospheric weather patterns will be discussed.

  4. Modelling the impact of climate change on the atmospheric transport and the fate of persistent organic pollutants in the Arctic

    NASA Astrophysics Data System (ADS)

    Hansen, K. M.; Christensen, J. H.; Geels, C.; Silver, J. D.; Brandt, J.

    2015-06-01

    The Danish Eulerian Hemispheric Model (DEHM) was applied to investigate how projected climate changes will affect the atmospheric transport of 13 persistent organic pollutants (POPs) to the Arctic and their environmental fate within the Arctic. Three sets of simulations were performed, one with present day emissions and initial environmental concentrations from a 20-year spin-up simulation, one with present day emissions and with initial environmental concentrations set to zero and one without emissions but with initial environmental concentrations from the 20-year spin-up simulation. Each set of simulations consisted of two 10-year time slices representing the present (1990-2000) and future (2090-2100) climate conditions. DEHM was driven using meteorological input from the global circulation model, ECHAM/MPI-OM, simulating the SRES (Special Report on Emissions Scenarios) A1B climate scenario. Under the applied climate and emission scenarios, the total mass of all compounds was predicted to be up to 55 % lower across the Northern Hemisphere at the end of the 2090s than in the 1990s. The mass of HCHs within the Arctic was predicted to be up to 38 % higher, whereas the change in mass of the PCBs was predicted to range from 38 % lower to 17 % higher depending on the congener and the applied initial environmental concentrations. The results of this study also indicate that contaminants with no or a short emission history will be more rapidly transported to and build up in the arctic environment in a future warmer climate. The process that dominates the environmental behaviour of POPs in the Arctic under a future warmer climate scenario is the shift in mass of POPs from the surface media to the atmosphere induced by the higher mean temperature. This is to some degree counteracted by higher degradation rates also following the higher mean temperature. The more dominant of these two processes depends on the physical-chemical properties of the compounds. Previous model

  5. COLLABORATIVE RESEARCH: TOWARDS ADVANCED UNDERSTANDING AND PREDICTIVE CAPABILITY OF CLIMATE CHANGE IN THE ARCTIC USING A HIGH-RESOLUTION REGIONAL ARCTIC CLIMATE SYSTEM MODEL

    SciTech Connect

    Gutowski, William J.

    2013-02-07

    The motivation for this project was to advance the science of climate change and prediction in the Arctic region. Its primary goals were to (i) develop a state-of-the-art Regional Arctic Climate system Model (RACM) including high-resolution atmosphere, land, ocean, sea ice and land hydrology components and (ii) to perform extended numerical experiments using high performance computers to minimize uncertainties and fundamentally improve current predictions of climate change in the northern polar regions. These goals were realized first through evaluation studies of climate system components via one-way coupling experiments. Simulations were then used to examine the effects of advancements in climate component systems on their representation of main physics, time-mean fields and to understand variability signals at scales over many years. As such this research directly addressed some of the major science objectives of the BER Climate Change Research Division (CCRD) regarding the advancement of long-term climate prediction.

  6. Modeling the Arctic climate system using the regional climate model HIRHAM

    NASA Astrophysics Data System (ADS)

    Rinke, A.; Dethloff, K.; Dorn, W.; Matthes, H.; Mielke, M.; Klaus, D.

    2012-12-01

    The regional climate model HIRHAM is used as a tool for coupled modeling of the Arctic climate system. Various approaches are pursued which will finally be combined into a regional Earth system model. Compared to data from the 35th North Pole drifting station of 2007-2008, the HIRHAM model has been evaluated over the central Arctic concerning atmospheric boundary layer and cloud cover. Modifications of the stability functions impact the regional circulation but cannot satisfactorily improve the boundary layer structure. A prognostic statistical cloud scheme performs better than a relative humidity-based scheme. With the coupled atmosphere-ocean-ice model HIRHAM-NAOSIM, ensemble simulations were conducted for the period 1948-2008. It is demonstrated that a realistic simulation of the atmospheric circulation and its internal variability is required to reproduce the observed sea ice extent in summer. Alongside, the internal variability of the atmospheric HIRHAM model is quantified, also based on ensemble simulations for 1979-2008. Coupled atmosphere-land HIRHAM simulations for future Arctic climate scenarios are discussed with respect to the influence of vegetation changes as well as its implications for frozen ground conditions.

  7. Climate change in the North American Arctic: A one health perspective

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Climate change is expected to increase the prevalence of acute and chronic diseases among human and animal populations within the Arctic and sub-Arctic latitudes of North America. Warmer temperatures are expected to increase disease risks from food-borne pathogens, water-borne diseases, and vector-...

  8. Biased thermohaline exchanges with the Arctic across the Iceland-Faroe Ridge in ocean climate models

    NASA Astrophysics Data System (ADS)

    Olsen, S. M.; Hansen, B.; Østerhus, S.; Quadfasel, D.; Valdimarsson, H.

    2016-04-01

    The northern limb of the Atlantic thermohaline circulation and its transport of heat and salt towards the Arctic strongly modulate the climate of the Northern Hemisphere. The presence of warm surface waters prevents ice formation in parts of the Arctic Mediterranean, and ocean heat is directly available for sea-ice melt, while salt transport may be critical for the stability of the exchanges. Through these mechanisms, ocean heat and salt transports play a disproportionally strong role in the climate system, and realistic simulation is a requisite for reliable climate projections. Across the Greenland-Scotland Ridge (GSR) this occurs in three well-defined branches where anomalies in the warm and saline Atlantic inflow across the shallow Iceland-Faroe Ridge (IFR) have been shown to be particularly difficult to simulate in global ocean models. This branch (IF-inflow) carries about 40 % of the total ocean heat transport into the Arctic Mediterranean and is well constrained by observation during the last 2 decades but associated with significant inter-annual fluctuations. The inconsistency between model results and observational data is here explained by the inability of coarse-resolution models to simulate the overflow across the IFR (IF-overflow), which feeds back onto the simulated IF-inflow. In effect, this is reduced in the model to reflect only the net exchange across the IFR. Observational evidence is presented for a substantial and persistent IF-overflow and mechanisms that qualitatively control its intensity. Through this, we explain the main discrepancies between observed and simulated exchange. Our findings rebuild confidence in modelled net exchange across the IFR, but reveal that compensation of model deficiencies here through other exchange branches is not effective. This implies that simulated ocean heat transport to the Arctic is biased low by more than 10 % and associated with a reduced level of variability, while the quality of the simulated salt

  9. Permafrost-Affected Soils of the Russian Arctic and their Carbon Pools

    NASA Astrophysics Data System (ADS)

    Zubrzycki, S.; Kutzbach, L.; Pfeiffer, E.-M.

    2014-02-01

    Permafrost-affected soils have accumulated enormous pools of organic matter during the Quaternary Period. The area occupied by these soils amounts to more than 8.6 million km2, which is about 27% of all land areas north of 50° N. Therefore, permafrost-affected soils are considered to be one of the most important cryosphere elements within the climate system. Due to the cryopedogenic processes that form these particular soils and the overlying vegetation that is adapted to the arctic climate, organic matter has accumulated to the present extent of up to 1024 Pg (1 Pg = 1015 g = 1 Gt) of soil organic carbon stored within the uppermost three meters of ground. Considering the observed progressive climate change and the projected polar amplification, permafrost-affected soils will undergo fundamental property changes. Higher turnover and mineralization rates of the organic matter are consequences of these changes, which are expected to result in an increased release of climate-relevant trace gases into the atmosphere. As a result, permafrost regions with their distinctive soils are likely to trigger an important tipping point within the global climate system, with additional political and social implications. The controversy of whether permafrost regions continue accumulating carbon or already function as a carbon source remains open until today. An increased focus on this subject matter, especially in underrepresented Siberian regions, could contribute to a more robust estimation of the soil organic carbon pool of permafrost regions and at the same time improve the understanding of the carbon sink and source functions of permafrost-affected soils.

  10. Assessing the Global and Arctic Transport of Polychlorinated Biphenyls Under Present and Future Climate and Emissions

    NASA Astrophysics Data System (ADS)

    Friedman, C. L.; Selin, N. E.

    2014-12-01

    We simulate the present and potential future atmospheric transport and fate of polychlorinated biphenyls (PCBs), using the global chemical transport model GEOS-Chem. PCBs are toxic, persistent, and bioaccumulative chemicals whose production and use have been banned internationally. PCBs continue to cycle through the global atmosphere, however, because of their persistence, passive emissions from remaining stocks, and release from natural storage reservoirs such as oceans or soils. In particular, PCBs have been shown to transport long distances in the atmosphere to locations remote from emissions, such as the Arctic, where they can accumulate in wildlife and humans, putting health at risk. Previous studies have suggested that PCBs may be remobilized in a changing climate because higher temperatures will cause greater re-emissions from surface reservoirs. Here, we modify GEOS-Chem to simulate atmospheric PCB transport and investigate the relative effects of predicted climate changes and projected declines in primary emissions, especially on transport to the Arctic. We quantify changes in atmospheric concentrations of two PCBs (CB28 and CB 153) under 2050 climate ("FC"); 2050 emissions ("FE"); and 2050 climate and emissions combined ("FCFE"); relative to a 2000 climate, 2000 emissions control scenario, and determine the major processes affecting these changes. In the version of the model presented here, only soil-atmosphere surface interactions are considered, though future versions will include interaction with other surface media. Our results suggest projected 2050 emissions will play a stronger role than 2050 climate in controlling PCB concentrations of different volatilities. Temperature increases under FC cause increases in emissions of only 4% at most, resulting in negligible concentration changes relative to the FE scenario, in which primary emissions are projected to decline to <0.05% of present-day. Thus, the concentrations in the combined FCFE scenario are

  11. Evidence and Implications of Recent Climate Change in Terrestrial Regions of the Arctic

    NASA Astrophysics Data System (ADS)

    Hinzman, L. D.; Bettez, N.; Chapin, F. S.; Dyurgerov, M.; Fastie, C.; Griffith, D. B.; Hope, A.; Huntington, H. P.; Jensen, A.; Kane, D. L.; Kofinas, G.; Lynch, A.; Lloyd, A.; McGuire, A. D.; Nelson, F. E.; Osterkamp, T.; Oechel, W. C.; Racine, C.; Romanovsky, V. E.; Schimel, J.; Stow, D.; Sturm, M.; Tweedie, C. E.; Vourlitis, G.; Walker, M.; Webber, P. J.; Welker, J.; Winker, K.; Yoshikawa, K.

    2002-12-01

    Are changes occurring in the polar terrestrial regime? Is the distribution of permafrost and Arctic region freeze and thaw changing? Is the hydrology of Arctic terrestrial regions changing? Are significant changes occurring in the distribution and productivity of high-latitude vegetation? If one examines any individual scientific discipline, evidence of climate change in arctic regions offers only pieces of the puzzle. Here we present a broad array of evidence to provide a convincing case of change in the arctic climate and a system-wide response of terrestrial processes. The thermal regime of the Arctic holds unique characteristics and consequently will display marked changes in response to climate warming. In many cases, threshold changes will occur in physical systems proceeding from permanently frozen to periodically thawed. Dramatic changes also accompany biological systems adapting to an evolving environment. In the last 25 to 400 years a wide range of changes in the Arctic have been detected. In many cases, these changes started, or accelerated, in the mid-1970s. Some of the changes, like later freeze-up and earlier break-up of arctic rivers and lakes, mirror arctic-wide and even global increases in air temperature. Others document more subtle or complex responses of the arctic system as it adapts to current and longer-term trends in climate. Since the arctic system is particularly sensitive to changes in rain- and snowfall, timing of freeze-up and break-up, and the intensity of storm activity, it is likely that much of what has been documented to date, and will be observed in the future, arises from changes in these forcing fields. Unfortunately, compared with temperature, they are poorly known. Regardless of the driving forces, however, the combined observations and documentation offer diffuse but substantial evidence that the arctic system may be entering a state not seen before in recent history.

  12. Dynamics of Arctic and Sub-Arctic Climate and Atmospheric Circulation: Diagnosis of Mechanisms and Biases Using Data Assimilation

    SciTech Connect

    Eric T. DeWeaver

    2010-02-17

    The overall goal of work performed under this grant is to enhance understanding of simulations of present-day climate and greenhouse gas-induced climate change. The examination of present-day climate also includes diagnostic intercomparison of model simulations and observed mean climate and climate variability using reanalysis and satellite datasets. Enhanced understanding is desirable 1) as a prerequisite for improving simulations; 2) for assessing the credibility of model simulations and their usefulness as tools for decision support; and 3) as a means to identify robust behaviors which commonly occur over a wide range of models, and may yield insights regarding the dominant physical mechanisms which determine mean climate and produce climate change. A further objective is to investigate the use of data assimilation as a means for examining and correcting model biases. Our primary focus is on the Arctic, but the scope of the work was expanded to include the global climate system.

  13. Modelling impact of climate change on atmospheric transport and fate of persistent organic pollutants in the Arctic

    NASA Astrophysics Data System (ADS)

    Hansen, K. M.; Christensen, J. H.; Geels, C.; Silver, J. D.; Brandt, J.

    2015-03-01

    The Danish Eulerian Hemispheric Model (DEHM) was applied to investigate how projected climate changes will affect the atmospheric transport of 13 persistent organic pollutants (POPs) to the Artic and their environmental fate within the Arctic. Two sets of simulations were performed, one with initial environmental concentrations from a 20 year spin-up simulation and one with initial environmental concentrations set to zero. Each set of simulations consisted of two ten-year time slices representing the present (1990-2000) and future (2090-2100) climate conditions. The same POP emissions were applied in all simulations to ensure that the difference in predicted concentrations for each set of simulations only arises from the difference in climate input. DEHM was driven using meteorological input from the global circulation model, ECHAM/MPI-OM, simulating the SRES A1B climate scenario. Under the applied climate and emission scenarios, the total mass of all compounds was predicted to be up to 20% higher across the Northern Hemisphere. The mass of HCHs within the Arctic was predicted to be up to 39% higher, whereas the change in mass of the PCBs was predicted to range from 14% lower to 17% higher depending on the congener and the applied initial environmental concentrations. The results of this study also indicate that contaminants with no or a short emission history will be more rapidly transported to and build up in the arctic environment in a future warmer climate. The process that dominates the environmental behaviour of POPs in the Arctic under a future warmer climate scenario is the shift in mass of POPs from the surface media to the atmosphere induced by the higher mean temperature. This is to some degree counteracted by higher degradation rates also following the higher mean temperature. The more dominant of these two processes depend on the physical-chemical properties of the compounds. Previous model studies have predicted that the effect of a changed climate on

  14. On the Role of Sea Ice Deformations in Arctic Climate Change

    NASA Astrophysics Data System (ADS)

    Maslowski, Wieslaw; Osinski, Robert; Roberts, Andrew; DiMaggio, Dominic

    2015-04-01

    Understanding air-sea interactions and their effects on arctic climate change requires comprehensive knowledge of the sea ice dynamics and thermodynamics at a process level. While significant advancement has been made for example in understanding and model representation of sea ice rheology, surface albedo and ice-albedo feedback, there are other processes such as sea ice deformations, which require further studies and model improvement. Of particular potential interest are leads, which control winter air-sea heat exchange and buoyancy input into the ocean, or sea ice ridging and shearing, which affect the ice-ocean coupling. Their importance in arctic climate change under an increasing first-year ice cover is yet to be determined, as global climate models commonly do not resolve such sea ice features at their actual scale, magnitude and frequency and stand-alone high-resolution atmosphere or ice-ocean models do not allow studies of air-sea-ice interactions. We use the Regional Arctic System Model (RASM), which is a fully coupled, high-resolution regional climate model, to study sea ice deformation processes and resulting coupling across the air-sea interface. RASM includes the Weather Research and Forecasting (WRF) atmospheric model, the Parallel Ocean Program (POP), the Community Ice Model (CICE) and the Variable Infiltration Capacity (VIC) land hydrology model. It is configured for the pan-Arctic region at an eddy-permitting resolution of 1/12° for the ice-ocean and 50 km for the atmosphere-land model components. In addition, all RASM components are coupled at high frequency, i.e. at a 20-minute time step. The sea ice component has been upgraded to the Los Alamos Community Ice Model version 5 (CICE5), which allows either Elastic-Viscous-Plastic (EVP) or a new anisotropic (EPA) rheology and incorporates form drag to more realistically represent sea ice morphology and estimate ice-ocean and ice-atmosphere stresses. Results from multiple RASM simulations, using

  15. Arctic marine climate of the early nineteenth century

    NASA Astrophysics Data System (ADS)

    Brohan, P.; Ward, C.; Willetts, G.; Wilkinson, C.; Allan, R.; Wheeler, D.

    2010-02-01

    The climate of the early nineteenth century is likely to have been significantly cooler than that of today, as it was a period of low solar activity (the Dalton minimum) and followed a series of large volcanic eruptions. Proxy reconstructions of the temperature of the period do not agree well on the size of the temperature change, so other observational records from the period are particularly valuable. Weather observations have been extracted from the reports of the noted whaling captain William Scoresby Jr., and from the records of a series of Royal Navy expeditions to the Arctic, preserved in the UK National Archives. They demonstrate that marine climate in 1810-25 was marked by consistently cold summers, with abundant sea-ice. But although the period was significantly colder than the modern average, there was a lot of variability: in the Greenland Sea the summers following the Tambora eruption (1816 and 1817) were noticeably warmer, and had lower sea-ice coverage, than the years immediately preceding them; and the sea-ice coverage in Lancaster Sound in 1819 and 1820 was low even by modern standards.

  16. Arctic marine climate of the early nineteenth century

    NASA Astrophysics Data System (ADS)

    Brohan, P.; Ward, C.; Willetts, G.; Wilkinson, C.; Allan, R.; Wheeler, D.

    2010-05-01

    The climate of the early nineteenth century is likely to have been significantly cooler than that of today, as it was a period of low solar activity (the Dalton minimum) and followed a series of large volcanic eruptions. Proxy reconstructions of the temperature of the period do not agree well on the size of the temperature change, so other observational records from the period are particularly valuable. Weather observations have been extracted from the reports of the noted whaling captain William Scoresby Jr., and from the records of a series of Royal Navy expeditions to the Arctic, preserved in the UK National Archives. They demonstrate that marine climate in 1810-1825 was marked by consistently cold summers, with abundant sea-ice. But although the period was significantly colder than the modern average, there was considerable variability: in the Greenland Sea the summers following the Tambora eruption (1816 and 1817) were noticeably warmer, and had less sea-ice coverage, than the years immediately preceding them; and the sea-ice coverage in Lancaster Sound in 1819 and 1820 was low even by modern standards.

  17. Coupled climate network analysis of multidecadal dynamics in the Arctic

    NASA Astrophysics Data System (ADS)

    Wiedermann, M.; Donges, J. F.; Heitzig, J.; Kurths, J.

    2012-04-01

    Climate network analysis provides a powerful tool for investigating the correlation structure of the dynamical system Earth. Elements of time series analysis and the theory of complex networks are combined to give new insights into the dynamics of the climate system by delivering a spatially resolved image of the underlying correlation structure from which the network is constructed. Recent results have indicated a possible correlation between the Atlantic Multidecadal Oscillation (AMO) and the Pacific Decadal Oscillation (PDO) with a time lag of 15 to 30 years. However, identifying the involved physical mechanisms remains an open problem of ocean science and atmospheric research. We perform a climate network analysis aiming at assessing the importance of the Arctic for this connection between North Atlantic and North Pacific. As storm tracks were suggested to play a role and the large delay between AMO and PDO points to oceanic processes at work, we focus on analyzing the coupling structure between oceanic sea surface temperature (SST) and atmospheric sea level pressure (SAP) as well as geopotential height (GPH) fields. We employ the recently developed theory of interacting networks, with the corresponding statistical cross-network measures, that enables us to study the properties of a coupled climate network that divides into several subnetworks representing horizontal fields of different observables. As the analysis is performed in a region close to the north pole one has to bear in mind that climatological datasets are often arranged on a rectangular grid such that the density of nodes increases rapidly towards the poles. To correct for the distortions in our results resulting from this inhomogenous node density, we refine the cross-network measures in a way that enables us to assign every node with an individual weight according to the area that the node represents on the Earth's surface. This method has already been applied to the standard set of measures

  18. The effect on Arctic climate of atmospheric meridional energy-transport changes studied based on the CESM climate model

    NASA Astrophysics Data System (ADS)

    Grand Graversen, Rune

    2016-04-01

    The Arctic amplification of global warming and the pronounced Arctic sea-ice retreat constitute some of the most alarming signs of global climate change. These Arctic changes are likely a consequence of a combination of several processes, for instance enhanced uptake of solar radiation in the Arctic due to a lowering of the planetary albedo, and increase in the local Arctic greenhouse effect due to enhanced moister flux from lower latitudes. Many of the proposed processes appear to be dependent on each other, for instance an increase in water-vapour advection to the Arctic enhances the greenhouse effect in the Arctic and the longwave radiation to the surface which melts the sea ice and causes an increase in absorption of solar radiation. The effects of albedo changes have been investigated in earlier studies based on model experiments designed to examine these effects specifically. Here we instead focus on the effects of meridional transport changes into the Arctic, both of water vapour and dry-static energy. Hence we here present results of model experiments with the CESM climate model designed specifically to extract the effects of the changes of the two transport components.

  19. Severity of climate change dictates the direction of biophysical feedbacks of vegetation change to Arctic climate

    NASA Astrophysics Data System (ADS)

    Zhang, Wenxin; Jansson, Christer; Miller, Paul; Smith, Ben; Samuelsson, Patrick

    2014-05-01

    Vegetation-climate feedbacks induced by vegetation dynamics under climate change alter biophysical properties of the land surface that regulate energy and water exchange with the atmosphere. Simulations with Earth System Models applied at global scale suggest that the current warming in the Arctic has been amplified, with large contributions from positive feedbacks, dominated by the effect of reduced surface albedo as an increased distribution, cover and taller stature of trees and shrubs mask underlying snow, darkening the surface. However, these models generally employ simplified representation of vegetation dynamics and structure and a coarse grid resolution, overlooking local or regional scale details determined by diverse vegetation composition and landscape heterogeneity. In this study, we perform simulations using an advanced regional coupled vegetation-climate model (RCA-GUESS) applied at high resolution (0.44×0.44° ) over the Arctic Coordinated Regional Climate Downscaling Experiment (CORDEX-Arctic) domain. The climate component (RCA4) is forced with lateral boundary conditions from EC-EARTH CMIP5 simulations for three representative concentration pathways (RCP 2.6, 4.5, 8.5). Vegetation-climate response is simulated by the individual-based dynamic vegetation model (LPJ-GUESS), accounting for phenology, physiology, demography and resource competition of individual-based vegetation, and feeding variations of leaf area index and vegetative cover fraction back to the climate component, thereby adjusting surface properties and surface energy fluxes. The simulated 2m air temperature, precipitation, vegetation distribution and carbon budget for the present period has been evaluated in another paper. The purpose of this study is to elucidate the spatial and temporal characteristics of the biophysical feedbacks arising from vegetation shifts in response to different CO2 concentration pathways and their associated climate change. Our results indicate that the

  20. Arctic Warmth Becomes a Mid-Latitude Chill: Using Online Data To Teach Climate Change Science

    NASA Astrophysics Data System (ADS)

    Eichorn, David N.

    Climate change education is a growing sub-discipline of science education. This research reports on the use of the fundamental principles of atmospheric science to explain the potential impact of regional climate change across global latitudes. Since the Arctic is responding to climate change faster than any other place on earth, it offers us a real-time opportunity to teach the larger scale impacts of abrupt regional scale change. In this research I merged elements of both the atmospheric and climate sciences into an online course. The course uses principles of meteorology to teach climate change science and demonstrate cause and effect relationships within the atmosphere. Students learn how climate change in one part of the world impacts weather elsewhere through the use of animated and descriptive video lectures that explain basic atmospheric thermodynamics processes. This paper includes a lesson plan that shows how climatic warming in the Arctic causes colder US winter weather. Formative and summative evaluations taken from course evaluations and exams suggest using meteorology to teach climate change is an effective way to educate students in high school and undergraduate college level courses about cross latitudinal influences of climate change. Keywords: Climate Change, Global Warming, Arctic, Climate Literacy, Lesson Plan, Arctic Oscillation, Education

  1. On the Influence of North Pacific Sea Surface Temperature on the Arctic Winter Climate

    NASA Technical Reports Server (NTRS)

    Hurwitz, Margaret M.; Newman, P. A.; Garfinkel, C. I.

    2012-01-01

    Differences between two ensembles of Goddard Earth Observing System Chemistry-Climate Model simulations isolate the impact of North Pacific sea surface temperatures (SSTs) on the Arctic winter climate. One ensemble of extended winter season forecasts is forced by unusually high SSTs in the North Pacific, while in the second ensemble SSTs in the North Pacific are unusually low. High Low differences are consistent with a weakened Western Pacific atmospheric teleconnection pattern, and in particular, a weakening of the Aleutian low. This relative change in tropospheric circulation inhibits planetary wave propagation into the stratosphere, in turn reducing polar stratospheric temperature in mid- and late winter. The number of winters with sudden stratospheric warmings is approximately tripled in the Low ensemble as compared with the High ensemble. Enhanced North Pacific SSTs, and thus a more stable and persistent Arctic vortex, lead to a relative decrease in lower stratospheric ozone in late winter, affecting the April clear-sky UV index at Northern Hemisphere mid-latitudes.

  2. Did the Arctic Ice Recover? Demographics of True and False Climate Facts

    NASA Astrophysics Data System (ADS)

    Hamilton, L.

    2012-12-01

    Beliefs about climate change divide the U.S. public along party lines more distinctly than hot social issues. Research finds that better educated or informed respondents are more likely to align with their parties on climate change. This information-elite polarization resembles a process of biased assimilation first described in psychological experiments. In nonexperimental settings, college graduates could be prone to biased assimilation if they more effectively acquire information that supports their beliefs. Recent national and statewide survey data show response patterns consistent with biased assimilation (and biased guessing) contributing to the correlation observed between climate beliefs and knowledge. The survey knowledge questions involve key, uncontroversial observations such as whether the area of late-summer Arctic sea ice has declined, increased, or declined and then recovered to what it was 30 years ago. Correct answers are predicted by education, and some wrong answers (e.g., more ice) have predictors that suggest lack of knowledge. Other wrong answers (e.g., ice recovered) are predicted by political and belief factors instead. Responses show indications of causality in both directions: science information affecting climate beliefs, but also beliefs affecting the assimilation of science information.; ;

  3. Diverging Plant and Ecosystem Strategies in Response to Climate Change in the High Arctic

    NASA Astrophysics Data System (ADS)

    Maseyk, K. S.; Welker, J. M.; Czimczik, C. I.; Lupascu, M.; Lett, C.; Seibt, U. H.

    2014-12-01

    Increasing summer precipitation means Arctic growing seasons are becoming wetter as well as warmer, but the effect of these coupled changes on tundra ecosystem functioning remains largely unknown. We have determined how warmer and wetter summers affect coupled carbon-water cycling in a High Arctic polar semi-desert ecosystem in NW Greenland. Measurements of ecosystem CO2 and water fluxes throughout the growing season and leaf ecophysiological traits (gas exchange, morphology, leaf chemistry) were made at a long-term climate change experiment. After 9 years of exposure to warmer (+ 4°C) and / or wetter (+ 50% precipitation) treatments, we found diverging plant strategies between the responses to warming with or without an increase in summer precipitation. Warming alone resulted in an increase in leaf nitrogen, mesophyll conductance and leaf-mass per area and higher rates of leaf-level photosynthesis, but with warming and wetting combined leaf traits remain largely unchanged. However, total leaf area increased with warming plus wetting but was unchanged with warming alone. The combined effect of these leaf trait and canopy adjustments is a decrease in ecosystem water-use efficiency (the ratio of net productivity to evapotranspiration) with warming only, but a substantial increase with combined warming and wetting. We conclude that increasing summer precipitation will alter tundra ecohydrological responses to warming; that leaf-level changes in ecophysiological traits have an upward cascading consequence for ecosystem and land surface-climate interactions; and the current relative resistance of High Arctic ecosystems to warming may mask biochemical and carbon cycling changes already underway.

  4. Dangerous climate change and the importance of adaptation for the Arctic's Inuit population

    NASA Astrophysics Data System (ADS)

    Ford, James D.

    2009-04-01

    The Arctic's climate is changing rapidly, to the extent that 'dangerous' climate change as defined by the United Nations Framework on Climate Change might already be occurring. These changes are having implications for the Arctic's Inuit population and are being exacerbated by the dependence of Inuit on biophysical resources for livelihoods and the low socio-economic-health status of many northern communities. Given the nature of current climate change and projections of a rapidly warming Arctic, climate policy assumes a particular importance for Inuit regions. This paper argues that efforts to stabilize and reduce greenhouse gas emissions are urgent if we are to avoid runaway climate change in the Arctic, but unlikely to prevent changes which will be dangerous for Inuit. In this context, a new policy discourse on climate change is required for Arctic regions—one that focuses on adaptation. The paper demonstrates that states with Inuit populations and the international community in general has obligations to assist Inuit to adapt to climate change through international human rights and climate change treaties. However, the adaptation deficit, in terms of what we know and what we need to know to facilitate successful adaptation, is particularly large in an Arctic context and limiting the ability to develop response options. Moreover, adaptation as an option of response to climate change is still marginal in policy negotiations and Inuit political actors have been slow to argue the need for adaptation assistance. A new focus on adaptation in both policy negotiations and scientific research is needed to enhance Inuit resilience and reduce vulnerability in a rapidly changing climate.

  5. Rapid Arctic Changes due to Infrastructure and Climate (RATIC) in the Russian North

    NASA Astrophysics Data System (ADS)

    Walker, D. A.; Kofinas, G.; Raynolds, M. K.; Kanevskiy, M. Z.; Shur, Y.; Ambrosius, K.; Matyshak, G. V.; Romanovsky, V. E.; Kumpula, T.; Forbes, B. C.; Khukmotov, A.; Leibman, M. O.; Khitun, O.; Lemay, M.; Allard, M.; Lamoureux, S. F.; Bell, T.; Forbes, D. L.; Vincent, W. F.; Kuznetsova, E.; Streletskiy, D. A.; Shiklomanov, N. I.; Fondahl, G.; Petrov, A.; Roy, L. P.; Schweitzer, P.; Buchhorn, M.

    2015-12-01

    The Rapid Arctic Transitions due to Infrastructure and Climate (RATIC) initiative is a forum developed by the International Arctic Science Committee (IASC) Terrestrial, Cryosphere, and Social & Human working groups for developing and sharing new ideas and methods to facilitate the best practices for assessing, responding to, and adaptively managing the cumulative effects of Arctic infrastructure and climate change. An IASC white paper summarizes the activities of two RATIC workshops at the Arctic Change 2014 Conference in Ottawa, Canada and the 2015 Third International Conference on Arctic Research Planning (ICARP III) meeting in Toyama, Japan (Walker & Pierce, ed. 2015). Here we present an overview of the recommendations from several key papers and posters presented at these conferences with a focus on oil and gas infrastructure in the Russian north and comparison with oil development infrastructure in Alaska. These analyses include: (1) the effects of gas- and oilfield activities on the landscapes and the Nenets indigenous reindeer herders of the Yamal Peninsula, Russia; (2) a study of urban infrastructure in the vicinity of Norilsk, Russia, (3) an analysis of the effects of pipeline-related soil warming on trace-gas fluxes in the vicinity of Nadym, Russia, (4) two Canadian initiatives that address multiple aspects of Arctic infrastructure called Arctic Development and Adaptation to Permafrost in Transition (ADAPT) and the ArcticNet Integrated Regional Impact Studies (IRIS), and (5) the effects of oilfield infrastructure on landscapes and permafrost in the Prudhoe Bay region, Alaska.

  6. Adaptive strategies and life history characteristics in a warming climate: salmon in the Arctic?

    USGS Publications Warehouse

    Nielsen, Jennifer L.; Ruggerone, Gregory T.; Zimmerman, Christian E.

    2013-01-01

    In the warming Arctic, aquatic habitats are in flux and salmon are exploring their options. Adult Pacific salmon, including sockeye (Oncorhynchus nerka), coho (O. kisutch), Chinook (O. tshawytscha), pink (O. gorbuscha) and chum (O. keta) have been captured throughout the Arctic. Pink and chum salmon are the most common species found in the Arctic today. These species are less dependent on freshwater habitats as juveniles and grow quickly in marine habitats. Putative spawning populations are rare in the North American Arctic and limited to pink salmon in drainages north of Point Hope, Alaska, chum salmon spawning rivers draining to the northwestern Beaufort Sea, and small populations of chum and pink salmon in Canada’s Mackenzie River. Pacific salmon have colonized several large river basins draining to the Kara, Laptev and East Siberian seas in the Russian Arctic. These populations probably developed from hatchery supplementation efforts in the 1960’s. Hundreds of populations of Arctic Atlantic salmon (Salmo salar) are found in Russia, Norway and Finland. Atlantic salmon have extended their range eastward as far as the Kara Sea in central Russian. A small native population of Atlantic salmon is found in Canada’s Ungava Bay. The northern tip of Quebec seems to be an Atlantic salmon migration barrier for other North American stocks. Compatibility between life history requirements and ecological conditions are prerequisite for salmon colonizing Arctic habitats. Broad-scale predictive models of climate change in the Arctic give little information about feedback processes contributing to local conditions, especially in freshwater systems. This paper reviews the recent history of salmon in the Arctic and explores various patterns of climate change that may influence range expansions and future sustainability of salmon in Arctic habitats. A summary of the research needs that will allow informed expectation of further Arctic colonization by salmon is given.

  7. Optical Properties and Climate Impacts of Tropospheric Aerosols that Undergo Long-Range Transport to the Arctic

    NASA Astrophysics Data System (ADS)

    Quinn, P.; Bates, T.; Coffman, D.; Schulz, K.; Shank, L.; Jefferson, A.; Ogren, J.; Burkhart, J.; Shaw, G.

    2009-04-01

    Tropospheric aerosol particles undergo long range transport from the mid-latitudes to the Arctic each winter and spring. Once in the Arctic, aerosols may impact regional climate in several ways. Aerosols can affect climate directly by scattering and absorbing incoming solar radiation and indirectly by acting as cloud condensation nuclei and altering cloud properties. In addition, absorbing aerosol that is deposited onto ice and snow can lower the surface albedo and enhance the ice-albedo feedback mechanism. Measurements of aerosol properties relevant to climate forcing (chemical composition, light scattering, and light absorption) have been made by NOAA at Barrow, AK for over a decade. Measurements of aerosol chemical composition have been made over the same time period at the three more southern Alaskan sites of Poker Flat, Denali National Park, and Homer. In addition, in March and April of 2008, aerosol measurements were made during a NOAA research cruise (ICEALOT) to the Greenland, Norwegian and Barents Seas. Onboard the ship, measurements were made of aerosol optical and cloud nucleating properties. Results from the long-term measurements and ICEALOT will be presented in order to describe trends and climate-relevant properties of aerosol particles transported to the Arctic.

  8. Regional Arctic System Model (RASM): A Tool to Advance Understanding and Prediction of Arctic Climate Change at Process Scales

    NASA Astrophysics Data System (ADS)

    Maslowski, W.; Roberts, A.; Osinski, R.; Brunke, M.; Cassano, J. J.; Clement Kinney, J. L.; Craig, A.; Duvivier, A.; Fisel, B. J.; Gutowski, W. J., Jr.; Hamman, J.; Hughes, M.; Nijssen, B.; Zeng, X.

    2014-12-01

    The Arctic is undergoing rapid climatic changes, which are some of the most coordinated changes currently occurring anywhere on Earth. They are exemplified by the retreat of the perennial sea ice cover, which integrates forcing by, exchanges with and feedbacks between atmosphere, ocean and land. While historical reconstructions from Global Climate and Global Earth System Models (GC/ESMs) are in broad agreement with these changes, the rate of change in the GC/ESMs remains outpaced by observations. Reasons for that stem from a combination of coarse model resolution, inadequate parameterizations, unrepresented processes and a limited knowledge of physical and other real world interactions. We demonstrate the capability of the Regional Arctic System Model (RASM) in addressing some of the GC/ESM limitations in simulating observed seasonal to decadal variability and trends in the sea ice cover and climate. RASM is a high resolution, fully coupled, pan-Arctic climate model that uses the Community Earth System Model (CESM) framework. It uses the Los Alamos Sea Ice Model (CICE) and Parallel Ocean Program (POP) configured at an eddy-permitting resolution of 1/12° as well as the Weather Research and Forecasting (WRF) and Variable Infiltration Capacity (VIC) models at 50 km resolution. All RASM components are coupled via the CESM flux coupler (CPL7) at 20-minute intervals. RASM is an example of limited-area, process-resolving, fully coupled earth system model, which due to the additional constraints from lateral boundary conditions and nudging within a regional model domain facilitates detailed comparisons with observational statistics that are not possible with GC/ESMs. In this talk, we will emphasize the utility of RASM to understand sensitivity to variable parameter space, importance of critical processes, coupled feedbacks and ultimately to reduce uncertainty in arctic climate change projections.

  9. The role of an Arctic ice shelf in the climate of the MIS 6 glacial maximum (140 ka)

    NASA Astrophysics Data System (ADS)

    Colleoni, F.; Krinner, G.; Jakobsson, M.

    2010-12-01

    During the last decade, Arctic icebreaker and nuclear submarine expeditions have revealed large-scale Pleistocene glacial erosion on the Lomonosov Ridge, Chukchi Borderland and along the Northern Alaskan margin indicating that the glacial Arctic Ocean hosted large Antarctic-style ice shelves. Dating of sediment cores indicates that the most extensive and deepest ice grounding occurred during Marine Isotope Stage (MIS) 6. The precise extents of Pleistocene ice shelves in the Arctic Ocean are unknown but seem comparable to present existing Antarctic ice shelves. How would an Antarctic-style ice shelf in the MIS 6 Arctic Ocean influence the Northern Hemisphere climate? Could it have impacted on the surface mass balance (SMB) of the MIS 6 Eurasian ice sheet and contributed to its large southward extent? We use an Atmospheric General Circulation Model (AGCM) to investigate the climatic impacts of both a limited MIS 6 ice shelf covering portions of the Canada Basin and a fully ice shelf covered Arctic Ocean. The AGCM results show that both ice shelves cause a temperature cooling of about 3 °C over the Arctic Ocean mainly due to the combined effect of ice elevation and isolation from the underlying ocean heat fluxes stopping the snow cover from melting during summer. The calculated SMB of the ice shelves are positive. The ice front horizontal velocity of the Canada Basin ice shelf is estimated to ≈ 1 km yr -1 which is comparable to the recent measurements of the Ross ice shelf, Antarctica. The existence of a large continuous ice shelf covering the entire Arctic Ocean would imply a mean annual velocity of icebergs of ≈12 km yr -1 through the Fram Strait. Our modeling results show that both ice shelf configurations could be viable under the MIS 6 climatic conditions. However, the cooling caused by these ice shelves only affects the Arctic margins of the continental ice sheets and is not strong enough to significantly influence the surface mass balance of the entire MIS

  10. Improved Climate Prediction through a System Level Understanding of Arctic Terrestrial Ecosystems: Next Generation Ecosystem Experiments (NGEE-Arctic)*

    NASA Astrophysics Data System (ADS)

    Hubbard, S. S.; Graham, D. E.; Hinzman, L. D.; Liang, L.; Liljedahl, A.; Norby, R. J.; Rogers, A.; Rowland, J. C.; Thornton, P. E.; Torn, M. S.; Riley, W. J.; Wilson, C. J.; Wullschleger, S. D.

    2013-12-01

    Characterized by vast amounts of carbon stored in permafrost and a rapidly evolving landscape, the Arctic has emerged as an important focal point for the study of climate change. Although recognized as an ecosystem highly vulnerable to climate change, mechanisms that govern feedbacks between the terrestrial and climate system are not well understood. Increasing our confidence in climate projections for high-latitude regions of the world requires coordinated investigations that target improved process understanding and model representation of important ecosystem-climate feedbacks. The Next-Generation Ecosystem Experiments (NGEE-Arctic) seeks to address this challenge by quantifying the physical, chemical, and biological behavior of terrestrial ecosystems in Alaska. The NGEE-Arctic project is a large, multi-disciplinary activity sponsored by the Department of Energy, Office of Science. Recent NGEE-Arctic research has focused on the highly dynamic landscapes of the North Slope Arctic tundra where thaw lakes, drained thaw lake basins, and ice-rich polygonal ground offer distinct land units for investigation and modeling. The project is working on the Barrow Environmental Observatory to study interactions that drive critical climate feedbacks within these environments through greenhouse gas fluxes and changes in surface energy balance associated with permafrost degradation and the many other processes that arise as a result of these landscape dynamics. Ongoing are mechanistic studies in the field and in the laboratory; modeling of critical and interrelated water, nitrogen, carbon, and energy dynamics; and characterization of important interactions from molecular to landscape scales that drive feedbacks to the climate system. A suite of climate-, intermediate- and fine-scale models are being used to guide observations and interpret data, while characterization information and process studies serve to initialize state variables in models, provide new algorithms and

  11. The Rossby Centre Regional Atmospheric Climate Model part II: application to the Arctic climate.

    PubMed

    Jones, Colin G; Wyser, Klaus; Ullerstig, Anders; Willén, Ulrika

    2004-06-01

    The Rossby Centre regional climate model (RCA2) has been integrated over the Arctic Ocean as part of the international ARCMIP project. Results have been compared to observations derived from the SHEBA data set. The standard RCA2 model overpredicts cloud cover and downwelling longwave radiation, during the Arctic winter. This error was improved by introducing a new cloud parameterization, which significantly improves the annual cycle of cloud cover. Compensating biases between clear sky downwelling longwave radiation and longwave radiation emitted from cloud base were identified. Modifications have been introduced to the model radiation scheme that more accurately treat solar radiation interaction with ice crystals. This leads to a more realistic representation of cloud-solar radiation interaction. The clear sky portion of the model radiation code transmits too much solar radiation through the atmosphere, producing a positive bias at the top of the frequent boundary layer clouds. A realistic treatment of the temporally evolving albedo, of both sea-ice and snow, appears crucial for an accurate simulation of the net surface energy budget. Likewise, inclusion of a prognostic snow-surface temperature seems necessary, to accurately simulate near-surface thermodynamic processes in the Arctic. PMID:15264599

  12. Arctic climate response to decadally-paced explosive volcanism in CCSM3

    NASA Astrophysics Data System (ADS)

    Zhong, Y.; Miller, G. H.; Otto-Bliesner, B. L.; Ammann, C. M.; Holland, M. M.; Bailey, D. A.; Schneider, D. P.; Geirsdottir, A.; Marshall, S. J.

    2010-12-01

    It is well known that the Arctic is the most sensitive region to radiative forcing as a result of multiple positive feedbacks that are inherent to the Arctic climate system. Much less well known is its ability to sustain the climate response after removal of the radiative forcing. Using a fully-coupled general climate model - NCAR’s CCSM3 -we test whether four decadally-sequenced tropical volcanic eruptions may produce a climate response in the Arctic that persists much longer than the radiative perturbation. Our results suggest the interaction between Arctic sea ice and subpolar North Atlantic produces a strong feedback that allows Arctic Ocean sea ice to remain in an expanded state, consequently sustaining a cooling response on centennial timescales with certain initial conditions. The crucial dependence of the sea ice-ocean interaction on initial states in the subpolar North Atlantic demonstrates the importance of the initial conditions in forecasting or hindcasting the climate response. To examine the relevance of such a centennial-scale response to the recently documented irreversible ice cap expansion during early stages of the Little Ice Age in the Atlantic sector of the Arctic, we conduct a CCSM3 simulation where reconstructed volcanic aerosol forcing is prescribed, and then drive a regional ice-cap model with the large-scale fields from the CCSM3 simulation. Preliminary results suggest the four decadally-spaced eruptions in the late 13th century caused a general cooling over the Atlantic sector of Arctic Ocean and contiguous land area, which was sustained for 400 years under additional volcanic forcing at ~1450AD and late 16th century. We are currently evaluating whether the mass balance of ice caps in the Eastern Canadian Arctic became substantially more positive during this prolonged interval of reduced summer temperature as is indicated by the paleodata.

  13. Climate Change in the North American Arctic: A One Health Perspective.

    PubMed

    Dudley, Joseph P; Hoberg, Eric P; Jenkins, Emily J; Parkinson, Alan J

    2015-12-01

    Climate change is expected to increase the prevalence of acute and chronic diseases among human and animal populations within the Arctic and subarctic latitudes of North America. Warmer temperatures are expected to increase disease risks from food-borne pathogens, water-borne diseases, and vector-borne zoonoses in human and animal populations of Arctic landscapes. Existing high levels of mercury and persistent organic pollutant chemicals circulating within terrestrial and aquatic ecosystems in Arctic latitudes are a major concern for the reproductive health of humans and other mammals, and climate warming will accelerate the mobilization and biological amplification of toxic environmental contaminants. The adverse health impacts of Arctic warming will be especially important for wildlife populations and indigenous peoples dependent upon subsistence food resources from wild plants and animals. Additional research is needed to identify and monitor changes in the prevalence of zoonotic pathogens in humans, domestic dogs, and wildlife species of critical subsistence, cultural, and economic importance to Arctic peoples. The long-term effects of climate warming in the Arctic cannot be adequately predicted or mitigated without a comprehensive understanding of the interactive and synergistic effects between environmental contaminants and pathogens in the health of wildlife and human communities in Arctic ecosystems. The complexity and magnitude of the documented impacts of climate change on Arctic ecosystems, and the intimacy of connections between their human and wildlife communities, makes this region an appropriate area for development of One Health approaches to identify and mitigate the effects of climate warming at the community, ecosystem, and landscape scales. PMID:26070525

  14. Arctic sea ice response to atmospheric forcings with varying levels of anthropogenic warming and climate variability

    NASA Astrophysics Data System (ADS)

    Zhang, Jinlun; Steele, Michael; Schweiger, Axel

    2010-10-01

    Numerical experiments are conducted to project arctic sea ice responses to varying levels of future anthropogenic warming and climate variability over 2010-2050. A summer ice-free Arctic Ocean is likely by the mid-2040s if arctic surface air temperature (SAT) increases 4°C by 2050 and climate variability is similar to the past relatively warm two decades. If such a SAT increase is reduced by one-half or if a future Arctic experiences a range of SAT fluctuation similar to the past five decades, a summer ice-free Arctic Ocean would be unlikely before 2050. If SAT increases 4°C by 2050, summer ice volume decreases to very low levels (10-37% of the 1978-2009 summer mean) as early as 2025 and remains low in the following years, while summer ice extent continues to fluctuate annually. Summer ice volume may be more sensitive to warming while summer ice extent more sensitive to climate variability. The rate of annual mean ice volume decrease relaxes approaching 2050. This is because, while increasing SAT increases summer ice melt, a thinner ice cover increases winter ice growth. A thinner ice cover also results in a reduced ice export, which helps to further slow ice volume loss. Because of enhanced winter ice growth, arctic winter ice extent remains nearly stable and therefore appears to be a less sensitive climate indicator.

  15. Holocene glaciation and climate evolution of Baffin Island, Arctic Canada

    NASA Astrophysics Data System (ADS)

    Miller, Gifford H.; Wolfe, Alexander P.; Briner, Jason P.; Sauer, Peter E.; Nesje, Atle

    2005-08-01

    Lake sediment cores and cosmogenic exposure (CE) dates constrain the pattern of deglaciation and evolution of climate across Baffin Island since the last glacial maximum (LGM). CE dating of erratics demonstrates that the northeastern coastal lowlands became ice-free ca.14 ka as the Laurentide Ice Sheet (LIS) receded from its LGM margin on the continental shelf. Coastal lakes in southeastern Baffin Island started to accumulate sediment at this time, whereas initial lacustrine sedimentation was delayed by two millennia in the north. Reduced organic matter in lake sediment deposited during the Younger Dryas chron, and the lack of a glacial readvance at that time suggest cold summers and reduced snowfall. Ice retreated rapidly after 11 ka but was interrupted by a widespread readvance of both the LIS and local mountain glaciers ˜9.6 ka (Cockburn Substage). A second readvance occurred just before 8 ka during a period of unusually cold summers, corresponding to the 8.2 ka cold event in the Greenland Ice Sheet. Most local glaciers were behind their present margins before 7 ka, and in some instances much earlier, although the Foxe Dome of the LIS continued to slowly retract toward the present day Barnes Ice Cap throughout the Holocene. Pollen in lake sediments is rare and dominated by exotic sources prior to 12 ka. Subsequently, grass tundra became established, followed by modern tundra vegetation ca. 8 ka, with subtle changes in pollen assemblages in the late Holocene. Lake primary productivity peaked in the early Holocene, before terrestrial vegetation or marine surface waters reached their apparent thermal maxima. Lacustrine, marine, and glacial proxies all reflect significant late Holocene cooling. The onset of Neoglaciation is well dated in lacustrine records at ca. 6 ka, with intensification after 2.5 ka. The expansion of local glaciers during the Little Ice Age represents the most extensive advance since 7 ka. We suggest that the replacement of Atlantic surface

  16. Mammalian herbivores confer resilience of Arctic shrub-dominated ecosystems to changing climate.

    PubMed

    Kaarlejärvi, Elina; Hoset, Katrine S; Olofsson, Johan

    2015-09-01

    Climate change is resulting in a rapid expansion of shrubs in the Arctic. This expansion has been shown to be reinforced by positive feedbacks, and it could thus set the ecosystem on a trajectory toward an alternate, more productive regime. Herbivores, on the other hand, are known to counteract the effects of simultaneous climate warming on shrub biomass. However, little is known about the impact of herbivores on resilience of these ecosystems, that is, the capacity of a system to absorb disturbance and still remain in the same regime, retaining the same function, structure, and feedbacks. Here, we investigated how herbivores affect resilience of shrub-dominated systems to warming by studying the change of shrub biomass after a cessation of long-term experimental warming in a forest-tundra ecotone. As predicted, warming increased the biomass of shrubs, and in the absence of herbivores, shrub biomass in tundra continued to increase 4 years after cessation of the artificial warming, indicating that positive effects of warming on plant growth may persist even over a subsequent colder period. Herbivores contributed to the resilience of these systems by returning them back to the original low-biomass regime in both forest and tundra habitats. These results support the prediction that higher shrub biomass triggers positive feedbacks on soil processes and microclimate, which enable maintaining the rapid shrub growth even in colder climates. Furthermore, the results show that in our system, herbivores facilitate the resilience of shrub-dominated ecosystems to climate warming. PMID:25967156

  17. An Analysis of Arctic Climate, the Intense Arctic Cyclone of Early August 2012, and Middle to High Latitude Snowcover

    NASA Astrophysics Data System (ADS)

    Turchioe, Adam H.

    On 03 August 2012, a cyclone formed over Central Siberia and progressed northeastwards. By 0000 UTC 05 August, the cyclone reached the Arctic Ocean with a mean sea-level pressure (MSLP) of 984 hPa. Once over the Arctic Ocean, the cyclone rapidly intensified and reached a minimum pressure of 966 hPa on 06 August near 83°N and 170°W. The cyclone slowly weakened, and on 0000 UTC 10 August once again had a minimum MSLP of 984 hPa. The motivation for this presentation is driven by the likelihood that this cyclone is one of the most intense storm systems to ever impact the Arctic Ocean in the modern data era. The rarity of this storm is further supported by the fact that it occurred during the summer, prior to the climatologically favored more intense cyclone-season beginning in the fall. The purpose of this thesis will be to present the results of a climatological analysis of Arctic Ocean conditions between for 1979 to 2012. Intense cyclones to occur during this period are analyzed by frequency, trajectory, and intensity. They are categorized based on track, intensity, and seasonality. 0.5° resolution NCEP Climate Forecast Reanalysis data was the primary data source for this study. Global Forecast System FNL data was used for the cast study of the cyclone of August 2012. Changes within the climatology of snowcover extent are analyzed within this presentation, as well as a relationship between October snowcover extent and the Arctic Oscillation (AO). Suggestions will be made relating aforementioned changes in Arctic atmospheric properties and associated changes in snowcover extent. Weekly snowcover extent departures from the 25-year (1989-2013) climatology were catalogued from 1970-2014 and will be discussed.

  18. National Oceanic and Atmospheric Administration(NOAA) Arctic Climate Change Studies: A Contribution to IPY

    NASA Astrophysics Data System (ADS)

    Calder, J.; Overland, J.; Uttal, T.; Richter-Menge, J.; Rigor, I.; Crane, K.

    2004-12-01

    NOAA has initiated four activities that respond to the Arctic Climate Impact Assessment(ACIA) recommendations and represent contributions toward the IPY: 1) Arctic cloud, radiation and aerosol observatories, 2) documentation and attribution of changes in sea-ice thickness through direct measurement and modeling, 3) deriving added value from existing multivariate and historical data, and 4) following physical and biological changes in the northern Bering and Chukchi Seas. Northeast Canada, the central Arctic coast of Russia and the continuing site at Barrow have been chosen as desirable radiation/cloud locations as they exhibit different responses to Arctic Oscillation variability. NOAA is closely collaborating with Canadian groups to establish an observatory at Eureka. NOAA has begun deployment of a network of ice-tethered ice mass balance buoys complemented by several ice profiling sonars. In combination with other sea ice investigators, the Arctic buoy program, and satellites, changes can be monitored more effectively in sea ice throughout the Arctic. Retrospective data analyses includes analysis of Arctic clouds and radiation from surface and satellite measurements, correction of systematic errors in TOVS radiance data sets for the Arctic which began in 1979, addressing the feasibility of an Arctic System Reanalysis, and an Arctic Change Detection project that incorporates historical and recent physical and biological observations and news items at a website, www.arctic.noaa.gov. NOAA has begun a long-term effort to detect change in ecosystem indicators in the northern Bering and Chukchi Seas that could provide a model for other northern marine ecosystems. The first efforts were undertaken in summer 2004 during a joint Russian-US cruise that mapped the regions physical, chemical and biological parameters to set the stage for future operations over the longer term. A line of biophysical moorings provide detection of the expected warming of this area. A

  19. Climatic reconstructions in the North American arctic during the last 6000 years

    SciTech Connect

    Andrews, J.T.; Short, S.K.

    1983-07-11

    The objectives include: (1) building a data base of modern surface pollen samples from across the eastern and central Canadian arctic as well as along the North Slope of Alaska; (2) documenting changes in the pollen spectra at a series of peat and lake sites in northern Labrador, Baffin Island, and Keewatin; (3) preparing a series of transfer functions that relate modern climatic data to modern surface pollen spectra and applying the equations to fossil pollen spectra in the eastern Canadian arctic; and (4) discussing the significance of spikes of exotic tree and shrub pollen in high arctic peat and lake samples as paleoclimatic indicators.

  20. The Endangered Arctic, the Arctic as Resource Frontier: Canadian News Media Narratives of Climate Change and the North.

    PubMed

    Stoddart, Mark C J; Smith, Jillian

    2016-08-01

    The Arctic is one of the most radically altered parts of the world due to climate change, with significant social and cultural impacts as a result. Using discourse network analysis and qualitative textual analysis of articles published in the Globe and Mail and National Post during the period 2006 to 2010, we identify and analyze key frames that interpret the implications of climate change on the Arctic. We examine Canadian national news media coverage to ask: How does the Arctic enter media coverage of climate change? Is there evidence of a climate justice discourse in relation to regional disparities in the risks and harms of climate change between northern and southern Canada? Climate change in the Arctic is often framed through the lens of Canadian national interests, which downplays climate-related social impacts that are already occurring at subnational political and geographical scales. L'Arctique est une des régions du monde la plus radicalement altérée par le changement climatique, menant comme résultat des importants changements sociaux et culturels. En utilisant l'analyse des réseaux de discours ainsi que l'analyse textuelle qualitative des articles publiés dans le Globe and Mail et le National Post de 2006 à 2010, nous identifions and analysons des cadres clés qui servent à interpréter les conséquences du changement climatique dans l'Arctique. Nous examinons la couverture des médias nationaux canadiens pour pouvoir demander : comment est-ce que l'Arctique s'insère dans la couverture médiatique du changement climatique? Est-ce qu'il y a de la preuve d'un discours de la justice climatique en relation des disparités régionales des risques et méfaits du changement climatique entre le Canada du nord et du sud? Le changement climatique dans l'Arctique est souvent encadré à travers le prisme des intérêts nationaux canadiens, ce qui minimise les impacts sociaux reliés au climat qui se produisent actuellement aux échelons sous

  1. Effects of Arctic Sea Ice Decline on Weather and Climate: A Review

    NASA Astrophysics Data System (ADS)

    Vihma, Timo

    2014-09-01

    The areal extent, concentration and thickness of sea ice in the Arctic Ocean and adjacent seas have strongly decreased during the recent decades, but cold, snow-rich winters have been common over mid-latitude land areas since 2005. A review is presented on studies addressing the local and remote effects of the sea ice decline on weather and climate. It is evident that the reduction in sea ice cover has increased the heat flux from the ocean to atmosphere in autumn and early winter. This has locally increased air temperature, moisture, and cloud cover and reduced the static stability in the lower troposphere. Several studies based on observations, atmospheric reanalyses, and model experiments suggest that the sea ice decline, together with increased snow cover in Eurasia, favours circulation patterns resembling the negative phase of the North Atlantic Oscillation and Arctic Oscillation. The suggested large-scale pressure patterns include a high over Eurasia, which favours cold winters in Europe and northeastern Eurasia. A high over the western and a low over the eastern North America have also been suggested, favouring advection of Arctic air masses to North America. Mid-latitude winter weather is, however, affected by several other factors, which generate a large inter-annual variability and often mask the effects of sea ice decline. In addition, the small sample of years with a large sea ice loss makes it difficult to distinguish the effects directly attributable to sea ice conditions. Several studies suggest that, with advancing global warming, cold winters in mid-latitude continents will no longer be common during the second half of the twenty-first century. Recent studies have also suggested causal links between the sea ice decline and summer precipitation in Europe, the Mediterranean, and East Asia.

  2. Climatic anomalous patterns associated with the Arctic and Polar cell strength variations

    NASA Astrophysics Data System (ADS)

    Qian, Weihong; Wu, Kaijun; Leung, Jeremy Cheuk-Hin

    2016-03-01

    The Arctic cell as a reversed and closed loop next to the Polar cell has been recently revealed in the Northern Hemisphere (NH). In this paper, we study the interannual variability of the Arctic and Polar cell strengths during 1979-2012, and their influence on surface air temperature (SAT), precipitation, and sea-ice concentration (SIC) at mid- and high-latitudes of the NH. We show that there is a significant negative correlation between the Arctic and Polar cell strengths. Both the Arctic and Polar cell strengths can well indicate the recurring climatic anomalies of SAT, precipitation, and SIC in their extreme winters. The surface large-scale cold-warm and dry-wet anomalous patterns in these extreme winters are directly linked with the vertical structure of height and temperature anomalies in the troposphere. Results suggest that the past climatic anomalies are better indicated by the strength anomalies of the Polar and Arctic cells than the traditional indices of mid-high latitude pattern such as the Arctic Oscillation and North Atlantic Oscillation. This study illustrates a three-dimensional picture of atmospheric variable anomalies in the troposphere that result in surface climatic anomalies.

  3. Revolatilization of persistent organic pollutants in the Arctic induced by climate change

    NASA Astrophysics Data System (ADS)

    Ma, Jianmin; Hung, Hayley; Tian, Chongguo; Kallenborn, Roland

    2011-08-01

    Persistent organic pollutants (POPs) are organic compounds produced by human activities that are resistant to environmental degradation. They include industrial chemicals, such as polychlorinated biphenyls, and pesticides, such as dichlorodiphenyltrichloroethane. Owing to their persistence in the environment, POPs are transported long distances in the atmosphere, accumulating in regions such as the Arctic, where low temperatures induce their deposition. Here the compounds accumulate in wildlife and humans, putting their health at risk. The concentrations of many POPs have decreased in Arctic air over the past few decades owing to restrictions on their production and use. As the climate warms, however, POPs deposited in sinks such as water and ice are expected to revolatilize into the atmosphere, and there is evidence that this process may have already begun for volatile compounds. Here we show that many POPs, including those with lower volatilities, are being remobilized into the air from repositories in the Arctic region as a result of sea-ice retreat and rising temperatures. We analysed records of the concentrations of POPs in Arctic air since the early 1990s and compared the results with model simulations of the effect of climate change on their atmospheric abundances. Our results indicate that a wide range of POPs have been remobilized into the Arctic atmosphere over the past two decades as a result of climate change, confirming that Arctic warming could undermine global efforts to reduce environmental and human exposure to these toxic chemicals.

  4. Collaborative Research: Towards Advanced Understanding and Predictive Capability of Climate Change in the Arctic Using a High-Resolution Regional Arctic Climate Model

    SciTech Connect

    Cassano, John

    2013-06-30

    The primary research task completed for this project was the development of the Regional Arctic Climate Model (RACM). This involved coupling existing atmosphere, ocean, sea ice, and land models using the National Center for Atmospheric Research (NCAR) Community Climate System Model (CCSM) coupler (CPL7). RACM is based on the Weather Research and Forecasting (WRF) atmospheric model, the Parallel Ocean Program (POP) ocean model, the CICE sea ice model, and the Variable Infiltration Capacity (VIC) land model. A secondary research task for this project was testing and evaluation of WRF for climate-scale simulations on the large pan-Arctic model domain used in RACM. This involved identification of a preferred set of model physical parameterizations for use in our coupled RACM simulations and documenting any atmospheric biases present in RACM.

  5. Dynamics of Arctic and Sub-Arctic Climate and Atmospheric Circulation: Diagnosis of Mechanisms and Biases Using Data Assimilation

    SciTech Connect

    Eric T. DeWeaver

    2010-01-19

    This is the final report for DOE grant DE-FG02-07ER64434 to Eric DeWeaver at the University of Wisconsin-Madison. The overall goal of work performed under this grant is to enhance understanding of simulations of present-day climate and greenhouse gas-induced climate change. Enhanced understanding is desirable 1) as a prerequisite for improving simulations; 2) for assessing the credibility of model simulations and their usefulness as tools for decision support; and 3) as a means to identify robust behaviors which commonly occur over a wide range of models, and may yield insights regarding the dominant physical mechanisms which determine mean climate and produce climate change. A furthe objective is to investigate the use of data assimilation as a means for examining and correcting model biases. Our primary focus is on the Arctic, but the scope of the work was expanded to include the global climate system to the extent that research targets of opportunity present themselves. Research performed under the grant falls into five main research areas: 1) a study of data assimilation using an ensemble filter with the atmospheric circulation model of the National Center for Atmospheric Research, in which both conventional observations and observations of the refraction of radio waves from GPS satellites were used to constrain the atmospheric state of the model; 2) research on the likely future status of polar bears, in which climate model simluations were used to assess the effectiveness of climate change mitigation efforts in preserving the habitat of polar bears, now considered a threatened species under global warming; 3) as assessment of the credibility of Arctic sea ice thickness simulations from climate models; 4) An examination of the persistence and reemergence of Northern Hemisphere sea ice area anomalies in climate model simulations and in observations; 5) An examination of the roles played by changes in net radiation and surface relative humidity in determine the

  6. Variations in the Sensitivity of Shrub Growth to Climate Change along Arctic Environmental and Biotic Gradients

    NASA Astrophysics Data System (ADS)

    Beck, P. S. A.; Myers-Smith, I. H.; Elmendorf, S.; Georges, D.

    2015-12-01

    Despite evidence of rapid shrub expansion at many Arctic sites and the profound effects this has on ecosystem structure, biogeochemical cycling, and land-atmosphere feedbacks in the Arctic, the drivers of shrub growth remain poorly understood. The compilation of 41,576 annual shrub growth measurements made around the Arctic, allowed for the first systematic evaluation of the climate sensitivity of Arctic shrub growth, i.e. the strength of the relationship between annual shrub growth and monthly climate variables. The growth measurements were taken on 1821 plants of 25 species at 37 arctic and alpine sites, either as annual ring widths or as stem increments. We evaluated climate sensitivity of shrub growth for each genus-by-site combination in this data set based on the performance and parameters of linear mixed models that used CRU TS3.21 climate data as predictors of shrub growth between 1950 and 2010. 76% of genus-by-site combinations showed climate sensitive growth, but climate-growth relationships varied with soil moisture, species canopy height, and geographic position within the species ranges. Shrubs growing at sites with more soil moisture showed greater climate sensitivity, suggesting that water availability might limit shrub growth if continued warming isn't matched by a steady increase in soil moisture. Tall shrub species growing at their northern range limit were particularly climate sensitive causing climate sensitivity of shrubs to peak at the transition between Low and High Arctic, where carbon storage in permafrost is greatest. Local and regional studies have documented matching spatial and temporal patterns in dendrochronological measurements and satellite observations of vegetation indices both in boreal and Arctic regions. Yet the circumarctic comparison of patterns in dendrochronological and remote sensing data sets yielded poor levels of agreement. In much of the Arctic, steep environmental gradients generate fine spatial patterns of vegetation

  7. Species interactions and response time to climate change: ice-cover and terrestrial run-off shaping Arctic char and brown trout competitive asymmetries

    NASA Astrophysics Data System (ADS)

    Finstad, A. G.; Palm Helland, I.; Jonsson, B.; Forseth, T.; Foldvik, A.; Hessen, D. O.; Hendrichsen, D. K.; Berg, O. K.; Ulvan, E.; Ugedal, O.

    2011-12-01

    There has been a growing recognition that single species responses to climate change often mainly are driven by interaction with other organisms and single species studies therefore not are sufficient to recognize and project ecological climate change impacts. Here, we study how performance, relative abundance and the distribution of two common Arctic and sub-Arctic freshwater fishes (brown trout and Arctic char) are driven by competitive interactions. The interactions are modified both by direct climatic effects on temperature and ice-cover, and indirectly through climate forcing of terrestrial vegetation pattern and associated carbon and nutrient run-off. We first use laboratory studies to show that Arctic char, which is the world's most northernmost distributed freshwater fish, outperform trout under low light levels and also have comparable higher growth efficiency. Corresponding to this, a combination of time series and time-for-space analyses show that ice-cover duration and carbon and nutrient load mediated by catchment vegetation properties strongly affected the outcome of the competition and likely drive the species distribution pattern through competitive exclusion. In brief, while shorter ice-cover period and decreased carbon load favored brown trout, increased ice-cover period and increased carbon load favored Arctic char. Length of ice-covered period and export of allochthonous material from catchments are major, but contrasting, climatic drivers of competitive interaction between these two freshwater lake top-predators. While projected climate change lead to decreased ice-cover, corresponding increase in forest and shrub cover amplify carbon and nutrient run-off. Although a likely outcome of future Arctic and sub-arctic climate scenarios are retractions of the Arctic char distribution area caused by competitive exclusion, the main drivers will act on different time scales. While ice-cover will change instantaneously with increasing temperature

  8. Response of Arctic temperature to changes in emissions of short-lived climate forcers

    NASA Astrophysics Data System (ADS)

    Sand, M.; Berntsen, T. K.; von Salzen, K.; Flanner, M. G.; Langner, J.; Victor, D. G.

    2016-03-01

    There is growing scientific and political interest in the impacts of climate change and anthropogenic emissions on the Arctic. Over recent decades temperatures in the Arctic have increased at twice the global rate, largely as a result of ice-albedo and temperature feedbacks. Although deep cuts in global CO2 emissions are required to slow this warming, there is also growing interest in the potential for reducing short-lived climate forcers (SLCFs; refs ,). Politically, action on SLCFs may be particularly promising because the benefits of mitigation are seen more quickly than for mitigation of CO2 and there are large co-benefits in terms of improved air quality. This Letter is one of the first to systematically quantify the Arctic climate impact of regional SLCFs emissions, taking into account black carbon (BC), sulphur dioxide (SO2), nitrogen oxides (NOx), volatile organic compounds (VOCs), organic carbon (OC) and tropospheric ozone (O3), and their transport processes and transformations in the atmosphere. This study extends the scope of previous works by including more detailed calculations of Arctic radiative forcing and quantifying the Arctic temperature response. We find that the largest Arctic warming source is from emissions within the Asian nations owing to the large absolute amount of emissions. However, the Arctic is most sensitive, per unit mass emitted, to SLCFs emissions from a small number of activities within the Arctic nations themselves. A stringent, but technically feasible mitigation scenario for SLCFs, phased in from 2015 to 2030, could cut warming by 0.2 (+/-0.17) K in 2050.

  9. Arctic sea ice and climate change--will the ice disappear in this century?

    PubMed

    Johannessen, O M; Miles, M W

    2000-01-01

    A consensus among climate change prediction scenarios using coupled ocean-climate general circulation models (GCMs) is enhanced warming in the Arctic. This suggests that changes in the Arctic sea ice cover may provide early indications of global warming. Observational evidence of substantial changes in the ice cover has been found recently using data from satellites and submarines. Satellite-borne microwave sensor data analyses have established a 3% per decade decrease in the spatial extent of the Arctic ice cover in the past 20 years. Moreover, a 7% per decade decrease in thicker, multi-year (perennial) ice pack has been revealed. This apparent transformation is corroborated by independent data that indicate substantial decreases in the average ice thickness from 3.1 to 1.8 m from the 1950s/1970s to the mid 1990s, averaging about 4 cm per year. It remains uncertain whether these observed changes are manifestations of global warming or are the result of anomalous atmospheric circulation--or both. However, if the recent trends continue, the Arctic sea ice cover could disappear this century, at least in summer, with important consequences for the regional and global ocean-climate system. This article synthesizes recent variability and trends in Arctic sea ice in the perspective of global climate change, and discusses their potential ramifications. PMID:11077477

  10. Multi-proxy evidence for climate-driven changes in arctic lakes from northern Russia over the Holocene.

    NASA Astrophysics Data System (ADS)

    Self, Angela; Brooks, Stephen; Jones, Vivienne; Solovieva, Nadia; McGowan, Suzanne; Rosén, Peter; Parrott, Emily; Seppä, Heikki; Salonen, Sakari

    2010-05-01

    Average arctic temperatures have increased at almost twice the rate of the rest of the world over the last 100 years and climate projections suggest this trend is likely to continue resulting in an additional warming of 2 - 3°C in annual mean air temperatures by 2050. Freshwater ecosystems occupy a substantial area of the terrestrial environment in the Arctic and are particularly sensitive to temperature increases which may lead to profound changes in catchment characteristics, permafrost, hydrology and nutrient availability. Therefore it is important to understand how past changes in climate have affected these ecosystems. In this paper we present one of the first quantitative multi-proxy climate records from arctic Siberia. The affect of early - mid Holocene and recent climate change on arctic lakes in northern Russia were investigated in multi-proxy studies. The past climate was reconstructed using chironomid inference models to estimate mean July air temperatures and trends in continentality. Stable isotopes and LOI were analysed to infer past changes in sediment organic matter. Near-infrared spectroscopy (NIRS) and/or diatoms were used to infer changes in lake water total organic carbon and algal pigments and/or diatoms were used to infer changes in productivity and light penetration in the lake. Analyses of a sediment core from a tundra lake (Lake Kharinei) in north-eastern European Russia show significant assemblage changes in diatoms, chironomids and pigments, which coincide with climate-driven vegetation shifts from open birch forest to spruce forest and then to tundra over the Holocene. During the open birch phase of the late Glacial - early Holocene, chironomid-inferred reconstructions suggest that the climate was approximately 1 - 3°C warmer and more continental than present. Isotopic analyses indicate a productive environment receiving a significant input of organic material from terrestrial plants into the lake. Both diatoms and NIRS-TOC also

  11. The Arctic freshwater cycle during a naturally and an anthropogenically induced warm climate

    NASA Astrophysics Data System (ADS)

    Davies, Frazer J.; Renssen, Hans; Goosse, Hugues

    2014-04-01

    The Arctic freshwater cycle plays an important role in regulating regional and global climate. Current observations suggest that an intensification of the high-northern latitude hydrological cycle has caused a freshening of the Arctic and sub-Arctic seas, increasing the potential of weakening overturning strength in the Nordic seas, and reducing temperatures. It is not known if this freshening is a manifestation of the current anthropogenic warming and if the Arctic freshwater cycle has exhibited similar changes in the past, in particular as a response to naturally induced periods of warming, for example during the mid-Holocene hypsithermal. Thus, we have used an earth model of intermediate complexity, LOVECLIM, to investigate the response of the Arctic freshwater cycle, during two warm periods that evolved under different sets of forcings, the mid-Holocene and the twenty-first century. A combination of proxy reconstructions and modelling studies have shown these two periods to exhibit similar surface temperature anomalies, compared to the pre-industrial period, however, it has yet to be determined if the Arctic freshwater cycle and thus, the transport and redistribution of freshwater to the Arctic and the sub-Arctic seas, during these two warm periods, is comparable. Here we provide an overview that shows that the response of the Arctic freshwater cycle during the first half of the twenty-first century can be interpreted as an `extreme' mid-Holocene hydrological cycle. Whilst for the remainder of the twenty-first century, the Arctic freshwater cycle and the majority of its components will likely transition into what can only be described as truly anthropogenic in nature.

  12. The role of snow cover and soil freeze/thaw cycles affecting boreal-arctic soil carbon dynamics

    NASA Astrophysics Data System (ADS)

    Yi, Y.; Kimball, J. S.; Rawlins, M. A.; Moghaddam, M.; Euskirchen, E. S.

    2015-07-01

    Northern Hemisphere permafrost affected land areas contain about twice as much carbon as the global atmosphere. This vast carbon pool is vulnerable to accelerated losses through mobilization and decomposition under projected global warming. Satellite data records spanning the past 3 decades indicate widespread reductions (∼ 0.8-1.3 days decade-1) in the mean annual snow cover extent and frozen season duration across the pan-Arctic domain, coincident with regional climate warming trends. How the soil carbon pool responds to these changes will have a large impact on regional and global climate. Here, we developed a coupled terrestrial carbon and hydrology model framework with detailed 1-D soil heat transfer representation to investigate the sensitivity of soil organic carbon stocks and soil decomposition to changes in snow cover and soil freeze/thaw processes in the Pan-Arctic region over the past three decades (1982-2010). Our results indicate widespread soil active layer deepening across the pan-Arctic, with a mean decadal trend of 6.6 ± 12.0 (SD) cm, corresponding with widespread warming and lengthening non-frozen season. Warming promotes vegetation growth and soil heterotrophic respiration, particularly within surface soil layers (≤ 0.2 m). The model simulations also show that seasonal snow cover has a large impact on soil temperatures, whereby increases in snow cover promote deeper (≥ 0.5 m) soil layer warming and soil respiration, while inhibiting soil decomposition from surface (≤ 0.2 m) soil layers, especially in colder climate zones (mean annual T ≤ -10 °C). Our results demonstrate the important control of snow cover in affecting northern soil freeze/thaw and soil carbon decomposition processes, and the necessity of considering both warming, and changing precipitation and snow cover regimes in characterizing permafrost soil carbon dynamics.

  13. Influence of Arctic Sea Ice Extent on Polar Cloud Fraction and Vertical Structure and Implications for Regional Climate

    NASA Technical Reports Server (NTRS)

    Palm, Stephen P.; Strey, Sara T.; Spinhirne, James; Markus, Thorsten

    2010-01-01

    Recent satellite lidar measurements of cloud properties spanning a period of 5 years are used to examine a possible connection between Arctic sea ice amount and polar cloud fraction and vertical distribution. We find an anticorrelation between sea ice extent and cloud fraction with maximum cloudiness occurring over areas with little or no sea ice. We also find that over ice!free regions, there is greater low cloud frequency and average optical depth. Most of the optical depth increase is due to the presence of geometrically thicker clouds over water. In addition, our analysis indicates that over the last 5 years, October and March average polar cloud fraction has increased by about 7% and 10%, respectively, as year average sea ice extent has decreased by 5% 7%. The observed cloud changes are likely due to a number of effects including, but not limited to, the observed decrease in sea ice extent and thickness. Increasing cloud amount and changes in vertical distribution and optical properties have the potential to affect the radiative balance of the Arctic region by decreasing both the upwelling terrestrial longwave radiation and the downward shortwave solar radiation. Because longwave radiation dominates in the long polar winter, the overall effect of increasing low cloud cover is likely a warming of the Arctic and thus a positive climate feedback, possibly accelerating the melting of Arctic sea ice.

  14. The Influence of Arctic Sea Ice Extent on Polar Cloud Fraction and Vertical Structure and Implications for Regional Climate

    NASA Technical Reports Server (NTRS)

    Palm, Stephen P.; Strey, Sara T.; Spinhirne, James; Markus, Thorsten

    2010-01-01

    Recent satellite lidar measurements of cloud properties spanning a period of five years are used to examine a possible connection between Arctic sea ice amount and polar cloud fraction and vertical distribution. We find an anti-correlation between sea ice extent and cloud fraction with maximum cloudiness occurring over areas with little or no sea ice. We also find that over ice free regions, there is greater low cloud frequency and average optical depth. Most of the optical depth increase is due to the presence of geometrically thicker clouds over water. In addition, our analysis indicates that over the last 5 years, October and March average polar cloud fraction has increased by about 7 and 10 percent, respectively, as year average sea ice extent has decreased by 5 to 7 percent. The observed cloud changes are likely due to a number of effects including, but not limited to, the observed decrease in sea ice extent and thickness. Increasing cloud amount and changes in vertical distribution and optical properties have the potential to affect the radiative balance of the Arctic region by decreasing both the upwelling terrestrial longwave radiation and the downward shortwave solar radiation. Since longwave radiation dominates in the long polar winter, the overall effect of increasing low cloud cover is likely a warming of the Arctic and thus a positive climate feedback, possibly accelerating the melting of Arctic sea ice.

  15. Climate driven changes in hydrology, nutrient cycling, and food web dynamics in surface waters of the Arctic Coastal Plain, Alaska

    NASA Astrophysics Data System (ADS)

    Koch, J. C.; Wipfli, M.; Schmutz, J.; Gurney, K.

    2011-12-01

    Arctic ecosystems are changing rapidly as a result of a warming climate. While many areas of the arctic are expected to dry as a result of warming, the Arctic Coastal Plain (ACP) of Alaska, which extends from the Brooks Range north to the Beaufort Sea will likely become wetter, because subsurface hydrologic fluxes are constrained by thick, continuous permafrost. This landscape is characterized by large, oriented lakes and many smaller ponds that form in the low centers and troughs/edges of frost polygons. This region provides important breeding habitat for many migratory birds including loons, arctic terns, eiders, shorebirds, and white-fronted geese, among others. Increased hydrologic fluxes may provide a bottom-up control on the success of these species by altering the availability of food resources including invertebrates and fish. This work aimed to 1) characterize surface water fluxes and nutrient availability in the small streams and lake types of two study regions in the ACP, 2) predict how increased hydrological fluxes will affect the lakes, streams, and water chemistry, and 3) use nutrient additions to simulate likely changes in lake chemistry and invertebrate availability. Initial observations suggest that increasing wetland areas and availability of nutrients will result in increased invertebrate abundance, while the potential for drainage and terrestrialization of larger lakes may reduce fish abundance and overwintering habitat. These changes will likely have positive implications for insectivores and negative implications for piscivorous waterfowl.

  16. Climate change impacts on environmental and human exposure to mercury in the arctic.

    PubMed

    Sundseth, Kyrre; Pacyna, Jozef M; Banel, Anna; Pacyna, Elisabeth G; Rautio, Arja

    2015-04-01

    This paper reviews information from the literature and the EU ArcRisk project to assess whether climate change results in an increase or decrease in exposure to mercury (Hg) in the Arctic, and if this in turn will impact the risks related to its harmful effects. It presents the state-of-the art of knowledge on atmospheric mercury emissions from anthropogenic sources worldwide, the long-range transport to the Arctic, and it discusses the likely environmental fate and exposure effects on population groups in the Arctic under climate change conditions. The paper also includes information about the likely synergy effects (co-benefits) current and new climate change polices and mitigation options might have on mercury emissions reductions in the future. The review concludes that reductions of mercury emission from anthropogenic sources worldwide would need to be introduced as soon as possible in order to assure lowering the adverse impact of climate change on human health. Scientific information currently available, however, is not in the position to clearly answer whether climate change will increase or decrease the risk of exposure to mercury in the Arctic. New research should therefore be undertaken to model the relationships between climate change and mercury exposure. PMID:25837201

  17. Climate Change Impacts on Environmental and Human Exposure to Mercury in the Arctic

    PubMed Central

    Sundseth, Kyrre; Pacyna, Jozef M.; Banel, Anna; Pacyna, Elisabeth G.; Rautio, Arja

    2015-01-01

    This paper reviews information from the literature and the EU ArcRisk project to assess whether climate change results in an increase or decrease in exposure to mercury (Hg) in the Arctic, and if this in turn will impact the risks related to its harmful effects. It presents the state-of-the art of knowledge on atmospheric mercury emissions from anthropogenic sources worldwide, the long-range transport to the Arctic, and it discusses the likely environmental fate and exposure effects on population groups in the Arctic under climate change conditions. The paper also includes information about the likely synergy effects (co-benefits) current and new climate change polices and mitigation options might have on mercury emissions reductions in the future. The review concludes that reductions of mercury emission from anthropogenic sources worldwide would need to be introduced as soon as possible in order to assure lowering the adverse impact of climate change on human health. Scientific information currently available, however, is not in the position to clearly answer whether climate change will increase or decrease the risk of exposure to mercury in the Arctic. New research should therefore be undertaken to model the relationships between climate change and mercury exposure. PMID:25837201

  18. Is "Warm Arctic, Cold Continent" A Fingerprint Pattern of Climate Change?

    NASA Astrophysics Data System (ADS)

    Hoerling, M. P.; Sun, L.; Perlwitz, J.

    2015-12-01

    Cold winters and cold waves have recently occurred in Europe, central Asia and the Midwest to eastern United States, even as global mean temperatures set record highs and Arctic amplification of surface warming continued. Since 1979, Central Asia winter temperatures have in fact declined. Conjecture has it that more cold extremes over the mid-latitude continents should occur due to global warming and the impacts of Arctic sea ice loss. A Northern Hemisphere temperature signal termed the "Warm Arctic, Cold Continent" pattern has thus been surmised. Here we use a multi-model approach to test the hypothesis that such a pattern is indeed symptomatic of climate change. Diagnosis of a large model ensemble of historical climate simulations shows some individual realizations to yield cooling trends over Central Asia, but importantly the vast majority show warming. The observed cooling has thus likely been a low probability state of internal variability, not a fingerprint of forced climate change. We show that daily temperature variations over continents decline in winter due to global warming, and cold waves become less likely. This is partly related to diminution of Arctic cold air reservoirs due to warming-induced sea ice loss. Nonetheless, we find some evidence and present a physical basis that Arctic sea ice loss alone can induce a winter cooling over Central Asia, though with a magnitude that is appreciably smaller than the overall radiative-forced warming signal. Our results support the argument that recent cooling trends over central Asia, and cold extreme events over the winter continents, have principally resulted from atmospheric internal variability and have been neither a forced response to Arctic seas ice loss nor a symptom of global warming. The paradigm of climate change is thus better expressed as "Warm Arctic, Warm Continent" for the NH winter.

  19. Interannual climate variations in Arctic as driven by the Global atmosphere oscillation

    NASA Astrophysics Data System (ADS)

    Serykh, Ilya; Byshev, Vladimir; Neiman, Victor; Sidorova, Alexandra; Sonechkin, Dmitry

    2015-04-01

    The present-day global climate change affects the Arctic basin substantially more because of the sea ice cover extinction and the permafrost melting. But there are essential variations of these effects from year to year. We believe that these variations might be a regional manifestation of a planetary-scale phenomenon named the Global atmospheric oscillation (GAO). GAO includes the well-known El Niño - Southern Oscillation (ENSO) process and similar processes in equatorial Atlantic and Indian Oceans within itself. The goal of this report is to present some arguments to support this point of view. For this goal, we have studied some interrelations between the above-mentioned Arctic anomalies and GAO as seen in global re-analyses of the sea level pressure (SLP) and near surface temperature (NST) for the period of 1920-2013. The mean global fields of SLP and NST have been computed for all El Niño events falling into this time period, and separately, for all and La Niña events. As a result, two (for SLP and NST as well) global fields of the mean El Niño/La Niña difference were obtained. Statistical significance of the non-zero values of these fields, i.e. the reality of GAO, was evaluated with the t-Student's test. It turned out that the main spatial structures of GAO, presented specifically by El Niño and La Niña events in Pacific region, exist at a very high level (up to 99%, t>4) of the significance. Therefore, one can conclude that the interannual-scale dynamics of GAO is actually reflected in the climate features of different regions of the Earth, including the Russian Arctic. In particular, when the boreal winter season coincides with an El Niño event GAO is indicative by a negative anomaly of NST (about -1°C) and a positive anomaly of SLP over the Arctic basin. In contrary, significant (about +1°C) positive anomaly of NST along with reduced SLP over the whole Arctic region is typical for any La Niña event (up to 95%, t>2). To control the reliability

  20. Increasing shrub abundance and N addition in Arctic tundra affect leaf and root litter decomposition differently

    NASA Astrophysics Data System (ADS)

    McLaren, J.; van de Weg, M. J.; Shaver, G. R.; Gough, L.

    2013-12-01

    Changes in global climate have resulted in a ';greening' of the Arctic as the abundance of deciduous shrub species increases. Consequently, not only the living plant community, but also the litter composition changes, which in turn can affect carbon turnover patterns in the Arctic. We examined effects of changing litter composition (both root and leaf litter) on decomposition rates with a litter bag study, and specifically focused on the impact of deciduous shrub Betula nana litter on litter decomposition from two evergreen shrubs (Ledum palustre, and Vaccinium vitis-idaea) and one graminoid (Eriophorum vaginatum) species. Additionally, we investigated how decomposition was affected by nutrient availability by placing the litterbags in an ambient and a fertilized moist acidic tundra environment. Measurements were carried out seasonally over 2 years (after snow melt, mid-growing season, end growing season). We measured litter mass loss over time, as well as the respiration rates (standardized for temperature and moisture) and temperature sensitivity of litter respiration at the time of harvesting the litter bags. For leaves, Betula litter decomposed faster than the other three species, with Eriophorum leaves decomposing the slowest. This pattern was observed for both mass loss and litter respiration rates, although the differences in respiration became smaller over time. Surprisingly, combining Betula with any other species resulted in slower overall weight loss rates than would be predicted based on monoculture weight loss rates. This contrasted with litter respiration at the time of sampling, which showed a positive mixing effect of adding Betula leaf liter to the other species. Apparently, during the first winter months (September - May) Betula litter decomposition is negatively affected by mixing the species and this legacy can still be observed in the total mass loss results later in the year. For root litter there were fewer effects of species identity on root

  1. Arctic climate response to the termination of the African Humid Period

    NASA Astrophysics Data System (ADS)

    Muschitiello, Francesco; Zhang, Qiong; Sundqvist, Hanna S.; Davies, Frazer J.; Renssen, Hans

    2015-10-01

    The Earth's climate response to the rapid vegetation collapse at the termination of the African Humid Period (AHP) (5.5-5.0 kyr BP) is still lacking a comprehensive investigation. Here we discuss the sensitivity of mid-Holocene Arctic climate to changes in albedo brought by a rapid desertification of the Sahara. By comparing a network of surface temperature reconstructions with output from a coupled global climate model, we find that, through a system of land-atmosphere feedbacks, the end of the AHP reduced the atmospheric and oceanic poleward heat transport from tropical to high northern latitudes. This entails a general weakening of the mid-latitude Westerlies, which results in a shift towards cooling over the Arctic and North Atlantic regions, and a change from positive to negative Arctic Oscillation-like conditions. This mechanism would explain the sign of rapid hydro-climatic perturbations recorded in several reconstructions from high northern latitudes at 5.5-5.0 kyr BP, suggesting that these regions are sensitive to changes in Saharan land cover during the present interglacial. This is central in the debate surrounding Arctic climate amplification and future projections for subtropical precipitation changes.

  2. Assessing climate impacts and risks of ocean albedo modification in the Arctic

    NASA Astrophysics Data System (ADS)

    Mengis, N.; Martin, T.; Keller, D. P.; Oschlies, A.

    2016-05-01

    The ice albedo feedback is one of the key factors of accelerated temperature increase in the high northern latitudes under global warming. This study assesses climate impacts and risks of idealized Arctic Ocean albedo modification (AOAM), a proposed climate engineering method, during transient climate change simulations with varying representative concentration pathway (RCP) scenarios. We find no potential for reversing trends in all assessed Arctic climate metrics under increasing atmospheric CO2 concentrations. AOAM only yields an initial offset during the first years after implementation. Nevertheless, sea ice loss can be delayed by 25(60) years in the RCP8.5(RCP4.5) scenario and the delayed thawing of permafrost soils in the AOAM simulations prevents up to 40(32) Pg of carbon from being released by 2100. AOAM initially dampens the decline of the Atlantic Meridional Overturning and delays the onset of open ocean deep convection in the Nordic Seas under the RCP scenarios. Both these processes cause a subsurface warming signal in the AOAM simulations relative to the default RCP simulations with the potential to destabilize Arctic marine gas hydrates. Furthermore, in 2100, the RCP8.5 AOAM simulation diverts more from the 2005-2015 reference state in many climate metrics than the RCP4.5 simulation without AOAM. Considering the demonstrated risks, we conclude that concerning longer time scales, reductions in emissions remain the safest and most effective way to prevent severe changes in the Arctic.

  3. The Arctic Oscillation, climate change and the effects on precipitation in Israel

    NASA Astrophysics Data System (ADS)

    Givati, Amir; Rosenfeld, Daniel

    2013-10-01

    The Arctic Oscillation (AO) has been found in previous studies to be a major synoptic factor affecting the climate of many regions in the high and mid-latitudes. This paper demonstrates the physical process by which the AO affects the climate of the Eastern Mediterranean basin, with a focus on precipitation in Israel as a case study. It is shown that a trend of increasing AO is associated with a substantial decrease of winter precipitation from the Iberian Peninsula, though Italy, Greece, Turkey and Cyprus, as well as Lebanon, Syria and also the northern parts of Israel. Winter rain is slightly increased in the southern coast of the eastern half of the Mediterranean Sea. The immediate meteorological causes are shown to be a larger northerly component of the flow over the Mediterranean Sea, associated with a decreasing relative humidity and stability, except over the southern coast, where the air mass has the longest track over the relatively warm water. We suggest here that the observed changes in air flow that drives the precipitation trends can be explained by shifts in the AO that can be partially explained by increasing greenhouses gases. Results from the IPCC multi climate models show that the AO will continue to increase during the 21st century. This increase may lead to a continuation of the trends discussed here. The importance of the analysis provided here is in pointing out the possibility that processes that have been predicted by global warming and changes in global circulation have already started to affect precipitation and major water resources in the Mediterranean basin.

  4. A new climate era in the sub-Arctic: Accelerating climate changes and multiple impacts

    NASA Astrophysics Data System (ADS)

    Callaghan, Terry V.; Bergholm, Fredrik; Christensen, Torben R.; Jonasson, Christer; Kokfelt, Ulla; Johansson, Margareta

    2010-07-01

    Climate warming in the Swedish sub-Arctic since 2000 has reached a level at which statistical analysis shows for the first time that current warming has exceeded that in the late 1930's and early 1940's, and has significantly crossed the 0°C mean annual temperature threshold which causes many cryospheric and ecological impacts. The accelerating temperature increase trend has driven similar trends in the century-long increase in snow thickness, loss of lake ice, increases in active layer thickness, lake water TOC (total organic carbon) concentrations and the assemblages of diatoms, and changes in tree-line location and plant community structure. Some of these impacts were not evident in the first warm period of the 20th Century. Changes in climate are associated with reduced temperature variability, particularly loss of cold winters and cool summers, and an increase in extreme precipitation events that cause mountain slope instability and infrastructure failure. The long term records of multiple, local environmental factors compiled here for the first time provide detailed information for adaptation strategy development while dramatic changes in an environment particularly vulnerable to climate change highlight the need to adopt global mitigation strategies.

  5. Response of Arctic Temperature to Changes in Emissions of Short-Lived Climate Forcers

    NASA Astrophysics Data System (ADS)

    Sand, M.; Berntsen, T.; von Salzen, K.; Flanner, M.; Langner, J.; Victor, D. G.

    2014-12-01

    There is growing scientific and political interest in the impacts of climate change and anthropogenic emissions on the Arctic. Over recent decades temperatures in the Arctic have increased twice the global rate, largely due to ice albedo and temperature feedbacks. While deep cuts in global CO2 emissions are required to slow this warming, there is also growing interest in the potential for reducing short lived climate forcers (SLCFs). Politically, action on SLCFs may be particularly promising because the benefits of mitigation appear promptly and there are large co-benefits in terms of improved air quality. This study is the first to systematically quantify the Arctic climate impact of regional SLCF emissions, taking into account BC, sulphur dioxide (SO2), nitrogen oxides (NOx), volatile hydrocarbons (VOC), organic carbon (OC) and tropospheric ozone, their transport processes and transformations in the atmosphere. Using several chemical transport models we perform detailed radiative forcing calculations from emissions of these species. Geographically we separate emissions into seven source regions that correspond with the national groupings of the Arctic Council, the leading body organizing international policy in the region (the United States, Canada, the Nordic countries, the rest of Europe, Russia, East and South Asia, and the rest of the world). We look at six main sectors known to account for [nearly all] of these emissions: households (domestic), energy/industry/waste, transport, agricultural fires, grass/forest fires, and gas flaring. We find that the largest Arctic warming source is from emissions within the Asian nations. However, the Arctic is most sensitive, per unit mass emitted, to SLCFs emissions from a small number of activities within the Arctic nations themselves. A stringent, but technically feasible SLCFs mitigation scenario, phased in from 2015 through 2030, can cut warming by 0.2 K in 2050.

  6. Response of Arctic Temperature to Changes in Emissions of Short-Lived Climate Forcers

    NASA Astrophysics Data System (ADS)

    Sand, M.; Berntsen, T.; von Salzen, K.; Flanner, M.; Langner, J.; Victor, D. G.

    2015-12-01

    There is growing scientific and political interest in the impacts of climate change and anthropogenic emissions on the Arctic. Over recent decades temperatures in the Arctic have increased twice the global rate, largely due to ice albedo and temperature feedbacks. While deep cuts in global CO2 emissions are required to slow this warming, there is also growing interest in the potential for reducing short lived climate forcers (SLCFs). Politically, action on SLCFs may be particularly promising because the benefits of mitigation appear promptly and there are large co-benefits in terms of improved air quality. This study is the first to systematically quantify the Arctic climate impact of regional SLCF emissions, taking into account BC, sulphur dioxide (SO2), nitrogen oxides (NOx), volatile hydrocarbons (VOC), organic carbon (OC) and tropospheric ozone, their transport processes and transformations in the atmosphere. Using several chemical transport models we perform detailed radiative forcing calculations from emissions of these species. Geographically we separate emissions into seven source regions that correspond with the national groupings of the Arctic Council, the leading body organizing international policy in the region (the United States, Canada, the Nordic countries, the rest of Europe, Russia, East and South Asia, and the rest of the world). We look at six main sectors known to account for [nearly all] of these emissions: households (domestic), energy/industry/waste, transport, agricultural fires, grass/forest fires, and gas flaring. We find that the largest Arctic warming source is from emissions within the Asian nations. However, the Arctic is most sensitive, per unit mass emitted, to SLCFs emissions from a small number of activities within the Arctic nations themselves. A stringent, but technically feasible SLCFs mitigation scenario, phased in from 2015 through 2030, can cut warming by 0.2 K in 2050.

  7. Benzothiadiazole affects the leaf proteome in arctic bramble (Rubus arcticus).

    PubMed

    Hukkanen, Anne; Kokko, Harri; Buchala, Antony; Häyrinen, Jukka; Kärenlampi, Sirpa

    2008-11-01

    Benzothiadiazole (BTH) induces resistance to the downy mildew pathogen, Peronospora sparsa, in arctic bramble, but the basis for the BTH-induced resistance is unknown. Arctic bramble cv. Mespi was treated with BTH to study the changes in leaf proteome and to identify proteins with a putative role in disease resistance. First, BTH induced strong expression of one PR-1 protein isoform, which was also induced by salicylic acid (SA). The PR-1 was responsive to BTH and exogenous SA despite a high endogenous SA content (20-25 microg/g fresh weight), which increased to an even higher level after treatment with BTH. Secondly, a total of 792 protein spots were detected in two-dimensional gel electrophoresis, eight proteins being detected solely in the BTH-treated plants. BTH caused up- or down-regulation of 72 and 31 proteins, respectively, of which 18 were tentatively identified by mass spectrometry. The up-regulation of flavanone-3-hydroxylase, alanine aminotransferase, 1-aminocyclopropane-1-carboxylate oxidase, PR-1 and PR-10 proteins may partly explain the BTH-induced resistance against P. sparsa. Other proteins with changes in intensity appear to be involved in, for example, energy metabolism and protein processing. The decline in ATP synthase, triosephosphate isomerase, fructose bisphosphate aldolase and glutamine synthetase suggests that BTH causes significant changes in primary metabolism, which provides one possible explanation for the decreased vegetative growth of foliage and rhizome observed in BTH-treated plants. PMID:19019008

  8. How Spatial Variation in Areal Extent and Configuration of Labile Vegetation States Affect the Riparian Bird Community in Arctic Tundra

    PubMed Central

    Henden, John-André; Yoccoz, Nigel G.; Ims, Rolf A.; Langeland, Knut

    2013-01-01

    The Arctic tundra is currently experiencing an unprecedented combination of climate change, change in grazing pressure by large herbivores and growing human activity. Thickets of tall shrubs represent a conspicuous vegetation state in northern and temperate ecosystems, where it serves important ecological functions, including habitat for wildlife. Thickets are however labile, as tall shrubs respond rapidly to both abiotic and biotic environmental drivers. Our aim was to assess how large-scale spatial variation in willow thicket areal extent, configuration and habitat structure affected bird abundance, occupancy rates and species richness so as to provide an empirical basis for predicting the outcome of environmental change for riparian tundra bird communities. Based on a 4-year count data series, obtained through a large-scale study design in low arctic tundra in northern Norway, statistical hierarchical community models were deployed to assess relations between habitat configuration and bird species occupancy and community richness. We found that species abundance, occupancy and richness were greatly affected by willow areal extent and configuration, habitat features likely to be affected by intense ungulate browsing as well as climate warming. In sum, total species richness was maximized in large and tall willow patches of small to intermediate degree of fragmentation. These community effects were mainly driven by responses in the occupancy rates of species depending on tall willows for foraging and breeding, while species favouring other vegetation states were not affected. In light of the predicted climate driven willow shrub encroachment in riparian tundra habitats, our study predicts that many bird species would increase in abundance, and that the bird community as a whole could become enriched. Conversely, in tundra regions where overabundance of large herbivores leads to decreased areal extent, reduced height and increased fragmentation of willow thickets

  9. Arctic Clouds

    Atmospheric Science Data Center

    2013-04-19

    ...     View Larger Image Stratus clouds are common in the Arctic during the summer months, and are ... formats available at JPL August 23, 2000 - Stratus clouds help modulate the arctic climate. project:  ...

  10. Impacts of Arctic Climate Change on Tundra Fire Regimes at Interannual to Millennial Timescales

    NASA Astrophysics Data System (ADS)

    Hu, F.; Young, A. M.; Chipman, M. L.; Duffy, P.; Higuera, P. E.

    2014-12-01

    Tundra burning is emerging as a key process in the rapidly changing Arctic, and knowledge of tundra fire-regime responses to climate change is essential for projecting Earth system dynamics. This presentation will focus on climate-fire relationships in the Arctic, spatiotemporal patterns of Holocene tundra burning, and the effects of tundra burning on carbon cycling. Analysis of historical records reveals that across the Arctic, tundra burning occurred primarily in areas where mean summer temperature exceeded 9 °C and total summer precipitation was below 115 mm. In Alaska, summer temperature and precipitation explain >90% of the interannual variability in tundra area burned from AD 1950-2009, with thresholds of 10.5 °C and 140 mm. These patterns imply tipping points in tundra fire-regime responses to climate change. The frequency of tundra fires has varied greatly across space and through time. Approximately 1.0% of the circum-Arctic tundra burned from AD 2002-2013, and 4.5% of the Alaskan tundra burned from AD 1950-2009. The latter encompassed ecoregions with fire rotation periods ranging from ~400 to 13,640 years. Charcoal analysis of lake sediments also shows that Arctic tundra can sustain a wide range of fire regimes. Fires were rare on the Alaskan North Slope throughout the Holocene, implying that the climate thresholds evident in the historical records have seldom been crossed. In contrast, in areas of NW Alaska, tundra has burned regularly at 100-250 year intervals during the late Holocene. Tundra burning may cause sudden releases of the enormous amount of Arctic soil C. Charcoal particles from recent burns yielded 14C ages of AD 1952-2006. Thus the C consumed in recent fires may recover through vegetation succession. However, our results suggest that in areas that have burned multiple times in recent decades, old soil C is vulnerable to future fires.

  11. Does Change in the Arctic Sea Ice Indicate Climate Change? A Lesson Using Geospatial Technology

    ERIC Educational Resources Information Center

    Bock, Judith K.

    2011-01-01

    The Arctic sea ice has not since melted to the 2007 extent, but annual summer melt extents do continue to be less than the decadal average. Climate fluctuations are well documented by geologic records. Averages are usually based on a minimum of 10 years of averaged data. It is typical for fluctuations to occur from year to year and season to…

  12. Key Findings of the AMAP 2015 Assessment on Black Carbon and Tropospheric Ozone as Arctic Climate Forcers

    NASA Astrophysics Data System (ADS)

    Quinn, P.

    2015-12-01

    The Arctic Monitoring and Assessment Programme (AMAP) established an Expert Group on Short-Lived Climate Forcers (SLCFs) in 2009 with the goal of reviewing the state of science surrounding SLCFs in the Arctic and recommending science tasks to improve the state of knowledge and its application to policy-making. In 2011, the result of the Expert Group's work was published in a technical report entitled The Impact of Black Carbon on Arctic Climate (AMAP, 2011). That report focused entirely on black carbon (BC) and co-emitted organic carbon (OC). The SLCFs Expert Group then expanded its scope to include all species co-emitted with BC as well as tropospheric ozone. An assessment report, entitled Black Carbon and Tropospheric Ozone as Arctic Climate Forcers, was published in 2015. The assessment includes summaries of measurement methods and emissions inventories of SLCFs, atmospheric transport of SLCFs to and within the Arctic, modeling methods for estimating the impact of SLCFs on Arctic climate, model-measurement inter-comparisons, trends in concentrations of SLCFs in the Arctic, and a literature review of Arctic radiative forcing and climate response. In addition, three Chemistry Climate Models and five Chemistry Transport Models were used to calculate Arctic burdens of SLCFs and precursors species, radiative forcing, and Arctic temperature response to the forcing. Radiative forcing was calculated for the direct atmospheric effect of BC, BC-snow/ice effect, and cloud indirect effects. Forcing and temperature response associated with different source sectors (Domestic, Energy+Industry+Waste, Transport, Agricultural waste burning, Forest fires, and Flaring) and source regions (United States, Canada, Russia, Nordic Countries, Rest of Europe, East and South Asia, Arctic, mid-latitudes, tropics, southern hemisphere) were calculated. To enable an evaluation of the cost-effectiveness of regional emission mitigation options, the normalized impacts (i.e., impacts per unit

  13. Climate-Driven Effects of Fire on Winter Habitat for Caribou in the Alaskan-Yukon Arctic

    PubMed Central

    Gustine, David D.; Brinkman, Todd J.; Lindgren, Michael A.; Schmidt, Jennifer I.; Rupp, T. Scott; Adams, Layne G.

    2014-01-01

    Climatic warming has direct implications for fire-dominated disturbance patterns in northern ecosystems. A transforming wildfire regime is altering plant composition and successional patterns, thus affecting the distribution and potentially the abundance of large herbivores. Caribou (Rangifer tarandus) are an important subsistence resource for communities throughout the north and a species that depends on terrestrial lichen in late-successional forests and tundra systems. Projected increases in area burned and reductions in stand ages may reduce lichen availability within caribou winter ranges. Sufficient reductions in lichen abundance could alter the capacity of these areas to support caribou populations. To assess the potential role of a changing fire regime on winter habitat for caribou, we used a simulation modeling platform, two global circulation models (GCMs), and a moderate emissions scenario to project annual fire characteristics and the resulting abundance of lichen-producing vegetation types (i.e., spruce forests and tundra >60 years old) across a modeling domain that encompassed the winter ranges of the Central Arctic and Porcupine caribou herds in the Alaskan-Yukon Arctic. Fires were less numerous and smaller in tundra compared to spruce habitats throughout the 90-year projection for both GCMs. Given the more likely climate trajectory, we projected that the Porcupine caribou herd, which winters primarily in the boreal forest, could be expected to experience a greater reduction in lichen-producing winter habitats (−21%) than the Central Arctic herd that wintered primarily in the arctic tundra (−11%). Our results suggest that caribou herds wintering in boreal forest will undergo fire-driven reductions in lichen-producing habitats that will, at a minimum, alter their distribution. Range shifts of caribou resulting from fire-driven changes to winter habitat may diminish access to caribou for rural communities that reside in fire-prone areas. PMID

  14. Climate-driven effects of fire on winter habitat for caribou in the Alaskan-Yukon Arctic

    USGS Publications Warehouse

    Gustine, David D.; Brinkman, Todd J.; Lindgren, Michael A.; Schmidt, Jennifer I.; Rupp, T. Scott; Adams, Layne G.

    2014-01-01

    Climatic warming has direct implications for fire-dominated disturbance patterns in northern ecosystems. A transforming wildfire regime is altering plant composition and successional patterns, thus affecting the distribution and potentially the abundance of large herbivores. Caribou (Rangifer tarandus) are an important subsistence resource for communities throughout the north and a species that depends on terrestrial lichen in late-successional forests and tundra systems. Projected increases in area burned and reductions in stand ages may reduce lichen availability within caribou winter ranges. Sufficient reductions in lichen abundance could alter the capacity of these areas to support caribou populations. To assess the potential role of a changing fire regime on winter habitat for caribou, we used a simulation modeling platform, two global circulation models (GCMs), and a moderate emissions scenario to project annual fire characteristics and the resulting abundance of lichen-producing vegetation types (i.e., spruce forests and tundra >60 years old) across a modeling domain that encompassed the winter ranges of the Central Arctic and Porcupine caribou herds in the Alaskan-Yukon Arctic. Fires were less numerous and smaller in tundra compared to spruce habitats throughout the 90-year projection for both GCMs. Given the more likely climate trajectory, we projected that the Porcupine caribou herd, which winters primarily in the boreal forest, could be expected to experience a greater reduction in lichen-producing winter habitats (−21%) than the Central Arctic herd that wintered primarily in the arctic tundra (−11%). Our results suggest that caribou herds wintering in boreal forest will undergo fire-driven reductions in lichen-producing habitats that will, at a minimum, alter their distribution. Range shifts of caribou resulting from fire-driven changes to winter habitat may diminish access to caribou for rural communities that reside in fire-prone areas.

  15. Scenarios of 21st-century trans-Arctic shipping for climate studies

    NASA Astrophysics Data System (ADS)

    Stephenson, S. R.; Davis, S. J.; Zender, C. S.; Smith, L. C.

    2013-12-01

    Receding Arctic sea ice coupled with increased resource demand in east Asia have recast the Arctic as an international trade space facilitating export of petroleum and minerals and offering potential alternative pathways for global maritime trade. Several studies have examined the future impact of increased vessel traffic in the Arctic on emissions of greenhouse gases and black carbon (BC); however, the net impact of these emissions on climate forcing in the region is not well understood. Here we present several scenarios of 21st-century trans-Arctic shipping for climate studies. Vessel transits between 5 east Asian ports (Tianjin, Shanghai, Hong Kong, Tokyo/Yokohama, Busan) and 2 European ports (Rotterdam, Hamburg) are estimated from 2010-2050 according to projected sea ice concentration and thickness, trends in cargo export volumes, and vessel ice class and cargo capacity. Sea ice data are represented by a 7-model ensemble mean from CMIP5 under two forcing scenarios (RCP 4.5/8.5). Emissions presented (CO2, CH4, N2O, NOx, SOx, BC) are obtained by convolving projected transits with trends in emissions factors. Results illustrate a range of emissions inventories for the Arctic owing to differences in vessel accessibility, trade volume, routes, and fuel mixtures.

  16. Population limitation in a non-cyclic arctic fox population in a changing climate.

    PubMed

    Pálsson, Snæbjörn; Hersteinsson, Páll; Unnsteinsdóttir, Ester R; Nielsen, Ólafur K

    2016-04-01

    Arctic foxes Vulpes lagopus (L.) display a sharp 3- to 5-year fluctuation in population size where lemmings are their main prey. In areas devoid of lemmings, such as Iceland, they do not experience short-term fluctuations. This study focusses on the population dynamics of the arctic fox in Iceland and how it is shaped by its main prey populations. Hunting statistics from 1958-2003 show that the population size of the arctic fox was at a maximum in the 1950s, declined to a minimum in the 1970s, and increased steadily until 2003. Analysis of the arctic fox population size and their prey populations suggests that fox numbers were limited by rock ptarmigan numbers during the decline period. The recovery of the arctic fox population was traced mostly to an increase in goose populations, and favourable climatic conditions as reflected by the Subpolar Gyre. These results underscore the flexibility of a generalist predator and its responses to shifting food resources and climate changes. PMID:26714829

  17. Observed and projected climate change implications for urban infrastructure and society in the Russian Arctic

    NASA Astrophysics Data System (ADS)

    Streletskiy, D. A.; Shiklomanov, N. I.; Efimov, S. V.; Shkolnik, I.

    2012-12-01

    The discoveries of mineral resources followed by an extensive economic development of the Russian North in 1960s led to a development of complex infrastructure on permafrost and urbanization of the Russian Arctic. Despite the mass migration from the northern regions, followed by the collapse of the Soviet Union and the diminishing government support, the Russian Arctic inherited massive infrastructure and remained predominantly urban. Currently, only in five districts bordering Arctic Ocean more than 1.4 million people live in urban-style buildings built on permafrost. Majority of the buildings are constructed assuming the equilibrium conditions of heat-exchange between atmosphere and permafrost underneath. This is usually achieved by construction on piles with ventilated cellars allowing ground cooling in a winter and shading in a summer. The ability of the foundations to carry structural load or foundation bearing capacity (FBC) depends on permafrost properties and changes according to permafrost temperature and active-layer depth. Climate warming observed in recent decades created conditions of diminishing FBC and resulted in deformations and failures of structures built on permafrost. This work is focused on quantitative assessment of these changes at a regional scale. In order to estimate the role of climate change on stability of structures build according to the passive principle, the permafrost-geotechnical model was developed. The historical changes were assessed by comparing model results for period associated with industrialization and construction boom in the Russian North (1965-1975) and present conditions (1995-2005) using NCEP climatic datasets. Projected changes in FBC according to A2 IPCC scenario for the mid-21st century (2041-2060) relative to baseline period (1981-2000) were assessed using output from the ensemble of MGO RCM climate change simulations. It has been found that substantial decrease in FBC will likely occur for the majority of

  18. Projected changes in regional climate extremes arising from Arctic sea ice loss

    NASA Astrophysics Data System (ADS)

    Screen, James A.; Deser, Clara; Sun, Lantao

    2015-08-01

    The decline in Arctic sea ice cover has been widely documented and it is clear that this change is having profound impacts locally. An emerging and highly uncertain area of scientific research, however, is whether such Arctic change has a tangible effect on weather and climate at lower latitudes. Of particular societal relevance is the open question: will continued Arctic sea ice loss make mid-latitude weather more extreme? Here we analyse idealized atmospheric general circulation model simulations, using two independent models, both forced by projected Arctic sea ice loss in the late twenty-first century. We identify robust projected changes in regional temperature and precipitation extremes arising solely due to Arctic sea ice loss. The likelihood and duration of cold extremes are projected to decrease over high latitudes and over central and eastern North America, but to increase over central Asia. Hot extremes are projected to increase in frequency and duration over high latitudes. The likelihood and severity of wet extremes are projected to increase over high latitudes, the Mediterranean and central Asia; and their intensity is projected to increase over high latitudes and central and eastern Asia. The number of dry days over mid-latitude Eurasia and dry spell duration over high latitudes are both projected to decrease. There is closer model agreement for projected changes in temperature extremes than for precipitation extremes. Overall, we find that extreme weather over central and eastern North America is more sensitive to Arctic sea ice loss than over other mid-latitude regions. Our results are useful for constraining the role of Arctic sea ice loss in shifting the odds of extreme weather, but must not be viewed as deterministic projections, as they do not account for drivers other than Arctic sea ice loss.

  19. Transport Regimes of Air Masses Affecting the Tropospheric Composition of the Canadian and European Arctic During RACEPAC 2014 and NETCARE 2014/2015

    NASA Astrophysics Data System (ADS)

    Bozem, H.; Hoor, P. M.; Koellner, F.; Kunkel, D.; Schneider, J.; Schulz, C.; Herber, A. B.; Borrmann, S.; Wendisch, M.; Ehrlich, A.; Leaitch, W. R.; Willis, M. D.; Burkart, J.; Thomas, J. L.; Abbatt, J.

    2015-12-01

    The Arctic is warming much faster than any other place in the world and undergoes a rapid change dominated by a changing climate in this region. The impact of polluted air masses traveling to the Arctic from various remote sources significantly contributes to the observed climate change, in contrast there are additional local emission sources contributing to the level of pollutants (trace gases and aerosol). Processes affecting the emission and transport of these pollutants are not well understood and need to be further investigated. We present aircraft based trace gas measurements in the Arctic during RACEPAC (2014) and NETCARE (2014 and 2015) with the Polar 6 aircraft of Alfred Wegener Institute (AWI) covering an area from 134°W to 17°W and 68°N to 83°N. We focus on cloud, aerosol and general transport processes of polluted air masses into the high Arctic. Based on CO and CO2 measurements and kinematic 10-day back trajectories we analyze the transport regimes prevalent during spring (RACEPAC 2014 and NETCARE 2015) and summer (NETCARE 2014) in the observed region. Whereas the eastern part of the Canadian Arctic is affected by air masses with their origin in Asia, in the central and western parts of the Canadian and European Arctic air masses from North America are predominant at the time of the measurement. In general the more northern parts of the Arctic were relatively unaffected by pollution from mid-latitudes since air masses mostly travel within the polar dome, being quite isolated. Associated mixing ratios of CO and CO2 fit into the seasonal cycle observed at NOAA ground stations throughout the Arctic, but show a more mid-latitudinal characteristic at higher altitudes. The transition is remarkably sharp and allows for a chemical definition of the polar dome. At low altitudes, synoptic disturbances transport polluted air masses from mid-latitudes into regions of the polar dome. These air masses contribute to the Arctic pollution background, but also

  20. Projected Impact of Climate Change on the Water and Salt Budgets of the Arctic Ocean by a Global Climate Model

    NASA Technical Reports Server (NTRS)

    Miller, James R.; Russell, Gary L.

    1996-01-01

    The annual flux of freshwater into the Arctic Ocean by the atmosphere and rivers is balanced by the export of sea ice and oceanic freshwater. Two 150-year simulations of a global climate model are used to examine how this balance might change if atmospheric greenhouse gases (GHGs) increase. Relative to the control, the last 50-year period of the GHG experiment indicates that the total inflow of water from the atmosphere and rivers increases by 10% primarily due to an increase in river discharge, the annual sea-ice export decreases by about half, the oceanic liquid water export increases, salinity decreases, sea-ice cover decreases, and the total mass and sea-surface height of the Arctic Ocean increase. The closed, compact, and multi-phased nature of the hydrologic cycle in the Arctic Ocean makes it an ideal test of water budgets that could be included in model intercomparisons.

  1. Boreal fire influence on Arctic tropospheric ozone, ecosystems and climate forcing

    NASA Astrophysics Data System (ADS)

    Arnold, S.; Monks, S. A.; Emmons, L. K.; Sitch, S.; Rap, A.; Law, K.; Tilmes, S.; Lamarque, J.

    2013-12-01

    Temperature observations show that the Arctic has warmed rapidly in the past few decades compared to the northern hemisphere as a whole. Model calculations suggest that changes in short-lived pollutants such as ozone and aerosol may have contributed significantly to this warming. Arctic tropospheric budgets of short-lived pollutants are impacted by both local anthropogenic emissions and by long-range transport of gases and aerosols from Europe, Asia and N. America, but also by local Boreal wildfires in summer. Our understanding of how fires impact Arctic budgets of climate-relevant atmospheric constituents is limited, and is reliant on sparse observations and models of tropospheric chemistry. A better understanding of Boreal fire influence on Arctic ozone is essential for improving the reliability of our projections of future Arctic and Northern Hemisphere climate change, especially in light of proposed climate-fire feedbacks which may enhance the intensity and extent of high latitude wildfire under a warming climate. Using the NCAR Community Earth System Model (CESM) and a scheme for tagging and tracking NOx emitted by high latitude wildfires and its resultant tropospheric ozone production, we investigate the impacts of fire-sourced ozone on summertime high latitude radiative forcing and on ecosystems. The large fraction of NOy present as PAN in the Arctic suggests there may be a strong sensitivity of NOy and ozone enhancement to the efficiency of vertical transport from source regions, which determines the stability of PAN as air is advected poleward. We use these simulations and aircraft observations to characterise the vertical distributions of sensitivities of Arctic NOy and ozone to remote anthropogenic and local widlfire sources, and use an offline radiative transfer model to quantify impacts on local ozone radiative forcing. We compare these vertical sensitivities with those of a primary-emitted CO-like source tracer, to investigate the role of PAN

  2. Climate-driven regime shifts in the biological communities of arctic lakes

    PubMed Central

    Smol, John P.; Wolfe, Alexander P.; Birks, H. John B.; Douglas, Marianne S. V.; Jones, Vivienne J.; Korhola, Atte; Pienitz, Reinhard; Rühland, Kathleen; Sorvari, Sanna; Antoniades, Dermot; Brooks, Stephen J.; Fallu, Marie-Andrée; Hughes, Mike; Keatley, Bronwyn E.; Laing, Tamsin E.; Michelutti, Neal; Nazarova, Larisa; Nyman, Marjut; Paterson, Andrew M.; Perren, Bianca; Quinlan, Roberto; Rautio, Milla; Saulnier-Talbot, Émilie; Siitonen, Susanna; Solovieva, Nadia; Weckström, Jan

    2005-01-01

    Fifty-five paleolimnological records from lakes in the circumpolar Arctic reveal widespread species changes and ecological reorganizations in algae and invertebrate communities since approximately anno Domini 1850. The remoteness of these sites, coupled with the ecological characteristics of taxa involved, indicate that changes are primarily driven by climate warming through lengthening of the summer growing season and related limnological changes. The widespread distribution and similar character of these changes indicate that the opportunity to study arctic ecosystems unaffected by human influences may have disappeared. PMID:15738395

  3. How offshore arctic conditions affect drilling mud disposal

    SciTech Connect

    Miller, R.C.; Britch, R.P.; Hillman, S.O.; Shafer, R.V.

    1982-12-01

    Reports on a series of studies and tests, covering a time period from early 1979 to mid-1981, conducted to examine both below-ice and above-ice discharge. Local, state, and federal concern has been expressed over the discharge of drilling effluent in shallow arctic seas contiguous to the northern coast of Alaska. The 1979 studies included monitoring environmental boundary conditions, test discharges of drilling effluents above and below the ice, analysis of drilling effluents, benthic studies, and toxicity testing. Studies in 1980 and 1981 included grain size, trace metal, and hydrocarbon analysis of drilling effluents and seafloor sediments, depositional monitoring, and photographic monitoring of individual aboveice sites. Results show that the fate of drilling fluids disposed of on top of the ice will vary with location within the lease area. Drilling effluents discharged in nearshore areas subject to overflow flooding from major rivers would be widely dispersed during the initial stages of breakup. Depending on the movement of the parent ice sheet during the later stages of breakup, solids may either be deposited on the seafloor beneath the disposal site or be carried with the broken ice sheet and be widely (spatially) and thinly deposited on the seafloor.

  4. Climate Change, Permafrost and Infrastructure: Task Force Report of the U.S. Arctic Research Commission

    NASA Astrophysics Data System (ADS)

    Brigham, L. W.; Nelson, F. E.

    2003-12-01

    During 2002 the U.S. Arctic Research Commission chartered a task force on climate change, permafrost and infrastructure impacts. The task force was asked to identify key issues and research needs to foster a greater understanding of global change impacts on permafrost in the Arctic and their importance to natural and human systems. Permafrost was found to play three key roles in the context of climatic change: as a record keeper by functioning as a temperature archive; as a translator of climate change through subsidence and related impacts; and, as a facilitator of further change through its impacts on the global carbon cycle. Evidence of widespread warming of permafrost and observations of thawing have serious implications for Alaska's transportation network, for the trans-Alaska pipeline, and for nearly 100,000 Alaskans living in areas of permafrost. These impacts resulting from changing permafrost must be met by a timely, well-informed, and coordinated response by a host of federal and state organizations. Key task force findings include: requirements for a dedicated U.S. federal permafrost research program; data management needs; baseline permafrost mapping in Alaska; basic permafrost research focusing on process studies and modeling; and, applied permafrost research on design criteria and contaminants in permafrost environments. This report to the Commissioners makes specific recommendations to seven federal agencies, the State of Alaska, and the National Research Council. These recommendations will be incorporated in future Arctic research planning documents of the U.S. Arctic Research Commission.

  5. Spatial and temporal patterns of greenness on the Yamal Peninsula, Russia: interactions of ecological and social factors affecting the Arctic normalized difference vegetation index

    NASA Astrophysics Data System (ADS)

    Walker, D. A.; Leibman, M. O.; Epstein, H. E.; Forbes, B. C.; Bhatt, U. S.; Raynolds, M. K.; Comiso, J. C.; Gubarkov, A. A.; Khomutov, A. V.; Jia, G. J.; Kaarlejärvi, E.; Kaplan, J. O.; Kumpula, T.; Kuss, P.; Matyshak, G.; Moskalenko, N. G.; Orekhov, P.; Romanovsky, V. E.; Ukraientseva, N. G.; Yu, Q.

    2009-10-01

    The causes of a greening trend detected in the Arctic using the normalized difference vegetation index (NDVI) are still poorly understood. Changes in NDVI are a result of multiple ecological and social factors that affect tundra net primary productivity. Here we use a 25 year time series of AVHRR-derived NDVI data (AVHRR: advanced very high resolution radiometer), climate analysis, a global geographic information database and ground-based studies to examine the spatial and temporal patterns of vegetation greenness on the Yamal Peninsula, Russia. We assess the effects of climate change, gas-field development, reindeer grazing and permafrost degradation. In contrast to the case for Arctic North America, there has not been a significant trend in summer temperature or NDVI, and much of the pattern of NDVI in this region is due to disturbances. There has been a 37% change in early-summer coastal sea-ice concentration, a 4% increase in summer land temperatures and a 7% change in the average time-integrated NDVI over the length of the satellite observations. Gas-field infrastructure is not currently extensive enough to affect regional NDVI patterns. The effect of reindeer is difficult to quantitatively assess because of the lack of control areas where reindeer are excluded. Many of the greenest landscapes on the Yamal are associated with landslides and drainage networks that have resulted from ongoing rapid permafrost degradation. A warming climate and enhanced winter snow are likely to exacerbate positive feedbacks between climate and permafrost thawing. We present a diagram that summarizes the social and ecological factors that influence Arctic NDVI. The NDVI should be viewed as a powerful monitoring tool that integrates the cumulative effect of a multitude of factors affecting Arctic land-cover change.

  6. Regional Arctic System Model (RASM): A Tool to Address the U.S. Priorities and Advance Capabilities for Arctic Climate Modeling and Prediction

    NASA Astrophysics Data System (ADS)

    Maslowski, W.; Roberts, A.; Cassano, J. J.; Gutowski, W. J., Jr.; Nijssen, B.; Osinski, R.; Zeng, X.; Brunke, M.; Duvivier, A.; Hamman, J.; Hossainzadeh, S.; Hughes, M.; Seefeldt, M. W.

    2015-12-01

    The Arctic is undergoing some of the most coordinated rapid climatic changes currently occurring anywhere on Earth, including the retreat of the perennial sea ice cover, which integrates forcing by, exchanges with and feedbacks between atmosphere, ocean and land. While historical reconstructions from Earth System Models (ESMs) are in broad agreement with these changes, the rate of change in ESMs generally remains outpaced by observations. Reasons for that relate to a combination of coarse resolution, inadequate parameterizations, under-represented processes and a limited knowledge of physical interactions. We demonstrate the capability of the Regional Arctic System Model (RASM) in addressing some of the ESM limitations in simulating observed variability and trends in arctic surface climate. RASM is a high resolution, pan-Arctic coupled climate model with the sea ice and ocean model components configured at an eddy-permitting resolution of 1/12o and the atmosphere and land hydrology model components at 50 km resolution, which are all coupled at 20-minute intervals. RASM is an example of limited-area, process-resolving, fully coupled ESM, which due to the constraints from boundary conditions facilitates detailed comparisons with observational statistics that are not possible with ESMs. The overall goal of RASM is to address key requirements published in the Navy Arctic Roadmap: 2014-2030 and in the Implementation Plan for the National Strategy for the Arctic Region, regarding the need for advanced modeling capabilities for operational forecasting and strategic climate predictions through 2030. The main science objectives of RASM are to advance understanding and model representation of critical physical processes and feedbacks of importance to sea ice thickness and area distribution. RASM results are presented to quantify relative contributions by (i) resolved processes and feedbacks as well as (ii) sensitivity to space dependent sub-grid parameterizations to better

  7. Response of ice cover on shallow Arctic lakes to contemporary climate conditions: Numerical modeling and remote sensing data analysis

    NASA Astrophysics Data System (ADS)

    Duguay, C.; Surdu, C.; Brown, L.; Samuelsson, P.

    2012-04-01

    Lake ice cover has been shown to be a robust indicator of climate variability and change. Recent studies have demonstrated that break-up dates, in particular, have been occurring earlier in many parts of the Northern Hemisphere over the last 50 years in response to warmer climatic conditions in the winter and spring seasons. The impacts of trends in air temperature and winter precipitation over the last five decades and those projected by global climate models will affect the timing and duration of ice cover (and ice thickness) on Arctic lakes. This will likely, in turn, have an important feedback effect on energy, water, and biogeochemical cycling in various regions of the Arctic. In the case of shallow tundra lakes, many of which are less than 3-m deep, warmer climate conditions could result in a smaller fraction of lakes that freeze to their bed in winter since thinner ice covers are expected to develop. Shallow lakes of the coastal plain of northern Alaska, and other similar regions of the Arctic, have likely been experiencing changes in seasonal ice thickness (and phenology) over the last few decades but these have not yet been documented. This paper presents results from a numerical lake ice modeling experiment and the analysis of ERS-1/2 synthetic aperture radar (SAR) data to elucidate the response of ice cover (thickness, freezing to bed, and phenology) on shallow lakes of the North Slope of Alaska (NSA)to climate conditions over the last three decades. New downscaled data specific for the Arctic domain (at a resolution of 0.44 degrees using ERA Interim Reanalysis as boundary condition) produced by the Rossby Centre regional atmospheric model (RCA4) was used to force the Canadian Lake Ice Model (CLIMo) for the period 1979-2010. Output from CLIMo included freeze-up and break-up dates as well as ice thickness on a daily basis. ERS-1/2 data was used to map areas of shallow lakes that freeze to bed and when this happens (timing) in winter for the period 1991

  8. Regional climate responses to geoengineering with tropical and Arctic SO2 injections

    NASA Astrophysics Data System (ADS)

    Robock, Alan; Oman, Luke; Stenchikov, Georgiy L.

    2008-08-01

    Anthropogenic stratospheric aerosol production, so as to reduce solar insolation and cool Earth, has been suggested as an emergency response to geoengineer the planet in response to global warming. While volcanic eruptions have been suggested as innocuous examples of stratospheric aerosols cooling the planet, the volcano analog actually argues against geoengineering because of ozone depletion and regional hydrologic and temperature responses. To further investigate the climate response, here we simulate the climate response to both tropical and Arctic stratospheric injection of sulfate aerosol precursors using a comprehensive atmosphere-ocean general circulation model, the National Aeronautics and Space Administration Goddard Institute for Space Studies ModelE. We inject SO2 and the model converts it to sulfate aerosols, transports the aerosols and removes them through dry and wet deposition, and calculates the climate response to the radiative forcing from the aerosols. We conduct simulations of future climate with the Intergovernmental Panel on Climate Change A1B business-as-usual scenario both with and without geoengineering and compare the results. We find that if there were a way to continuously inject SO2 into the lower stratosphere, it would produce global cooling. Tropical SO2 injection would produce sustained cooling over most of the world, with more cooling over continents. Arctic SO2 injection would not just cool the Arctic. Both tropical and Arctic SO2 injection would disrupt the Asian and African summer monsoons, reducing precipitation to the food supply for billions of people. These regional climate anomalies are but one of many reasons that argue against the implementation of this kind of geoengineering.

  9. What can we learn from the Paleo-Records about Future Arctic Climate Change?

    NASA Astrophysics Data System (ADS)

    Tremblay, B.; Huard, D. B.; Schmidt, G. A.; de Vernal, A.

    2014-12-01

    The Coupled Model Intercomparison Project, Phase 5 (CMIP5), include historical simulations from the 20th century, future climate simulations following different Representative Concentration Pathways (RCPs) for the 21st Century and beyond, and, for the first time in CMIP, three sets of paleo-climate simulations of the recent past for which more paleo-proxi-data exist. We use simulations of the Mid-Holocene (MH) climate (6K BP) from General Circulation Models participating in CMIP5 to constrain future projections of Arctic climate change by the same models. During the Mid-Holocene, the Arctic received approximately 50 W/m2 more solar radiation at the top of the atmosphere during summer, a similar increase to what is projected from greenhouse gas forcing for the middle of the 21st century. The constraint in our analysis arise from a measure of the ability of GCMs to hindcast MH climate using a suite of both land paleo-records - which are much more abundant for high latitudes than ocean proxy - and ocean paleo-record. Results show that GCMs with skill at simulating the MH climate and today's climate give more realistic future projections of the sea ice decline in forced climate simulations of the 21st century participating in the IPCC-AR5.

  10. Climate Trends in the Arctic as Observed from Space

    NASA Technical Reports Server (NTRS)

    Comiso, Josefino C.; Hall, Dorothy K.

    2014-01-01

    The Arctic is a region in transformation. Warming in the region has been amplified, as expected from ice-albedo feedback effects, with the rate of warming observed to be approx. 0.60+/-0.07 C/decade in the Arctic (>64degN) compared to approx. 0.17 C/decade globally during the last three decades. This increase in surface temperature is manifested in all components of the cryosphere. In particular, the sea ice extent has been declining at the rate of approx. 3.8%/decade, whereas the perennial ice (represented by summer ice minimum) is declining at a much greater rate of approx.11.5%/decade. Spring snow cover has also been observed to be declining by -2.12%/decade for the period 1967-2012. The Greenland ice sheet has been losing mass at the rate of approx. 34.0Gt/year (sea level equivalence of 0.09 mm/year) during the period from 1992 to 2011, but for the period 2002-2011, a higher rate of mass loss of approx. 215 Gt/year has been observed. Also, the mass of glaciers worldwide declined at the rate of 226 Gt/year from 1971 to 2009 and 275 Gt/year from 1993 to 2009. Increases in permafrost temperature have also been measured in many parts of the Northern Hemisphere while a thickening of the active layer that overlies permafrost and a thinning of seasonally frozen ground has also been reported. To gain insight into these changes, comparative analysis with trends in clouds, albedo, and the Arctic Oscillation is also presented.

  11. Climate trends in the Arctic as observed from space

    PubMed Central

    Comiso, Josefino C; Hall, Dorothy K

    2014-01-01

    The Arctic is a region in transformation. Warming in the region has been amplified, as expected from ice-albedo feedback effects, with the rate of warming observed to be ∼0.60 ± 0.07°C/decade in the Arctic (>64°N) compared to ∼0.17°C/decade globally during the last three decades. This increase in surface temperature is manifested in all components of the cryosphere. In particular, the sea ice extent has been declining at the rate of ∼3.8%/decade, whereas the perennial ice (represented by summer ice minimum) is declining at a much greater rate of ∼11.5%/decade. Spring snow cover has also been observed to be declining by −2.12%/decade for the period 1967–2012. The Greenland ice sheet has been losing mass at the rate of ∼34.0 Gt/year (sea level equivalence of 0.09 mm/year) during the period from 1992 to 2011, but for the period 2002–2011, a higher rate of mass loss of ∼215 Gt/year has been observed. Also, the mass of glaciers worldwide declined at the rate of 226 Gt/year from 1971 to 2009 and 275 Gt/year from 1993 to 2009. Increases in permafrost temperature have also been measured in many parts of the Northern Hemisphere while a thickening of the active layer that overlies permafrost and a thinning of seasonally frozen ground has also been reported. To gain insight into these changes, comparative analysis with trends in clouds, albedo, and the Arctic Oscillation is also presented. How to cite this article:WIREs Clim Change 2014, 5:389�409. doi: 10.1002/wcc.277 PMID:25810765

  12. Pliocene Climate variability at Lake El'gygytgyn, NE Arctic Russia, western Beringia

    NASA Astrophysics Data System (ADS)

    Brigham-Grette, J.; Melles, M.; Minyuk, P. S.

    2013-12-01

    The new record from Lake El'gygytgyn, NE arctic Russia provides the first complete record of Pliocene climate change from the terrestrial Arctic. Lake El'gygytgyn evidence shows 3.6-3.4 Ma ago summer temperatures were ~8oC warmer than today when pCO2 was ~400 ppm. Multiproxy evidence suggests extreme warmth and polar amplification during the middle Pliocene with low amplitude changes between cold and warm Milankovitch cycles consistent with the LR stack. Sudden stepped cooling events during the Pliocene-Pleistocene transition recorded at Lake E are consistent with marine proxies from the North Pacific and North Atlantic suggesting that polar amplification was recorded across the northern hemisphere in both marine and Arctic terrestrial environments. Summers warmer than present Arctic persisted until ~2.2 Ma, after the onset of Northern Hemispheric glaciation. Our data are consistent with sea-level records and other proxies indicating that Arctic cooling was really insufficient to support large-scale ice sheets until the early Pleistocene.

  13. The Opening of the Arctic-Atlantic Gateway: Tectonic, Oceanographic and Climatic Dynamics - an IODP Initiative

    NASA Astrophysics Data System (ADS)

    Geissler, Wolfram; Knies, Jochen

    2016-04-01

    The modern polar cryosphere reflects an extreme climate state with profound temperature gradients towards high-latitudes. It developed in association with stepwise Cenozoic cooling, beginning with ephemeral glaciations and the appearance of sea ice in the late middle Eocene. The polar ocean gateways played a pivotal role in changing the polar and global climate, along with declining greenhouse gas levels. The opening of the Drake Passage finalized the oceanographic isolation of Antarctica, some 40 Ma ago. The Arctic Ocean was an isolated basin until the early Miocene when rifting and subsequent sea-floor spreading started between Greenland and Svalbard, initiating the opening of the Fram Strait / Arctic-Atlantic Gateway (AAG). Although this gateway is known to be important in Earth's past and modern climate, little is known about its Cenozoic development. However, the opening history and AAG's consecutive widening and deepening must have had a strong impact on circulation and water mass exchange between the Arctic Ocean and the North Atlantic. To study the AAG's complete history, ocean drilling at two primary sites and one alternate site located between 73°N and 78°N in the Boreas Basin and along the East Greenland continental margin are proposed. These sites will provide unprecedented sedimentary records that will unveil (1) the history of shallow-water exchange between the Arctic Ocean and the North Atlantic, and (2) the development of the AAG to a deep-water connection and its influence on the global climate system. The specific overarching goals of our proposal are to study: (1) the influence of distinct tectonic events in the development of the AAG and the formation of deep water passage on the North Atlantic and Arctic paleoceanography, and (2) the role of the AAG in the climate transition from the Paleogene greenhouse to the Neogene icehouse for the long-term (~50 Ma) climate history of the northern North Atlantic. Getting a continuous record of the

  14. Influence of climate change on the Arctic Contamination Potential

    NASA Astrophysics Data System (ADS)

    Hansen, Kaj M.; Christensen, Jesper H.; Brandt, Jørgen

    2014-05-01

    Using the Danish Eulerian Hemispheric Model (DEHM) we have calculated the Arctic Contamination Potential (ACP). ACP is defined as the sum of masses in the arctic surface compartments (soil, vegetation, snow and water) at the end of a ten year simulated period normalised either with the total mass within the model domain of with the total amount emitted into the atmosphere during the ten year simulation. In this study we use the emission normalized ACP termed eACP. We have calculated the eACP for the physical-chemical phase space spanned by compounds with log Koa between 3 and 12 and log Kaw between -4 and 3 and for each point in this phase space grid we have included a perfectly persistent compound in the model. DEHM is a 3-D atmospheric chemistry-transport model modelling the atmospheric transport of four chemical groups: a group with SOx-NOx-VOC-ozone chemistry, a group with primary particulates group, a mercury chemistry group, and finally a group with Persistent Organic Pollutants with 2-d surface compartments (soil, vegetation, ocean water and a dynamic temporal snow cover) with inter-compartmental mass exchange process parameterizations. The model domain covers the Northern Hemisphere and thus includes all important source areas for the Arctic. The spatial horizontal resolution of the model system in this work is 150km x 150km and the model includes 20 vertical levels up to approximately 15km above the surface. The model system was run with meteorology obtain from ECHAM5/MPI-OM (SRES A1B scenario) for two decades: 1990-1999 and 2090-2099. Highest potential (12%) for reaching the Arctic surface compartments for the 1990s is seen for compounds with low log Koa and low log Kaw values. These are relative water soluble compounds referred to as "swimmers". For the 2090s, the overall pattern of the ACP phase space is similar to the pattern for the 1990s. ACP is generally larger for the 2090s than for the 1990s, with a maximum of 15%.

  15. Tracking Particulate Organic Matter Characteristics in Major Arctic Rivers: Indicators of Watershed-Scale Climate Impacts

    NASA Astrophysics Data System (ADS)

    McClelland, J. W.; Griffin, C. G.; Holmes, R. M.; Peterson, B. J.; Raymond, P. A.; Spencer, R. G.; Striegl, R. G.; Tank, S. E.

    2015-12-01

    Six large rivers, including the Yukon and Mackenzie in North America and the Yenisey, Ob', Lena, and Kolyma in Eurasia, drain the majority of the watershed area surrounding the Arctic Ocean. Parallel sampling programs were initiated at downstream locations on these rivers in 2003 to improve estimates of fluvial export and track large-scale perturbations associated with climate change. Over a decade later, synthesis of water chemistry data from these ongoing sampling efforts provides an unprecedented opportunity to 1) examine similarities and differences among the major Arctic rivers, and 2) think critically about how changes in various water chemistry parameters may or may not inform us about climate change impacts. River-borne organic matter characteristics may be particularly telling because mass flux values and composition/source indicators vary with hydrology and permafrost coverage. However, separating climate impacts that occur within river corridors from those that occur beyond them may be difficult, especially when considering changes in particulate organic matter (POM) loads. Data on suspended POM yields, C:N ratios, stable isotope ratios, and radiocarbon content in the major Arctic rivers show marked spatial, seasonal, and interannual variability that is helpful for thinking about how climate change effects may manifest in the future, but it will be challenging to separate changes in POM related to bank erosion and suspension/deposition of in situ sediment stocks from changes in POM that may be linked to processes such as permafrost thaw occurring across the broader landscape.

  16. Changes in Arctic and Antarctic Sea Ice as a Microcosm of Global Climate Change

    NASA Technical Reports Server (NTRS)

    Parkinson, Claire L.

    2014-01-01

    Polar sea ice is a key element of the climate system and has now been monitored through satellite observations for over three and a half decades. The satellite observations reveal considerable information about polar ice and its changes since the late 1970s, including a prominent downward trend in Arctic sea ice coverage and a much lesser upward trend in Antarctic sea ice coverage, illustrative of the important fact that climate change entails spatial contrasts. The decreasing ice coverage in the Arctic corresponds well with contemporaneous Arctic warming and exhibits particularly large decreases in the summers of 2007 and 2012, influenced by both preconditioning and atmospheric conditions. The increasing ice coverage in the Antarctic is not as readily explained, but spatial differences in the Antarctic trends suggest a possible connection with atmospheric circulation changes that have perhaps been influenced by the Antarctic ozone hole. The changes in the polar ice covers and the issues surrounding those changes have many commonalities with broader climate changes and their surrounding issues, allowing the sea ice changes to be viewed in some important ways as a microcosm of global climate change.

  17. Climate, Plant Biomass, NDVI, and LAI Relationships Along The Full Arctic Bioclimate Gradient

    NASA Astrophysics Data System (ADS)

    Epstein, H. E.; Walker, D. A.; Jia, G. J.; Kelley, A. M.

    2005-12-01

    A common methodology for assessing the potential effects of terrestrial ecosystems to environmental change is to develop present-day spatial relationships between environmental variables and ecosystem properties. Spatial relationships between climate variables and ecosystem variables should of course be used cautiously when extrapolating these patterns over time, i.e. space-for-time substitutions. Nevertheless, this approach has been extremely useful along regional climate gradients, in addition to providing support for vegetation dynamics models. We are developing several datasets of latitude, temperature, aboveground plant biomass, the NDVI (normalized difference vegetation index) and LAI (leaf area index) for arctic tundra ecosystems along an 1800-km transect from the Low Arctic tundra in northern Alaska to the Polar Desert of the northern Canadian Archipelago. Another useful application of these data is the relationships between NDVI and aboveground plant biomass, which can allow for the conversion of satellite data to on-the-ground ecosystem properties. For the portion of our transect on the northern slope of Alaska, NDVI (from NOAA AVHRR data) decreased with increasing latitude, explaining 45% of the variance in LAI, 65% of aboveground biomass and 42% of shrub biomass. Along the same portion of the transect, LAI (measured from above the mosses and lichens) explained 69% of vascular plant biomass and 68% of shrub biomass. For the higher arctic portion of the transect, NDVI (measured using a handheld spectroradiometer) continued to decrease with latitude, and latitude explained 90% of the variation in NDVI. For these sites in the High Arctic, NDVI was most strongly related to the sum of moss and graminoid biomass (r2=0.60). Ultimately, our dataset will contain climate data, satellite NDVI, handheld NDVI, LAI, and various components of aboveground plant biomass for a complete synthesis along the full arctic bioclimate gradient.

  18. Eocene climate and Arctic paleobathymetry: A tectonic sensitivity study using GISS ModelE-R

    NASA Astrophysics Data System (ADS)

    Roberts, C. D.; Legrande, A. N.; Tripati, A. K.

    2009-12-01

    The early Paleogene (65-45 million years ago, Ma) was a ‘greenhouse’ interval with global temperatures warmer than any other time in the last 65 Ma. This period was characterized by high levels of CO2, warm high-latitudes, warm surface-and-deep oceans, and an intensified hydrological cycle. Sediments from the Arctic suggest that the Eocene surface Arctic Ocean was warm, brackish, and episodically enabled the freshwater fern Azolla to bloom. The precise mechanisms responsible for the development of these conditions remain uncertain. We present equilibrium climate conditions derived from a fully-coupled, water-isotope enabled, general circulation model (GISS ModelE-R) configured for the early Eocene. We also present model-data comparison plots for key climatic variables (SST and δ18O) and analyses of the leading modes of variability in the tropical Pacific and North Atlantic regions. Our tectonic sensitivity study indicates that Northern Hemisphere climate would have been very sensitive to the degree of oceanic exchange through the seaways connecting the Arctic to the Atlantic and Tethys. By restricting these seaways, we simulate freshening of the surface Arctic Ocean to ~6 psu and warming of sea-surface temperatures by 2°C in the North Atlantic and 5-10°C in the Labrador Sea. Our results may help explain the occurrence of low-salinity tolerant taxa in the Arctic Ocean during the Eocene and provide a mechanism for enhanced warmth in the north western Atlantic. We also suggest that the formation of a volcanic land-bridge between Greenland and Europe could have caused increased ocean convection and warming of intermediate waters in the Atlantic. If true, this result is consistent with the theory that bathymetry changes may have caused thermal destabilisation of methane clathrates in the Atlantic.

  19. Short-lived pollutants in the Arctic: their climate impact and possible mitigation strategies

    SciTech Connect

    Menon, Surabi; Quinn, P.K.; Bates, T.S.; Baum, E.; Doubleday, N.; Fiore, A.M.; Flanner, M.; Fridlind, A.; Garrett, T.J.; Koch, D.; Menon, S.; Shindell, D.; Stohl, A.; Warren, S.G.

    2007-09-24

    Several short-lived pollutants known to impact Arctic climate may be contributing to the accelerated rates of warming observed in this region relative to the global annually averaged temperature increase. Here, we present a summary of the short-lived pollutants that impact Arctic climate including methane, tropospheric ozone, and tropospheric aerosols. For each pollutant, we provide a description of the major sources and the mechanism of forcing. We also provide the first seasonally averaged forcing and corresponding temperature response estimates focused specifically on the Arctic. The calculations indicate that the forcings due to black carbon, methane, and tropospheric ozone lead to a positive surface temperature response indicating the need to reduce emissions of these species within and outside the Arctic. Additional aerosol species may also lead to surface warming if the aerosol is coincident with thin, low lying clouds. We suggest strategies for reducing the warming based on current knowledge and discuss directions for future research to address the large remaining uncertainties.

  20. Declining Sea Ice Extent Links Early Winter Climate to Changing Arctic Lakes

    NASA Astrophysics Data System (ADS)

    Alexeev, V. A.; Arp, C. D.; Jones, B. M.; Cai, L.

    2015-12-01

    Lakes on the Alaskan North Slope regulate surface energy balance and interactions with permafrost as well as providing important habitat. Winter lake ice regimes (floating-ice or bedfast-ice conditions) determine whether lakes develop and maintain taliks and can support overwintering fish habitat. Lake ice thickness is a key variable determining whether a lake has a bedfast or floating-ice regime. Recent observations suggest a trend towards more lakes with floating-ice conditions due to thinner ice growth, but the broader scale associated climate conditions driving these regime shift are less certain. This study finds that the changing arctic summer/fall sea ice conditions might be affecting lake ice thickness on the North Slope. Late ocean freeze-up near the Alaskan coast leads to warmer weather and more snowfall in the early winter. Warmer early winters and thicker snowpack result in thinner lake ice the following winter thus potentially developing more ice-floating lakes before the start of the summer. Experiments with a regional atmospheric model WRF for two years with very different sea ice conditions indicate that the extent of open water next to the North Slope is a crucial factor for developing thicker snowpack, also warmer air temperature in early winter.

  1. Signs of the Land: Reaching Arctic Communities Facing Climate Change

    NASA Astrophysics Data System (ADS)

    Sparrow, E. B.; Chase, M. J.; Demientieff, S.; Pfirman, S. L.; Brunacini, J.

    2014-12-01

    In July 2014, a diverse and intergenerational group of Alaskan Natives came together on Howard Luke's Galee'ya Camp by the Tanana River in Fairbanks, Alaska to talk about climate change and it's impacts on local communities. Over a period of four days, the Signs of the Land Climate Change Camp wove together traditional knowledge, local observations, Native language, and climate science through a mix of storytelling, presentations, dialogue, and hands-on, community-building activities. This camp adapted the model developed several years ago under the Association for Interior Native Educators (AINE)'s Elder Academy. Part of the Polar Learning and Responding Climate Change Education Partnership, the Signs of the Land Climate Change Camp was developed and conducted collaboratively with multiple partners to test a model for engaging indigenous communities in the co-production of climate change knowledge, communication tools, and solutions-building. Native Alaskans have strong subsistence and cultural connections to the land and its resources, and, in addition to being keen observers of their environment, have a long history of adapting to changing conditions. Participants in the camp included Elders, classroom teachers, local resource managers and planners, community members, and climate scientists. Based on their experiences during the camp, participants designed individualized outreach plans for bringing culturally-responsive climate learning to their communities and classrooms throughout the upcoming year. Plans included small group discussions, student projects, teacher training, and conference presentations.

  2. A High-Latitude Winter Continental Low Cloud Feedback Suppresses Arctic Air Formation in Warmer Climates

    NASA Astrophysics Data System (ADS)

    Cronin, T.; Tziperman, E.; Li, H.

    2015-12-01

    High latitude continents have warmed much more rapidly in recent decades than the rest of the globe, especially in winter, and the maintenance of warm, frost-free conditions in continental interiors in winter has been a long-standing problem of past equable climates. It has also been found that the high-latitude lapse rate feedback plays an important role in Arctic amplification of climate change in climate model simulations, but we have little understanding of why lapse rates at high latitudes change so strongly with warming. To better understand these problems, we study Arctic air formation - the process by which a high-latitude maritime air mass is advected over a continent during polar night, cooled at the surface by radiation, and transformed into a much colder continental polar air mass - and its sensitivity to climate warming. We use a single-column version of the WRF model to conduct two-week simulations of the cooling process across a wide range of initial temperature profiles and microphysics schemes, and find that a low cloud feedback suppresses Arctic air formation in warmer climates. This cloud feedback consists of an increase in low cloud amount with warming, which shields the surface from radiative cooling, and increases the continental surface air temperature by roughly two degrees for each degree increase of the initial maritime surface air temperature. The time it takes for the surface air temperature to drop below freezing increases nonlinearly to ~10 days for initial maritime surface air temperatures of 20 oC. Given that this is about the time it takes an air mass starting over the Pacific to traverse the north American continent, this suggests that optically thick stratus cloud decks could help to maintain frost-free winter continental interiors in equable climates. We find that CMIP5 climate model runs show large increases in cloud water path and surface cloud longwave forcing in warmer climates, consistent with the proposed low-cloud feedback

  3. Toward daily climate scenarios for Canadian Arctic coastal zones with more realistic temperature-precipitation interdependence

    NASA Astrophysics Data System (ADS)

    Gennaretti, Fabio; Sangelantoni, Lorenzo; Grenier, Patrick

    2015-12-01

    The interdependence between climatic variables should be taken into account when developing climate scenarios. For example, temperature-precipitation interdependence in the Arctic is strong and impacts on other physical characteristics, such as the extent and duration of snow cover. However, this interdependence is often misrepresented in climate simulations. Here we use two two-dimensional (2-D) methods for statistically adjusting climate model simulations to develop plausible local daily temperature (Tmean) and precipitation (Pr) scenarios. The first 2-D method is based on empirical quantile mapping (2Dqm) and the second on parametric copula models (2Dcopula). Both methods are improved here by forcing the preservation of the modeled long-term warming trend and by using moving windows to obtain an adjustment specific to each day of the year. These methods were applied to a representative ensemble of 13 global climate model simulations at 26 Canadian Arctic coastal sites and tested using an innovative cross-validation approach. Intervariable dependence was evaluated using correlation coefficients and empirical copula density plots. Results show that these 2-D methods, especially 2Dqm, adjust individual distributions of climatic time series as adequately as one common one-dimensional method (1Dqm) does. Furthermore, although 2Dqm outperforms the other methods in reproducing the observed temperature-precipitation interdependence over the calibration period, both 2Dqm and 2Dcopula perform similarly over the validation periods. For cases where temperature-precipitation interdependence is important (e.g., characterizing extreme events and the extent and duration of snow cover), both 2-D methods are good options for producing plausible local climate scenarios in Canadian Arctic coastal zones.

  4. Wave climate and trends along the eastern Chukchi Arctic Alaska coast

    USGS Publications Warehouse

    Erikson, L.H.; Storlazzi, C.D.; Jensen, R.E.

    2011-01-01

    Due in large part to the difficulty of obtaining measurements in the Arctic, little is known about the wave climate along the coast of Arctic Alaska. In this study, numerical model simulations encompassing 40 years of wave hind-casts were used to assess mean and extreme wave conditions. Results indicate that the wave climate was strongly modulated by large-scale atmospheric circulation patterns and that mean and extreme wave heights and periods exhibited increasing trends in both the sea and swell frequency bands over the time-period studied (1954-2004). Model simulations also indicate that the upward trend was not due to a decrease in the minimum icepack extent. ?? 2011 ASCE.

  5. Pcw/phemos for Arctic Weather, Climate and Air Quality: a Quasi-Geostationary View of the Arctic and Environs

    NASA Astrophysics Data System (ADS)

    McConnell, J. C.; O'Neill, N. T.; McElroy, C. T.; Solheim, B.; Buijs, H.; Rahnama, P.; Walker, K. A.; Martin, R. V.; Sioris, C.; Garand, L.; Trichtchenko, A.; Nassar, R.

    2011-12-01

    The Arctic is a region of rapid climate change with warming temperatures and depleting multi-year ice which may be exacerbated by transport of black carbon from the burning of the boreal forest and anthropogenic material from mid- and high-latitudes. It is also the source of winter storms delivering cold air to lower latitudes. Currently data are available for these areas from polar orbiting satellites, but only intermittently at a given location as the satellites pass overhead. The Canadian Space Agency, in concert with other government departments, is considering launching the PCW (Polar Communications and Weather) mission which would use two satellites each in a 16 hour TAP or 12 hour Molniya orbit (very high eccentricity with an apogee of ~ 6Re) which is a quasi-stationary orbit close to apogee ( 4 hours) to give 24x7 (continuous) coverage of the Arctic region. The baseline PCW meteorological instrument which would deliver operational meteorological data to the forecasting community is a 20-channel spectral imager similar to MODIS or ABI. The CSA is exploring the possibility of science instruments for atmospheric, plasma and auroral science. Currently the CSA has launched a Phase-A study for the development of an atmospheric package, called PHEMOS, led by ABB Bomen, with COM DEV and a group of atmospheric scientists from university and government. We will present the case for the development of a suite of innovative imaging instruments to provide essential Arctic weather, climate and air quality data from the PCW satellites. The science goals of the PHEMOS instruments (imaging FTS, UV-Vis spectrometer) in concert with those of the PCW multi-spectral imager are the provision of basic weather information, the collection of synoptic-scale air quality (gas and aerosol) measurements to better understand the impact of industrial and agricultural pollution, boreal forest fire smoke and volcanic aerosols on mid- and high latitudes as well as the acquisition of column

  6. Collaborative Research. Quantifying Climate Feedbacks of the Terrestrial Biosphere under Thawing Permafrost Conditions in the Arctic

    SciTech Connect

    Zhuang, Qianlai; Schlosser, Courtney; Melillo, Jerry; Walter, Katey

    2015-09-15

    Our overall goal is to quantify the potential for threshold changes in natural emission rates of trace gases, particularly methane and carbon dioxide, from pan-arctic terrestrial systems under the spectrum of anthropogenically-forced climate warming, and the conditions under which these emissions provide a strong feedback mechanism to global climate warming. This goal is motivated under the premise that polar amplification of global climate warming will induce widespread thaw and degradation of the permafrost, and would thus cause substantial changes to the landscape of wetlands and lakes, especially thermokarst (thaw) lakes, across the Arctic. Through a suite of numerical experiments that encapsulate the fundamental processes governing methane emissions and carbon exchanges – as well as their coupling to the global climate system - we intend to test the following hypothesis in the proposed research: There exists a climate warming threshold beyond which permafrost degradation becomes widespread and stimulates large increases in methane emissions (via thermokarst lakes and poorly-drained wetland areas upon thawing permafrost along with microbial metabolic responses to higher temperatures) and increases in carbon dioxide emissions from well-drained areas. Besides changes in biogeochemistry, this threshold will also influence global energy dynamics through effects on surface albedo, evapotranspiration and water vapor. These changes would outweigh any increased uptake of carbon (e.g. from peatlands and higher plant photosynthesis) and would result in a strong, positive feedback to global climate warming.

  7. Recent climate change in the Arctic and its impact on contaminant pathways and interpretation of temporal trend data.

    PubMed

    Macdonald, R W; Harner, T; Fyfe, J

    2005-04-15

    possibility, presently difficult to predict, is combination of immune suppression together with expanding ranges of disease vectors. Finally, biotransport through migratory species is exceptionally vulnerable to changes in migration strength or in migration pathway-in the Arctic, change in the distribution of ice and temperature may already have caused such changes. Hydrocarbons, which tend to impact surfaces, will be mostly affected by change in the ice climate (distribution and drift tracks). Perhaps the most dramatic changes will occur because our view of the Arctic Ocean will change as it becomes more amenable to transport, tourism and mineral exploration on the shelves. Radionuclides have tended not to produce a radiological problem in the Arctic; nevertheless one pathway, the ice, remains a risk because it can accrue, concentrate and transport radio-contaminated sediments. This pathway is sensitive to where ice is produced, what the transport pathways of ice are, and where ice is finally melted-all strong candidates for change during the coming century. The changes that have already occurred in the Arctic and those that are projected to occur have an effect on contaminant time series including direct measurements (air, water, biota) or proxies (sediment cores, ice cores, archive material). Although these 'system' changes can alter the flux and concentrations at given sites in a number of obvious ways, they have been all but ignored in the interpretation of such time series. To understand properly what trends mean, especially in complex 'recorders' such as seals, walrus and polar bears, demands a more thorough approach to time series by collecting data in a number of media coherently. Presently, a major reservoir for contaminants and the one most directly connected to biological uptake in species at greatest risk-the ocean-practically lacks such time series. PMID:15866268

  8. Arctic sea ice area in CMIP3 and CMIP5 climate model ensembles - variability and change

    NASA Astrophysics Data System (ADS)

    Semenov, V. A.; Martin, T.; Behrens, L. K.; Latif, M.

    2015-02-01

    The shrinking Arctic sea ice cover observed during the last decades is probably the clearest manifestation of ongoing climate change. While climate models in general reproduce the sea ice retreat in the Arctic during the 20th century and simulate further sea ice area loss during the 21st century in response to anthropogenic forcing, the models suffer from large biases and the model results exhibit considerable spread. The last generation of climate models from World Climate Research Programme Coupled Model Intercomparison Project Phase 5 (CMIP5), when compared to the previous CMIP3 model ensemble and considering the whole Arctic, were found to be more consistent with the observed changes in sea ice extent during the recent decades. Some CMIP5 models project strongly accelerated (non-linear) sea ice loss during the first half of the 21st century. Here, complementary to previous studies, we compare results from CMIP3 and CMIP5 with respect to regional Arctic sea ice change. We focus on September and March sea ice. Sea ice area (SIA) variability, sea ice concentration (SIC) variability, and characteristics of the SIA seasonal cycle and interannual variability have been analysed for the whole Arctic, termed Entire Arctic, Central Arctic and Barents Sea. Further, the sensitivity of SIA changes to changes in Northern Hemisphere (NH) averaged temperature is investigated and several important dynamical links between SIA and natural climate variability involving the Atlantic Meridional Overturning Circulation (AMOC), North Atlantic Oscillation (NAO) and sea level pressure gradient (SLPG) in the western Barents Sea opening serving as an index of oceanic inflow to the Barents Sea are studied. The CMIP3 and CMIP5 models not only simulate a coherent decline of the Arctic SIA but also depict consistent changes in the SIA seasonal cycle and in the aforementioned dynamical links. The spatial patterns of SIC variability improve in the CMIP5 ensemble, particularly in summer. Both

  9. An assessment of leaf wax hydrogen isotopes as a climate proxy in proglacial arctic lake sediments

    NASA Astrophysics Data System (ADS)

    Thomas, E. K.; Huang, Y.; Briner, J. P.; McGrane, S.

    2010-12-01

    High-resolution (sub-decadal), Holocene quantitative climate records can be difficult to obtain from lakes in the arctic. Varved lake sediments, which yield annual climate records, rarely extend beyond the past millennium. Paleoecological-based climate reconstructions (e.g., from pollen and chironomid taxa) are time-consuming to obtain, require large amounts of sediment, and in some cases do not respond at high-resolution time scales (e.g., pollen). Therefore, sub-decadally resolved ecological records can be produced only from organic-rich sediments with very high sedimentation rates, which is uncommon in most of the arctic. Compound-specific isotopes of leaf waxes are more rapid to measure and require less sediment than many other climate proxies. Furthermore, current analytical abilities detect measurable concentrations of leaf waxes even in mineral-rich proglacial lake sediments. Proglacial lakes have orders of magnitude higher sedimentation rates than non-glacial lakes, and thus offer great potential for novel, high-resolution arctic climate records. Here, we isolate and analyze leaf wax (n-acid) hydrogen isotope ratios (δDlw) from sediments from three proglacial lakes on Baffin Island, Arctic Canada. Leaf waxes reflect δDprecip, which is controlled by several factors including temperature and precipitation source area. Although extensive work has been conducted on leaf wax isotopes as a climate proxy at low latitudes, there has been much less research near the poles. We analyzed samples at three different resolutions: one lake at annual or biennial resolution (from varved sediments) spanning the past 50 years, one at sub-centennial resolution spanning the past 2.5 kyr, and the last at sub-millennial resolution spanning the past 8 kyr. We compare each of these records to existing regional instrumental and reconstructed climate records. On the millennial scale, δDlw is more enriched when glacier extent was smaller during the middle Holocene, indicating that

  10. Assessing the links between Greenland Ice Sheet Surface Mass Balance and Arctic climate using Climate Models and Observations

    NASA Astrophysics Data System (ADS)

    Mottram, Ruth; Rodehacke, Christian; Boberg, Fredrik; Langen, Peter; Sloth Madsen, Marianne; Høyer Svendsen, Synne; Yang, Shuting; Hesselbjerg Christensen, Jens; Olesen, Martin

    2016-04-01

    Changes in different parts of the Arctic cryosphere may have knock-on effects on other parts of the system. The fully coupled climate model EC-Earth, which includes the ice sheet model PISM, is a useful tool to examine interactions between sea ice, ice sheet, ocean and atmosphere. Here we present results from EC-Earth experimental simulations that show including an interactive ice sheet model changes ocean circulation, sea ice extent and regional climate with, for example, a dampening of the expected increase in Arctic temperatures under the RCP scenarios when compared with uncoupled experiments. However, the relatively coarse resolution of the climate model likely influences the calculated surface mass balance forcing applied to the ice sheet model and it is important therefore to evaluate the model performance over the ice sheet. Here, we assess the quality of the climate forcing from the GCM to the ice sheet model by comparing the energy balance and surface mass balance (SMB) output from EC-Earth with that from a regional climate model (RCM) run at very high resolution (0.05 degrees) over Greenland. The RCM, HIRHAM5, has been evaluated over a wide range of climate parameters for Greenland which allows us to be confident it gives a representative climate forcing for the Greenland ice sheet. To evaluate the internal variability in the climate forcing, we compare simulations from HIRHAM5 forced with both the EC-Earth historical emissions and the ERA-Interim reanalysis on the boundaries. The EC-Earth-PISM RCP8.5 scenario is also compared with an EC-Earth run without an ice sheet to assess the impact of an interactive ice sheet on likely future changes. To account for the resolution difference between the models we downscale both EC-Earth and HIRHAM5 simulations with a simple offline energy balance model (EBM).

  11. Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC)

    NASA Astrophysics Data System (ADS)

    Dethloff, Klaus; Rex, Markus; Shupe, Matthew

    2016-04-01

    The Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) is an international initiative under the International Arctic Science Committee (IASC) umbrella that aims to improve numerical model representations of sea ice, weather, and climate processes through coupled system observations and modeling activities that link the central Arctic atmosphere, sea ice, ocean, and the ecosystem. Observations of many critical parameters such as cloud properties, surface energy fluxes, atmospheric aerosols, small-scale sea-ice and oceanic processes, biological feedbacks with the sea-ice ice and ocean, and others have never been made in the central Arctic in all seasons, and certainly not in a coupled system fashion. The primary objective of MOSAiC is to develop a better understanding of these important coupled-system processes so they can be more accurately represented in regional- and global-scale weather- and climate models. Such enhancements will contribute to improved modeling of global climate and weather, and Arctic sea-ice predictive capabilities. The MOSAiC observations are an important opportunity to gather the high quality and comprehensive observations needed to improve numerical modeling of critical, scale-dependent processes impacting Arctic predictability given diminished sea ice coverage and increased model complexity. Model improvements are needed to understand the effects of a changing Arctic on mid-latitude weather and climate. MOSAiC is specifically designed to provide the multi-parameter, coordinated observations needed to improve sub-grid scale model parameterizations especially with respect to thinner ice conditions. To facilitate, evaluate, and develop the needed model improvements, MOSAiC will employ a hierarchy of modeling approaches ranging from process model studies, to regional climate model intercomparisons, to operational forecasts and assimilation of real-time observations. Model evaluations prior to the field program will

  12. Recent, unprecedented, arctic ozone losses: climate change or large interannual variability?

    NASA Astrophysics Data System (ADS)

    Rieder, H. E.; Polvani, L. M.

    2012-04-01

    The record ozone loss over the Arctic in the spring of 2011 [e.g., Manney et al., 2011] highlights the importance of a detailed understanding of the connection between cold polar temperatures, polar stratospheric clouds (PSCs) and column ozone. Several studies have analyzed the empirical relationship between PSC volume (Vpsc) and ozone loss in the Arctic [e.g., Rex et al., 2006], and put forward the hypothesis that the coldest Arctic winters are getting colder and therefore anomalous ozone losses in the Arctic are likely to increase in the coming decades. In the present study we analyze trends and variability in polar temperatures, Vpsc and column ozone, using both reanalysis products (ERA40, MERRA) and numerical model output (from selected models participating in the Chemistry-Climate Model Validation Activity). Beyond considering mean values, we employ a variety of statistical measures for extremes (i.e., high quantiles) in order to identify possible changes in the frequency distribution of polar temperatures and Vpsc, and attempt to determine whether the recent occurrences of record ozone loss are indicative of statistically significant trends or simply a reflection of large natural variability.

  13. Simulation of Climatic Changes in the Arctic and North Atlantic During Recent Decades

    NASA Technical Reports Server (NTRS)

    Hakkinen, Sirpa; Koblinsky, Chester J. (Technical Monitor)

    2001-01-01

    The interactions of the atmosphere and ice-ocean system in the Arctic will be studied using a coupled ice-ocean model which will also use ice drift derived from microwave observations as forcing. We especially search for linkages between the recent large climatic shifts in the Arctic Ocean and atmosphere for which period we also have microwave sea ice data. The coupled model area covers the whole N. Atlantic thus interactions between the lower latitudes are also investigated because we anticipate that the same large scale atmospheric patterns which dominate the midlatitudes extend their influence on the Arctic. The model hindcast for 1951-1993 shows clear decadal variability in the leading modes of ocean circulation. No specific low-freq modes are expected for the ice drift because its spectrum is white. However, the ice drift exhibits two see-saw patterns in response to the leading atmospheric circulation mode ('Arctic Oscillation'), one of them is the well-known out of phase relationship between Baffin Bay and Barents-Kara Seas, the other one is between Siberian shelf and Alaskan Coast (Hakkinen and Geiger, 2000).

  14. Simulation of the modern arctic climate by the NCAR CCM1

    NASA Technical Reports Server (NTRS)

    Bromwich, David H.; Tzeng, Ren-Yow; Parish, Thomas, R.

    1994-01-01

    The National Center of Atmospheric Research (NCAR) Community Climate Model Version 1 (CCM1's) simulation of the modern arctic climate is evaluated by comparing a five-year seasonal cycle simulation with the European Center for Medium-Range Weather Forecasts (ECMWF) global analyses. The sea level pressure (SLP), storm tracks, vertical cross section of height, 500-hPa height, total energy budget, and moisture budget are analyzed to investigate the biases in the simulated arctic climate. The results show that the model simulates anomalously low SLP, too much storm activity, and anomalously strong baroclinicity to the west of Greenland and vice versa to the east of Greenland. This bias is mainly attributed to the model's topographic representation of Greenland. First, the broadened Greenland topography in the model distorts the path of cyclone waves over the North Atlantic Ocean. Second, the model oversimulates the ridge over Greenland, which intensifies its blocking effect and steers the cyclone waves clockwise around it and hence produces an artificial circum-Greenland trough. These biases are significantly alleviated when the horizontal resolution increases to T42. Over the Arctic basin, the model simulates large amounts of low-level (stratus) clouds in winter and almost no stratus in summer, which is opposite to the observations. This bias is mainly due to the location of the simulated SLP features and the negative anomaly of storm activity, which prevent the transport of moisture into this region during summer but favor this transport in winter. The moisture budget analysis shows that the model's net annual precipitation (P-E) between 70 deg N and the North Pole is 6.6 times larger than the observations and the model transports six times more moisture into this region. The bias in the advection term is attributed to the positive moisture fixer scheme and the distorted flow pattern. However, the excessive moisture transport into the Arctic basin does not solely

  15. Climate impacts of shipping and petroleum extraction in an unlocked Arctic ocean

    NASA Astrophysics Data System (ADS)

    Samset, B. H.; Berntsen, T.; Dahlsøren, S. B.; Eide, L. I.; Eide, M. S.; Fuglestvedt, J.; Glomsrød, S.; Lindholt, L.; Myhre, G.; Nilssen, T. B.; Peters, G. P.; Ødemark, K.

    2012-04-01

    Reductions in sea ice extent are expected to open up the Arctic region to increased volumes of ship traffic and petroleum extraction activities. Both of these potentially entail changes in concentrations of short-lived climate forcers (SLCFs) such as aerosols and ozone, which may impact the future climate. The response of the Arctic to SLCF emissions is however not well constrained, as the annual cycle, solar irradiation, surface albedo and ambient temperature are special to this region. The present study investigates the effects of SLCF emissions in the Arctic in 2004, as well as in 2030 and 2050. An emission inventory is used for present day activities, while future emissions are taken from models of the global energy market and shipping fleet. Atmospheric concentrations are input to the OsloCTM2 chemical transport model, and radiative forcings (RFs) are calculated using a multi-stream radiation transport code. Climate impacts are quantified via RFs and Global Warming Potentials of the various emitted components, in addition to estimates of the first indirect aerosol effect and the snow albedo effect from black carbon (BC). For present day emissions we calculate a net negative RF from shipping, mainly driven by the indirect aerosol effect, and a net positive RF from petroleum extraction, mainly due to the BC snow albedo effect. For future emissions the general results remain similar, but the total RFs develop with changes in emission volume and composition. We discuss the sensitivity of the Arctic region to emissions in terms of normalized RFs as function of season and geographical location.

  16. Evolution of anomalies of salinity of surface waters of Arctic Ocean and their possible influence on climate changes

    NASA Astrophysics Data System (ADS)

    Popov, A.; Rubchenia, A.

    2009-04-01

    Numerous of model simulations of ice extent in Arctic Ocean predict almost full disappearance of sea ice in Arctic regions by 2050. However, the nature, as against models, does not suffer the unidirectional processes. By means of various feedback responses system aspires to come in an equilibrium condition. In Arctic regions one of the most powerful generators of a negative feedback is the fresh-water stream to Greenland Sea and Northern Atlantic. Increasing or decreasing of a fresh-water volume from the Arctic basin to Greenland Sea and Northern Atlantic results in significant changes in climatic system. At the Oceanology department of Arctic and Antarctic Research Institute (AARI) (St-Petersburg, Russia) in 2007, on the basis of the incorporated Russian-American database of the oceanographic data, reconstruction of long-term time series of average salinity of ocean surface was executed. The received time series describes the period from 1950 to 1993. For allocation of the processes determining formation of changes of average salinity of surface waters in Arctic basin the correlation analysis of interrelation of the received time series and several physical parameters which could affect formation of changes of salinity was executed. We found counter-intuitive result: formation of long-term changes of average salinity of surface waters of Arctic basin in the winter period does not depend on changes of a Siberian rivers runoff. Factors of correlation do not exceed -0,31. At the same time, clear inverse relationship of salinity of surface waters from volumes of the ice formed in flaw lead polynyas of the Siberian shelf seas is revealed. In this case factors of correlation change from -0,56 to -0,7. The maximum factor of correlation is -0,7. It characterizes interrelation of total volume of the ice formed in flaw lead polynyas of all seas of the Siberian shelf and average salinity of surface waters of Arctic basin. Thus, at increase of volumes of the ice formed in

  17. Accounts from 19th-century Canadian Arctic explorers' logs reflect present climate conditions

    NASA Astrophysics Data System (ADS)

    Overland, James E.; Wood, Kevin

    The widely perceived failure of 19th-century expeditions to find and transit the Northwest Passage in the Canadian Arctic is often attributed to extraordinary cold climatic conditions associated with the “Little Ice Age” evident in proxy records. However, examination of 44 explorers' logs for the western Arctic from 1818 to 1910 reveals that climate indicators such as navigability, the distribution and thickness of annual sea ice, monthly surface air temperature, and the onset of melt and freeze were within the present range of variability.The quest for the Northwest Passage through the Canadian archipelago during the 19th century is frequently seen as a vain and tragic failure. Polar exploration during the Victorian era seems to us today to have been a costly exercise in heroic futility, which in many respects it was. This perspective has been reinforced since the 1970s, when paleoclimate reconstructions based on Arctic ice core stratigraphy appeared to confirm the existence of exceptionally cold conditions consistent with the period glaciologists had termed the “Little Ice Age” (Figure 1a), with temperatures more than one standard deviation colder relative to an early 20th-century mean [Koerner, 1977; Koerner and Fisher, 1990; Overpeck et al., 1998]. In recent years, the view of the Little Ice Age as a synchronous worldwide and prolonged cold epoch that ended with modern warming has been questioned [Bradley and Jones, 1993; Jones and Briffa, 2001 ;Ogilvie, 2001].

  18. Arctic Spring Transition in Warming Climate: A Study Using Reanalysis Dataset

    NASA Astrophysics Data System (ADS)

    De, B.; Zhang, X.

    2014-12-01

    An increased warming trend over the Arctic in recent years has been documented using observations, and is expected to continue by climate model projections. This increase may shift the springtime transition time, resulting in a longer sea-ice melt and vegetation growing period over the Arctic. In this study, we investigated variability of and changes in the spring transition in a warming climate and examined attributions of various dynamic and thermodynamic processes. The results demonstrate a dramatic increase in springtime surface air temperature (SAT) over the Arctic since 1979. Physical analysis reveals the importance of large-scale poleward moisture and energy advection accompanied by an enhancement in net downward radiation flux, which result in the surface warming. The cloudiness could impact the surface radiation budget and retreat of sea ice cover reduces surface albedo, making an additional contribution to the surface warming. In addition to the overall evaluation of these physical processes, composite analysis suggests that relative contributions from these processes to the increased springtime SAT vary across different geographic sub-regions.

  19. Simulation of the modern arctic climate by the NCAR CCM1

    SciTech Connect

    Bromwich, D.H.; Tzeng, R.Y. ); Parish, T.R. )

    1994-07-01

    The NCAR CCM1's simulation of the modern arctic climate is evaluated by comparing a five-year seasonal cycle simulation with the ECMWF global analyses. The sea level pressure (SLP), storm tracks, vertical cross section of height, 500-hPa height, total energy budget, and moisture budget are analyzed to investigate the biases in the simulated arctic climate. The results show that the model simulates anomalously low SLP, too much activity, and anomalously strong baroclinicity to the west of Greenland and vice versa to the east of Greenland. This bias is mainly attributed to the model's topographic representation of Greenland. First, the broadened Greenland topography in the model distorts the path of cyclone waves over the North Atlantic Ocean. Second, the model oversimulates the ridge over Greenland, which intensifies its blocking effect and steers the cyclone waves clockwise around it and hence produces an artificial [open quotes]circum-Greenland[close quotes] trough. These biases are significantly alleviated when the horizontal resolution increases to T42. Over the Arctic basin, the modal simulates large amounts of low-level (stratus) clouds in winter and almost no stratus in summer, which is opposite to the observations. This bias is mainly due to the location of the simulated SLP features and the negative anomaly of storm activity, which prevent the transport of moisture into this region during summer but favor this transport in winter. 26 refs., 14 figs., 42 tabs.

  20. Marine Mammals and Climate Change in the Pacific Arctic: Impacts & Resilience

    NASA Astrophysics Data System (ADS)

    Moore, S. E.

    2014-12-01

    Extreme reductions in Arctic sea ice extent and thickness have become a hallmark of climate change, but impacts to the marine ecosystem are poorly understood. As top predators, marine mammals must adapt to biological responses to physical forcing and thereby become sentinels to ecosystem variability and reorganization. Recent sea ice retreats have influenced the ecology of marine mammals in the Pacific Arctic sector. Walruses now often haul out by the thousands along the NW Alaska coast in late summer, and reports of harbor porpoise, humpback, fin and minke whales in the Chukchi Sea demonstrate that these temperate species routinely occur there. In 2010, satellite tagged bowhead whales from Atlantic and Pacific populations met in the Northwest Passage, an overlap thought precluded by sea ice since the Holocene. To forage effectively, baleen whales must target dense patches of zooplankton and small fishes. In the Pacific Arctic, bowhead and gray whales appear to be responding to enhanced prey availability delivered both by new production and advection pathways. Two programs, the Distributed Biological Observatory (DBO) and the Synthesis of Arctic Research (SOAR), include tracking of marine mammal and prey species' responses to ecosystem shifts associated with sea ice loss. Both programs provide an integrated-ecosystem baseline in support of the development of a web-based Marine Mammal Health Map, envisioned as a component of the U.S. Integrated Ocean Observing System (IOOS). An overarching goal is to identify ecological patterns for marine mammals in the 'new' Arctic, as a foundation for integrative research, local response and adaptive management.

  1. How will the greening of the Arctic affect an important prey species and disturbance agent? Vegetation effects on arctic ground squirrels.

    PubMed

    Wheeler, H C; Chipperfield, J D; Roland, C; Svenning, J-C

    2015-07-01

    Increases in terrestrial primary productivity across the Arctic and northern alpine ecosystems are leading to altered vegetation composition and stature. Changes in vegetation stature may affect predator-prey interactions via changes in the prey's ability to detect predators, changes in predation pressure, predator identity and predator foraging strategy. Changes in productivity and vegetation composition may also affect herbivores via effects on forage availability and quality. We investigated if height-dependent effects of forage and non-forage vegetation determine burrowing extent and activity of arctic ground squirrels (Urocitellus parryii). We collected data on burrow networks and activity of arctic ground squirrels across long-term vegetation monitoring sites in Denali National Park and Preserve, Alaska. The implications of height-specific cover of potential forage and non-forage vegetation on burrowing behaviour and habitat suitability for arctic ground squirrels were investigated using hierarchical Bayesian modelling. Increased cover of forbs was associated with more burrows and burrow systems, and higher activity of systems, for all forb heights. No other potential forage functional group was related to burrow distribution and activity. In contrast, height-dependent negative effects of non-forage vegetation were observed, with cover over 50-cm height negatively affecting the number of burrows, systems and system activity. Our results demonstrate that increases in vegetation productivity have dual, potentially counteracting effects on arctic ground squirrels via changes in forage and vegetation stature. Importantly, increases in tall-growing woody vegetation (shrubs and trees) have clear negative effects, whereas increases in forb should benefit arctic ground squirrels. PMID:25666700

  2. Climate change and infectious diseases in the Arctic: establishment of a circumpolar working group.

    PubMed

    Parkinson, Alan J; Evengard, Birgitta; Semenza, Jan C; Ogden, Nicholas; Børresen, Malene L; Berner, Jim; Brubaker, Michael; Sjöstedt, Anders; Evander, Magnus; Hondula, David M; Menne, Bettina; Pshenichnaya, Natalia; Gounder, Prabhu; Larose, Tricia; Revich, Boris; Hueffer, Karsten; Albihn, Ann

    2014-01-01

    The Arctic, even more so than other parts of the world, has warmed substantially over the past few decades. Temperature and humidity influence the rate of development, survival and reproduction of pathogens and thus the incidence and prevalence of many infectious diseases. Higher temperatures may also allow infected host species to survive winters in larger numbers, increase the population size and expand their habitat range. The impact of these changes on human disease in the Arctic has not been fully evaluated. There is concern that climate change may shift the geographic and temporal distribution of a range of infectious diseases. Many infectious diseases are climate sensitive, where their emergence in a region is dependent on climate-related ecological changes. Most are zoonotic diseases, and can be spread between humans and animals by arthropod vectors, water, soil, wild or domestic animals. Potentially climate-sensitive zoonotic pathogens of circumpolar concern include Brucella spp., Toxoplasma gondii, Trichinella spp., Clostridium botulinum, Francisella tularensis, Borrelia burgdorferi, Bacillus anthracis, Echinococcus spp., Leptospira spp., Giardia spp., Cryptosporida spp., Coxiella burnetti, rabies virus, West Nile virus, Hantaviruses, and tick-borne encephalitis viruses. PMID:25317383

  3. Wave climate in the Arctic 1992-2014: seasonality and trends

    NASA Astrophysics Data System (ADS)

    Stopa, Justin E.; Ardhuin, Fabrice; Girard-Ardhuin, Fanny

    2016-07-01

    Over the past decade, the diminishing Arctic sea ice has impacted the wave field, which depends on the ice-free ocean and wind. This study characterizes the wave climate in the Arctic spanning 1992-2014 from a merged altimeter data set and a wave hindcast that uses CFSR winds and ice concentrations from satellites as input. The model performs well, verified by the altimeters, and is relatively consistent for climate studies. The wave seasonality and extremes are linked to the ice coverage, wind strength, and wind direction, creating distinct features in the wind seas and swells. The altimeters and model show that the reduction of sea ice coverage causes increasing wave heights instead of the wind. However, trends are convoluted by interannual climate oscillations like the North Atlantic Oscillation (NAO) and Pacific Decadal Oscillation. In the Nordic Greenland Sea the NAO influences the decreasing wind speeds and wave heights. Swells are becoming more prevalent and wind-sea steepness is declining. The satellite data show the sea ice minimum occurs later in fall when the wind speeds increase. This creates more favorable conditions for wave development. Therefore we expect the ice freeze-up in fall to be the most critical season in the Arctic and small changes in ice cover, wind speeds, and wave heights can have large impacts to the evolution of the sea ice throughout the year. It is inconclusive how important wave-ice processes are within the climate system, but selected events suggest the importance of waves within the marginal ice zone.

  4. Postglacial sea-level rise and its impact on the circum-arctic Holocene climate evolution

    NASA Astrophysics Data System (ADS)

    Bauch, Henning; Abramova, Ekaterina; Alenius, Teija; Saarnisto, Matti

    2016-04-01

    The global sea-level rise after the last glaciation not only affected the surface properties (circulation, T-S, sea ice seasonality) of the Arctic Ocean and nearby seas it also had a strong impact on the Holocene development of the shallow North Siberian shelf systems and the environmental evolution of the adjacent hinterland areas. In this region sea level reconstructions indicate the postglacial highstand occurred some time in the middle Holocene, between 6 to 5 ka (Klemann et al., 2015). After that time the sedimentary regime of the shelf seas stabilized as noted in a drastic decrease in sedimentation rates observed in all sediment cores taken from middle to outer shelf water depths of the Laptev Sea (Bauch et al. 2001). But, at water depths lower than 30 meters - i.e., in the inner shelf and nearer to the coasts - sedimentation continued at relatively higher rates, presumably due to input of terrigenous material from river runoff as well as coastal erosion. In relation to the latter process, the huge Lena Delta should comprise a region of sediment catchment where aggradation wins over erosion. However, little is known about the detailed history of this delta during the second half of the Holocene. We therefore have investigated three islands within the Lena Delta. All of these are comprised of massive peat of several meters in thickness. Picking discrete specimens of water mosses (Sphagnum) only, we have carefully dated these peat sections. The depth/age relation of the sampled profiles reflect the growth rate of peat, and thus, the islands. It shows that the islands' history above the present-day delta sea level is about 4000 yrs. old. Moreover, a significant change in peat growth is noted after 2500 yrs BP in both, accumulation and composition, and allows the conclusion of a major shift in Arctic environmental conditions since then. Thus, our results add further information also for other coastal studies, as the ongoing degradation of the rather vulnerable

  5. Long-term monitoring at multiple trophic levels suggests heterogeneity in responses to climate change in the Canadian Arctic tundra

    PubMed Central

    Gauthier, Gilles; Bêty, Joël; Cadieux, Marie-Christine; Legagneux, Pierre; Doiron, Madeleine; Chevallier, Clément; Lai, Sandra; Tarroux, Arnaud; Berteaux, Dominique

    2013-01-01

    Arctic wildlife is often presented as being highly at risk in the face of current climate warming. We use the long-term (up to 24 years) monitoring records available on Bylot Island in the Canadian Arctic to examine temporal trends in population attributes of several terrestrial vertebrates and in primary production. Despite a warming trend (e.g. cumulative annual thawing degree-days increased by 37% and snow-melt date advanced by 4–7 days over a 23-year period), we found little evidence for changes in the phenology, abundance or productivity of several vertebrate species (snow goose, foxes, lemmings, avian predators and one passerine). Only primary production showed a response to warming (annual above-ground biomass of wetland graminoids increased by 123% during this period). We nonetheless found evidence for potential mismatches between herbivores and their food plants in response to warming as snow geese adjusted their laying date by only 3.8 days on average for a change in snow-melt of 10 days, half of the corresponding adjustment shown by the timing of plant growth (7.1 days). We discuss several reasons (duration of time series, large annual variability, amplitude of observed climate change, nonlinear dynamic or constraints imposed by various rate of warming with latitude in migrants) to explain the lack of response by herbivores and predators to climate warming at our study site. We also show how length and intensity of monitoring could affect our ability to detect temporal trends and provide recommendations for future monitoring. PMID:23836788

  6. HOW WILL GLOBAL CLIMATE CHANGE AFFECT PARASITES?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    : Parasites are integral components of complex biotic assemblages that comprise the biosphere. Host switching correlated with episodic climate-change events are common in evolutionary and ecological time. Global climate change produces ecological perturbation, manifested in major geographical/pheno...

  7. Contaminant loading in remote Arctic lakes affects cellular stress-related proteins expression in feral charr.

    USGS Publications Warehouse

    Wiseman, Steve; Jorgensen, Even H.; Maule, Alec G.; Vijayan, Mathilakath M.

    2011-01-01

    The remote Arctic lakes on Bjornoya Island, Norway, offer a unique opportunity to study possible affect of lifelong contaminant exposure in wild populations of landlocked Arctic charr (Salvelinus alpinus). This is because Lake Ellasjoen has persistent organic pollutant (POP) levels that are significantly greater than in the nearby Lake Oyangen. We examined whether this differential contaminant loading was reflected in the expression of protein markers of exposure and effect in the native fish. We assessed the expressions of cellular stress markers, including cytochrome P4501A (Cyp1A), heat shock protein 70 (hsp70), and glucocorticoid receptor (GR) in feral charr from the two lakes. The average polychlorinated biphenyl (PCB) load in the charr liver from Ellasjoen was approximately 25-fold higher than in individuals from Oyangen. Liver Cyp1A protein expression was significantly higher in individuals from Ellasjoen compared with Oyangen, confirming differential PCB exposure. There was no significant difference in hsp70 protein expression in charr liver between the two lakes. However, brain hsp70 protein expression was significantly elevated in charr from Ellasjoen compared with Oyangen. Also, liver GR protein expression was significantly higher in the Ellasjoen charr compared with Oyangen charr. Taken together, our results suggest changes to cellular stress-related protein expression as a possible adaptation to chronic-contaminant exposure in feral charr in the Norwegian high-Arctic.

  8. Evaluating climate variables, indexes and thresholds governing Arctic urban sustainability: case study of Russian permafrost regions

    NASA Astrophysics Data System (ADS)

    Anisimov, O. A.; Kokorev, V.

    2013-12-01

    Addressing Arctic urban sustainability today forces planners to deal with the complex interplay of multiple factors, including governance and economic development, demography and migration, environmental changes and land use, changes in the ecosystems and their services, and climate change. While the latter can be seen as a factor that exacerbates the existing vulnerabilities to other stressors, changes in temperature, precipitation, snow, river and lake ice, and the hydrological regime also have direct implications for the cities in the North. Climate change leads to reduced demand for heating energy, on one hand, and heightened concerns about the fate of the infrastructure built upon thawing permafrost, on the other. Changes in snowfall are particularly important and have direct implications for the urban economy, as together with heating costs, expenses for snow removal from streets, airport runways, roofs and ventilation corridors underneath buildings erected on pile foundations on permafrost constitute the bulk of the city's maintenance budget. Many cities are located in river valleys and are prone to flooding that leads to enormous economic losses and casualties, including human deaths. The severity of the northern climate has direct implications for demographic changes governed by regional migration and labor flows. Climate could thus be viewed as an inexhaustible public resource that creates opportunities for sustainable urban development. Long-term trends show that climate as a resource is becoming more readily available in the Russian North, notwithstanding the general perception that globally climate change is one of the challenges facing humanity in the 21st century. In this study we explore the sustainability of the Arctic urban environment under changing climatic conditions. We identify key governing variables and indexes and study the thresholds beyond which changes in the governing climatic parameters have significant impact on the economy

  9. Large herbivore grazing affects the vegetation structure and greenhouse gas balance in a high arctic mire

    NASA Astrophysics Data System (ADS)

    Falk, Julie Maria; Schmidt, Niels Martin; Christensen, Torben R.; Ström, Lena

    2015-04-01

    Herbivory is an important part of most ecosystems and affects the ecosystems’ carbon balance both directly and indirectly. Little is known about herbivory and its impact on the carbon balance in high arctic mire ecosystems. We hypothesized that trampling and grazing by large herbivores influences the vegetation density and composition and thereby also the carbon balance. In 2010, we established fenced exclosures in high arctic Greenland to prevent muskoxen (Ovibos moschatus) from grazing. During the growing seasons of 2011 to 2013 we measured CO2 and CH4 fluxes in these ungrazed blocks and compared them to blocks subjected to natural grazing. Additionally, we measured depth of the water table and active layer, soil temperature, and in 2011 and 2013 an inventory of the vegetation density and composition were made. In 2013 a significant decrease in total number of vascular plant (33-44%) and Eriophorum scheuchzeri (51-53%) tillers were found in ungrazed plots, the moss-layer and amount of litter had also increased substantially in these plots. This resulted in a significant decrease in net ecosystem uptake of CO2 (47%) and likewise a decrease in CH4 emission (44%) in ungrazed plots in 2013. While the future of the muskoxen in a changing arctic is unknown, this experiment points to a potentially large effect of large herbivores on the carbon balance in natural Arctic ecosystems. It thus sheds light on the importance of grazing mammals, and hence adds to our understanding of natural ecosystem greenhouse gas balance in the past and in the future.

  10. Evaluation of climate model skill in representing upper Arctic Ocean hydrography for its potential effect on sea ice.

    NASA Astrophysics Data System (ADS)

    DiMaggio, D.; Maslowski, W.; Osinski, R.; Roberts, A.; Clement Kinney, J. L.

    2015-12-01

    The satellite derived rate of sea ice cover decline in the Arctic for the past decades is faster than those simulated by the latest suite of models participating in the Coupled Model Intercomparison Project (CMIP5), which is likely due to under-represented or missing high-latitude processes and feedbacks. We hypothesize that a critical source of energy in the Arctic Ocean, heat content accumulating below the surface mixed layer and above the Atlantic layer, has been increasing in magnitude and area, especially over the western Arctic marginal ice zone, and it may be contributing to the recent decline in the ice cover. Global and regional climate models must account for this heat content to more realistically simulate the altered regime of Arctic climate and its heat budget. We evaluate against observations results from the Regional Arctic System Model (RASM), including several model configurations, as well as output from other climate models to identify improvements needed to better represent upper Arctic Ocean hydrography and its impact on the sea ice cover.

  11. Atmospheric transport of persistent organic pollutants to and from the Arctic under present-day and future climate.

    PubMed

    Octaviani, Mega; Stemmler, Irene; Lammel, Gerhard; Graf, Hans F

    2015-03-17

    The long-term atmospheric cycling and fate of persistent organic pollutants under the influence of a changing climate is a concern. A GCM's realization of present-day (1970-1999) and future (2070-2099) climate, the latter under a medium scenario of greenhouse gas emissions, is used to study meridional transports and their correlations with the Arctic and North Atlantic Oscillations (AO and NAO). Regions of import and export maxima into the Arctic are identified along the Arctic Circle. It is found that, under future climate conditions, the net export of PCB153 out of the Arctic will increase. The meridional net flux pattern of this substance is expected to become independent of AO and NAO. For DDT, a trend of decreasing net Arctic import will reverse to an increasing trend 100 years after peak emission, which is partly due to more frequent AO and NAO positive phases. It is concluded that the long-term accumulation trends in the Arctic of other persistent pollutants, including so-called emerging pollutants, are subject to the substances' specific behavior and fate in the environment and need to be studied specifically. PMID:25686012

  12. The impact of Arctic sea ice on the Arctic energy budget and on the climate of the Northern mid-latitudes

    NASA Astrophysics Data System (ADS)

    Semmler, Tido; McGrath, Ray; Wang, Shiyu

    2012-12-01

    The atmospheric general circulation model EC-EARTH-IFS has been applied to investigate the influence of both a reduced and a removed Arctic sea ice cover on the Arctic energy budget and on the climate of the Northern mid-latitudes. Three 40-year simulations driven by original and modified ERA-40 sea surface temperatures and sea ice concentrations have been performed at T255L62 resolution, corresponding to 79 km horizontal resolution. Simulated changes between sensitivity and reference experiments are most pronounced over the Arctic itself where the reduced or removed sea ice leads to strongly increased upward heat and longwave radiation fluxes and precipitation in winter. In summer, the most pronounced change is the stronger absorption of shortwave radiation which is enhanced by optically thinner clouds. Averaged over the year and over the area north of 70° N, the negative energy imbalance at the top of the atmosphere decreases by about 10 W/m2 in both sensitivity experiments. The energy transport across 70° N is reduced. Changes are not restricted to the Arctic. Less extreme cold events and less precipitation are simulated in sub-Arctic and Northern mid-latitude regions in winter.

  13. Pirate attacks affect Indian Ocean climate research

    NASA Astrophysics Data System (ADS)

    Smith, Shawn R.; Bourassa, Mark A.; Long, Michael

    2011-07-01

    Pirate attacks in the Gulf of Aden and the Indian Ocean off the coast of Somalia nearly doubled from 111 in 2008 to 217 in 2009 [International Maritime Bureau, 2009, International Maritime Bureau, 2010]. Consequently, merchant vessel traffic in the area around Somalia significantly decreased. Many of these merchant vessels carry instruments that record wind and other weather conditions near the ocean surface, and alterations in ship tracks have resulted in a hole sized at about 2.5 million square kilometers in the marine weather-observing network off the coast of Somalia. The data void exists in the formation region of the Somali low-level jet, a wind pattern that is one of the main drivers of the Indian summer monsoon. Further, a stable, multidecadal record has been interrupted, and consequently, long-term analyses of the jet derived from surface wind data are now showing artificial anomalies that will affect efforts by scientists to identify interannual to decadal variations in the climate of the northwestern Indian Ocean.

  14. Factors affecting biotic mercury concentrations and biomagnification through lake food webs in the Canadian high Arctic.

    PubMed

    Lescord, Gretchen L; Kidd, Karen A; Kirk, Jane L; O'Driscoll, Nelson J; Wang, Xiaowa; Muir, Derek C G

    2015-03-15

    In temperate regions of Canada, mercury (Hg) concentrations in biota and the magnitude of Hg biomagnification through food webs vary between neighboring lakes and are related to water chemistry variables and physical lake features. However, few studies have examined factors affecting the variable Hg concentrations in landlocked Arctic char (Salvelinus alpinus) or the biomagnification of Hg through their food webs. We estimated the food web structure of six high Arctic lakes near Resolute Bay, Nunavut, Canada, using stable carbon (δ(13)C) and nitrogen (δ(15)N) isotopes and measured Hg (total Hg (THg) in char, the only fish species, and methylmercury (MeHg) in chironomids and zooplankton) concentrations in biota collected in 2010 and 2011. Across lakes, δ(13)C showed that benthic carbon (chironomids) was the dominant food source for char. Regression models of log Hg versus δ(15)N (of char and benthic invertebrates) showed positive and significant slopes, indicting Hg biomagnification in all lakes, and higher slopes in some lakes than others. However, no principal components (PC) generated using all water chemistry data and physical characteristics of the lakes predicted the different slopes. The PC dominated by aqueous ions was a negative predictor of MeHg concentrations in chironomids, suggesting that water chemistry affects Hg bioavailability and MeHg concentrations in these lower-trophic-level organisms. Furthermore, regression intercepts were predicted by the PCs dominated by catchment area, aqueous ions, and MeHg. Weaker relationships were also found between THg in small char or MeHg in pelagic invertebrates and the PCs dominated by catchment area, and aqueous nitrate and MeHg. Results from these high Arctic lakes suggest that Hg biomagnification differs between systems and that their physical and chemical characteristics affect Hg concentrations in lower-trophic-level biota. PMID:24909711

  15. Remote sensing of aerosols in the Arctic for an evaluation of global climate model simulations

    PubMed Central

    Glantz, Paul; Bourassa, Adam; Herber, Andreas; Iversen, Trond; Karlsson, Johannes; Kirkevåg, Alf; Maturilli, Marion; Seland, Øyvind; Stebel, Kerstin; Struthers, Hamish; Tesche, Matthias; Thomason, Larry

    2014-01-01

    In this study Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua retrievals of aerosol optical thickness (AOT) at 555 nm are compared to Sun photometer measurements from Svalbard for a period of 9 years. For the 642 daily coincident measurements that were obtained, MODIS AOT generally varies within the predicted uncertainty of the retrieval over ocean (ΔAOT = ±0.03 ± 0.05 · AOT). The results from the remote sensing have been used to examine the accuracy in estimates of aerosol optical properties in the Arctic, generated by global climate models and from in situ measurements at the Zeppelin station, Svalbard. AOT simulated with the Norwegian Earth System Model/Community Atmosphere Model version 4 Oslo global climate model does not reproduce the observed seasonal variability of the Arctic aerosol. The model overestimates clear-sky AOT by nearly a factor of 2 for the background summer season, while tending to underestimate the values in the spring season. Furthermore, large differences in all-sky AOT of up to 1 order of magnitude are found for the Coupled Model Intercomparison Project phase 5 model ensemble for the spring and summer seasons. Large differences between satellite/ground-based remote sensing of AOT and AOT estimated from dry and humidified scattering coefficients are found for the subarctic marine boundary layer in summer. Key Points Remote sensing of AOT is very useful in validation of climate models PMID:25821664

  16. Latitudinal distribution of the recent Arctic warming

    SciTech Connect

    Chylek, Petr; Lesins, Glen K; Wang, Muyin

    2010-12-08

    Increasing Arctic temperature, disappearance of Arctic sea ice, melting of the Greenland ice sheet, sea level rise, increasing strength of Atlantic hurricanes are these impending climate catastrophes supported by observations? Are the recent data really unprecedented during the observational records? Our analysis of Arctic temperature records shows that the Arctic and temperatures in the 1930s and 1940s were almost as high as they are today. We argue that the current warming of the Arctic region is affected more by the multi-decadal climate variability than by an increasing concentration of carbon dioxide. Unfortunately, none of the existing coupled Atmosphere-Ocean General Circulation Models used in the IPCC 2007 cIimate change assessment is able to reproduce neither the observed 20th century Arctic cIimate variability nor the latitudinal distribution of the warming.

  17. Arctic shelf flooding: a negative feedback on climate warming during terminations

    NASA Astrophysics Data System (ADS)

    Blaschek, Michael; Renssen, Hans

    2013-04-01

    heat release and surface warming during the entire year. Our analysis exhibits a surprising connection between increased sea-ice export through Fram Strait and changes in atmospheric winds that result from modifications in the atmospheric circulation, that are forced by changes in differential heating over the East Siberian Shelf and the Nordic Seas. This atmospheric teleconnection clearly shows that regional changes can affect hemispheric changes. In a first comparison with available sea-ice proxy reconstructions our results do not disagree, but show the necessity of increased temporal and spatial coverage of proxy reconstructions for future investigations. Our results indicate that shelf flooding had a significant impact on the climate during the early Holocene, namely reducing sea-ice cover and affecting atmospheric circulation. During terminations this can be considered to be a negative feedback on the progress of the termination, as a shelf area becomes flooded, sea-ice production and extent are likely to increase and reduce high latitude intake of orbitally-forced insolation, slowing down the warming trend. This can be the cause of observed cold reversals during warming phases in the continuous transformation of a glacial to an interglacial climate. This implies that shelf flooding should be taken into account when studying the climate dynamics during all glacial terminations. References Bauch, H.; Mueller-Lupp, T.; Taldenkova, E.; Spielhagen, R.; Kassens, H.; Grootes, P.; Thiede, J.; Heinemeier, J. & Petryashov, V. Chronology of the Holocene transgression at the North Siberian margin, Global and Planetary Change, 2001, 31, 125 - 139 Rigor, I. & Colony, R., Sea-ice production and transport of pollutants in the Laptev Sea, 1979-1993, Science of The Total Environment, Environmental Radioactivity in the Arctic, 1997, 202, 89-110 Tamura, T. & Ohshima, K. I., Mapping of sea ice production in the Arctic coastal polynyas, J. Geophys. Res., AGU, 2011, 116, C07030-

  18. The Arctic Holocene Transitions Proxy Climate Database — Principal Millennial-Scale Patterns

    NASA Astrophysics Data System (ADS)

    Kaufman, D. S.; McKay, N.

    2014-12-01

    The Arctic Holocene Transitions (AHT) Project is a community-based, PAGES-endorsed effort to investigate centennial-scale variability in the Arctic climate system during the Holocene, and to understand the feedbacks that lead to pronounced changes. The AHT project recently released a major database of Arctic Holocene proxy climate records (Clim. Past-Disc. 10:1). The systematic review of marine and terrestrial proxy climate time series is based on quantitative screening criteria with new approaches for assessing the geochronological accuracy of age models and for characterizing the climate variables represented by the proxies. Records from only 39% of the sites could be found in the primary paleoclimate data repositories, underscoring the importance of such community-based efforts to assembling a comprehensive product. The database authors, including representatives from six Arctic regions, considered published records from nearly 500 sites. Of these, time series from 170 sites met the criteria for inclusion in the database. Namely, the records are located north of 58°N, extend back at least to 6 cal ka (84% extend back > 8 ka), are resolved at sub-millennial scale (at least one value every 400 ± 200 yr) and have age models constrained by at least one age every 3000 yr. The database contains proxy records from lake sediment (60%), marine sediment (32%), glacier ice (5%), and other sources. Most (60%) reflect temperature (mainly summer warmth) and are primarily based on pollen, chironomid or diatom assemblages. Many (15%) reflect some aspect of hydroclimate as inferred from stable isotopes, pollen assemblages, and other indicators. Principal component (PC) analyses indicates that the predominant pattern of change in temperature-sensitive time series is a ramp between 5 and 3 ka that separates millennial-long intervals of less-pronounced change. This shift corresponds to cooling at most sites, but a substantial fraction of sites warm across this transition. Between

  19. Identifying the main drivers of soil carbon response to climate change in arctic and boreal Alaska.

    NASA Astrophysics Data System (ADS)

    Genet, H.; McGuire, A. D.; He, Y.; Johnson, K.; Wylie, B. K.; Pastick, N. J.; Zhuang, Q.; Zhu, Z.

    2015-12-01

    Boreal and arctic regions represent the largest reservoir of carbon among terrestrial biomes. Most of this carbon is stored deep in the soil in permafrost where frozen organic matter is protected from decomposition. The vulnerability of soil carbon stocks to a changing climate in high latitudes depends on a number of physical and ecological processes. The importance of these processes in controlling the dynamics of soil carbon stocks vary across regions because of variability in vegetation composition, drainage condition, and permafrost characteristics. To better understand the main drivers of the vulnerability of soil carbon stocks to climate change in Alaska, we ran a process-based ecosystem model, the Terrestrial Ecosystem Model. This model explicitly simulates interactions between the carbon cycle and permafrost dynamics and was coupled with a disturbance model and a model of biogenic methane dynamics to assess historical and projected soil carbon dynamics in Alaska, from 1950 to 2100. The uncertainties related to climate, fire regime and atmospheric CO2projections on soil carbon dynamics were quantified by running simulations using climate projections from 2 global circulation models, 3 fossil fuel emission scenarios and 3 alternative fire management scenarios. During the historical period [1950-2009], soil carbon stocks increased by 4.7 TgC/yr in Alaska. Soil carbon stocks decreased in boreal Alaska due to substantial fire activity in the early 2000's. This loss was offset by carbon accumulation in the arctic. Changes in soil carbon stocks from 2010 to 2099 ranged from 8.9 to 25.6 TgC/yr, depending on the climate projections. Soil carbon accumulation was slower in lowlands than in uplands and slower in the boreal than in the arctic regions because of the negative effect of fire activity on soil carbon stocks. Tundra ecosystems were more vulnerable to carbon loss from fire than forest ecosystems because of a lower productivity. As a result, the increase in

  20. Wildfires in northern Eurasia affect the budget of black carbon in the Arctic - a 12-year retrospective synopsis (2002-2013)

    NASA Astrophysics Data System (ADS)

    Evangeliou, N.; Balkanski, Y.; Hao, W. M.; Petkov, A.; Silverstein, R. P.; Corley, R.; Nordgren, B. L.; Urbanski, S. P.; Eckhardt, S.; Stohl, A.; Tunved, P.; Crepinsek, S.; Jefferson, A.; Sharma, S.; Nøjgaard, J. K.; Skov, H.

    2016-06-01

    In recent decades much attention has been given to the Arctic environment, where climate change is happening rapidly. Black carbon (BC) has been shown to be a major component of Arctic pollution that also affects the radiative balance. In the present study, we focused on how vegetation fires that occurred in northern Eurasia during the period of 2002-2013 influenced the budget of BC in the Arctic. For simulating the transport of fire emissions from northern Eurasia to the Arctic, we adopted BC fire emission estimates developed independently by GFED3 (Global Fire Emissions Database) and FEI-NE (Fire Emission Inventory - northern Eurasia). Both datasets were based on fire locations and burned areas detected by MODIS (Moderate resolution Imaging Spectroradiometer) instruments on NASA's (National Aeronautics and Space Administration) Terra and Aqua satellites. Anthropogenic sources of BC were adopted from the MACCity (Monitoring Atmospheric Composition and Climate and megacity Zoom for the Environment) emission inventory.During the 12-year period, an average area of 250 000 km2 yr-1 was burned in northern Eurasia (FEI-NE) and the global emissions of BC ranged between 8.0 and 9.5 Tg yr-1 (FEI-NE+MACCity). For the BC emitted in the Northern Hemisphere (based on FEI-NE+MACCity), about 70 % originated from anthropogenic sources and the rest from biomass burning (BB). Using the FEI-NE+MACCity inventory, we found that 102 ± 29 kt yr-1 BC was deposited in the Arctic (defined here as the area north of 67° N) during the 12 years simulated, which was twice as much as when using the MACCity inventory (56 ± 8 kt yr-1). The annual mass of BC deposited in the Arctic from all sources (FEI-NE in northern Eurasia, MACCity elsewhere) is significantly higher by about 37 % in 2009 (78 vs. 57 kt yr-1) to 181 % in 2012 (153 vs. 54 kt yr-1), compared to the BC deposited using just the MACCity emission inventory. Deposition of BC in the Arctic from BB sources in the Northern Hemisphere

  1. The climate of the Taimyr Peninsula in the Holocene and a Forecast of Climatic Changes in the Arctic

    NASA Astrophysics Data System (ADS)

    Ukraintseva, V.

    2009-04-01

    Based on the data of the spore-pollen and radiocarbon methods during our research of a peat bog in the south-eastern part of the Taimyr Peninsula we discovered for the first time the natural dynamics of the climate for this region during the period of the last 10 500 years [2, 3] and made a long-term forecast of climatic changes both for the Taimyr Peninsula and for other Arctic regions. By the quantitative characteristics of the climate and their dynamics in time, reconstructed for the basin of the Fomich River (71 ° 42 ' North, 108 ° 03 ' East) and for the Taimyr Peninsula on the whole, we have established two climatic types: tundra (10500 ±140 years BP- 7040 ± 60 years BP) and forest (5720± 60 years BP - 500 ± 60 years BP to the present time). In the first half of the Holocene the climate there was rather stable; only 7530 years ago a sharp cooling took place; the second half of the Holocene, beginning with 5720 years ago, is characterized by alternating fluctuations in the climate [3]. Taking only the palaeoclimatic reconstructions as a basis, we can talk about a trend of climatic changes in the future. However comparing the Sun activity` forecast, expressed in Wolf units (Max W), made by V.N. Kupetsky [1], with the climatic characteristics, which we have reconstructed, we could then make a more precise forecast of climatic changes for the Taimyr Peninsula and the Russian part of the Arctic (Table). The above forecast lets us make the following basically important conclusions: (1) the climate`s warming, which is currently being observed on the Earth (the 23rd cycle of the Sun`s activity) will last till 2011; (2) during the following two cycles (24th and 25th) the Sun`s activity will decrease to 100-110 Wolf units, which will cause a cooling of the climate on the Earth; (3) in the following, the 26th cycle, the Sun`s activity will increase up to 130 Wolf units, which will cause a warming of the climate; (4) in the 27th cycle (2037-2048) the Sun`s activity

  2. Microbial Functional Potential and Community Composition in Permafrost-Affected Soils of the NW Canadian Arctic

    PubMed Central

    Frank-Fahle, Béatrice A.; Yergeau, Étienne; Greer, Charles W.; Lantuit, Hugues; Wagner, Dirk

    2014-01-01

    Permafrost-affected soils are among the most obvious ecosystems in which current microbial controls on organic matter decomposition are changing as a result of global warming. Warmer conditions in polygonal tundra will lead to a deepening of the seasonal active layer, provoking changes in microbial processes and possibly resulting in exacerbated carbon degradation under increasing anoxic conditions. To identify current microbial assemblages in carbon rich, water saturated permafrost environments, four polygonal tundra sites were investigated on Herschel Island and the Yukon Coast, Western Canadian Arctic. Ion Torrent sequencing of bacterial and archaeal 16S rRNA amplicons revealed the presence of all major microbial soil groups and indicated a local, vertical heterogeneity of the polygonal tundra soil community with increasing depth. Microbial diversity was found to be highest in the surface layers, decreasing towards the permafrost table. Quantitative PCR analysis of functional genes involved in carbon and nitrogen-cycling revealed a high functional potential in the surface layers, decreasing with increasing active layer depth. We observed that soil properties driving microbial diversity and functional potential varied in each study site. These results highlight the small-scale heterogeneity of geomorphologically comparable sites, greatly restricting generalizations about the fate of permafrost-affected environments in a warming Arctic. PMID:24416279

  3. Impact of climate change on zooplankton communities, seabird populations and arctic terrestrial ecosystem—A scenario

    NASA Astrophysics Data System (ADS)

    Stempniewicz, Lech; Błachowiak-Samołyk, Katarzyna; Węsławski, Jan M.

    2007-11-01

    Many arctic terrestrial ecosystems suffer from a permanent deficiency of nutrients. Marine birds that forage at sea and breed on land can transport organic matter from the sea to land, and thus help to initiate and sustain terrestrial ecosystems. This organic matter initiates the emergence of local tundra communities, increasing primary and secondary production and species diversity. Climate change will influence ocean circulation and the hydrologic regime, which will consequently lead to a restructuring of zooplankton communities between cold arctic waters, with a dominance of large zooplankton species, and Atlantic waters in which small species predominate. The dominance of large zooplankton favours plankton-eating seabirds, such as the little auk ( Alle alle), while the presence of small zooplankton redirects the food chain to plankton-eating fish, up through to fish-eating birds (e.g., guillemots Uria sp.). Thus, in regions where the two water masses compete for dominance, such as in the Barents Sea, plankton-eating birds should dominate the avifauna in cold periods and recess in warmer periods, when fish-eaters should prevail. Therefore under future anthropogenic climate scenarios, there could be serious consequences for the structure and functioning of the terrestrial part of arctic ecosystems, due in part to changes in the arctic marine avifauna. Large colonies of plankton-eating little auks are located on mild mountain slopes, usually a few kilometres from the shore, whereas colonies of fish-eating guillemots are situated on rocky cliffs at the coast. The impact of guillemots on the terrestrial ecosystems is therefore much smaller than for little auks because of the rapid washing-out to sea of the guano deposited on the seabird cliffs. These characteristics of seabird nesting sites dramatically limit the range of occurrence of ornithogenic soils, and the accompanying flora and fauna, to locations where talus-breeding species occur. As a result of climate

  4. Inter-model diversity in jet stream changes and its relation to Arctic climate in CMIP5

    NASA Astrophysics Data System (ADS)

    Yim, Bo Young; Min, Hong Sik; Kug, Jong-Seong

    2016-07-01

    We examined how coupled general circulation models (CGCMs) simulate changes in the jet stream differently under greenhouse warming, and how this inter-model diversity is related to the simulated Arctic climate changes by analyzing the simulation of the Coupled Model Intercomparison Project Phase 5. Although the jet stream in the multi-model ensemble mean shifts poleward, a considerable diversity exists among the 34 CGCMs. We found that inter-model differences in zonal wind responses, especially in terms of meridional shift of the midlatitude jet, are highly dependent on Arctic surface warming and lower stratospheric cooling. Specifically, the midlatitude jet tends to shift relatively equatorward (poleward) in the models with stronger (weaker) Arctic surface warming, whereas the jet tends to shift relatively poleward (equatorward) in the models with stronger (weaker) Arctic lower stratospheric cooling.

  5. Climatic interpretation of Paleogene and Early Neogene spore-pollen floras from Spitsbergen and Arctic Canada

    SciTech Connect

    Norris, G.; Head, M.J.

    1985-01-01

    A relatively complete spore-pollen record through the Late Paleocene and possible Early Eocene from Spitsbergen (lat. 78/sup 0/C long 15/sup 0/E) comprises assemblages commonly with a high conifer and fern content and with moderate triporate angiosperm values. Assemblages are notably dissimilar from those at mid-latitudes and include a number of species which do not appear in Europe until Oligocene or earlier times. This all suggests that the climate varied within a temperate regime. Conifer and fern spores remain abundant but angiosperm pollen is much more diverse and includes taxa referable to Ulmus, Alnus, Juglans, Liquidambar, Pterocarya, Tilia, Fagus, Nyssa, Ilex, .Nuphar, and the Onagraceae which collectively indicate a moderately warm temperate climate. These assemblages thus predate putative Oligocene cooling and fix a maximum possible age limit for its initiation in this area. Eocene floras of the eastern Canadian Arctic (80/sup 0/N, 100/sup 0/W) have been interpreted as sub-tropical but may be warm temperate. Late Eocene spore-pollen assemblages from the Beaufort-Mackenzie Basin of western Arctic Canada (l at 69/sup 0/N, long 134/sup 0/W) are similar to those from Spitsbergen. Species diversity decreases near the Eocene/Oligocene boundary notably related to disappearance of thermophylic taxa indicating cooling for at least part of the Early and Middle Oligocene interval. Warm temperate or temperate floras were reestablished in the Late Oligocene and Miocene of Arctic Canada but were replaced by boreal tundra floras in the Pliocene at latest.

  6. Regional Arctic sea ice variations as predictor for winter climate conditions

    NASA Astrophysics Data System (ADS)

    Koenigk, Torben; Caian, Mihaela; Nikulin, Grigory; Schimanke, Semjon

    2016-01-01

    Seasonal prediction skill of winter mid and high northern latitudes climate from sea ice variations in eight different Arctic regions is analyzed using detrended ERA-interim data and satellite sea ice data for the period 1980-2013. We find significant correlations between ice areas in both September and November and winter sea level pressure, air temperature and precipitation. The prediction skill is improved when using November sea ice conditions as predictor compared to September. This is particularly true for predicting winter NAO-like patterns and blocking situations in the Euro-Atlantic area. We find that sea ice variations in Barents Sea seem to be most important for the sign of the following winter NAO—negative after low ice—but amplitude and extension of the patterns are modulated by Greenland and Labrador Seas ice areas. November ice variability in the Greenland Sea provides the best prediction skill for central and western European temperature and ice variations in the Laptev/East Siberian Seas have the largest impact on the blocking number in the Euro-Atlantic region. Over North America, prediction skill is largest using September ice areas from the Pacific Arctic sector as predictor. Composite analyses of high and low regional autumn ice conditions reveal that the atmospheric response is not entirely linear suggesting changing predictive skill dependent on sign and amplitude of the anomaly. The results confirm the importance of realistic sea ice initial conditions for seasonal forecasts. However, correlations do seldom exceed 0.6 indicating that Arctic sea ice variations can only explain a part of winter climate variations in northern mid and high latitudes.

  7. Nye Lecture: Snow Crystals, Shrubs, and the Changing Climate of the Arctic

    NASA Astrophysics Data System (ADS)

    Sturm, M.

    2005-12-01

    At the peak of winter, snow covers more than 45 million km2 of the northern hemisphere. More than 90 percent of this snow will melt before the end of the following summer. In the southern part of this snow-covered area, the seasonal pack is ephemeral, lasting but a few short weeks, but with increasing latitude (or altitude), it lasts much longer. In arctic and alpine locations it can persist for 9 months of the year. In these more extreme locations, the snow is an essential element of the ecosystem, both acting upon, and being acted on, by the biota. For historical reasons, our understanding of snow cover and its interactions has come from two disparate scientific sources: geophysicists working on glaciers and avalanches who were trying to understand snow properties and to develop a physical basis for snow science, and ecologists who were trying to understand the impact of snow on plants, animals, and humans. With the recognition now that snow is both a passive and active agent, we are seeing an increasing number of studies wherein both of these traditional approaches are combined. Geophysicists are learning the Latin names of shrubs while botanist can now identify wind slab. A personal example that illustrates the necessity of this melding process has been our effort to understand the climatic implications of Arctic snow-shrub interactions. We have had to combine traditional snow geophysical studies (i.e., crystal growth, thermal processes, light reflection) with traditional ecological studies (i.e., competition, carbon and nitrogen cycling). Through this process we have discovered that snow-shrub interactions, or more broadly, snow-vegetation interactions, are helping to push the Arctic down a warming trajectory that has global implications. Soil microbes and snow crystals, wind-blown snow and shrubs, are all leading actors in a climate change drama whose outcome is of concern to us all.

  8. How is climate warming altering the carbon cycle of a tundra ecosystem in the Siberian Arctic?

    NASA Astrophysics Data System (ADS)

    Belelli Marchesini, Luca; (Ko) van Huissteden, Jacobus; van der Molen, Michiel; Parmentier, Frans-Jan W.; Maximov, Trofim; Budishchev, Artem; Gallagher, Angela; (Han) Dolman, Albertus J.

    2015-04-01

    Climate has been warming over the the Arctic region with the strongest anomalies taking place in autumn and winter for the period 2000-2010, particularly in northern Eurasia. The quantification of the impact on climate warming on the degradation of permafrost and the associated potential release to the atmosphere of carbon stocked in the soil under the form of greenhouse gases, thus further increasing the radiative forcing of the atmosphere, is currently a matter of scientific debate. The positive trend in primary productivity in the last decades inferred by vegetation indexes (NDVI) and confirmed by observations on the enhanced growth of shrub vegetation represents indeed a contrasting process that, if prevalent could offset GHG emissions or even strengthen the carbon sink over the Arctic tundra. At the site of Kytalyk, in north-eastern Siberia, net fluxes of CO2 at ecosystem scale (NEE) have been monitored by eddy covariance technique since 2003. While presenting the results of the seasonal (snow free period) and inter-annual variability of NEE, conceived as the interplay between meteorological drivers and ecosystem responses, we test the role of climate as the main source of NEE variability in the last decade using a data oriented statistical approach. The impact of the timing and duration of the snow free period on the seasonal carbon budget is also considered. Finally, by including the results of continuous micrometeorological observations of methane fluxes taken during summer 2012, corroborated with seasonal CH4 budgets from two previous shorter campaigns (2008, 2009), as well as an experimentally determined estimate of dissolved organic carbon (DOC) flux, we provide an assessment of the carbon budget and its stability over time. The examined tundra ecosystem was found to sequester CO2 during the snow free season with relatively small inter-annual variability (-97.9±12.1gC m-2) during the last decade and without any evident trend despite the carbon uptake

  9. The Arctic Climate Modeling Program: K-12 Geoscience Professional Development for Rural Educators

    NASA Astrophysics Data System (ADS)

    Bertram, K. B.

    2009-12-01

    Helping teachers and students connect with scientists is the heart of the Arctic Climate Modeling Program (ACMP), funded from 2005-09 by the National Science Foundation’s Innovative Technology Experience for Students and Teachers. ACMP offered progressive yearlong science, technology and math (STM) professional development that prepared teachers to train youth in workforce technologies used in Arctic research. ACMP was created for the Bering Strait School District, a geographically isolated area with low standardized test scores, high dropout rates, and poverty. Scientists from around the globe have converged in this region and other areas of the Arctic to observe and measure changes in climate that are significant, accelerating, and unlike any in recorded history. Climate literacy (the ability to understand Earth system science and to make scientifically informed decisions about climate changes) has become essential for this population. Program resources were designed in collaboration with scientists to mimic the processes used to study Arctic climate. Because the Bering Strait School District serves a 98 percent Alaska Native student population, ACMP focused on best practices shown to increase the success of minority students. Significant research indicates that Alaska Native students succeed academically at higher rates when instruction addresses topics of local interest, links education to the students’ physical and cultural environment, uses local knowledge and culture in the curriculum, and incorporates hands-on, inquiry-based lessons in the classroom. A seven-partner consortium of research institutes and Alaska Native corporations created ACMP to help teachers understand their role in nurturing STM talent and motivating students to explore geoscience careers. Research underscores the importance of increasing school emphasis in content areas, such as climate, that facilitate global awareness and civic responsibility, and that foster critical thinking and

  10. Climate change and water security with a focus on the Arctic.

    PubMed

    Evengard, Birgitta; Berner, Jim; Brubaker, Michael; Mulvad, Gert; Revich, Boris

    2011-01-01

    Water is of fundamental importance for human life; access to water of good quality is of vital concern for mankind. Currently however, the situation is under severe pressure due to several stressors that have a clear impact on access to water. In the Arctic, climate change is having an impact on water availability by melting glaciers, decreasing seasonal rates of precipitation, increasing evapotranspiration, and drying lakes and rivers existing in permafrost grounds. Water quality is also being impacted as manmade pollutants stored in the environment are released, lowland areas are flooded with salty ocean water during storms, turbidity from permafrost-driven thaw and erosion is increased, and the growth or emergence of natural pollutants are increased. By 2030 it is estimated that the world will need to produce 50% more food and energy which means a continuous increase in demand for water. Decisionmakers will have to very clearly include life quality aspects of future generations in the work as impact of ongoing changes will be noticeable, in many cases, in the future. This article will focus on effects of climate-change on water security with an Arctic perspective giving some examples from different countries how arising problems are being addressed. PMID:22043217

  11. Strong atmospheric chemistry feedback to climate warming from Arctic methane emissions

    USGS Publications Warehouse

    Isaksen, Ivar S.A.; Gauss, Michael; Myhre, Gunnar; Walter Anthony, Katey M.; Ruppel, Carolyn

    2011-01-01

    The magnitude and feedbacks of future methane release from the Arctic region are unknown. Despite limited documentation of potential future releases associated with thawing permafrost and degassing methane hydrates, the large potential for future methane releases calls for improved understanding of the interaction of a changing climate with processes in the Arctic and chemical feedbacks in the atmosphere. Here we apply a “state of the art” atmospheric chemistry transport model to show that large emissions of CH4 would likely have an unexpectedly large impact on the chemical composition of the atmosphere and on radiative forcing (RF). The indirect contribution to RF of additional methane emission is particularly important. It is shown that if global methane emissions were to increase by factors of 2.5 and 5.2 above current emissions, the indirect contributions to RF would be about 250% and 400%, respectively, of the RF that can be attributed to directly emitted methane alone. Assuming several hypothetical scenarios of CH4 release associated with permafrost thaw, shallow marine hydrate degassing, and submarine landslides, we find a strong positive feedback on RF through atmospheric chemistry. In particular, the impact of CH4 is enhanced through increase of its lifetime, and of atmospheric abundances of ozone, stratospheric water vapor, and CO2 as a result of atmospheric chemical processes. Despite uncertainties in emission scenarios, our results provide a better understanding of the feedbacks in the atmospheric chemistry that would amplify climate warming.

  12. Climate change and water security with a focus on the Arctic

    PubMed Central

    Evengard, Birgitta; Berner, Jim; Brubaker, Michael; Mulvad, Gert; Revich, Boris

    2011-01-01

    Water is of fundamental importance for human life; access to water of good quality is of vital concern for mankind. Currently however, the situation is under severe pressure due to several stressors that have a clear impact on access to water. In the Arctic, climate change is having an impact on water availability by melting glaciers, decreasing seasonal rates of precipitation, increasing evapotranspiration, and drying lakes and rivers existing in permafrost grounds. Water quality is also being impacted as manmade pollutants stored in the environment are released, lowland areas are flooded with salty ocean water during storms, turbidity from permafrost-driven thaw and erosion is increased, and the growth or emergence of natural pollutants are increased. By 2030 it is estimated that the world will need to produce 50% more food and energy which means a continuous increase in demand for water. Decisionmakers will have to very clearly include life quality aspects of future generations in the work as impact of ongoing changes will be noticeable, in many cases, in the future. This article will focus on effects of climate-change on water security with an Arctic perspective giving some examples from different countries how arising problems are being addressed. PMID:22043217

  13. Potential impacts of climate change on infectious diseases in the Arctic.

    PubMed

    Parkinson, Alan J; Butler, Jay C

    2005-12-01

    Climate change could cause changes in the incidence of infectious diseases in Arctic regions. Higher ambient temperatures in the Arctic may result in an increase in some temperature sensitive foodborne diseases such as gastroenteritis, paralytic shellfish poisoning and botulism. An increase in mean temperature may also influence the incidence of infectious diseases of animals that are spread to humans (zoonoses) by changing the population and range of animal hosts and insect vectors. An increase in flooding events may result in outbreaks of waterborne infection, such as Giardia lamblia or Cryptospordium parvum. A change in rodent and fox populations may result in an increase in rabies or echinococcosis. Temperature and humidity influence the distribution and density of many arthropod vectors which in turn may influence the incidence and northern range of vectorborne diseases such as West Nile virus. Recommendations include: the strenghtening of public health systems, disease surveillance coordinated with climate monitoring, and research into the detection, prevention, control and treatment of temperature-sensitive infectious diseases. PMID:16440610

  14. Building Partnerships and Research Collaborations to Address the Impacts of Arctic Change: The North Atlantic Climate Change Collaboration (NAC3)

    NASA Astrophysics Data System (ADS)

    Polk, J.; North, L. A.; Strenecky, B.

    2015-12-01

    Changes in Arctic warming influence the various atmospheric and oceanic patterns that drive Caribbean and mid-latitude climate events, including extreme events like drought, tornadoes, and flooding in Kentucky and the surrounding region. Recently, the establishment of the North Atlantic Climate Change Collaboration (NAC3) project at Western Kentucky University (WKU) in partnership with the University of Akureyri (UNAK), Iceland Arctic Cooperation Network (IACN), and Caribbean Community Climate Change Centre (CCCCC) provides a foundation from which to engage students in applied research from the local to global levels and more clearly understand the many tenets of climate change impacts in the Arctic within both a global and local community context. The NAC3 project encompasses many facets, including joint international courses, student internships, economic development, service learning, and applied research. In its first phase, the project has generated myriad outcomes and opportunities for bridging STEM disciplines with other fields to holistically and collaboratively address specific human-environmental issues falling under the broad umbrella of climate change. WKU and UNAK students desire interaction and exposure to other cultures and regions that are threatened by climate change and Iceland presents a unique opportunity to study influences such as oceanic processes, island economies, sustainable harvest of fisheries, and Arctic influences on climate change. The project aims to develop a model to bring partners together to conduct applied research on the complex subject of global environmental change, particularly in the Arctic, while simultaneously focusing on changing how we learn, develop community, and engage internationally to understand the impacts and find solutions.

  15. Remote sensing aides studies of climate and wildlife in the Arctic-on land, at sea, and in the air (Invited)

    NASA Astrophysics Data System (ADS)

    Douglas, D. C.; Durner, G. M.; Gill, R. E.; Griffith, B.; Schmutz, J. A.

    2013-12-01

    Every day a variety of remote sensing technologies collects large volumes of data that are supporting new analyses and new interpretations about how weather and climate influence the status and distribution of wildlife populations worldwide. Understanding how climate presently affects wildlife is crucial for projecting how climate change could affect wildlife in the future. This talk highlights climate-related wildlife studies by the US Geological Survey in the Arctic. The Arctic is experiencing some of the most pronounced climate changes on earth, raising concerns for species that have evolved seasonal migration strategies tuned to habitat availability and quality. On land, large herbivores such as caribou select concentrated calving areas with high abundance of rapidly growing vegetation and calf survival increases with earlier green-up and with the quantity of food available to cows at peak lactation. Geese time their migrations and reproductive efforts to coincide with optimal plant phenology and peak nutrient availability and departures from this synchrony can influence the survival of goslings. At sea, the habitats of polar bears and other sea-ice-dependent species have dramatically changed over just the past two decades. The ice pack is comprised of younger ice that melts much more extensively during summer-a trend projected to continue by all general circulation models under all but the most aggressive greenhouse gas mitigation scenarios. Studies show that by mid-century optimal polar bear habitats will be so reduced that the species may become extirpated from some regions of the Arctic. In the air, a variety of shorebird species make non-stop endurance flights between northern and southern hemispheres. The bar-tailed godwit undertakes a trans-Pacific flight between Alaska and Australasia that lasts more than seven days and spans more than 10,000 km. Studies show that godwits time their flights to coincide with favorable wind conditions, but stochastic

  16. Potential NEE Budget and Prediction of Future Emissions under Climate Change in an Arctic Wet Sedge Tundra, Barrow, Alaska .

    NASA Astrophysics Data System (ADS)

    Kalhori, A. A. M.; Oechel, W. C.; Burba, G. G.; Gioli, B.; Zona, D.; Murphy, P.; Goodrich, J. P.

    2015-12-01

    Arctic ecosystems are critically affected by climate change and also play an important role in the global carbon budget. Presented here is a 14-year study of growing season CO2 fluxes in an Alaskan wet sedge tundra ecosystem -which is about 2 km south of the Arctic Ocean and is adjacent to the NOAA Climate Monitoring & Diagnostic Laboratory (CMDL)- and the key environmental controls on these fluxes. We have measured net ecosystem exchange of CO2 (NEE) using the eddy covariance technique from 1998 to 2014 in order to quantify the long-term seasonal and inter-annual variability in the CO2 budget over this period. The WPL correction and the surface heating correction were applied to all CO2 flux data from the open-path instrument (Burba et al., 2008). Despite several gaps in measurement years, we found that growing season net CO2 uptake has significantly increased since the 2000s and that NEE is sensitive to dry conditions in tundra. Our data suggest this increase in CO2 uptake (larger than -6 μmol m-2 s-1) occurred during the initial thawing period and during the June-August growing season. However, there is a decreasing trend in total summer uptake beginning in 2011, continuing until the end of 2014. The mean diurnal pattern for the summer period over the course of 14 years (Figure below), indicates inter-annual variability associated with the key environmental controls on these CO2 fluxes. Monthly trends in Photosynthetically Active Radiation (PAR), net radiation, relative humidity as well as air temperature and soil temperature have consistently simultaneous effects on the variation in NEE. More significant effect of PAR than temperature on summer NEE had been observed for the first period of this study, however our ANOVA, multiple regression and t-test results showed a stronger effect of temperature than PAR in the recent years assuming that Arctic warming will be greater than average global warming. Also the diurnal pattern shows that the maximum daily carbon

  17. Vertical profiles of specific surface area, thermal conductivity and density of mid-latitude, Arctic and Antarctic snow: relationships between snow physics and climat

    NASA Astrophysics Data System (ADS)

    Domine, F.; Arnaud, L.; Bock, J.; Carmagnola, C.; Champollion, N.; Gallet, J.; Lesaffre, B.; Morin, S.; Picard, G.

    2011-12-01

    We have measured vertical profiles of specific surface area (SSA), thermal conductivity (TC) and density in snow from 12 different climatic regions featuring seasonal snowpacks of maritime, Alpine, taiga and tundra types, on Arctic sea ice, and from ice caps in Greenland and Antarctica. We attempt to relate snow physical properties to climatic variables including precipitation, temperature and its yearly variation, wind speed and its short scale temporal variations. As expected, temperature is a key variable that determines snow properties, mostly by determining the metamorphic regime (temperature gradient or equi-temperature) in conjunction with precipitation. However, wind speed and wind speed distribution also seem to have an at least as important role. For example high wind speeds determine the formation of windpacks of high SSA and high TC instead of depth hoar with lower values of these variables. The distribution of wind speed also strongly affects properties, as for example frequent moderate winds result in frequent snow remobilization, producing snow with higher SSA and lower TC than regions with the same average wind speeds, but with less frequent and more intense wind episodes. These strong effects of climate on snow properties imply that climate change will greatly modify snow properties, which in turn will affect climate, as for example changes in snow SSA modify albedo and changes in TC affect permafrost and the release of greenhouse gases from thawing permafrost. Some of these climate-snow feedbacks will be discussed.

  18. Sensitivity of Pliocene Arctic climate to orbital forcing, atmospheric CO2 and sea ice albedo parameterisation

    NASA Astrophysics Data System (ADS)

    Howell, Fergus; Haywood, Alan; Pickering, Steven

    2016-04-01

    General circulation model (GCM) simulations of the mid-Pliocene Warm Period (mPWP, 3.264 to 3.025 Myr ago) do not reproduce the magnitude of Northern Hemisphere high latitude surface air and sea surface temperature (SAT and SST) warming that proxy data indicates. There is also large uncertainty regarding the state of sea ice cover in the mPWP. Evidence for both perennial and seasonal mPWP Arctic sea ice is found in analyses of marine sediments, whilst in a multi-model ensemble of mPWP climate simulations, half of the ensemble simulated ice-free summer Arctic conditions. Given the strong influence that sea ice exerts on high latitude temperatures, a better understanding of the nature of mPWP Arctic sea ice would be highly beneficial in understanding proxy derived estimates of high latitude surface temperature change, and the ability of climate models to reproduce this. In GCM simulations, the mPWP is typically represented with fixed orbital forcing, usually identical to modern, and atmospheric CO2 concentrations of ˜ 400 ppm. However, orbital forcing varied over the ˜ 240,000 years of the mPWP, and it is likely that atmospheric CO2 varied as well. A previous study has suggested that the parameterisation of sea ice albedo in the HadCM3 GCM may not reflect the sea ice albedo for a warmer climate, where seasonal sea ice constitutes a greater proportion of the Arctic sea ice cover. These three factors, in isolation and combined, can greatly influence the simulation of Arctic sea ice cover and the degree of high latitude surface temperature warming. This paper explores the impact of various combinations of potential mPWP orbital forcing, atmospheric CO2 concentrations and minimum sea ice albedo on sea ice extent and high latitude warming. The focus is on the Northern Hemisphere, due to availability of proxy data, and the large data-model discrepancies in this region. Changes in orbital forcings are demonstrated to be sufficient to alter the Arctic sea ice simulated by

  19. Climate change and consequences in the Arctic: perception of climate change by the Nenets people of Vaigach Island

    PubMed Central

    Davydov, Alexander N.; Mikhailova, Galina V.

    2011-01-01

    Background Arctic climate change is already having a significant impact on the environment, economic activity, and public health. For the northern peoples, traditions and cultural identity are closely related to the natural environment so any change will have consequences for society in several ways. Methods A questionnaire was given to the population on the Vaigach island, the Nenets who rely to a large degree on hunting, fishing and reindeer herding for survival. Semi-structured interviews were also conducted about perception of climate change. Results Climate change is observed and has already had an impact on daily life according to more than 50% of the respondents. The winter season is now colder and longer and the summer season colder and shorter. A decrease in standard of living was noticeable but few were planning to leave. Conclusion Climate change has been noticed in the region and it has a negative impact on the standard of living for the Nenets. However, as of yet they do not want to leave as cultural identity is important for their overall well-being. PMID:22091216

  20. Improved Climate Prediction through a System Level Understanding of Arctic Terrestrial Ecosystems

    NASA Astrophysics Data System (ADS)

    Wullschleger, S. D.; Graham, D. E.; Hinzman, L. D.; Hubbard, S. S.; Liang, L.; Liljedahl, A. K.; Norby, R. J.; Rogers, A.; Rowland, J. C.; Thornton, P. E.; Torn, M. S.; Riley, W. J.; Wilson, C. J.

    2012-12-01

    Characterized by vast amounts of carbon stored in permafrost and a rapidly evolving landscape, the Arctic has emerged as an important focal point for the study of climate change. These are sensitive systems, yet the mechanisms responsible for those sensitivities are not well understood and many remain uncertain in terms of their representation in Earth System models. Increasing our confidence in climate projections for high-latitude regions of the world will require a coordinated set of investigations that target improved process understanding and model representation of important ecosystem-climate feedbacks. The Next-Generation Ecosystem Experiments (NGEE Arctic) seeks to address this challenge by quantifying the physical, chemical, and biological behavior of terrestrial ecosystems in Alaska. Initial research focuses on the highly dynamic landscapes of the North Slope where thaw lakes, drained thaw lake basins, and ice-rich polygonal ground offer distinct land units for investigation and modeling. Activities in the early stage of the project are focused on the Barrow Environmental Observatory (BEO), where a multi-disciplinary team of scientists will study interactions that drive critical climate feedbacks within these environments through greenhouse gas fluxes and changes in surface energy balance associated with permafrost degradation, and the many processes that arise as a result of these landscape dynamics. Our scaling approach builds on the hypothesis that the transfer of information across spatial scales can be organized around these discrete geomorphological units for which processes are represented explicitly at finer scales, with information passed to coarser scales through sub-grid parameterization of Earth System models. By extending an already well-established framework for fractional sub-grid area representations to allow dynamic sub-grid areas and hydrological and geophysical connections among sub-grid units, we expect to be able to characterize

  1. New insights into the Weichselian environment and climate of the East Siberian Arctic, derived from fossil insects, plants, and mammals

    NASA Astrophysics Data System (ADS)

    Sher, A. V.; Kuzmina, S. A.; Kuznetsova, T. V.; Sulerzhitsky, L. D.

    2005-03-01

    Multidisciplinary study of a key section on the Laptev Sea Coast (Bykovsky Peninsula, east Lena Delta) in 1998-2001 provides the most complete record of Middle and Late Weichselian environments in the East Siberian Arctic. The 40-m high Mamontovy Khayata cliff is a typical Ice Complex section built of icy silts with a network of large syngenetic polygonal ice wedges, and is richly fossiliferous. In combination with pollen, plant macrofossil and mammal fossils, a sequence of ca 70 insect samples provides a new interpretation of the environment and climate of the area between ca 50 and 12 ka. The large number of radiocarbon dates from the section, together with an extensive 14C database on mammal bones, allows chronological correlation of the various proxies. The Bykovsky record shows how climate change, and the Last Glacial Maximum in particular, affected terrestrial organisms such as insects and large grazing mammals. Both during the presumed "Karginsky Interstadial" (MIS 3) and the Sartanian Glacial (MIS 2), the vegetation remained a mosaic arctic grassland with relatively high diversity of grasses and herbs and dominance of xeric habitats: the tundra-steppe type. This biome was supported by a constantly very continental climate, caused by low sea level and enormous extension of shelf land. Variations within the broad pattern were caused mainly by fluctuations in summer temperature, related to global trends but overprinted by the effect of continentality. No major changes in humidity were observed nor were advances of modern-type forest or forest-tundra recorded, suggesting a major revision of the "Karginsky Interstadial" paradigm. The changing subtypes of the tundra-steppe environment were persistently favourable for mammalian grazers, which inhabited the shelf lowlands throughout the studied period. Mammal population numbers were lowered during the LGM, especially toward its end, and then flourished in a short, but impressive peak in the latest Weichselian, just

  2. Understanding How Climate Change Could Affect Tornadoes

    NASA Astrophysics Data System (ADS)

    Elsner, James; Guishard, Mark

    2014-11-01

    Current understanding of how tornadoes might change with global warming is limited. Incomplete data sets and the small-scale nature of tornadic events make it difficult to draw definitive conclusions. A consensus report on the climate of extreme storms found little evidence of trends in tornado frequency in the United States. However new research suggests a potential climate change footprint on tornadoes. Some of this research was presented at the First International Summit on Tornadoes and Climate Change, hosted by Aegean Conferences. The summit took place at the Minoa Palace in Chania, Greece, from 25 to 30 May 2014. Thirty delegates from eight countries—Greece, the United States, Germany, the United Kingdom, China, Japan, Israel, and Taiwan—participated.

  3. Influence of Climate Warming on Arctic Mammals? New Insights from Ancient DNA Studies of the collared lemming Dicrostonyx torquatus.

    NASA Astrophysics Data System (ADS)

    Prost, Stefan; Smirnov, Nickolay; Fedorov, Vadim B.; Sommer, Robert S.; Stiller, Mathias; Nagel, Doris; Knapp, Michael; Hofreiter, Michael

    2010-05-01

    Global temperature increased by approximately half a degree (Celsius) within the last 150 years. Even this moderate warming had major impacts on Earth's ecological and biological systems, especially in the Arctic where the magnitude of abiotic changes even exceeds those in temperate and tropical biomes. Therefore, understanding the biological consequences of climate change on high latitudes is of critical importance for future conservation of the species living in this habitat. The past 25,000 years can be used as a model for such changes, as they were marked by prominent climatic changes that influenced geographic distribution, demographic history and pattern of genetic variation of many extant species. We sequenced ancient and modern DNA of the collared lemming (Dicrostonyx torquatus), which is a key species of the arctic biota, from a single site (Pymva Shor, Northern Pre Urals, Russia) to see if climate warming events after the Last Glacial Maximum (LGM) had detectable effects on the genetic variation of this arctic rodent species, which is strongly associated with cold and dry climate. Using three dimensional network reconstruction and model-based approaches such as Approximate Bayesian Computation and Markov Chain Monte Carlo based Bayesian inference we show that there is evidence for a population decline in the collared lemming following the LGM, with the population size dropping to a minimum during the Greenland Interstadial 1 (Blling/Allerd) warming phase at 14.5 kyrs BP. Our results show that previous climate warming events had a strong influence on collard lemming populations. A similar population reduction due to predicted future climate change would have severe effects on the arctic ecosystem, as collared lemmings are a key species in the trophic interactions and ecosystem processes in the Arctic.

  4. Weather anomalies affect Climate Change microblogging intensity

    NASA Astrophysics Data System (ADS)

    Molodtsova, T.; Kirilenko, A.

    2012-12-01

    There is a huge gap between the scientific consensus and public understanding of climate change. Climate change has become a political issue and a "hot" topic in mass media that only adds the complexity to forming the public opinion. Scientists operate in scientific terms, not necessarily understandable by general public, while it is common for people to perceive the latest weather anomaly as an evidence of climate change. In 1998 Hansen et al. introduced a concept of an objectively measured subjective climate change indicator, which can relate public feeling that the climate is changing to the observed meteorological parameters. We tested this concept in a simple example of a temperature-based index, which we related to microblogging activity. Microblogging is a new form of communication in which the users describe their current status in short Internet messages. Twitter (http://twitter.com), is currently the most popular microblogging platform. There are multiple reasons, why this data is particularly valuable to the researches interested in social dynamics: microblogging is widely used to publicize one's opinion with the public; has broad, diverse audience, represented by users from many countries speaking different languages; finally, Twitter contains an enormous number of data, e.g., there were 1,284,579 messages related to climate change from 585,168 users in the January-May data collection. We collected the textual data entries, containing words "climate change" or "global warming" from the 1st of January, 2012. The data was retrieved from the Internet every 20 minutes using a specially developed Python code. Using geolocational information, blog entries originating from the New York urbanized area were selected. These entries, used as a source of public opinion on climate change, were related to the surface temperature, obtained from La Guardia airport meteorological station. We defined the "significant change" in the temperature index as deviation of the

  5. Contrasting Historical and Recent Breakup Styles on the Meade River of Arctic Alaska in the Context of a Warming Climate

    NASA Astrophysics Data System (ADS)

    Beck, R. A.; Hinkel, K. M.; Eisner, W. R.; Whiteman, D.; Arp, C. D.; Machida, R.; Cuomo, C.; Su, H.; Liu, H.; Kim, C.; Rettig, A.; Ivenso, C.; Yang, B.; Wu, Q.; Wang, S.; Frey, K. E.; Lenters, J. D.; Potter, B. L.

    2013-12-01

    Although data for temporal spring river ice breakup are available for a number of Arctic rivers, there is a paucity of information related to the type of breakup. The Arctic Climate Impact Assessment (ACIA) of 2005 predicted a transition from mechanical to thermal spring breakup of ice cover on arctic rivers, with this shift being greatest in exclusively Arctic watersheds where observed warming is most pronounced. We describe a rare instance of an entirely Arctic river with limited but well documented historical and recent data regarding the type of breakup. Time-series ground imagery of spring breakup from 1966, 1975, 1978, 2009, 2010 and 2012, in combination with interviews of local inhabitants, documents a shift from predominantly mechanical to predominantly thermal breakup after spring 1978 and by spring 2009 within the context of a locally and regionally warming Arctic. Recent (post-2010) and rare cloud-free visible satellite imagery shows an irregular pattern of breakup along the southern two thirds of the river. The resultant shift from predominantly mechanical to predominantly thermal breakup is predicted to result in significant changes to water, sediment, nutrient and organic carbon fluxes, as well as riparian ecology and human activities. Meade River Breakup - Spring 1966 Meade River Breakup - Spring 2010

  6. Late Holocene Peat Growth at the Northern Siberian Periphery and its Relation to Arctic Climate Change

    NASA Astrophysics Data System (ADS)

    Bauch, H. A.; Abramova, E.; Alenius, T.; Saarnisto, M.

    2014-12-01

    During the last postglacial evolution of the shallow northern Siberian shelf systems regional sea level in the Arctic came to its Holocene highstand some time between 5 to 6 ka. After that time a general stabilization of the sedimentary regime occurred. That is well noted in a drastic decrease in sedimentation rates observed in all sediment cores taken from middle to outer shelf water depths of the Laptev Sea. But, at water depths lower than 30 meters - i.e., in the inner shelf and nearer to the coasts - sedimentation continued at relatively higher rates, presumably due to input of terrigenous material from river runoff as well as coastal erosion. Compared with that latter process, the huge Lena Delta should comprise a region of sediment catchment where aggradation wins over erosion. However, little is known about the detailed history of this delta during the second half of the Holocene. In order to gain more insight into this issue we have investigated three islands within the Lena Delta. All of these are comprised of massive peat of several meters in thickness. Picking discrete specimens of water mosses (Sphagnum) only, we have radiocarbon-dated these peat sections. The depth/age relation of the sampled profiles reflect the growth rate of peat. It shows that the islands' history above the present-day delta-sea level is about 4000 yrs. old. Moreover, a significant change in peat growth occurred after 2500 yrs BP in both, accumulation and composition, and allows the conclusion of a major shift in Arctic environmental conditions since then. Thus, our results may add further information also for other coastal studies, as the ongoing degradation of the rather vulnerable permafrost coast in the Laptev Sea and elsewhere along the North Siberian margin is often mentioned in context with recent Arctic climate change due to global warming.

  7. Late Holocene Climate Change Inferred From Varved Proglacial Lake Sediments on Northeastern Baffin Island, Arctic Canada

    NASA Astrophysics Data System (ADS)

    Thomas, E. K.; Briner, J. P.; Axford, Y.

    2007-12-01

    The Arctic has a disproportionately large response to changes in radiative forcing of climate, and glaciers and arctic lacustrine ecosystems respond sensitively to these changes. Lacustrine ecosystems throughout the Arctic are undergoing rapid regime shifts, including dramatically increased primary productivity and changing aquatic floral and faunal assemblages. Our work on organic lake sediments from northeast Baffin Island shows a large increase in primary productivity, changes in insect (Chironomidae) assemblages including the disappearance of cold stenotherms, and a rise in chironomid-inferred summer water temperatures of at least 1.5°C over the past 50 years, reaching temperatures that were unprecedented in the past 5000 years. Here, we pursue the use of varve thickness, an abiotic temperature proxy, to expand our understanding of late Holocene temperature changes on northeast Baffin Island. We obtained a 14C- and 239+240Pu-dated surface core/percussion core pair from a proglacial lake. Together these cores span > 8000 years and the sediments are varved, as verified by the 239+240Pu analysis, for at least the past 700 years. Magnetic susceptibility was high during the early Holocene, decreased to near-zero values during the mid-Holocene and increased during the past 2500 years to reach the highest values seen in the record around 1000 years ago. Loss-on- ignition had an opposite trend, with the highest values in the mid-Holocene. Sedimentation rate was constant during most of the Holocene (0.03 cm yr -1) and increased during the past 1000 years to 0.05 cm yr -1. These parameters indicate that following the absence of an active glacier during the middle Holocene, glacier activity initiated ~2500 years ago and reached peak activity over the last 1000 years. Our ongoing work to obtain a varve-thickness record for at least the last 700 years, and its calibration to a nearby weather station, will be presented.

  8. Positive and negative feedbacks to climate change associated with methane emissions from arctic permafrost systems (Invited)

    NASA Astrophysics Data System (ADS)

    Walter Anthony, K. M.; Grosse, G.; Jones, B. M.

    2009-12-01

    Arctic permafrost contains 950 billion tons of organic carbon (C) in the surface tens of meters, an amount comparable to the current atmospheric CO2 burden of 750 billion tons. This C pool, which accumulated in permafrost over tens of thousands of years, is a threat to global climate because of its vulnerability to rapid microbial decomposition upon thaw, resulting in the release of greenhouse gases CO2 and CH4 to the atmosphere. Greenhouse gas release from thawing permafrost constitutes one of the most important positive feedbacks of terrestrial ecosystems to climate warming in a warmer world. Based on patterns of permafrost degradation during the present interglacial period, estimates of the amount of C remaining in permafrost today, long term field measurements of CH4 and CO2 flux, laboratory incubation experiments, and mass balance calculations of the efficiency of CH4 production from thawed permafrost, we predict that at least 50 billion tons of CH4 (equivalent to 10 times the current atmospheric methane burden) will escape from thermokarst (thaw) lakes in Siberia’s Yedoma Ice Complex as it warms and thaws. Additional CH4 will be released from the remainder of arctic lakes. Under current projections of arctic warming of 7-8 deg C by 2100, widespread permafrost thaw will release 0.1-0.2 billion tons of CH4 yr-1 by 2100, an order of magnitude more than its current source strength, adding another 20-40% of all human and natural sources of CH4 to the atmosphere. Permafrost thaw may lead to an additional source of methane if expanding thaw bulbs beneath lakes and rivers intersect faults and unconsolidated sediments leading to the escape of CH4 from geological sources, such as those recently observed on the North Slope of Alaska with a flux of 60-100 kg CH4 m-2 d-1. Thermokarst lake dynamics play a pivotal role in permafrost degradation and aggradation in the Arctic such that the landscape resembles a palimpsest of lakes and drained lake basins. Analysis of remote

  9. Modelling carbon responses of tundra ecosystems to historical and projected climate: Sensitivity of pan-Arctic carbon storage to temporal and spatial variation in climate

    USGS Publications Warehouse

    McGuire, A.D.; Clein, J.S.; Melillo, J.M.; Kicklighter, D.W.; Meier, R.A.; Vorosmarty, C.J.; Serreze, M.C.

    2000-01-01

    Historical and projected climate trends for high latitudes show substantial temporal and spatial variability. To identify uncertainties in simulating carbon (C) dynamics for pan-Arctic tundra, we compare the historical and projected responses of tundra C storage from 1921 to 2100 between simulations by the Terrestrial Ecosystem Model (TEM) for the pan-Arctic and the Kuparuk River Basin, which was the focus of an integrated study of C dynamics from 1994 to 1996. In the historical period from 1921 to 1994, the responses of net primary production (NPP) and heterotrophic respiration (RH) simulated for the Kuparuk River Basin and the pan-Arctic are correlated with the same factors; NPP is positively correlated with net nitrogen mineralization (NMIN) and RH is negatively correlated with mean annual soil moisture. In comparison to the historical period, the spatially aggregated responses of NPP and RH for the Kuparuk River Basin and the pan-Arctic in our simulations for the projected period have different sensitivities to temperature, soil moisture and NMIN. In addition to being sensitive to soil moisture during the projected period, RH is also sensitive to temperature and there is a significant correlation between RH and NMIN. We interpret the increases in NPP during the projected period as being driven primarily by increases in NMIN, and that the correlation between NPP and temperature in the projected period is a result primarily of the causal linkage between temperature, RH, and NMIN. Although similar factors appear to be controlling simulated regional-and biome-scale C dynamics, simulated C dynamics at the two scales differ in magnitude with higher increases in C storage simulated for the Kuparuk River Basin than for the pan-Arctic at the end of the historical period and throughout the projected period. Also, the results of the simulations indicate that responses of C storage show different climate sensitivities at regional and pan-Arctic spatial scales and that

  10. Climate change and the loss of organic archaeological deposits in the Arctic.

    PubMed

    Hollesen, Jørgen; Matthiesen, Henning; Møller, Anders Bjørn; Westergaard-Nielsen, Andreas; Elberling, Bo

    2016-01-01

    The Arctic is warming twice as fast as the global average with overlooked consequences for the preservation of the rich cultural and environmental records that have been stored for millennia in archaeological deposits. In this article, we investigate the oxic degradation of different types of organic archaeological deposits located in different climatic zones in West and South Greenland. The rate of degradation is investigated based on measurements of O2 consumption, CO2 production and heat production at different temperatures and water contents. Overall, there is good consistency between the three methods. However, at one site the, O2 consumption is markedly higher than the CO2 production, highlighting the importance of combining several measures when assessing the vulnerability of organic deposits. The archaeological deposits are highly vulnerable to degradation regardless of age, depositional and environmental conditions. Degradation rates of the deposits are more sensitive to increasing temperatures than natural soils and the process is accompanied by a high microbial heat production that correlates significantly with their total carbon content. We conclude that organic archaeology in the Arctic is facing a critical challenge that requires international action. PMID:27356878

  11. Increasing contaminant burdens in an arctic fish, Burbot ( Lota lota ), in a warming climate.

    PubMed

    Carrie, J; Wang, F; Sanei, H; Macdonald, R W; Outridge, P M; Stern, G A

    2010-01-01

    The temporal patterns of mercury (Hg), polychlorinated biphenyls (PCBs), and other contaminants in Arctic aquatic biota are usually attributed to changing atmospheric sources. However, climate variability and change is another means of altering contaminant fate and bioavailability. We show here that the concentrations of Hg and PCBs in Mackenzie River burbot ( Lota lota ), a top predator fish and important staple food for northern Canadian communities, have increased significantly over the last 25 years despite falling or stable atmospheric concentrations, suggesting that environmental processes subsequent to atmospheric transport are responsible. Using a dated sediment core from a tributary lake near the Mackenzie River sampling site, we show that variations in Hg concentrations downcore are strongly associated with labile, algal-derived organic matter (OM). Strong temporal correlations between increasing primary productivity and biotic Hg and PCBs as reflected by burbot suggest that warming temperatures and reduced ice cover may lead to increased exposure to these contaminants in high trophic level Arctic freshwater biota. PMID:19957995

  12. Climate change and the loss of organic archaeological deposits in the Arctic

    PubMed Central

    Hollesen, Jørgen; Matthiesen, Henning; Møller, Anders Bjørn; Westergaard-Nielsen, Andreas; Elberling, Bo

    2016-01-01

    The Arctic is warming twice as fast as the global average with overlooked consequences for the preservation of the rich cultural and environmental records that have been stored for millennia in archaeological deposits. In this article, we investigate the oxic degradation of different types of organic archaeological deposits located in different climatic zones in West and South Greenland. The rate of degradation is investigated based on measurements of O2 consumption, CO2 production and heat production at different temperatures and water contents. Overall, there is good consistency between the three methods. However, at one site the, O2 consumption is markedly higher than the CO2 production, highlighting the importance of combining several measures when assessing the vulnerability of organic deposits. The archaeological deposits are highly vulnerable to degradation regardless of age, depositional and environmental conditions. Degradation rates of the deposits are more sensitive to increasing temperatures than natural soils and the process is accompanied by a high microbial heat production that correlates significantly with their total carbon content. We conclude that organic archaeology in the Arctic is facing a critical challenge that requires international action. PMID:27356878

  13. Multiproxy paleoecological evidence of Holocene climatic changes on the Boothia Peninsula, Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Fortin, Marie-Claude; Gajewski, Konrad

    2016-05-01

    A study of chironomid remains in the sediments of Lake JR01 on the Boothia Peninsula in the Central Canadian Arctic provides a high-resolution record of mean July air temperatures for the last 6.9 ka. Diatom and pollen studies have previously been published from this core. Peak Holocene temperatures occurred prior to 5.0 ka, a time when overall aquatic and terrestrial biological production was high. Chironomid-inferred summer air temperatures reached up to 7.5°C during this period. The region of Lake JR01 cooled over the mid- to late-Holocene, with high biological production between 6.1 and 5.4 ka. Biological production decreased again at ∼2 ka and the rate of cooling increased in the past 2 ka, with coolest temperatures occurring between 0.46 and 0.36 ka, coinciding with the Little Ice Age. Although biological production increased in the last 150 yr, the reconstructed temperatures do not indicate a warming during this time. During transitions, either warming or cooling, chironomid production increases, suggesting an ecosystem-level response to climate variability, seen at a number of lakes across the Arctic.

  14. Climate change and the loss of organic archaeological deposits in the Arctic

    NASA Astrophysics Data System (ADS)

    Hollesen, Jørgen; Matthiesen, Henning; Møller, Anders Bjørn; Westergaard-Nielsen, Andreas; Elberling, Bo

    2016-06-01

    The Arctic is warming twice as fast as the global average with overlooked consequences for the preservation of the rich cultural and environmental records that have been stored for millennia in archaeological deposits. In this article, we investigate the oxic degradation of different types of organic archaeological deposits located in different climatic zones in West and South Greenland. The rate of degradation is investigated based on measurements of O2 consumption, CO2 production and heat production at different temperatures and water contents. Overall, there is good consistency between the three methods. However, at one site the, O2 consumption is markedly higher than the CO2 production, highlighting the importance of combining several measures when assessing the vulnerability of organic deposits. The archaeological deposits are highly vulnerable to degradation regardless of age, depositional and environmental conditions. Degradation rates of the deposits are more sensitive to increasing temperatures than natural soils and the process is accompanied by a high microbial heat production that correlates significantly with their total carbon content. We conclude that organic archaeology in the Arctic is facing a critical challenge that requires international action.

  15. Climatic change of sea ice mean thickness in the Arctic basin

    SciTech Connect

    Nagurny, A.P.

    1996-12-31

    A method for automatically monitoring sea ice thickness by measuring ice-plate vibration is proposed. Two energy maximums are clearly manifested in the spectrum of ice cover vibrations, corresponding to the resonant waves (the equality of ice eigen frequency as a plate and upper water layer without ice cover) and to the waves at the minimum of the dispersion curve of the ice-water system. The free vibrations of the resonant waves have low amplitudes and can be adequately described by linear theory of elastic gravity wave propagation. Data are presented for sea ice thickness determined by measuring elastic-gravity waves at points in the Arctic basin for the years 1970 through 1992. During this period, a linear decrease in sea ice thickness was observed. The thickness decreased by 12-14 centimeters, or 3 to 4% of average thickenss, overall. Taking into account the significant scattering of data, a trend of climatic warming in the atmosphere-Arctic Ocean system is indicated. 11 refs., 2 figs.

  16. High frequency and wavenumber ocean-ice-atmosphere coupling in the Regional Arctic Climate Model

    NASA Astrophysics Data System (ADS)

    Roberts, A.; Maslowski, W.; Jakacki, J.; Higgins, M.; Craig, T.; Cassano, J. J.; Gutowski, W. J.; Lettenmaier, D. P.

    2011-12-01

    We present results from the fully coupled version of the Regional Arctic Climate Model (RACM) on the spectral and noise characteristics of high-frequency (20-minute) dynamic coupling between the 9km Parallel Ocean Program/Community Ice Code (POP/CICE) and 50km Weather Research and Forecast model (WRF) using the CPL7 framework. We have employed an array of signal processing techniques to investigate: 1) Synchronization of the inertial response of POP and CICE to the passage of storms in WRF, and wavelet coherence of these results with in-situ observations of drift and deformation in the Arctic Ocean; 2) High-wavenumber signals in the sea ice deformation pattern resulting super-inertial coupling and aliasing of the wind field in CPL7, and the influence of these factors on the transmission of wind stress curl into the deep ocean; 3) The impact of high frequency ocean-ice-atmosphere coupling on the modeled sea ice thickness distribution. For this last set of experiments, we have run a set of winter band-limited integrations, filtering out high-frequency WRF inputs to the sea ice and ocean components. These experiments suggest the most pronounced regional influence of super-inertial coupling on sea ice mass extends from the Greenland Sea through Fram Strait to the North Pole, although there is also a significant basin-wide deformation pattern emanating from high spatiotemporal coupling in RACM.

  17. Holocene paleoclimate data from the Arctic: testing models of global climate change

    NASA Astrophysics Data System (ADS)

    CAPE Project Members

    2001-06-01

    To evaluate the spatial variability of Arctic climate change during the present interglacial, CAPE Project Members compiled well-dated terrestrial, marine, and ice-core paleoenvironmental records spanning the past 10-12 thousand years (ka). Six tundra biomes of increasing summer temperature requirements were defined based on regionally coherent pollen assemblages. Using a rule-based approach, pollen spectra were converted to tundra, forest/tundra, or forest biomes ranked by their average growing season requirements. Marine sea-surface reconstructions were based on proxy data following a similar rule-based approach. From these data-based reconstructions, departures in summer temperatures from modern normals were calculated in 1 ka time slices through the Holocene. To test predictive models, data-based summer temperature reconstructions were compared with general circulation model (GCM) simulations for 10 ka and 6 ka ago. Paleodata and model results both show that warming occurred earlier across Beringia and Asia relative to lands adjacent to the North Atlantic, and that Late Holocene cooling was most apparent in the North Atlantic region. However, the GCM over-predicts the magnitude of Mid-Holocene warming over northern Asia and underestimates the intensification of the North Atlantic drift in the early Holocene. Strong spatial variability in environmental response during the Holocene, despite symmetric (insolation) forcing, suggests that any future changes, whether caused by anthropogenic or natural factors, are unlikely to result in a uniform change across the Arctic, adding additional complexity to forecasts of global impacts.

  18. How increasing CO sub 2 and climate change affect forests

    SciTech Connect

    Graham, R.L.; Turner, M.G.; Dale, V.H. )

    1990-09-01

    The strong relationship among climate, atmosphere, soils, biota, and human activities provides a solid basis for anticipating changes in terrestrial biomes in response to changes in the global environment. This article examines potential forest responses to elevated carbon dioxide in conjunction with climatic change. Key ecological processes and how human intervention can affect those processes is presented.

  19. USGS Arctic science strategy

    USGS Publications Warehouse

    Shasby, Mark; Smith, Durelle

    2015-01-01

    The United States is one of eight Arctic nations responsible for the stewardship of a polar region undergoing dramatic environmental, social, and economic changes. Although warming and cooling cycles have occurred over millennia in the Arctic region, the current warming trend is unlike anything recorded previously and is affecting the region faster than any other place on Earth, bringing dramatic reductions in sea ice extent, altered weather, and thawing permafrost. Implications of these changes include rapid coastal erosion threatening villages and critical infrastructure, potentially significant effects on subsistence activities and cultural resources, changes to wildlife habitat, increased greenhouse-gas emissions from thawing permafrost, threat of invasive species, and opening of the Arctic Ocean to oil and gas exploration and increased shipping. The Arctic science portfolio of the U.S. Geological Survey (USGS) and its response to climate-related changes focuses on landscapescale ecosystem and natural resource issues and provides scientific underpinning for understanding the physical processes that shape the Arctic. The science conducted by the USGS informs the Nation's resource management policies and improves the stewardship of the Arctic Region.

  20. An atmosphere-ocean GCM modelling study of the climate response to changing Arctic seaways in the early Cenozoic.

    NASA Astrophysics Data System (ADS)

    Roberts, C. D.; Legrande, A. N.; Tripati, A. K.

    2008-12-01

    previous findings on the potential influence of Arctic gateways on ocean overturning and also suggests that Northern Hemisphere climate, particularly in the North Atlantic, was very sensitive to changes in Arctic seaways. This result is of particular significance when considered in the context of the Paleocene Eocene Thermal Maximum (PETM). Volcanic activity prior to the PETM may have been responsible for the formation of a sub-aerial barrier in the North Atlantic, and consequently may have driven warming of intermediate waters sufficient to destabilize methane clathrates. Evidence for freshening of Arctic ocean waters prior to the PETM would support this hypothesis.

  1. How does spatial variability of climate affect catchment streamflow predictions?

    EPA Science Inventory

    Spatial variability of climate can negatively affect catchment streamflow predictions if it is not explicitly accounted for in hydrologic models. In this paper, we examine the changes in streamflow predictability when a hydrologic model is run with spatially variable (distribute...

  2. Projected Impact of Climate Change on the Energy Budget of the Arctic Ocean by a Global Climate Model

    NASA Technical Reports Server (NTRS)

    Miller, James R.; Russell, Gary L.; Hansen, James E. (Technical Monitor)

    2001-01-01

    The annual energy budget of the Arctic Ocean is characterized by a net heat loss at the air-sea interface that is balanced by oceanic heat transport into the Arctic. The energy loss at the air-sea interface is due to the combined effects of radiative, sensible, and latent heat fluxes. The inflow of heat by the ocean can be divided into two components: the transport of water masses of different temperatures between the Arctic and the Atlantic and Pacific Oceans and the export of sea ice, primarily through Fram Strait. Two 150-year simulations (1950-2099) of a global climate model are used to examine how this balance might change if atmospheric greenhouse gases (GHGs) increase. One is a control simulation for the present climate with constant 1950 atmospheric composition, and the other is a transient experiment with observed GHGs from 1950 to 1990 and 0.5% annual compounded increases of CO2 after 1990. For the present climate the model agrees well with observations of radiative fluxes at the top of the atmosphere, atmospheric advective energy transport into the Arctic, and surface air temperature. It also simulates the seasonal cycle and summer increase of cloud cover and the seasonal cycle of sea-ice cover. In addition, the changes in high-latitude surface air temperature and sea-ice cover in the GHG experiment are consistent with observed changes during the last 40 and 20 years, respectively. Relative to the control, the last 50-year period of the GHG experiment indicates that even though the net annual incident solar radiation at the surface decreases by 4.6 W(per square meters) (because of greater cloud cover and increased cloud optical depth), the absorbed solar radiation increases by 2.8 W(per square meters) (because of less sea ice). Increased cloud cover and warmer air also cause increased downward thermal radiation at the surface so that the net radiation into the ocean increases by 5.0 Wm-2. The annual increase in radiation into the ocean, however, is

  3. Sensitivity of Pliocene Arctic climate to orbital forcing, atmospheric CO2 and sea ice albedo parameterisation

    NASA Astrophysics Data System (ADS)

    Howell, Fergus W.; Haywood, Alan M.; Dowsett, Harry J.; Pickering, Steven J.

    2016-05-01

    General circulation model (GCM) simulations of the mid-Pliocene Warm Period (mPWP, 3.264 to 3.025 Myr ago) do not reproduce the magnitude of Northern Hemisphere high latitude surface air and sea surface temperature (SAT and SST) warming that proxy data indicate. There is also large uncertainty regarding the state of sea ice cover in the mPWP. Evidence for both perennial and seasonal mPWP Arctic sea ice is found through analyses of marine sediments, whilst in a multi-model ensemble of mPWP climate simulations, half of the ensemble simulated ice-free summer Arctic conditions. Given the strong influence that sea ice exerts on high latitude temperatures, an understanding of the nature of mPWP Arctic sea ice would be highly beneficial. Using the HadCM3 GCM, this paper explores the impact of various combinations of potential mPWP orbital forcing, atmospheric CO2 concentrations and minimum sea ice albedo on sea ice extent and high latitude warming. The focus is on the Northern Hemisphere, due to availability of proxy data, and the large data-model discrepancies in this region. Changes in orbital forcings are demonstrated to be sufficient to alter the Arctic sea ice simulated by HadCM3 from perennial to seasonal. However, this occurs only when atmospheric CO2 concentrations exceed 300 ppm. Reduction of the minimum sea ice albedo from 0.5 to 0.2 is also sufficient to simulate seasonal sea ice, with any of the combinations of atmospheric CO2 and orbital forcing. Compared to a mPWP control simulation, monthly mean increases north of 60°N of up to 4.2 °C (SST) and 9.8 °C (SAT) are simulated. With varying CO2, orbit and sea ice albedo values we are able to reproduce proxy temperature records that lean towards modest levels of high latitude warming, but other proxy data showing greater warming remain beyond the reach of our model. This highlights the importance of additional proxy records at high latitudes and ongoing efforts to compare proxy signals between sites.

  4. Studies of dynamical processes affecting global climate

    SciTech Connect

    Keller, C.; Cooper, D.; Eichinger, W.

    1998-12-31

    This is the final report of a three-year, Laboratory Directed Research and Development project at the Los Alamos National Laboratory (LANL). The main objective was, by a combined theoretical and observational approach, to develop improved models of dynamic processes in the oceans and atmosphere and to incorporate them into large climate codes, chiefly in four main areas: numerical physics, chemistry, water vapor, and ocean-atmosphere interactions. Main areas of investigation included studies of: cloud parameterizations for global climate codes, Lidar and the planetary boundary layer, chemistry, climate variability using coupled ocean-atmospheric models, and numerical physical methods. This project employed a unique approach that included participation of a number of University of California faculty, postdoctoral fellows and graduate students who collaborated with Los Alamos research staff on specific tasks, thus greatly enhancing the research output. Overall accomplishments during the sensing of the atmospheric planetary were: (1) first two- and three-dimensional remote sensing of the atmospheric planetary boundary layer using Lidars, (2) modeling of 20-year cycle in both pressure and sea surface temperatures in North Pacific, (3) modeling of low frequency internal variability, (4) addition of aerosols to stratosphere to simulate Pinatubo effect on ozone, (5) development of fast, comprehensive chemistry in the troposphere for urban pollution studies, (6) new prognostic cloud parameterization in global atmospheric code remedied problems with North Pacific atmospheric circulation and excessive equatorial precipitation, (7) development of a unique aerosol analysis technique, the aerosol time-of-flight mass spectrometer (ATOFMS), which allows real-time analysis of the size and chemical composition of individual aerosol particles, and (8) numerical physics applying Approximate Inertial Manifolds to ocean circulation. 14 refs., 6 figs.

  5. Integrating Research on Global Climate Change and Human Use of the Oceans: a Geospatial Method for Daily Monitoring of Sea Ice and Ship Traffic in the Arctic

    NASA Astrophysics Data System (ADS)

    Eucker, W.; McGillivary, P. A.

    2012-12-01

    One apparent consequence of global climate change has been a decrease in the extent and thickness of Arctic sea ice more rapidly than models have predicted, while Arctic ship traffic has likewise increased beyond economic predictions. To ensure representative observations of changing climate conditions and human use of the Arctic Ocean, we concluded a method of tracking daily changes in both sea ice and shipping in the Arctic Ocean was needed. Such a process improves the availability of sea ice data for navigational safety and allows future developments to be monitored for understanding of ice and shipping in relation to policy decisions appropriate to optimize sustainable use of a changing Arctic Ocean. The impetus for this work was the 2009 Arctic Marine Shipping Assessment (AMSA) which provided baseline data on Arctic ship traffic. AMSA was based on responses from circumpolar countries, was manpower intensive, and took years to compile. A more timely method of monitoring human use of the Arctic Ocean was needed. To address this, a method of monitoring sea ice on a scale relevant to ship-navigation (<10km) was developed and implemented in conjunction with arctic ship tracking using S-AIS (Satellite Automatic Identification Systems). S-AIS is internationally required on ships over a certain size, which includes most commercial vessels in the Arctic Ocean. Daily AIS and sea ice observations were chosen for this study. Results of this method of geospatial analysis of the entire arctic are presented for a year long period from April 1, 2010 to March 31, 2011. This confirmed the dominance of European Arctic ship traffic. Arctic shipping is maximal during August and diminishes in September with a minimum in winter, although some shipping continues year-round in perennially ice-free areas. Data are analyzed for the four principal arctic quadrants around the North Pole by season for number and nationality of vessels. The goal of this study was not merely to monitor ship

  6. Deglacial and Holocene Evolution of Climate and Terrestrial Ecosystems in the Western Arctic.

    NASA Astrophysics Data System (ADS)

    Edwards, M. E.

    2006-12-01

    The late- and post-glacial history of the Western Arctic land area is distinguished by the region being largely unglaciated (away from the coastal cordillera), and by a considerable reduction in areal extent due to sea-level rise. Between ca. 15 and 10 cal ka B.P. rising summer temperatures and increasing precipitation related to orbital forcing and adjustments in the hemispheric circulation resulted in widespread replacement of herbaceous vegetation with deciduous woody plants, rising lake levels, reduction of eolian activity, and the onset of thermokarst erosion. These changes had impacts at both global and regional levels, e.g., reduced atmospheric dust loading, increased carbon flux to the atmosphere, and feedbacks to the surface energy balance. The Younger Dryas event (ca. 12.9-11.6 cal ka B.P.) is not strongly expressed in terrestrial records. Some localities near the Pacific coast and in eastern Siberia record a weak to moderate climatic reversal, but central, northern, and eastern areas show no consistent signal. This suggests a muted response of the North Pacific and/or adjacent lands to events in the North Atlantic. However, the nearly coincident flooding and eventual breaching of the Bering land bridge probably reduced continentality in adjacent regions and may be linked to early-Holocene increases in effective moisture in both summer and winter. At ca. 10 cal ka B.P. evergreen conifers expanded to dominance or co-dominance much of the forest zone on both sides of the Bering Strait. This appears to be an example of a moisture-driven vegetation change in a region normally expected to respond largely to temperature. Particularly in Alaska and NW Canada, it likely led to two significant ecosystem changes: a vegetation-driven shift in the fire regime and enhanced paludification. The former could have influenced atmospheric chemistry and the latter nutrient availability, the status of permafrost, and the export of organic carbon and other nutrients to

  7. Climate change and Arctic ecosystems: 2. Modeling, paleodata-model comparisons, and future projections

    USGS Publications Warehouse

    Kaplan, J.O.; Bigelow, N.H.; Prentice, I.C.; Harrison, S.P.; Bartlein, P.J.; Christensen, T.R.; Cramer, W.; Matveyeva, N.V.; McGuire, A.D.; Murray, D.F.; Razzhivin, V.Y.; Smith, B.; Walker, D. A.; Anderson, P.M.; Andreev, A.A.; Brubaker, L.B.; Edwards, M.E.; Lozhkin, A.V.

    2003-01-01

    Large variations in the composition, structure, and function of Arctic ecosystems are determined by climatic gradients, especially of growing-season warmth, soil moisture, and snow cover. A unified circumpolar classification recognizing five types of tundra was developed. The geographic distributions of vegetation types north of 55??N, including the position of the forest limit and the distributions of the tundra types, could be predicted from climatology using a small set of plant functional types embedded in the biogeochemistry-biogeography model BIOME4. Several palaeoclimate simulations for the last glacial maximum (LGM) and mid-Holocene were used to explore the possibility of simulating past vegetation patterns, which are independently known based on pollen data. The broad outlines of observed changes in vegetation were captured. LGM simulations showed the major reduction of forest, the great extension of graminoid and forb tundra, and the restriction of low- and high-shrub tundra (although not all models produced sufficiently dry conditions to mimic the full observed change). Mid-Holocene simulations reproduced the contrast between northward forest extension in western and central Siberia and stability of the forest limit in Beringia. Projection of the effect of a continued exponential increase in atmospheric CO2 concentration, based on a transient ocean-atmosphere simulation including sulfate aerosol effects, suggests a potential for larger changes in Arctic ecosystems during the 21st century than have occurred between mid-Holocene and present. Simulated physiological effects of the CO2 increase (to > 700 ppm) at high latitudes were slight compared with the effects of the change in climate.

  8. Wave climate in the Arctic 1992-2014: seasonality, trends, and wave-ice influence

    NASA Astrophysics Data System (ADS)

    Girard-Ardhuin, Fanny; Stopa, Justin; Ardhuin, Fabrice

    2016-04-01

    The diminishing sea ice has direct implications on the wave field which is mainly dependent on the ice-free area and wind. Over the past decade, the Arctic sea ice has diminished which directly impacts the wave field. This study characterizes the wave climate in the Arctic using detailed sea state information from a wave hindcast and merged altimeter dataset spanning 1992-2014. The waves are driven by winds from the Climate Forecast System Reanalysis. Ice concentrations derived from satellites with a grid spacing of 12.5 km are sufficiently able to resolve important features in the marginal ice zone. Before implementation, suitable wind forcing is identified and the validity and consistency of the wave hindcast is verified with altimeters. The seasonal ice advance and retreat largely dictates the waves and creates distinct features in the wind-waves and swells. The Nordic-Greenland Sea is dominated by swells from the North Atlantic while the coastal regions and semi-enclosed seas of the Kara, Laptev, Chukchi, and Beaufort have a more equal proportion of wind-waves and swells. Trends in the altimeters and model are in agreement and show increasing wave activities in the Baffin Bay, Beaufort, Chukchi, Laptev, and Kara Seas due to the loss of sea ice. In the Nordic-Greenland Sea, there is a decreasing trend related to changes in the wind field by North Atlantic Oscillation. The waves also influence the sea ice. Two distinctly different wave-ice environments are identified and selected events demonstrate the importance of waves in the marginal ice zone. The crux of the research identifies the need for continued study and improvement of wave-ice interaction.

  9. Long-term changes of the benthos in the Arctic area under influence of the climatic fluctuations

    SciTech Connect

    Denisenko, S.G.; Denisenko, N.V.

    1996-12-31

    The Barents Sea, with the White Sea, is one of the most investigated Russian northern seas. For this reason benthos material sampled during the current century in the expeditions to the Barents Sea is important because of long-term changes in the bottom fauna in the Arctic Seas. The changes can occur under the influence of the long-term climatic fluctuations, as well as under human impact. This knowledge of the changes of the bottom fauna in the Arctic Seas can be useful in forecasting future global climatic changes. The aim of the present work was to understand how the climatic fluctuations influence the changes of the total biomass and abundance of zoobenthos. The biomass data of the 4 total benthic surveys (1924--1927; 1958--1959; 1968--1970; 1988--1993) were analyzed.

  10. Northeast Greenland Caves Project: first results from a speleothem-derived record of climate change for the Arctic

    NASA Astrophysics Data System (ADS)

    Moseley, Gina; Edwards, R. Lawrence; Cheng, Hai; Lu, Yanbin; Spoetl, Christoph

    2016-04-01

    Multiple lines of evidence currently exist that demonstrate the climate is changing across our planet, and that the Arctic in particular is highly sensitive to these changes, warming up twice as fast as the global average. Understanding how the climate in the Arctic will develop in the future and its subsequent effects is thus a major concern. In order to improve understanding of the climate system within the Arctic, we have collected a suite of calcite flowstone samples from solution-formed caves in the Ordovician-Silurian Centrum limestone of Kronprins Christian Land, Northeast Greenland. Under contemporary conditions, the region is arid, barren, and permanently frozen, however, the presence of these caves and thick flowstone deposits indicates a previous milder climate. During the summer of 2015, 26 caves were documented at 80.4 degrees north, and 16 speleothem samples collected. Here we present the results of the first U-Th dating and stable isotope analyses. U-Th ages show that the flowstone was deposited intermittently between 220 and 500 thousand years ago (ka) with additional smaller growth periods at c. 108 and 5.7 ka, thus indicating the presence of flowing water at these times. δ18O of the speleothem calcite varies between c. -12 and -16.5 ‰ and displays millennial-scale variability. Our initial results thus demonstrate the potential of these speleothem deposits for extending our knowledge of Greenland's climate beyond the limit of the Greenland ice cores.

  11. Landscape fragmentation affects responses of avian communities to climate change.

    PubMed

    Jarzyna, Marta A; Porter, William F; Maurer, Brian A; Zuckerberg, Benjamin; Finley, Andrew O

    2015-08-01

    Forecasting the consequences of climate change is contingent upon our understanding of the relationship between biodiversity patterns and climatic variability. While the impacts of climate change on individual species have been well-documented, there is a paucity of studies on climate-mediated changes in community dynamics. Our objectives were to investigate the relationship between temporal turnover in avian biodiversity and changes in climatic conditions and to assess the role of landscape fragmentation in affecting this relationship. We hypothesized that community turnover would be highest in regions experiencing the most pronounced changes in climate and that these patterns would be reduced in human-dominated landscapes. To test this hypothesis, we quantified temporal turnover in avian communities over a 20-year period using data from the New York State Breeding Atlases collected during 1980-1985 and 2000-2005. We applied Bayesian spatially varying intercept models to evaluate the relationship between temporal turnover and temporal trends in climatic conditions and landscape fragmentation. We found that models including interaction terms between climate change and landscape fragmentation were superior to models without the interaction terms, suggesting that the relationship between avian community turnover and changes in climatic conditions was affected by the level of landscape fragmentation. Specifically, we found weaker associations between temporal turnover and climatic change in regions with prevalent habitat fragmentation. We suggest that avian communities in fragmented landscapes are more robust to climate change than communities found in contiguous habitats because they are comprised of species with wider thermal niches and thus are less susceptible to shifts in climatic variability. We conclude that highly fragmented regions are likely to undergo less pronounced changes in composition and structure of faunal communities as a result of climate change

  12. Improved cloud parameterization for Arctic climate simulations based on satellite data

    NASA Astrophysics Data System (ADS)

    Klaus, Daniel; Dethloff, Klaus; Dorn, Wolfgang; Rinke, Annette

    2015-04-01

    The defective representation of Arctic cloud processes and properties remains a crucial problem in climate modelling and in reanalysis products. Satellite-based cloud observations (MODIS and CPR/CALIOP) and single-column model simulations (HIRHAM5-SCM) were exploited to evaluate and improve the simulated Arctic cloud cover of the atmospheric regional climate model HIRHAM5. The ECMWF reanalysis dataset 'ERA-Interim' (ERAint) was used for the model initialization, the lateral boundary forcing as well as the dynamical relaxation inside the pan-Arctic domain. HIRHAM5 has a horizontal resolution of 0.25° and uses 40 pressure-based and terrain-following vertical levels. In comparison with the satellite observations, the HIRHAM5 control run (HH5ctrl) systematically overestimates total cloud cover, but to a lesser extent than ERAint. The underestimation of high- and mid-level clouds is strongly outweighed by the overestimation of low-level clouds. Numerous sensitivity studies with HIRHAM5-SCM suggest (1) the parameter tuning, enabling a more efficient Bergeron-Findeisen process, combined with (2) an extension of the prognostic-statistical (PS) cloud scheme, enabling the use of negatively skewed beta distributions. This improved model setup was then used in a corresponding HIRHAM5 sensitivity run (HH5sens). While the simulated high- and mid-level cloud cover is improved only to a limited extent, the large overestimation of low-level clouds can be systematically and significantly reduced, especially over sea ice. Consequently, the multi-year annual mean area average of total cloud cover with respect to sea ice is almost 14% lower than in HH5ctrl. Overall, HH5sens slightly underestimates the observed total cloud cover but shows a halved multi-year annual mean bias of 2.2% relative to CPR/CALIOP at all latitudes north of 60° N. Importantly, HH5sens produces a more realistic ratio between the cloud water and ice content. The considerably improved cloud simulation manifests in

  13. Polar stratospheric ozone: interactions with climate change, results from the EU project RECONCILE, and the 2010/11 Arctic ozone hole

    NASA Astrophysics Data System (ADS)

    von Hobe, Marc

    2013-04-01

    One of the most profound and well known examples of human impacts on atmospheric chemistry is the so called ozone hole. During the second half of the 20th century, anthropogenic emissions of chlorofluorocarbons (CFCs) led to a significant increase in stratospheric chlorine levels and hence the rate of ozone removal by catalytic cycles involving chlorine. While CFCs were essentially banned by the 1987 Montreal Protocol and its subsequent amendments, and stratospheric chlorine levels have recently started to decline again, another anthropogenic influence may at least delay the recovery of the stratospheric ozone layer: climate change, with little doubt a result of human emissions of carbon dioxide and other greenhouse gases, has led to changes in stratospheric temperature and circulation. The large ozone losses that typically occur in polar regions in spring are particularly affected by these changes. Here, we give an overview of the ozone-climate interactions affecting polar stratospheric ozone loss, and present latest results from the international research project RECONCILE funded by the European Commission. Remaining open questions will be discussed including the possible impacts of recently suggested geoengineering concepts to artificially enhance the stratospheric aerosol loading. A special focus will also be put on the 2010/11 Arctic winter that saw the first Arctic Ozone hole, including an impact study on surface UV radiation in the densely populated northern mid-latitudes.

  14. Peeking Under the Ice… Literally: Records of Arctic Climate Change from Radiocarbon Dating Moss Emerging from Beneath Retreating Glaciers

    NASA Astrophysics Data System (ADS)

    Briner, J. P.; Schweinsberg, A.; Miller, G. H.; Lifton, N. A.; Beel, C. R.; Bennike, O.

    2014-12-01

    Dramatic changes are taking place throughout the Arctic. Many glaciers have already melted away completely, and most others are well on their way as rising snowline elevations promise continued glacier retreat. Emerging from beneath retreating glacier margins is a landscape rich in information about past climate and glacier changes. Within newly exposed bedrock is an inventory of cosmogenic nuclides that archive past ice cover timing and duration. Lake basins re-appearing due to retreating ice preserve sediment archives that tell of cooling climate and advancing ice. And ancient surfaces vegetated with tundra communities that have long been entombed beneath frozen-bedded ice caps are now being revealed for the first time in millennia. This presentation will focus on the climate and glacier record derived from radiocarbon dating of in situ moss recently exhumed from retreating local ice cap margins on western Greenland. Dozens of radiocarbon ages from moss group into several distinct modes, which are interpreted as discrete times of persistent summer cooling and resultant glacier expansion. The data reveal a pattern of glacier expansion beginning ~5000 years ago, followed by periods of glacier growth around 3500 and 1500 years ago. Because these times of glacier expansion are recorded at many sites in western Greenland and elsewhere in the Arctic, they are interpreted as times of step-wise summer cooling events during the Holocene. These non-linear climate changes may be a result of feedbacks that amplify linear insolation forcing of Holocene climate. In addition to these insights into the Arctic climate system, the antiquity of many radiocarbon ages of ice-killed moss indicate that many arctic surfaces are being re-exposed for the first time in millennia due to retreating ice, emphasizing the unprecedented nature of current summer warming.

  15. Climate change, its consequences in the Arctic and around the world

    NASA Astrophysics Data System (ADS)

    Jayer, Sophie; Le Divenah, Claudie; Rosetti, Alexandra

    2010-05-01

    CLIMATE CHANGE, ITS CONSEQUENCES IN THE ARCTIC AND AROUND THE WORLD This project has been led in a French European Class either in physics, chemistry, geology, biology and English by: - Sophie Jayer (Biology and geology teacher) - Claudie Le Divenah (Physics and Chemistry teacher) - Alexandra Rosetti (English teacher) As it was a European class, all the classes were held in English. The goals were - to have the students study both sciences and English - to show them that all these subjects were linked in real life and how important English was for scientists - To give them a glimpse of what scientific researches were both in the field and in a lab - To get them involved in the polar year - To make them work on the notion of world citizenship and raise their awareness about the issue of sustainable development We first introduced the Damocles and Tara project to the pupils. Then we studied the Arctic's geography, their inhabitants and ecosystem (Biology and English). In physics and chemistry, they talked about their working conditions, equipments and what kind of analysis they would do. In geology, we studied the evolution of the sea ice and its consequences but also climate changes of the past, the influence of climate on human history and the evidences of global warming nowadays (the pupils had to find information and to make a presentation about different climate events that could be evidence of global warming). A man who works on a research boat for a French national organization came in our class and was able to present his work, the conditions of life on board and to answer the pupils' questions. This is a quick summary of our work. If you need any additional information before the GIFT, please contact me at: sophie.jayer@neuf.fr or Sophie Jayer 61 A route de Paris 78550 Bazainville 0033 (0)1 34 87 61 06 0033 (0)6 20 53 84 65 (mobile) Our group teaches at Emilie de Breteuil High School In Montigny le Bretonneux, 30 km southwest of Paris Lycée Emilie de

  16. Development of an advanced regional climate-ecosystem model for Arctic applications

    NASA Astrophysics Data System (ADS)

    Chaudhary, Nitin; Smith, Benjamin; Miller, Paul

    2013-04-01

    Cryospheric processes together with their feedbacks play a crucial role in determining rates and patterns of future warming over high-latitude regions. Cryospheric processes including permafrost as well as peatland and associated vegetation, hydrological and biogeochemical dynamics are not well represented in land surface schemes (LSS) of most climate models. As a step in this direction, we describe a scheme to include the coupled dynamics of vegetation, hydrology and peat accumulation under climate forcing within a detailed vegetation dynamics-biogeochemistry model, LPJ GUESS (Smith et al. 2001; Miller et al., in preparation). In the first step, a one-dimensional (1D) landscape scale peat accumulation and two dimensional (2D) micro-topographical models have been developed. For the parameterisation and validation of these models, good quality datasets are being used which are collected at various locations around the Arctic. Building on these, a three-dimensional (3D) scheme will be incorporated in a version of LPJ-GUESS that already includes patch-scale vegetation dynamics and soil carbon cycling, as well as a one-dimensional hydrology scheme. The patches in the 3D model will be treated as adjacent micro-patches in a grid and depending on underlying micro-topography water will flow from higher to lower patches. The 2D and 3D models will help in simulating hummock and hollow structure which is typical for Northern peatlands based on the cyclic regeneration theory (von Post and Sernander, 1910). The resulting models will be incorporated within the biospheric component of a regional climate-ecosystem model, RCA-GUESS (Smith et al., 2010) and used to investigate feedbacks related to the dynamics of peatlands, permafrost and emissions of the greenhouse gases, mainly CO2 and CH4 across the Arctic region. References- Smith B, Prentice IC, and Skyes MT. 2001. Representation of vegetation dynamics in modelling of European ecosystems: comparison of two contrasting

  17. Simulating the effects of climate change and climate variability on carbon dynamics in Arctic tundra

    NASA Astrophysics Data System (ADS)

    Stieglitz, Marc; Giblin, Anne; Hobbie, John; Williams, Matthew; Kling, George

    2000-12-01

    Through a simple modeling exercise, three mechanisms have been identified, each operating at a different timescale, that may govern carbon dynamics in Arctic tundra regions and partially explain observed CO2 flux variability. At short timescales the biosphere reacts to meteorological forcing. Drier conditions are associated with aerobic soil decomposition, a large CO2efflux, and a net ecosystem loss of carbon. Cooler and moister conditions favor slower anaerobic decomposition in soils, good growing conditions, and terrestrial carbon sequestration. At intermediate timescales, periods of terrestrial carbon loss are directly linked to periods of carbon sequestration by the ability of the ecosystem to retain labile nitrogen. Labile nitrogen released to the soil during periods when the tundra is a source of carbon (soil respiration > net primary productivity) is retained within the ecosystem and accessed during periods when carbon sequestration is favored (net primary productivity > soil respiration). Finally, the ability of vegetation to respond to long-term changes in soil nutrient status via changes in leaf nitrogen and leaf area index modulates this dynamic at intermediate to long timescales.

  18. Light treatment improves sleep quality and negative affectiveness in high arctic residents during winter.

    PubMed

    Paul, Michel A; Love, Ryan J; Hawton, Andrea; Brett, Kaighley; McCreary, Donald R; Arendt, Josephine

    2015-01-01

    The seasonal extremes of photoperiod in the high Arctic place particular strain on the human circadian system, which leads to trouble sleeping and increased feelings of negative affect in the winter months. To qualify for our study, potential participants had to have been at Canadian Forces Station (CFS) Alert (82° 30' 00″ N) for at least 2 weeks. Subjects filled out questionnaires regarding sleep difficulty, psychological well-being and mood and wore Actigraphs to obtain objective sleep data. Saliva was collected at regular intervals on two occasions, 2 weeks apart, to measure melatonin and assess melatonin onset. Individuals with a melatonin rhythm that was in disaccord with their sleep schedule were given individualized daily light treatment interventions based on their pretreatment salivary melatonin profile. The light treatment prescribed to seven of the twelve subjects was effective in improving sleep quality both subjectively, based on questionnaire results, and objectively, based on the actigraphic data. The treatment also caused a significant reduction in negative affect among the participants. Since the treatment is noninvasive and has minimal associated side effects, our results support the use of the light visors at CFS Alert and other northern outposts during the winter for individuals who are experiencing sleep difficulty or low mood. PMID:25580574

  19. McCall Glacier record of Arctic climate change: Interpreting a northern Alaska ice core with regional water isotopes

    NASA Astrophysics Data System (ADS)

    Klein, E. S.; Nolan, M.; McConnell, J.; Sigl, M.; Cherry, J.; Young, J.; Welker, J. M.

    2016-01-01

    We explored modern precipitation and ice core isotope ratios to better understand both modern and paleo climate in the Arctic. Paleoclimate reconstructions require an understanding of how modern synoptic climate influences proxies used in those reconstructions, such as water isotopes. Therefore we measured periodic precipitation samples at Toolik Lake Field Station (Toolik) in the northern foothills of the Brooks Range in the Alaskan Arctic to determine δ18O and δ2H. We applied this multi-decadal local precipitation δ18O/temperature regression to ∼65 years of McCall Glacier (also in the Brooks Range) ice core isotope measurements and found an increase in reconstructed temperatures over the late-20th and early-21st centuries. We also show that the McCall Glacier δ18O isotope record is negatively correlated with the winter bidecadal North Pacific Index (NPI) climate oscillation. McCall Glacier deuterium excess (d-excess, δ2H - 8*δ18O) values display a bidecadal periodicity coherent with the NPI and suggest shifts from more southwestern Bering Sea moisture sources with less sea ice (lower d-excess values) to more northern Arctic Ocean moisture sources with more sea ice (higher d-excess values). Northern ice covered Arctic Ocean McCall Glacier moisture sources are associated with weak Aleutian Low (AL) circulation patterns and the southern moisture sources with strong AL patterns. Ice core d-excess values significantly decrease over the record, coincident with warmer temperatures and a significant reduction in Alaska sea ice concentration, which suggests that ice free northern ocean waters are increasingly serving as terrestrial precipitation moisture sources; a concept recently proposed by modeling studies and also present in Greenland ice core d-excess values during previous transitions to warm periods. This study also shows the efficacy and importance of using ice cores from Arctic valley glaciers in paleoclimate reconstructions.

  20. Chemistry and dynamics of the Arctic winter 2015/2016: Simulations with the Chemistry-Climate Model EMAC

    NASA Astrophysics Data System (ADS)

    Khosrawi, Farahnaz; Kirner, Ole; Sinnhuber, Bjoern-Martin; Ruhnke, Roland; Hoepfner, Michael; Woiwode, Wolfgang; Oelhaf, Hermann; Santee, Michelle L.; Manney, Gloria L.; Froidevaux, Lucien; Murtagh, Donal; Braesicke, Peter

    2016-04-01

    Model simulations of the Arctic winter 2015/2016 were performed with the atmospheric chemistry-climate model ECHAM5/MESSy Atmospheric Chemistry (EMAC) for the POLSTRACC (Polar Stratosphere in a Changing Climate) project. The POLSTRACC project is a HALO mission (High Altitude and LOng Range Research Aircraft) that aims to investigate the structure, composition and evolution of the Arctic Upper Troposphere Lower Stratosphere (UTLS) in a changing climate. Especially, the chemical and physical processes involved in Arctic stratospheric ozone depletion, transport and mixing processes in the UTLS at high latitudes, polar stratospheric clouds as well as cirrus clouds are investigated. The model simulations were performed with a resolution of T42L90, corresponding to a quadratic Gaussian grid of approximately 2.8°× 2.8° degrees in latitude and longitude, and 90 vertical layers from the surface up to 0.01 hPa (approx. 80 km). A Newtonian relaxation technique of the prognostic variables temperature, vorticity, divergence and surface pressure towards ECMWF data was applied above the boundary layer and below 10 hPa, in order to nudge the model dynamics towards the observed meteorology. During the Arctic winter 2015/2016 a stable vortex formed in early December, with a cold pool where temperatures reached below the Nitric Acid Trihydrate (NAT) existence temperature of 195 K, thus allowing Polar Stratospheric Clouds (PSCs) to form. The early winter has been exceptionally cold and satellite observations indicate that sedimenting PSC particles have lead to denitrification as well as dehydration of stratospheric layers. In this presentation an overview of the chemistry and dynamics of the Arctic winter 2015/2016 as simulated with EMAC will be given and comparisons to satellite observations such as e.g. Aura/MLS and Odin/SMR will be shown.

  1. Sensitivity of permafrost carbon release to past climate change in Arctic Alaska

    NASA Astrophysics Data System (ADS)

    Gaglioti, B.; Mann, D. H.; Wooller, M. J.; Jones, B. M.; Farquharson, L. M.; Pohlman, J.

    2015-12-01

    Warming may cause arctic permafrost to thaw and release large stores of carbon (C) downstream and into the atmosphere. Documenting how permafrost-C release responded to prehistoric warming events can help determine its sensitivity to future climate change. We did this by first quantifying past climate change in Arctic Alaska over the last 15,000 years using oxygen isotope ratios in ancient wood cellulose, which is a proxy for summer temperatures and moisture sources. We then used radiocarbon (14C) age-offsets in lake sediment to determine how much permafrost C was being released over this same time period. A 14C age-offset is the difference between the true age of deposition determined by the 14C ages of delicate, terrestrial plant remains and the age of bulk sediment from the same stratigraphic layer. This bulk sediment contains ancient C derived from permafrost in the lake's watershed. Shifts in the magnitude of the age-offset over time provide a proxy for changes in the relative amount of permafrost C being released. Today, the age-offset in our study lake is 2,000 calibrated years before present (cal yr BP), which is the lowest it has been over the last 15,000 years. During the warmer-than-present, Bølling-Allerød period (BA; 14,700-12,900 cal yr BP), and the Holocene Thermal Maximum (HTM; 11,700-8,500 cal yr BP), the age offset reached 4,000-6,000 cal yr, indicating large inputs of ancient C to the lake via permafrost thaw. This enhanced input of ancient C was interrupted during the cold and dry Younger Dryas interval (YD; 12,900-11,700 cal yr BP). Interestingly, age-offsets during the YD were similar to today's, suggesting that the insulating peat layer now covering much of the LOP watershed is stabilizing permafrost C in the face of recent warming. However, this buffering capacity has a limit, and judging by the heightened influx of permafrost C during the HTM, this limit may be reached if summer temperatures warm a further 2-3°C. Temperature and

  2. Paradoxical cold conditions during the medieval climate anomaly in the Western Arctic

    PubMed Central

    Jomelli, Vincent; Lane, Timothy; Favier, Vincent; Masson-Delmotte, Valerie; Swingedouw, Didier; Rinterknecht, Vincent; Schimmelpfennig, Irene; Brunstein, Daniel; Verfaillie, Deborah; Adamson, Kathryn; Leanni, Laëtitia; Mokadem, Fatima; Aumaître, Georges; Bourlès, Didier L.; Keddadouche, Karim

    2016-01-01

    In the Northern Hemisphere, most mountain glaciers experienced their largest extent in the last millennium during the Little Ice Age (1450 to 1850 CE, LIA), a period marked by colder hemispheric temperatures than the Medieval Climate Anomaly (950 to 1250 CE, MCA), a period which coincided with glacier retreat. Here, we present a new moraine chronology based on 36Cl surface exposure dating from Lyngmarksbræen glacier, West Greenland. Consistent with other glaciers in the western Arctic, Lyngmarksbræen glacier experienced several advances during the last millennium, the first one at the end of the MCA, in ~1200 CE, was of similar amplitude to two other advances during the LIA. In the absence of any significant changes in accumulation records from South Greenland ice cores, we attribute this expansion to multi-decadal summer cooling likely driven by volcanic and/or solar forcing, and associated regional sea-ice feedbacks. Such regional multi-decadal cold conditions at the end of the MCA are neither resolved in temperature reconstructions from other parts of the Northern Hemisphere, nor captured in last millennium climate simulations. PMID:27609585

  3. Paradoxical cold conditions during the medieval climate anomaly in the Western Arctic.

    PubMed

    Jomelli, Vincent; Lane, Timothy; Favier, Vincent; Masson-Delmotte, Valerie; Swingedouw, Didier; Rinterknecht, Vincent; Schimmelpfennig, Irene; Brunstein, Daniel; Verfaillie, Deborah; Adamson, Kathryn; Leanni, Laëtitia; Mokadem, Fatima

    2016-01-01

    In the Northern Hemisphere, most mountain glaciers experienced their largest extent in the last millennium during the Little Ice Age (1450 to 1850 CE, LIA), a period marked by colder hemispheric temperatures than the Medieval Climate Anomaly (950 to 1250 CE, MCA), a period which coincided with glacier retreat. Here, we present a new moraine chronology based on (36)Cl surface exposure dating from Lyngmarksbræen glacier, West Greenland. Consistent with other glaciers in the western Arctic, Lyngmarksbræen glacier experienced several advances during the last millennium, the first one at the end of the MCA, in ~1200 CE, was of similar amplitude to two other advances during the LIA. In the absence of any significant changes in accumulation records from South Greenland ice cores, we attribute this expansion to multi-decadal summer cooling likely driven by volcanic and/or solar forcing, and associated regional sea-ice feedbacks. Such regional multi-decadal cold conditions at the end of the MCA are neither resolved in temperature reconstructions from other parts of the Northern Hemisphere, nor captured in last millennium climate simulations. PMID:27609585

  4. Polar cloud observatory at Ny-Ålesund in GRENE Arctic Climate Change Research Project

    NASA Astrophysics Data System (ADS)

    Yamanouchi, Takashi; Takano, Toshiaki; Shiobara, Masataka; Okamoto, Hajime; Koike, Makoto; Ukita, Jinro

    2016-04-01

    Cloud is one of the main processes in the climate system and especially a large feed back agent for Arctic warming amplification (Yoshimori et al., 2014). From this reason, observation of polar cloud has been emphasized and 95 GHz cloud profiling radar in high precision was established at Ny-Ålesund, Svalbard in 2013 as one of the basic infrastructure in the GRENE (Green Network of Excellence Program) Arctic Climate Change Research Project. The radar, "FALCON-A", is a FM-CW (frequency modulated continuous wave) Doppler radar, developed for Arctic use by Chiba University (PI: T. Takano) in 2012, following its prototype, "FALCON-1" which was developed in 2006 (Takano et al., 2010). The specifications of the radar are, central frequency: 94.84 GHz; antenna power: 1 W; observation height: up to 15 km; range resolution: 48 m; beam width: 0.2 degree (15 m at 5 km); Doppler width: 3.2 m/s; time interval: 10 sec, and capable of archiving high sensitivity and high spatial and time resolution. An FM-CW type radar realizes similar sensitivity with much smaller parabolic antennas separated 1.4 m from each other used for transmitting and receiving the wave. Polarized Micro-Pulse Lidar (PMPL, Sigma Space MPL-4B-IDS), which is capable to measure the backscatter and depolarization ratio, has also been deployed to Ny-Ålesund in March 2012, and now operated to perform collocated measurements with FALCON-A. Simultaneous measurement data from collocated PMPL and FALCON-A are available for synergetic analyses of cloud microphysics. Cloud mycrophysics, such as effective radius of ice particles and ice water content, are obtained from the analysis based on algorithm, which is modified for ground-based measurements from Okamoto's retrieval algorithm for satellite based cloud profiling radar and lidar (CloudSat and CALIPSO; Okamoto et al., 2010). Results of two years will be shown in the presentation. Calibration is a point to derive radar reflectivity (dBZ) from original intensity data

  5. Arctic Lake Water Temperature Patterns as Impacted by Climatic and Geomorphic Controls

    NASA Astrophysics Data System (ADS)

    Hinkel, K. M.; Sheng, Y.; Lenters, J. D.; Lyons, E. A.; Beck, R. A.

    2010-12-01

    Water temperature profile measurements were collected from 12 arctic lakes on the Arctic Coastal Plain of northern Alaska in summer 2010 as part of a network of lakes being studied. The lakes (> 1 km2) are underlain by permafrost and extend inland across some 150 km - from the Arctic coast near Barrow southward to the foothills of the Brooks Range. Regionally, lake water temperature patterns over the area are concordant and demonstrate rapid warming in late June and mid-August, with significant cooling in the second week of August. Locally, ice meltout occurs about 2-4 weeks later on lakes near the coast due to cooler temperatures and cloudy conditions associated with maritime conditions. Developed in flat marine silts, the coastal lake basins tend to be shallow (2-3 m) and of uniform depth; strong and persistent winds limit thermal stratification, and mid-summer (1 July - 15 Aug) near-surface water temperature averages 6.8°C. About 100 km further inland, in the sandy rolling topography near Atqasuk, lakes are characterized by broad shelves and deeper (2-4 m) central pools. Temperature stratification is minor (<0.5°C) and occurs only on calm, sunny days; mid-summer surface temperatures (11.6°C) are considerably warmer than lakes near the coast. Lakes here and farther south exhibit both diurnal and synoptic-scale variations in temperature. The southernmost lakes are warmest, averaging 13.0°C during the mid-summer period. Very shallow lakes (< 1 m) tend to become ice-free earlier and respond faster to air temperature forcing. Lakes in the south are developed in sand dunes and are generally 2-3 m deep. However, where the expanding lake encroaches on a dune flank at an actively eroding bluff, nearshore pools develop that can be 4-7 m deep. During calm and sunny periods lasting 7-10 days, thermal stratification occurs and the water temperature near the lake bed remains 4-7°C cooler than the surface. At one exposure, lacustrine silts were found beneath the aeolian

  6. Reconstruction of Centennial and Millennial-scale Climate and Environmental Variability during the Holocene in the Central Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Rolland, N.; Porinchu, D.; MacDonald, G.; Moser, K.

    2007-12-01

    The Arctic and sub-Arctic regions are experiencing dramatic changes in surface temperature, sea-ice extent, glacial melt, river discharge, soil carbon storage and snow cover. According to the IPCC high latitude regions are expected to warm between 4°C and 7°C over the next 100 years. The magnitude of warming and the rate at which it occurs will dwarf any previous warming episodes experienced by latitude regions over the last 11,000 years. It is critical that we improve our understanding of how the Arctic and sub-Arctic regions responded to past periods of warming, especially in light of the changes these regions will be experiencing over the next 100 years. One of the lines of evidence increasingly utilized in multi-proxy paleolimnological research is the Chironomidae (Insecta: Diptera). Also known as non-biting midge flies, chironomids are ubiquitous, frequently the most abundant insects found in freshwater ecosystems and very sensitive to environmental conditions. This research uses Chironomidae to quantitatively characterize climate and environmental conditions of the continental interior of Arctic Canada during the Holocene. Spanning four major vegetation zones (boreal forest, forest-tundra, birch tundra and herb tundra), the surface samples of 80 lakes recovered from the central Canadian Arctic were used to assess the relationship of 22 environmental variables with the chironomid distribution. Redundancy analysis (RDA) identified four variables, total Kjeldahl nitrogen (TKN), pH, summer surface water temperature (SSWT) and depth, which best explain the variance in the distribution of chironomids within these ecoregions. In order to provide new quantitative estimates of SSWT, a 1-component weighted average partial least square (WA-PLS) model was developed (r2jack = 0.76, RMSEP = 1.42°C) and applied downcore in two low arctic continental Nunavut lakes located approximately 50 km and 200 km north of modern treeline. This robust midge-inferred temperature

  7. A New Look at the Early Eocene Arctic Climate in CCSM3: Sensitivity to pCO2 and Basin Geography

    NASA Astrophysics Data System (ADS)

    Shellito, C.; Kiehl, J.; Lamarque, J.; Sloan, L.

    2007-12-01

    We present results from new Eocene climate modeling experiments that support the role of high pCO2 in maintaining Arctic warmth during the early Cenozoic. The fully-coupled NCAR Community Climate System Model (CCSM) (v.3) was employed with early Eocene geography in two experiments to test the sensitivity of climate to a large increase in pCO2 (from 2x to 8x pre-industrial pCO2). In a third experiment, we open an ocean passageway from the Eocene Arctic to the Pacific to establish the maximum sensitivity of Arctic climate to neighboring oceans, as periodic connections with adjacent ocean basins may have influenced Arctic climate at this time. To compare with the 8xCO2 scenario, we also run this open Arctic experiment at 8xCO2. In the CO2 sensitivity experiments, annual average global mean temperature rose ~3.4C with a quadrupling of pCO2, consistent with previous modeling studies. The greatest warming occurred in the Arctic Polar region, and is due in part to reduced sea ice formation in the high pCO2 experiment. Arctic surface temperatures from the high pCO2 scenario (8xCO2) agree most closely with new proxy data from the early and middle Eocene Arctic. Mean annual temperature estimates from various proxies range from ~10- 15C. Modeled Arctic temperatures range from 2-8C, and begin to approach 10C along the North American coast. While still somewhat lower than that estimated from proxies, it is important to note that in this 8xCO2 experiment, wintertime Arctic air temperatures remain mostly above freezing. Opening the Arctic to the influence of the Pacific in the third experiment has the effect of warming the average sea surface temperature in the Arctic basin by ~4C. Central Arctic ocean temperatures warm by as much as 5C to 7C. Temperatures are as high as 10C along northern Europe in the open Arctic scenario.

  8. Climate-induced changes in autumn impact spring breeding phenology and reproductive fitness in arctic ground squirrels

    NASA Astrophysics Data System (ADS)

    Sheriff, M. J.; Buck, L.; Barnes, B. M.

    2012-12-01

    Rapid climate change and shifts in seasonality can threaten the reproductive success of organisms and have negative consequences for species' range and even persistence. Focus on unidirectional effects of earlier springs and onset of reproduction do not consider effects warming may also have on autumn conditions. Shifts in the timing and duration of autumn conditions may influence spring breeding since earlier autumns may constrain offspring's winter preparation, forcing animals to breed earlier in the spring, while prolonged autumns may extend the time offspring have for winter preparation; this effect may alleviating the necessity of breeding early in spring and ultimately increase reproductive fitness. In the Arctic, warming and change in seasonality is occurring at unprecedented rates that are two to three times that of the global average. Further, rates are accelerating from about 0.15-0.17°C per decade (1961-1990) to about 0.3-0.4°C per decade. Unlike in temperate regions, arctic warming has had and is predicted to continue having major heterogeneous effects on the extent of seasonal snow cover. Future scenarios involve deeper and prolonged spring snow cover due to increased winter precipitation and frequency of spring snowstorms in some areas and reduced snow depth and earlier snowmelt with increased warming, wind, and winter precipitation falling as rain in other areas. Under both scenarios autumn is expected to become later in the year, potentially prolonging the snow free season. Snow cover is extremely important for many arctic animals controlling microclimates, defining the beginning and length of the growing season, affecting plant productivity, and allowing access to food resources. Using long-term data from two nearby populations of free-living arctic ground squirrels (AGS) that includes fine-scale information on timing of hibernation and reproduction, we found that seasonal differences in snow cover significantly influenced AGS breeding phenology

  9. DOE Final Report on Collaborative Research. Quantifying Climate Feedbacks of the Terrestrial Biosphere under Thawing Permafrost Conditions in the Arctic

    SciTech Connect

    Zhuang, Qianlai; Schlosser, C. Adam; Melillo, Jerry M.; Anthony, Katey Walter; Kicklighter, David; Gao, Xiang

    2015-11-03

    Our overall goal is to quantify the potential for threshold changes in natural emission rates of trace gases, particularly methane and carbon dioxide, from pan-arctic terrestrial systems under the spectrum of anthropogenically-forced climate warming, and the conditions under which these emissions provide a strong feedback mechanism to global climate warming. This goal is motivated under the premise that polar amplification of global climate warming will induce widespread thaw and degradation of the permafrost, and would thus cause substantial changes to the landscape of wetlands and lakes, especially thermokarst (thaw) lakes, across the Arctic. Through a suite of numerical experiments that encapsulate the fundamental processes governing methane emissions and carbon exchanges – as well as their coupling to the global climate system - we intend to test the following hypothesis in the proposed research: There exists a climate warming threshold beyond which permafrost degradation becomes widespread and stimulates large increases in methane emissions (via thermokarst lakes and poorly-drained wetland areas upon thawing permafrost along with microbial metabolic responses to higher temperatures) and increases in carbon dioxide emissions from well-drained areas. Besides changes in biogeochemistry, this threshold will also influence global energy dynamics through effects on surface albedo, evapotranspiration and water vapor. These changes would outweigh any increased uptake of carbon (e.g. from peatlands and higher plant photosynthesis) and would result in a strong, positive feedback to global climate warming.

  10. Model estimates of climate controls on pan-Arctic wetland methane emissions

    NASA Astrophysics Data System (ADS)

    Chen, X.; Bohn, T. J.; Lettenmaier, D. P.

    2015-04-01

    Climate factors including soil temperature and moisture, incident solar radiation, and atmospheric carbon dioxide concentration are important environmental controls on methane (CH4) emissions from northern wetlands. We investigated the spatio-temporal distributions of the influence of these factors on northern high latitude wetland CH4 emissions using an enhanced version of the Variable Infiltration Capacity (VIC) land surface model. We simulated CH4 emissions from wetlands across the pan-Arctic domain over the period 1948-2006, yielding annual average emissions of 35.1 ± 6.7 Tg CH4 yr-1 for the period 1997-2006. We characterized historical sensitivities to air temperature, precipitation, incident long- and short-wave radiation, and atmospheric [CO2] as a function of average summer air temperature and precipitation. Emissions from relatively warm and dry wetlands in the southern (permafrost-free) portion of the domain were positively correlated with precipitation and negatively correlated with air temperature, while emissions from wetter and colder wetlands further north (permafrost) were positively correlated with air temperature. Over the entire period 1948-2006, our reconstructed CH4 emissions increased by 20%, over 90% of which can be attributed to climate change. An increasing trend in summer air temperature explained the majority of the climate-related variance. We estimated future emissions in response to 21st century warming as predicted by CMIP5 model projections to result in end of century CH4 emissions 42% higher than our reconstructed 1997-2006 emissions, accompanied by the northward migration of warmer- and drier-than optimal conditions for CH4 emissions, implying a reduced role for temperature in driving future increases in emissions.

  11. Not Just the 8.2 event: Dynamic Early Holocene Climate in Arctic Canada

    NASA Astrophysics Data System (ADS)

    Axford, Y.; Briner, J. P.; Miller, G. H.; Francis, D. R.

    2006-12-01

    Temperature reconstructions from a lake in the eastern Canadian Arctic indicate that peak warmth in the early Holocene was interrupted by two abrupt, short-lived temperature reversals at ~9.l and ~8.5 ka. Summer temperatures at Lake CF8, Baffin Island (~500 km west of Greenland) are inferred from subfossil midge (Chironomidae) assemblages. Our results indicate that the site, like others on Baffin Island, experienced exceptionally warm summers (almost 5°C warmer than present) through much of the early Holocene, presumably in response to enhanced summer insolation. After 1000 years of very warm, stable climate, warmth was interrupted by two discrete cold reversals at ~9.1 and ~8.5 ka, during which multiple cold-stenothermous midge taxa appeared in the lake and summer temperatures dropped more than 3°C. These two clearly-defined reversals, well beyond the range of background variability, were of similar amplitude and duration, and were separated by several centuries of near-peak warmth. The only Holocene events of comparable amplitude at this site are the rapid onset of Holocene warmth, and the more gradual Neoglacial cooling after 8 ka. Abrupt cooling events over the Baffin region are consistent with model simulations of the impacts of freshwater outbursts into the Labrador Sea, such as the Lake Agassiz outburst flood that occurred ~8.4 ka. That there are two discrete events recorded at this site indicates that the "8.2 event" was not uniquely significant in this region; rather, the period between approximately ~9.2 and 8 ka was characterized by repeated climate fluctuations forced by multiple outburst floods or other mechanisms. Thus global correlations among paleoclimate records need not assume that climate perturbations during this time period necessarily correlate with the draining of Lake Agassiz or the 8.2 ka cooling in central Greenland.

  12. Using the Arts as a Bridge to Public Understanding of Data-Intensive Earth Science Research through Climate Prisms: The Arctic

    NASA Astrophysics Data System (ADS)

    Samsel, F.; Deck, L. T.; Wilson, C. J.; Rodriguez-Acosta, M.

    2015-12-01

    An ever-growing body of research in Informal Science Education is showing that the arts contribute greatly to engaging the free-choice science learner. This kind of learning goes on outside of the classroom, notably in science centers and museums, where novel, experiential approaches can be piloted. A new exhibit, Climate Prisms: The Arctic, is being mounted by a team of artists and scientists at the Bradbury Science Museum of Los Alamos National Laboratory. It presents the pipeline from collecting soil samples in the Arctic to analyzing them in the labs to the statistical analysis of the findings and on to the input into the climate model, using prisms of art: visual art, poetry, scientific text, information graphics, field imagery and others. The presentation encourages users to view Arctic science through these different lenses. Each person plots their own path, moving through the content at the pace and level that best enables them to engage with the material. With the entry points through multiple artistic voices, learners hearts and feelings are directly reached, building primarily affective connections and then curiosity, rather than cognitive. The project itself is a large display screen driven by a touch interface designed for individual or small group viewing. Content paths are determined by an underlying system of tags, levels, content categories and related research areas. A screen shows a set of images. Each image can be accessed to provide image-specific information or can be a launching pad for a new set of related content and images that allows the user to continue on their exploration journey. Each person, each time they visit, creates a unique path through over 2000 pieces of content according to the unique set of learning assets and interests they bring with them at that visit. Embedded assessment will log basic demographics and each individual foray through the content. These assessments will be analyzed to explore trends of use and drive

  13. How fast is Arctic climate really changing? An insight from recent past, present day and near future coupled model simulations

    NASA Astrophysics Data System (ADS)

    Koenigk, Torben; Brodeau, Laurent

    2016-04-01

    Three quasi-equilibrium simulations using constant greenhouse gas forcing corresponding to years 2000, 2015 and 2030 have been performed with the global coupled model EC-Earth in order to analyze recent past and possible near future changes in the Arctic climate. The model simulations indicate an accelerated warming and ice extent reduction in the Arctic in near future conditions compared to the recent past. Both Arctic warming and sea ice reduction are closely linked to the increase of ocean heat transport into the Arctic, particularly through the Barents Sea Opening. Decadal variations of Arctic sea ice extent and ice volume are of the same order of magnitude as the observed ice extent reductions in the last 30 years and are dominated by the variability of the ocean heat transports through the Barents Sea Opening and the Bering Strait. Despite a general warming of mid and high northern latitudes, a substantial cooling is found in the subpolar gyre of the North Atlantic in the near future simulation. This cooling is related to a strong reduction in the AMOC, which is mainly caused by reduced deep water formation in the Labrador Sea. The observed trend towards a more negative phase of the North Atlantic Oscillation (NAO) and the observed linkage between autumn Arctic ice variations and NAO are reproduced in our model simulations for selected 30-year periods but are not robust over longer time periods. This indicates that the observed linkages between ice and NAO might not be robust in reality either, and that the observational time period is still too short to reliably separate the trend from the natural variability.

  14. Adaptation strategies to climate change in the Arctic: a global patchwork of reactive community-scale initiatives

    NASA Astrophysics Data System (ADS)

    Loboda, Tatiana V.

    2014-11-01

    Arctic regions have experienced and will continue to experience the greatest rates of warming compared to any other region of the world. The people living in the Arctic are considered among most vulnerable to the impacts of environmental change ranging from decline in natural resources to increasing mental health concerns (IPCC 2014 Climate Change 2014: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (Cambridge: Cambridge University Press)). A meta-analysis study by Ford et al (2014 Environ. Res. Lett. 9 104005) has assessed the volume, scope and geographic distribution of reported in the English language peer-reviewed literature initiatives for adaptation to climate change in the Arctic. Their analysis highlights the reactive nature of the adopted policies with a strong emphasis on local and community-level policies mostly targeting indigenous population in Canada and Alaska. The study raises concerns about the lack of monitoring and evaluation mechanism to track the success rate of the existing policies and the need for long-term strategic planning in adaption policies spanning international boundaries and including all groups of population.

  15. Influence of Climate Warming on Arctic Mammals? New Insights from Ancient DNA Studies of the Collared Lemming Dicrostonyx torquatus

    PubMed Central

    Prost, Stefan; Smirnov, Nickolay; Fedorov, Vadim B.; Sommer, Robert S.; Stiller, Mathias; Nagel, Doris; Knapp, Michael; Hofreiter, Michael

    2010-01-01

    Background Global temperature increased by approximately half a degree (Celsius) within the last 150 years. Even this moderate warming had major impacts on Earth's ecological and biological systems, especially in the Arctic where the magnitude of abiotic changes even exceeds those in temperate and tropical biomes. Therefore, understanding the biological consequences of climate change on high latitudes is of critical importance for future conservation of the species living in this habitat. The past 25,000 years can be used as a model for such changes, as they were marked by prominent climatic changes that influenced geographical distribution, demographic history and pattern of genetic variation of many extant species. We sequenced ancient and modern DNA of the collared lemming (Dicrostonyx torquatus), which is a key species of the arctic biota, from a single site (Pymva Shor, Northern Pre Urals, Russia) to see if climate warming events after the Last Glacial Maximum had detectable effects on the genetic variation of this arctic rodent species, which is strongly associated with a cold and dry climate. Results Using three dimensional network reconstructions we found a dramatic decline in genetic diversity following the LGM. Model-based approaches such as Approximate Bayesian Computation and Markov Chain Monte Carlo based Bayesian inference show that there is evidence for a population decline in the collared lemming following the LGM, with the population size dropping to a minimum during the Greenland Interstadial 1 (Bølling/Allerød) warming phase at 14.5 kyrs BP. Conclusion Our results show that previous climate warming events had a strong influence on genetic diversity and population size of collared lemmings. Due to its already severely compromised genetic diversity a similar population reduction as a result of the predicted future climate change could completely abolish the remaining genetic diversity in this population. Local population extinctions of collared

  16. Arctic Climate Forcing Observations to Improve Earth System Models: Measurements at High Frequency, Fine Spatial Resolution, and Climatically Relevant Spatial Scales with the use of the Recently Deployed NGEE-Arctic Tram

    NASA Astrophysics Data System (ADS)

    Curtis, J. B.; Serbin, S.; Dafflon, B.; Raz Yaseef, N.; Torn, M. S.; Cook, P. J.; Lewin, K. F.; Wullschleger, S. D.

    2014-12-01

    In order to improve the representation of the land surface and subsurface properties and their associated feedbacks with climate forcings, climate change, and drivers in Earth System Models (ESMs), detailed observations need to be made at climatically relevant spatial and temporal scales. Pan-Arctic spatial heterogeneity and temporal variation present major challenges to the current generation of ESMs. To enable highly spatially resolved and high temporal frequency measurements for the independent validation of modeled energy and greenhouse gas surface fluxes at core to intermediate scales, we have developed, tested, and deployed an automated observational platform, the Next Generation Ecosystem Experiment (NGEE)-Arctic Tram. The NGEE-Arctic Tram, installed on the Barrow Environmental Observatory (BEO) near Barrow, AK in mid May 2014, consists of 65 meters of elevated track and a fully automated cart carrying a suite of radiation and remote sensing instrumentation. The tram transect is located within the NGEE eddy covariance tower footprint to help better understand the relative contribution of different landforms (e.g. low center vs high center polygonal tundra and associated vegetation) to the overall energy budget of the footprint. Electrical resistivity tomography (ERT), soil moisture, and soil temperature sensors are acquired autonomously and co-located with the tram to link subsurface properties with surface observations. To complement the high frequency and fine spatial resolution of the tram, during the summer field seasons of 2013 and 2014 a portable version of the NGEE-Arctic Tram (also know as the portable energy pole or PEP); was used to characterize surface albedo, NDVI, surface temperature, and photosynthetically active radiation (PAR) across two ~500 m BEO transects co-located with subsurface ERT and ground penetrating radar (GPR) measurements. In addition, a ~ 3 Km transect across three drained thaw-lake basins (DTLB) of different climate

  17. Dynamics of Arctic and Sub-Arctic Climate and Atmospheric Circulation: Diagnosis of Mechanisms and Model Biases Using data Assimilation

    SciTech Connect

    Sumant Nigam

    2013-02-05

    These five publications are summarized: Key role of the Atlantic Multidecadal Oscillation in 20th century drought and wet periods over the Great Plains; A Sub-Seasonal Teleconnection Analysis: PNA Development and Its Relationship to the NAO; AMO's Structure and Climate Footprint in Observations and IPCC AR5 Climate Simulations; The Atlantic Multidecadal Oscillation in 20th Century Climate Simulations: Uneven Progress from CMIP3 to CMIP5; and Tropical Atlantic Biases in CCSM4.

  18. Identifying the critical climatic time window that affects trait expression.

    PubMed

    van de Pol, Martijn; Cockburn, Andrew

    2011-05-01

    Identifying the critical time window during which climatic drivers affect the expression of phenological, behavioral, and demographic traits is crucial for predicting the impact of climate change on trait and population dynamics. Two widely used associative methods exist to identify critical climatic periods: sliding-window models and recursive operators in which the memory of past weather fades over time. Both approaches have different strong points, which we combine here into a single method. Our method uses flexible functions to differentially weight past weather, which can reflect competing hypotheses about time lags and the relative importance of recent and past weather for trait expression. Using a 22-year data set, we illustrate that the climatic window identified by our new method explains more of the phenological variation in a sexually selected trait than existing approaches. Our new method thus helps to better identify the critical time window and the causes of trait response to environmental variability. PMID:21508615

  19. The ocean's role in polar climate change: asymmetric Arctic and Antarctic responses to greenhouse gas and ozone forcing.

    PubMed

    Marshall, John; Armour, Kyle C; Scott, Jeffery R; Kostov, Yavor; Hausmann, Ute; Ferreira, David; Shepherd, Theodore G; Bitz, Cecilia M

    2014-07-13

    In recent decades, the Arctic has been warming and sea ice disappearing. By contrast, the Southern Ocean around Antarctica has been (mainly) cooling and sea-ice extent growing. We argue here that interhemispheric asymmetries in the mean ocean circulation, with sinking in the northern North Atlantic and upwelling around Antarctica, strongly influence the sea-surface temperature (SST) response to anthropogenic greenhouse gas (GHG) forcing, accelerating warming in the Arctic while delaying it in the Antarctic. Furthermore, while the amplitude of GHG forcing has been similar at the poles, significant ozone depletion only occurs over Antarctica. We suggest that the initial response of SST around Antarctica to ozone depletion is one of cooling and only later adds to the GHG-induced warming trend as upwelling of sub-surface warm water associated with stronger surface westerlies impacts surface properties. We organize our discussion around 'climate response functions' (CRFs), i.e. the response of the climate to 'step' changes in anthropogenic forcing in which GHG and/or ozone-hole forcing is abruptly turned on and the transient response of the climate revealed and studied. Convolutions of known or postulated GHG and ozone-hole forcing functions with their respective CRFs then yield the transient forced SST response (implied by linear response theory), providing a context for discussion of the differing warming/cooling trends in the Arctic and Antarctic. We speculate that the period through which we are now passing may be one in which the delayed warming of SST associated with GHG forcing around Antarctica is largely cancelled by the cooling effects associated with the ozone hole. By mid-century, however, ozone-hole effects may instead be adding to GHG warming around Antarctica but with diminished amplitude as the ozone hole heals. The Arctic, meanwhile, responding to GHG forcing but in a manner amplified by ocean heat transport, may continue to warm at an accelerating rate

  20. A closer investigation of associations between Autumn Arctic sea ice and central and east Eurasian winter climate

    NASA Astrophysics Data System (ADS)

    Wang, Shaoyin; Liu, Jiping

    2016-04-01

    Whether recent Arctic sea ice loss is responsible for recent severe winters over mid-latitude continents has emerged as a major debate among climate scientists owing to short records of observations and large internal variability in mid- and high-latitudes. In this study, we divide the evolution of autumn Arctic sea ice extent during 1979-2014 into three epochs, 1979-1986 (high), 1987-2006 (moderate) and 2007-2014 (low), using a regime shift identification method. We then compare the associations between autumn Arctic sea ice and winter climate anomalies over central and eastern Eurasia for the three epochs with focus not only on the mean state, but also the extreme events. The results show robust and detectable signals of sea ice loss in weather and climate over western Siberia and East Asia. For the mean state, anomalous low sea ice extent is associated with a strengthening of the Siberian high pressure, a weakening of westerly winds over north Asia, leading to cold anomalies in central Asia and northern China. For the extreme events, the latitude (speed) of the jet stream shifts southward (reduces), the wave extent amplifies, blocking high events increase over Ural Mountains, leading to increased frequency of cold air outbreaks extending from central Asia to northeast China. These associations bear a high degree of similarity to the observed atmospheric anomalies during the low sea ice epoch. By contrast, the patterns of atmospheric anomalies for the high sea ice epoch are different from those congruent with sea ice variability, which is related to the persistent negative phase of the Arctic Oscillation. We also found that the ENSO plays a minor role in the determination of the observed atmospheric anomalies for the three epochs. Support for these observational analysis is largely corroborated by independent atmospheric model simulations.

  1. The ocean's role in polar climate change: asymmetric Arctic and Antarctic responses to greenhouse gas and ozone forcing

    PubMed Central

    Marshall, John; Armour, Kyle C.; Scott, Jeffery R.; Kostov, Yavor; Hausmann, Ute; Ferreira, David; Shepherd, Theodore G.; Bitz, Cecilia M.

    2014-01-01

    In recent decades, the Arctic has been warming and sea ice disappearing. By contrast, the Southern Ocean around Antarctica has been (mainly) cooling and sea-ice extent growing. We argue here that interhemispheric asymmetries in the mean ocean circulation, with sinking in the northern North Atlantic and upwelling around Antarctica, strongly influence the sea-surface temperature (SST) response to anthropogenic greenhouse gas (GHG) forcing, accelerating warming in the Arctic while delaying it in the Antarctic. Furthermore, while the amplitude of GHG forcing has been similar at the poles, significant ozone depletion only occurs over Antarctica. We suggest that the initial response of SST around Antarctica to ozone depletion is one of cooling and only later adds to the GHG-induced warming trend as upwelling of sub-surface warm water associated with stronger surface westerlies impacts surface properties. We organize our discussion around ‘climate response functions’ (CRFs), i.e. the response of the climate to ‘step’ changes in anthropogenic forcing in which GHG and/or ozone-hole forcing is abruptly turned on and the transient response of the climate revealed and studied. Convolutions of known or postulated GHG and ozone-hole forcing functions with their respective CRFs then yield the transient forced SST response (implied by linear response theory), providing a context for discussion of the differing warming/cooling trends in the Arctic and Antarctic. We speculate that the period through which we are now passing may be one in which the delayed warming of SST associated with GHG forcing around Antarctica is largely cancelled by the cooling effects associated with the ozone hole. By mid-century, however, ozone-hole effects may instead be adding to GHG warming around Antarctica but with diminished amplitude as the ozone hole heals. The Arctic, meanwhile, responding to GHG forcing but in a manner amplified by ocean heat transport, may continue to warm at an

  2. Climate Change: Potential Affect on Pesticide Application for Vector Control

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Global climate change has and will in the future contribute to the global burden of vector-borne disease by affecting the spatial and tempral distribution of disease. These changes in disease distributions are a direct result of altering the ecology of immature and adult habitats of insect vectors....

  3. The Svalbard REU Program: Undergraduates Pursuing Arctic Climate Change Research on Svalbard, Norway

    NASA Astrophysics Data System (ADS)

    Roof, S.; Werner, A.

    2007-12-01

    The Svalbard Research Experiences for Undergraduates (REU) program sponsored by the Arctic Natural Sciences Program of the National Science Foundation has been successfully providing international field research experiences since 2004. Each year, 7-9 undergraduate students have participated in 4-5 weeks of glacial geology and climate change fieldwork on Spitsbergen in the Svalbard archipelago in the North Atlantic (76- 80° N lat.). While we continue to learn new and better ways to run our program, we have learned specific management and pedagogical strategies that allow us to streamline our logistics and to provide genuine, meaningful research opportunities to undergraduate students. We select student participants after extensive nationwide advertising and recruiting. Even before applying to the program, students understand that they will be doing meaningful climate change science, will take charge of their own project, and will be expected to continue their research at their home institution. We look for a strong commitment of support from a student's advisor at their home institution before accepting students into our program. We present clear information, including participant responsibilities, potential risks and hazards, application procedures, equipment needed, etc on our program website. The website also provides relevant research papers and data and results from previous years, so potential participants can see how their efforts will contribute to growing body of knowledge. New participants meet with the previous years' participants at a professional meeting (our "REUnion") before they start their field experience. During fieldwork, students are expected to develop research questions and test their own hypotheses while providing and responding to peer feedback. Professional assessment by an independent expert provides us with feedback that helps us improve logistical procedures and shape our educational strategies. The assessment also shows us how

  4. Spring melt ponds drive Arctic September ice at past, present and future climates in coupled climate simulation

    NASA Astrophysics Data System (ADS)

    Schroeder, David; Feltham, Danny; Rae, Jamie; Flocco, Daniela; Ridley, Jeff; Blockley, Edd

    2016-04-01

    Stand-alone sea ice simulations with a physical based melt pond model reveal a strong correlation between the simulated spring pond fraction and the observed as well as simulated September sea ice extent for the period 1979 to 2014. This is explained by a positive feedback mechanism: more ponds reduce the albedo; a lower albedo causes more melting; more melting increases pond fraction. This feedback process is a potential reason for the acceleration of Arctic sea ice decrease in the last decade and the failure of many climate models (without an implicit pond model) to simulate the observed decrease. We implemented the Los Alamos sea ice model CICE 5 including our physical based melt pond model into the latest version of the Hadley Centre coupled climate model, HadGEM3. The model surface shortwave radiation scheme has been adjusted to account for pond fraction and depth. We performed three 55-year HadGEM3 simulations with constant external forcing for the years 1985, 2010 and 2035. In all three simulations we find a strong correlation between the April/May pond fraction and the September sea ice extent with correlation coefficients R1985 = -0.86, R2010 = -0.83 and R2035 = -0.79. Based on the correlation we can perform forecasts with remarkable skill values of S1985 = 0.50, S2010 = 0.36 and S2035 = 0.40. We calculate the skill as S = 1 - σferr2/ σref2, where σref2 is the variance of the de-trended climatology and σferr2 the forecast error variance. Altogether our three simulations cover a large range of September sea ice extent from maximum values of 8.5 million km2 for the 1985 run down to 1.5 million km2 for the 2035 run. We demonstrate that spring melt ponds are an important driver for summer ice melt and the consequent minimum ice extent for current and future climate conditions.

  5. The impact of precession changes on the Arctic climate during the last interglacial glacial transition

    NASA Astrophysics Data System (ADS)

    Khodri, Myriam; Cane, Mark A.; Kukla, George; Gavin, Joyce; Braconnot, Pascale

    2005-07-01

    Three sensitivity experiments using an Ocean Atmosphere General Circulation Model (OAGCM) are conducted to simulate the climate impact of precession. The relative contributions of components of the hydrological cycle including the albedo of Arctic sea ice, advection of atmospheric water vapor and sea surface temperature to the summer Arctic melt process are evaluated. Timing of the perihelion is varied in each experiment with meteorological spring (SP), winter (WP) and autumn (AP) perihelion corresponding to conditions at 110, 115 and 120 ky BP, respectively. Obliquity is unchanged at the 115 ky level which is lower than today. The experiments are assessed relative to the present day control, which has been shown to simulate current conditions based on observations. In the SP experiment, top of the atmosphere (TOA) insolation is weaker than today between the summer solstice and autumnal equinox. In the AP case representing the interglacial, it is less intense between vernal equinox and summer solstice but stronger during the remainder of the year. Although the incident solar radiation is reduced in summer in the SP experiment, increased melting of snow is found primarily as a result of feedbacks from the delayed seasonal cycle of hydrologic components. This is in contrast to both the WP and AP cases in which the perennial snow cover is simulated. At the time of the last glacial inception, 115 ky BP, the WP experiment shows lower insolation to the high northern latitudes in late spring and summer mainly as a result of lower obliquity than today. Dynamical ocean-atmosphere interactions in response to precession maintain the reduced sea ice melting in late spring, strengthen the annual equator-to-pole sea surface temperature (SST) gradient and increase atmospheric moisture convergence in glaciation-sensitive regions. In both the WP and AP experiments seasonal sea ice melting is weakened resulting in pronounced outgoing radiative flux at the locations of expanded sea

  6. Regional Climate Modeling over the Glaciated Regions of the Canadian High Arctic

    NASA Astrophysics Data System (ADS)

    Gready, Benjamin P.

    The Canadian Arctic Islands (CAI) contain the largest concentration of terrestrial ice outside of the continental ice sheets. Mass loss from this region has recently increased sharply due to above average summer temperatures. Thus, increasing the understanding of the mechanisms responsible for mass loss from this region is critical. Previously, Regional Climate Models (RCMs) have been utilized to estimate climatic balance over Greenland and Antarctica. This method offers the opportunity to study a full suite of climatic variables over extensive spatially distributed grids. However, there are doubts of the applicability of such models to the CAI, given the relatively complex topography of the CAI. To test RCMs in the CAI, the polar version of the regional climate model MM5 was run at high resolution over Devon Ice Cap. At low altitudes, residuals (computed through comparisons with in situ measurements) in the net radiation budget were driven primarily by residuals in net shortwave (NSW) radiation. Residuals in NSW are largely due to inaccuracies in modeled cloud cover and modeled albedo. Albedo on glaciers and ice sheets is oversimplified in Polar MM5 and its successor, the Polar version of the Weather Research and Forecast model (Polar WRF), and is an obvious place for model improvement. Subsequently, an inline parameterization of albedo for Polar WRF was developed as a function of the depth, temperature and age of snow. The parameterization was able to reproduce elevation gradients of seasonal mean albedo derived from satellite albedo measurements (MODIS MOD10A1 daily albedo), on the western slope of the Greenland Ice Sheet for three years. Feedbacks between modelled albedo and modelled surface energy budget components were identified. The shortwave radiation flux feeds back positively with changes to albedo, whereas the longwave, turbulent and ground energy fluxes all feed back negatively, with a maximum combined magnitude of two thirds of the shortwave feedback

  7. Deep lakes in the Polar Urals - unique archives for reconstructing the Quaternary climate and glacial history in the Russian Arctic

    NASA Astrophysics Data System (ADS)

    Svendsen, J.; Gyllencreutz, R.; Henriksen, M.; Lohne, O. S.; Mangerud, J.; Nazarov, D.

    2009-12-01

    A lake coring campaign in the Polar Urals is carried out within the framework of the Norwegian-Russian IPY-project “The Ice Age Development and Human Settlement in Northern Eurasia” (ICEHUS). The overall aim of the project is to improve the description and understanding of the Late Quaternary environmental and climate changes in the Russian Arctic and how these changes may have affected the early human occupation. In order to obtain a continuous record of climate variability back in time seismic records and sediment cores have been collected from selected mountain lakes. The summer of 2009 we cored two lakes situated near the water shed in the interior northernmost Urals. Seismic profiles show that both these glacially eroded basins contain thick sequences of Quaternary sediments. The thickest strata were found in Bolshoye Shuchye, the largest and deepest lake in the Ural Mountains. This lake is 13 km long and 140 m deep and contains more than 130 m of acoustically laminated sediments. These strata probably accumulated over a rather long time span, possibly covering several interglacial-glacial cycles. Up to 24 m long cores were obtained from the lake floors. We anticipate that they will provide unique high resolution records of the climate and glacial history during the last Ice Age. The seismic records and the sediment cores will form a well-founded basis for assessing the potential and possibilities to core also the deeper strata that could not be reached with the applied coring equipment. In view of the obtained results from the investigated basins, as well as other geological and geochronological data from the surrounding areas, we find it highly unlikely that any glaciers extended into these lakes during the Last Glacial Maximum (LGM), supporting our current hypothesis that the local glaciers in the Polar Urals remained small during the LGM. Our observations indicate that the mountain valleys have been essentially ice free since Marine Isotope Stage 4, at

  8. Arctic and boreal ecosystems of western North America as components of the climate system

    USGS Publications Warehouse

    Chapin, F. S., III; McGuire, A.D.; Randerson, J.; Pielke, R., Sr.; Baldocchi, D.; Hobbie, S.E.; Roulet, Nigel; Eugster, W.; Kasischke, E.; Rastetter, E.B.; Zimov, S.A.; Running, S.W.

    2000-01-01

    Synthesis of results from several Arctic and boreal research programmes provides evidence for the strong role of high-latitude ecosystems in the climate system. Average surface air temperature has increased 0.3??C per decade during the twentieth century in the western North American Arctic and boreal forest zones. Precipitation has also increased, but changes in soil moisture are uncertain. Disturbance rates have increased in the boreal forest; for example, there has been a doubling of the area burned in North America in the past 20 years. The disturbance regime in tundra may not have changed. Tundra has a 3-6-fold higher winter albedo than boreal forest, but summer albedo and energy partitioning differ more strongly among ecosystems within either tundra or boreal forest than between these two biomes. This indicates a need to improve our understanding of vegetation dynamics within, as well as between, biomes. If regional surface warming were to continue, changes in albedo and energy absorption would likely act as a positive feedback to regional warming due to earlier melting of snow and, over the long term, the northward movement of treeline. Surface drying and a change in dominance from mosses to vascular plants would also enhance sensible heat flux and regional warming in tundra. In the boreal forest of western North America, deciduous forests have twice the albedo of conifer forests in both winter and summer, 50-80% higher evapotranspiration, and therefore only 30-50% of the sensible heat flux of conifers in summer. Therefore, a warming-induced increase in fire frequency that increased the proportion of deciduous forests in the landscape, would act as a negative feedback to regional warming. Changes in thermokarst and the aerial extent of wetlands, lakes, and ponds would alter high-latitude methane flux. There is currently a wide discrepancy among estimates of the size and direction of CO2 flux between high-latitude ecosystems and the atmosphere. These

  9. The ocean's role in polar climate change: asymmetric Arctic and Antarctic responses to greenhouse gas and ozone forcing. (Invited)

    NASA Astrophysics Data System (ADS)

    Marshall, J.; Ferreira, D.; Bitz, C. M.

    2013-12-01

    In recent decades the Arctic has been warming with sea ice disappearing. But the Antarctic has been (mainly) cooling and sea ice is growing. We argue here that inter-hemispheric asymmetries in the mean ocean circulation, with sinking in the northern north Atlantic and upwelling around Antarctica, strongly influences the surface response to GHG forcing, accelerating warming in the Arctic and delaying it in the Antarctic. Moreover, while GHG forcing has been qualitatively similar at the poles, ozone depletion only occurs in the Antarctic. The coupled atmosphere-ocean response to ozone depletion may further help to explain the Antarctic trends. A framework is presented to quantify the processes at work built around `Climate Response Functions' for GHG and Ozone-hole forcing.

  10. Large-scale climatic patterns and area affected by mountain pine beetle in British Columbia, Canada

    NASA Astrophysics Data System (ADS)

    Macias Fauria, Marc; Johnson, E. A.

    2009-03-01

    We present evidence of high spatial synchrony in an area affected by mountain pine beetle (MPB, Dendroctonus ponderosae) across large distances in British Columbia, Canada, in a study of a spatially explicit database of an area affected by MPB-caused tree mortality for the period 1959-2002. We further show that large-scale climatic patterns (Pacific Decadal Oscillation (PDO) and, to a lesser degree, Arctic Oscillation (AO)) are strongly related to the observed MPB synchrony, and that they probably operate through controlling the frequency of extreme cold winter temperatures that affect MPB larvae survival. A smaller portion of the data's variability is linked to the onset of the two largest outbreaks in the studied period and might be attributed to dispersal from outbreak-prone areas or else to differences in microhabitat (e.g., host availability) in these regions. The onset of a warm PDO phase in 1976 favored MPB outbreaks by reducing the occurrence of extremely low winter temperatures province-wide. Likewise, the exceptionally high and persistent AO values of the late 1980s and 1990s enhanced MPB activity in the southern and northern parts of the region. Summer warmth cannot be discarded as an important agent at smaller scales.

  11. The Impact of Climate Change on Microbial Communities and Carbon Cycling in High Arctic Permafrost Soil from Spitsbergen, Northern Norway

    NASA Astrophysics Data System (ADS)

    de Leon, K. C.; Schwery, D.; Yoshikawa, K.; Christiansen, H. H.; Pearce, D.

    2014-12-01

    Permafrost-affected soils are among the most fragile ecosystems in which current microbial controls on organic matter decomposition are changing as a result of climate change. Warmer conditions in the high Arctic will lead to a deepening of the seasonal active layer of permafrost, provoking changes in microbial processes and possibly resulting in exacerbated carbon degradation under increasing anoxic conditions. The viable and non-viable fractions of the microbial community in a permafrost soil from Adventdalen, Spitsbergen, Norway were subjected to a comprehensive investigation using culture-dependent and culture-independent methods. Molecular analyses using FISH (with CTC-DAPI) and amplified rDNA restriction analysis (ARDRA) on a 257cm deep core, revealed the presence of all major microbial soil groups, with the active layer having more viable cells, and a higher microbial community diversity. Carbon dioxide (CO2) and methane (CH4) flux measurements were performed to show the amount of C stored in the sample. We demonstrated that the microbial community composition from the soil in the center of the core was most likely influenced by small scale variations in environmental conditions. Community structure showed distinct shift of presence of bacterial groups along the vertical temperature gradient profile and microbial counts and diversity was found to be highest in the surface layers, decreasing with depth. It was observed that soil properties driving microbial diversity and functional potential varied across the permafrost table. Data on the variability of CO2 and CH4 distribution described in peat structure heterogeneity are important for modeling emissions on a larger scale. Furthermore, linking microbial biomass to gas distribution may elucidate the cause of peak CO2 and CH4 and their changes in relation to environmental change and peat composition.

  12. Mid-Holocene climate transition in the Arctic: a database of multicentennial quality climate proxy data from 6 to 2 ka

    NASA Astrophysics Data System (ADS)

    Sundqvist, H. S.; Kaufman, D. S.; Balascio, N. L.

    2012-12-01

    A major goal of paleoclimatology is to reconstruct the spatial-temporal pattern of past climate changes. The spatial-temporal pattern of temperature variability reflects the dynamics of the climate system, including its response to known climate forcing mechanisms and thresholds that lead to rapid transitions. A large network of well-dated proxy climate records is needed to capture the details of past climate variability. We have embarked on major systematic compilation of previously published Holocene proxy climate records from the Arctic. The focus is on well-dated, highly resolved, continuous records that extend to at least 6 ka BP, thereby capturing the transition between the relatively warm conditions of the Holocene thermal maximum and the cooler Neoglaciation. We have identified 139 sites from north of 58° latitude where published proxy records are resolved at centennial scale (at least one value every 400 ± 200 years) and have timescales constrained by at least one radiometric age every 3000 years. We have assembled the metadata for the proxy records from all sites including information on their location, archive and proxy types, climate interpretation, quality of the record (sample resolution and geochronological control), and the data source. The database currently (August 2012) includes the numerical proxy records from most of the sites. We have also compiled the original geochronological data, with the future goal of revising the underlying age models and quantifying age uncertainties. The majority (73%) of the proxy records in the current metadatabase are from lake sediments, with the reminder from marine sediment (17%) and glacier ice (7%). Most of the paleo-temperature records (54%) are based on pollen spectra, and another 26% are based on chironomid assemblages. Many of the proxy records reflect changes in precipitation or hydrology (26%). A high proportion of the sites (35%) are from Fennoscandia, 22% are from the Canadian islands and Greenland

  13. Cloud-Scale Numerical Modeling of the Arctic Boundary Layer

    NASA Technical Reports Server (NTRS)

    Krueger, Steven K.

    1998-01-01

    The interactions between sea ice, open ocean, atmospheric radiation, and clouds over the Arctic Ocean exert a strong influence on global climate. Uncertainties in the formulation of interactive air-sea-ice processes in global climate models (GCMs) result in large differences between the Arctic, and global, climates simulated by different models. Arctic stratus clouds are not well-simulated by GCMs, yet exert a strong influence on the surface energy budget of the Arctic. Leads (channels of open water in sea ice) have significant impacts on the large-scale budgets during the Arctic winter, when they contribute about 50 percent of the surface fluxes over the Arctic Ocean, but cover only 1 to 2 percent of its area. Convective plumes generated by wide leads may penetrate the surface inversion and produce condensate that spreads up to 250 km downwind of the lead, and may significantly affect the longwave radiative fluxes at the surface and thereby the sea ice thickness. The effects of leads and boundary layer clouds must be accurately represented in climate models to allow possible feedbacks between them and the sea ice thickness. The FIRE III Arctic boundary layer clouds field program, in conjunction with the SHEBA ice camp and the ARM North Slope of Alaska and Adjacent Arctic Ocean site, will offer an unprecedented opportunity to greatly improve our ability to parameterize the important effects of leads and boundary layer clouds in GCMs.

  14. Predicting when climate-driven phenotypic change affects population dynamics.

    PubMed

    McLean, Nina; Lawson, Callum R; Leech, Dave I; van de Pol, Martijn

    2016-06-01

    Species' responses to climate change are variable and diverse, yet our understanding of how different responses (e.g. physiological, behavioural, demographic) relate and how they affect the parameters most relevant for conservation (e.g. population persistence) is lacking. Despite this, studies that observe changes in one type of response typically assume that effects on population dynamics will occur, perhaps fallaciously. We use a hierarchical framework to explain and test when impacts of climate on traits (e.g. phenology) affect demographic rates (e.g. reproduction) and in turn population dynamics. Using this conceptual framework, we distinguish four mechanisms that can prevent lower-level responses from impacting population dynamics. Testable hypotheses were identified from the literature that suggest life-history and ecological characteristics which could predict when these mechanisms are likely to be important. A quantitative example on birds illustrates how, even with limited data and without fully-parameterized population models, new insights can be gained; differences among species in the impacts of climate-driven phenological changes on population growth were not explained by the number of broods or density dependence. Our approach helps to predict the types of species in which climate sensitivities of phenotypic traits have strong demographic and population consequences, which is crucial for conservation prioritization of data-deficient species. PMID:27062059

  15. Model estimates of climate controls on pan-Arctic wetland methane emissions

    NASA Astrophysics Data System (ADS)

    Chen, X.; Bohn, T. J.; Lettenmaier, D. P.

    2015-11-01

    Climate factors including soil temperature and moisture, incident solar radiation, and atmospheric carbon dioxide concentration are important environmental controls on methane (CH4) emissions from northern wetlands. We investigated the spatiotemporal distributions of the influence of these factors on northern high-latitude wetland CH4 emissions using an enhanced version of the Variable Infiltration Capacity (VIC) land surface model. We simulated CH4 emissions from wetlands across the pan-Arctic domain over the period 1948-2006, yielding annual average emissions of 36.1 ± 6.7 Tg CH4 yr-1 for the period 1997-2006. We characterized historical sensitivities of CH4 emissions to air temperature, precipitation, incident long- and shortwave radiation, and atmospheric [CO2] as a function of average summer air temperature and precipitation. Emissions from relatively warm and dry wetlands in the southern (permafrost-free) portion of the domain were positively correlated with precipitation and negatively correlated with air temperature, while emissions from wetter and colder wetlands further north (permafrost) were positively correlated with air temperature. Over the entire period 1948-2006, our reconstructed CH4 emissions increased by 20 %, the majority of which can be attributed to an increasing trend in summer air temperature. We estimated future emissions in response to 21st century warming as predicted by CMIP5 (Coupled Model Intercomparison Project Phase 5) model projections to result in end-of-century CH4 emissions 38-53 % higher than our reconstructed 1997-2006 emissions, accompanied by the northward migration of warmer and drier than optimal conditions for CH4 emissions, implying a reduced role for temperature in driving future increases in emissions.

  16. American mastodon extirpation in the Arctic and Subarctic predates human colonization and terminal Pleistocene climate change.

    PubMed

    Zazula, Grant D; MacPhee, Ross D E; Metcalfe, Jessica Z; Reyes, Alberto V; Brock, Fiona; Druckenmiller, Patrick S; Groves, Pamela; Harington, C Richard; Hodgins, Gregory W L; Kunz, Michael L; Longstaffe, Fred J; Mann, Daniel H; McDonald, H Gregory; Nalawade-Chavan, Shweta; Southon, John R

    2014-12-30

    Existing radiocarbon ((14)C) dates on American mastodon (Mammut americanum) fossils from eastern Beringia (Alaska and Yukon) have been interpreted as evidence they inhabited the Arctic and Subarctic during Pleistocene full-glacial times (∼ 18,000 (14)C years B.P.). However, this chronology is inconsistent with inferred habitat preferences of mastodons and correlative paleoecological evidence. To establish a last appearance date (LAD) for M. americanum regionally, we obtained 53 new (14)C dates on 36 fossils, including specimens with previously published dates. Using collagen ultrafiltration and single amino acid (hydroxyproline) methods, these specimens consistently date to beyond or near the ∼ 50,000 y B.P. limit of (14)C dating. Some erroneously "young" (14)C dates are due to contamination by exogenous carbon from natural sources and conservation treatments used in museums. We suggest mastodons inhabited the high latitudes only during warm intervals, particularly the Last Interglacial [Marine Isotope Stage (MIS) 5] when boreal forests existed regionally. Our (14)C dataset suggests that mastodons were extirpated from eastern Beringia during the MIS 4 glacial interval (∼ 75,000 y ago), following the ecological shift from boreal forest to steppe tundra. Mastodons thereafter became restricted to areas south of the continental ice sheets, where they suffered complete extinction ∼ 10,000 (14)C years B.P. Mastodons were already absent from eastern Beringia several tens of millennia before the first humans crossed the Bering Isthmus or the onset of climate changes during the terminal Pleistocene. Local extirpations of mastodons and other megafaunal populations in eastern Beringia were asynchrononous and independent of their final extinction south of the continental ice sheets. PMID:25453065

  17. American mastodon extirpation in the Arctic and Subarctic predates human colonization and terminal Pleistocene climate change

    PubMed Central

    Zazula, Grant D.; MacPhee, Ross D. E.; Metcalfe, Jessica Z.; Reyes, Alberto V.; Brock, Fiona; Druckenmiller, Patrick S.; Groves, Pamela; Harington, C. Richard; Hodgins, Gregory W. L.; Kunz, Michael L.; Longstaffe, Fred J.; Mann, Daniel H.; McDonald, H. Gregory; Nalawade-Chavan, Shweta; Southon, John R.

    2014-01-01

    Existing radiocarbon (14C) dates on American mastodon (Mammut americanum) fossils from eastern Beringia (Alaska and Yukon) have been interpreted as evidence they inhabited the Arctic and Subarctic during Pleistocene full-glacial times (∼18,000 14C years B.P.). However, this chronology is inconsistent with inferred habitat preferences of mastodons and correlative paleoecological evidence. To establish a last appearance date (LAD) for M. americanum regionally, we obtained 53 new 14C dates on 36 fossils, including specimens with previously published dates. Using collagen ultrafiltration and single amino acid (hydroxyproline) methods, these specimens consistently date to beyond or near the ∼50,000 y B.P. limit of 14C dating. Some erroneously “young” 14C dates are due to contamination by exogenous carbon from natural sources and conservation treatments used in museums. We suggest mastodons inhabited the high latitudes only during warm intervals, particularly the Last Interglacial [Marine Isotope Stage (MIS) 5] when boreal forests existed regionally. Our 14C dataset suggests that mastodons were extirpated from eastern Beringia during the MIS 4 glacial interval (∼75,000 y ago), following the ecological shift from boreal forest to steppe tundra. Mastodons thereafter became restricted to areas south of the continental ice sheets, where they suffered complete extinction ∼10,000 14C years B.P. Mastodons were already absent from eastern Beringia several tens of millennia before the first humans crossed the Bering Isthmus or the onset of climate changes during the terminal Pleistocene. Local extirpations of mastodons and other megafaunal populations in eastern Beringia were asynchrononous and independent of their final extinction south of the continental ice sheets. PMID:25453065

  18. How will climate change affect vine behaviour in different soils?

    NASA Astrophysics Data System (ADS)

    Leibar, Urtzi; Aizpurua, Ana; Morales, Fermin; Pascual, Inmaculada; Unamunzaga, Olatz

    2014-05-01

    and water-deficit had a clear influence on the grape phenological development and composition, whilst soil affected root configuration and anthocyanins concentration. Effects of climate change and water availability on different soil conditions should be considered to take full advantage or mitigate the consequences of the future climate conditions.

  19. Affects of Changes in Sea Ice Cover on Bowhead Whales and Subsistence Whaling in the Western Arctic

    NASA Astrophysics Data System (ADS)

    Moore, S.; Suydam, R.; Overland, J.; Laidre, K.; George, J.; Demaster, D.

    2004-12-01

    Global warming may disproportionately affect Arctic marine mammals and disrupt traditional subsistence hunting activities. Based upon analyses of a 24-year time series (1979-2002) of satellite-derived sea ice cover, we identified significant positive trends in the amount of open-water in three large and five small-scale regions in the western Arctic, including habitats where bowhead whales (Balaena mysticetus) feed or are suspected to feed. Bowheads are the only mysticete whale endemic to the Arctic and a cultural keystone species for Native peoples from northwestern Alaska and Chukotka, Russia. While copepods (Calanus spp.) are a mainstay of the bowhead diet, prey sampling conducted in the offshore region of northern Chukotka and stomach contents from whales harvested offshore of the northern Alaskan coast indicate that euphausiids (Thysanoessa spp.) advected from the Bering Sea are also common prey in autumn. Early departure of sea ice has been posited to control availability of zooplankton in the southeastern Bering Sea and in the Cape Bathurst polynya in the southeastern Canadian Beaufort Sea, with maximum secondary production associated with a late phytoplankton bloom in insolatoin-stratified open water. While it is unclear if declining sea-ice has directly affected production or advection of bowhead prey, an extension of the open-water season increases opportunities for Native subsistence whaling in autumn. Therefore, bowhead whales may provide a nexus for simultaneous exploration of the effects sea ice reduction on pagophillic marine mammals and on the social systems of the subsistence hunting community in the western Arctic. The NOAA/Alaska Fisheries Science Center and NSB/Department of Wildlife Management will investigate bowhead whale stock identity, seasonal distribution and subsistence use patterns during the International Polar Year, as an extension of research planned for 2005-06. This research is in response to recommendations from the Scientific

  20. Temporal constraints on future accumulation-area loss of a major Arctic ice cap due to climate change (Vestfonna, Svalbard).

    PubMed

    Möller, Marco; Schneider, Christoph

    2015-01-01

    Arctic glaciers and ice caps are major contributors to past, present and future sea-level fluctuations. Continued global warming may eventually lead to the equilibrium line altitudes of these ice masses rising above their highest points, triggering unstoppable downwasting. This may feed future sea-level rise considerably. We here present projections for the timing of equilibrium-line loss at the major Arctic ice cap Vestfonna, Svalbard. The projections are based on spatially distributed climatic mass balance modelling driven by the outputs of multiple climate models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) forced by the Representative Concentration Pathways (RCPs) 2.6, 4.5, 6.0 and 8.5. Results indicate strongly decreasing climatic mass balances over the 21(st) century for all RCPs considered. Glacier-wide mass-balance rates will drop down to -4 m a(-1) w.e. (water equivalent) at a maximum. The date at which the equilibrium line rises above the summit of Vestfonna (630 m above sea level) is calculated to range between 2040 and 2150, depending on scenario. PMID:25628045

  1. Temporal constraints on future accumulation-area loss of a major Arctic ice cap due to climate change (Vestfonna, Svalbard)

    NASA Astrophysics Data System (ADS)

    Möller, Marco; Schneider, Christoph

    2015-01-01

    Arctic glaciers and ice caps are major contributors to past, present and future sea-level fluctuations. Continued global warming may eventually lead to the equilibrium line altitudes of these ice masses rising above their highest points, triggering unstoppable downwasting. This may feed future sea-level rise considerably. We here present projections for the timing of equilibrium-line loss at the major Arctic ice cap Vestfonna, Svalbard. The projections are based on spatially distributed climatic mass balance modelling driven by the outputs of multiple climate models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) forced by the Representative Concentration Pathways (RCPs) 2.6, 4.5, 6.0 and 8.5. Results indicate strongly decreasing climatic mass balances over the 21st century for all RCPs considered. Glacier-wide mass-balance rates will drop down to -4 m a-1 w.e. (water equivalent) at a maximum. The date at which the equilibrium line rises above the summit of Vestfonna (630 m above sea level) is calculated to range between 2040 and 2150, depending on scenario.

  2. Temporal constraints on future accumulation-area loss of a major Arctic ice cap due to climate change (Vestfonna, Svalbard)

    PubMed Central

    Möller, Marco; Schneider, Christoph

    2015-01-01

    Arctic glaciers and ice caps are major contributors to past, present and future sea-level fluctuations. Continued global warming may eventually lead to the equilibrium line altitudes of these ice masses rising above their highest points, triggering unstoppable downwasting. This may feed future sea-level rise considerably. We here present projections for the timing of equilibrium-line loss at the major Arctic ice cap Vestfonna, Svalbard. The projections are based on spatially distributed climatic mass balance modelling driven by the outputs of multiple climate models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) forced by the Representative Concentration Pathways (RCPs) 2.6, 4.5, 6.0 and 8.5. Results indicate strongly decreasing climatic mass balances over the 21st century for all RCPs considered. Glacier-wide mass-balance rates will drop down to −4 m a−1 w.e. (water equivalent) at a maximum. The date at which the equilibrium line rises above the summit of Vestfonna (630 m above sea level) is calculated to range between 2040 and 2150, depending on scenario. PMID:25628045

  3. Cumulative effects of climate warming and other human activities on freshwaters of Arctic and subarctic North America.

    PubMed

    Schindler, David W; Smol, John P

    2006-06-01

    Despite their generally isolated geographic locations, the freshwaters of the north are subjected to a wide spectrum of environmental stressors. High-latitude regions are especially sensitive to the effects of recent climatic warming, which have already resulted in marked regime shifts in the biological communities of many Arctic lakes and ponds. Important drivers of these limnological changes have included changes in the amount and duration of snow and ice cover, and, for rivers and lakes in their deltas, the frequency and extent of spring floods. Other important climate-related shifts include alterations in evaporation and precipitation ratios, marked changes in the quality and quantity of lake and river water inflows due to accelerated glacier and permafrost melting, and declining percentages of precipitation that falls as snow. The depletion of stratospheric ozone over the north, together with the clarity of many Arctic lakes, renders them especially susceptible to damage from ultraviolet radiation. In addition, the long-range atmospheric transport of pollutants, coupled with the focusing effects of contaminant transport from biological vectors to some local ecosystems (e.g., salmon nursery lakes, ponds draining seabird colonies) and biomagnification in long food chains, have led to elevated concentrations of many persistent organic pollutants (e.g., insecticides, which have never been used in Arctic regions) and other pollutants (e.g., mercury). Rapid development of gas and oil pipelines, mining for diamonds and metals, increases in human populations, and the development of all-season roads, seaports, and hydroelectric dams will stress northern aquatic ecosystems. The cumulative effects of these stresses will be far more serious than those caused by changing climate alone. PMID:16944640

  4. The Role of Disturbance in Arctic Ecosystem Response to a Changing Climate

    NASA Astrophysics Data System (ADS)

    Hinzman, L. D.

    2014-12-01

    Wildfires in the tundra regions and the boreal forest project an immediate effect upon the surface energy and water budget by drastically altering the surface albedo, roughness, infiltration rates, and moisture absorption capacity in organic soils. Although fires create a sudden and drastic change to the landcover, it is only the beginning of a long process of recovery and perhaps a shift to a different successional pathway. In permafrost regions, these effects become part of a process of long-term (20-50 years) cumulative impacts. Burn severity may largely determine immediate impacts and long-term disturbance trajectories. As transpiration decreases or ceases, soil moisture increases markedly, remaining quite wet throughout the year. Because the insulating quality of the organic layer is removed during fires, permafrost begins to thaw near the surface and warm to greater depths. Within a few years, it may thaw to the point where it can no longer completely refreeze every winter, creating a permanently thawed layer in the soil called a talik. After formation of a talik, soils can drain internally throughout the year. At this point, soils may become quite dry, as the total precipitation received annually in the Arctic is quite low. The local ecological community must continuously adapt to the changing soil thermal and moisture regimes. The wet soils found over shallow permafrost favor black spruce forests. After a fire creates a deeper permafrost table (thicker active layer) the invading tree species tend to be birch or alder. The hydrologic and thermal regime of the soil is the primary factor controlling these vegetation trajectories and the subsequent changes in surface mass and energy fluxes. The complexities of a changing climate accentuate these processes of change and complicate predictions of the resulting vegetation trajectories. Understanding these shifts in vegetative communities and quantifying the consequences of thawing permafrost can only be

  5. Are Increasing Freshwater Inputs To The Arctic Ocean Linked To Climate Change?

    NASA Astrophysics Data System (ADS)

    Peterson, B. J.; Holmes, R. M.; McClelland, J. W.; Curry, R. G.

    2004-12-01

    The global hydrological cycle has shown evidence of acceleration over the past 40 years. Evidence includes increasing evaporation from low latitude oceans and increasing precipitation, especially at high latitudes. Net melting of arctic glaciers plus runoff from Eurasian arctic rivers alone have added about 4000 km3 of extra (anomaly from baseline conditions) freshwater to the Arctic Ocean since about 1960. Glacier melt is primarily driven by arctic warming. The Eurasian discharge monitoring includes 2/3 of total Eurasian runoff which comprises 60% of pan-arctic runoff. An investigation of mechanisms driving changes in Eurasian runoff showed that dams, fires and permafrost melt were probably not the major factors causing increased discharge. The discharge changes appear to be driven by the acceleration of the hemispheric hydrologic cycle driven by warming and possibly by shifts in wind directions. Over the same 40 years the high latitude oceans have freshened. A coordinated effort to reconcile the changes in freshwater inputs with changes in freshwater inventory of the Arctic Ocean, Nordic Seas and North Atlantic over the past 40-50 years would be a valuable contribution.

  6. Record Arctic ozone depletion could occur again

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2012-02-01

    In the winter of 2010-2011, ozone levels above the Arctic declined to record lows, creating the first Arctic ozone hole, similar to the well-known Antarctic ozone hole. Scientists believe the ozone depletion was due partly to unusually cold temperatures in the stratosphere above the Arctic, as colder stratospheric temperatures make ozone-destroying chemicals such as chlorine more active. As global climate change continues, the Arctic stratosphere is expected to get colder, but levels of ozone-destroying chemicals should decline, as emissions of these chemicals were banned by the Montreal Protocol. To try to learn more about Arctic ozone dynamics and determine whether the Arctic ozone hole is likely to recur, Sinnhuber et al. looked at satellite observations of temperature, ozone, water vapor, and chemicals that affect ozone in the Arctic atmosphere. They also used a model to determine how sensitive ozone levels are to stratospheric temperatures and chemistry. They found that their model accurately reproduced measured conditions. Their model suggests that stratospheric temperatures 1°C lower than in the 2010-2011 winter would result in locally nearly complete ozone depletion in the Arctic lower stratosphere with current levels of chemicals. A 10% reduction in ozone-depleting chemicals would be offset by a 1°C decrease in stratospheric temperatures.

  7. Communicating climate science to high school students in the Arctic: Adventure Learning @ Greenland

    NASA Astrophysics Data System (ADS)

    Hougham, R. J.; Miller, B.; Cox, C. J.

    2012-12-01

    Adventure Learning @ Greenland (AL@GL) engaged high school students in atmospheric research in the Arctic and in local environments to enhance climate literacy. The overarching objective for this project was to support climate literacy in high school students, specifically the concept of energy exchange between the Earth, atmosphere, and space. The goal then is to produce a model of education and outreach for remote STEM research that can be used to meaningfully engage K-12 and public communities. Over the course of the program experience, students conducted scientific inquiry associated with their place that supported a more focused science content at a field location. Approximately 45 students participated in the hybrid learning environments as part of this project at multiple locations in Idaho, USA, and Greenland. In Greenland, the Summit Camp research station located on the Greenland Ice Sheet was the primary location. The AL@GL project provided a compelling opportunity to engage students in an inquiry-based curriculum alongside a cutting-edge geophysical experiment at Summit: the Integrated Characterization of Energy, Clouds, Atmospheric state, and Precipitation at Summit (ICECAPS) experiment. ICECAPS measures parameters that are closely tied to those identified in student misconceptions. Thus, ICECAPS science and the AL@ approach combined to create a learning environment that was practical, rich, and engaging. Students participating in this project were diverse, rural, and traditionally underrepresented. Groups included: students participating in a field school at Kangerlussuaq, Greenland and Summit Station as members of the JSEP; students at MOSS will were part of the Upward Bound Math Science (UBMS) and HOIST (Helping Orient Indian Students and Teachers) project. These project serve high school students who are first college generation and from low-income families. JSEP is an international group of students from the United States, Greenland, and Denmark

  8. The evolution of climatically driven weathering inputs into the western Arctic Ocean since the late Miocene: Radiogenic isotope evidence

    NASA Astrophysics Data System (ADS)

    Dausmann, Veit; Frank, Martin; Siebert, Christopher; Christl, Marcus; Hein, James R.

    2015-06-01

    We present the first continuous records of dissolved radiogenic neodymium, hafnium, and lead isotope compositions of deep waters in the western Arctic Ocean, spanning the time from the late Miocene to the present. The data were obtained from three hydrogenetic ferromanganese (Fe-Mn) crusts recovered from seamounts along the northernmost edge of the Northwind Ridge in the Canada Basin from water depths of 2200, 2400, and 3600 m. Dating the crusts using cosmogenic 10Be documents undisturbed present-day growth surfaces and yields growth rates between 27 and 2.2 mm/Myr. The Nd (Hf) isotope time series of the three crusts show similar evolutions from εNd (εHf) of -8.5 (+4) in the oldest parts to -11.5 (-4) at the surfaces and a pronounced trend to less radiogenic values starting at ∼4 Ma. This coincided with a trend of the Pb isotope evolution towards more radiogenic 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb. It is inferred that climatically controlled changes in weathering regime and sediment transport along the North American continent were responsible for the major change of the radiogenic isotope composition of the Arctic Deep Water (ADW) in the Canada Basin. Based on these records we conclude that weathering inputs from the North American continent linked to enhanced glacial conditions started to increase and to influence the radiogenic isotope composition of ADW ∼4 million years ago and were further intensified at ∼1 Ma. These new time series differ markedly from the radiogenic isotope evolution of Arctic Intermediate Water recorded on the Lomonosov Ridge and suggest that much larger isotopic differences between the water masses of the Arctic Ocean than today prevailed in the past.

  9. Global water resources affected by human interventions and climate change.

    PubMed

    Haddeland, Ingjerd; Heinke, Jens; Biemans, Hester; Eisner, Stephanie; Flörke, Martina; Hanasaki, Naota; Konzmann, Markus; Ludwig, Fulco; Masaki, Yoshimitsu; Schewe, Jacob; Stacke, Tobias; Tessler, Zachary D; Wada, Yoshihide; Wisser, Dominik

    2014-03-01

    Humans directly change the dynamics of the water cycle through dams constructed for water storage, and through water withdrawals for industrial, agricultural, or domestic purposes. Climate change is expected to additionally affect water supply and demand. Here, analyses of climate change and direct human impacts on the terrestrial water cycle are presented and compared using a multimodel approach. Seven global hydrological models have been forced with multiple climate projections, and with and without taking into account impacts of human interventions such as dams and water withdrawals on the hydrological cycle. Model results are analyzed for different levels of global warming, allowing for analyses in line with temperature targets for climate change mitigation. The results indicate that direct human impacts on the water cycle in some regions, e.g., parts of Asia and in the western United States, are of the same order of magnitude, or even exceed impacts to be expected for moderate levels of global warming (+2 K). Despite some spread in model projections, irrigation water consumption is generally projected to increase with higher global mean temperatures. Irrigation water scarcity is particularly large in parts of southern and eastern Asia, and is expected to become even larger in the future. PMID:24344275

  10. Terrestrial carbon cycle affected by non-uniform climate warming

    NASA Astrophysics Data System (ADS)

    Xia, Jianyang; Chen, Jiquan; Piao, Shilong; Ciais, Philippe; Luo, Yiqi; Wan, Shiqiang

    2014-03-01

    Feedbacks between the terrestrial carbon cycle and climate change could affect many ecosystem functions and services, such as food production, carbon sequestration and climate regulation. The rate of climate warming varies on diurnal and seasonal timescales. A synthesis of global air temperature data reveals a greater rate of warming in winter than in summer in northern mid and high latitudes, and the inverse pattern in some tropical regions. The data also reveal a decline in the diurnal temperature range over 51% of the global land area and an increase over only 13%, because night-time temperatures in most locations have risen faster than daytime temperatures. Analyses of satellite data, model simulations and in situ observations suggest that the impact of seasonal warming varies between regions. For example, spring warming has largely stimulated ecosystem productivity at latitudes between 30° and 90° N, but suppressed productivity in other regions. Contrasting impacts of day- and night-time warming on plant carbon gain and loss are apparent in many regions. We argue that ascertaining the effects of non-uniform climate warming on terrestrial ecosystems is a key challenge in carbon cycle research.

  11. Global water resources affected by human interventions and climate change

    PubMed Central

    Haddeland, Ingjerd; Heinke, Jens; Biemans, Hester; Eisner, Stephanie; Flörke, Martina; Hanasaki, Naota; Konzmann, Markus; Ludwig, Fulco; Masaki, Yoshimitsu; Schewe, Jacob; Stacke, Tobias; Tessler, Zachary D.; Wada, Yoshihide; Wisser, Dominik

    2014-01-01

    Humans directly change the dynamics of the water cycle through dams constructed for water storage, and through water withdrawals for industrial, agricultural, or domestic purposes. Climate change is expected to additionally affect water supply and demand. Here, analyses of climate change and direct human impacts on the terrestrial water cycle are presented and compared using a multimodel approach. Seven global hydrological models have been forced with multiple climate projections, and with and without taking into account impacts of human interventions such as dams and water withdrawals on the hydrological cycle. Model results are analyzed for different levels of global warming, allowing for analyses in line with temperature targets for climate change mitigation. The results indicate that direct human impacts on the water cycle in some regions, e.g., parts of Asia and in the western United States, are of the same order of magnitude, or even exceed impacts to be expected for moderate levels of global warming (+2 K). Despite some spread in model projections, irrigation water consumption is generally projected to increase with higher global mean temperatures. Irrigation water scarcity is particularly large in parts of southern and eastern Asia, and is expected to become even larger in the future. PMID:24344275

  12. Landfast ice affects the stability of the Arctic halocline: Evidence from a numerical model

    NASA Astrophysics Data System (ADS)

    Itkin, Polona; Losch, Martin; Gerdes, Rüdiger

    2015-04-01

    Landfast ice covers large surface areas of the winter Siberian Seas. The immobile landfast ice cover inhibits divergent and convergent motion, hence dynamical sea ice growth and redistribution, decouples winter river plumes in coastal seas from the atmosphere, and positions polynyas at the landfast ice edge offshore. In spite of the potentially large effects, state-of-the-art numerical models usually do not represent landfast ice in its correct extent. A simple parametrization of landfast ice based on bathymetry and internal sea ice strength is introduced and its effects on the simulated Arctic Ocean are demonstrated. The simulations suggest that the Siberian landfast ice impacts the Arctic halocline stability through enhanced brine production in polynyas located closer to the shelf break and by redirecting river water to the Canadian Basin. These processes strengthen the halocline in the Canadian Basin, but erode its stability in the Makarov and Eurasian Basins.

  13. The Arctic in the Anthropocene: a Report from the National Academy of Sciences

    NASA Astrophysics Data System (ADS)

    Everett, L. M.; Huntington, H. P.; Pfirman, S. L.

    2014-12-01

    With rapid change unfolding throughout the Arctic, the need for actionable Arctic science has never been greater. A warming climate is reshaping Arctic ecosystems, bringing changes such as the loss of sea ice and glaciers, thawing of permafrost, and changing snow patterns. These shifts challenge Arctic citizens who must adapt to new environmental conditions, and have significant global implications. A 2014 National Research Council report, The Arctic in the Anthropocene: Emerging Research Questions, identifies research questions important for understanding how environmental and societal transitions will affect the Arctic and the rest of the world. It also assesses what is required to address these questions, and points to the need to translate research findings into practical information that can help guide management and policy decisions. Drawing upon the report, this presentation will focus on the scientific research questions identified under five categories: Evolving Arctic, Hidden Arctic, Connected Arctic, Managed Arctic, and Undetermined Arctic. It will also address methods to meet the challenges and assess what is needed to leverage efficiencies in making Arctic research happen, from collaboration and coordination to sustained observations, building human and operational capacity, making information actionable as well as accessible, and possible changes in funding approaches. It will demonstrate that fostering a sense of shared purpose to manage change to the best of our abilities is essential, as is a continued commitment to studying what exists, what is emerging, and what awaits us in the Arctic.

  14. Comparative Phylogeography Highlights the Double-Edged Sword of Climate Change Faced by Arctic- and Alpine-Adapted Mammals

    PubMed Central

    Lanier, Hayley C.; Gunderson, Aren M.; Weksler, Marcelo; Fedorov, Vadim B.; Olson, Link E.

    2015-01-01

    Recent studies suggest that alpine and arctic organisms may have distinctly different phylogeographic histories from temperate or tropical taxa, with recent range contraction into interglacial refugia as opposed to post-glacial expansion out of refugia. We use a combination of phylogeographic inference, demographic reconstructions, and hierarchical Approximate Bayesian Computation to test for phylodemographic concordance among five species of alpine-adapted small mammals in eastern Beringia. These species (Collared Pikas, Hoary Marmots, Brown Lemmings, Arctic Ground Squirrels, and Singing Voles) vary in specificity to alpine and boreal-tundra habitat but share commonalities (e.g., cold tolerance and nunatak survival) that might result in concordant responses to Pleistocene glaciations. All five species contain a similar phylogeographic disjunction separating eastern and Beringian lineages, which we show to be the result of simultaneous divergence. Genetic diversity is similar within each haplogroup for each species, and there is no support for a post-Pleistocene population expansion in eastern lineages relative to those from Beringia. Bayesian skyline plots for four of the five species do not support Pleistocene population contraction. Brown Lemmings show evidence of late Quaternary demographic expansion without subsequent population decline. The Wrangell-St. Elias region of eastern Alaska appears to be an important zone of recent secondary contact for nearctic alpine mammals. Despite differences in natural history and ecology, similar phylogeographic histories are supported for all species, suggesting that these, and likely other, alpine- and arctic-adapted taxa are already experiencing population and/or range declines that are likely to synergistically accelerate in the face of rapid climate change. Climate change may therefore be acting as a double-edged sword that erodes genetic diversity within populations but promotes divergence and the generation of

  15. Comparative phylogeography highlights the double-edged sword of climate change faced by arctic- and alpine-adapted mammals.

    PubMed

    Lanier, Hayley C; Gunderson, Aren M; Weksler, Marcelo; Fedorov, Vadim B; Olson, Link E

    2015-01-01

    Recent studies suggest that alpine and arctic organisms may have distinctly different phylogeographic histories from temperate or tropical taxa, with recent range contraction into interglacial refugia as opposed to post-glacial expansion out of refugia. We use a combination of phylogeographic inference, demographic reconstructions, and hierarchical Approximate Bayesian Computation to test for phylodemographic concordance among five species of alpine-adapted small mammals in eastern Beringia. These species (Collared Pikas, Hoary Marmots, Brown Lemmings, Arctic Ground Squirrels, and Singing Voles) vary in specificity to alpine and boreal-tundra habitat but share commonalities (e.g., cold tolerance and nunatak survival) that might result in concordant responses to Pleistocene glaciations. All five species contain a similar phylogeographic disjunction separating eastern and Beringian lineages, which we show to be the result of simultaneous divergence. Genetic diversity is similar within each haplogroup for each species, and there is no support for a post-Pleistocene population expansion in eastern lineages relative to those from Beringia. Bayesian skyline plots for four of the five species do not support Pleistocene population contraction. Brown Lemmings show evidence of late Quaternary demographic expansion without subsequent population decline. The Wrangell-St. Elias region of eastern Alaska appears to be an important zone of recent secondary contact for nearctic alpine mammals. Despite differences in natural history and ecology, similar phylogeographic histories are supported for all species, suggesting that these, and likely other, alpine- and arctic-adapted taxa are already experiencing population and/or range declines that are likely to synergistically accelerate in the face of rapid climate change. Climate change may therefore be acting as a double-edged sword that erodes genetic diversity within populations but promotes divergence and the generation of

  16. The role of seasonality and large-scale climate drivers in recent Pan-Arctic tundra vegetation variability and change

    NASA Astrophysics Data System (ADS)

    Bhatt, U. S.; Walker, D. A.; Bieniek, P. A.; Raynolds, M. K.; Comiso, J. C.; Pinzon, J.; Tucker, C. J.

    2011-12-01

    An increase of Pan-Arctic tundra vegetation greenness has been documented using the remotely sensed Normalized Difference Vegetation Index (NDVI) and a coherent variability between NDVI, springtime coastal sea ice and land surface temperatures has been shown. The goal of this paper is to understand the forcing factors of this change and variability better through an analysis of the seasonality of these remotely sensed variables as well as long-term climate data sets. This study uses remotely sensed submonthly 25-km sea ice concentration, surface temperature, and NDVI from 1982 to 2010. The NDVI3g data has been corrected for biases in the spring and fall. Standard climate data (station, reanalysis, and model data) and ground observations are also examined. For overall trends, we find that summer time open water area has increased most in the Beaufort, and Siberian Seas. The seasonality of SWI trends display distinct heterogeneity across the Arctic, with maximum warming in August for most regions (Figure 1). The monthly time integrated NDVI trends display the largest positive values for most of the Arctic in July, with the exception of the E. Bering and Kara regions, which show declines during most months (Figure 2). The largest magnitude increases in Max-NDVI tend to be in subzones that are inland, particularly in the Beaufort and Chukchi regions. NDVI has increased more during spring in Eurasia and more during peak vegetation activity (July) over North America. The analysis suggests that local atmospheric circulation as well as other local factors likely plays an important role in vegetation productivity.

  17. On assessment of the relationship between changes of sea ice extent and climate in the Arctic

    NASA Astrophysics Data System (ADS)

    Alekseev, Genrikh; Glok, Natalia; Smirnov, Alexander

    2016-04-01

    An increase of surface air temperature (SAT) in the marine Arctic (a part of the Arctic covered with sea ice in winter) shows a good relationship with reduction of sea ice extent (SIE) in summer. For instance, a strong correlation (a coefficient equal to -0.93) was found between the summer SAT in the marine Arctic and satellite-derived 1980-2014 September sea ice index (the average of sea ice extent in the Arctic since 1978, in millions of sq. km). Based on this finding anomalies of Arctic September SIE were reconstructed from the beginning of twentieth century using linear regression relationship. This reconstructed SIE shows a substantial decrease in the 1930-40s with a minimum occurring in 1936, which, however, is only a half of the decline in 2012. An impact of the inflow of warm and salty Atlantic water on winter SIE was evaluated as an example for the Barents Sea. This evaluation reveals a coherent spatial pattern of the Atlantic water spreading, presented by surface salinity distribution, and the position of sea-ice edge, and significant correlation between the inflow of the Atlantic water and maximal SIE.

  18. On the effects of constraining atmospheric circulation in a coupled atmosphere-ocean Arctic regional climate model

    NASA Astrophysics Data System (ADS)

    Berg, Peter; Döscher, Ralf; Koenigk, Torben

    2015-08-01

    Impacts of spectral nudging on simulations of Arctic climate in coupled simulations have been investigated in a set of simulations with a regional climate model (RCM). The dominantly circumpolar circulation in the Arctic lead to weak constraints on the lateral boundary conditions (LBCs) for the RCM, which causes large internal variability with strong deviations from the driving model. When coupled to an ocean and sea ice model, this results in sea ice concentrations that deviate from the observed spatial distribution. Here, a method of spectral nudging is applied to the atmospheric model RCA4 in order to assess the potentials for improving results for the sea ice concentrations when coupled to the RCO ocean-sea ice model. The spectral nudging applied to reanalysis driven simulations significantly improves the generated sea ice regarding its temporal evolution, extent and inter-annual trends, compared to simulations with standard LBC nesting. The method is furthermore evaluated with driving data from two CMIP5 GCM simulations for current and future conditions. The GCM biases are similar to the RCA4 biases with ERA-Interim, however, the spectral nudging still improves the surface winds enough to show improvements in the simulated sea ice. For both GCM downscalings, the spectrally nudged version retains a larger sea ice extent in September further into the future. Depending on the sea ice formulation in the GCM, the temporal evolution of the regional sea ice model can deviate strongly.

  19. On the effects of constraining atmospheric circulation in a coupled atmosphere-ocean Arctic regional climate model

    NASA Astrophysics Data System (ADS)

    Berg, Peter; Döscher, Ralf; Koenigk, Torben

    2016-06-01

    Impacts of spectral nudging on simulations of Arctic climate in coupled simulations have been investigated in a set of simulations with a regional climate model (RCM). The dominantly circumpolar circulation in the Arctic lead to weak constraints on the lateral boundary conditions (LBCs) for the RCM, which causes large internal variability with strong deviations from the driving model. When coupled to an ocean and sea ice model, this results in sea ice concentrations that deviate from the observed spatial distribution. Here, a method of spectral nudging is applied to the atmospheric model RCA4 in order to assess the potentials for improving results for the sea ice concentrations when coupled to the RCO ocean-sea ice model. The spectral nudging applied to reanalysis driven simulations significantly improves the generated sea ice regarding its temporal evolution, extent and inter-annual trends, compared to simulations with standard LBC nesting. The method is furthermore evaluated with driving data from two CMIP5 GCM simulations for current and future conditions. The GCM biases are similar to the RCA4 biases with ERA-Interim, however, the spectral nudging still improves the surface winds enough to show improvements in the simulated sea ice. For both GCM downscalings, the spectrally nudged version retains a larger sea ice extent in September further into the future. Depending on the sea ice formulation in the GCM, the temporal evolution of the regional sea ice model can deviate strongly.

  20. Climate Change and Thawing Permafrost in Two Iñupiaq Communities of Alaska's Arctic: Observations, Implications, and Resilience

    NASA Astrophysics Data System (ADS)

    Woodward, A.; Kofinas, G.

    2013-12-01

    For thousands of years the Iñupiat of northern Alaska have relied on ecosystems underlain by permafrost for material and cultural resources. As permafrost thaws across the Arctic, these social-ecological systems are changing rapidly. Community-based research and extensive local knowledge of Iñupiaq villagers offer unique and valuable contributions to understanding permafrost change and its implications for humans. We partnered with two Iñupiaq communities in Alaska's Arctic to investigate current and potential effects of thawing permafrost on social-ecological systems. Anaktuvuk Pass is situated on thaw-stable consolidated gravel in the Brooks Range, while Selawik rests on ice-rich permafrost in Beringia lowland tundra. Using the transdisciplinary approach of resilience theory and mixed geophysical and ethnographic methods, we measured active layer thaw depths and documented local knowledge about climate and permafrost change. Thaw depths were greater overall in Selawik. Residents of both communities reported a variety of changes in surface features, hydrology, weather, flora, and fauna that they attribute to thawing permafrost and / or climate change. Overall, Selawik residents described more numerous and extreme examples of such changes, expressed higher degrees of certainty that change is occurring, and anticipated more significant and negative implications for their way of life than did residents of Anaktuvuk Pass. Of the two villages, Selawik faces greater and more immediate challenges to the resilience of its social-ecological system as permafrost thaws.

  1. Is the Climate of Bering Sea Warming and Affecting the Ecosystem?

    NASA Astrophysics Data System (ADS)

    Overland, James E.; Stabeno, Phyllis J.

    2004-08-01

    Observations from the Bering Sea are good indicators of decadal shifts in climate, as the Bering is a transition region between the cold, dry Arctic air mass to the north, and the moist, relatively warm maritime air mass to the south. The Bering Sea is also a transition region between Arctic and sub-Arctic ecosystems; this boundary can be loosely identified with the extent of winter sea-ice cover. Like a similar transition zone in the eastern North Atlantic, the Bering Sea is experiencing a northward biogeographical shift in response to changing temperature and atmospheric forcing. If this shift continues over the next decade, it will have major impacts on commercial and subsistence harvests as Arctic species are displaced by sub-Arctic species. The stakes are enormous, as this rich and diverse ecosystem currently provides 47% of the U.S. fishery production by weight, and is home to 80% of the U.S. sea bird population, 95% of northern fur seals, and major populations of Steller sea lions, walrus, and whales.

  2. The Arctic CH4 sink and its implications for the permafrost carbon feedbacks to the global climate system

    NASA Astrophysics Data System (ADS)

    Juncher Jørgensen, Christian; Christiansen, Jesper; Mariager, Tue; Hugelius, Gustaf

    2016-04-01

    Using atmospheric methane (CH4), certain soil microbes are able to sustain their metabolism, and in turn remove this powerful greenhouse gas from the atmosphere. While the process of CH4 oxidation is a common feature in most natural and unmanaged ecosystems in temperate and boreal ecosystems, the interactions between soil physical properties and abiotic process drivers, net landscape exchange and spatial patterns across Arctic drylands remains highly uncertain. Recent works show consistent CH4 comsumption in upland dry tundra soils in Arctic and High Arctic environments (Christiansen et al., 2014, Biogeochemistry 122; Jørgensen et al., 2015, Nature Geoscience 8; Lau et al., 2015, The ISME Journal 9). In these dominantly dry or barren soil ecosystems, CH4 consumption has been observed to significantly exceed the amounts of CH4 emitted from adjacent wetlands. These observations point to a potentially important but largely overlooked component of the global soil-climate system interaction and a counterperspective to the conceptual understanding of the Arctic being a only a source of CH4. However, due to our limited knowledge of spatiotemporal occurrence of CH4 consumption across a wider range of the Arctic landscape we are left with substantial uncertainites and an overall unconstrained range estimate of this terrestrial CH4 sink and its potential effects on permafrost carbon feedback to the atmospheric CH4 concentration. To address this important knowledge gap and identify the most relevant spatial scaling parameters, we studied in situ CH4 net exchange across a large landscape transect on West Greenland. The transect representated soils formed from the dominant geological parent materials of dry upland tundra soils found in the ice-free land areas of Western Greenland, i.e. 1) granitic/gneissic parent material, 2) basaltic parent material and 3) sedimentary deposits. Results show that the dynamic variations in soil physical properties and soil hydrology exerts an

  3. Observational Constraints on Changing Arctic Methane Emissions

    NASA Astrophysics Data System (ADS)

    Dlugokencky, E. J.; Bruhwiler, L.; Lang, P. M.; Masarie, K.; Crotwell, A. M.; Crotwell, M.; Lowry, D.; Fisher, R. E.; Nisbet, E. G.

    2012-12-01

    Methane (CH4) is the second-most important greenhouse gas influenced by human activities. Its chemistry results in additional indirect climate effects from production of tropospheric O3, which also affects air quality, and stratospheric H2O. Because methane's atmospheric lifetime is relatively short (~9 yr) and ~70% of its emissions are anthropogenic, reductions in its emissions provide a potential cost-effective opportunity to slow the rate of increase of radiative forcing. Some fraction of decreased anthropogenic emissions may be canceled by potentially strong feed-backs to natural emissions. Because natural emissions of CH4 are diffuse, relatively weak, and highly-variable in space and time, quantifying changes for large spatial regions is difficult from small-scale field studies alone. Atmosphere observations at well-chosen sites integrate these emissions over large zonal regions and can be particularly useful for detecting changes in emissions. Paleo-climate studies indicate that CH4 emissions from Arctic wetlands are sensitive to climate and may provide a strong positive feedback as the Arctic warms. Measurements of atmospheric CH4 from the NOAA Global Monitoring Division's, Global Cooperative Air Sampling Network began in 1983. These high-precision observations offer key constraints on changes in Arctic CH4 emissions. During 2007, the CH4 growth rate increased in the Arctic, but was nearly zero during 2008. Use of the data in a chemical transport model suggest anomalous emissions of about 2 Tg CH4 during 2007, but returning to long-term average emissions after that. Another potential source affected by climate is emissions from methane clathrates. Measurements of methane's isotopic composition in the Arctic have been useful in showing that CH4 enhancements in Arctic air result from wetlands, not clathrates. Both potential sources are also constrained by spatial patterns in observed CH4, which indicate that, so far, changes in emissions of Arctic CH4 over the

  4. The Response to Climate Change of the Cold Arctic Halocline, Shielding Sea Ice from the Warm Deep Water Below

    NASA Astrophysics Data System (ADS)

    Reddy, T. E.; Palmer, M. A.; Arrigo, K. R.; Holland, D. M.

    2011-12-01

    The cold halocline layer of the Arctic Ocean shields the ice cover from an upward flux of heat from the underlying warm Atlantic water. Since this cold layer insulates the surface layer and ice from the heat below, changes in heat content and depth of this layer may have a profound effect on the surface energy and mass balance of sea ice in this region. In contrast to the halocline in the Eastern Arctic basins, the halocline in the Canadian basin is more complex with waters coming from both the Atlantic and Pacific. In this research study, we explored the physical environment of two Arctic shelf regions: the Alaskan Shelf and the Mackenzie Shelf. Here, we compare results from the Mackenzie Alaskan Shelf System (MASS) model (with which we run coupled ocean-ice-atmosphere simulations) to field data from two sets of cruises to the area: the Canadian Arctic Shelf Exchange Study (CASES) to the Mackenzie Shelf and Beaufort Sea and the Shelf-Basin Interaction (SBI) study to the Alaskan Shelf and Chukchi and Beaufort Seas. We investigate the physical connections of the shelves, slopes, and deep basins using results from our model. Heat content in the Atlantic waters below the halocline is large enough to begin melting ice from below if this barrier is weakened or perturbed. One key goal of this study is exploring how this barrier reacts to potential future changes, including the singular and combined affects of increased air temperature and increased wind speed, as well as decreased ice cover. While the perturbations had little effect on the Alaskan Shelf, results of note on the Mackenzie Shelf include a thickening of the halocline in the spring in the increased wind run and a diminishment of the halocline in the fall in both runs in which temperature increased (increased temperature only and increased winds and temperature together). The surface waters were notably warmer in both of these increased temperature runs, with tremendous implications for sea ice cover.

  5. On the impact of arctic wetlands on the climate system: Model sensitivity simulations with MIROC5 AGCM and the simplified wetland scheme

    NASA Astrophysics Data System (ADS)

    Nitta, T.; Yoshimura, K.; Abe-Ouchi, A.

    2015-12-01

    There are many wetlands and lakes in the Arctic. They influence the surface water and energy budget, surface hydrology, and hence climate. In the present study, we examine a simplified wetland scheme that stores part of snowmelt with MATSIRO land surface model in a climate model, MIROC5. We conduct AGCM experiments using MIROC5 with climatological monthly SST and sea ice boundary conditions from 1979 to 1996 with and without the simplified wetland scheme. First, we compare simulated climatology of soil moisture in JJA with satellite based observation data. The result shows that eastern Eurasia has wet bias, and western Eurasia and North America except Alaska have dry bias; this might be caused by precipitation biases. The simulated soil moisture with the wetland scheme increases in high latitudes, about 0.2 for the most affected regions. Then, we evaluate simulated precipitation and surface air temperature using JRA55 reanalysis dataset. In the experiment without the wetland scheme, warm bias exists in most of the land area. By introducing the wetland scheme, the warm bias decreases because the latent heat flux increases and the sensible heat flux decreases. Simulated precipitation without the wetland scheme shows similar bias in soil moisture. It decreases in western Eurasia with the wetland scheme. Further, we evaluate the land-atmosphere coupling strength using rank correlation coefficient of soil moisture and lifting condensation level. The result shows that the effects of wetlands reduce the coupling strength.

  6. Spatial trends and factors affecting variation of organochlorine contaminants levels in Canadian Arctic beluga (Delphinapterus leucas).

    PubMed

    Stern, G A; Macdonald, C R; Armstrong, D; Dunn, B; Fuchs, C; Harwood, L; Muir, D C G; Rosenberg, B

    2005-12-01

    Organochlorine pesticides and PCBs were analysed in blubber from beluga (Delphinapterus leucas), or white whales, collected at 15 sites in the Canadian Arctic between 1993 and 2001. The objective of the study was to define and interpret the spatial trends of major organic contaminants in northern beluga in terms of sources and transport pathways, and the biological factors influencing accumulation. When compared on a lipid weight basis, the concentrations of beta-HCH, cis-CHL and SigmaCHL, cis-nonachlor, heptachlor epoxide and p,p'-DDT were significantly higher in males than females at all five sites in the eastern Arctic where the two sexes were harvested. The differences were attributed to losses from the females during fetal development and lactation as reported in previous studies. Major compounds increased with age in males at most sites, however the lack of a significant increase with age at some sites was in part due to high organochlorine concentrations in young year classes (2-5 years), particularly at eastern sites such as Iqaluit and Pangnirtung. Lower concentrations of SigmaHCH and SigmaDDT compounds in young males in 2001 relative to 1995 at Hendrickson Island could be due to declining levels in the environment, changes in the diet, or differences in organochlorine loads transferred from the female after birth. Age-corrected least square mean concentrations in males showed significantly higher levels of many compounds, such as p,p'-DDE and SigmaCHB, at south Baffin Island sites than those in the west. Two notable exceptions were HCBz and beta-HCH which were higher in the west. Methoxyclor was detected in males at Sanikiluaq (58 ng g-1) and in both sexes at Kimmirut, but at no other sites. Principal component analysis grouped the 16 sites into five major groupings based on the similarity of normalised organochlorine pesticide and PCB levels. Sites from the western Arctic were grouped by higher proportions of HCBz, beta-HCH and gamma-HCH and higher

  7. Near-Surface Meteorology During the Arctic Summer Cloud Ocean Study (ASCOS): Evaluation of Reanalyses and Global Climate Models.

    NASA Technical Reports Server (NTRS)

    De Boer, G.; Shupe, M.D.; Caldwell, P.M.; Bauer, Susanne E.; Persson, O.; Boyle, J.S.; Kelley, M.; Klein, S.A.; Tjernstrom, M.

    2014-01-01

    Atmospheric measurements from the Arctic Summer Cloud Ocean Study (ASCOS) are used to evaluate the performance of three atmospheric reanalyses (European Centre for Medium Range Weather Forecasting (ECMWF)- Interim reanalysis, National Center for Environmental Prediction (NCEP)-National Center for Atmospheric Research (NCAR) reanalysis, and NCEP-DOE (Department of Energy) reanalysis) and two global climate models (CAM5 (Community Atmosphere Model 5) and NASA GISS (Goddard Institute for Space Studies) ModelE2) in simulation of the high Arctic environment. Quantities analyzed include near surface meteorological variables such as temperature, pressure, humidity and winds, surface-based estimates of cloud and precipitation properties, the surface energy budget, and lower atmospheric temperature structure. In general, the models perform well in simulating large-scale dynamical quantities such as pressure and winds. Near-surface temperature and lower atmospheric stability, along with surface energy budget terms, are not as well represented due largely to errors in simulation of cloud occurrence, phase and altitude. Additionally, a development version of CAM5, which features improved handling of cloud macro physics, has demonstrated to improve simulation of cloud properties and liquid water amount. The ASCOS period additionally provides an excellent example of the benefits gained by evaluating individual budget terms, rather than simply evaluating the net end product, with large compensating errors between individual surface energy budget terms that result in the best net energy budget.

  8. Near-surface meteorology during the Arctic Summer Cloud Ocean Study (ASCOS): evaluation of reanalyses and global climate models

    NASA Astrophysics Data System (ADS)

    de Boer, G.; Shupe, M. D.; Caldwell, P. M.; Bauer, S. E.; Persson, O.; Boyle, J. S.; Kelley, M.; Klein, S. A.; Tjernström, M.

    2014-01-01

    Atmospheric measurements from the Arctic Summer Cloud Ocean Study (ASCOS) are used to evaluate the performance of three atmospheric reanalyses (European Centre for Medium Range Weather Forecasting (ECMWF)-Interim reanalysis, National Center for Environmental Prediction (NCEP)-National Center for Atmospheric Research (NCAR) reanalysis, and NCEP-DOE (Department of Energy) reanalysis) and two global climate models (CAM5 (Community Atmosphere Model 5) and NASA GISS (Goddard Institute for Space Studies) ModelE2) in simulation of the high Arctic environment. Quantities analyzed include near surface meteorological variables such as temperature, pressure, humidity and winds, surface-based estimates of cloud and precipitation properties, the surface energy budget, and lower atmospheric temperature structure. In general, the models perform well in simulating large-scale dynamical quantities such as pressure and winds. Near-surface temperature and lower atmospheric stability, along with surface energy budget terms, are not as well represented due largely to errors in simulation of cloud occurrence, phase and altitude. Additionally, a development version of CAM5, which features improved handling of cloud macro physics, has demonstrated to improve simulation of cloud properties and liquid water amount. The ASCOS period additionally provides an excellent example of the benefits gained by evaluating individual budget terms, rather than simply evaluating the net end product, with large compensating errors between individual surface energy budget terms that result in the best net energy budget.

  9. Improvement in Simulation of Eurasian Winter Climate Variability with a Realistic Arctic Sea Ice Condition in an Atmospheric GCM

    NASA Technical Reports Server (NTRS)

    Lim, Young-Kwon; Ham, Yoo-Geun; Jeong, Jee-Hoon; Kug, Jong-Seong

    2012-01-01

    The present study investigates how much a realistic Arctic sea ice condition can contribute to improve simulation of the winter climate variation over the Eurasia region. Model experiments are set up using different sea ice boundary conditions over the past 24 years (i.e., 1988-2011). One is an atmospheric model inter-comparison (AMIP) type of run forced with observed sea-surface temperature (SST), sea ice, and greenhouse gases (referred to as Exp RSI), and the other is the same as Exp RSI except for the sea ice forcing, which is a repeating climatological annual cycle (referred to as Exp CSI). Results show that Exp RSI produces the observed dominant pattern of Eurasian winter temperatures and their interannual variation better than Exp CSI (correlation difference up to approx. 0.3). Exp RSI captures the observed strong relationship between the sea ice concentration near the Barents and Kara seas and the temperature anomaly across Eurasia, including northeastern Asia, which is not well captured in Exp CSI. Lagged atmospheric responses to sea ice retreat are examined using observations to understand atmospheric processes for the Eurasian cooling response including the Arctic temperature increase, sea-level pressure increase, upper-level jet weakening and cold air outbreak toward the mid-latitude. The reproducibility of these lagged responses by Exp RSI is also evaluated.

  10. Heating up Climate Literacy Education: Understanding Teachers' and Students' Motivational and Affective Response to Climate Change

    NASA Astrophysics Data System (ADS)

    Sinatra, G. M.

    2011-12-01

    Changing students' ideas about controversial scientific issues, such as human-induced climate change, presents unique challenges for educators (Lombardi & Sinatra, 2010; Sinatra & Mason, 2008). First, climate science is complex and requires "systems thinking," or the ability to think and reason abstractly about emergent systems (Goldstone & Sakamoto, 2003). Appreciating the intricacies of complex systems and emergent processes has proven challenging for students (Chi, 2005). In addition to these challenges, there are specific misconceptions that may lead thinking astray on the issue of global climate change, such as the distinction between weather and climate (Lombardi & Sinatra, 2010). As an example, when students are asked about their views on climate change, they often recall individual storm events or very cold periods and use their personal experiences and recollections of short-term temperature fluctuations to assess whether the planet is warming. Beyond the conceptual difficulties, controversial topics offer another layer of challenge. Such topics are often embedded in complex socio-cultural and political contexts, have a high degree of uncertainty, and may be perceived by individuals as in conflict with their personal or religious beliefs (Levinson, 2006, Sinatra, Kardash, Taasoobshirazi, & Lombardi, 2011). Individuals are often committed to their own views on socio-scientific issues and this commitment may serve as a motivation to actively resist new ideas (Dole & Sinatra, 1998). Individuals may also have strong emotions associated with their misconceptions (Broughton, Pekrun, & Sinatra, 2011). Negative emotions, misconceptions, and resistance do not make a productive combination for learning. Further, teachers who find human-induced climate change implausible have been shown to hold negative emotions about having to teach about climate change (Lombardi & Sinatra, in preparation), which could affect how they present the topic to students. In this

  11. How does spatial variability of climate affect catchment streamflow predictions?

    NASA Astrophysics Data System (ADS)

    Patil, Sopan D.; Wigington, Parker J.; Leibowitz, Scott G.; Sproles, Eric A.; Comeleo, Randy L.

    2014-09-01

    Spatial variability of climate can negatively affect catchment streamflow predictions if it is not explicitly accounted for in hydrologic models. In this paper, we examine the changes in streamflow predictability when a hydrologic model is run with spatially variable (distributed) meteorological inputs instead of spatially uniform (lumped) meteorological inputs. Both lumped and distributed versions of the EXP-HYDRO model are implemented at 41 meso-scale (500-5000 km2) catchments in the Pacific Northwest region of USA. We use two complementary metrics of long-term spatial climate variability, moisture homogeneity index (IM) and temperature variability index (ITV), to analyze the performance improvement with distributed model. Results show that the distributed model performs better than the lumped model in 38 out of 41 catchments, and noticeably better (>10% improvement) in 13 catchments. Furthermore, spatial variability of moisture distribution alone is insufficient to explain the observed patterns of model performance improvement. For catchments with low moisture homogeneity (IM < 80%), IM is a better predictor of model performance improvement than ITV; whereas for catchments with high moisture homogeneity (IM > 80%), ITV is a better predictor of performance improvement than IM. Based on the results, we conclude that: (1) catchments that have low homogeneity of moisture distribution are the obvious candidates for using spatially distributed meteorological inputs, and (2) catchments with a homogeneous moisture distribution benefit from spatially distributed meteorological inputs if they also have high spatial variability of precipitation phase (rain vs. snow).

  12. Attribution of the Recent Winter Arctic warming and Sea-Ice Decline with Observation-based Data and Coupled Climate Model Simulations

    NASA Astrophysics Data System (ADS)

    Lee, S.; Park, D. S. R.; Feldstein, S. B.; Franzke, C. L. E.

    2015-12-01

    Wintertime Arctic sea ice extent has been declining since the late 20th century, particularly over the Atlantic sector that encompasses the Barents-Kara Seas and Baffin Bay. This sea-ice decline is attributable to various Arctic environmental changes, such as enhanced downward infrared radiation (IR), preseason sea-ice reduction, enhanced inflow of warm Atlantic water into the Arctic Ocean, and sea-ice export. However, their relative contributions are uncertain. Utilizing ERA-Interim reanalysis and satellite-based data, it is shown here that a positive trend of downward IR accounts for nearly half of the sea-ice concentration (SIC) decline during the 1979-2011 winter over the Atlantic sector. Furthermore, we find that the Arctic downward IR increase is driven by horizontal atmospheric water flux and warm air advection into the Arctic, and not by evaporation and surface heat flux from the Arctic Ocean. These horizontal heat fluxes are linked to La-Nina-like tropical convection. In all CMIP5 climate models that are analyzed here, high pattern correlations are found between the surface air temperature trend and downward IR trend. However, there are two groups of CMIP5 models: one with small correlations between the Arctic surface air temperature trend and the surface heat flux trend (Group 1), and the other with large correlations (Group 2) between the same two variables. There is evidence that the Group 1 models are consistent with the aforementioned observation-based finding that the Arctic warming is closely related to large-scale circulation changes. In contrast, the Group 2 models are at odds with this observation in that their Arctic warming is more closely tied to surface heat fluxes than with the large-scale circulation change. Interestingly, while Group 1 models have a warm or weak bias, Group 2 models have large cold biases in the Arctic. This difference suggests that deficiencies that cause the cold bias of the mean state may contribute to the surface heat

  13. Human Biogeography and Climate Change in Siberia and Arctic North America in the Fourth and Fifth Millennia BP

    NASA Astrophysics Data System (ADS)

    Powers, W. R.; Jordan, R. H.

    1990-04-01

    This paper explores the relation between the geographic shifts in prehistoric hunting populations and changes in climate between 4500 and 3000 before present (BP) within the polar regions from the Yenisei River in Siberia to Greenland. We have chosen this time period because major human geographic changes occurred over much of northeastern Asia and northern North America, and because these changes appear to be linked, at least in part, to a palaeoclimatic fluctuations. The cultures under consideration have been termed the Early and Middle Neolithic (Syalakh and Bel'kachi) in Siberia and the Arctic Small Tool Tradition (with such local variants as Denbigh, Independence I, Pre-Dorset, and Sarqaq) in North America. Despite these terminological differences, these groups shared such a close similarity in their technology and adaptive patterns that they must have once shared a direct historical relation.

  14. Arctic Ocean

    NASA Technical Reports Server (NTRS)

    Parkinson, Claire L.; Zukor, Dorothy J. (Technical Monitor)

    2000-01-01

    The Arctic Ocean is the smallest of the Earth's four major oceans, covering 14x10(exp 6) sq km located entirely within the Arctic Circle (66 deg 33 min N). It is a major player in the climate of the north polar region and has a variable sea ice cover that tends to increase its sensitivity to climate change. Its temperature, salinity, and ice cover have all undergone changes in the past several decades, although it is uncertain whether these predominantly reflect long-term trends, oscillations within the system, or natural variability. Major changes include a warming and expansion of the Atlantic layer, at depths of 200-900 m, a warming of the upper ocean in the Beaufort Sea, a considerable thinning (perhaps as high as 40%) of the sea ice cover, a lesser and uneven retreat of the ice cover (averaging approximately 3% per decade), and a mixed pattern of salinity increases and decreases.

  15. Arctic hydroclimatology

    NASA Astrophysics Data System (ADS)

    Cherry, Jessica Ellen

    Arctic air temperature, precipitation, ground temperature, river runoff, clouds, and radiation are all changing quickly in a warming climate. Interactions and feedbacks between these features are not well understood. In particular, the relative role of local climate processes and large-scale ocean-atmosphere dynamics in driving observed Arctic changes is difficult to ascertain because of the sparsity of observations, inaccuracy of those that do exist, biases in global circulation models and analyses, and fundamental physics of the Arctic region. Four studies of Arctic hydroclimatology herein attempt to overcome these challenges. The first study, analysis of the Lena river basin hydroclimatology, shows canonical acceleration of the hydrologic cycle and amplification of global warming. Winter and spring are warming and increased frozen precipitation is contributing to permafrost melting by increasing soil insulation. Increasing runoff and soil moisture is leading to increasing evapotranspiration and changes in clouds. Changes in clouds are cooling summer days but warming summer nights, melting additional permafrost. Model simulations suggests that a deepening active layer will lead to an increasingly wet Arctic. The second two studies describe the development of the Pan-Arctic Snowfall Reconstruction (PASR). This product addresses the problem of cold season precipitation gauge biases for 1940-1999. The NASA Interannual-to-Seasonal Prediction Project Catchment-based Land Surface Model is used to reconstruct solid precipitation from observed snow depth and surface air temperatures. Error estimation is done via controlled simulations at Reynolds Creek Experimental Watershed, in Idaho. The method is then applied to stations in the pan-Arctic hydrological catchment. Comparison with existing products suggests that the PASR is a better estimate of actual snowfall for hydroclimatological studies. The final chapter is a case study on hydroclimatological variability driven by

  16. Factors Affecting the Sensitivity of Permafrost to Climate Change

    NASA Astrophysics Data System (ADS)

    Jorgenson, T.; Romanovsky, V.; Harden, J.; Shur, Y.; Hinzman, L.; Marchenko, S.; Bolton, R.; O'Donnell, J.

    2009-05-01

    Permafrost aggradation and degradation are affected by numerous geomorphological and ecological properties of the landscape that confound our ability to accurately predict the response of permafrost to climate change. Permafrost can persist at mean annual air temperatures (MAAT) of +2 °C and can degrade at MAAT of -15 °C with the help of surface water. Permafrost is decoupled from the atmosphere by the active layer, thus, its thermal regime is mediated by numerous factors such as topography, soil texture, organic-matter accumulation, vegetation, snow, surface water, groundwater movement, and disturbance. Topography affects the amount of solar radiation to the soil surface, causing permafrost in the discontinuous zone to occur generally on north-facing slopes that receive less direct radiation and on flat, low- lying areas where vegetation and organic soils have a greater insulating effect and where air temperatures tend to be colder during winter inversions. Soil texture affects soil moisture and thermal properties. For instance, gravelly soils tend to be well-drained with little difference between thermal conductivities when frozen or thawed. In contrast, surface organic soils, as well as clayey and silty soils, in lowland areas tend to be poorly drained and have much higher thermal conductivities when frozen in winter than unfrozen in summer. In well- drained upland sites, however, organic soils typically are well below saturation. Differences in frozen and unfrozen thermal conductivities lead to more rapid heat loss in winter, depending on snow, and slower heat penetration in summer. Vegetation has important effects through interception of solar radiation, growth of mosses, accumulation of organic matter, and interception of snow by trees and shrubs. Snow protects soil from cooling in winter. Thus, the seasonality (e.g., timing of snowfall in early winter) and depth of snow are very important. Surface water provides an important positive feedback that enhances

  17. Radiocarbon age-offsets in an arctic lake reveal the long-term response of permafrost carbon to climate change

    USGS Publications Warehouse

    Gaglioti, Benjamin V.; Mann, Daniel H.; Jones, Benjamin M.; Pohlman, John W.; Kunz, Michael L.; Wooller, Matthew J.

    2014-01-01

    Continued warming of the Arctic may cause permafrost to thaw and speed the decomposition of large stores of soil organic carbon (OC), thereby accentuating global warming. However, it is unclear if recent warming has raised the current rates of permafrost OC release to anomalous levels or to what extent soil carbon release is sensitive to climate forcing. Here we use a time series of radiocarbon age-offsets (14C) between the bulk lake sediment and plant macrofossils deposited in an arctic lake as an archive for soil and permafrost OC release over the last 14,500 years. The lake traps and archives OC imported from the watershed and allows us to test whether prior warming events stimulated old carbon release and heightened age-offsets. Today, the age-offset (2 ka; thousand of calibrated years before A.D. 1950) and the depositional rate of ancient OC from the watershed into the lake are relatively low and similar to those during the Younger Dryas cold interval (occurring 12.9–11.7 ka). In contrast, age-offsets were higher (3.0–5.0 ka) when summer air temperatures were warmer than present during the Holocene Thermal Maximum (11.7–9.0 ka) and Bølling-Allerød periods (14.5–12.9 ka). During these warm times, permafrost thaw contributed to ancient OC depositional rates that were ~10 times greater than today. Although permafrost OC was vulnerable to climate warming in the past, we suggest surface soil organic horizons and peat are presently limiting summer thaw and carbon release. As a result, the temperature threshold to trigger widespread permafrost OC release is higher than during previous warming events.

  18. 2.8 Million Years of Arctic Climate Change from Deep Drilling at Lake El'gygytgyn, NE Russia

    NASA Astrophysics Data System (ADS)

    Melles, M.; Brigham-Grette, J.; Minyuk, P.; Wennrich, V.; Nowaczyk, N.; DeConto, R.; Anderson, P.; Andreev, A.; Haltia-Hovi, E.; Kukkonen, M.; Lozhkin, A.; Rosén, P.; Tarasov, P.

    2012-12-01

    Scientific deep drilling at Lake El'gygtygyn in Chukotka, northeastern Russia (67.5 °N, 172 °E) revealed the first high-resolution record of environmental history in the Arctic that spans the past 2.8 Ma continuously (Melles et al. 2012). In this presentation we focus on the end-member glacial and interglacial climatic conditions during this period as clearly reflected in the pelagic lake sediments recovered. Peak glacial conditions, when mean annual air temperatures at least 4 (± 0.5) °C lower than today led to perennial lake ice (Nolan 2012), first appeared at Lake El'gygytgyn 2.602 - 2.598 Ma ago, during marine isotope stage (MIS) 104. These pervasive glacial episodes gradually increase in frequency from ~2.3 to ~1.8 Ma, eventually concurring with all glacials and several stadials reflected globally in stacked marine isotope records. Particularly warm interglacials, in contrast, experienced a long ice-free season and enhanced nutrient supply from the catchment, which allowed for significantly higher primary production than today. These settings were most pronounced for MIS 11c, 31, 49, 55, 77, 87, 91, and 93. Their exceptional character becomes evident based upon pollen-based climate reconstructions in selected interglacials, showing that the mean temperature of the warmest month and the annual precipitation during the thermal maxima of MIS 11c and 31 ("super" interglacials) were 4-5 °C and ~300 mm higher than those of MIS 1 and 5e ("normal" interglacials), respectively. According to climate simulations, the exceptional warm and moist climates at least during MIS 11c cannot be explained by the natural variability in Earth's orbital parameters and greenhouse gas concentrations alone. A remarkable coincidence of the super interglacials at Lake El'gygytgyn with diatomite layers in the Antarctic ANDRILL 1B, which reflect periods of a diminished West Antarctic Ice Sheet (WAIS) (Naish et al. 2009, Pollard and DeConto 2009), suggests intra-hemispheric climate

  19. Enhanced 20th century heat transfer to the Arctic simulated in the context of climate variations over the last millennium

    NASA Astrophysics Data System (ADS)

    Jungclaus, J. H.; Zanchettin, D.; Chamarro, E. M.; Lohmann, K.

    2013-12-01

    Paleoceanographic reconstructions have revealed recent changes in oceanic heat transport into the Arctic that are unprecedented over the past 2000 to 3000 years [Spielhagen et al., 2011; Dylmer et al., 2013]. The 20th century increase in heat transport is related to intensified Atlantic Water advection and manifests itself in terms of changes in foraminiferal assemblages and geochemical tracers. Here we present results from an ensemble of three simulations covering the last millennium (850 - 2005 CE). The experiments were conducted in the framework of PMIP3/CMIP5 using the Max Planck Institute Earth System Model for paleo applications (MPI-ESM-P). The model features the same grids (ECHAM6: T63/L47, MPIOM:1.5°/L40) as the standard CMIP5 model (MPI-ESM-LR [Jungclaus et al., 2013]) but does not include dynamic vegetation. External forcings are applied following the PMIP3 protocol [Schmidt et al., 2011]. Combining forced simulations over pre-industrial times with those over the last 150 years enables us to put changes observed in the modern period in context with a period where only natural forcing agents were active. Additional long unperturbed control simulations serve to discriminate between forced and internally-generated variability. For the northward oceanic heat transports in the northern North Atlantic and in the Nordic Seas all simulations show pronounced multi-centennial variations and an unprecedented increase in the 20th century. The changes in heat transport can be traced back to changes in the gyre circulation in the subpolar North Atlantic with some local amplification. We investigate the reason for the changes in ocean circulation and atmospheric variability modes and discuss the implications for the role of ocean lateral transports for Arctic amplification of global climate change. Dylmer, C.V. et al. [2013], Northward advection of Atlantic water in the eastern Nordic Seas over the last 3000yr., Clim. Past., 9, 1505-1518. Jungclaus, J.H. et al. [2013

  20. Paleoeskimo Demographic History in the Canadian Arctic (ca. 4800-800 B.P.) and its Relationship to Mid-Late Holocene Climate Variability.

    NASA Astrophysics Data System (ADS)

    Savelle, J. M.

    2014-12-01

    Paleoeskimos were the first occupants of the central and eastern Canadian Arctic, spreading east from the Bering Strait region beginning approximately 4800 B.P., and occupied much of the Canadian Arctic through to their eventual disappearance ca. 800 B.P. Extensive regional archaeological site surveys throughout this area by the author and Arthur S. Dyke indicate that Paleoskimo populations underwent a series of population 'boom' (rapid expansion) and 'bust' (population declines and local extinctions) over the 4,000 year occupation history, including in the purported stable 'core area' of Foxe Basin. In this paper, we examine the contemporaneity of the local boom and bust cycles in a pan-Canadian Arctic context, and in turn examine the relationship of these cycles to mid-late Holocene climate variability.