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.
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.
Lenton, Timothy M
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.
Gutowski, William J.
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.
Hansen, Brage B; Grøtan, Vidar; Aanes, Ronny; Sæther, Bernt-Erik; Stien, Audun; Fuglei, Eva; Ims, Rolf A; Yoccoz, Nigel G; Pedersen, Ashild Ø
Recently accumulated evidence has documented a climate impact on the demography and dynamics of single species, yet the impact at the community level is poorly understood. Here, we show that in Svalbard in the high Arctic, extreme weather events synchronize population fluctuations across an entire community of resident vertebrate herbivores and cause lagged correlations with the secondary consumer, the arctic fox. This synchronization is mainly driven by heavy rain on snow that encapsulates the vegetation in ice and blocks winter forage availability for herbivores. Thus, indirect and bottom-up climate forcing drives the population dynamics across all overwintering vertebrates. Icing is predicted to become more frequent in the circumpolar Arctic and may therefore strongly affect terrestrial ecosystem characteristics.
Hovinen, Johanna E H; Welcker, Jorg; Descamps, Sébastien; Strøm, Hallvard; Jerstad, Kurt; Berge, Jørgen; Steen, Harald
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
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
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.
Descamps, Sébastien; Aars, Jon; Fuglei, Eva; Kovacs, Kit M; Lydersen, Christian; Pavlova, Olga; Pedersen, Åshild Ø; Ravolainen, Virve; Strøm, Hallvard
The Arctic is warming more rapidly than other region on the planet, and the northern Barents Sea, including the Svalbard Archipelago, is experiencing the fastest temperature increases within the circumpolar Arctic, along with the highest rate of sea ice loss. These physical changes are affecting a broad array of resident Arctic organisms as well as some migrants that occupy the region seasonally. Herein, evidence of climate change impacts on terrestrial and marine wildlife in Svalbard is reviewed, with a focus on bird and mammal species. In the terrestrial ecosystem, increased winter air temperatures and concomitant increases in the frequency of 'rain-on-snow' events are one of the most important facets of climate change with respect to impacts on flora and fauna. Winter rain creates ice that blocks access to food for herbivores and synchronizes the population dynamics of the herbivore-predator guild. In the marine ecosystem, increases in sea temperature and reductions in sea ice are influencing the entire food web. These changes are affecting the foraging and breeding ecology of most marine birds and mammals and are associated with an increase in abundance of several temperate fish, seabird and marine mammal species. Our review indicates that even though a few species are benefiting from a warming climate, most Arctic endemic species in Svalbard are experiencing negative consequences induced by the warming environment. Our review emphasizes the tight relationships between the marine and terrestrial ecosystems in this High Arctic archipelago. Detecting changes in trophic relationships within and between these ecosystems requires long-term (multidecadal) demographic, population- and ecosystem-based monitoring, the results of which are necessary to set appropriate conservation priorities in relation to climate warming.
Cronin, T.; Tziperman, E.; Li, H.
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
Lettenmaier, Dennis P
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.
Hobbie, John E; Shaver, Gaius R; Rastetter, Edward B; Cherry, Jessica E; Goetz, Scott J; Guay, Kevin C; Gould, William A; Kling, George W
Long-term measurements of ecological effects of warming are often not statistically significant because of annual variability or signal noise. These are reduced in indicators that filter or reduce the noise around the signal and allow effects of climate warming to emerge. In this way, certain indicators act as medium pass filters integrating the signal over years-to-decades. In the Alaskan Arctic, the 25-year record of warming of air temperature revealed no significant trend, yet environmental and ecological changes prove that warming is affecting the ecosystem. The useful indicators are deep permafrost temperatures, vegetation and shrub biomass, satellite measures of canopy reflectance (NDVI), and chemical measures of soil weathering. In contrast, the 18-year record in the Greenland Arctic revealed an extremely high summer air-warming of 1.3 °C/decade; the cover of some plant species increased while the cover of others decreased. Useful indicators of change are NDVI and the active layer thickness.
Shin, Yechul; Kang, Sarah M.; Watanabe, Masahiro
Previous studies suggest large uncertainties in the stationary wave response under global warming. Here, we investigate how the Arctic climate responds to changes in the latitudinal position of stationary waves, and to high-latitudes surface warming that mimics the effect of Arctic sea ice loss under global warming. To generate stationary waves in an atmospheric model coupled to slab ocean, a series of experiments is performed where the thermal forcing with a zonal wavenumber-2 (with zero zonal-mean) is prescribed at the surface at different latitude bands in the Northern Hemisphere. When the stationary waves are generated in the subtropics, the cooling response dominates over the warming response in the lower troposphere due to cloud radiative effects. Then, the low-level baroclinicity is reduced in the subtropics, which gives rise to a poleward shift of the eddy driven jet, thereby inducing substantial cooling in the northern high latitudes. As the stationary waves are progressively generated at higher latitudes, the zonal-mean climate state gradually becomes more similar to the integration with no stationary waves. These differences in the mean climate affect the Arctic climate response to high-latitudes surface warming. Additional surface heating over the Arctic is imposed to the reference climates in which the stationary waves are located at different latitude bands. When the stationary waves are positioned at lower latitudes, the eddy driven jet is located at higher latitude, closer to the prescribed Arctic heating. As baroclinicity is more effectively perturbed, the jet shifts more equatorward that accompanies a larger reduction in the poleward eddy transport of heat and momentum. A stronger eddy-induced descending motion creates greater warming over the Arctic. Our study calls for a more accurate simulation of the present-day stationary wave pattern to enhance the predictability of the Arctic warming response in a changing climate.
Maseyk, K. S.; Welker, J. M.; Czimczik, C. I.; Lupascu, M.; Lett, C.; Seibt, U. H.
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.
Galloway, Jennifer M.; Tullius, Dylan N.; Evenchick, Carol A.; Swindles, Graeme T.; Hadlari, Thomas; Embry, Ashton
Understanding the behaviour of global climate during relatively warm periods in Earth's history, such as the Cretaceous Period, advances our overall understanding of the climate system and provides insight on drivers of climate change over geologic time. While it has been suggested that the Valanginian Age represents the first episode of Cretaceous greenhouse climate conditions with relatively equable warm temperatures, mounting evidence suggests that this time was relatively cool. A paucity of paleoclimate data currently exists for polar regions compared to mid- and low-latitudes and this is particularly true for the Canadian Arctic. There is also a lack of information about the terrestrial realm as most paleoclimate studies have been based on marine material. Here we present quantitative pollen and spore data obtained from the marginal marine and deltaic-fluvial Isachsen Formation of the Sverdrup Basin, Canadian Arctic, to better understand the long-term vegetation and climate history of polar regions during the warm but variable Early Cretaceous (Valanginian to Early Aptian). Detrended correspondence analysis of main pollen and spore taxa is used to derive three ecological groupings influenced by moisture and disturbance based on the botanical affinities of palynomorphs: 1) a mixed coniferous assemblage containing both lowland and upland components; 2) a conifer-filicopsid community that likely grew in dynamic lowland habitats; and, 3) a mature dry lowland community composed of Cheirolepidaceans. Stratigraphic changes in the relative abundance of pollen and spore taxa reflect climate variability in this polar region during the ~20 Mya history of the Isachsen Formation. The late Valanginian was relatively cool and moist and promoted lowland conifer-filicopsid communities. Warming in the Hauterivian resulted in the expansion coniferous communities in well-drained or arid hinterlands. A return to relatively cool and moist conditions in the Barremian resulted in the
Bono, Richard K.; Clarke, Julia; Tarduno, John A.; Brinkman, Donald
Bird fossils from Turonian (ca. 90 Ma) sediments of Axel Heiberg Island (High Canadian Arctic) are among the earliest North American records. The morphology of a large well-preserved humerus supports identification of a new volant, possibly diving, ornithurine species (Tingmiatornis arctica). The new bird fossils are part of a freshwater vertebrate fossil assemblage that documents a period of extreme climatic warmth without seasonal ice, with minimum mean annual temperatures of 14 °C. The extreme warmth allowed species expansion and establishment of an ecosystem more easily able to support large birds, especially in fresh water bodies such as those present in the Turonian High Arctic. Review of the high latitude distribution of Northern Hemisphere Mesozoic birds shows only ornithurine birds are known to have occupied these regions. We propose physiological differences in ornithurines such as growth rate may explain their latitudinal distribution especially as temperatures decline later in the Cretaceous. Distribution and physiology merit consideration as factors in their preferential survival of parts of one ornithurine lineage, Aves, through the K/Pg boundary. PMID:27991515
Bono, Richard K; Clarke, Julia; Tarduno, John A; Brinkman, Donald
Bird fossils from Turonian (ca. 90 Ma) sediments of Axel Heiberg Island (High Canadian Arctic) are among the earliest North American records. The morphology of a large well-preserved humerus supports identification of a new volant, possibly diving, ornithurine species (Tingmiatornis arctica). The new bird fossils are part of a freshwater vertebrate fossil assemblage that documents a period of extreme climatic warmth without seasonal ice, with minimum mean annual temperatures of 14 °C. The extreme warmth allowed species expansion and establishment of an ecosystem more easily able to support large birds, especially in fresh water bodies such as those present in the Turonian High Arctic. Review of the high latitude distribution of Northern Hemisphere Mesozoic birds shows only ornithurine birds are known to have occupied these regions. We propose physiological differences in ornithurines such as growth rate may explain their latitudinal distribution especially as temperatures decline later in the Cretaceous. Distribution and physiology merit consideration as factors in their preferential survival of parts of one ornithurine lineage, Aves, through the K/Pg boundary.
Bono, Richard K.; Clarke, Julia; Tarduno, John A.; Brinkman, Donald
Bird fossils from Turonian (ca. 90 Ma) sediments of Axel Heiberg Island (High Canadian Arctic) are among the earliest North American records. The morphology of a large well-preserved humerus supports identification of a new volant, possibly diving, ornithurine species (Tingmiatornis arctica). The new bird fossils are part of a freshwater vertebrate fossil assemblage that documents a period of extreme climatic warmth without seasonal ice, with minimum mean annual temperatures of 14 °C. The extreme warmth allowed species expansion and establishment of an ecosystem more easily able to support large birds, especially in fresh water bodies such as those present in the Turonian High Arctic. Review of the high latitude distribution of Northern Hemisphere Mesozoic birds shows only ornithurine birds are known to have occupied these regions. We propose physiological differences in ornithurines such as growth rate may explain their latitudinal distribution especially as temperatures decline later in the Cretaceous. Distribution and physiology merit consideration as factors in their preferential survival of parts of one ornithurine lineage, Aves, through the K/Pg boundary.
Stone, R.S.; Douglas, David C.; Belchansky, G.I.; Drobot, S.D.
Recent decreases in snow and sea ice cover in the high northern latitudes are among the most notable indicators of climate change. Northern Hemisphere sea ice extent for the year as a whole was the third lowest on record dating back to 1973, behind 1995 (lowest) and 1990 (second lowest; Hadley Center–NCEP). September sea ice extent, which is at the end of the summer melt season and is typically the month with the lowest sea ice extent of the year, has decreased by about 19% since the late 1970s (Fig. 5.2), with a record minimum observed in 2002 (Serreze et al. 2003). A record low extent also occurred in spring (Chapman 2005, personal communication), and 2004 marked the third consecutive year of anomalously extreme sea ice retreat in the Arctic (Stroeve et al. 2005). Some model simulations indicate that ice-free summers will occur in the Arctic by the year 2070 (ACIA 2004).
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.
Bjorkman, Anne D; Vellend, Mark; Frei, Esther R; Henry, Gregory H R
Rapidly rising temperatures are expected to cause latitudinal and elevational range shifts as species track their optimal climate north and upward. However, a lack of adaptation to environmental conditions other than climate - for example photoperiod, biotic interactions, or edaphic conditions - might limit the success of immigrants in a new location despite hospitable climatic conditions. Here, we present one of the first direct experimental tests of the hypothesis that warmer temperatures at northern latitudes will confer a fitness advantage to southern immigrants relative to native populations. As rates of warming in the Arctic are more than double the global average, understanding the impacts of warming in Arctic ecosystems is especially urgent. We established experimentally warmed and nonwarmed common garden plots at Alexandra Fiord, Ellesmere Island in the Canadian High Arctic with seeds of two forb species (Oxyria digyna and Papaver radicatum) originating from three to five populations at different latitudes across the Arctic. We found that plants from the local populations generally had higher survival and obtained a greater maximum size than foreign individuals, regardless of warming treatment. Phenological traits varied with latitude of the source population, such that southern populations demonstrated substantially delayed leaf-out and senescence relative to northern populations. Our results suggest that environmental conditions other than temperature may influence the ability of foreign populations and species to establish at more northerly latitudes as the climate warms, potentially leading to lags in northward range shifts for some species.
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
Amann, Benjamin; Lamoureux, Scott F.
The Arctic is extremely sensitive to climate change, and an influential part of the global climate system. However, the assessment of climate change and impacts from the Arctic remains a challenge mainly due to short and sparse meteorological records. In this context, data from natural paleoclimate archives are fundamental to place climate variability into perspective and assess the sensitivity of Earth's climate to natural and anthropogenic forcings. In particular, Arctic lakes are excellent potential archives. They are sensitive to extreme seasonal variations in surface processes and have a limited direct human impact. Nevertheless, the study of Arctic lakes is an analytical and technical challenge because: (i) limnological information are often lacking due to difficult accessibility; (ii) 210Pb inventories are low and terrestrial macrofossils for 14C dating are rare, which limits the development of precise sediment chronologies; and (iii) sediment accumulation rates are often low, which may restrict the temporal resolution and length of the paleoclimate records. Here, we present a high-resolution record from the varved sediments (annual laminations) of a saline coastal lake located in the Canadian High Arctic (unofficial name Chevalier Lake; Melville Island, NT). The particular interest of this location is the catchment area: 152 times larger than the lake area (Ac = 350 km²; AL = 2.3 km²). This particularity generates high sedimentation rates, atypical of previously studied arctic lakes. Two sediment cores were recovered from the centre and a more proximal zone of the lake. We used microstratigraphy supported by X-ray fluorescence data (Zr/K for particle size, Fe/Rb for the winter clay cap distinction) to develop a precise and cross-dated varve chronology covering the last 400 years. Dating of the uppermost section could be validated with preliminary 137Cs data. Stratigraphical analysis reveals the presence of three sediment units within the meter
Rhines, P. B.
The passages connecting the Arctic Ocean with the Atlantic and Pacific, and their `mediterranean' basins, are focal points for the global meridional overturning circulation, and all of the climate impacts which this implies. It is also a difficult region to model accurately: the sensitivity of climate models to subpolar ocean dynamics is well-known. In this talk we stress the need to instrument and analyze the subpolar oceans, and some examples of sustained observations developing there. Results from satellite altimetry, recent Seaglider deployments from Greenland, and mooring arrays will be described. In particular we show the first Seaglider sections of hydrography and bio-optical profiles of the Labrador Sea (one of the first extended deployments of this autonomous undersea vehicle); we discuss the decline during the 1990s of the subpolar gyre circulation of the Atlantic from its great strength during the positive NAO period of the early 1990s, and its relevance to the salinity decline observed over a much longer period; we review observations of the flows at the Iceland-Scotland Ridge and Davis Strait, argued in terms of volume transport plots on the potential temperature/salinity plane; we display maps of the `convection resistance' (related to dynamic height) and its sensitivity to surface low-salinity water masses and their partition between shallow continental shelves and deep ocean. This is a particularly exciting time for climate studies, with fundamental properties of the atmosphere-ocean circulation under debate, even before one considers natural and human-induced variability. Is the four-decade long decline in subArctic salinity the result of increased hydrologic cycle, increased or altered Arctic outflow to the Atlantic, or slowing of the subpolar circulation? Is the basic intensity of the MOC more dependent on high-latitude buoyancy forcing, or wind- or tide-driven mixing in the upwelling branch, or possibly wind-stress at high latitude? Is the
Hougham, R. J.; Miller, B.; Cox, C. J.
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
Chylek, Petr; Dubey, Manvendra K; Lesins, Glen; Wang, Muyin
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.
McGuire, A.D.; Chapin, F. S.; Walsh, J.E.; Wirth, C.; ,
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.
Corell, Robert W
Climate change is being experienced particularly intensely in the Arctic. Arctic average temperature has risen at almost twice the rate as that of the rest of the world in the past few decades. Widespread melting of glaciers and sea ice and rising permafrost temperatures present additional evidence of strong Arctic warming. These changes in the Arctic provide an early indication of the environmental and societal significance of global consequences. The Arctic also provides important natural resources to the rest of the world (such as oil, gas, and fish) that will be affected by climate change, and the melting of Arctic glaciers is one of the factors contributing to sea level rise around the globe. An acceleration of these climatic trends is projected to occur during this century, due to ongoing increases in concentrations of greenhouse gases in the Earth's atmosphere. These Arctic changes will, in turn, impact the planet as a whole.
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
Curtis, J. B.; Serbin, S.; Dafflon, B.; Raz Yaseef, N.; Torn, M. S.; Cook, P. J.; Lewin, K. F.; Wullschleger, S. D.
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
Mottram, Ruth; Langen, Peter; Koldtoft, Iben; Midefelt, Linnea; Hesselbjerg Christensen, Jens
Globally, small ice caps and glaciers make a substantial contribution to sea level rise; this is also true in the Arctic. Around Greenland small ice caps are surprisingly important to the total mass balance from the island as their marginal coastal position means they receive a large amount of precipitation and also experience high surface melt rates. Since small ice caps and glaciers have had a disproportionate number of long-term monitoring and observational schemes in the Arctic, likely due to their relative accessibility, they can also be a valuable source of data. However, in climate models the surface mass balance contributions are often not distinguished from the main ice sheet and the presence of high relief topography is difficult to capture in coarse resolution climate models. At the same time, the diminutive size of marginal ice masses in comparison to the ice sheet makes modelling their ice dynamics difficult. Using observational data from the Devon Ice Cap in Arctic Canada and the Renland Ice Cap in Eastern Greenland, we assess the success of a very high resolution (~5km) regional climate model, HIRHAM5 in capturing the surface mass balance (SMB) of these small ice caps. The model is forced with ERA-Interim and we compare observed mean SMB and the interannual variability to assess model performance. The steep gradient in topography around Renland is challenging for climate models and additional statistical corrections are required to fit the calculated surface mass balance to the high relief topography. Results from a modelling experiment at Renland Ice Cap shows that this technique produces a better fit between modelled and observed surface topography. We apply this statistical relationship to modelled SMB on the Devon Ice Cap and use the long time series of observations from this glacier to evaluate the model and the smoothed SMB. Measured SMB values from a number of other small ice caps including Mittivakkat and A.P. Olsen ice cap are also compared
Tilmes, S.; Jahn, Alexandra; Kay, Jennifer E.; Holland, Marika; Lamarque, Jean-Francois
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.
MacLachlan, S. E.; Howe, J.
The cryosphere is a crucial component of the Earth's climate system, and comprises sea ice, snow, glaciers, ice cap, ice shelves, river and lake ice, ice sheets and frozen ground. The cryosphere has shown ice growth and decay on many timescales associated both with 100,000 year ice age cycles and with shorter-term (<2000 yrs) variations such as the Younger Dryas and the Little Ice Age. Crucially the cyosphere acts as a barometer for climate change because it provides a visible means of assessing the impacts of recent climate warming. Coastal Arctic regions are particularly sensitive to climate change, and records of glacier fluctuations can be used to infer past climate. The western Svalbard margin is a climatically sensitive region presently influenced by the warm and saline Atlantic water of the West Spitsbergen Current. This current is the northernmost extension of the Norwegian Atlantic Current that transports significant quantities of heat northward, maintaining the seas west of the Svalbard shelf increasingly ice free. For the Svalbard area there are currently a number of low-resolution (centennial to multi-decadal) marine records that span the Holocene. Despite their low resolution, several studies have highlighted abrupt environmental shifts and fluctuating glacial conditions during the Holocene. A few low-resolution lake records and other sporadic terrestrial datasets also exist providing a limited insight into the terrestrial environmental changes over the last two millennia. We have generated the first sub-decadal resolution late Holocene climatic record, in order to determine the nature and timing of environmental changes across transient climate events at an unprecedented temporal scale for this region. XRF analyses provides the high-resolution data series, which has been integrated with sedimentological data to better define the environmental processes; thus providing the basis for the reconstruction of climate change in this glaciated fjordic
Potential increase in Humanitarian Assistance/Disaster Response Wild-cards Ocean acidification Abrupt climate change Geoengineering Challenges and...Content from 1950 (Murphy 2009). Ocean data taken from Domingues et al 2008 The Ocean is Storing Most of the Heat Mean surface temperature 2001-2007...UNCLASSIFIED 8 Arctic Considerations One Scenario Native Perspectives The Arctic is an ocean , a challenge, but NOT a vacuum + = Unalakleet, 2040Gulf Coast
Bintanja, R; van der Linden, E C
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.
Backus, George A.; Strickland, James Hassler
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.
Principal Components Analysis in T-Mode Varimax rotated was performed on Antarctic and Arctic monthly sea ice concentration anomalies (SICA) fields for the period 1979-2014, in order to investigate which are the main spatial characteristics of sea ice and its relationship with atmospheric circulation. This analysis provides 5 patterns of sea ice for inter-spring period and 3 patterns for summer-autumn for Antarctica (69,2% of the total variance) and 3 different patterns for summer-autumn and 3 for winter-spring season for the Arctic Ocean (67,8% of the total variance).Each of these patterns has a positive and negative phase. We used the Monthly Polar Gridded Sea Ice Concentrations database derived from satellite information generated by NASA Team algorithm. To understand the links between the SICA and climate trends, we extracted the mean pressure and, temperature field patterns for the months with high loadings (positive or negative) of the sea ice patterns that gave distinct atmospheric structures associated with each one. For Antarctica, the first SICA spatial winter-spring pattern in positive phase shows a negative SICA centre over the Drake Passage and north region of Bellingshausen and Weddell Seas together with another negative SICA centre over the East Indian Ocean. Strong positive centres over the rest of the Atlantic and Indian Oceans basins and the Amundsen Sea are also presented. A strong negative pressure anomaly covers most of the Antarctic Continent centered over the Bellingshausen Sea accompanied by three positive pressure anomalies in middle-latitudes. During recent years, the Arctic showed persistent associations of sea-ice and climate patterns principally during summer. Our strongest summer-autumn pattern in negative phase showed a marked reduction on SICA over western Arctic, primarily linked to an overall increase in Arctic atmospheric temperature most pronounced over the Beaufort, Chukchi and East Siberian Seas, and a positive anomaly of
Hodson, Daniel L. R.; Keeley, Sarah P. E.; West, Alex; Ridley, Jeff; Hawkins, Ed; Hewitt, Helene T.
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.
Lund, M.; Hansen, B. U.; Pedersen, S. H.; Stiegler, C.; Tamstorf, M. P.
During recent decades the observed warming in the Arctic has been almost twice as large as the global average. The implications of such strong warming on surface energy balance, regulating permafrost thaw, hydrology, soil stability and carbon mineralization, need to be assessed. In Zackenberg, northeast Greenland, measurements of energy balance components in various environments have been performed since late 90's, coordinated by Zackenberg Ecological Research Operations. During 1996-2009, mean annual temperature in the area has increased by ca. 0.15 °C yr-1; while maximum thaw depth has increased by 1.4-1.8 cm yr-1. Eddy covariance measurements of energy fluxes have been performed in a Cassiope heath plant community, a commonly occurring tundra ecosystem type in circumpolar middle and high Arctic areas, in Zackenberg allowing for detailed investigations of relationships between energy fluxes and meteorological and soil physical characteristics. As the available data set spans more than a decade, possible trends in energy flux components resulting from warming related changes such as earlier snow melt, increased active layer depth and higher temperatures can be investigated. This presentation will focus on the mid-summer period from which eddy covariance measurements are available. The summer-time energy partitioning at the Zackenberg tundra heath site will be characterized using ratios of sensible, latent and ground heat flux to net radiation and Bowen ratio, whereas the surface characteristics will be described using surface resistance, McNaughton and Jarvis Ω value and Priestley-Taylor α coefficient. Furthermore, we aim to estimate the full year, all energy balance components for the tundra heath site using Snow Model (Liston and Elder 2006) for the dark winter period during which no eddy covariance measurements are available. The snow cover duration in the area is a major regulator of the energy partitioning. Early results point towards high summer
Lamoureux, S. F.; Normandeau, A.
High resolution lacustrine sedimentary sequences hold substantial potential for paleoenvironmental analyses, particularly in regions where few alternatives are available. Increased attention to quantifying processes that generate sedimentary facies has yielded increasingly detailed environmental interpretations but these efforts have been limited by available field data. The Cape Bounty Arctic Watershed Observatory (CBAWO) was initiated in 2003 to develop a long term site to evaluate the controls over sediment transport and the formation of clastic sedimentary records. This program in the Canadian Arctic has supported 13 years of research in paired watersheds and lakes, both of which contain clastic varves. Results from 2003-14 demonstrate how multiple climatic factors delivery sediment in a complex manner. This comparatively simple hydroclimatic system is dominated by runoff and sediment transport from spring snowmelt, with clear associations between catchment snow water equivalence (or total runoff) and sediment yield, with discharge limited by snow exhaustion as the season progresses. Major rainfall can constitute a dominant contribution to seasonal sediment yield, but antecedent conditions can significantly reduce runoff markedly. Hence, these results indicate two primary competing hydroclimatic factors that control catchment sediment yield, both with independent climatic and hydrological factors. Additionally, the impact of landscape disturbance on downstream sediment yield has been evaluated following a major episode of permafrost thaw in 2007. Results show that localized slope disturbances resulted in enhanced erosion but downstream fluvial storage reduced the magnitude of transport. Sediment from disturbances will be gradually released and may generate decadal-scale sediment delivery changes in the downstream record. Collectively, this research indicates multiple controls over the formation of clastic varves. Advances in high resolution sedimentary
Bigras, S. C.
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
Wrona, F. J.; Prowse, T. D.; Reist, J. D.
An overview is provided of the key findings of the Arctic Climate Impact Assessment (ACIA), which is an international project of the Arctic Council and the International Arctic Science Committee (IASC), to evaluate and synthesize knowledge on climate variability, climate change, and increased ultraviolet radiation and their consequences. Predicted changes in climate and UV in the Arctic are expected to have far-reaching impacts on the hydrology and ecology of freshwater ecosystems. Key effects include changes in the distribution, abundance and ecology of aquatic species in various trophic levels, dramatic alterations in the physical environment that makes up their habitat, changes to the chemical properties of that environment, and alterations to the processes that act on and within freshwater ecosystems. Interactions of climatic variables, such as temperature and precipitation, with freshwater ecosystems are highly complex and hence can be propagated through ecosystems in ways that are often difficult to predict. This is partly because of our still relatively poor understanding of the structure and function of arctic freshwater systems and their basic interrelationships with climate and other environmental variables, as well as by a paucity of long-term freshwater monitoring sites and integrated hydro-ecological research programs in the Arctic. Predictions of hydro-ecological impacts are further complicated by synergistic and cumulative effects.
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
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
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
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.
Alley, Richard B.; Brigham-Grette, Julie; Miller, Gifford H.; Polyak, Leonid; ,; ,; ,
Paleoclimate records play a key role in our understanding of Earth's past and present climate system and in our confidence in predicting future climate changes. Paleoclimate data help to elucidate past and present active mechanisms of climate change by placing the short instrumental record into a longer term context and by permitting models to be tested beyond the limited time that instrumental measurements have been available.
Serreze, M. C.
It was probably around the year 2000 when I had an epiphany. A realization, after years of sitting on the fence, that the changes unfolding in the Arctic were too persistent, and too coherent among different parts of the system, to be simply dismissed as natural climate fluctuations. Seven years have passed, and despite imprints of natural variability , the Arctic has continued along a warming path. The emerging surprise is the rapidity of change. In many ways, it seems that reality has exceeded expectations, and that our vision of the Arctic's future is already upon us. The most visually striking evidence of rapid change is the Arctic's shrinking sea ice cover. While climate models tell us that sea ice extent should already be declining in response to greenhouse gas loading, observed trends are much steeper - we are perhaps 30 years ahead of schedule. Climate models also tell us that largely as a result of sea ice loss, Arctic warming will be outsized compared to the rest of the northern hemisphere. However, this so-called Arctic Amplification is already here. The signal appears to be firm, and growing in strength. In turn, the Greenland ice sheet seems to be stirring in ways quite unexpected ten years ago, with disturbing implications for sea level rise. Why is the Arctic changing so rapidly? What are the missing pieces of the puzzle? Given where we stand today, might we realize a seasonally ice free Arctic Ocean as soon as 30 years from now? This Nye lecture will attempt to shed some light on these issues.
Wilkniss, P. E.
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
Walsh, John E
The climate of the Arctic marine environment is characterized by strong seasonality in the incoming solar radiation and by tremendous spatial variations arising from a variety of surface types, including open ocean, sea ice, large islands, and proximity to major landmasses. Interannual and decadal-scale variations are prominent features of Arctic climate, complicating the distinction between natural and anthropogenically driven variations. Nevertheless, climate models consistently indicate that the Arctic is the most climatically sensitive region of the Northern Hemisphere, especially near the sea ice margins. The Arctic marine environment has shown changes over the past several decades, and these changes are part of a broader global warming that exceeds the range of natural variability over the past 1000 years. Record minima of sea ice coverage during the past few summers and increased melt from Greenland have important implications for the hydrographic regime of the Arctic marine environment. The recent changes in the atmosphere (temperature, precipitation, pressure), sea ice, and ocean appear to be a coordinated response to systematic variations of the large-scale atmospheric circulation, superimposed on a general warming that is likely associated with increasing greenhouse gases. The changes have been sufficiently large in some sectors (e.g., the Bering/Chukchi Seas) that consequences for marine ecosystems appear to be underway. Global climate models indicate an additional warming of several degrees Celsius in much of the Arctic marine environment by 2050. However, the warming is seasonal (largest in autumn and winter), spatially variable, and closely associated with further retreat of sea ice. Additional changes predicted for 2050 are a general decrease of sea level pressure (largest in the Bering sector) and an increase of precipitation. While predictions of changes in storminess cannot be made with confidence, the predicted reduction of sea ice cover will
Wrona, Frederick J; Prowse, Terry D; Reist, James D; Hobbie, John E; Lévesque, Lucie M J; Vincent, Warwick F
Changes in climate and ultraviolet radiation levels in the Arctic will have far-reaching impacts, affecting aquatic species at various trophic levels, the physical and chemical environment that makes up their habitat, and the processes that act on and within freshwater ecosystems. Interactions of climatic variables, such as temperature and precipitation, with freshwater ecosystems are highly complex and can propagate through the ecosystem in ways that are difficult to project. This is partly due to a poor understanding of arctic freshwater systems and their basic interrelationships with climate and other environmental variables, and partly due to a paucity of long-term freshwater monitoring sites and integrated hydro-ecological research programs in the Arctic. The papers in this special issue are an abstraction of the analyses performed by 25 international experts and their associated networks on Arctic freshwater hydrology and related aquatic ecosystems that was initially published by the Arctic Climate Impact Assessment (ACIA) in 2005 as "Chapter 8--Freshwater Ecosystems and Fisheries". The papers provide a broad overview of the general hydrological and ecological features of the various freshwater ecosystems in the Arctic, including descriptions of each ACIA region, followed by a review of historical changes in freshwater systems during the Holocene. This is followed by an assessment of the effects of climate change on broad-scale hydro-ecology; aquatic biota and ecosystem structure and function; and arctic fish and fisheries. Potential synergistic and cumulative effects are also discussed, as are the roles of ultraviolet radiation and contaminants. The nature and complexity of many of the effects are illustrated using case studies from around the circumpolar north, together with a discussion of important threshold responses (i.e., those that produce stepwise and/or nonlinear effects). The issue concludes with summary the key findings, a list of gaps in
Galloway, Jennifer M.; Cooney, Darryl; Crann, Carley; Falck, Hendrik; Howell, Dana; Jamieson, Heather; Macumber, Andrew; Nasser, Nawaf; Palmer, Michael; Patterson, R. Timothy; Parsons, Michael; Roe, Helen M.; Sanei, Hamed; Spence, Christopher; Stavinga, Drew; Swindles, Graeme T.
Climate variability is occurring at unprecedented rates in northern regions of the Earth, yet little is known about the nature of this variability or its influence on chemical cycling in the environment, particularly in areas with a legacy of contamination from past resource development. We use a paleolimnological approach to reconstruct climate and chemical change over centuries and millennia at two sites in the mineral-rich Slave Geologic Province in Northern Canada heavily impacted by gold mining. Such an approach is necessary to define the cumulative effects of climate change on metal loading and can be used to define anthropogenic release of contaminants to support policy and regulation due to a paucity of long-term monitoring data. The Seabridge Gold Inc. Courageous Lake project is a gold exploration project 240 km north of Yellowknife in the central Northwest Territories, Arctic Canada. Mining operations took place within the claim area at the Tundra (1964-1968) and Salmita (1983-1987) mines. Giant Mine is located in the subarctic near the City of Yellowknife and mining at this site represents the longest continuous gold mining operation in Canada (1938 to 2002). Due to the refractory mineralogy of ore, gold was extracted from arsenopyrite by roasting, which resulted in release of substantial quantities of highly toxic arsenic trioxide to the environment. Arsenic (As) is also naturally elevated at these sites due its occurrence in Yellowknife Supergroup greenstone belts and surficial geologic deposits. To attempt to distinguish between geogenic and anthropogenic sources of As and characterize the role of climate change on metalloid mobility we used a freeze coring technology to capture lake sediments from the properties. Sediments were analyzed for sedimentary grain size and bulk geochemistry using ICP-MS to reconstruct climate and chemical change. Micropaleontological analyses are on-going. Interpretations of the physical, chemical, and biological archive
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
Soegaard, H.; Toudal, L.; Hansen, B. U.; Friborg, T.; Rennermalm, A.; Nordstroem, C.; Hinkler, J.
Since 1996 continuous measurements of CO2-exchange have been conducted at Zackenberg research station in the North-Eastern Greenland (74.5N, 20.5W) covering the growing season from the beginning of June to the end of August. Two different ecosystems have been monitored: wetland (1996-1999) and heath (1997, 2000-2002). For both systems a considerable interannual variability in carbon sequestration has been observed. For the wetland the average three month net ecosystem exchange (NEE) calculated on the basis of the above mentioned periods has been -53 g C m-2 covering a range from -96 to -30 g C m-2 , whereas for the heath site the corresponding figures are average = -10 g C m-2 and range from -19 to -3 g C m-2. The sensitivity of the NEE with respect to climate is evaluated by use of a combined photosynthesis/soil respiration model. For both ecosystems the density and duration of the snow cover is found to be a key parameter for interpreting the year-to-year variation. The denser the snow pack the more CO2 is released during the early melting season whereas a delayed snowmelt shortens the length of the growing season and thereby the summertime CO2 uptake. With respect to soil water balance the two systems responds differently; where the wetland suffer from waterlogged soil in most of the growing season, the CO2 uptake at the drier heat lands may be reduced due to water stress. Finally, the impact of large scale climatic fluctuations is discussed. This is done with focus on the variation in extension and duration of sea ice along the north-eastern coast of Greenland and the higher temperatures observed in the growing season 2002.
Wennrich, V.; Kukkonen, M.; Meyer-Jacob, C.; Minyuk, P.; Rosen, P.; Brigham-Grette, J.; Melles, M.; El'Gygytgyn Scientific Party
High arctic Lake El‘gygytgyn (67°30’ N, 172°05’ E) is a 3.6 Ma old meteorite crater lake located in Chukotka/NE Siberia, 100 km to the north of the Arctic Circle. With its continuous and undisturbed sequence since the Pliocene, the lake comprises the most long-lasting climate archive of the terrestrial Arctic. In spring 2009, the ICDP El‘gygytgyn Drilling Project recovered the 317-m long lacustrine sediment record from 170 m water depth at site D1 in the central lake part. Here we present initial results of elemental analyses as well as infrared spectroscopy of this record. The elemental composition of the lake sediment was investigated by a combination of high-resolution element analyses using an ITRAX X-ray Fluorescence (XRF) core scanner (Cox Analytics), and conventional XRF spectrometry. The results well reflect variations in sedimentation, weathering, lake hydrology and productivity mostly triggered by glacial-interglacial cycles. Furthermore, due to the high spatial resolution of the ITRAX even short-term fluctuations of those proxies could be detected, displaying the sensitivity of the Lake El‘gygytgyn sediments to regional and global climate changes on a decadal to centennial scale. Measurements of Fourier Transform Infrared Spectroscopy (FTIRS) in the mid-infrared (MIR) region were conducted to quantitatively estimate contents of biogenic silica (BSi), total nitrogen (TN), total organic carbon (TOC), and total inorganic carbon (TIC) in Lake El‘gygytgyn sediments. Simultaneous inference of these components is possible because IR-spectra in the MIR-region contain a wide variety of information on minerogenic and organic substances. The technique requires only small amounts (0.01g dry weight) of sample material and negligible sample pre-treatments. FTIRS calibrations for BSi, TN, TOC, and TIC based on core catcher samples of the sediment sequence yielded good statistical performances and emphasize the potential of the technique for high
Mayer, Michael; Haimberger, Leo
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.
Favaro, Elena A.; Lamoureux, Scott F.
Spatially and temporally variable suspended sediment transport from upstream sources was investigated in the West River (unofficial name) at the Cape Bounty Arctic Watershed Observatory (CBAWO) on Melville Island, Nunavut (74°55‧ N, 109°35‧ W), a river with nearly a decade of hydrological and sediment transport research in the Canadian Arctic and subject to recent permafrost disturbances, such as soil skin flows on slopes, massive ground ice melt in the channel, and substantial climate change. During the 2012 season, a survey was undertaken during the nival period to identify areas of the river where the flow was isolated from the channel bed by snow and where it progressively reached the bed. During the nival period, and throughout the rest of the season, suspended sediment transport data were collected from a primary outlet station and six upstream locations to identify the sources and sinks of sediment in the various reaches of the West River. An inferred sediment budget approach was used to identify the storage and release dynamics in each reach. Nival event-scale hysteresis and seasonal diurnal hysteresis patterns for 2012 were primarily anticlockwise, suggesting that sources of sediment were not readily available for transport during peak flows but became available as discharge waned. Analysis of diurnal hysteresis relationships for the years 2004-2012 (excluding 2011) signals a shift in daily sediment-discharge hysteresis from primarily clockwise to anticlockwise following an episode of permafrost disturbance and enhanced erosion in 2007. Consistent sediment storage in the upper catchment from this disturbance is interpreted to have contributed to the shift to anticlockwise daily hysteresis. Results provide insights into the fluvial and geomorphological response to changes in sediment availability in Arctic rivers and how these changes in turn affect sediment transport in these environments.
Klimešová, Jitka; Prach, Karel; Bernardová, Alexandra
We review the available data that can be used to assess the potential impact of climate change on vegetation, and we use central Spitsbergen, Svalbard, as a model location for the High Arctic. We used two sources of information: recent and short-term historical records, which enable assessment on scales of particular plant communities and the landscape over a period of decades, and palynological and macrofossil analyses, which enable assessment on time scales of hundreds and thousands of years and on the spatial scale of the landscape. Both of these substitutes for standardized monitoring revealed stability of vegetation, which is probably attributable to the harsh conditions and the distance of the area from sources of diaspores of potential new incomers. The only evident recent vegetation changes related to climate change are associated with succession after glacial retreats. By establishing a network of permanent plots, researchers will be able to monitor immigration of new species from diversity 'hot spots' and from an abandoned settlement nearby. This will greatly enhance our ability to understand the effects of climate change on vegetation in the High Arctic.
Cavalieri, D. J.; Haekkinen, S.; Zukor, Dorothy J. (Technical Monitor)
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.
Cavalieri, D. J.; Haekkinen, S.
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.
Høye, Toke Thomas; Hammel, Jörg U; Fuchs, Thomas; Toft, Søren
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.
Akperov, Mirseid; Mokhov, Igor; Rinke, Annette; Handorf, Doerthe; Dethloff, Klaus
The ability of the regional climate models (Arctic CORDEX) to simulate cyclone activity for the Arctic region is investigated. 10 regional climate models (RCMs), including models with and w/o "nudging" are considered. Comparing the characteristics of cyclone activity with the use of an ensemble of RCM's hindcast simulations and ERA-Interim reanalysis for four seasons (winter, spring, summer, autumn) and for last decades, biases in cyclone frequency, intensity and size over the Arctic (region ca. north of 60°N) are quantified. In spite of these biases RCM's are able to represent the characteristics of cyclone activity in the Arctic region, in particular RCM's with "nudging". The spread across the models are estimated. Additionally, the characteristics of extreme mesocyclones (polar lows) are investigated. The ability of RCM's and reanalyses (ERA-Interim, Arctic system reanalysis - ASR) to represent polar lows over the Barents and Kara Seas in comparison with satellite observations is assessed. Reanalyses and RCM's with high spatial resolution are able to represent ca. 50% of the observed polar lows.
Grachev, Andrey; Albee, Robert; Fairall, Christopher; Hare, Jeffrey; Persson, Ola; Uttal, Taneil
The Arctic region is experiencing unprecedented changes associated with increasing average temperatures (faster than the pace of the globally-averaged increase) and significant decreases in both the areal extent and thickness of the Arctic pack ice. These changes are early warning signs of shifts in the global climate system that justifies increased scientific focus on this region. The increase in atmospheric carbon dioxide has raised concerns worldwide about future climate change. Recent studies suggest that huge stores of carbon dioxide (and other climate relevant compounds) locked up in Arctic soils could be unexpectedly released due to global warming. Observational evidence suggests that atmospheric energy fluxes are a major contributor to the decrease of the Arctic pack ice, seasonal land snow cover and the warming of the surrounding land areas and permafrost layers. To better understand the atmosphere-surface exchange mechanisms, improve models, and to diagnose climate variability in the Arctic, accurate measurements are required of all components of the net surface energy budget and the carbon dioxide cycle over representative areas and over multiple years. In this study we analyze variability of turbulent fluxes including water vapor and carbon dioxide transfer based on long-term measurements made at Eureka observatory (80.0 N, 85.9 W) located near the coast of the Arctic Ocean (Canadian territory of Nunavut). Turbulent fluxes and mean meteorological data are continuously measured and reported hourly at various levels on a 10-m flux tower. Sonic anemometers are located at 3 and 8 m heights while high-speed Licor 7500 infrared gas analyzer (water moisture and carbon dioxide measurements) at 7.5 m height. According to our data, that the sensible heat flux, carbon dioxide and water vapor fluxes exhibited clear diurnal cycles in Arctic summer. This behavior is similar to the diurnal variation of the fluxes in mid-latitudes during the plants growing season, with
Welker, J.M.; Parsons, A.N.; Walker, M.D. |||
Field manipulations of environmental conditions have been established in dry tundra sites on Niwot Ridge, CO, Toolik Lake, AK and on Svalbard, Norway as part of the International Tundra Experiment (ITEX). Dryas octopetala is the dominant species at all three sites where we have examined organismic and ecosystem responses to similar increases in temperature. Leaf and seed mass differ significantly between all sites and warmer temperatures resulted in reductions in leaf mass at both the high and low arctic sites in the initial year, but this was not observed at the alpine site. Reductions in leaf mass were accompanied by changes in leaf demography. Seed masses were inherently different between sites, being largest from plants in the alpine tundra. Plants in the alpine and in the high arctic had higher seed weights when warmed. By the end of the second year, leaf C:N ratios were higher in alpine plants which were warmed. These organismic responses may set the stage for altered colonization of bare ground while changes in C:N ratios may modify decomposition rates linking organismic and ecosystem dynamics.
Surkova, Galina; Sokolova, Larisa
Extreme surface wind events over the Arctic (60-90N, 0-360 E) are studied for the modern climate and for its future possible changes on the base of ERA-Interim reanalysis data and CMIP5 scenario RCP8.5. Horizontal surface wind speed (10 m) probability distribution functions in every grid point of reanalysis and models data over the Arctic were evaluated as well as wind speed for 50, 95, 99, 99.9 percentiles (V0.50, V0.95, V0.99, V0.999). At first, changes of V0.50, V0.95, V0.99, V0.999 were studied on the base of ERA-Interim reanalysis for 1981-2010. Results showed regional inhomogenity of wind speed trend intensity. Also, analysis was made for zonal means and separate sectors of the Arctic. To study climate projection of high wind speed there were taken u,v values from CMIP5 numerical experiments for 1961-1990 (Historical) and 2081-2100 (RCP8.5). RCP8.5 scenario was chosen as having the most pronounced response in the climate system, which gave more statistical significance to the calculated trends. Modeled extreme wind speeds for the total Arctic and zonal means show rather good agreement with reanalysis data (compared for decades 1981-1990, 1991-2000). At the same time regional intermodel variability of wind speed is revealed. Trend of extreme surface wind speed in 21 century and for 2081-2100 over the Arctic are analyzed for each model. The study was supported by the Russian Science Foundation (project no. 14-37-00038).
Gogineni, Sivaprasad; Thomas, Robert H.; Abdalati, Waleed (Editor)
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.
Wang, X.; Key, J. R.; Liu, Y.
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
Shiklomanov, N. I.; Streletskiy, D. A.
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.
Wauchope, Hannah S; Shaw, Justine D; Varpe, Øystein; Lappo, Elena G; Boertmann, David; Lanctot, Richard B; Fuller, Richard A
Millions of birds migrate to and from the Arctic each year, but rapid climate change in the High North could strongly affect where species are able to breed, disrupting migratory connections globally. We modelled the climatically suitable breeding conditions of 24 Arctic specialist shorebirds and projected them to 2070 and to the mid-Holocene climatic optimum, the world's last major warming event ~6000 years ago. We show that climatically suitable breeding conditions could shift, contract and decline over the next 70 years, with 66-83% of species losing the majority of currently suitable area. This exceeds, in rate and magnitude, the impact of the mid-Holocene climatic optimum. Suitable climatic conditions are predicted to decline acutely in the most species rich region, Beringia (western Alaska and eastern Russia), and become concentrated in the Eurasian and Canadian Arctic islands. These predicted spatial shifts of breeding grounds could affect the species composition of the world's major flyways. Encouragingly, protected area coverage of current and future climatically suitable breeding conditions generally meets target levels; however, there is a lack of protected areas within the Canadian Arctic where resource exploitation is a growing threat. Given that already there are rapid declines of many populations of Arctic migratory birds, our results emphasize the urgency of mitigating climate change and protecting Arctic biodiversity.
Shiklomanov, Nikolay; Streletskiy, Dmitry; Swales, Timothy
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
Lee, Pascal; Boucher, M.; Desportes, C.; Glass, B. J.; Lim, D.; McKay, C. P.; Osinski, G. R.; Parnell, J.; Schutt, J. W.
Analysis of crater modification on Mars and at Haughton Crater, Devon Island, High Arctic, which was recently shown to be significantly older than previously believed (Eocene age instead of Miocene) , suggest that Mars may have never been climatically wet and warm for geological lengths of time during and since the Late Noachian. Impact structures offer particularly valuable records of the evolution of a planet s climate and landscape through time. The state of exposure and preservation of impact structures and their intracrater fill provide clues to the nature, timing, and intensity of the processes that have modified the craters since their formation. Modifying processes include weathering, erosion, mantling, and infilling. In this study, we compare the modification of Haughton through time with that of impact craters in the same size class on Mars. We derive upper limits for time-integrated denudation rates on Mars during and since the Late Noachian. These rates are significantly lower than previously published and provide important constraints for Mars climate evolution.
Bolsunovskaya, Y.; Volodina, D.; Sentsov, A.
The Arctic development is accompanied by different high risks which basically arise due to natural and technogenic factors. The changes in the Arctic cryosphere are commonly considered the most serious ones by the international scientific community. In our study we regard the changes in Arctic cryosphere as natural risks. Due to the fact that complex ice conditions, on the one hand, present the serious obstacle to Arctic resources development and, on the other hand, serve as indicator of alarming global climate change, the current research proposes the risk analysis based on the analytical model, with the risks being classified by their level of impact.
possibility that the climate system supports multiple Arctic sea ice states that are relevant for the evolution of sea ice during the next several...Use this model to identify quantities that indicate the stability of the system . (3) Examine these quantities in comprehensive climate model...simulations from the ONR ACNFS and other high-resolution models of the Arctic system . WORK COMPLETED During this first year, we completed Approach
Hof, Anouschka R; Jansson, Roland; Nilsson, Christer
Arctic and subarctic (i.e., [sub]arctic) ecosystems are predicted to be particularly susceptible to climate change. The area of tundra is expected to decrease and temperate climates will extend further north, affecting species inhabiting northern environments. Consequently, species at high latitudes should be especially susceptible to climate change, likely experiencing significant range contractions. Contrary to these expectations, our modelling of species distributions suggests that predicted climate change up to 2080 will favour most mammals presently inhabiting (sub)arctic Europe. Assuming full dispersal ability, most species will benefit from climate change, except for a few cold-climate specialists. However, most resident species will contract their ranges if they are not able to track their climatic niches, but no species is predicted to go extinct. If climate would change far beyond current predictions, however, species might disappear. The reason for the relative stability of mammalian presence might be that arctic regions have experienced large climatic shifts in the past, filtering out sensitive and range-restricted taxa. We also provide evidence that for most (sub)arctic mammals it is not climate change per se that will threaten them, but possible constraints on their dispersal ability and changes in community composition. Such impacts of future changes in species communities should receive more attention in literature.
Gilg, Olivier; Kovacs, Kit M; Aars, Jon; Fort, Jérôme; Gauthier, Gilles; Grémillet, David; Ims, Rolf A; Meltofte, Hans; Moreau, Jérôme; Post, Eric; Schmidt, Niels Martin; Yannic, Glenn; Bollache, Loïc
Climate change is taking place more rapidly and severely in the Arctic than anywhere on the globe, exposing Arctic vertebrates to a host of impacts. Changes in the cryosphere dominate the physical changes that already affect these animals, but increasing air temperatures, changes in precipitation, and ocean acidification will also affect Arctic ecosystems in the future. Adaptation via natural selection is problematic in such a rapidly changing environment. Adjustment via phenotypic plasticity is therefore likely to dominate Arctic vertebrate responses in the short term, and many such adjustments have already been documented. Changes in phenology and range will occur for most species but will only partly mitigate climate change impacts, which are particularly difficult to forecast due to the many interactions within and between trophic levels. Even though Arctic species richness is increasing via immigration from the South, many Arctic vertebrates are expected to become increasingly threatened during this century.
Moritz, Richard E; Bitz, Cecilia M; Steig, Eric J
The pattern of recent surface warming observed in the Arctic exhibits both polar amplification and a strong relation with trends in the Arctic Oscillation mode of atmospheric circulation. Paleoclimate analyses indicate that Arctic surface temperatures were higher during the 20th century than during the preceding few centuries and that polar amplification is a common feature of the past. Paleoclimate evidence for Holocene variations in the Arctic Oscillation is mixed. Current understanding of physical mechanisms controlling atmospheric dynamics suggests that anthropogenic influences could have forced the recent trend in the Arctic Oscillation, but simulations with global climate models do not agree. In most simulations, the trend in the Arctic Oscillation is much weaker than observed. In addition, the simulated warming tends to be largest in autumn over the Arctic Ocean, whereas observed warming appears to be largest in winter and spring over the continents.
Revich, Boris; Tokarevich, Nikolai; Parkinson, Alan J
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.
Fuglestvedt, Jan S; Dalsøren, Stig Bjørløw; Samset, Bjørn Hallvard; Berntsen, Terje; Myhre, Gunnar; Hodnebrog, Øivind; Eide, Magnus Strandmyr; Bergh, Trond Flisnes
The changing climate in the Arctic opens new shipping routes. A shift to shorter Arctic transit will, however, incur a climate penalty over the first one and a half centuries. We investigate the net climate effect of diverting a segment of Europe-Asia container traffic from the Suez to an Arctic transit route. We find an initial net warming for the first one-and-a-half centuries, which gradually declines and transitions to net cooling as the effects of CO2 reductions become dominant, resulting in climate mitigation only in the long term. Thus, the possibilities for shifting shipping to the Arctic confront policymakers with the question of how to weigh a century-scale warming with large uncertainties versus a long-term climate benefit from CO2 reductions.
Martello, Marybeth Long
Recent scientific findings, as presented in the Arctic Climate Impact Assessment (ACIA), indicate that climate change in the Arctic is happening now, at a faster rate than elsewhere in the world, and with major implications for peoples of the Arctic (especially indigenous peoples) and the rest of the planet. This paper examines scientific and political representations of Arctic indigenous peoples that have been central to the production and articulation of these claims. ACIA employs novel forms and strategies of representation that reflect changing conceptual models and practices of global change science and depict indigenous peoples as expert, exotic, and at-risk. These portrayals emerge alongside the growing political activism of Arctic indigenous peoples who present themselves as representatives or embodiments of climate change itself as they advocate for climate change mitigation policies. These mutually constitutive forms of representation suggest that scientific ways of seeing the global environment shape and are shaped by the public image and voice of global citizens. Likewise, the authority, credibility, and visibility of Arctic indigenous activists derive, in part, from their status as at-risk experts, a status buttressed by new scientific frameworks and methods that recognize and rely on the local experiences and knowledges of indigenous peoples. Analyses of these relationships linking scientific and political representations of Arctic climate change build upon science and technology studies (STS) scholarship on visualization, challenge conventional notions of globalization, and raise questions about power and accountability in global climate change research.
Bertram, Kathryn Berry
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…
Morin, Paul; Porter, Claire; Cloutier, Michael; Howat, Ian; Noh, Myoung-Jong; Willis, Michael; Bates, Brian; Willamson, Cathleen; Peterman, Kennith
A Digital Elevation Model (DEM) of the Arctic is needed for a large number of reasons, including: measuring and understanding rapid, ongoing changes to the Arctic landscape resulting from climate change and human use and mitigation and adaptation planning for Arctic communities. The topography of the Arctic is more poorly mapped than most other regions of Earth due to logistical costs and the limits of satellite missions with low-latitude inclinations. A convergence of civilian, high-quality sub-meter stereo imagery; petascale computing and open source photogrammetry software has made it possible to produce a complete, very high resolution (2 to 8-meter posting), elevation model of the Arctic. A partnership between the US National Geospatial-intelligence Agency and a team led by the US National Science Foundation funded Polar Geospatial Center is using stereo imagery from DigitalGlobe's Worldview-1, 2 and 3 satellites and the Ohio State University's Surface Extraction with TIN-based Search-space Minimization (SETSM) software running on the University of Illinois's Blue Water supercomputer to address this challenge. The final product will be a seemless, 2-m posting digital surface model mosaic of the entire Arctic above 60 North including all of Alaska, Greenland and Kamchatka. We will also make available the more than 300,000 individual time-stamped DSM strip pairs that were used to assemble the mosaic. The Arctic DEM will have a vertical precision of better than 0.5m and can be used to examine changes in land surfaces such as those caused by permafrost degradation or the evolution of arctic rivers and floodplains. The data set can also be used to highlight changing geomorphology due to Earth surface mass transport processes occurring in active volcanic and glacial environments. When complete the ArcticDEM will catapult the Arctic from the worst to among the best mapped regions on Earth.
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
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.
Wennrich, V.; Minyuk, P. S.; Borkhodoev, V.; Francke, A.; Ritter, B.; Nowaczyk, N. R.; Sauerbrey, M. A.; Brigham-Grette, J.; Melles, M.
The 3.6 Ma sediment record of Lake El'gygytgyn/NE Russia, Far East Russian Arctic, represents the longest continuous climate archive of the terrestrial Arctic. Its elemental composition as determined by X-ray fluorescence scanning exhibits significant changes since the mid-Pliocene caused by climate-driven variations in primary production, postdepositional diagenetic processes, and lake circulation as well as weathering processes in its catchment. During the mid- to late Pliocene, warmer and wetter climatic conditions are reflected by elevated Si / Ti ratios, indicating enhanced diatom production in the lake. Prior to 3.3 Ma, this signal is overprinted by intensified detrital input from the catchment, visible in maxima of clastic-related proxies, such as K. In addition, calcite formation in the early lake history points to enhanced Ca flux into the lake caused by intensified weathering in the catchment. A lack of calcite deposition after ca. 3.3 Ma is linked to the development of permafrost in the region triggered by cooling in the mid-Pliocene. After ca. 3.0 Ma the elemental data suggest a gradual transition to Pleistocene-style glacial-interglacial cyclicity. In the early Pleistocene, the cyclicity was first dominated by variations on the 41 kyr obliquity band but experienced a change to a 100 kyr eccentricity dominance during the middle Pleistocene transition (MPT) at ca. 1.2-0.6 Ma. This clearly demonstrates the sensitivity of the Lake El'gygytgyn record to orbital forcing. A successive decrease of the baseline levels of the redox-sensitive Mn / Fe ratio and magnetic susceptibility between 2.3 and 1.8 Ma reflects an overall change in the bottom-water oxygenation due to an intensified occurrence of pervasive glacial episodes in the early Pleistocene. The coincidence with major changes in the North Pacific and Bering Sea paleoceanography at ca. 1.8 Ma implies that the change in lake hydrology was caused by a regional cooling in the North Pacific and the western
Whitmore, J.; Gajewski, K.
Ice cores have provided key records of the late-Quaternary climates of the North American Arctic. However, these are spatially restricted and are available only in the glaciated eastern Arctic and Greenland. Ten pollen diagrams are available from Banks, Prince of Wales, Somerset, Ellesmere and Baffin Island describe the changes in the postglacial vegetation. These pollen assemblages, along with other proxy-climate data, have been interpreted as indicating a relatively warm early Holocene with a cooling in the past several 1000 years. However, quantitative reconstructions of the magnitude of temperature change have been hampered by lack of a sufficiently extensive modern calibration dataset. A new modern pollen dataset has recently been prepared, permitting the quantitative reconstructions of summer conditions across the Arctic. We use the modern pollen dataset, along with high-resolution estimates of July temperatures to estimate the magnitude of the Holocene climate changes across the Arctic and compare these results to the ice core records.
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
Loranty, Michael M.; Goetz, Scott J.
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
Weckström, J.; Korhola, A.; Väliranta, M.; Seppä, H.; Luoto, M.; Tuittila, E.-S.; Leppäranta, M.; Kahilainen, K.; Saarinen, J.; Heikkinen, H.
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
Chetelat, J.; Richardson, M.; MacMillan, G. A.; Amyot, M.; Hintelmann, H.; Crump, D.
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
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.
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
Nakamura, Tetsu; Yamazaki, Koji; Iwamoto, Katsushi; Honda, Meiji; Miyoshi, Yasunobu; Ogawa, Yasunobu; Tomikawa, Yoshihiro; Ukita, Jinro
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.
Makar, Jennifer Andrea
Both the observed and predicted ecological effects of climate change are threatening the environmental systems that support life on Earth. Currently, black carbon (BC) is contributing more to global warming than previously thought, and is second only to carbon dioxide in its contribution to the changing climate. Black carbon affects Arctic climate through multiple mechanisms that should be examined such as radiation, cloud reflectivity and stability. Through regression analysis, this study suggests that black carbon explains approximately 30% of the variation in Arctic temperature by interfering with solar radiation which causes dimming and cooling at the surface.
Elements of Earth's cryosphere, such as the summer Arctic sea ice pack, are melting at precipitous rates that have far outpaced the projections of large scale climate models. Understanding key processes, such as the evolution of melt ponds that form atop Arctic sea ice and control its optical properties, is crucial to improving climate projections. These types of critical phenomena in the cryosphere are of increasing interest as the climate system warms, and are crucial for predicting its stability. In this paper, we consider how geometrical properties of melt ponds can influence ice-albedo feedback and how it can influence the equilibria in the energy balance of the planet.
Ionita-Scholz, Monica; Grosfeld, Klaus; Lohmann, Gerrit; Scholz, Patrick
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
Greenwood, D. R.; West, C. K.; Basinger, J. F.
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
Dudley, Joseph P; Hoberg, Eric P; Jenkins, Emily J; Parkinson, Alan J
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.
Briner, Jason P.; McKay, Nicholas P.; Axford, Yarrow; Bennike, Ole; Bradley, Raymond S.; de Vernal, Anne; Fisher, David; Francus, Pierre; Fréchette, Bianca; Gajewski, Konrad; Jennings, Anne; Kaufman, Darrell S.; Miller, Gifford; Rouston, Cody; Wagner, Bernd
This synthesis paper summarizes published proxy climate evidence showing the spatial and temporal pattern of climate change through the Holocene in Arctic Canada and Greenland. Our synthesis includes 47 records from a recently published database of highly resolved Holocene paleoclimate time series from the Arctic (Sundqvist et al., 2014). We analyze the temperature histories represented by the database and compare them with paleoclimate and environmental information from 54 additional published records, mostly from datasets that did not fit the selection criteria for the Arctic Holocene database. Combined, we review evidence from a variety of proxy archives including glaciers (ice cores and glacial geomorphology), lake sediments, peat sequences, and coastal and deep-marine sediments. 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 sites). 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.
Eichelberger, J. C.; Eichelberger, L. P.
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
Andrews, J.T.; Short, S.K.
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.
Cvijanovic, Ivana; Caldeira, Ken; MacMartin, Douglas G.
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
Cvijanovic, Ivana; Caldeira, Ken; MacMartin, Douglas G.
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.
Burt, Melissa Ann
The Arctic climate system involves complex interactions among the atmosphere, land surface, and the sea-ice-covered Arctic Ocean. Observed changes in the Arctic have emerged and projected climate trends are of significant concern. Surface warming over the last few decades is nearly double that of the entire Earth. Reduced sea-ice extent and volume, changes to ecosystems, and melting permafrost are some examples of noticeable changes in the region. This work is aimed at improving our understanding of how Arctic clouds interact with, and influence, the surface budget, how clouds influence the distribution of sea ice, and the role of downwelling longwave radiation (DLR) in climate change. In the first half of this study, we explore the roles of sea-ice thickness and downwelling longwave radiation in Arctic amplification. As the Arctic sea ice thins and ultimately disappears in a warming climate, its insulating power decreases. This causes the surface air temperature to approach the temperature of the relatively warm ocean water below the ice. The resulting increases in air temperature, water vapor and cloudiness lead to an increase in the surface downwelling longwave radiation, which enables a further thinning of the ice. This positive ice-insulation feedback operates mainly in the autumn and winter. A climate-change simulation with the Community Earth System Model shows that, averaged over the year, the increase in Arctic DLR is three times stronger than the increase in Arctic absorbed solar radiation at the surface. The warming of the surface air over the Arctic Ocean during fall and winter creates a strong thermal contrast with the colder surrounding continents. Sea-level pressure falls over the Arctic Ocean and the high-latitude circulation reorganizes into a shallow "winter monsoon." The resulting increase in surface wind speed promotes stronger surface evaporation and higher humidity over portions of the Arctic Ocean, thus reinforcing the ice-insulation feedback
Qian, Weihong; Wu, Kaijun; Leung, Jeremy Cheuk-Hin
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.
Overland, James E.; Wang, Muyin; Walsh, John E.; Stroeve, Julienne C.
The climate in the Arctic is changing faster than in midlatitudes. This is shown by increased temperatures, loss of summer sea ice, earlier snow melt, impacts on ecosystems, and increased economic access. Arctic sea ice volume has decreased by 75% since the 1980s. Long-lasting global anthropogenic forcing from carbon dioxide has increased over the previous decades and is anticipated to increase over the next decades. Temperature increases in response to greenhouse gases are amplified in the Arctic through feedback processes associated with shifts in albedo, ocean and land heat storage, and near-surface longwave radiation fluxes. Thus, for the next few decades out to 2040, continuing environmental changes in the Arctic are very likely, and the appropriate response is to plan for adaptation to these changes. For example, it is very likely that the Arctic Ocean will become seasonally nearly sea ice free before 2050 and possibly within a decade or two, which in turn will further increase Arctic temperatures, economic access, and ecological shifts. Mitigation becomes an important option to reduce potential Arctic impacts in the second half of the 21st century. Using the most recent set of climate model projections (CMIP5), multimodel mean temperature projections show an Arctic-wide end of century increase of +13°C in late fall and +5°C in late spring for a business-as-usual emission scenario (RCP8.5) in contrast to +7°C in late fall and +3°C in late spring if civilization follows a mitigation scenario (RCP4.5). Such temperature increases demonstrate the heightened sensitivity of the Arctic to greenhouse gas forcing.
Kholmyansky, Mikhael; Anokhin, Vladimir; Kartashov, Alexandr
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
Schultz, T.; MacCracken, M. C.
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
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.
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.
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.
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
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
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.
Bowden, Joseph J.; Eskildsen, Anne; Hansen, Rikke R.; Olsen, Kent; Kurle, Carolyn M.; Høye, Toke T.
The response of body size to increasing temperature constitutes a universal response to climate change that could strongly affect terrestrial ectotherms, but the magnitude and direction of such responses remain unknown in most species. The metabolic cost of increased temperature could reduce body size but long growing seasons could also increase body size as was recently shown in an Arctic spider species. Here, we present the longest known time series on body size variation in two High-Arctic butterfly species: Boloria chariclea and Colias hecla. We measured wing length of nearly 4500 individuals collected annually between 1996 and 2013 from Zackenberg, Greenland and found that wing length significantly decreased at a similar rate in both species in response to warmer summers. Body size is strongly related to dispersal capacity and fecundity and our results suggest that these Arctic species could face severe challenges in response to ongoing rapid climate change. PMID:26445981
Bowden, Joseph J; Eskildsen, Anne; Hansen, Rikke R; Olsen, Kent; Kurle, Carolyn M; Høye, Toke T
The response of body size to increasing temperature constitutes a universal response to climate change that could strongly affect terrestrial ectotherms, but the magnitude and direction of such responses remain unknown in most species. The metabolic cost of increased temperature could reduce body size but long growing seasons could also increase body size as was recently shown in an Arctic spider species. Here, we present the longest known time series on body size variation in two High-Arctic butterfly species: Boloria chariclea and Colias hecla. We measured wing length of nearly 4500 individuals collected annually between 1996 and 2013 from Zackenberg, Greenland and found that wing length significantly decreased at a similar rate in both species in response to warmer summers. Body size is strongly related to dispersal capacity and fecundity and our results suggest that these Arctic species could face severe challenges in response to ongoing rapid climate change.
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.
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
Zhang, Wenxin; Jansson, Christer; Miller, Paul; Smith, Ben; Samuelsson, Patrick
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
Stien, Audun; Ims, Rolf A; Albon, Steve D; Fuglei, Eva; Irvine, R Justin; Ropstad, Erik; Halvorsen, Odd; Langvatn, Rolf; Loe, Leif Egil; Veiberg, Vebjørn; Yoccoz, Nigel G
Assessing the role of weather in the dynamics of wildlife populations is a pressing task in the face of rapid environmental change. Rodents and ruminants are abundant herbivore species in most Arctic ecosystems, many of which are experiencing particularly rapid climate change. Their different life-history characteristics, with the exception of their trophic position, suggest that they should show different responses to environmental variation. Here we show that the only mammalian herbivores on the Arctic islands of Svalbard, reindeer (Rangifer tarandus) and sibling voles (Microtus levis), exhibit strong synchrony in population parameters. This synchrony is due to rain-on-snow events that cause ground ice and demonstrates that climate impacts can be similarly integrated and expressed in species with highly contrasting life histories. The finding suggests that responses of wildlife populations to climate variability and change might be more consistent in Polar regions than elsewhere owing to the strength of the climate impact and the simplicity of the ecosystem.
Alekseev, G. V.; Aleksandrov, E. I.; Glok, N. I.; Ivanov, N. E.; Smolyanitsky, V. M.; Kharlanenkova, N. E.; Yulin, A. V.
Recently published studies on key issues in the evolution of Arctic sea ice cover are reviewed and attempts to answer disputable questions are made in the research part of the work. It is shown that climate warming, manifested in an increase in the surface air temperature, and reduction in the ice cover develop with a high degree of agreement in summer. Based on this fact, anomalies of the September ice-cover area have been retrieved from 1900. They show a significant decrease in the 1930-1940s, which is almost twice as low as in 2007-2012. The influence of fluctuations in the flow of warm and salty Atlantic water is noted in variations in the winter maximum of the ice-cover area in the Barents Sea. An accelerated positive trend has been ascertained for the air temperature in late autumn-early winter in 1993-2012 due to an increase in the open water area in late summer. Inherent regularities of the ice-cover-area variability made it possible to develop a prediction of the monthly values of sea-ice extent with a head time from 6 months to 2 years. Their strong correlation with summer air temperature is used to estimate the onset of summer ice clearance in the Arctic.
Soreide, N. N.; Overland, J. E.; Calder, J. A.; Rodionov, S.
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
McFarlane Tranquilla, Laura; Hedd, April; Burke, Chantelle; Montevecchi, William A.; Regular, Paul M.; Robertson, Gregory J.; Stapleton, Leslie Ann; Wilhelm, Sabina I.; Fifield, David A.; Buren, Alejandro D.
Ocean climate change is having profound biological effects in polar regions. Such change can also have far-reaching downstream effects in sub-polar regions. This study documents an environmental relationship between High Arctic sea ice changes and mortality events of marine birds in Low Arctic coastal regions. During April 2007 and March 2009, hundreds of beached seabird carcasses and moribund seabirds were found along the east and northeast coasts of Newfoundland, Canada. These seabird "wrecks" (i.e. dead birds on beaches) coincided with a period of strong, persistent onshore winds and heavily-accumulated sea ice that blocked bays and trapped seabirds near beaches. Ninety-two percent of wreck seabirds were Thick-billed Murres ( Uria lomvia). Body condition and demographic patterns of wreck murres were compared to Thick-billed Murres shot in the Newfoundland murre hunt. Average body and pectoral masses of wreck carcasses were 34% and 40% lighter (respectively) than shot murres, indicating that wreck birds had starved. The acute nature of each wreck suggested that starvation and associated hypothermia occurred within 2-3 days. In 2007, first-winter murres (77%) dominated the wreck. In 2009, there were more adults (78%), mostly females (66%). These results suggest that spatial and temporal segregation in ages and sexes can play a role in differential survival when stochastic weather conditions affect discrete areas where these groups aggregate. In wreck years, southward movement of Arctic sea ice to Low Arctic latitudes was later and blocked bays longer than in most other years. These inshore conditions corresponded with recent climate-driven changes in High Arctic ice break-up and ice extent; coupled with local weather conditions, these ice conditions appeared to be the key environmental features that precipitated the ice-associated seabird wrecks in the Low Arctic region.
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.
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.
McGinnis, D.L.; Crane, R.G. )
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.
Shupe, M.; Persson, O. P.; Tjernstrom, M. K.; Dethloff, K.
Arctic become more biologically productive and what are the consequences of this to other components of the system? *How do the different scales of heterogeneity within the atmosphere ice and ocean interact to impact the linkages or feedbacks within the system? *How do interfacial exchange rates, biology and chemistry couple to regulate the major elemental cycles? MOSAiC will address these multi-disciplinary questions using intensive observations and modeling of processes that transfer energy, mass, and momentum through the atmosphere-ice-ocean system. The centerpiece of the observatory will be an icebreaker-based station to serve as a hub for intensive and comprehensive observations of climatically-significant physical, chemical, and biological processes through the vertical column. To provide important spatial context and horizontal variability, this facility will be the focal point for a constellation of coordinated observations made by drifting buoys, unmanned aerial and underwater vehicles, aircraft, ships, and satellites. These MOSAiC observational activities will serve as a testbed for evaluation and development of models at scales ranging from high-resolution, process models to regional and global climate models. MOSAiC observational and modeling activities will be linked at the outset, such that model needs will be integral in observational design, implementation, and analysis.
Wardell, Lois; Chen, Linling; Strey, Sara
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.
Mienert, Jurgen; Andreassen, Karin; Bünz, Stefan; Carroll, JoLynn; Ferre, Benedicte; Knies, Jochen; Panieri, Giuliana; Rasmussen, Tine; Myhre, Cathrine Lund
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
McKuin, Brandi; Campbell, J. Elliott
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.
Mengis, N.; Martin, T.; Keller, D. P.; Oschlies, A.
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.
Stephenson, Scott R.; Smith, Laurence C.
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.
Kortsch, Susanne; Primicerio, Raul; Beuchel, Frank; Renaud, Paul E.; Rodrigues, João; Lønne, Ole Jørgen; Gulliksen, Bjørn
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
Kortsch, Susanne; Primicerio, Raul; Beuchel, Frank; Renaud, Paul E; Rodrigues, João; Lønne, Ole Jørgen; Gulliksen, Bjørn
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.
Taylor, Mark A.; Zak, Bernard Daniel; Backus, George A.; Ivey, Mark D.; Boslough, Mark Bruce Elrick
organizations. Because changes in the Arctic environment are happening so rapidly, a successful program will be one that can adapt very quickly to new information as it becomes available, and can provide decision makers with projections on the 1-5 year time scale over which the most disruptive, high-consequence changes are likely to occur. The greatest short-term impact would be to initiate exploratory simulations to discover new emergent and robust phenomena associated with one or more of the following changing systems: Arctic hydrological cycle, sea ice extent, ocean and atmospheric circulation, permafrost deterioration, carbon mobilization, Greenland ice sheet stability, and coastal erosion. Sandia can also contribute to new technology solutions for improved observations in the Arctic, which is currently a data-sparse region. Sensitivity analyses have the potential to identify thresholds which would enable the collaborative development of 'early warning' sensor systems to seek predicted phenomena that might be precursory to major, high-consequence changes. Much of this work will require improved regional climate models and advanced computing capabilities. Socio-economic modeling tools can help define human and national security consequences. Formal uncertainty quantification must be an integral part of any results that emerge from this work.
Carton, James A.; Ding, Yanni; Arrigo, Kevin R.
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.
Geissler, W. H.; Knies, J.; Nielsen, T.; Gaina, C.; Matthiessen, J. J.; Gebhardt, C.; Damm, V.; Forwick, M.; Hjelstuen, B. O.; Hopper, J. R.; Husum, K.; Laberg, J. S.; Kuerschner, W.; Morigi, C.; Schreck, M.; Tripati, A. K.; Vogt, C. M.; Rebesco, M.; Nam, S. I.; Carlson, A. E.; De Schepper, S.; Lucchi, R.; Mattingsdal, R.; Jokat, W.; Stein, R. H.
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 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: • 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 • 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.
Jueterbock, Alexander; Smolina, Irina; Coyer, James A; Hoarau, Galice
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.
Ackerman, D.; Finlay, J. C.; Griffin, D.
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.
Rybczynski, N.; Ballantyne, A.; Csank, A.; Matheus, P.
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.
Livensperger, C.; Steltzer, H.; Wallenstein, M. D.; Weintraub, M. N.
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.
Wiedermann, M.; Donges, J. F.; Heitzig, J.; Kurths, J.
from complex network theory yielding "node splitting invariant (n.s.i.) network measures". The proposed weighted n.s.i. cross-network measures are readily applicable to general geoscientific problems involving networks with differently sized nodes and a given partition into subnetworks or communities. Our application consists of two parts: In the first part we perform a coupled climate network analysis in order to investigate the interaction between the SST and the SLP field that highlights two regions, one in the Atlantic and one in the Pacific, where SLP shows high coupling with SST. Starting from this we perform a more detailed analysis of coupled climate networks consisting of the SST field and isobaric layers of GPH at different altitudes, respectively. Our results show a strong coupling of the 200 mbar height level of GPH with the sea surface temperature by means of the n.s.i.-cross degree. Furthermore the n.s.i.-cross betweenness centrality points out interesting structures in the vertical direction. These results give first hints at the complex interplay between oceanic and atmospheric processes involved in Arctic climate dynamics.
Roberts, A.; Maslowski, W.; Osinski, R.; Cassano, J. J.; Craig, A.; Duvivier, A.; Fisel, B. J.; Gutowski, W. J.; Higgins, M.; Hughes, M. R.; Lettenmaier, D. P.; Nijssen, B.
The Regional Arctic System Model (RASM) is a high-resolution Earth System model extending across the Arctic Ocean, its marginal seas, the Arctic drainage basin, and including the Coordinated Regional Downscaling Experiment (CORDEX) Arctic domain. RASM uses the flux coupler (CPL7) within the Community Earth System Model framework to couple regional configurations of the Weather Research and Forecasting model (WRF), Parallel Ocean Program (POP), Los Alamos sea ice model (CICE), and Variable Infiltration Capacity land hydrology model (VIC). Work is also underway to incorporate the Community Ice Sheet Model (CISM) as well as glacier, ice cap and dynamic vegetation models. As part of RASM development, coupled simulations are being prepared for the CORDEX Arctic domain, which is unique among CORDEX regions by being centered over the ocean. Up to this point, there has been uncertainty over how much initial and surface conditions in the ice-ocean boundary layer influence the surface climate of the Arctic in RASM, relative to regional atmospheric model constraints, such as spectral nudging and boundary conditions. We present results that suggest there is a significant dependency on the initial sea ice conditions on decadal timescales within RASM. This has important implications for (i) how results from different regional artic models may be combined and compared in CORDEX and (ii) appropriate methods for ensemble generation in regional polar models. We will also present results illustrating the influence of sub-hourly sea ice deformation on decadal climate in RASM, highlighting an important reason why fully coupled and high-resolution regional models are essential for regional Arctic downscaling.
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.
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
Arnold, S.; Monks, S. A.; Emmons, L. K.; Sitch, S.; Rap, A.; Law, K.; Tilmes, S.; Lamarque, J.
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
Ragen, Timothy J; Huntington, Henry P; Hovelsrud, Grete K
On a daily basis, societies are making decisions that will influence the effects of climate change for decades or even centuries to come. To promote informed management of the associated risks, we review available conservation measures for Arctic marine mammals, a group that includes some of the most charismatic species on earth. The majority of available conservation measures (e.g., restrictions on hunting, protection of essential habitat areas from development, reduction of incidental take) are intended to address the effects of increasing human activity in the Arctic that are likely to follow decreasing sea ice and rising temperatures. As important as those measures will be in the effort to conserve Arctic marine mammals and ecosystems, they will not address the primary physical manifestations of climate change, such as loss of sea ice. Short of actions to prevent climate change, there are no known conservation measures that can be used to ensure the long-term persistence of these species and ecosystems as we know them today.
Ford, James D.; McDowell, Graham; Jones, Julie
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.
Callaghan, Terry V; Björn, Lars Olof; Chernov, Yuri; Chapin, Terry; Christensen, Torben R; Huntley, Brian; Ims, Rolf A; Johansson, Margareta; Jolly, Dyanna; Jonasson, Sven; Matveyeva, Nadya; Panikov, Nicolai; Oechel, Walter; Shaver, Gus
At the last glacial maximum, vast ice sheets covered many continental areas. The beds of some shallow seas were exposed thereby connecting previously separated landmasses. Although some areas were ice-free and supported a flora and fauna, mean annual temperatures were 10-13 degrees C colder than during the Holocene. Within a few millennia of the glacial maximum, deglaciation started, characterized by a series of climatic fluctuations between about 18,000 and 11,400 years ago. Following the general thermal maximum in the Holocene, there has been a modest overall cooling trend, superimposed upon which have been a series of millennial and centennial fluctuations in climate such as the "Little Ice Age spanning approximately the late 13th to early 19th centuries. Throughout the climatic fluctuations of the last 150,000 years, Arctic ecosystems and biota have been close to their minimum extent within the most recent 10,000 years. They suffered loss of diversity as a result of extinctions during the most recent large-magnitude rapid global warming at the end of the last glacial stage. Consequently, Arctic ecosystems and biota such as large vertebrates are already under pressure and are particularly vulnerable to current and projected future global warming. Evidence from the past indicates that the treeline will very probably advance, perhaps rapidly, into tundra areas, as it did during the early Holocene, reducing the extent of tundra and increasing the risk of species extinction. Species will very probably extend their ranges northwards, displacing Arctic species as in the past. However, unlike the early Holocene, when lower relative sea level allowed a belt of tundra to persist around at least some parts of the Arctic basin when treelines advanced to the present coast, sea level is very likely to rise in future, further restricting the area of tundra and other treeless Arctic ecosystems. The negative response of current Arctic ecosystems to global climatic conditions
Maldonado, Maria Teresa; Li, Jingxuan; Semeniuk, David; Schuback, Nina; Hoppe, Clara; AWI/UBC Collaboration
Phytoplankton, unicellular algae, are responsible for 50% of earth's photosynthesis, and for a significant consumption of atmospheric CO2. Iron (Fe) is essential for phytoplankton, but is extremely depleted in seawater, limiting photosynthesis in 30% of the global ocean. Oceanic Fe bioavailability is determined by physical and chemical processes. The Arctic Ocean is experiencing the greatest decrease in seawater pH (termed ocean acidification). Simultaneously, ice retreat is promoting higher light intensity in Arctic Ocean. We investigated the effects of ocean acidification and high light on Fe availability to Arctic phytoplankton. Iron uptake rates by plankton, using the radionuclide 55Fe, were used as a proxy for Fe bioavailability. In an Arctic summer research cruise, we measured Fe uptake by two phytoplankton populations subjected to two light levels, as well as present CO2 levels (400ppm) or those expected by 2100 (1100 ppm). Our results demonstrated that high CO2 decreases Fe availability, while high light increases it, suggesting that future Fe bioavailability might be similar to present day. However, the detrimental effects of high CO2 were more pronounced in the plankton population exposed to higher seawater temperature. Future studies should investigate the interaction among light, CO2 and temperature on the Fe physiology of Arctic phytoplankton.
Burek, Kathy A; Gulland, Frances M D; O'Hara, Todd M
The lack of integrated long-term data on health, diseases, and toxicant effects in Arctic marine mammals severely limits our ability to predict the effects of climate change on marine mammal health. The overall health of an individual animal is the result of complex interactions among immune status, body condition, pathogens and their pathogenicity, toxicant exposure, and the various environmental conditions that interact with these factors. Climate change could affect these interactions in several ways. There may be direct effects of loss of the sea ice habitat, elevations of water and air temperature, and increased occurrence of severe weather. Some of the indirect effects of climate change on animal health will likely include alterations in pathogen transmission due to a variety of factors, effects on body condition due to shifts in the prey base/food web, changes in toxicant exposures, and factors associated with increased human habitation in the Arctic (e.g., chemical and pathogen pollution in the runoff due to human and domestic-animal wastes and chemicals and increased ship traffic with the attendant increased risks of ship strike, oil spills, ballast pollution, and possibly acoustic injury). The extent to which climate change will impact marine mammal health will also vary among species, with some species more sensitive to these factors than others. Baseline data on marine mammal health parameters along with matched data on the population and climate change trends are needed to document these changes.
Hamilton, Lawrence C; Saito, Kei; Loring, Philip A; Lammers, Richard B; Huntington, Henry P
Residents of towns and villages in Arctic Alaska live on "the front line of climate change." Some communities face immediate threats from erosion and flooding associated with thawing permafrost, increasing river flows, and reduced sea ice protection of shorelines. The term climigration, referring to migration caused by climate change, originally was coined for these places. Although initial applications emphasized the need for government relocation policies, it has elsewhere been applied more broadly to encompass unplanned migration as well. Some historical movements have been attributed to climate change, but closer study tends to find multiple causes, making it difficult to quantify the climate contribution. Clearer attribution might come from comparisons of migration rates among places that are similar in most respects, apart from known climatic impacts. We apply this approach using annual 1990-2014 time series on 43 Arctic Alaska towns and villages. Within-community time plots show no indication of enhanced out-migration from the most at-risk communities. More formally, there is no significant difference between net migration rates of at-risk and other places, testing several alternative classifications. Although climigration is not detectable to date, growing risks make either planned or unplanned movements unavoidable in the near future.
Stauffer, Barbara W.
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.
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
Hurwitz, M. M.; Newman, P. A.; Garfinkel, C. I.
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 strengthened 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 spring, affecting the April clear-sky UV index at Northern Hemisphere midlatitudes.
Sewall, J. O.; Sloan, L. C.
Paleoclimate researchers recognize the Early Paleogene as a particularly warm interval in Earth's history. Paleogene proxy climate indicators suggest warm polar and mid-latitude continental interior temperatures, and a reduced latitudinal temperature gradient. Most researchers believe that Early Paleogene climate was driven by forcing fields that act globally (e.g. greenhouse gases). However, modeling work based on the influence of global forcing fields has failed to reproduce the warm Paleogene climate indicated by proxy data. Quite possibly, an ameliorating influence acting directly at the poles, rather than over the entire globe, would more effectively warm high latitudes, provide an additional heat source to mid-latitude continental interiors, and reduce the latitudinal temperature gradient. We present a hypothesis based on the positive phase of the modern Arctic Oscillation as one possible high-latitude influence. In short, that prolonged low pressure over the Arctic Ocean would have warmed mid-latitude continental interiors and drastically reduced the Arctic Ocean's ice cover, thus producing conditions consistent with proxy climate indicators for the Paleogene greenhouse interval.
Dalton, J.; Flower, C. E.; Brown, J.; Gonzalez-Meler, M. A.; Whelan, C.
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.
März, C.; Stratmann, A.; Eckert, S.; Schnetger, B.; Brumsack, H.-J.
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
Moore, Sue E; Huntington, Henry P
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
Hansen, Brage Bremset; Aanes, Ronny; Herfindal, Ivar; Kohler, Jack; Saether, Bernt-Erik
Across the Arctic, heavy rain-on-snow (ROS) is an "extreme" climatic event that is expected to become increasingly frequent with global warming. This has potentially large ecosystem implications through changes in snowpack properties and ground-icing, which can block the access to herbivores' winter food and thereby suppress their population growth rates. However, the supporting empirical evidence for this is still limited. We monitored late winter snowpack properties to examine the causes and consequences of ground-icing in a Svalbard reindeer (Rangifer tarandus platyrhynchus) metapopulation. In this high-arctic area, heavy ROS occurred annually, and ground-ice covered from 25% to 96% of low-altitude habitat in the sampling period (2000-2010). The extent of ground-icing increased with the annual number of days with heavy ROS (> or = 10 mm) and had a strong negative effect on reindeer population growth rates. Our results have important implications as a downscaled climate projection (2021-2050) suggests a substantial future increase in ROS and icing. The present study is the first to demonstrate empirically that warmer and wetter winter climate influences large herbivore population dynamics by generating ice-locked pastures. This may serve as an early warning of the importance of changes in winter climate and extreme weather events in arctic ecosystems.
Karcher, Michael; Harms, Ingo; Standring, William J F; Dowdall, Mark; Strand, Per
Current predictions as to the impacts of climate change in general and Arctic climate change in particular are such that a wide range of processes relevant to Arctic contaminants are potentially vulnerable. Of these, radioactive contaminants and the processes that govern their transport and fate may be particularly susceptible to the effects of a changing Arctic climate. This paper explores the potential changes in the physical system of the Arctic climate system as they are deducible from present day knowledge and model projections. As a contribution to a better preparedness regarding Arctic marine contamination with radioactivity we present and discuss how a changing marine physical environment may play a role in altering the current understanding pertaining to behavior of contaminant radionuclides in the marine environment of the Arctic region.
Geissler, Wolfram; Knies, Jochen
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
Schollert, Michelle; Kivimäenpää, Minna; Valolahti, Hanna M; Rinnan, Riikka
Biogenic volatile organic compound (BVOC) emissions are expected to change substantially because of the rapid advancement of climate change in the Arctic. BVOC emission changes can feed back both positively and negatively on climate warming. We investigated the effects of elevated temperature and shading on BVOC emissions from arctic plant species Empetrum hermaphroditum, Cassiope tetragona, Betula nana and Salix arctica. Measurements were performed in situ in long-term field experiments in subarctic and high Arctic using a dynamic enclosure system and collection of BVOCs into adsorbent cartridges analysed by gas chromatography-mass spectrometry. In order to assess whether the treatments had resulted in anatomical adaptations, we additionally examined leaf anatomy using light microscopy and scanning electron microscopy. Against expectations based on the known temperature and light-dependency of BVOC emissions, the emissions were barely affected by the treatments. In contrast, leaf anatomy of the studied plants was significantly altered in response to the treatments, and these responses appear to differ from species found at lower latitudes. We suggest that leaf anatomical acclimation may partially explain the lacking treatment effects on BVOC emissions at plant shoot-level. However, more studies are needed to unravel why BVOC emission responses in arctic plants differ from temperate species.
Bring, Arvid; Shiklomanov, Alexander; Lammers, Richard B.
The Arctic freshwater cycle is changing rapidly, which will require adequate monitoring of river flows to detect, observe, and understand changes and provide adaptation information. There has, however, been little detail about where the greatest flow changes are projected, and where monitoring therefore may need to be strengthened. In this study, we used a set of recent climate model runs and an advanced macro-scale hydrological model to analyze how flows across the continental pan-Arctic are projected to change and where the climate models agree on significant changes. We also developed a method to identify where monitoring stations should be placed to observe these significant changes, and compared this set of suggested locations with the existing network of monitoring stations. Overall, our results reinforce earlier indications of large increases in flow over much of the Arctic, but we also identify some areas where projections agree on significant changes but disagree on the sign of change. For monitoring, central and eastern Siberia, Alaska, and central Canada are hot spots for the highest changes. To take advantage of existing networks, a number of stations across central Canada and western and central Siberia could form a prioritized set. Further development of model representation of high-latitude hydrology would improve confidence in the areas we identify here. Nevertheless, ongoing observation programs may consider these suggested locations in efforts to improve monitoring of the rapidly changing Arctic freshwater cycle.
Kvie, Kjersti S.; Heggenes, Jan; Anderson, David G.; Kholodova, Marina V.; Sipko, Taras; Mizin, Ivan; Røed, Knut H.
In light of current debates on global climate change it has become important to know more on how large, roaming species have responded to environmental change in the past. Using the highly variable mitochondrial control region, we revisit theories of Rangifer colonization and propose that the High Arctic archipelagos of Svalbard, Franz Josef Land, and Novaia Zemlia were colonized by reindeer from the Eurasian mainland after the last glacial maximum. Comparing mtDNA control region sequences from the three Arctic archipelagos showed a strong genetic connection between the populations, supporting a common origin in the past. A genetic connection between the three archipelagos and two Russian mainland populations was also found, suggesting colonization of the Eurasian high Arctic archipelagos from the Eurasian mainland. The age of the Franz Josef Land material (>2000 years before present) implies that Arctic indigenous reindeer colonized the Eurasian Arctic archipelagos through natural dispersal, before humans approached this region. PMID:27880778
Salpin, Marie; Schnyder, Johann; Baudin, François; Suan, Guillaume; Labrousse, Loïc; Popescu, Speranta; Suc, Jean-Pierre
Paleoclimate records at high latitude in Arctic during the Paleogene SALPIN Marie1,2, SCHNYDER Johann1,2, BAUDIN François1,2, SUAN Guillaume3, LABROUSSE Loïc1,2, POPESCU Speranta4, SUC Jean-Pierre1,4 1: Sorbonne Universités, UPMC Univ Paris 06, UMR 7193, Institut des Sciences de la Terre Paris (iSTeP), F 75005, Paris, France 2: CNRS, UMR 7193, Institut des Sciences de la Terre Paris (iSTeP), F 75005 Paris, France 3: UCB Lyon 1, UMR 5276, LGLTPE, 69622 Villeurbanne Cedex, France 4: GEOBIOSTRATDATA.CONSULTING, 385 Route du Mas Rillier 69140 Rillieux la Pape, France The Paleogene is a period of important variations of the Earth climate system either in warming or cooling. The climatic optima of the Paleogene have been recognized both in continental and marine environment. This study focus on high latitudes of the northern hemisphere, in the Arctic Basin. The basin has had an influence on the Cenozoic global climate change according to its polar position. Is there a specific behaviour of the Arctic Basin with respect to global climatic stimuli? Are there possible mechanisms of coupling/decoupling of its dynamics with respect to the global ocean? To answer these questions a unique collection of sedimentary series of Paleogene age interval has been assembled from the Laurentian margin in Northern Yukon (Canada) and from the Siberian margin (New Siberian Islands). Selected continental successions of Paleocene-Eocene age were used to study the response of the Arctic system to known global events, e.g. the climatic optima of the Paleogene (the so-called PETM, ETM2 or the Azolla events). Two sections of Paleocene-Eocene age were sampled near the Mackenzie delta, the so-called Coal Mine (CoMi) and Caribou Hills (CaH) sections. The aim of the study is to precise the climatic fluctuations and to characterise the source rock potential of the basin, eventually linked to the warming events. This study is based on data of multi-proxy analyses: mineralogy on bulk and clay
Climate and...data coverage in the polar region such as Arctic. In this regard, coverage of instruments operated by NASA /CNES (i.e. JASON1/2, TOPEX) ends at...00-00-2014 4. TITLE AND SUBTITLE Wave Climate and Wave Mixing in the Marginal Ice Zones of Arctic Seas, Observations and Modelling 5a. CONTRACT
Arctic Environment Protection Strategy ANWR – Arctic National Wildlife Refuge AON – Arctic Observation Network CAFE – Corporate Average Fuel...environmentalists over drilling in the Arctic National Wildlife Refuge ( ANWR ), a 19 million acre refuge on the Arctic Coast estimated by the USGS to hold
DiMaggio, D.; Maslowski, W.; Osinski, R.; Roberts, A.; Clement Kinney, J. L.
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.
Koenigk, Torben; Brodeau, Laurent
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 the Arctic climate and interactions with lower latitudes under different levels of anthropogenic warming. The model simulations indicate an accelerated warming and ice extent reduction in the Arctic between the year-2030 and year-2015 simulations compared to the change between the year-2015 and year-2000 simulations. 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 under year-2015 and year-2030 conditions. This cooling is related to a strong reduction in the AMOC, itself due to 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.
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
Deal, Clara; Jin, Meibing
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
The presentation is divided into three parts. Part I is an overview of early expeditions to the High Arctic, and their political consequences at the time. The focus then shifts to the Geological Survey of Canada s mapping program in the North (Operation Franklin), and to the Polar Continental Shelf Project (PCSP), a unique organization that resides within the Government of Canada s Department of Natural Resources, and supports mapping projects and science investigations. PCSP is highlighted throughout the presentation so a description of mandate, budgets, and support infrastructure is warranted. In Part II, the presenter describes the planning required in advance of scientific deployments carried out in the Canadian High Arctic from the perspective of government and university investigators. Field operations and challenges encountered while leading arctic field teams in fly camps are also described in this part of the presentation, with particular emphasis on the 2008 field season. Part III is a summary of preliminary results obtained from a Polar Survey questionnaire sent out to members of the Arctic research community in anticipation of the workshop. The last part of the talk is an update on the analog program at the Canadian Space Agency, specifically, the Canadian Analog Research Network (CARN) and current activities related to Analog missions, 2009-2010.
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.
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
Wang, Qixiang; Fan, Xiaohui; Wang, Mengben
Elevation-dependent warming in high-elevation regions and Arctic amplification are of tremendous interest to many scientists who are engaged in studies in climate change. Here, using annual mean temperatures from 2781 global stations for the 1961–2010 period, we find that the warming for the world’s high-elevation stations (>500 m above sea level) is clearly stronger than their low-elevation counterparts; and the high-elevation amplification consists of not only an altitudinal amplification but also a latitudinal amplification. The warming for the high-elevation stations is linearly proportional to the temperature lapse rates along altitudinal and latitudinal gradients, as a result of the functional shape of Stefan-Boltzmann law in both vertical and latitudinal directions. In contrast, neither altitudinal amplification nor latitudinal amplification is found within the Arctic region despite its greater warming than lower latitudes. Further analysis shows that the Arctic amplification is an integrated part of the latitudinal amplification trend for the low-elevation stations (≤500 m above sea level) across the entire low- to high-latitude Northern Hemisphere, also a result of the mathematical shape of Stefan-Boltzmann law but only in latitudinal direction. PMID:26753547
Lachenbruch, A.H.; Marshall, B.V.
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.
Baring-Gould, I.; Corbus, D.
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.
This project aims to develop, apply and evaluate a regional Arctic System model (RASM) for enhanced decadal predictions. Its overarching goal is to advance understanding of the past and present states of arctic climate and to facilitate improvements in seasonal to decadal predictions. In particular, it will focus on variability and long-term change of energy and freshwater flows through the arctic climate system. The project will also address modes of natural climate variability as well as extreme and rapid climate change in a region of the Earth that is: (i) a key indicator of the state of global climate through polar amplification and (ii) which is undergoing environmental transitions not seen in instrumental records. RASM will readily allow the addition of other earth system components, such as ecosystem or biochemistry models, thus allowing it to facilitate studies of climate impacts (e.g., droughts and fires) and of ecosystem adaptations to these impacts. As such, RASM is expected to become a foundation for more complete Arctic System models and part of a model hierarchy important for improving climate modeling and predictions.
Liao, J.; Huey, L. G.; Liu, Z.; Tanner, D.; Cantrell, C. A.; Orlando, J. J.; Flocke, F. M.; Shepson, P. B.; Weinheimer, A. J.; Hall, S. R.; Beine, H.; Wang, Y.; Ingall, E. D.; Thompson, C. R.; Hornbrook, R. S.; Apel, E. C.; Fried, A.; Mauldin, L.; Smith, J. N.; Staebler, R. M.; Neuman, J. A.; Nowak, J. B.
Chlorine radicals are a strong atmospheric oxidant, particularly in polar regions where levels of hydroxyl radicals can be quite low. In the atmosphere, chlorine radicals expedite the degradation of methane and tropospheric ozone and the oxidation of mercury to more toxic forms. Here, we present direct measurements of molecular chlorine levels in the Arctic marine boundary layer in Barrow, Alaska, collected in the spring of 2009 over a six-week period using chemical ionization mass spectrometry. We detected high levels of molecular chlorine of up to 400 pptv. Concentrations peaked in the early morning and late afternoon and fell to near-zero levels at night. Average daytime molecular chlorine levels were correlated with ozone concentrations, suggesting that sunlight and ozone are required for molecular chlorine formation. Using a time-dependent box model, we estimated that the chlorine radicals produced from the photolysis of molecular chlorine on average oxidized more methane than hydroxyl radicals and enhanced the abundance of short-lived peroxy radicals. Elevated hydroperoxyl radical levels, in turn, promoted the formation of hypobromous acid, which catalyzed mercury oxidation and the breakdown of tropospheric ozone. Therefore, we propose that molecular chlorine exerts a significant effect on the atmospheric chemistry in the Arctic. While the formation mechanisms of molecular chlorine are not yet understood, the main potential sources of chlorine include snowpack, sea salt, and sea ice. There is recent evidence of molecular halogen (Br2 and Cl2) formation in the Arctic snowpack. The coverage and composition of the snow may control halogen chemistry in the Arctic. Changes of sea ice and snow cover in the changing climate may affect air-snow-ice interaction and have a significant impact on the levels of radicals, ozone, mercury and methane in the Arctic troposphere.
Kortsch, Susanne; Primicerio, Raul; Fossheim, Maria; Dolgov, Andrey V; Aschan, Michaela
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.
Mottram, Ruth; Rodehacke, Christian; Boberg, Fredrik; Langen, Peter; Sloth Madsen, Marianne; Høyer Svendsen, Synne; Yang, Shuting; Hesselbjerg Christensen, Jens; Olesen, Martin
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).
Hinzman, L. D.; Rawlins, M.; Serreze, M.; Vorosmarty, C. J.; Walsh, J. E.
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
Yim, Bo Young; Min, Hong Sik; Kug, Jong-Seong
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.
Ekwurzel, B.; Yona, L.; Natali, S.; Holmes, R. M.; Schuur, E.
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
Dethloff, Klaus; Rex, Markus; Shupe, Matthew
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
Gustine, David; Adams, Layne; Whalen, Mary; Pearce, John
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.
Galaktionov, K V
This review analyses the scarce available data on biodiversity and transmission of helminths in Arctic coastal ecosystems and the potential impact of climate changes on them. The focus is on the helminths of seabirds, dominant parasites in coastal ecosystems. Their fauna in the Arctic is depauperate because of the lack of suitable intermediate hosts and unfavourable conditions for species with free-living larvae. An increasing proportion of crustaceans in the diet of Arctic seabirds would result in a higher infection intensity of cestodes and acanthocephalans, and may also promote the infection of seabirds with non-specific helminths. In this way, the latter may find favourable conditions for colonization of new hosts. Climate changes may alter the composition of the helminth fauna, their infection levels in hosts and ways of transmission in coastal communities. Immigration of boreal invertebrates and fish into Arctic seas may allow the circulation of helminths using them as intermediate hosts. Changing migratory routes of animals would alter the distribution of their parasites, facilitating, in particular, their trans-Arctic transfer. Prolongation of the seasonal 'transmission window' may increase the parasitic load on host populations. Changes in Arctic marine food webs would have an overriding influence on the helminths' circulation. This process may be influenced by the predicted decreased of salinity in Arctic seas, increased storm activity, coastal erosion, ocean acidification, decline of Arctic ice, etc. Greater parasitological research efforts are needed to assess the influence of factors related to Arctic climate change on the transmission of helminths.
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-...
Shellito, C.; Kiehl, J.; Lamarque, J.; Sloan, L.
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.
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.
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
Cronin, Thomas M.; Cronin, Matthew A.
The Arctic Ocean is undergoing rapid climatic changes including higher ocean temperatures, reduced sea ice, glacier and Greenland Ice Sheet melting, greater marine productivity, and altered carbon cycling. Until recently, the relationship between climate and Arctic biological systems was poorly known, but this has changed substantially as advances in paleoclimatology, micropaleontology, vertebrate paleontology, and molecular genetics show that Arctic ecosystem history reflects global and regional climatic changes over all timescales and climate states (103–107 years). Arctic climatic extremes include 25°C hyperthermal periods during the Paleocene-Eocene (56–46 million years ago, Ma), Quaternary glacial periods when thick ice shelves and sea ice cover rendered the Arctic Ocean nearly uninhabitable, seasonally sea-ice-free interglacials and abrupt climate reversals. Climate-driven biological impacts included large changes in species diversity, primary productivity, species’ geographic range shifts into and out of the Arctic, community restructuring, and possible hybridization, but evidence is not sufficient to determine whether or when major episodes of extinction occurred.
Eric T. DeWeaver
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.
Bintanja, R.; van der Linden, E. C.; Hazeleger, W.
Amplified Arctic warming is one of the key features of climate change. It is evident in observations as well as in climate model simulations. Usually referred to as Arctic amplification, it is generally recognized that the surface albedo feedback governs the response. However, a number of feedback mechanisms play a role in AA, of which those related to the prevalent near-surface inversion have received relatively little attention. Here we investigate the role of the near-surface thermal inversion, which is caused by radiative surface cooling in autumn and winter, on Arctic warming. We employ idealized climate change experiments using the climate model EC-Earth together with ERA-Interim reanalysis data to show that boundarylayer mixing governs the efficiency by which the surface warming signal is 'diluted' to higher levels. Reduced vertical mixing, as in the stably stratified inversion layer in Arctic winter, thus amplifies surface warming. Modelling results suggest that both shortwave—through the (seasonal) interaction with the sea ice feedback—and longwave feedbacks are affected by boundary-layer mixing, both in the Arctic and globally, with the effect on the shortwave feedback dominating. The amplifying effect will decrease, however, with climate warming because the surface inversion becomes progressively weaker. We estimate that the reduced Arctic inversion has slowed down global warming by about 5% over the past 2 decades, and we anticipate that it will continue to do so with ongoing Arctic warming.
Bintanja, R.; van der Linden, E. C.; Hazeleger, W.
Amplified Arctic warming is one of the key features of climate change. It is evident in observations as well as in climate model simulations. Usually referred to as Arctic amplification, it is generally recognized that the surface albedo feedback governs the response. However, a number of feedback mechanisms play a role in AA, of which those related to the prevalent near-surface inversion have received relatively little attention. Here we investigate the role of the near-surface thermal inversion, which is caused by radiative surface cooling in autumn and winter, on Arctic warming. We employ idealized climate change experiments using the climate model EC-Earth together with ERA-Interim reanalysis data to show that boundary-layer mixing governs the efficiency by which the surface warming signal is `diluted' to higher levels. Reduced vertical mixing, as in the stably stratified inversion layer in Arctic winter, thus amplifies surface warming. Modelling results suggest that both shortwave—through the (seasonal) interaction with the sea ice feedback—and longwave feedbacks are affected by boundary-layer mixing, both in the Arctic and globally, with the effect on the shortwave feedback dominating. The amplifying effect will decrease, however, with climate warming because the surface inversion becomes progressively weaker. We estimate that the reduced Arctic inversion has slowed down global warming by about 5% over the past 2 decades, and we anticipate that it will continue to do so with ongoing Arctic warming.
Maslowski, Wieslaw; Cassano, John J.; Gutowski, Jr., William J.; Lipscomb, William H.; Nijssen, Bart; Roberts, Andrew; Robertson, William; Tulaczyk, Slawek; Zeng, Xubin
The primary outcome of the project was the development of the Regional Arctic System Model (RASM) and evaluation of its individual model components, coupling among them and fully coupled model results. Overall, we have demonstrated that RASM produces realistic mean and seasonal surface climate as well as its interannual and decadal variability and trends.
Prost, Stefan; Smirnov, Nickolay; Fedorov, Vadim B.; Sommer, Robert S.; Stiller, Mathias; Nagel, Doris; Knapp, Michael; Hofreiter, Michael
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.
Bring, Arvid; Destouni, Georgia
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.
The article presents and briefly analyses the issue of the European Union's perspective on the problems of the climate change in the Arctic region and its geopolitical consequences. Offering an overview of the main documents in this area, the article concludes that the EU policy towards the Arctic is closely related with perceiving the climate change in polar regions not only in terms of new possibilities, but also as a source of new threats for the international environment
The article presents and briefly analyses the issue of the European Union's perspective on the problems of the climate change in the Arctic region and its geopolitical consequences. Offering an overview of the main documents in this area, the article concludes that the EU policy towards the Arctic is closely related with perceiving the climate change in polar regions not only in terms of new possibilities, but also as a source of new threats for the international environment.
Cohen, J. L.; Zhang, X.
The Arctic has warmed more than twice as fast as the global average, a phenomenon known as Arctic amplification (AA). These profound changes to the Arctic system have coincided with a period of ostensibly more frequent events of extreme weather across the Northern Hemisphere mid-latitudes, including extreme heat and rainfall events and recent severe winters. The possible link between Arctic change and mid-latitude weather has spurred a rush of new observational and modeling studies. These studies have argued that heavy precipitation events and heat waves are at least partially attributable to Arctic warming. A growing number of recent studies even argue that recent extreme winter weather is related to AA. In part due to the high impact of extreme weather on our society, some of these studies linking AA to the increased frequency of extreme weather have garnered public and media attention. At the same time, uncertainties from the large intrinsic variability of the system, the short observational record due to the recentness of AA and the shortcomings of global climate models have also resulted in much skepticism in any argued links between AA and severe weather. This in turn has resulted in a number of workshops trying to frame the problem and laying the groundwork to improve our understanding of Arctic-mid-latitude linkages and accurate attribution of extreme weather events. Although these workshops identified existing problems and difficulties, and provided broad recommendations, they did not synthesize the diversified research results to identify where community consensus and gaps exist. Therefore we have assembled many of the leading scientists researching Arctic-mid-latitude linkages as part of a US CLIVAR working group. Through the three-year efforts of this working group, we will use the outcome of the previous workshops and newly planned activities to guide the synthesis efforts, coordinate on-going research to fill out key gaps, and provide specific
Nahrgang, Jasmine; Varpe, Oystein; Korshunova, Ekaterina; Murzina, Svetlana; Hallanger, Ingeborg G; Vieweg, Ireen; Berge, Jørgen
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.
Brohan, P.; Ward, C.; Willetts, G.; Wilkinson, C.; Allan, R.; Wheeler, D.
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.
Brohan, P.; Ward, C.; Willetts, G.; Wilkinson, C.; Allan, R.; Wheeler, D.
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.
Provencher, J F; Braune, B M; Gilchrist, H G; Forbes, M R; Mallory, M L
Baseline data on trace element concentrations are lacking for many species of Arctic marine birds. We measured essential and non-essential element concentrations in Arctic tern (Sterna paradisaea) liver tissue and brain tissue (mercury only) from Canada's High Arctic, and recorded the presence/absence of gastrointestinal parasites during four different phases of the breeding season. Arctic terns from northern Canada had similar trace element concentrations to other seabird species feeding at the same trophic level in the same region. Concentrations of bismuth, selenium, lead and mercury in Arctic terns were high compared to published threshold values for birds. Selenium and mercury concentrations were also higher in Arctic terns from northern Canada than bird species sampled in other Arctic areas. Selenium, mercury and arsenic concentrations varied across the time periods examined, suggesting potential regional differences in the exposure of biota to these elements. For unknown reasons, selenium concentrations were significantly higher in birds with gastrointestinal parasites as compared to those without parasites, while bismuth concentrations were higher in Arctic terns not infected with gastrointestinal parasites.
Grand Graversen, Rune
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.
The Arctic Ocean is central to the understanding of climate and global environmental change. As a critical component of the Earth system, the Arctic region both influences and responds rapidly to natural variations and to human-induced perturbations, such as warming, contaminant accumulation, and associated impacts. While it is clear that there are dramatic changes occurring in the Arctic, the interactions between the air and surfaces are still not understood. The international, multidisciplinary Ocean-Atmosphere-Sea Ice-Snowpack (OASIS) program addresses the knowledge gaps and coordinates studies of Arctic atmosphere-surface interactions and associated feedbacks to the climate system. OASIS is planned as a long term science program for the next decade. OASIS is linked to a number of international organizations and activities, including AMAP, the IGBP programs IGAC under the AICI (Air Ice Chemical Interactions) activity, and SOLAS (Surface Ocean Lower Atmosphere Study), and the WCRP project CliC (Climate and Cryosphere). The abundant snowpack in the Arctic is not just a white cover: an array of intriguing reactions has been observed within and on snowpacks and sea-ice during springtime Arctic sunrise that dramatically influences the composition of the atmosphere. Building on these discoveries, the OASIS research approach is aimed at a better understanding of air-surface chemical exchange in the context of a changing climate. Fundamental physical, chemical, and biologically-mediated chemical exchange processes will be studied to answer questions such as: Will climate change increase or decrease the amount of mercury deposited in the Arctic? How will warming affect regional and global climate? How are sea ice and snow chemistry and physics changing? What is the role of biological processes in producing reactive atmospheric gases? What is the role of sea-salt in ozone depletion? What are ecological and human health impacts of toxic materials such as mercury and
Strzelecki, Matt; Long, Antony; Lloyd, Jerry
Most sediment budget studies in paraglacial, High Arctic, environments have focussed attention on quantifying sediment fluxes in glacial and fluvial catchments. In contrast, little attention has been paid to the functioning of the paraglacial coastal zone with existing models of coastal change based on relict systems developed in mid latitude settings. The pristine coasts of Spitsbergen provided a superb opportunity to quantify how High Arctic coasts are respondingto rapid climate warming and associated paraglacial landscape transformation. In this paper we reconstruct the development of the paraglacial coasts in Petuniabukta and Adolfbukta, the northernmost bays of Billefjorden, central Spitsbergen. The study area is characterized by a sheltered location, a semi-arid, sub-polar climate, limited wave fetch and tidal range, and rapid retreat of all surrounding glaciers. Using a combination of geomorphological, sedimentological, remote sensing and dating methods, we study the processes controlling the coastal zone development over annual, century and millennial timescales. Interannual changes observed between 2008-2010 show that gravel barriers in the study area are resilient to the impacts of local storms and the operation of sea-ice processes. In general, the processes controlling the short-term barrier development often operate in the opposite direction to the landforming patterns visible in the longer-term evolution. Over multi-decadal timescales, since the end of the Little Ice Age. we observe drammatic changes in sediment flux and coastal response under an interval characterised by a warming climate, retreating local ice masses, a shortened winter sea-ice season and melting permafrost. A new approach of dating juvenile mollusc found in uplifted marine barriers led to the better understating of the Late Holocene evolution of a Petuniabukta coastal zone and its reaction to deglaciation, glacioisostatic uplift and sea-level fluctuations. We propose a new
Stidham, Thomas A.; Eberle, Jaelyn J.
Fossils attributable to the extinct waterfowl clade Presbyornithidae and the large flightless Gastornithidae from the early Eocene (~52–53 Ma) of Ellesmere Island, in northernmost Canada are the oldest Cenozoic avian fossils from the Arctic. Except for its slightly larger size, the Arctic presbyornithid humerus is not distinguishable from fossils of Presbyornis pervetus from the western United States, and the Gastornis phalanx is within the known size range of mid-latitude individuals. The occurrence of Presbyornis above the Arctic Circle in the Eocene could be the result of annual migration like that of its living duck and geese relatives, or it may have been a year-round resident similar to some Eocene mammals on Ellesmere and some extant species of sea ducks. Gastornis, along with some of the mammalian and reptilian members of the Eocene Arctic fauna, likely over-wintered in the Arctic. Despite the milder (above freezing) Eocene climate on Ellesmere Island, prolonged periods of darkness occurred during the winter. Presence of these extinct birds at both mid and high latitudes on the northern continents provides evidence that future increases in climatic warming (closer to Eocene levels) could lead to the establishment of new migratory or resident populations within the Arctic Circle. PMID:26867798
Stidham, Thomas A.; Eberle, Jaelyn J.
Fossils attributable to the extinct waterfowl clade Presbyornithidae and the large flightless Gastornithidae from the early Eocene (~52–53 Ma) of Ellesmere Island, in northernmost Canada are the oldest Cenozoic avian fossils from the Arctic. Except for its slightly larger size, the Arctic presbyornithid humerus is not distinguishable from fossils of Presbyornis pervetus from the western United States, and the Gastornis phalanx is within the known size range of mid-latitude individuals. The occurrence of Presbyornis above the Arctic Circle in the Eocene could be the result of annual migration like that of its living duck and geese relatives, or it may have been a year-round resident similar to some Eocene mammals on Ellesmere and some extant species of sea ducks. Gastornis, along with some of the mammalian and reptilian members of the Eocene Arctic fauna, likely over-wintered in the Arctic. Despite the milder (above freezing) Eocene climate on Ellesmere Island, prolonged periods of darkness occurred during the winter. Presence of these extinct birds at both mid and high latitudes on the northern continents provides evidence that future increases in climatic warming (closer to Eocene levels) could lead to the establishment of new migratory or resident populations within the Arctic Circle.
Ford, James D.
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.
Taylor, Mark A.; Roesler, Erika Louise; Bosler, Peter Andrew
The Department of Energy’s (DOE) Biological and Environmental Research project, “Water Cycle and Climate Extremes Modeling” is improving our understanding and modeling of regional details of the Earth’s water cycle. Sandia is using high resolution model behavior to investigate storms in the Arctic.
McGuire, A.D.; Clein, J.S.; Melillo, J.M.; Kicklighter, D.W.; Meier, R.A.; Vorosmarty, C.J.; Serreze, M.C.
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
Hurwitz, Margaret M.; Newman, P. A.; Garfinkel, C. I.
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.
Genet, H.; McGuire, A. D.; He, Y.; Johnson, K.; Wylie, B. K.; Pastick, N. J.; Zhuang, Q.; Zhu, Z.
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
Eliseev, A. V.; Semenov, V. A.
In the course of forecasting future climate changes in the Arctic Region based on calculations and an ensemble of the state-of-the-art global climate models, the results depend on the method of construction the statistics from the models.
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.
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.
Koo, J.; Wang, Y.; Jiang, T.; Deng, Y.; Oltmans, S. J.; Solberg, S.
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.
Nielsen, Jennifer L.; Ruggerone, Gregory T.; Zimmerman, Christian E.
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.
Jones, Colin G; Wyser, Klaus; Ullerstig, Anders; Willén, Ulrika
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.
Moseley, Gina; Edwards, R. Lawrence; Cheng, Hai; Lu, Yanbin; Spoetl, Christoph
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.
Hein, Catherine L; Ohlund, Gunnar; Englund, Göran
Novel communities will be formed as species with a variety of dispersal abilities and environmental tolerances respond individually to climate change. Thus, models projecting future species distributions must account for species interactions and differential dispersal abilities. We developed a species distribution model for Arctic char Salvelinus alpinus, a freshwater fish that is sensitive both to warm temperatures and to species interactions. A logistic regression model using lake area, mean annual air temperature (1961-1990), pike Esox lucius and brown trout Salmo trutta occurrence correctly classified 95 % of 467 Swedish lakes. We predicted that Arctic char will lose 73 % of its range in Sweden by 2100. Predicted extinctions could be attributed both to simulated temperature increases and to projected pike invasions. The Swedish mountains will continue to provide refugia for Arctic char in the future and should be the focus of conservation efforts for this highly valued fish.
Howell, Fergus; Haywood, Alan; Pickering, Steven
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
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, Frederick 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.
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.
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...
Norris, G.; Head, M.J.
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.
Rumpf, Sabine B; Semenchuk, Philipp R; Dullinger, Stefan; Cooper, Elisabeth J
The Arctic is one of the ecosystems most affected by climate change; in particular, winter temperatures and precipitation are predicted to increase with consequent changes to snow cover depth and duration. Whether the snow-free period will be shortened or prolonged depends on the extent and temporal patterns of the temperature and precipitation rise; resulting changes will likely affect plant growth with cascading effects throughout the ecosystem. We experimentally manipulated snow regimes using snow fences and shoveling and assessed aboveground size of eight common high arctic plant species weekly throughout the summer. We demonstrated that plant growth responded to snow regime, and that air temperature sum during the snow free period was the best predictor for plant size. The majority of our studied species showed periodic growth; increases in plant size stopped after certain cumulative temperatures were obtained. Plants in early snow-free treatments without additional spring warming were smaller than controls. Response to deeper snow with later melt-out varied between species and categorizing responses by growth forms or habitat associations did not reveal generic trends. We therefore stress the importance of examining responses at the species level, since generalized predictions of aboveground growth responses to changing snow regimes cannot be made.
Ernakovich, Jessica G; Hopping, Kelly A; Berdanier, Aaron B; Simpson, Rodney T; Kachergis, Emily J; Steltzer, Heidi; Wallenstein, Matthew D
Global climate change is already having significant impacts on arctic and alpine ecosystems, and ongoing increases in temperature and altered precipitation patterns will affect the strong seasonal patterns that characterize these temperature-limited systems. The length of the potential growing season in these tundra environments is increasing due to warmer temperatures and earlier spring snow melt. Here, we compare current and projected climate and ecological data from 20 Northern Hemisphere sites to identify how seasonal changes in the physical environment due to climate change will alter the seasonality of arctic and alpine ecosystems. We find that although arctic and alpine ecosystems appear similar under historical climate conditions, climate change will lead to divergent responses, particularly in the spring and fall shoulder seasons. As seasonality changes in the Arctic, plants will advance the timing of spring phenological events, which could increase plant nutrient uptake, production, and ecosystem carbon (C) gain. In alpine regions, photoperiod will constrain spring plant phenology, limiting the extent to which the growing season can lengthen, especially if decreased water availability from earlier snow melt and warmer summer temperatures lead to earlier senescence. The result could be a shorter growing season with decreased production and increased nutrient loss. These contrasting alpine and arctic ecosystem responses will have cascading effects on ecosystems, affecting community structure, biotic interactions, and biogeochemistry.
Bertram, K. B.
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
Ma, Jianmin; Hung, Hayley; Tian, Chongguo; Kallenborn, Roland
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.
Stoddart, Mark C J; Smith, Jillian
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
Pommereau, J.-P.; Goutail, F.; Lefèvre, F.; Pazmino, A.; Adams, C.; Dorokhov, V.; Eriksen, P.; Kivi, R.; Stebel, K.; Zhao, X.; van Rozendael, M.
An unprecedented ozone loss occurred in the Arctic in spring 2011. The details of the event are re-visited from the twice-daily total ozone and NO2 columns measurements of the eight SAOZ/NDACC (Système d'Analyse par Observation Zénitale/Network for Detection of Atmospheric Composition Changes) stations in the Arctic. It is shown that the total ozone depletion in the polar vortex reached 38% (approx. 170 DU) by the end of March that is larger than the 30% of the previous record in 1996. Asides from the long extension of the cold stratospheric NAT PSC period, the amplitude of the event is shown to be resulting from a record daily total ozone loss rate of 0.7% day-1 after mid-February, never seen before in the Arctic but similar to that observed in the Antarctic over the last 20 yr. This high loss rate is attributed to the absence of NOx in the vortex until the final warming, in contrast to all previous winters where, as shown by the early increase of NO2 diurnal increase, partial renoxification is occurring by import of NOx or HNO3 from the outside after minor warming episodes, leading to partial chlorine deactivation. The cause of the absence of renoxification and thus of high loss rate, is attributed to a vortex strength similar to that of the Antarctic but never seen before in the Arctic. The total ozone reduction on 20 March was identical to that of the 2002 Antarctic winter, which ended around 20 September, and a 15-day extension of the cold period would have been enough to reach the mean yearly amplitude of the Antarctic ozone hole. However there is no sign of trend since 1994, neither in PSC volume, early winter denitrification, late vortex renoxification, and vortex strength nor in total ozone loss. The unprecedented large Arctic ozone loss in 2011 appears to resulting from an extreme meteorological event and there is no indication of possible strengthening related to climate change.
Pommereau, J.-P.; Goutail, F.; Lefèvre, F.; Pazmino, A.; Adams, C.; Dorokhov, V.; Eriksen, P.; Kivi, R.; Stebel, K.; Zhao, X.; van Roozendael, M.
An unprecedented ozone loss occurred in the Arctic in spring 2011. The details of the event are revisited from the twice-daily total ozone and NO2 column measurements of the eight SAOZ/NDACC (Système d'Analyse par Observation Zénithale/Network for Detection of Atmospheric Composition Changes) stations in the Arctic. It is shown that the total ozone depletion in the polar vortex reached 38% (approx. 170 DU) by the end of March, which is larger than the 30% of the previous record in 1996. Aside from the long extension of the cold stratospheric NAT PSC period, the amplitude of the event is shown to be resulting from a record daily total ozone loss rate of 0.7% d-1 after mid-February, never seen before in the Arctic but similar to that observed in the Antarctic over the last 20 yr. This high loss rate is attributed to the absence of NOx in the vortex until the final warming, in contrast to all previous winters where, as shown by the early increase of NO2 diurnal increase, partial renoxification occurs by import of NOx or HNO3 from the outside after minor warming episodes, leading to partial chlorine deactivation. The cause of the absence of renoxification and thus of high loss rate, is attributed to a vortex strength similar to that of the Antarctic but never seen before in the Arctic. The total ozone reduction on 20 March was identical to that of the 2002 Antarctic winter, which ended around 20 September, and a 15-day extension of the cold period would have been enough to reach the mean yearly amplitude of the Antarctic ozone hole. However there is no sign of trend since 1994, either in PSC (polar stratospheric cloud) volume (volume of air cold enough to allow formation of PSCs), early winter denitrification, late vortex renoxification, and vortex strength or in total ozone loss. The unprecedented large Arctic ozone loss in 2011 appears to result from an extreme meteorological event and there is no indication of possible strengthening related to climate change.
Eric T. DeWeaver
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
Tsyganov, Andrey N; Nijs, Ivan; Beyens, Louis
Soil testate amoebae assemblages in a grassland area at Zackenberg (Northeast Greenland) were subjected to simulated climate-warming during the growing season using the Free-Air Temperature Increase technique. Samples were collected in upper (0 - 3cm) and deeper (3 - 6cm) soil horizons. Mean temperature elevations at 2.5 and 7.5 cm depth were 2.58 ± SD 1.11 and 2.13±SD 0.77°C, respectively, and did not differ significantly. Soil moisture in the top 11cm was not affected by the warming. During the manipulation, the densities of living amoebae and empty shells were higher in the experimental plots but only in the upper layer. Possibly, testate amoebae in the deeper layer were limited by other factors, suggesting that warming enhances the carrying capacity only in favourable conditions. Species richness, on the other hand, was only increased in the deeper horizon. Warming did not change the percentage of individuals belonging to small-sized species in any of the living assemblages, contrary to our expectation that those species would quickly increase their density. However, in the empty shell assemblages, the proportion of small-sized individuals in the experimental plots was higher in both layers, indicating a rapid, transient increase in small amoebae before the first sampling date. Changes in successional state of testate amoebae assemblages in response to future climate change might thus be ephemeral, whereas alterations in density and species richness might be more sustained.
Fortin, Marie-Claude; Gajewski, Konrad
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.
Alekseev, Genrikh; Pnyushkov, Andrey; Ivanov, Nikolai; Balakin, Andrey
The enhanced warming in the Arctic began in the middle of 1990s and maximized in 2007. During this period an abrupt shrinking of the summer ice extent occurred and significant positive anomaly of temperature in Atlantic Water (AW) layer in the Arctic Basin expanded over larger area. This climate shift coincided with the resumption of intensive field studies in the Arctic Ocean. The observations collected during the last two decades and especially in the frame of IPY 2007/08 international projects provided an enormous database of oceanographic, sea ice and atmospheric data that makes it possible to determine the climate shift in the marine Arctic, to compare the recent anomalies to those in 1970s and to link the Arctic climate shift to the global climate change. Observations show that since 1990 the surface air temperature (SAT) in the marine Arctic increased rapidly. The CMIP3 ensemble of climate models is seemed to underestimate the rise of SAT especially in summer. Time series of the AW layer parameters along with its pathway over the Arctic Basin during the period of 1930-2009 were compiled in order to trace the development of anomalies. Mean decadal oceanographic fields for 1990s and 2000s and for 2007 year were produced and its anomalies from 1970s were estimated. Rapid climate changes in the marine Arctic in 1990-2000s can not be accounted solely for the anthropogenic effect since the actually observed changes exceed the predictions of the global climate models. Our analysis emphasizes an important role of the increasing summer heat fluxes, as well as the influence of low latitude ocean variability and the solar activity. Other conclusion is that abrupt warming in the marine Arctic stopped in 2008-2009 and it is necessary to continue the monitoring of further changes. The studies were fulfilled in the frame of the AARI IPY projects, Applied Science Program of the Roshydromet and with support of the Russian Foundation for Basic Research (projects 06-05-64054a
Wang, Shaoyin; Liu, Jiping
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.
Johannessen, O M; Miles, M W
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.
Sand, M.; Berntsen, T. K.; von Salzen, K.; Flanner, M. G.; Langner, J.; Victor, D. G.
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.
Sundseth, Kyrre; Pacyna, Jozef M; Banel, Anna; Pacyna, Elisabeth G; Rautio, Arja
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.
Sundseth, Kyrre; Pacyna, Jozef M.; Banel, Anna; Pacyna, Elisabeth G.; Rautio, Arja
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
Howell, Fergus W.; Haywood, Alan M.; Dowsett, Harry J.; Pickering, Steven J.
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.
Hollesen, Jørgen; Matthiesen, Henning; Møller, Anders Bjørn; Westergaard-Nielsen, Andreas; Elberling, Bo
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.
Hollesen, Jørgen; Matthiesen, Henning; Møller, Anders Bjørn; Westergaard-Nielsen, Andreas; Elberling, Bo
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
Rolland, N.; Porinchu, D.; MacDonald, G.; Moser, K.
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
Koo, Ja-Ho; Wang, Yuhang; Jiang, Tianyu; Deng, Yi; Oltmans, Samuel J.; Solberg, Sverre
Near-surface ozone depletion events (ODEs) generally occur in the Arctic spring, and the frequency shows large interannual variations. We use surface ozone measurements at Barrow, Alert, and Zeppelinfjellet to analyze if their variations are due to climate variability. In years with frequent ODEs at Barrow and Alert, the western Pacific (WP) teleconnection pattern is usually in its negative phase, during which the Pacific jet is strengthened but the storm track originated over the western Pacific is weakened. Both factors tend to reduce the transport of ozone-rich air mass from midlatitudes to the Arctic, creating a favorable environment for the ODEs. The correlation of ODE frequencies at Zeppelinfjellet with WP indices is higher in the 2000s, reflecting stronger influence of the WP pattern in recent decade to cover ODEs in broader Arctic regions. We find that the WP pattern can be used to diagnose ODE changes and subsequent environmental impacts in the Arctic spring.
Willis, M. J.; Melkonian, A. K.; Pritchard, M. E.; Golos, E. M.
The ~2000 glaciers and icecaps on the islands of the Russian High Arctic cover a total area of about 55,600 km2. Infrequent studies have indicated that these glaciers have lost a total of ~100 km3 of ice, equivalent to about 0.3 mm of sea level, since 1960. Recent GRACE observations suggest that the Severnaya Zemlya Archipelago and Franz Josef Archipelago are approximately in balance, while the "Main Ice Sheet" of the Novaya Zemlya archipelago is losing mass at a small rate. This glacier complex, on the northern island of the archipelago is the largest ice mass in Europe (23,800 km2) and the third largest polar ice masses on the planet after the Antarctic and Greenland Ice sheets. The glaciers, ice caps and icefields of the Russian High Arctic are a major reservoir of fresh water and under climate scenarios that involve warming, a potentially increasing source of mass for sea level rise. We examine the response of the glaciers of the Russian High Arctic to recent, pronounced atmospheric warming. Digitized topographic maps, ASTER Digital Elevation Models (DEMs), cloud free ICESat returns and several DEMs calculated from recent high-resolution imagery pairs are used to provide a time-series and maps of ice surface elevation change rates between the mid-1980s' and 2012 for the "Main Ice Sheet" on Novaya Zemlya and the Franz Josef Land Archipelago. DEMs are co-registered to a common horizontal base and corrected for biases due to varying reference frames and datums. Elevation change rates are calculated on a pixel-by-pixel basis and are integrated over each ice complex to provide volume change rates. Volume rates are converted to mass rates assuming an ice density of 900 kg/m3. Glacier speeds are derived from pairs of ASTER images between 2000 and 2012 and from higher resolution imagery between 2010 and 2012. Cloudy conditions often hamper our ability to make good pairs and problems occur when there are no bedrock outcrops, which are typically used to check for
Pasha Karami, Mehdi; de Vernal, Anne; Hu, Xianmin; Myers, Paul G.
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.
González, G.; Rivera, F.; Makarova, O.; Gould, W. A.
Frost heave action contributes to the formation of non-sorted circles in the High Arctic. Non-sorted circles tend to heave more than the surrounding tundra due to deeper thaw and the formation of ice lenses. Thus, the geomorphology, soils and vegetation on the centers of the patterned-ground feature (non-sorted circles) as compared to the surrounding soils (inter-circles) can be different. We established a decomposition experiment to look at in situ decay rates of the most dominant graminoid species on non-sorted circles and adjacent inter-circle soils along a climatic gradient in the Canadian High Arctic as a component of a larger study looking at the biocomplexity of small-featured patterned ground ecosystems. Additionally, we investigated variation in soil chemical properties and biota, including soil microarthropods and microbial composition and biomass, as they relate to climate, topographic position, and litter decay rates. Our three sites locations, from coldest to warmest, are Isachsen, Ellef Ringnes Island (ER), NU (bioclimatic subzone A); Mould Bay (MB), Prince Patrick Island, NT (bioclimatic subzone B), and Green Cabin (GC), Aulavik National Park, Thomsen River, Banks Island, NT (bioclimatic subzone C). Our sample design included the selection of 15 non-sorted circles and adjacent inter-circle areas within the zonal vegetation at each site (a total of 90 sites), and a second set of 3 non-sorted circles and adjacent inter-circle areas in dry, mesic and wet tundra at each of the sites. Soil invertebrates were sampled at each site using both pitfall traps, soil microbial biomass was determined using substrate induced respiration and bacterial populations were determined using the most probable number method. Decomposition rates were measured using litterbags and as the percent of mass remaining of Carex misandra, Luzula nivalis and Alopecuris alpinus in GC, MB and ER, respectively. Our findings indicate these graminoid species decayed significantly over
Sand, M.; Berntsen, T.; von Salzen, K.; Flanner, M.; Langner, J.; Victor, D. G.
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.
Sand, M.; Berntsen, T.; von Salzen, K.; Flanner, M.; Langner, J.; Victor, D. G.
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.
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.
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.
Serykh, Ilya; Byshev, Vladimir; Neiman, Victor; Sidorova, Alexandra; Sonechkin, Dmitry
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
Zhang, Tao; Yao, Yi-Feng
This study assessed the diversity and distribution of endophytic fungal communities associated with the leaves and stems of four vascular plant species in the High Arctic using 454 pyrosequencing with fungal-specific primers targeting the ITS region. Endophytic fungal communities showed high diversity. The 76,691 sequences obtained belonged to 250 operational taxonomic units (OTUs). Of these OTUs, 190 belonged to Ascomycota, 50 to Basidiomycota, 1 to Chytridiomycota, and 9 to unknown fungi. The dominant orders were Helotiales, Pleosporales, Capnodiales, and Tremellales, whereas the common known fungal genera were Cryptococcus, Rhizosphaera, Mycopappus, Melampsora, Tetracladium, Phaeosphaeria, Mrakia, Venturia, and Leptosphaeria. Both the climate and host-related factors might shape the fungal communities associated with the four Arctic plant species in this region. These results suggested the presence of an interesting endophytic fungal community and could improve our understanding of fungal evolution and ecology in the Arctic terrestrial ecosystems. PMID:26067836
Zhang, Tao; Yao, Yi-Feng
This study assessed the diversity and distribution of endophytic fungal communities associated with the leaves and stems of four vascular plant species in the High Arctic using 454 pyrosequencing with fungal-specific primers targeting the ITS region. Endophytic fungal communities showed high diversity. The 76,691 sequences obtained belonged to 250 operational taxonomic units (OTUs). Of these OTUs, 190 belonged to Ascomycota, 50 to Basidiomycota, 1 to Chytridiomycota, and 9 to unknown fungi. The dominant orders were Helotiales, Pleosporales, Capnodiales, and Tremellales, whereas the common known fungal genera were Cryptococcus, Rhizosphaera, Mycopappus, Melampsora, Tetracladium, Phaeosphaeria, Mrakia, Venturia, and Leptosphaeria. Both the climate and host-related factors might shape the fungal communities associated with the four Arctic plant species in this region. These results suggested the presence of an interesting endophytic fungal community and could improve our understanding of fungal evolution and ecology in the Arctic terrestrial ecosystems.
Kutz, Susan J; Jenkins, Emily J; Veitch, Alasdair M; Ducrocq, Julie; Polley, Lydden; Elkin, Brett; Lair, Stephane
Climate change is influencing the structure and function of natural ecosystems around the world, including host-parasite interactions and disease emergence. Understanding the influence of climate change on infectious disease at temperate and tropical latitudes can be challenging because of numerous complicating biological, social, and political factors. Arctic and Subarctic regions may be particularly good models for unraveling the impacts of climate change on parasite ecology because they are relatively simple systems with low biological diversity and few other complicating anthropogenic factors. We examine some changing dynamics of host-parasite interactions at high latitudes and use these to illustrate a framework for approaching understanding, preventing, and mitigating climate change impacts on infectious disease, including zoonoses, in wildlife.
Bock, Judith K.
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…
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
1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Wave Climate and Wave Mixing in the Marginal Ice Zones of...inclination angle, altitude etc. With change in the inclination angle, global coverage and repeat cycle also change . An 2 inclination angle close... climate is available over the entire period of existence of the marginal Arctic ice zones. Figure 1. Altimeter missions by Agency (1985-2015
Klaus, Daniel; Dethloff, Klaus; Dorn, Wolfgang; Rinke, Annette
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
Laxon, Seymour; Peacock, Neil; Smith, Doug
Possible future changes in Arctic sea ice cover and thickness, and consequent changes in the ice-albedo feedback, represent one of the largest uncertainties in the prediction of future temperature rise. Knowledge of the natural variability of sea ice thickness is therefore critical for its representation in global climate models. Numerical simulations suggest that Arctic ice thickness varies primarily on decadal timescales owing to changes in wind and ocean stresses on the ice, but observations have been unable to provide a synoptic view of sea ice thickness, which is required to validate the model results. Here we use an eight-year time-series of Arctic ice thickness, derived from satellite altimeter measurements of ice freeboard, to determine the mean thickness field and its variability from 65 degrees N to 81.5 degrees N. Our data reveal a high-frequency interannual variability in mean Arctic ice thickness that is dominated by changes in the amount of summer melt, rather than by changes in circulation. Our results suggest that a continued increase in melt season length would lead to further thinning of Arctic sea ice.
Warming, thawing and disappearance of permafrost have accelerated in recent decades damaging engineered structures and raising public concerns. By the middle of the 21st century anthropogenic climate change may cause 2 to 3 C warming of the frozen ground, 10% to 16% reduction of the total permafrost area, 30% to 50% deepening of the active-layer thickness, and shifts between the permafrost zones due to cumulative effect of changing surface temperature, soil moisture, and vegetation. Such changes will have important implications for northern engineering and infrastructure built upon permafrost. The foundations supporting engineered structures are designed for the constant climatic conditions with construction-specific safety factor, which in the practice of the cold-region engineering varies typically from 5% to 60% with respect to the bearing capacity. In the zone of discontinuous permafrost a 2.0 C rise in air temperature may decrease the bearing capacity of frozen ground under buildings by more than a half. This may have important consequences for the infrastructure and particularly for residential buildings constructed in the permafrost zone between 1950 and 1990 in northern Russian cities Vorkuta, Yakytsk, Norylsk, and Magadan. Many of them are already weakened or damaged, which may in part be attributed to the effect of climate change. Susceptibility of permafrost to environmental hazards associated with thermokarst, ground settlement, and other destructive cryogenic processes may be crudely evaluated using the geocryological hazard index, which is the combination of the predicted for the future climate relative change in the active-layer thickness and the ground ice content. Predictive maps constructed for scenarios of climate change indicated that several population centers (Barrow, Inuvik), river terminals on the arctic coast of Russia (Salekhard, Igarka, Dudinka, Tiksi), and gas production complexes with associated infrastructure in northwest Siberia fall
Gosse, John; Braschi, Lea; Rybczynski, Natalia; Lakeman, Thomas; Zimmerman, Susan; Finkel, Robert; Barendregt, Rene; Matthews, John
The Beaufort Formation comprises an extensive (1200 km long, more than 1 km thick) clastic wedge that formed during the Pliocene along the western Canadian Arctic Archipelago (CAA). In the western Arctic, the Ballast Brook (BB) site on Banks Is. exposes more than 20 km of section through the sandy and pebble sandy braided stream deposits with detrital organic beds. Farther north, Beaufort Fm fluvial and estuarine facies have been examined on Meighen Is. In the high Arctic, high terrace gravels (450 m high surface) at the Fyles Leaf Bed (FLB) and Beaver Pond (BP) sites on Ellesmere Is. are not considered part of the Beaufort Fm but have similar paleoenvironmental records. Fossil plant and faunal material from these sediments is often very well preserved and provides evidence of a boreal-type forest and peatlands. The BP fossil site preserves the remains of fossil vertebrates including fish, frog, horse, beaver, deerlet, and black bear, consistent with a boreal type forest habitat. The FLB site has recently yielded the first fossil evidence for a High Arctic camel, identified with the help of collagen fingerprinting from a fragmentary limb bone (tibia). Paleoenvironmental reconstruction of the Ellesmere sites has yielded a Mean Annual Temperature of between 14 to 22 degrees Celsius warmer than today. Minimum cosmogenic nuclide burial ages of 3.4 and 3.8 Ma obtained for the BP and FLB sites, respectively, are consistent with vertebrate and floral biostratigraphic evidence. The paleoenvironmental records from the Beaufort Fm in the western CAA sites have revealed a similar ecosystem with noteworthy differences in MAT and perhaps seasonality. New burial ages from Meighen Is. indicate a maximum age of 6.1 Ma, consistent with yet much older than previous age estimates, but supportive of paleomagnetic and biostratigraphy at the same location. The age differences may account for some of the interpreted variations in paleoenvironments, in addition to spatial differences in
Miller, James R.; Russell, Gary L.; Hansen, James E. (Technical Monitor)
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
Pálsson, Snæbjörn; Hersteinsson, Páll; Unnsteinsdóttir, Ester R; Nielsen, Ólafur K
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.
Hori, M. E.
Cyclone activities are governed by many boundary conditions, such as the underlying SST or sea ice, the relative heating between the continent and the ocean, and their relative location against the jet stream to name a few. All these factors and their seasonal march is prone to change under the future global warming condition. Especially in the Arctic, the timing of sea ice melting and freezing, seasonal change in snow cover, and the location of upper level jets all contribute towards a change in cyclone seasonal distribution and extreme events. Here, we use a Langrangean method of detecting cyclones and their activity under the historical and rcp 4.5 scenario of 8 CMIP5 climate models to assess the change in Arctic cyclone activities. We find that while the models show weaker cyclone activities than observation and inter-model difference is large in some cases, they simulate the seasonal cycle and extreme events reasonably well. In the winter season under the global warming scenario, many models exhibits a northeastward shift in mid-latitude storm track resulting in mode cyclones entering the Arctic from the mid-latitudes. There is also a marked increase in the number of cyclones in the Barents/Kara Sea where correlation with sea ice is suspected. During the summer season, a large change in the Arctic cyclone activity located near the North Pole is evident in many models. This change in Arctic cyclone is due to contribution of more cyclogenesis within the Arctic circle. In this presentation, we also look at other seasons and the seasonal march of the cyclone activity within the Arctic and its interaction with the mid-latitudes. We also document the change in extreme events under the climate models.
Panchen, Zoe A; Gorelick, Root
The pace of climate change in the Arctic is dramatic, with temperatures rising at a rate double the global average. The timing of flowering and fruiting (phenology) is often temperature dependent and tends to advance as the climate warms. Herbarium specimens, photographs, and field observations can provide historical phenology records and have been used, on a localised scale, to predict species' phenological sensitivity to climate change. Conducting similar localised studies in the Canadian Arctic, however, poses a challenge where the collection of herbarium specimens, photographs, and field observations have been temporally and spatially sporadic. We used flowering and seed dispersal times of 23 Arctic species from herbarium specimens, photographs, and field observations collected from across the 2.1 million km(2) area of Nunavut, Canada, to determine (1) which monthly temperatures influence flowering and seed dispersal times; (2) species' phenological sensitivity to temperature; and (3) whether flowering or seed dispersal times have advanced over the past 120 years. We tested this at different spatial scales and compared the sensitivity in different regions of Nunavut. Broadly speaking, this research serves as a proof of concept to assess whether phenology-climate change studies using historic data can be conducted at large spatial scales. Flowering times and seed dispersal time were most strongly correlated with June and July temperatures, respectively. Seed dispersal times have advanced at double the rate of flowering times over the past 120 years, reflecting greater late-summer temperature rises in Nunavut. There is great diversity in the flowering time sensitivity to temperature of Arctic plant species, suggesting climate change implications for Arctic ecological communities, including altered community composition, competition, and pollinator interactions. Intraspecific temperature sensitivity and warming trends varied markedly across Nunavut and could
Prost, Stefan; Guralnick, Robert P; Waltari, Eric; Fedorov, Vadim B; Kuzmina, Elena; Smirnov, Nickolay; van Kolfschoten, Thijs; Hofreiter, Michael; Vrieling, Klaas
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
Miller, James R.; Russell, Gary L.
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.
Skidmore, M L; Foght, J M; Sharp, M J
The debris-rich basal ice layers of a high Arctic glacier were shown to contain metabolically diverse microbes that could be cultured oligotrophically at low temperatures (0.3 to 4 degrees C). These organisms included aerobic chemoheterotrophs and anaerobic nitrate reducers, sulfate reducers, and methanogens. Colonies purified from subglacial samples at 4 degrees C appeared to be predominantly psychrophilic. Aerobic chemoheterotrophs were metabolically active in unfrozen basal sediments when they were cultured at 0.3 degrees C in the dark (to simulate nearly in situ conditions), producing (14)CO(2) from radiolabeled sodium acetate with minimal organic amendment (> or =38 microM C). In contrast, no activity was observed when samples were cultured at subfreezing temperatures (< or =-1.8 degrees C) for 66 days. Electron microscopy of thawed basal ice samples revealed various cell morphologies, including dividing cells. This suggests that the subglacial environment beneath a polythermal glacier provides a viable habitat for life and that microbes may be widespread where the basal ice is temperate and water is present at the base of the glacier and where organic carbon from glacially overridden soils is present. Our observations raise the possibility that in situ microbial production of CO(2) and CH(4) beneath ice masses (e.g., the Northern Hemisphere ice sheets) is an important factor in carbon cycling during glacial periods. Moreover, this terrestrial environment may provide a model for viable habitats for life on Mars, since similar conditions may exist or may have existed in the basal sediments beneath the Martian north polar ice cap.
'We travelled in the winter after the return of daylight and did not go into fixed camp until spring, when the ice broke up. There was good hunting on the way, seals, beluga, walrus, bear.' (From Old Merkrusârk's account of his childhood's trek from Baffin Island to Northwest Greenland, told to Knud Rasmussen on Saunders Island in 1904) Five thousand years ago people moving eastwards from Beringia spread over the barrens of the Canadian high Arctic. This was the first of three waves of prehistoric Arctic 'cultures', which eventually reached Greenland. The passage into Greenland has to go through the northernmost and most hostile part of the country with a 5 month Polar night, and to understand this extraordinary example of human behaviour and endurance, it has been customary to invoke a more favourable (warmer) climate. This presentation suggests that land-fast sea ice, i.e. stationary sea ice anchored to the coast, is among the most important environmental factors behind the spread of prehistoric polar cultures. The ice provides the road for travelling and social communion - and access to the most important source of food, the ocean. In the LongTerm Project (2006 and 2007) we attempted to establish a Holocene record for sea ice variations along oceanic coasts in northernmost Greenland. Presently the coasts north of 80° N are beleaguered by year-round sea ice - for ten months this is land-fast ice, and only for a period in the stormy autumn months are the coasts exposed to pack-ice. This presentation Land-fast ice - as opposed to pack-ice - is a product of local temperatures, but its duration over the year, and especially into the daylight season, is also conditioned by other factors, notably wind strength. In the geological record we recognize long lasting land-fast ice by two absences: absence of traces of wave action (no beach formation), which, however, can also be a result of pack-ice along the coast; - and absence of driftwood on the shore (land-fast ice
Tedesco, M.; Mote, T.; Fettweis, X.; Hanna, E.; Jeyaratnam, J.; Booth, J. F.; Datta, R.; Briggs, K.
Large-scale atmospheric circulation controls the mass and energy balance of the Greenland ice sheet through its impact on radiative budget, runoff and accumulation. Here, using reanalysis data and the outputs of a regional climate model, we show that the persistence of an exceptional atmospheric ridge, centered over the Arctic Ocean, was responsible for a poleward shift of runoff, albedo and surface temperature records over the Greenland during the summer of 2015. New records of monthly mean zonal winds at 500 hPa and of the maximum latitude of ridge peaks of the 5,700+/-50 m isohypse over the Arctic were associated with the formation and persistency of a cutoff high. The unprecedented (1948-2015) and sustained atmospheric conditions promoted enhanced runoff, increased the surface temperatures and decreased the albedo in northern Greenland, while inhibiting melting in the south, where new melting records were set over the past decade. Subject terms: Earth sciences Atmospheric science Climate science
Jayer, Sophie; Le Divenah, Claudie; Rosetti, Alexandra
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: email@example.com 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
Chaudhary, Nitin; Smith, Benjamin; Miller, Paul
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
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
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
Oechel; Vourlitis; Hastings; Zulueta; Hinzman; Kane
Long-term sequestration of carbon in Alaskan Arctic tundra ecosystems was reversed by warming and drying of the climate in the early 1980s, resulting in substantial losses of terrestrial carbon. But recent measurements suggest that continued warming and drying has resulted in diminished CO2 efflux, and in some cases, summer CO2 sink activity. Here we compile summer CO2 flux data for two Arctic ecosystems from 1960 to the end of 1998. The results show that a return to summer sink activity has come during the warmest and driest period observed over the past four decades, and indicates a previously undemonstrated capacity for ecosystems to metabolically adjust to long-term (decadal or longer) changes in climate. The mechanisms involved are likely to include changes in nutrient cycling, physiological acclimation, and population and community reorganization. Nevertheless, despite the observed acclimation, the Arctic ecosystems studied are still annual net sources of CO2 to the atmosphere of at least 40 g C m(-2) yr(-1), due to winter release of CO2, implying that further climate change may still exacerbate CO2 emissions from Arctic ecosystems.
Kraemer, Lisa D; Berner, James E; Furgal, Christopher M
Many northern indigenous populations are exposed to elevated concentrations of contaminants through traditional food and many of these contaminants come from regions exterior to the Arctic. Global contaminant pathways include the atmosphere, ocean currents, and river outflow, all of which are affected by climate. In addition to these pathways, precipitation, animal availability, UV radiation, cryosphere degradation and human industrial activities in the North are also affected by climate change. The processes governing contaminant behaviour in both the physical and biological environment are complex and therefore, in order to understand how climate change will affect the exposure of northern people to contaminants, we must have a better understanding of the processes that influence how contaminants behave in the Arctic environment. Furthermore, to predict changes in contaminant levels, we need to first have a good understanding of current contaminant levels in the Arctic environment, biota and human populations. For this reason, it is critical that both spatial and temporal trends in contaminant levels are monitored in the environment, biota and human populations from all the Arctic regions.
Min, Seung-Ki; Zhang, Xuebin; Zwiers, Francis
The Arctic and northern subpolar regions are critical for climate change. Ice-albedo feedback amplifies warming in the Arctic, and fluctuations of regional fresh water inflow to the Arctic Ocean modulate the deep ocean circulation and thus exert a strong global influence. By comparing observations to simulations from 22 coupled climate models, we find influence from anthropogenic greenhouse gases and sulfate aerosols in the space-time pattern of precipitation change over high-latitude land areas north of 55 degrees N during the second half of the 20th century. The human-induced Arctic moistening is consistent with observed increases in Arctic river discharge and freshening of Arctic water masses. This result provides new evidence that human activity has contributed to Arctic hydrological change.
Prowse, Terry D; Wrona, Frederick J; Reist, James D; Gibson, John J; Hobbie, John E; Lévesque, Lucie M J; Vincent, Warwick F
In general, the arctic freshwater-terrestrial system will warm more rapidly than the global average, particularly during the autumn and winter season. The decline or loss of many cryospheric components and a shift from a nival to an increasingly pluvial system will produce numerous physical effects on freshwater ecosystems. Of particular note will be reductions in the dominance of the spring freshet and changes in the intensity of river-ice breakup. Increased evaporation/evapotranspiration due to longer ice-free seasons, higher air/water temperatures and greater transpiring vegetation along with increase infiltration because of permafrost thaw will decrease surface water levels and coverage. Loss of ice and permafrost, increased water temperatures and vegetation shifts will alter water chemistry, the general result being an increase in lotic and lentic productivity. Changes in ice and water flow/levels will lead to regime-specific increases and decreases in habitat availability/quality across the circumpolar Arctic.
Swann, Abigail L; Fung, Inez Y; Levis, Samuel; Bonan, Gordon B; Doney, Scott C
Arctic climate is projected to change dramatically in the next 100 years and increases in temperature will likely lead to changes in the distribution and makeup of the Arctic biosphere. A largely deciduous ecosystem has been suggested as a possible landscape for future Arctic vegetation and is seen in paleo-records of warm times in the past. Here we use a global climate model with an interactive terrestrial biosphere to investigate the effects of adding deciduous trees on bare ground at high northern latitudes. We find that the top-of-atmosphere radiative imbalance from enhanced transpiration (associated with the expanded forest cover) is up to 1.5 times larger than the forcing due to albedo change from the forest. Furthermore, the greenhouse warming by additional water vapor melts sea-ice and triggers a positive feedback through changes in ocean albedo and evaporation. Land surface albedo change is considered to be the dominant mechanism by which trees directly modify climate at high-latitudes, but our findings suggest an additional mechanism through transpiration of water vapor and feedbacks from the ocean and sea-ice.
Swann, Abigail L.; Fung, Inez Y.; Levis, Samuel; Bonan, Gordon B.; Doney, Scott C.
Arctic climate is projected to change dramatically in the next 100 years and increases in temperature will likely lead to changes in the distribution and makeup of the Arctic biosphere. A largely deciduous ecosystem has been suggested as a possible landscape for future Arctic vegetation and is seen in paleo-records of warm times in the past. Here we use a global climate model with an interactive terrestrial biosphere to investigate the effects of adding deciduous trees on bare ground at high northern latitudes. We find that the top-of-atmosphere radiative imbalance from enhanced transpiration (associated with the expanded forest cover) is up to 1.5 times larger than the forcing due to albedo change from the forest. Furthermore, the greenhouse warming by additional water vapor melts sea-ice and triggers a positive feedback through changes in ocean albedo and evaporation. Land surface albedo change is considered to be the dominant mechanism by which trees directly modify climate at high-latitudes, but our findings suggest an additional mechanism through transpiration of water vapor and feedbacks from the ocean and sea-ice. PMID:20080628
Sundqvist, H. S.; Kaufman, D. S.; Balascio, N. L.
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
Bujak, J. P.; Brinkhuis, H.
The marine and terrestrial biotas of northern Alaska and the Canadian Beaufort Mackenzie Basin (BMB) are intimately linked to changes in the climate and oceanography of the region. These changes can be reconstructed using palynological data from surface sections and numerous exploration wells drilled in the region over the past 30 years. During the Late Triassic to Early Eocene, marine dinoflagellate cyst (dinocyst) and terrestrial miospore (pollen and spore) palynomorphs were diverse and abundant across the region, reflecting the presence of a relatively warm and productive polar ocean that was fringed by extensive forests. The region was heated by northward-flowing Pacific currents, but lay north of the Arctic Circle and had seasonal 24 hour winter darkness and summer daylight. No modern analogue exists for this environment. A dramatic change occurred at the end of the Early Eocene as global climate shifted from the greenhouse towards the modern icehouse world. This had a particularly strong effect in high latitudes. A succession of major extinction events reflected falling sea and air temperatures in the Arctic and progressively eliminated marine and terrestrial species from the region. These events can be correlated with Eocene cooling steps known from the North Atlantic, where they had a milder effect, and provide a chronostratigraphic link between the regions. By Oligocene time the Arctic populations were strongly impoverished, but Miocene warming permitted the immigration of cold-temperate species including marine dinoflagellates and terrestrial angiosperms. Following this warm phase, the marine and terrestrial populations became increasingly restricted as air and water temperatures fell during the Plio-Pleistocene, leading to the modern highly endemic Arctic biotas.
Bring, Arvid; Destouni, Georgia
The Arctic is subject to growing economic and political interest. Meanwhile, its climate and water systems are in rapid transformation. In this paper, we review and extend a set of studies on climate model results, hydro-climatic change, and hydrological monitoring systems. Results indicate that general circulation model (GCM) projections of drainage basin temperature and precipitation have improved between two model generations. However, some inaccuracies remain for precipitation projections. When considering geographical priorities for monitoring or adaptation efforts, our results indicate that future projections by GCMs and recent observations diverge regarding the basins where temperature and precipitation changes currently are the most pronounced and where they will be so in the future. Regarding late twentieth-century discharge changes in major Arctic rivers, data generally show excess of water relative to precipitation changes. This indicates a possible contribution to sea-level rise of river water that was previously stored in permafrost or groundwater. The river contribution to the increasing Arctic Ocean freshwater inflow is similar in magnitude to the separate contribution from glaciers, which underlines the importance of considering all possible sources of freshwater when assessing sea-level change. We further investigate monitoring systems and find a lack of harmonized water chemistry data, which limits the ability to understand the origin and transport of nutrients, carbon and sediment to the sea. To provide adequate information for research and policy, Arctic hydrological and hydrochemical monitoring needs to be extended, better integrated and made more accessible. Further water-focused data and modeling efforts are required to resolve the source of excess discharge in Arctic rivers. Finally, improvements in climate model parameterizations are needed, in particular for precipitation projections.
Goetz, S. J.
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
Mod, Heidi K.; Luoto, Miska
Climate change has been observed to expand distributions of woody plants in many areas of arctic and alpine environments—a phenomenon called shrubification. New spatial arrangements of shrubs cause further changes in vegetation via changing dynamics of biotic interactions. However, the mediating influence of shrubification is rarely acknowledged in predictions of tundra vegetation change. Here, we examine possible warming-induced landscape-level vegetation changes in a high-latitude environment using species distribution modelling (SDM), specifically concentrating on the impacts of shrubification on ambient vegetation. First, we produced estimates of current shrub and tree cover and forecasts of their expansion under climate change scenarios to be incorporated to SDMs of 116 vascular plants. Second, the predictions of vegetation change based on the models including only abiotic predictors and the models including abiotic, shrub and tree predictors were compared in a representative test area. Based on our model predictions, abundance of woody plants will expand, thus decreasing predicted species richness, amplifying species turnover and increasing the local extinction risk for ambient vegetation. However, the spatial variation demonstrated in our predictions highlights that tundra vegetation can be expected to show a wide variety of different responses to the combined effects of warming and shrubification, depending on the original plant species pool and environmental conditions. We conclude that realistic forecasts of the future require acknowledging the role of shrubification in warming-induced tundra vegetation change.
Yamanouchi, Takashi; Takano, Toshiaki; Shiobara, Masataka; Okamoto, Hajime; Koike, Makoto; Ukita, Jinro
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
Stauffer, B. W.; Fitzhugh, W. W.; Krupnik, I.; Mannes, J.; Rusk, K.
The Arctic: A Friend Acting Strangely is a new exhibit being 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 issues. The exhibit will open to the public in Summer 2004 and is the third component of the series. The other two components are about El Niño (El Niño's Powerful Reach) and atmospheric chemistry (Change is in the Air). The Arctic exhibit's underlying theme is that current global change is causing such rapid shifts in Arctic weather and the polar environment that it has become `strange,' - or unpredictable - to its residents. The speed of change in Arctic ice and climate patterns, ocean and terrestrial ecosystems, and wildlife creates a great challenge for polar scientists; but it also advances beyond the experience and memory of northern indigenous people, who know it so well. The key issues the NMNH team faces in preparing the new exhibit are: how to document and display the forces and consequences of rapid change; how to make complex scientific processes and research comprehensible to visitors; and how to engage the general public in the on-going discussion. Because current shifts in the Arctic environment have been observed and recorded in much detail by scientists and Native residents alike, this topic offers unique opportunities beyond the museum presentation, including outreach through public programs and the Internet. The exhibit is being developed jointly by the NMNH Arctic Studies Center and Office of the Exhibits, and in close collaboration with NOAA' Office of Arctic Research, NSF' new Study of Environmental Arctic Change (SEARCH) initiative, and NASA's Earth Science Enterprise. Exhibit components will include objects, text, graphic panels, video, and a computer interactive. Special efforts will be made to present the voices and opinions of Arctic indigenous people who experience new challenges to their traditional subsistence
Svendsen, Sarah Hagel; Lindwall, Frida; Michelsen, Anders; Rinnan, Riikka
Emissions of biogenic volatile organic compounds (BVOCs) from terrestrial ecosystems are important for the atmospheric chemistry and the formation of secondary organic aerosols, and may therefore influence the climate. Global warming is predicted to change patterns in precipitation and plant species compositions, especially in arctic regions where the temperature increase will be most pronounced. These changes are potentially highly important for the BVOC emissions but studies investigating the effects are lacking. The aim of this study was to investigate the quality and quantity of BVOC emissions from a high arctic soil moisture gradient extending from dry tundra to a wet fen. Ecosystem BVOC emissions were sampled five times in the July-August period using a push-pull enclosure technique, and BVOCs trapped in absorbent cartridges were analyzed using gas chromatography-mass spectrometry. Plant species compositions were estimated using the point intercept method. In order to take into account important underlying ecosystem processes, gross ecosystem production, ecosystem respiration and net ecosystem production were measured in connection with chamber-based BVOC measurements. Highest emissions of BVOCs were found from vegetation communities dominated by Salix arctica and Cassiope tetragona, which had emission profiles dominated by isoprene and monoterpenes, respectively. These results show that emissions of BVOCs are highly dependent on the plant cover supported by the varying soil moisture, suggesting that high arctic BVOC emissions may affect the climate differently if soil water content and plant cover change.
Comiso, Josefino C.; Hall, Dorothy K.
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.
Comiso, Josefino C; Hall, Dorothy K
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.
Comiso, Josefino C; Hall, Dorothy K
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
quantify the environmental drivers of rapid coastal erosion in the Arctic, and to begin developing predictive models of future rates of coastal erosion ...wave) energy in driving coastal erosion in the Arctic. We are combining high-resolution observations of coastline retreat with meteorological and...content, ice-wedge polygon spacing, and the thermal properties of bluff materials; 2) time-lapse photography to observe coastal erosion processes in
McClelland, J. W.; Griffin, C. G.; Holmes, R. M.; Peterson, B. J.; Raymond, P. A.; Spencer, R. G.; Striegl, R. G.; Tank, S. E.
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.
Peros, Matthew C.; Gajewski, Konrad
A detailed pollen record from Victoria Island provides the first quantitative Holocene climate reconstruction from the western Canadian Arctic. The pollen percentage data indicate that Arctic herbs increased over the Holocene in response to long-term cooling. The influx of locally and regionally derived pollen grains varies throughout the core and tracks several major changes observed in the biogenic silica record from Arolik Lake, Alaska, and the GISP2 ice-core, suggesting that climate change closely controlled Arctic plant productivity. Using modern analogue and transfer function techniques, we generated quantitative reconstructions of mean July temperature and total annual precipitation for the past 10 000 years, to place recent climate changes within the context of Holocene climate variability. The quantitative reconstructions indicate that July temperature cooled by 1-1.5 °C during the Holocene. The pollen-based reconstructions record an increase in temperature of ˜0.5 °C over the last 100 years, and the pollen percentage and influx data indicate impacts of recent warming on the regional vegetation.
Hinzman, L. D.
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.
Parkinson, Claire L.
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.
Doyle, J. G.; Lesins, G.; Thackray, C. P.; Perro, C.; Nott, G. J.; Duck, T. J.; Damoah, R.; Drummond, J. R.
The meridional transport of water vapor into the High Arctic, accompanied by dry enthalpy and clouds, impacts the surface radiative forcing. The evolution of one such moist intrusion over 9-11 February 2010 is presented. The event is analyzed using a unique blend of measurements including a new pan-Arctic retrieval of column water vapor from the Microwave Humidity Sounders, water vapor profiles from a Raman lidar and a ground-based microwave radiometer at the Polar Environment Atmospheric Research Laboratory (PEARL), in Eureka (80°N, 86°W), on Ellesmere Island in the Canadian High Arctic. A radiation model reveals the intrusion is associated with a 17 W m-2 average increase in downwelling longwave irradiance. Optically thin clouds, as observed by the lidar, contribute a further 20 W m-2 to the downwelling longwave irradiance at their peak. Intrusion events are shown to be a regular occurrence in the Arctic winter with implications for the understanding of the mechanisms driving Arctic Amplification.
Hansen, Kaj M.; Christensen, Jesper H.; Brandt, Jørgen
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%.
Saito, Kazuyuki; Zhang, Tingjun; Yang, Daqing; Marchenko, Sergei; Barry, Roger G; Romanovsky, Vladimir; Hinzman, Larry
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.
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.
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.
Ivy, Diane J.; Solomon, Susan; Calvo, Natalia; Thompson, David W. J.
We present observational evidence for linkages between extreme Arctic stratospheric ozone anomalies in March and Northern Hemisphere tropospheric climate in spring (March–April). Springs characterized by low Arctic ozone anomalies in March are associated with a stronger, colder polar vortex and circulation anomalies consistent with the positive polarity of the Northern Annular Mode/North Atlantic Oscillation in March and April. The associated spring tropospheric circulation anomalies indicate a poleward shift of zonal winds at 500 hPa over the North Atlantic. Furthermore, correlations between March Arctic ozone and March–April surface temperatures reveal certain regions where a surprisingly large fraction of the interannual variability in spring surface temperatures is associated with interannual variability in ozone. We also find that years with low March Arctic ozone in the stratosphere display surface maximum daily temperatures in March–April that are colder than normal over southeastern Europe and southern Asia, but warmer than normal over northern Asia, adding to the warming from increasing well-mixed greenhouse gases in those locations. The results shown here do not establish causality, but nevertheless suggest that March stratospheric ozone is a useful indicator of spring averaged (March–April) tropospheric climate in certain Northern Hemispheric regions.
Orellana, Mónica V; Matrai, Patricia A; Leck, Caroline; Rauschenberg, Carlton D; Lee, Allison M; Coz, Esther
Marine microgels play an important role in regulating ocean basin-scale biogeochemical dynamics. In this paper, we demonstrate that, in the high Arctic, marine gels with unique physicochemical characteristics originate in the organic material produced by ice algae and/or phytoplankton in the surface water. The polymers in this dissolved organic pool assembled faster and with higher microgel yields than at other latitudes. The reversible phase transitions shown by these Arctic marine gels, as a function of pH, dimethylsulfide, and dimethylsulfoniopropionate concentrations, stimulate the gels to attain sizes below 1 μm in diameter. These marine gels were identified with an antibody probe specific toward material from the surface waters, sized, and quantified in airborne aerosol, fog, and cloud water, strongly suggesting that they dominate the available cloud condensation nuclei number population in the high Arctic (north of 80°N) during the summer season. Knowledge about emergent properties of marine gels provides important new insights into the processes controlling cloud formation and radiative forcing, and links the biology at the ocean surface with cloud properties and climate over the central Arctic Ocean and, probably, all oceans.
Orellana, Mónica V.; Matrai, Patricia A.; Leck, Caroline; Rauschenberg, Carlton D.; Lee, Allison M.; Coz, Esther
Marine microgels play an important role in regulating ocean basin-scale biogeochemical dynamics. In this paper, we demonstrate that, in the high Arctic, marine gels with unique physicochemical characteristics originate in the organic material produced by ice algae and/or phytoplankton in the surface water. The polymers in this dissolved organic pool assembled faster and with higher microgel yields than at other latitudes. The reversible phase transitions shown by these Arctic marine gels, as a function of pH, dimethylsulfide, and dimethylsulfoniopropionate concentrations, stimulate the gels to attain sizes below 1 μm in diameter. These marine gels were identified with an antibody probe specific toward material from the surface waters, sized, and quantified in airborne aerosol, fog, and cloud water, strongly suggesting that they dominate the available cloud condensation nuclei number population in the high Arctic (north of 80°N) during the summer season. Knowledge about emergent properties of marine gels provides important new insights into the processes controlling cloud formation and radiative forcing, and links the biology at the ocean surface with cloud properties and climate over the central Arctic Ocean and, probably, all oceans. PMID:21825118
Overland, J. E.
Three important features of recent Arctic change are the rather uniform pattern of Arctic temperature amplification in response to greenhouse gas forcing, the modification of atmospheric temperature and wind patterns over newly sea-ice-free regions, and the possible increased linkage between Arctic climate and sub-arctic weather. An important argument for anthropogenic forcing of recent Arctic change is the model predicted rather uniform increases in Arctic temperatures, in contrast to more regional temperature maximums associated with intrinsic climate variability patterns such as those which occurred during the 1930s Arctic warming. Sea-ice-free areas at the end of summer are allowing: added heat and moisture transport into the troposphere as documented during the recent Japanese vessel Mirai cruises, decreased boundary layer stratification, and modification of wind flow through thermal wind processes. Winter 2009-2010 and December 2010 showed a unique connectivity between the Arctic and more southern weather when the typical polar vortex was replaced by high geopotential heights over the central Arctic and low heights over mid-latitudes that resulted in record snow and low temperatures, a Warm Arctic-Cold Continents pattern. A major challenge of Arctic meteorology is to understand the interaction of forced changes such as loss of sea ice and land impacts with intrinsic climate patterns such as the North Atlantic Oscillation and Pacific North American climate patterns. Could persistent shifts in Arctic climate be triggered by a combination of a gradual upward trend in temperature, an extreme event e.g. fortuitous timing in the natural variability of the atmospheric or ocean general circulation, and Arctic specific feedbacks? Scientific progress on both issues requires sustained decadal observations.
Nielsen, Uffe N; Wall, Diana H
The polar regions are experiencing rapid climate change with implications for terrestrial ecosystems. Here, despite limited knowledge, we make some early predictions on soil invertebrate community responses to predicted twenty-first century climate change. Geographic and environmental differences suggest that climate change responses will differ between the Arctic and Antarctic. We predict significant, but different, belowground community changes in both regions. This change will be driven mainly by vegetation type changes in the Arctic, while communities in Antarctica will respond to climate amelioration directly and indirectly through changes in microbial community composition and activity, and the development of, and/or changes in, plant communities. Climate amelioration is likely to allow a greater influx of non-native species into both the Arctic and Antarctic promoting landscape scale biodiversity change. Non-native competitive species could, however, have negative effects on local biodiversity particularly in the Arctic where the communities are already species rich. Species ranges will shift in both areas as the climate changes potentially posing a problem for endemic species in the Arctic where options for northward migration are limited. Greater soil biotic activity may move the Arctic towards a trajectory of being a substantial carbon source, while Antarctica could become a carbon sink.
Sparrow, E. B.; Chase, M. J.; Demientieff, S.; Pfirman, S. L.; Brunacini, J.
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.
Vavrus, Stephen J.
The thermodynamic sea ice code in a coupled atmosphere-mixed layer ocean GCM has been altered to allow the presence of open water within an ice pack (leads) and a prescribed turbulent oceanic heat flux at the ice bottom. Two experiments with the GCM are then performed: one with leads included and one without. A comparison between the two model runs is presented, in addition to a comparison between observations and the simulation with leads. Selected sea ice and atmospheric variables in the high-latitude Northern Hemisphere are analyzed to assess the sensitivity of these climatic components to the presence of leads and to identify feedback mechanisms that are introduced by leads.The inclusion of leads causes Northern Hemispheric sea ice concentration to decrease in every season, with year-round statistically significant reductions at the highest latitude band (81°N). Using the improved sea ice code, the model's simulation of sea ice concentration in the central Arctic is consistent with observations in every season. Simulated summertime sea ice concentration at 81°N averages 93.8%, which agrees well with observations. There is a pronounced longitudinal variation to the lead fraction in summer, with the smallest values (0.01) neat the Canadian Archipelago and the largest (0.25) north of the East Siberian Sea. Consistent with observations, the model produces wintertime turbulent sensible heat fluxes over leads that are one to two orders of magnitude larger than over adjacent sea ice and of the opposite sign. Annual solar radiation absorption by leads in the central Arctic is 1.8 times as large as over adjacent sea ice, resulting in a summertime shortwave energy gain of over 2.5 W m2 at 8 1°N compared to the model run without leads.The inclusion of leads causes thicker sea ice in every season, because the very rapid ice growth rate in the leads is translated into enhanced accretion at the bottom of adjacent sea ice once a prescribed minimum lead fraction is reached
Erikson, L.H.; Storlazzi, C.D.; Jensen, R.E.
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.
Zhuang, Qianlai; Schlosser, Courtney; Melillo, Jerry; Walter, Katey
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.
Bruggeman, Jason E; Swem, Ted; Andersen, David E; Kennedy, Patricia L; Nigro, Debora
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
Lau, Maggie C.Y.; Stackhouse, B.; Layton, Alice C.; ...
The transition of Arctic carbon-rich cryosols into methane (CH₄)-emitting wetlands due to global warming is a rising concern. However, the spatially predominant mineral cryosols and their CH₄ emission potential are poorly understood. Fluxes measured in situ and estimated under laboratory conditions coupled with -omics analysis indicate (1) mineral cryosols in the Canadian high Arctic contain atmospheric CH₄-oxidizing bacteria; (2) the atmospheric CH⁺ uptake flux increases with ground temperature; and, as a result, (3) the atmospheric CH₄ sink strength will increase by a factor of 5-30 as the Arctic warms by 5-15 °C over a century. We demonstrated that acidic mineralmore » cryosols have previously unrecognized potential of negative CH₄ feedback.« less
Lau, Maggie C.Y.; Stackhouse, B.; Layton, Alice C.; Chauhan, Archana; Vishnivetskaya, T. A.; Chourey, Karuna; Mykytczuk, N. C.S.; Bennett, Phil C.; Lamarche-Gagnon, G.; Burton, N.; Renholm, J.; Hettich, R. L.; Pollard, W. H.; Omelon, C. R.; Medvigy, David M.; Pffifner, Susan M.; Whyte, L. G.; Onstott, T. C.
The transition of Arctic carbon-rich cryosols into methane (CH₄)-emitting wetlands due to global warming is a rising concern. However, the spatially predominant mineral cryosols and their CH₄ emission potential are poorly understood. Fluxes measured in situ and estimated under laboratory conditions coupled with -omics analysis indicate (1) mineral cryosols in the Canadian high Arctic contain atmospheric CH₄-oxidizing bacteria; (2) the atmospheric CH⁺ uptake flux increases with ground temperature; and, as a result, (3) the atmospheric CH₄ sink strength will increase by a factor of 5-30 as the Arctic warms by 5-15 °C over a century. We demonstrated that acidic mineral cryosols have previously unrecognized potential of negative CH₄ feedback.
Euskirchen, Eugénie S; Goodstein, Eban S; Huntington, Henry P
Recent and expected changes in Arctic sea ice cover, snow cover, and methane emissions from permafrost thaw are likely to result in large positive feedbacks to climate warming. There is little recognition of the significant loss in economic value that the disappearance of Arctic sea ice, snow, and permafrost will impose on humans. Here, we examine how sea ice and snow cover, as well as methane emissions due to changes in permafrost, may potentially change in the future, to year 2100, and how these changes may feed back to influence the climate. Between 2010 and 2100, the annual costs from the extra warming due to a decline in albedo related to losses of sea ice and snow, plus each year's methane emissions, cumulate to a present value cost to society ranging from US$7.5 trillion to US$91.3 trillion. The estimated range reflects uncertainty associated with (1) the extent of warming-driven positive climate feedbacks from the thawing cryosphere and (2) the expected economic damages per metric ton of CO2 equivalents that will be imposed by added warming, which depend, especially, on the choice of discount rate. The economic uncertainty is much larger than the uncertainty in possible future feedback effects. Nonetheless, the frozen Arctic provides immense services to all nations by cooling the earth's temperature: the cryosphere is an air conditioner for the planet. As the Arctic thaws, this critical, climate-stabilizing ecosystem service is being lost. This paper provides a first attempt to monetize the cost of some of those lost services.
Gregory, F. M.; Treitz, P. M.; Scott, N. A.
yet been relatively little detailed work on CO2 flux and NDVI in the high Arctic. Linking these phenomena to vegetation community classification will help clarify the overall carbon sink/source status of the high arctic and facilitate tracking of future climate related changes.
Manno, C.; Pecchiar, I.
With the increased attention on the changing Arctic Region effective science education, outreach and communication need to be higher priorities within the scientific communities. In order to encourage the dissemination of polar research at educational levels foreign high school students and teachers were visiting Tromso University for a week. The project highlights the role of the universities as link between research and outreach. The first aim of this project was to increase awareness of foreign schools on major topics concerning the Arctic issues (from the economic/social to the environmental/climatic point of view). Forty three Italian high school students were involved in the laboratory activities running at the UiT and participated in seminars. Topics of focus were Ocean Acidification, Global Warming and the combined effects with other anthropogenic stressors. During their stay, students interviewed several scientists in order to allow them to edit a "visiting report" and to elaborate all the material collected. Back in Italy they performed an itinerant exhibition (presentation of a short movie, posters, and pictures) in various Italian schools in order to pass on their Arctic education experience. The project highlights the role of University as communicator of "climate related issues" in the international frame of the "new generation" of students.
Schindler, David W; Smol, John P
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.
Anderson, M. R.; Bliss, A. C.; Drobot, S.
The Arctic Ocean is an integral part of the global climate system and an area that is observing record breaking seasonal fluctuations. This study investigates the spring snowmelt onset conditions in the Arctic sea ice cover from 1979 to 2010. Snowmelt onset over Arctic sea ice is defined as the point in time when liquid water appears in the snowpack. Monitoring the timing of snowmelt onset over Arctic sea ice is facilitated by using satellite passive microwave data, because surface microwave emission changes rapidly when liquid water appears in the snowpack, and data acquisitions are relatively unaffected by cloud cover or solar illumination. The Advanced Horizontal Range Algorithm (AHRA) exploits the changes in passive microwave brightness temperatures between 18GHz (19GHz on SSM/I) and 37GHz brightness temperatures to derive snow melt onset dates over Arctic sea ice from 1979-2010. Comparison between AHRA-derived melt onset dates and temperatures from International Arctic Buoy Program/Polar Exchange at the Sea Surface (IABP/POLES) and NCEP/NCAR Reanalysis-2 illustrates melt onset typically occurs when air temperatures near 0oC. Discussion also focuses on how to generate consistency between the different platforms (SMMR and SSM/I) and sensors (SSM/I F8, F11,F13 and F17). This includes how brightness temperatures are obtained and which data formats are used for each platform and sensor. In general, melt onset usually begins in the lower latitudes in the first week of March, and progresses northward towards the central Arctic by the middle of July. The latest melt onset dates are usually observed in the Lincoln Sea, north of Greenland. In comparison with the roughly radial northward melt progression of the annually averaged melt onset, specific years show a high degree of spatial variability. Most years typically have some regions of earlier than average melt, and other regions with later than average melt. The results for the Arctic Ocean region as well as most sub
Wilson, C. J.; Graham, D. E.; Hinzman, L. D.; Hubbard, S. S.; Liang, L.; Norby, R. J.; Riley, W. J.; Rogers, A.; Rowland, J. C.; Thornton, P. E.; Torn, M. S.; Wullschleger, S. D.
A fundamental goal of the Next-Generation Ecosystem Experiments (NGEE-Arctic) project is to improve climate prediction through process understanding and representation of that knowledge in Earth System models. Geomorphological units, including thaw lakes, drained thaw lake basins, and ice-rich polygonal ground provide the organizing framework for our model scaling approach for the coastal plains of the North Slope of Alaska. A comprehensive suite of process studies and observations of hydrology, geomorphology, biogeochemistry, vegetation patterns, and energy exchange and their couplings will be undertaken across nested scales to populate the NGEE hierarchical modeling framework and to achieve a broader goal of optimally informing process representations in a global-scale model. A central focus of this challenge is to advance process understanding and prediction of the evolution of permafrost degradation and its impact on topography and thermal conditions and how these changes control the spatial and temporal availability of water for biogeochemical, ecological, and physical feedbacks to the climate system. Field activities to inform model development is being carried out across a gradient of polygonal ground nested within a drained thaw lake basin age gradient near Barrow, Alaska. Co-analysis of in-situ observations with ground based geophysical and airborne and satellite based remote sensing products from the single polygon to multiple drained lake basin scale is revealing surface-subsurface variability and interactions that influence or control local hydrology, greenhouse gas production, vegetation and the energy balance. We are using a range of data assimilation and fusion techniques to combine spatially extensive data sets developed from multi-scale field data with intensive data being collected from both controlled laboratory experiments using field cores and in-situ thermal, hydrologic, biogeochemical and ecologic observations to improve process understanding
Ulvan, Eva M; Finstad, Anders G; Ugedal, Ola; Berg, Ole Kristian
One of the major challenges in ecological climate change impact science is to untangle the climatic effects on biological interactions and indirect cascading effects through different ecosystems. Here, we test for direct and indirect climatic drivers on competitive impact of Arctic char (Salvelinus alpinus L.) on brown trout (Salmo trutta L.) along a climate gradient in central Scandinavia, spanning from coastal to high-alpine environments. As a measure of competitive impact, trout food consumption was measured using (137)Cs tracer methodology both during the ice-covered and ice-free periods, and contrasted between lakes with or without char coexistence along the climate gradient. Variation in food consumption between lakes was best described by a linear mixed effect model including a three-way interaction between the presence/absence of Arctic char, season and Secchi depth. The latter is proxy for terrestrial dissolved organic carbon run-off, strongly governed by climatic properties of the catchment. The presence of Arctic char had a negative impact on trout food consumption. However, this effect was stronger during ice-cover and in lakes receiving high carbon load from the catchment, whereas no effect of water temperature was evident. In conclusion, the length of the ice-covered period and the export of allochthonous material from the catchment are likely major, but contrasting, climatic drivers of the competitive interaction between two freshwater lake top predators. While future climatic scenarios predict shorter ice-cover duration, they also predict increased carbon run-off. The present study therefore emphasizes the complexity of cascading ecosystem effects in future effects of climate change on freshwater ecosystems.
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.
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.
Jenkyns, Hugh C; Forster, Astrid; Schouten, Stefan; Sinninghe Damsté, Jaap S
To understand the climate dynamics of the warm, equable greenhouse world of the Late Cretaceous period, it is important to determine polar palaeotemperatures. The early palaeoceanographic history of the Arctic Ocean has, however, remained largely unknown, because the sea floor and underlying deposits are usually inaccessible beneath a cover of floating ice. A shallow piston core taken from a drifting ice island in 1970 fortuitously retrieved unconsolidated Upper Cretaceous organic-rich sediment from Alpha ridge, a submarine elevated feature of probable oceanic origin. A lack of carbonate in the sediments from this core has prevented the use of traditional oxygen-isotope palaeothermometry. Here we determine Arctic palaeotemperatures from these Upper Cretaceous deposits using TEX86, a new palaeothermometer that is based on the composition of membrane lipids derived from a ubiquitous component of marine plankton, Crenarchaeota. From these analyses we infer an average sea surface temperature of approximately 15 degrees C for the Arctic Ocean about 70 million years ago. This calibration point implies an Equator-to-pole gradient in sea surface temperatures of approximately 15 degrees C during this interval and, by extrapolation, we suggest that polar waters were generally warmer than 20 degrees C during the middle Cretaceous (approximately 90 million years ago).
Bromwich, David H.; Tzeng, Ren-Yow; Parish, Thomas, R.
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
Semenchuk, Philipp R.; Christiansen, Casper T.; Grogan, Paul; Elberling, Bo; Cooper, Elisabeth J.
Tundra soils store large amounts of carbon (C) that could be released through enhanced ecosystem respiration (ER) as the arctic warms. Over time, this may change the quantity and quality of available soil C pools, which in-turn may feedback and regulate ER responses to climate warming. Therefore, short-term increases in ER rates due to experimental warming may not be sustained over longer periods, as observed in other studies. One important aspect, which is often overlooked, is how climatic changes affecting ER in one season may carry-over and determine ER in following seasons. Using snow fences, we increased snow depth and thereby winter soil temperatures in a high-arctic site in Svalbard (78°N) and a low-arctic site in the Northwest Territories, Canada (64°N), for 5 and 9 years, respectively. Deepened snow enhanced winter ER while having negligible effect on growing-season soil temperatures and soil moisture. Growing-season ER at the high-arctic site was not affected by the snow treatment after 2 years. However, surprisingly, the deepened snow treatments significantly reduced growing-season ER rates after 5 years at the high-arctic site and after 8-9 years at the low-arctic site. We speculate that the reduction in ER rates, that became apparent only after several years of experimental manipulation, may, at least in part, be due to prolonged depletion of labile C substrate as a result of warmer soils over multiple cold seasons. Long-term changes in winter climate may therefore significantly influence annual net C balance not just because of increased wintertime C loss but also because of "legacy" effects on ER rates during the following growing seasons.
Tedesco, M; Mote, T; Fettweis, X; Hanna, E; Jeyaratnam, J; Booth, J F; Datta, R; Briggs, K
Large-scale atmospheric circulation controls the mass and energy balance of the Greenland ice sheet through its impact on radiative budget, runoff and accumulation. Here, using reanalysis data and the outputs of a regional climate model, we show that the persistence of an exceptional atmospheric ridge, centred over the Arctic Ocean, was responsible for a poleward shift of runoff, albedo and surface temperature records over the Greenland during the summer of 2015. New records of monthly mean zonal winds at 500 hPa and of the maximum latitude of ridge peaks of the 5,700±50 m isohypse over the Arctic were associated with the formation and persistency of a cutoff high. The unprecedented (1948-2015) and sustained atmospheric conditions promoted enhanced runoff, increased the surface temperatures and decreased the albedo in northern Greenland, while inhibiting melting in the south, where new melting records were set over the past decade.
Tedesco, M.; Mote, T.; Fettweis, X.; Hanna, E.; Jeyaratnam, J.; Booth, J. F.; Datta, R.; Briggs, K.
Large-scale atmospheric circulation controls the mass and energy balance of the Greenland ice sheet through its impact on radiative budget, runoff and accumulation. Here, using reanalysis data and the outputs of a regional climate model, we show that the persistence of an exceptional atmospheric ridge, centred over the Arctic Ocean, was responsible for a poleward shift of runoff, albedo and surface temperature records over the Greenland during the summer of 2015. New records of monthly mean zonal winds at 500 hPa and of the maximum latitude of ridge peaks of the 5,700+/-50 m isohypse over the Arctic were associated with the formation and persistency of a cutoff high. The unprecedented (1948-2015) and sustained atmospheric conditions promoted enhanced runoff, increased the surface temperatures and decreased the albedo in northern Greenland, while inhibiting melting in the south, where new melting records were set over the past decade.
Tedesco, M.; Mote, T.; Fettweis, X.; Hanna, E.; Jeyaratnam, J.; Booth, J. F.; Datta, R.; Briggs, K.
Large-scale atmospheric circulation controls the mass and energy balance of the Greenland ice sheet through its impact on radiative budget, runoff and accumulation. Here, using reanalysis data and the outputs of a regional climate model, we show that the persistence of an exceptional atmospheric ridge, centred over the Arctic Ocean, was responsible for a poleward shift of runoff, albedo and surface temperature records over the Greenland during the summer of 2015. New records of monthly mean zonal winds at 500 hPa and of the maximum latitude of ridge peaks of the 5,700±50 m isohypse over the Arctic were associated with the formation and persistency of a cutoff high. The unprecedented (1948–2015) and sustained atmospheric conditions promoted enhanced runoff, increased the surface temperatures and decreased the albedo in northern Greenland, while inhibiting melting in the south, where new melting records were set over the past decade. PMID:27277547
Hakkinen, Sirpa; Koblinsky, Chester J. (Technical Monitor)
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).
Thórhallsdóttir, Thóra Ellen
The cool and short growing season that characterizes Arctic climates puts severe constraints on life cycles and reproduction in the Arctic flora. The timing of flowering is particularly critical and may affect both breeding system and reproductive success through the heavy penalties associated with later flowering. An 11-year study of 75 species in the central highland of Iceland showed that the onset of flowering varies greatly among years. The number of species in flower by the first week of July was closely correlated with air temperature (degree days above zero) in the preceding 5 weeks, but no correlations were found with degree days in May or with total degree days in the previous growing season. Time of snowmelt, which has widely been regarded as the environmental event initiating growth and flowering in alpine and arctic tundra, only had a significant effect when two exceptionally cold and late summers were included. The species studied, most of which have a wide distribution in the Arctic, are predicted to respond quickly to warmer spring and early summer temperatures. Accelerated phenologies may alter patterns of resource allocation, have implications for pollinators and pollinator-competition, and could increase the size, species richness and intraspecific genetic diversity of the soil seed bank.
Chapin, F. S.; McGuire, A.D.; Randerson, J.; Pielke, R.; Baldocchi, D.; Hobbie, S.E.; Roulet, Nigel; Eugster, W.; Kasischke, E.; Rastetter, E.B.; Zimov, S.A.; Running, S.W.
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
Nichols, J. E.; Peteet, D. M.
There is a strong climate gradient across the Alaskan Arctic, with important implications for ecology, carbon and nutrient cycling, terrestrial hydrology and permafrost. Hydrogen isotopes of precipitation are important tool for measuring this climate gradient, as it summarizes variability in precipitation, temperature, and other parameters of the ocean-atmosphere system-all important for understanding the rapidly changing climate of the Arctic. We reconstructed D/H ratios of precipitation along with other hydrological and ecological parameters in a series of peatlands throughout the Alaskan Arctic. We reconstruct climate parameters using the hydrogen isotope ratios of leaf wax n-alkanes and paleoecology using distributions of lipid biomarkers and macrofossil identification. By reconstructing D/H ratios at all sites, we are able to compare disparate environments to robustly establish changing precipitation isotope gradients over the Holocene and in the Late Glacial. We investigated four sites in a southeast-northwest transect of the Alaskan arctic, each with stratigraphies covering the Holocene, and two extending into the Late Glacial. We used data from this transect to identify temporal changes in the gradient of precipitation D/H ratios. We also assessed the impact of these changes in the context of Arctic peatland and permafrost carbon accumulation, as these impacts are key to our understanding of the interactions and feedbacks of the terrestrial carbon cycle on recent and future Arctic warming.
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].
Bromwich, D.H.; Tzeng, R.Y. ); Parish, T.R. )
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.
Roof, S.; Werner, A.
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
Birkeland, Siri; Elisabeth Borgen Skjetne, Idunn; Krag Brysting, Anne; Elven, Reidar; Greve Alsos, Inger
Small, isolated, and/or peripheral populations are expected to harbour low levels of genetic variation and may therefore have reduced adaptability to environmental change, including climate warming. In the Arctic, global warming has already caused vegetation change across the region and is acting as a significant stressor on Arctic biodiversity. Many of the rare plants in the Arctic are relicts from early Holocene warm periods, but their ability to benefit from the current warming is dependent on the viability of their populations. We therefore examined Amplified Fragment Length Polymorphism (AFLP) data from regional red listed vascular plant species in the High Arctic archipelago of Svalbard and reference populations from the main distribution area of: 1) Botrychium lunaria, 2) Carex capillaris ssp. fuscidula, 3) Comastoma tenellum, 4) Kobresia simpliciuscula ssp. subholarctica, 5) Ranunculus wilanderi, 6) Sibbaldia procumbens and 7) Tofieldia pusilla In addition, we gathered population size data in Svalbard. The Svalbard populations had low genetic diversity and distinctiveness and few or no private markers compared to populations outside the archipelago. This is similar to observations in other rare species in Svalbard and the genetic depletion may be due to an initial founder effect and/or a genetic bottleneck caused by late Holocene cooling. There seems to be limited gene flow from other areas and the Svalbard populations should therefore be considered as demographically independent management units. Overall, these management units have small and/or few populations and are therefore prone to stochastic events which may further increase vulnerability to inbreeding depression, loss of genetic variation, and reduced evolutionary potential. Our results support theory predicting lower levels of genetic diversity in small, isolated and/or peripheral populations and may be of importance for management of other rare plant species in the Arctic.
Young, K. L.; Abnizova, A.
High Arctic wetlands are lush areas in an otherwise barren landscape. They help to store and replenish water and they serve as significant resting and breeding grounds for migratory birds. In addition, they provide rich grazing grounds for arctic fauna such as muskox and caribou. Arctic wetlands can be small, patchy grounds of wet vegetation or they can encompass large zones characterized by lakes, ponds, wet meadows, and, often times, they are inter-mixed with areas of dry ground. While seasonal snowmelt continues to remain the most critical source of water for recharging ponds, lakes, and meadows in these environments, less is known about the role of lateral inputs of water into low-lying wetlands, namely water flowing into these wetland ecosystems from adjacent hillslopes, which often surround them. This paper will review the different modes of hillslope runoff into both patchy and regional-scale wetlands including late-lying snowbeds, snow-filled creeks, and both small and large (>1st order) streams. It will draw upon field results from four arctic islands (Ellesmere, Cornwallis, Somerset and Bathurst Island) and a research period which spans from the mid'90s until present. Our study will evaluate seasonal and inter-seasonal patterns of snowmelt driven discharge (initiation, duration), timing, and magnitude of peak flows, in addition to stream response to rainfall and dry episodes. The impacts of these lateral water sources for a range of wetlands (ponds, wet meadows) will include an analysis of water level fluctuations (frequency, duration), shrinkage/expansion rates, and water quality. Finally, this study will surmise how these types of lateral hillslope inflows might shift in the future and suggest the impact of these changes on the sustainability of High Arctic wetland terrain.
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
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
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
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.
Moore, S. E.
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.
Arienzo, M. M.; McConnell, J. R.; Chellman, N.; Fritzsche, D.; Kreutz, K. J.; Kipfstuhl, S.; Maselli, O. J.; Nolan, M.; Pasteris, D. R.; Sigl, M.; Steffensen, J. P.
Continental dust is an important component of climate forcing, both because of its interaction with incoming solar and outgoing long wave radiation and because of its impact on albedo when deposited on bright surfaces such as fresh snow. Continental dust may also play an important role in ocean fertilization and carbon sequestration. Because the lifetime of dust aerosol in the atmosphere is only on the order of days to weeks, spatial and temporal variability in concentrations and fluxes is high and understanding of recent and long term changes is limited. Here we present and discuss continuous, high depth resolution measurements of a range of dust proxies in a developing array of Arctic ice cores. Included are traditional proxies such as non-sea-salt (nss) calcium and insoluble particle number and size distribution as well as less traditional proxies such as rare earth elements which together provide important insights into how dust sources and transport may have changed in the past. The array includes a number of new ice core records from Greenland, the North Pacific, and Arctic Russia providing a spatial and temporal record of dust deposition to the Arctic. We compare these detailed dust records with climate and land use proxies to investigate drivers of dustiness in the Arctic during the last millennium.
Juncher Jørgensen, Christian; Christiansen, Jesper; Mariager, Tue; Hugelius, Gustaf
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
Stopa, Justin E.; Ardhuin, Fabrice; Girard-Ardhuin, Fanny
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.
Bitz, C.M.; Battisti, D.S.; Moritz, R.E.; Beesley, J.A.
The low-frequency natural variability of the arctic climate system is modeled using a single-column, energy balance model of the atmosphere, sea ice, and upper-ocean system. Variability in the system is induced by forcing with realistic, random perturbations in the atmospheric energy transport and cloudiness. The model predicts that the volume of perennial sea ice varies predominantly on decadal timescales, while other arctic climate variables vary mostly on intraannual and interannual timescales. The variance of the simulated sea ice volume is most sensitive to perturbations of the atmospheric forcing in late spring, at the onset of melt. The variance of the simulated sea ice volume is most sensitive to perturbations of the atmospheric forcing in the late spring, at the onset of melt. The variance of sea ice volume increases with the mean sea ice thickness and with the number of layers resolved in the sea ice model. This suggests that much of the simulated variance develops when the surface temperature decouples from the sea ice interior during the late spring, when melting snow abruptly exposes the sea ice surface and decreases the surface albedo. The minimum model requirements to simulate the natural variability in the arctic climate are identified. The implications of the low-frequency, natural variability in sea ice volume for detecting a climate change are discussed. Finally, calculations suggest that the variability in the thermodynamic forcing of the polar cap could lead to a freshening in North Atlantic that is comparable to the freshening associated with the Great Salinity Anomaly. 28 refs., 14 figs., 5 tabs.
Godefroit, Pascal; Golovneva, Lina; Shchepetov, Sergei; Garcia, Géraldine; Alekseev, Pavel
A latest Cretaceous (68 to 65 million years ago) vertebrate microfossil assemblage discovered at Kakanaut in northeastern Russia reveals that dinosaurs were still highly diversified in Arctic regions just before the Cretaceous-Tertiary mass extinction event. Dinosaur eggshell fragments, belonging to hadrosaurids and non-avian theropods, indicate that at least several latest Cretaceous dinosaur taxa could reproduce in polar region and were probably year-round residents of high latitudes. Palaeobotanical data suggest that these polar dinosaurs lived in a temperate climate (mean annual temperature about 10 degrees C), but the climate was apparently too cold for amphibians and ectothermic reptiles. The high diversity of Late Maastrichtian dinosaurs in high latitudes, where ectotherms are absent, strongly questions hypotheses according to which dinosaur extinction was a result of temperature decline, caused or not by the Chicxulub impact.
Godefroit, Pascal; Golovneva, Lina; Shchepetov, Sergei; Garcia, Géraldine; Alekseev, Pavel
A latest Cretaceous (68 to 65 million years ago) vertebrate microfossil assemblage discovered at Kakanaut in northeastern Russia reveals that dinosaurs were still highly diversified in Arctic regions just before the Cretaceous-Tertiary mass extinction event. Dinosaur eggshell fragments, belonging to hadrosaurids and non-avian theropods, indicate that at least several latest Cretaceous dinosaur taxa could reproduce in polar region and were probably year-round residents of high latitudes. Palaeobotanical data suggest that these polar dinosaurs lived in a temperate climate (mean annual temperature about 10°C), but the climate was apparently too cold for amphibians and ectothermic reptiles. The high diversity of Late Maastrichtian dinosaurs in high latitudes, where ectotherms are absent, strongly questions hypotheses according to which dinosaur extinction was a result of temperature decline, caused or not by the Chicxulub impact.
Stendel, M.; Christensen, J. H.
Simulations with global climate models (GCMs) clearly indicate that major climate changes for the Arctic can be expected during the 21st century. Already now, there are substantial changes in sea-ice extent and thickness and a considerable increase in air temperature in several regions. Contemporary GCMs are unable to give a realistic representation of the climate and climate change in regions with steep orography, due to their coarse resolution. But even relatively high resolution regional climate models (RCMs) fail in this respect. We have therefore conducted a transient simulation with the newest version of the HIRHAM RCM, covering the period 1958-2001 over a region in northeast European Russia, including the Ural Mountains, with the unprecedented horizontal resolution of 4 km. For this simulation, a double downscaling procedure was applied. Average and extreme values will be discussed, and a comparison of subsurface temperatures to a set of observations from the region will be presented.
de Vernal, A.; Hillaire-Marcel, C.; Rochon, A.
The reconstruction of sea-surface conditions including sea ice cover was undertaken based on about 20 marine sediment cores collected in the Arctic Ocean and subarctic seas. The approach has been standardized and mostly relies on the modern analogue technique applied to dinoflagellate cyst assemblages, which permit simultaneous estimates of sea ice cover, summer sea-surface temperature and salinity. The results show some regionalism in both trends, amplitude and overall variability. In general, changes of small amplitude are recorded in the Canadian Arctic whereas a slight cooling trend with an increasing sea ice cover characterizes the Northern Baffin Bay and Fram Strait areas from mid to late Holocene. In contrast, the Chukchi Sea records show large amplitude variations with millennial pacing making difficult to define any trend. The Chukchi Sea data indicate reduced sea ice and warmer conditions during the mid-Holocene, notably around 6.5 and 3.5 ka, and also point to important variations during the last millennium. The overall results suggest a higher variability thus sensitivity to climate change, in the Chukchi Sea area than in the Eastern parts of the Arctic and subarctic regions, which are largely influenced by northern branches of the North Atlantic Drift. The climate sensitivity of the Chukchi Sea area may be related to the proximity of the Pacific gateway. Strong linkages between sea-surface conditions, sea ice cover and export rate seem tightly linked there with large scale atmospheric synopses in the North Pacific and possibly the tropical Pacific. The apparent consistency of the Mount Logan record (Fisher et al., the Holocene 2008) with those of the Chukchi Sea (de Vernal et al., Quat. Sci. Rev. 2013) tends to support the hypothesis of a strong influence of North Pacific atmospheric teleconnections on sea-surface conditions in the Western Arctic.
Anisimov, O. A.; Kokorev, V.
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
Behrens, L.; Martin, T.; Semenov, V.; Latif, M.
Changes due to global warming are particularly obvious in the Arctic. The IPCC-Report of 2007 shows, that the warming in the Arctic is twice as strong as the mean global warming. We investigate changes in the Arctic sea ice in a set of 19 CMIP-3 Models with a focus on the entire Arctic as well as for different regions. In all regions, the models predict a reduction in sea ice extent, sea ice thickness and sea ice volume during the period 1900-2100. Furthermore, changes are obvious in the amplitude and phase of the seasonal cycle. The phase of the seasonal maximum ice extent occurs later in the year. However, this effect is not visible for the sea ice thickness and the sea ice volume. For the sea ice extent, the amplitude of the seasonal cycle increases in nearly all regions, because of the strongest sea ice extent decrease in September. In the entire Arctic, the amplitude of sea ice volume shows a damping because of the reduction of sea ice volume is stronger in March than in September. All model projections show a strong discrepancies in different regions. However, a multi model mean estimates are comparable with observational data for the entire Arctic. In smaller regions, the differences between the multi model mean and the observational data are large. The local sensitivity against global warming has been investigated. Here, we analyze the difference between different periods for the sea ice extent and the surface air temperature. A seasonal dependence of the sensitivity has been found in all models. The differences between the model predictions are smaller in winter in comparison to summer season. However, in the regions Barents Sea and Greenland-Iceland-Norwegian Sea the models sensitivities are very different in all season.
Parkinson, Claire L.; Zukor, Dorothy J. (Technical Monitor)
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.
Sedlar, Joseph; Tjernström, Michael
While the atmospheric greenhouse effect always results in a warming at the surface, outgoing longwave radiation (OLR) to space always represents a cooling. During events of heat and moisture advection into the Arctic, increases in tropospheric temperature and moisture impact clouds, in turn impacting longwave (LW) radiation. State-of-the-art satellite measurements and atmospheric reanalysis consistently reveal an enhancement of summer Arctic monthly OLR cooling ranging 1.5-4 W m-2 during months with anomalously high thermodynamic advection. This cooling anomaly is found to be of the same magnitude or slightly larger than associated downwelling LW surface warming anomalies. We identify a relationship between large-scale circulation variability and changing cloud properties permitting LW radiation at both the surface and top of the atmosphere to respond to variability in atmospheric thermodynamics. Driven by anomalous advection of warm air, the corresponding enhanced OLR cooling signal on monthly time scales represents an important buffer to regional Arctic warming.
Olsen, S. M.; Hansen, B.; Østerhus, S.; Quadfasel, D.; Valdimarsson, H.
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
Lozhkin, A. V.; Anderson, P. M.; Minyuk, P. S.; Nedorubova, E. Yu.; Goryachev, N. A.
The palynological investigations of sediments of the crater of El'gygytgyn Lake (67°30' N, 172°05' E), which provided a continuous record of interglacial and glacial events in Polar Chukotka, revealed significant climate warming corresponding to Marine Isotope Stage 31 (MIS 31) lasting from 1.062 to 1.081Ma ago. Its upper limit is placed within the Jaramillo paleomagnetic episode (0.99-1.07 Ma) registered in the sedimentary section of the lake. During MIS 31, the vegetation community was dominated by Betula- Alnus forests with subordinate Larix trees. These forests included also coniferous ( Picea, Pinus) and broad-leaved trees and shrubs ( Quercus, Carpinus, Corylus). The interglacial of MIS 31 was characterized by the warmest climate for the entire Quaternary Period. The warming episode established in the continuous record of the section of El'gygytgyn Lake implies relations between climatic events in the Arctic and Antarctic regions.
Octaviani, Mega; Stemmler, Irene; Lammel, Gerhard; Graf, Hans F
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.
Cronin, Heather A.; Cohen, Jonathan H.; Berge, Jørgen; Johnsen, Geir; Moline, Mark A.
Bioluminescence commonly influences pelagic trophic interactions at mesopelagic depths. Here we characterize a vertical gradient in structure of a generally low species diversity bioluminescent community at shallower epipelagic depths during the polar night period in a high Arctic fjord with in situ bathyphotometric sampling. Bioluminescence potential of the community increased with depth to a peak at 80 m. Community composition changed over this range, with an ecotone at 20–40 m where a dinoflagellate-dominated community transitioned to dominance by the copepod Metridia longa. Coincident at this depth was bioluminescence exceeding atmospheric light in the ambient pelagic photon budget, which we term the bioluminescence compensation depth. Collectively, we show a winter bioluminescent community in the high Arctic with vertical structure linked to attenuation of atmospheric light, which has the potential to influence pelagic ecology during the light-limited polar night. PMID:27805028
Cronin, Heather A; Cohen, Jonathan H; Berge, Jørgen; Johnsen, Geir; Moline, Mark A
Bioluminescence commonly influences pelagic trophic interactions at mesopelagic depths. Here we characterize a vertical gradient in structure of a generally low species diversity bioluminescent community at shallower epipelagic depths during the polar night period in a high Arctic fjord with in situ bathyphotometric sampling. Bioluminescence potential of the community increased with depth to a peak at 80 m. Community composition changed over this range, with an ecotone at 20-40 m where a dinoflagellate-dominated community transitioned to dominance by the copepod Metridia longa. Coincident at this depth was bioluminescence exceeding atmospheric light in the ambient pelagic photon budget, which we term the bioluminescence compensation depth. Collectively, we show a winter bioluminescent community in the high Arctic with vertical structure linked to attenuation of atmospheric light, which has the potential to influence pelagic ecology during the light-limited polar night.
Cronin, Heather A.; Cohen, Jonathan H.; Berge, Jørgen; Johnsen, Geir; Moline, Mark A.
Bioluminescence commonly influences pelagic trophic interactions at mesopelagic depths. Here we characterize a vertical gradient in structure of a generally low species diversity bioluminescent community at shallower epipelagic depths during the polar night period in a high Arctic fjord with in situ bathyphotometric sampling. Bioluminescence potential of the community increased with depth to a peak at 80 m. Community composition changed over this range, with an ecotone at 20–40 m where a dinoflagellate-dominated community transitioned to dominance by the copepod Metridia longa. Coincident at this depth was bioluminescence exceeding atmospheric light in the ambient pelagic photon budget, which we term the bioluminescence compensation depth. Collectively, we show a winter bioluminescent community in the high Arctic with vertical structure linked to attenuation of atmospheric light, which has the potential to influence pelagic ecology during the light-limited polar night.
Friedman, C. L.; Selin, N. E.
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
Juncher Jørgensen, Christian; Lund Johansen, Katrine Maria; Westergaard-Nielsen, Andreas; Elberling, Bo
Arctic tundra soils serve as potentially important but poorly understood sinks of atmospheric methane (CH4), a powerful greenhouse gas. Numerical simulations project a net increase in methane consumption in soils in high northern latitudes as a consequence of warming in the past few decades. Advances have been made in quantifying hotspots of methane emissions in Arctic wetlands, but the drivers, magnitude, timing and location of methane consumption rates in High Arctic ecosystems are unclear. Here, we present measurements of rates of methane consumption in different vegetation types within the Zackenberg Valley in northeast Greenland over a full growing season. Field measurements show methane uptake in all non-water-saturated landforms studied, with seasonal averages of - 8.3 +/- 3.7 μmol CH4 m-2 h-1 in dry tundra and - 3.1 +/- 1.6 μmol CH4 m-2 h-1 in moist tundra. The fluxes were sensitive to temperature, with methane uptake increasing with increasing temperatures. We extrapolate our measurements and published measurements from wetlands with the help of remote-sensing land-cover classification using nine Landsat scenes. We conclude that the ice-free area of northeast Greenland acts as a net sink of atmospheric methane, and suggest that this sink will probably be enhanced under future warmer climatic conditions.
Zwolicki, Adrian; Zmudczyńska-Skarbek, Katarzyna; Richard, Pierre; Stempniewicz, Lech
We studied the relative importance of several environmental factors for tundra plant communities in five locations across Svalbard (High Arctic) that differed in geographical location, oceanographic and climatic influence, and soil characteristics. The amount of marine-derived nitrogen in the soil supplied by seabirds was locally the most important of the studied environmental factors influencing the tundra plant community. We found a strong positive correlation between δ15N isotopic values and total N content in the soil, confirming the fundamental role of marine-derived matter to the generally nutrient-poor Arctic tundra ecosystem. We also recorded a strong correlation between the δ15N values of soil and of the tissues of vascular plants and mosses, but not of lichens. The relationship between soil δ15N values and vascular plant cover was linear. In the case of mosses, the percentage ground cover reached maximum around a soil δ 15N value of 8‰, as did plant community diversity. This soil δ15N value clearly separated the occurrence of plants with low nitrogen tolerance (e.g. Salix polaris) from those predominating on high N content soils (e.g. Cerastium arcticum, Poa alpina). Large colonies of planktivorous little auks have a great influence on Arctic tundra vegetation, either through enhancing plant abundance or in shaping plant community composition at a local scale. PMID:27149113
Zwolicki, Adrian; Zmudczyńska-Skarbek, Katarzyna; Richard, Pierre; Stempniewicz, Lech
We studied the relative importance of several environmental factors for tundra plant communities in five locations across Svalbard (High Arctic) that differed in geographical location, oceanographic and climatic influence, and soil characteristics. The amount of marine-derived nitrogen in the soil supplied by seabirds was locally the most important of the studied environmental factors influencing the tundra plant community. We found a strong positive correlation between δ15N isotopic values and total N content in the soil, confirming the fundamental role of marine-derived matter to the generally nutrient-poor Arctic tundra ecosystem. We also recorded a strong correlation between the δ15N values of soil and of the tissues of vascular plants and mosses, but not of lichens. The relationship between soil δ15N values and vascular plant cover was linear. In the case of mosses, the percentage ground cover reached maximum around a soil δ 15N value of 8‰, as did plant community diversity. This soil δ15N value clearly separated the occurrence of plants with low nitrogen tolerance (e.g. Salix polaris) from those predominating on high N content soils (e.g. Cerastium arcticum, Poa alpina). Large colonies of planktivorous little auks have a great influence on Arctic tundra vegetation, either through enhancing plant abundance or in shaping plant community composition at a local scale.
Glantz, Paul; Bourassa, Adam; Herber, Andreas; Iversen, Trond; Karlsson, Johannes; Kirkevåg, Alf; Maturilli, Marion; Seland, Øyvind; Stebel, Kerstin; Struthers, Hamish; Tesche, Matthias; Thomason, Larry
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
Popovicheva, Olga Borsovna; Evangeliou, Nikolaos; Eleftheriadis, Konstantinos; Kalogridis, Athina Cerise; Movchan, Vadim Vadimovich; Sitnikov, Nikolay; Eckhardt, Sabine; Makshtas, Alexander; Stohl, Andreas
Understanding the role of short-lived climate forcers like black carbon (BC) at high northern latitudes in climate change is hampered by the scarcity of surface observations in the Russian Arctic. In this study, highly time resolved Equivalent BC (EBC) measurements during a ship campaign in the White, Barents and Kara Seas in October 2015 are presented. The measured EBC concentrations are compared with BC concentrations simulated with a Lagrangian particle dispersion model coupled with a recently completed global emission inventory to quantify the origin of the Arctic BC. EBC showed increased values (100-400 ng m-3) in the Kara Strait, Kara Sea, and Kola Peninsula, and an extremely high concentration (1000 ng m-3) in the White Sea. Assessment of BC origin throughout the expedition showed that gas flaring emissions from the Yamal/Khanty-Mansiysk and Nenets/Komi regions contributed the most when the ship was close to the Kara Strait, north of 70˚N. Near Arkhangelsk (White Sea), biomass burning in mid-latitudes, surface transportation, and residential and commercial combustion from Central and Eastern Europe were found to be important BC sources. The model reproduced observed EBC concentrations efficiently, building credibility in the emission inventory for BC emissions at high northern latitudes.
Kaufman, D. S.; McKay, N.
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
Schartup, Amina T.; Balcom, Prentiss H.; Soerensen, Anne L.; Gosnell, Kathleen J.; Calder, Ryan S. D.; Mason, Robert P.; Sunderland, Elsie M.
Elevated levels of neurotoxic methylmercury in Arctic food-webs pose health risks for indigenous populations that consume large quantities of marine mammals and fish. Estuaries provide critical hunting and fishing territory for these populations, and, until recently, benthic sediment was thought to be the main methylmercury source for coastal fish. New hydroelectric developments are being proposed in many northern ecosystems, and the ecological impacts of this industry relative to accelerating climate changes are poorly characterized. Here we evaluate the competing impacts of climate-driven changes in northern ecosystems and reservoir flooding on methylmercury production and bioaccumulation through a case study of a stratified sub-Arctic estuarine fjord in Labrador, Canada. Methylmercury bioaccumulation in zooplankton is higher than in midlatitude ecosystems. Direct measurements and modeling show that currently the largest methylmercury source is production in oxic surface seawater. Water-column methylation is highest in stratified surface waters near the river mouth because of the stimulating effects of terrestrial organic matter on methylating microbes. We attribute enhanced biomagnification in plankton to a thin layer of marine snow widely observed in stratified systems that concentrates microbial methylation and multiple trophic levels of zooplankton in a vertically restricted zone. Large freshwater inputs and the extensive Arctic Ocean continental shelf mean these processes are likely widespread and will be enhanced by future increases in water-column stratification, exacerbating high biological methylmercury concentrations. Soil flooding experiments indicate that near-term changes expected from reservoir creation will increase methylmercury inputs to the estuary by 25–200%, overwhelming climate-driven changes over the next decade. PMID:26351688
Schartup, Amina T; Balcom, Prentiss H; Soerensen, Anne L; Gosnell, Kathleen J; Calder, Ryan S D; Mason, Robert P; Sunderland, Elsie M
Elevated levels of neurotoxic methylmercury in Arctic food-webs pose health risks for indigenous populations that consume large quantities of marine mammals and fish. Estuaries provide critical hunting and fishing territory for these populations, and, until recently, benthic sediment was thought to be the main methylmercury source for coastal fish. New hydroelectric developments are being proposed in many northern ecosystems, and the ecological impacts of this industry relative to accelerating climate changes are poorly characterized. Here we evaluate the competing impacts of climate-driven changes in northern ecosystems and reservoir flooding on methylmercury production and bioaccumulation through a case study of a stratified sub-Arctic estuarine fjord in Labrador, Canada. Methylmercury bioaccumulation in zooplankton is higher than in midlatitude ecosystems. Direct measurements and modeling show that currently the largest methylmercury source is production in oxic surface seawater. Water-column methylation is highest in stratified surface waters near the river mouth because of the stimulating effects of terrestrial organic matter on methylating microbes. We attribute enhanced biomagnification in plankton to a thin layer of marine snow widely observed in stratified systems that concentrates microbial methylation and multiple trophic levels of zooplankton in a vertically restricted zone. Large freshwater inputs and the extensive Arctic Ocean continental shelf mean these processes are likely widespread and will be enhanced by future increases in water-column stratification, exacerbating high biological methylmercury concentrations. Soil flooding experiments indicate that near-term changes expected from reservoir creation will increase methylmercury inputs to the estuary by 25-200%, overwhelming climate-driven changes over the next decade.
Lindwall, Frida; Faubert, Patrick; Rinnan, Riikka
Many hours of sunlight in the midnight sun period suggest that significant amounts of biogenic volatile organic compounds (BVOCs) may be released from arctic ecosystems during night-time. However, the emissions from these ecosystems are rarely studied and limited to point measurements during daytime. We measured BVOC emissions during 24-hour periods in the field using a push-pull chamber technique and collection of volatiles in adsorbent cartridges followed by analysis with gas chromatography- mass spectrometry. Five different arctic vegetation communities were examined: high arctic heaths dominated by Salix arctica and Cassiope tetragona, low arctic heaths dominated by Salix glauca and Betula nana and a subarctic peatland dominated by the moss Warnstorfia exannulata and the sedge Eriophorum russeolum. We also addressed how climate warming affects the 24-hour emission and how the daytime emissions respond to sudden darkness. The emissions from the high arctic sites were lowest and had a strong diel variation with almost no emissions during night-time. The low arctic sites as well as the subarctic site had a more stable release of BVOCs during the 24-hour period with night-time emissions in the same range as those during the day. These results warn against overlooking the night period when considering arctic emissions. During the day, the quantity of BVOCs and the number of different compounds emitted was higher under ambient light than in darkness. The monoterpenes α-fenchene, α -phellandrene, 3-carene and α-terpinene as well as isoprene were absent in dark measurements during the day. Warming by open top chambers increased the emission rates both in the high and low arctic sites, forewarning higher emissions in a future warmer climate in the Arctic. PMID:25897519
Lindwall, Frida; Faubert, Patrick; Rinnan, Riikka
Many hours of sunlight in the midnight sun period suggest that significant amounts of biogenic volatile organic compounds (BVOCs) may be released from arctic ecosystems during night-time. However, the emissions from these ecosystems are rarely studied and limited to point measurements during daytime. We measured BVOC emissions during 24-hour periods in the field using a push-pull chamber technique and collection of volatiles in adsorbent cartridges followed by analysis with gas chromatography-mass spectrometry. Five different arctic vegetation communities were examined: high arctic heaths dominated by Salix arctica and Cassiope tetragona, low arctic heaths dominated by Salix glauca and Betula nana and a subarctic peatland dominated by the moss Warnstorfia exannulata and the sedge Eriophorum russeolum. We also addressed how climate warming affects the 24-hour emission and how the daytime emissions respond to sudden darkness. The emissions from the high arctic sites were lowest and had a strong diel variation with almost no emissions during night-time. The low arctic sites as well as the subarctic site had a more stable release of BVOCs during the 24-hour period with night-time emissions in the same range as those during the day. These results warn against overlooking the night period when considering arctic emissions. During the day, the quantity of BVOCs and the number of different compounds emitted was higher under ambient light than in darkness. The monoterpenes α-fenchene, α-phellandrene, 3-carene and α-terpinene as well as isoprene were absent in dark measurements during the day. Warming by open top chambers increased the emission rates both in the high and low arctic sites, forewarning higher emissions in a future warmer climate in the Arctic.
Bokhorst, Stef; Phoenix, Gareth K; Berg, Matty P; Callaghan, Terry V; Kirby-Lambert, Christopher; Bjerke, Jarle W
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
Selbmann, A. K.; Natali, S.
The arctic is warming at twice the rate of the rest of the planet, with the greatest warming occurring during the winter months. Despite the cold temperatures during the winter, microbial activity continues and leads to a release of soil carbon during a criticial period when plant uptake has ceased. Due to the warming climate, huge pools of carbon stored in permafrost soils are expected to be released to the atmosphere. To identify the annual carbon balance of arctic ecosystems and potential impacts caused by a rise in temperatures, understanding the magnitude of winter respiration is essential. In order to refine current and future estimates of carbon loss from permafrost ecosystems, we conducted a pan-arctic synthesis of winter respiration from northern high latitude regions. We examined differences in cumulative winter respiration among permafrost zones, biomes, ecosystem types, and effects of measurement method on winter respiration estimates. We also examined effect of air temperature and precipitation (Worldclim database) on rates of winter respiration. The database contained 169 measurement points from 46 study sites located throughout the permafrost zones. We found that 21.6 % of annual respiration is happening during non-growing season, which can shift ecosystems from annual sinks during the growing season to net sources of carbon on an annual basis. Across studies, the average carbon loss during the winter was 66 g CO2-C. There was a strong relationship between mean annual air temperature and winter respiration, and lower respiration in continuous compared to discontinuous permafrost zones and northern areas without permafrost. The present results clarify the contribution of winter respiration to annual carbon balance and show the sensitivity of carbon release to rising temperatures in northern high latitudes. These results suggest that permafrost degradation and increased temperature will lead to a higher release of carbon from the Arctic in wintertime
Miccadei, Enrico; Piacentini, Tommaso; Casacchia, Ruggero; Sparapani, Roberto
The geomorphological effects of glacial retreat, rapidly changing Arctic environments and consequent local temporary permafrost melting are several types of glacial and periglacial landforms (pingos, solifluction, drumlins, etc.) but also debris and rock falls, alluvial fan and glacial outwash development and scarp/slopes retreat and evolution. In this work we have realized a geomorphologic map of rockfalls, landslides, alluvial fans and the slopes and scarps of steep mountainsides in the Ny Ålesund area (Svalbard Island, Norway) focused on the analysis of rock falls as geomorphological effects of glacier retreat, permafrost degradation and higher temperatures on slope processes. The investigation is based on geological and geomorphological field survey, and remote sensing and aerial photo interpretation, The Ny Ålesund area landscape is characterized by rugged non-vegetated mountains only partially covered by glaciers, with steep flanks and rock scarps; the scarps are formed by different types of rocks (intrusive and effusive igneous rocks, marine sedimentary rocks); this landscape is highly affected by debris and rock falls (from scarps and slopes) forming wide talus slopes and by alluvial fan and fluvial outwash (from glaciers), which make the surface sedimentary cover of the island together with rock glaciers and moraine deposits and locally fluvial deposits. The work is focused on the comprehension of the role of different factors in inducing rock falls, alluvial fans, slope/scarps evolution in high geomorphological sensitivity environments (i.e. glacial, periglacial or mountain) including: orography, lithology, rock fracturation, morphostructural setting, meteorological context. The conclusions focus on the possible geomorphological hazards affecting the Ny Ålesund area.
Gauthier, Gilles; Bêty, Joël; Cadieux, Marie-Christine; Legagneux, Pierre; Doiron, Madeleine; Chevallier, Clément; Lai, Sandra; Tarroux, Arnaud; Berteaux, Dominique
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.
Gauthier, Gilles; Bêty, Joël; Cadieux, Marie-Christine; Legagneux, Pierre; Doiron, Madeleine; Chevallier, Clément; Lai, Sandra; Tarroux, Arnaud; Berteaux, Dominique
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
Emmerton, C. A.
High Arctic landscapes are expansive and changing rapidly. However our understanding of their functional responses and potential to mitigate or enhance anthropogenic climate change is limited by few measurements. We collected eddy covariance measurements to quantify the net ecosystem exchange (NEE) of CO2 with polar semidesert and meadow wetland landscapes at the highest-latitude location measured to date (82°N). We coupled these rare data with ground and satellite vegetation production measurements (Normalized Difference Vegetation Index; NDVI) to evaluate the effectiveness of upscaling local to regional NEE. During the growing season, the dry polar semidesert landscape was a near zero sink of atmospheric CO2 (NEE: -0.3±13.5 g C m-2). A nearby meadow wetland accumulated over two magnitudes more carbon (NEE: -79.3±20.0 g C m-2) than the polar semidesert landscape, and was similar to meadow wetland NEE at much more southern latitudes. Polar semidesert NEE was most influenced by moisture, with wetter surface soils resulting in greater soil respiration and CO2 emissions. At the meadow wetland, soil heating enhanced plant growth, which in turn increased CO2 uptake. Our upscaling assessment found that polar semidesert NDVI measured on site was low (mean: 0.120-0.157) and similar to satellite measurements (mean: 0.155-0.163). However, weak plant growth resulted in poor satellite NDVI-NEE relationships and created challenges for remotely-detecting changes in the cycling of carbon on the polar semidesert landscape. The meadow wetland appeared more suitable to assess plant production and NEE via remote-sensing, however high Arctic wetland extent is constrained by topography to small areas that may be difficult to resolve with large satellite pixels. We predict that until summer precipitation and humidity increases substantially, climate-related changes of dry high Arctic landscapes may be restricted by poor soil moisture retention, and therefore have some inertia against
Zhang, Tao; Wang, Neng-Fei; Zhang, Yu-Qin; Liu, Hong-Yu; Yu, Li-Yan
We assessed the diversity and distribution of fungi in 13 water samples collected from four aquatic environments (stream, pond, melting ice water, and estuary) in the Ny-Ålesund Region, Svalbard (High Arctic) using 454 pyrosequencing with fungi-specific primers targeting the internal transcribed spacer (ITS) region of the ribosomal rRNA gene. Aquatic fungal communities in this region showed high diversity, with a total of 43,061 reads belonging to 641 operational taxonomic units (OTUs) being found. Of these OTUs, 200 belonged to Ascomycota, 196 to Chytridiomycota, 120 to Basidiomycota, 13 to Glomeromycota, and 10 to early diverging fungal lineages (traditional Zygomycota), whereas 102 belonged to unknown fungi. The major orders were Helotiales, Eurotiales, and Pleosporales in Ascomycota; Chytridiales and Rhizophydiales in Chytridiomycota; and Leucosporidiales and Sporidiobolales in Basidiomycota. The common fungal genera Penicillium, Rhodotorula, Epicoccum, Glaciozyma, Holtermanniella, Betamyces, and Phoma were identified. Interestingly, the four aquatic environments in this region harbored different aquatic fungal communities. Salinity, conductivity, and temperature were important factors in determining the aquatic fungal diversity and community composition. The results suggest the presence of diverse fungal communities and a considerable number of potentially novel fungal species in Arctic aquatic environments, which can provide reliable data for studying the ecological and evolutionary responses of fungi to climate change in the Arctic ecosystem.
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.
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
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
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.
St Pierre, K A; Chétélat, J; Yumvihoze, E; Poulain, A J
Monomethylmercury (MMHg) is a neurotoxin of concern in the Canadian Arctic due to its tendency to bioaccumulate and the importance of fish and wildlife in the Inuit diet. In lakes and wetlands, microbial sediment communities are integral to the cycling of MMHg; however, the role of Arctic marine sediments is poorly understood. With projected warming, the effect of temperature on the production and degradation of MMHg in Arctic environments also remains unclear. We examined MMHg dynamics across a temperature gradient (4, 12, 24 °C) in marine sediments collected in Allen Bay, Nunavut. Slurries were spiked with stable mercury isotopes and amended with specific microbial stimulants and inhibitors, and subsampled over 12 days. Maximal methylation and demethylation potentials were low, ranging from below detection to 1.13 pmol g(-1) h(-1) and 0.02 pmol g(-1) h(-1), respectively, suggesting that sediments are likely not an important source of MMHg to overlying water. Our results suggest that warming may result in an increase in Hg methylation - controlled by temperature-dependent sulfate reduction, without a compensatory increase in demethylation. This study highlights the need for further research into the role of high Arctic marine sediments and climate on the Arctic marine MMHg budget.
Stempniewicz, Lech; Błachowiak-Samołyk, Katarzyna; Węsławski, Jan M.
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
Lawrence, David M.; Swenson, Sean C.
Deciduous shrub abundance is increasing across the Arctic in response to climatic warming. In a recent field manipulation experiment in which shrubs were removed from a plot and compared to a control plot with shrubs, Blok et al (2010 Glob. Change Biol. 16 1296-305) found that shrubs protect the ground through shading, resulting in a ~ 9% shallower active layer thickness (ALT) under shrubs compared to grassy-tundra, which led them to argue that continued Arctic shrub expansion could mitigate future permafrost thaw. We utilize the Community Land Model (CLM4) coupled to the Community Atmosphere Model (CAM4) to evaluate this hypothesis. CLM4 simulates shallower ALT (~- 11 cm) under shrubs, consistent with the field manipulation study. However, in an idealized pan-Arctic + 20% shrub area experiment, atmospheric heating, driven mainly by surface albedo changes related to protrusion of shrub stems above the spring snowpack, leads to soil warming and deeper ALT (~+ 10 cm). Therefore, if climate feedbacks are considered, shrub expansion may actually increase rather than decrease permafrost vulnerability. When we account for blowing-snow redistribution from grassy-tundra to shrubs, shifts in snowpack distribution in low versus high shrub area simulations counter the climate warming impact, resulting in a grid cell mean ALT that is unchanged. These results reinforce the need to consider vegetation dynamics and blowing-snow processes in the permafrost thaw model projections.
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.
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
Yu, Qin; Epstein, Howard; Engstrom, Ryan; Walker, Donald
Satellite remote sensing data have indicated a general 'greening' trend in the arctic tundra biome. However, the observed changes based on remote sensing are the result of multiple environmental drivers, and the effects of individual controls such as warming, herbivory, and other disturbances on changes in vegetation biomass, community structure, and ecosystem function remain unclear. We apply ArcVeg, an arctic tundra vegetation dynamics model, to estimate potential changes in vegetation biomass and net primary production (NPP) at the plant community and functional type levels. ArcVeg is driven by soil nitrogen output from the Terrestrial Ecosystem Model, existing densities of Rangifer populations, and projected summer temperature changes by the NCAR CCSM4.0 general circulation model across the Arctic. We quantified the changes in aboveground biomass and NPP resulting from (i) observed herbivory only; (ii) projected climate change only; and (iii) coupled effects of projected climate change and herbivory. We evaluated model outputs of the absolute and relative differences in biomass and NPP by country, bioclimate subzone, and floristic province. Estimated potential biomass increases resulting from temperature increase only are approximately 5% greater than the biomass modeled due to coupled warming and herbivory. Such potential increases are greater in areas currently occupied by large or dense Rangifer herds such as the Nenets-occupied regions in Russia (27% greater vegetation increase without herbivores). In addition, herbivory modulates shifts in plant community structure caused by warming. Plant functional types such as shrubs and mosses were affected to a greater degree than other functional types by either warming or herbivory or coupled effects of the two.
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.
Irvine-Fynn, T. D.; Hodson, A. J.; Bridge, J. W.; Langford, H.; Anesio, A.; Ohlanders, N.; Newton, S.
There has been a growing awareness of the significance of biologically active dust (cryoconite) on the energy balance of, and nutrient cycling at glacier surfaces. Moreover, researchers have estimated the mass of biological material released from glacier ice to downstream environments and ecosystems, including the melt-out of cells from emergent ice in the ablation area. However, the processes, rates and mechanisms of cryoconite mobility and transport have not been fully explored. For many smaller valley glaciers in the High-Arctic, the climate dictates only a thin (~ 1m) layer of ice at the glacier surface is at the melting point during the summer months. This surface ice is commonly characterized by an increased porosity in response to incident energy and hydraulic conditions, and has been termed the “weathering crust”. The presence of cryoconite, with its higher radiation absorption, exacerbates the weathering crust development. Thus, crucially, the transport of cryoconite is not confined to simply a ‘smooth’ ice surface, but rather also includes mobility in the near-surface ice matrix. Here, we present initial results from investigations of cryoconite transport at Midtre Lovénbreen and Longyearbreen, two north-facing valley glaciers in Svalbard (Norway). Using time-lapse imagery, we explore the transport rates of cryoconite on a glacier surface and consider the associations between mobility and meteorological conditions. Results suggest some disparity between micro-, local- and plot-scale observations of cryoconite transport: the differences imply controlling influences of cryoconite volume, ice surface topography and ice structure. While to examine the relative volumes of cryoconite exported from the glacier surface by supraglacial streams we employ flow cytometry, using SYBR-Green-II staining to identify the biological component of the suspended load. Preliminary comparisons between shallow (1m) ice cores and in-stream concentrations suggest
Polk, J.; North, L. A.; Strenecky, B.
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.
Evengard, Birgitta; Berner, Jim; Brubaker, Michael; Mulvad, Gert; Revich, Boris
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.
Chevallier, Matthieu; Guémas, Virginie; Salas y Mélia, David; Doblas-Reyes, Francisco
The predictive capabilities of two state-of-the-art coupled atmosphere-ocean global climate models (CNRM-CM5.1 and EC-Earth v2.3) in seasonal forecasting of the Arctic sea ice will be presented with a focus on regional skill. 5-month hindcasts of September sea ice area in the Arctic peripherial seas (Barents-Kara seas, Laptev-East Siberian seas, Chukchi sea and Beaufort sea) and March sea ice area in the marginal ice zones (Barents, Greenland, Labrador, Bering and Okhotsk sea) have been produced over the period 1990-2009. Systems mainly differ with respect to the initialization strategy, the ensemble generation techniques and the sea ice components. Predictive skill, assessed in terms of actual and potential predictability, is comparable in the two systems for both summer and winter hindcasts. Most interestingly, the multi-model prediction is often better than individual predictions in several sub-basins, including the Barents sea in the winter and most shelf seas in the summer. Systematic biases are also reduced using the multi-model predictions. Results from this study show that a regional zoom of global seasonal forecasts could be useful for operational needs. This study also show that the multi-model approach may be the step forward in producing accurate and reliable seasonal forecasts based on coupled global climate models.
Parkinson, Alan J; Butler, Jay C
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.
Glantz, Paul; Bourassa, Adam; Herber, Andreas; Iversen, Trond; Karlsson, Johannes; Kirkevåg, Alf; Maturilli, Marion; Seland, Øyvind; Stebel, Kerstin; Struthers, Hamish; Tesche, Matthias; Thomason, Larry
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.
Isaksen, Ivar S.A.; Gauss, Michael; Myhre, Gunnar; Walter Anthony, Katey M.; Ruppel, Carolyn
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.
Livingston, G.P.; Morrissey, L.A.
In situ observations of methane emissions from the Alaska North Slope in 1987 and 1989 provide insight into the environmental interactions regulating methane emissions and into the local- and regional-scale response of the arctic tundra to interannual environmental variability. Inferences regarding climate change are based on in situ measurements of methane emissions, regional landscape characterizations derived from Landsat Multispectral Scanner satellite data, and projected regional scale emissions based on observed interannual temperature differences and simulated changes in the spatial distribution of methane emissions. Results suggest that biogenic methane emissions from arctic tundra will be significantly perturbed by climatic change, leading to warmer summer soil temperatures and to vertical displacement of the regional water table. The effect of increased soil temperatures on methane emissions resulting from anaerobic decomposition in northern wetlands will be to both increase total emissions and to increase interannual and seasonal variability. The magnitude of these effects will be determined by those factors affecting the areal distribution of methane emission rates through regulation of the regional water table. At local scales, the observed 4.7 C increase in mid-summer soil temperatures between 1987 and 1989 resulted in a 3.2-fold increase in the rate of methane emissions from anaerobic soils.
La Farge, C.
The rapid retreat of glaciers and ice caps throughout the Canadian Arctic is exposing pristine vegetation preserved beneath cold-based ice. For the past half century this vegetation has been consistently reported as dead. This interpretation has been overturned by the successful re-growth of Little Ice Age (1550-1850 AD) bryophytes emerging from the Teardrop Glacier, Sverdrup Pass, Ellesmere Island (79° N) collected in 2009. Some populations showed regeneration in the field and lab experiments confirmed their capacity to regrow. The species richness of these subglacial populations is exceptional, comprising >62 species that represent 44% of the extant bryophyte flora of Sverdrup Pass. Cold-based glaciers are known to provide critical habitats for a variety of microbiota (i.e., fungi, algae, cyanobacteria, bacteria and viruses) in high latitude ecosystems. The regeneration of Little Ice Age bryophytes fundamentally expands the concept of biological refugia to land plants that was previously restricted to survival above and beyond glacial margins. Given this novel understanding of subglacial ecosystems, fieldwork is now being extended southward to plateau ice caps on Baffin Island, Nunavut, where ice retreat is exposing subglacial populations of greater antiquity (thousands to tens of thousands of radiocarbon years before present). Bryophytes by nature are totipotent (stem cell equivalency) and poikilohydric (desiccation tolerance), which facilitate their unique adaptation to extreme environments. Continuity of the Arctic bryophyte flora extends back through the Holocene to the late Tertiary [Beaufort Fm, 2-5 Ma], when the majority of taxa were the same, based on records spanning the archipelago from Ellesmere to Banks Island. This record contrasts with that of vascular plants, which have had a number of extinctions, necessitating recolonization of arctic populations from outside the region. The biological significance of a stable bryophyte element highlights their
Allan, J; Ronholm, J; Mykytczuk, N C S; Greer, C W; Onstott, T C; Whyte, L G
Increasing permafrost thaw, driven by climate change, has the potential to result in organic carbon stores being mineralized into carbon dioxide (CO2) and methane (CH4) through microbial activity. This study examines the effect of increasing temperature on community structure and metabolic activity of methanogens from the Canadian High Arctic, in an attempt to predict how warming will affect microbially controlled CH4 soil flux. In situ CO2 and CH4 flux, measured in 2010 and 2011 from ice-wedge polygons, indicate that these soil formations are a net source of CO2 emissions, but a CH4 sink. Permafrost and active layer soil samples were collected at the same sites and incubated under anaerobic conditions at warmer temperatures, with and without substrate amendment. Gas flux was measured regularly and indicated an increase in CH4 flux after extended incubation. Pyrosequencing was used to examine the effects of an extended thaw cycle on methanogen diversity and the results indicate that in situ methanogen diversity, based on the relative abundance of the 16S ribosomal ribonucleic acid (rRNA) gene associated with known methanogens, is higher in the permafrost than in the active layer. Methanogen diversity was also shown to increase in both the active layer and permafrost soil after an extended thaw. This study provides evidence that although High Arctic ice-wedge polygons are currently a sink for CH4, higher arctic temperatures and anaerobic conditions, a possible result of climate change, could result in this soil becoming a source for CH4 gas flux.
Normandeau, A.; Lamoureux, S. F.; Lajeunesse, P.; Francus, P.
High Arctic lakes are commonly used for paleoclimatic reconstructions because they are particularly sensitive to climate variability. However, the processes leading to sediment deposition and distribution in these lakes are often poorly understood. Here for the first time in the Canadian High Arctic, we present original data resulting from swath bathymetry and subbottom surveys carried out on two lakes at Cape Bounty, Melville Island. The results reveal the dynamic nature of the lakes, in which mass movement deposits and bedforms on the deltas reflect frequent slope instabilities and hyperpycnal flow activity. The analysis of the mass movement deposits reveals that small blocky debris flows/avalanches, debris flows, and a slide occurred during the Holocene. These mass movements are believed to have been triggered by earthquakes and potentially by permafrost thawing along the shoreline. Altogether, these mass movement deposits cover more than 30% of the lake floors. Additionally, the river deltas on both lakes were mapped and reveal the presence of several gullies and bedforms. The presence of gullies along the delta front indicates that hyperpycnal flows generated at the river mouth can transport sediment in different trajectories downslope, resulting in a different sediment accumulation pattern and record. The dynamic nature of these two lakes suggests that further analysis on sediment transport and distribution within Arctic lakes is required in order to improve paleoclimatic reconstructions.
De Boer, G.; Shupe, M.D.; Caldwell, P.M.; Bauer, Susanne E.; Persson, O.; Boyle, J.S.; Kelley, M.; Klein, S.A.; Tjernstrom, M.
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.
Allen, Geraldine A; Marr, Kendrick L; McCormick, Laurie J; Hebda, Richard J
The ranges of arctic-alpine species have shifted extensively with Pleistocene climate changes and glaciations. Using sequence data from the trnH-psbA and trnT-trnL chloroplast DNA spacer regions, we investigated the phylogeography of the widespread, ancient (>3 million years) arctic-alpine plant Oxyria digyna (Polygonaceae). We identified 45 haplotypes and six highly divergent major lineages; estimated ages of these lineages (time to most recent common ancestor, T(MRCA)) ranged from ∼0.5 to 2.5 million years. One lineage is widespread in the arctic, a second is restricted to the southern Rocky Mountains of the western United States, and a third was found only in the Himalayan and Altai regions of Asia. Three other lineages are widespread in western North America, where they overlap extensively. The high genetic diversity and the presence of divergent major cpDNA lineages within Oxyria digyna reflect its age and suggest that it was widespread during much of its history. The distributions of individual lineages indicate repeated spread of Oxyria digyna through North America over multiple glacial cycles. During the Last Glacial Maximum it persisted in multiple refugia in western North America, including Beringia, south of the continental ice, and within the northern limits of the Cordilleran ice sheet. Our data contribute to a growing body of evidence that arctic-alpine species have migrated from different source regions over multiple glacial cycles and that cryptic refugia contributed to persistence through the Last Glacial Maximum.
Lehnherr, I.; St. Louis, V. L.
Some species of freshwater fish in the Canadian high Arctic contain levels of methylmercury (MeHg) that pose health risks to the northern Inuit peoples that harvest these species as a traditional food source. In temperate regions, wetlands are known natural sites of MeHg production and hence significant MeHg sources to downstream ecosystems. However, the importance of wetlands to Hg methylation in the Arctic is unclear and the sources of MeHg to arctic freshwater ecosystems are still largely unidentified. Our research is demonstrating that some shallow and warm wetland ponds on the Arctic landscape contain high MeHg concentrations compared to nearby deep and cold lakes. We used a mass-balance approach to measure the net in-pond production of MeHg in two warm wetland ponds (Ponds 1 and 2) near Lake Hazen, Ellesmere Island, Nunavut (81° N latitude). We quantified external inputs and outputs of MeHg to and from the ponds, as well as the accumulation of MeHg in the water column during the summers of 2005 and 2008. Any changes in water column MeHg concentrations that could not be accounted for by external inputs or sinks were attributed to in-pond production. The principal external input and sink of MeHg was, respectively, wet atmospheric deposition and water-column MeHg photodemethylation. For 2005, we estimate that the net flux of MeHg from sediments into the water column was 0.015 μg m-2 d-1 in Pond 1 and 0.0016 μg m-2 d-1 in Pond 2. Compared to sediment-water MeHg fluxes measured in Alaskan tundra lakes (0.0015-0.0045 μg m-2 d-1), Pond 1 sediments are a greater source of MeHg while Pond 2 is similar to the Alaskan lakes. Furthermore, the accumulation of MeHg in the water column of Pond 1 (0.0061 μg m-2 d-1) was similar to the net yield of MeHg from temperate boreal wetlands (0.0005-0.006 μg m-2 d-1), demonstrating that these Arctic wetlands are important sites of MeHg production. In addition, we used mercury stable-isotope tracers to quantify methylation and
Sheng, Y.; Smith, L. C.; Li, J.; Lyons, E. A.; Wang, J.
The Arctic and Sub-Arctic regions are the home to the world's largest quantity of terrestrial lakes. These lakes play a preeminent role in the global water cycle and balance, are sensitive to global warming, and are vital for human and animal water supply. However, they are poorly observed, and a uniform lake inventory is unavailable at the pan-Arctic scale. Though there have been studies of Arctic lake dynamics at local scales, the general picture of Arctic lake change stays unclear. A systematic regional-scale assessment of Arctic lake change in the past ~30 years is crucial for us to address "How have Arctic lakes responded to global warming?" The presentation reports a systematic effort of high-latitude (45N and north) lake inventory using recently available high-resolution satellite imagery. Since Arctic lakes are abundant in small-size classes and their seasonality varies from region to region, pan-Arctic lake mapping requires the use of thousands of cloud-free Landsat images acquired in lake-stable seasons. Nearly eight million lakes have been mapped in various landscapes of the pan-Arctic using automated lake identification algorithms with high replicability. Lake-abundant regions are selected using a systematic sampling strategy to detect decadal lake change using the mid-1970s and circa-2000 Landsat imagery. Spatial patterns of the observed lake dynamics are analyzed at regional scales and the relationship between lake abundance and size distribution is investigated.
Blaschek, Michael; Renssen, Hans
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-
Hansen, K. M.; Christensen, J. H.; Geels, C.; Silver, J. D.; Brandt, J.
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
Cancet, Mathilde; Andersen, Ole; Lyard, Florent; Cotton, David; Benveniste, Jérôme
The Arctic Ocean is a challenging region for tidal modeling, because of its complex and not well-documented bathymetry, together combined with the intermittent presence of sea ice and the fact that the in situ tidal observations are scarce at such high latitudes. As a consequence, the accuracy of the global tidal models decreases by several centimeters in the Polar Regions. It has a large impact on the quality of the satellite altimeter sea surface heights in these regions (ERS1/2, Envisat, CryoSat-2, SARAL/AltiKa and the future Sentinel-3 mission), but also on the end-users' applications that need accurate tidal information. Better knowledge of the tides will improve the quality of the high latitudes altimeter sea surface heights and of all derived products, such as the altimetry-derived geostrophic currents, the mean sea surface and the mean dynamic topography. In addition, accurate tidal models are highly strategic information for ever-growing maritime and industrial activities in this region. NOVELTIS and DTU Space have recently developed a regional, high-resolution tidal atlas in the Arctic Ocean, in the framework of an extension of the CryoSat Plus for Oceans (CP4O) project funded by ESA (STSE program). In particular, this atlas benefits from the assimilation of the most complete satellite altimetry dataset ever used in this region, including the Envisat data up to 82°N and the CryoSat-2 reprocessed data between 82°N and 88°N. The combination of all these satellites gives the best possible coverage of altimetry-derived tidal constituents. Tide gauge data have also been used either for assimilation or validation. This paper presents the methodology followed to develop the model and the performances of this new regional tidal model in the Arctic Ocean.
Lucia, Magali; Verboven, Nanette; Strøm, Hallvard; Miljeteig, Cecilie; Gavrilo, Maria V; Braune, Birgit M; Boertmann, David; Gabrielsen, Geir W
The ivory gull Pagophila eburnea is a high-Arctic species threatened by climate change and contaminants. The objective of the present study was to assess spatial variation of contaminant levels (organochlorines [OCs], brominated flame retardants [BFRs], perfluorinated alkyl substances [PFASs], and mercury [Hg]) in ivory gulls breeding in different areas across the Arctic region as a baseline for potential future changes associated with climate change. Contaminants were already determined in eggs from Canada (Seymour Island; except PFASs), Svalbard in Norway (Svenskøya), and 3 sites in Russia (Nagurskoe, Cape Klyuv, and Domashny). New data from Greenland allowed the investigation of a possible longitudinal gradient of contamination. The most quantitatively abundant OCs were p,p'-dichlorodiphenyldichloroethylene (DDE) and polychlorobiphenyls. Mercury concentrations were higher in Canada compared with other colonies. Eggs from Nagurskoe often were characterized by higher OC and BFR concentrations. Concentrations gradually decreased in colonies situated east of Nagurskoe. In contrast, PFAS concentrations, especially perfluorooctanoate and perfluorononanoate, were higher in Greenland. Some of the contaminants, especially Hg and p,p'-DDE, exceeded published thresholds known to disrupt the reproductive success of avian species. Overall, the levels of OCs, BFRs, and PFASs did not suggest direct lethal exposure to these compounds, but their potential synergetic/additive sublethal effects warrant monitoring.
Griffiths, Katherine; Michelutti, Neal; Sugar, Madeline; Douglas, Marianne S V; Smol, John P
Recent climate change has been especially pronounced in the High Arctic, however, the responses of aquatic biota, such as diatoms, can be modified by site-specific environmental characteristics. To assess if climate-mediated ice cover changes affect the diatom response to climate, we used paleolimnological techniques to examine shifts in diatom assemblages from ten High Arctic lakes and ponds from Ellesmere Island and nearby Pim Island (Nunavut, Canada). The sites were divided a priori into four groups ("warm", "cool", "cold", and "oasis") based on local elevation and microclimatic differences that result in differing lengths of the ice-free season, as well as about three decades of personal observations. We characterized the species changes as a shift from Condition 1 (i.e. a generally low diversity, predominantly epipelic and epilithic diatom assemblage) to Condition 2 (i.e. a typically more diverse and ecologically complex assemblage with an increasing proportion of epiphytic species). This shift from Condition 1 to Condition 2 was a consistent pattern recorded across the sites that experienced a change in ice cover with warming. The "warm" sites are amongst the first to lose their ice covers in summer and recorded the earliest and highest magnitude changes. The "cool" sites also exhibited a shift from Condition 1 to Condition 2, but, as predicted, the timing of the response lagged the "warm" sites. Meanwhile some of the "cold" sites, which until recently still retained an ice raft in summer, only exhibited this shift in the upper-most sediments. The warmer "oasis" ponds likely supported aquatic vegetation throughout their records. Consequently, the diatoms of the "oasis" sites were characterized as high-diversity, Condition 2 assemblages throughout the record. Our results support the hypothesis that the length of the ice-free season is the principal driver of diatom assemblage responses to climate in the High Arctic, largely driven by the establishment of new
Griffiths, Katherine; Michelutti, Neal; Sugar, Madeline; Douglas, Marianne S. V.; Smol, John P.
Recent climate change has been especially pronounced in the High Arctic, however, the responses of aquatic biota, such as diatoms, can be modified by site-specific environmental characteristics. To assess if climate-mediated ice cover changes affect the diatom response to climate, we used paleolimnological techniques to examine shifts in diatom assemblages from ten High Arctic lakes and ponds from Ellesmere Island and nearby Pim Island (Nunavut, Canada). The sites were divided a priori into four groups (“warm”, “cool”, “cold”, and “oasis”) based on local elevation and microclimatic differences that result in differing lengths of the ice-free season, as well as about three decades of personal observations. We characterized the species changes as a shift from Condition 1 (i.e. a generally low diversity, predominantly epipelic and epilithic diatom assemblage) to Condition 2 (i.e. a typically more diverse and ecologically complex assemblage with an increasing proportion of epiphytic species). This shift from Condition 1 to Condition 2 was a consistent pattern recorded across the sites that experienced a change in ice cover with warming. The “warm” sites are amongst the first to lose their ice covers in summer and recorded the earliest and highest magnitude changes. The “cool” sites also exhibited a shift from Condition 1 to Condition 2, but, as predicted, the timing of the response lagged the “warm” sites. Meanwhile some of the “cold” sites, which until recently still retained an ice raft in summer, only exhibited this shift in the upper-most sediments. The warmer “oasis” ponds likely supported aquatic vegetation throughout their records. Consequently, the diatoms of the “oasis” sites were characterized as high-diversity, Condition 2 assemblages throughout the record. Our results support the hypothesis that the length of the ice-free season is the principal driver of diatom assemblage responses to climate in the High Arctic
Galloway, Jennifer; Ernst, Richard; Hadlari, Thomas
The Sverdrup Basin is an east-west-trending extensional sedimentary basin underlying the northern Canadian Arctic Archipelago. The tectonic history of the basin began with Carboniferous-Early Permian rifting followed by thermal subsidence with minor tectonism. Tectonic activity rejuvenated in the Hauterivian-Aptian by renewed rifting and extension. Strata were deformed by diapiric structures that developed during episodic flow of Carboniferous evaporites during the Mesozoic and the basin contains igneous components associated with the High Arctic Large Igneous Province (HALIP). HALIP was a widespread event emplaced in multiple pulses spanning ca. 180 to 80 Ma, with igneous rocks on Svalbard, Franz Josef Island, New Siberian Islands, and also in the Sverdrup Basin on Ellef Ringnes, Axel Heiberg, and Ellesmere islands. Broadly contemporaneous igneous activity across this broad Arctic region along with a reconstructed giant radiating dyke swarm suggests that HALIP is a manifestation of large mantle plume activity probably centred near the Alpha Ridge. Significant surface uplift associated with the rise of a mantle plume is predicted to start ~10-20 my prior to the generation of flood basalt magmatism and to vary in shape and size subsequently throughout the LIP event (1,2,3) Initial uplift is due to dynamical support associated with the top of the ascending plume reaching a depth of about 1000 km, and with continued ascent the uplift topography broadens. Additional effects (erosion of the ductile lithosphere and thermal expansion caused by longer-term heating of the mechanical lithosphere) also affect the shape of the uplift. Topographic uplift can be between 1 to 4 km depending on various factors and may be followed by subsidence as the plume head decays or become permanent due to magmatic underplating. In the High Arctic, field and geochronological data from HALIP relevant to the timing of uplift, deformation, and volcanism are few. Here we present new evidence
Rogers, M.; Welker, J.; Sullivan, P.; Sletten, R.; Arens, S.; Kristenson, H.
Winter climate conditions are changing throughout the Arctic. In Greenland, there are observed increases in snowfall across portions of the island while the margins of the Greenland Ice Sheet are thinning. However, these changes and the consequences of altered meteorological surface dynamics on High Arctic terrestrial ecosystems and their potential feedbacks are unclear. Increases in winter snow cover may cause warmer soils in winter, greater rates of winter C losses, increases in winter N mineralization, shorter growing seasons and reduced net C gain in summer due to either reduced gross photosynthesis or increases in ecosystem respiration. In our study, we have constructed replicated snow fences in prostrate dwarf shrub tundra (polar desert and semi- desert) ecosystems in NW Greenland. Our measurements were taken at the deep (1.0 m snow depth) and intermediate (0.35 m snow depth) points along the drift to address these questions: a) how do increases in snow depth alter the surface and subsurface physical and chemical processes of these ecosystems?, and b) to what extent do increases in snow depth alter net CO2 exchange, gross ecosystem photosynthesis and ecosystem respiration? After three years of treatment we have found that in winter, deep snow results in warmer soil temperatures and in the subsequent summer, areas with deep winter snow have colder soil temperatures. This effect is most pronounced immediately following snowmelt and temperatures slowly return to ambient conditions near the end of summer. Deeper snow results in higher soil water contents in early summer, but by mid-July soil water contents have returned to ambient levels. Net ecosystem CO2 exchange rates are consistently negative (CO2 source to the atmosphere) through most of the growing season and vary in their magnitude by snow depth and ecosystem type. Areas with the deepest snow during winter consistently have the largest rates of CO2 loss to the atmosphere. The middle snow depth treatment
Kaarlejärvi, Elina; Hoset, Katrine S; Olofsson, Johan
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.
Herrle, Jens; Schröder-Adams, Claudia; Selby, David; Du Vivier, Alice; Flögel, Sascha; McAnena, Alison; Davis, William; Pugh, Adam; Galloway, Jennifer; Hofmann, Peter; Wagner, Thomas
Although major progress in Cretaceous (145-66 Ma) paleoclimate and paleoceanography has been made during the last decades (e.g., Hay, 2008, 2011; Föllmi, 2012 and references therein), our knowledge of high latitudinal environmental change remains largely unknown compared to low- and mid-latitude marine and terrestrial environments. Drilling the Arctic Ocean remains challenging and expensive, whereas the Sverdrup Basin provides excellent exposures on land. To fully understand the climate and paleoceanographic dynamics of the warm, equable greenhouse world of the Cretaceous Period it is important to determine polar paleotemperatures and to study paleoceanographic changes in a well-established and continuous bio- and chemostratigraphic context. Exceptional exposures of Cretaceous sediments on the central to southern part of Axel Heiberg Island at a Cretaceous paleolatitude of about 71°N (Tarduno et al., 1998) provide a unique window on the Cretaceous Arctic paleoenvironment and climate history (Schröder-Adams et al., 2014). Here we present high-resolution records combining sedimentological studies, U-Pb zircon geochronology, marine organic carbon isotopes and initial 187Os/188Os data, TEX86-derived sea-surface temperatures (SST) and climate modelling, that constrain the timing and magnitude of major Oceanic Anoxic Events (OAEs) and climate events constructed from a ~1.8 km sedimentary succession exposed on Axel Heiberg and Ellef Ringnens islands in the Canadian Arctic Archipelago. The first high latitude application of initial 187Os/188Os data are agreeable with global profiles (Du Vivier et al., 2014) indicating the widespread magmatic pulse of the Caribbean Large Igneous Province (LIP) at the onset of OAE2 but also record the emplacement of local High Arctic LIP prior to the OAE2 in the Sverdrup Basin. Initial SST data suggest a slightly lower meridional temperature gradient during the Middle/Late Albian compared to present and a similar to the present one during
Portnov, Alexey; Mienert, Jurgen; Serov, Pavel
Thawing subsea permafrost controls methane release from the Russian Arctic shelf having a considerable impact on the climate-sensitive Arctic environment. Expulsions of methane from shallow Russian Arctic shelf areas may continue to rise in response to intense degradation of relict subsea permafrost. Here we show modeling of the permafrost evolution from the Late Pleistocene to present time at the West Yamal shelf. Modeling results suggest a highly dynamic permafrost system that directly responds to even minor variations of lower and upper boundary conditions, e.g., geothermal heat flux from below and/or bottom water temperature changes from above permafrost. Scenarios of permafrost evolution show a potentially nearest landward modern extent of the permafrost at the West Yamal shelf limited by ~17 m isobaths, whereas its farthest seaward extent coincides with ~100 m isobaths. The model also predicts seaward tapering of relict permafrost with a maximal thickness of 275-390 m near the shoreline. Previous field observations detected extensive emissions of free gas into the water column at the transition zone between today's shallow water permafrost (<20 m) and deeper water nonpermafrost areas (>20 m). The model adapts well to corresponding heat flux and ocean temperature data, providing crucial information about the modern permafrost conditions. It shows current locations of upper and lower permafrost boundaries and evidences for possible release of methane from the seabed to the hydrosphere in a warming Arctic.
Hansen, K. M.; Christensen, J. H.; Geels, C.; Silver, J. D.; Brandt, J.
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
environment. 15. SUBJECT TERMS US Army Cold Weather Doctrine; US Army Arctic Operational Capability; ULO; Mission Command; Arctic Council; UNCLOS...http://www.arctic.gov/maps.html. Within this defined geographical area of the Arctic, there are diverse terrains and weather conditions that impact...continuous Arctic operations.23 Although warming presents numerous mobility challenges, the region’s extreme cold weather exponentially increases the
Meier, W. N.; Youngman, E.; Dahlman, L.
Arctic sea ice is declining rapidly. Since 2002, summer Arctic sea ice extents have been at record or near-record lows; winter extents have also showed a marked decline. Even in comparison to the previous five extreme low years, the 2007 summer melt season has been stunning, with dramatically less ice than the previous record in 2005. This is further evidence that the Arctic sea ice may have already passed a tipping point toward a state without ice during the summer by 2050 or before. Such a change will have profound impacts on climate as well as human and wildlife activities in the region. The "Whither Arctic Sea Ice?" Earth Exploration Toolbook chapter (http://serc.carleton.edu/eet/seaice/index.html) exposes students to satellite-derived sea ice data and allows them to process and interpret the data to "discover" these sea ice changes for themselves. A sample case study in Hudson Bay has been developed that relates the physical changes occurring on the sea ice to peoples and wildlife that depend on the ice for their livelihood. This approach provides a personal connection for students and allows them to relate to the impacts of the changes. Suggestions are made for further case studies that can be developed using the same data relating to topical events in the Arctic. The EET chapter exposes students to climate change, scientific data, statistical concepts, and image processing software providing an avenue for the communication of IPY data and science to teachers and students.
Finkenbinder, M. S.; Abbott, M. B.; Dorfman, J. M.; Finney, B.; Stoner, J. S.
Millennial-scale fluctuations in climate conditions are commonly observed in Holocene paleoclimate archives, however the meaning of these variations including whether they might arise from internal or external forcing are still actively debated. Proxy evidence of millennial-scale variability is most clearly present in a few specific parts of the world (e.g. North Atlantic region), whereas a lack of evidence from many other regions may result from a lack of observations or a lack of signal. Here we present the first evidence for such variations in Arctic Alaska using sedimentological and geochemical analyses from Burial Lake (68.43°N, 159.17°W; 460 m above sea level) in the western Brooks Range. We measured biogenic silica (BSi), total organic carbon, total nitrogen, C/N ratios, dry bulk density, magnetic susceptibility and magnetic remanence measurements, and elemental abundances from scanning XRF and use radiocarbon dating on terrestrial macrofossils to establish age control. Large fluctuations in biogenic silica and related proxies at millennial time scales over the last 10,000 cal yr BP are attributed to changes in aquatic productivity, which is indirectly mediated by climate through changes in the duration of the ice-free growing season and the availability of limiting nutrients. Spectral and wavelet analysis of the BSi record indicates a significant 1,500-yr cycle (above 95% confidence) emerges by ~6,000 cal yr BP. Comparison of BSi with reconstructed total solar irradiance reveals a low correlation (r2 = 0.01), suggesting no direct solar forcing of aquatic productivity. A comparison with Northern Hemisphere wide records shows no consistent phase relationship between the timing of maxima/minima in our BSi record. These results are consistent with previous work showing a strong middle Holocene transition into a ~1500-yr cycle. Similar timing for the emergence of an ~1500-yr cycle are found in proxies sensitive to thermohaline circulation and deep water
Wu, Xiaoguo; Lam, James C W; Xia, Chonghuan; Kang, Hui; Sun, Liguang; Xie, Zhouqing; Lam, Paul K S
From July to September 2008, air samples were collected aboard the research expedition icebreaker XueLong (Snow Dragon) as part of the 2008 Chinese Arctic Research Expedition Program. Hexachlorocyclohexane (HCH) concentrations were analyzed in all of the samples. The average concentrations (± standard deviation) over the entire period were 33 ± 16, 5.4 ± 3.0, and 13 ± 7.5 pg m⁻³ for α-, β- and γ-HCH, respectively. Compared to previous studies in the same areas, total HCH (ΣHCH, the sum of α-, β-, and γ-HCH) levels declined by more than 10 × compared to those observed in the 1990s, but were approximately 4 × higher than those measured by the 2003 China Arctic Research Expedition, suggesting the increase of atmospheric ΣHCH recently. Because of the continuing use of lindane, ratios of α/γ-HCH showed an obvious decrease in North Pacific and Arctic region compared with those for 2003 Chinese Arctic Research Expedition. In Arctic, the level of α-HCH was found to be linked to sea ice distribution. Geographically, the average concentration of α-HCH in air samples from the Chukchi and Beaufort Seas, neither of which contain sea ice, was 23 ± 4.4 pg m⁻³, while samples from the area covered by seasonal ice (∼75°N to ∼83°N), the so-called "floating sea ice region", contained the highest average levels of α-HCH at 48 ± 12 pg m⁻³, likely due to emission from sea ice and strong air-sea exchange. The lowest concentrations of α-HCH were observed in the pack ice region in the high Arctic covered by multiyear sea ice (∼83°N to ∼86°N). This phenomenon implies that the re-emission of HCH trapped in ice sheets and Arctic Ocean may accelerate during the summer as ice coverage in the Arctic Ocean decreases in response to global climate change.
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.
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
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.
Street, Lorna E; Burns, Nancy R; Woodin, Sarah J
Arctic ecosystems are strongly nutrient limited and exhibit dramatic responses to nitrogen (N) enrichment, the reversibility of which is unknown. This study uniquely assesses the potential for tundra heath to recover from N deposition and the influence of phosphorus (P) availability on recovery. We revisited an experiment in Svalbard, established in 1991, in which N was applied at rates representing atmospheric N deposition in Europe (10 and 50 kg N ha(-1) yr(-1) ; 'low' and 'high', respectively) for 3-8 yr. We investigated whether significant effects on vegetation composition and ecosystem nutrient status persisted up to 18 yr post-treatment. Although the tundra heath is no longer N saturated, N treatment effects persist and are strongly P-dependent. Vegetation was more resilient to N where no P was added, although shrub cover is still reduced in low-N plots. Where P was also added (5 kg P ha(-1) yr(-1) ), there are still effects of low N on community composition and nutrient dynamics. High N, with and without P, has many lasting impacts. Importantly, N + P has caused dramatically increased moss abundance, which influences nutrient dynamics. Our key finding is that Arctic ecosystems are slow to recover from even small N inputs, particularly where P is not limiting.
Schütte, Ursel M.E.; Abdo, Zaid; Bent, Stephen J.; Williams, Christopher J.; Schneider, G. Maria; Solheim, Bjørn; Forney, Larry J.
Succession is defined as changes in biological communities over time. It has been extensively studied in plant communities, but little is known about bacterial succession, in particular in environments such as High Arctic glacier forelands. Bacteria carry out key processes in the development of soil, biogeochemical cycling, and facilitating plant colonization. In this study we sampled two roughly parallel chronosequences in the foreland of Midre Lovén glacier on Svalbard, Norway and tested whether any of several factors were associated with changes in the structure of bacterial communities, including time after glacier retreat, horizontal variation caused by the distance between chronosequences, and vertical variation at two soil depths. The structures of soil bacterial communities at different locations were compared using terminal restriction fragment length polymorphisms (T-RFLP) of 16S rRNA genes, and the data were analyzed by sequential analysis of log-linear statistical models. While no significant differences in community structure were detected between the two chronosequences, statistically significant differences between sampling locations in the surface and mineral soils could be demonstrated even though glacier forelands are patchy and dynamic environments. These findings suggest bacterial succession occurs in High Arctic glacier forelands but may differ in different soil depths. PMID:19587774
Lau, M C Y; Stackhouse, B T; Layton, A C; Chauhan, A; Vishnivetskaya, T A; Chourey, K; Ronholm, J; Mykytczuk, N C S; Bennett, P C; Lamarche-Gagnon, G; Burton, N; Pollard, W H; Omelon, C R; Medvigy, D M; Hettich, R L; Pfiffner, S M; Whyte, L G; Onstott, T C
Methane (CH4) emission by carbon-rich cryosols at the high latitudes in Northern Hemisphere has been studied extensively. In contrast, data on the CH4 emission potential of carbon-poor cryosols is limited, despite their spatial predominance. This work employs CH4 flux measurements in the field and under laboratory conditions to show that the mineral cryosols at Axel Heiberg Island in the Canadian high Arctic consistently consume atmospheric CH4. Omics analyses present the first molecular evidence of active atmospheric CH4-oxidizing bacteria (atmMOB) in permafrost-affected cryosols, with the prevalent atmMOB genotype in our acidic mineral cryosols being closely related to Upland Soil Cluster α. The atmospheric (atm) CH4 uptake at the study site increases with ground temperature between 0 °C and 18 °C. Consequently, the atm CH4 sink strength is predicted to increase by a factor of 5–30 as the Arctic warms by 5–15 °C over a century. We demonstrate that acidic mineral cryosols are a previously unrecognized potential of CH4 sink that requires further investigation to determine its potential impact on larger scales. This study also calls attention to the poleward distribution of atmMOB, as well as to the potential influence of microbial atm CH4 oxidation, in the context of regional CH4 flux models and global warming. PMID:25871932
Lau, M C Y; Stackhouse, B T; Layton, A C; Chauhan, A; Vishnivetskaya, T A; Chourey, K; Ronholm, J; Mykytczuk, N C S; Bennett, P C; Lamarche-Gagnon, G; Burton, N; Pollard, W H; Omelon, C R; Medvigy, D M; Hettich, R L; Pfiffner, S M; Whyte, L G; Onstott, T C
Methane (CH4) emission by carbon-rich cryosols at the high latitudes in Northern Hemisphere has been studied extensively. In contrast, data on the CH4 emission potential of carbon-poor cryosols is limited, despite their spatial predominance. This work employs CH4 flux measurements in the field and under laboratory conditions to show that the mineral cryosols at Axel Heiberg Island in the Canadian high Arctic consistently consume atmospheric CH4. Omics analyses present the first molecular evidence of active atmospheric CH4-oxidizing bacteria (atmMOB) in permafrost-affected cryosols, with the prevalent atmMOB genotype in our acidic mineral cryosols being closely related to Upland Soil Cluster α. The atmospheric (atm) CH4 uptake at the study site increases with ground temperature between 0 °C and 18 °C. Consequently, the atm CH4 sink strength is predicted to increase by a factor of 5-30 as the Arctic warms by 5-15 °C over a century. We demonstrate that acidic mineral cryosols are a previously unrecognized potential of CH4 sink that requires further investigation to determine its potential impact on larger scales. This study also calls attention to the poleward distribution of atmMOB, as well as to the potential influence of microbial atm CH4 oxidation, in the context of regional CH4 flux models and global warming.
Galloway, Jennifer; Grasby, Stephen; Swindles, Graeme; Dewing, Keith
Jurassic to Cretaceous strata of Sverdrup Basin, Canadian Arctic Archipelago, contain marine and non-marine successions that can be studied to reconstruct ancient paleoclimates and paleoenvironments that are poorly understood in high-latitude regions. We use element geochemistry integrated with palynology to study a continuous Aalenian to Albian-aged succession preserved in the Hoodoo Dome H-37 oil and gas well located on southern Ellef Ringnes Island near the centre of Sverdrup Basin. Cluster analysis (stratigraphically constrained incremental sum of squares; CONISS) is used to delineate four geochemical zones that are broadly coeval with major changes in palyno-assemblages interpreted to reflect changes in regional paleoclimate. Zone 1 (late Aalenian to Bathonian) is characterized by palynomorphs associated with humid and warm climate conditions. The chemical alteration index (CAI) is high in this interval, expected under this a humid and warm climate. A transition to a seasonally arid and warm climate occurred in the Bathonian and persisted until the Kimmeridgian or Valanginian (Zone 2). This interval is characterized by decreased chemical weathering, indicated by a drop in CAI. The onset of Zone 3 (Kimmeridgian or Valanginian to late Barremian or early Aptian) occurs during a transition to humid and cool climate conditions and is associated with a period of regional uplift and rifting. Zone 3 is marked by a substantial and progressive drop in CAI, indicating a transition from a weathering to transport-dominated system, possibly associated with landscape destabilization. Reduced tectonic activity in Zone 4 (early Aptian to early or mid Albian) shows a return to active chemical weathering, possibly associated with landscape stabilization, suggested by a continued increase in pollen from upland coniferous taxa. The geochemical and palynological records of Middle Jurassic to Lower Cretaceous strata of the Hoodoo Dome H-37 oil and gas well show close correlation
Rasch, P.; Wang, H.; Ma, P.; Fast, J. D.; Wang, M.; Easter, R. C.; Liu, X.; Qian, Y.; Flanner, M. G.; Ghan, S.; Singh, B.
be run at higher resolution in order to explore the resolution dependence of the parameterizations and make comparisons to field experiments more straightforward. Aerosols sources have also been tagged by sector and geographic region to help in attribution and interpretation. The many variations mentioned here help in understanding how aerosols reach the arctic and how they produce changes in radiative forcing and Arctic climate. I will provide a brief overview of these studies, with more detail available in presentations submitted to this session and elsewhere.
Chylek, Petr; Lesins, Glen K; Wang, Muyin
Increasing Arctic temperature, disappearance of Arctic sea ice, melting