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1

Extension of the PMV model to non-air-conditioned buildings in warm climates  

Microsoft Academic Search

The PMV model agrees well with high-quality field studies in buildings with HVAC systems, situated in cold, temperate and warm climates, studied during both summer and winter. In non-air-conditioned buildings in warm climates, occupants may sense the warmth as being less severe than the PMV predicts. The main reason is low expectations, but a metabolic rate that is estimated too

P. Ole Fanger; Jørn Toftum

2002-01-01

2

Computations on frost damage to Scots pine under climatic warming in boreal conditions  

SciTech Connect

To investigate the risk of frost damage to Scots pine (Pinus sylvestris L.) in northern regions under climatic warming, a submodel for such damage to trees was included in a forest ecosystem model of the gap type. An annual growth multiplier describing the effects of frost was calculated with the help of simulated daily frost hardiness and daily minimum temperature. The annual growth multiplier was used in the main ecosystem model when simulating the development of a tree stand using a time step of one year. Simulations of the growth and development of Scots pine stands in southern Finland (61{degrees} N) under an elevating temperature indicated that climatic warming could increase the risk of frost damage due to premature onset of growth during warm spells in the late winter and early spring. Risk of frost damage implies uncertainty in yield expectations from boreal forest ecosystems in the event of climatic warming. 38 refs., 9 figs., 4 tabs.

Kellomaeki, S.; Haenninen, H.; Kolstroem, M. [Univ. of Joensuu (Finland)

1995-02-01

3

Even warm climates get the shivers  

SciTech Connect

Researchers in the Greenland Ice-Core Project (GRIP) have found evidence of sharp climate shifts during the last two intergalcials. The Greenland ice sheet evidence shows that Greenland, over and over for decades to thousands of years, cooled drastically from temperatures equal to or higher than today's, often to virtual ice age conditions. The researchers believe that disruptions in the flow of warm water from the southern Atlantic to the North Atlantic, and the return flow of cold water to the south, may be linked to these climatic fluctuations. The present climate appears relatively stable, but that may change if temperatures warm due to increases in atmospheric greenhouse gases.

Kerr, R.A.

1993-07-16

4

Effects of storage conditions on hatchability of chicken eggs in a warm climate  

Microsoft Academic Search

1. A total of 3792 eggs from AF Bosbek layer parents were used to determine the effect of storage time on the hatchability of eggs kept either small end up (SEU) or small end down (SED).2. These eggs were stored at room temperature (27°C?31°C) or in an air?conditioned room (20°C?23°C), for two, three, six or seven days and incubated in

A. Antwi

1993-01-01

5

The Dynamics of Warm and Cold Climates  

Microsoft Academic Search

The atmospheric dynamics of five different climate simulations with the GISS GCM are compared to investigate the changes that occur as climate warms or cools. There are two ice age simulations, the current and doubled CO2 climates, and a simulation of the warm Cretaceous. These climates have a range of global average surface air temperature of 13°C. The results are

D. Rind

1986-01-01

6

Response of ocean ecosystems to climate warming  

Microsoft Academic Search

We examine six different coupled climate model simulations to determine the ocean biological response to climate warming between the beginning of the industrial revolution and 2050. We use vertical velocity, maximum winter mixed layer depth, and sea ice cover to define six biomes. Climate warming leads to a contraction of the highly productive marginal sea ice biome by 42% in

J. L. Sarmiento; R. Slater; R. Barber; L. Bopp; S. C. Doney; A. C. Hirst; J. Kleypas; R. Matear; U. Mikolajewicz; P. Monfray; V. Soldatov; S. A. Spall; R. Stouffer

2004-01-01

7

Response of ocean ecosystems to climate warming  

Microsoft Academic Search

We examine six different coupled climate model simulations to determine the ocean biological response to climate warming between the beginning of the industrial revolution and 2050. We use vertical velocity, maximum winter mixed layer depth, and sea ice cover to define six biomes. Climate warming leads to a contraction of the highly productive marginal sea ice biome by 42 in

J. L. Sarmiento; R. Slater; R. Barber; L. Bopp; S. C. Doney; A. C. Hirst; J. Kleypas; R. Matear; U. Mikolajewicz; P. Monfray; V. Soldatov; S. A. Spall; R. Stouffer

2004-01-01

8

Warming asymmetry in climate change simulations  

Microsoft Academic Search

Climate change simulations made with coupled global climate models typically show a marked hemispheric asymmetry with more warming in the northern high lati- tudes than in the south. This asymmetry is ascribed to heat uptake by the ocean at high southern latitudes. A re- cent version of the CCCma climate model exhibits a much more symmetric warming, compared to an

G. M. Flato; G. J. Boer

2001-01-01

9

Soil degradation, global warming and climate impacts  

E-print Network

will demonstrate one methodology for assessing the potential large-scale impacts of soil degradation on African climates and water resources. In addition it will compare and contrast these impacts to those expected from global warming and compare impacts for differ...- ent watershed regions on the continent. 2. METHODS In order to make a similar comparison between pro- jected climate change scenarios due to global warming © Inter-Research 2001 *E-mail: feddema@ku.edu Soil degradation, global warming and climate...

Feddema, Johannes J.; Freire, Sergio Carneiro

2001-01-01

10

Effects of climate warming, North Atlantic Oscillation, and El Niño-Southern Oscillation on thermal conditions and plankton dynamics in northern hemispheric lakes.  

PubMed

Impacts of climate warming on freshwater ecosystems have been documented recently for a variety of sites around the globe. Here we provide a review of studies that report long-term (multidecadal) effects of warming trends on thermal properties and plankton dynamics in northern hemispheric lakes. We show that higher lake temperatures, shorter periods with ice cover, and shorter stagnation periods were common trends for lakes across the hemisphere in response to the warmer conditions. Only for shallow dimictic lakes was it observed that deep-water temperatures decreased. Moreover, it became evident that phytoplankton dynamics and primary productivity altered in conjunction with changes in lake physics. Algal spring blooms developed early and were more pronounced in several European lakes after mild winters with short ice cover periods, and primary productivity increased in North American lakes. Effects of elevated temperatures on zooplankton communities were seen in an early development of various species and groups, as is documented for cladocerans, copepods, and rotifers in European lakes. Furthermore, thermophile species reached higher abundance in warmer years. Obviously, the nature of responses is species specific, and depends on the detailed seasonal patterning of warming. Complex responses such as effects propagating across trophic levels are likely, indicating that observed climate-ecosystem relationships are not generally applicable. Nonetheless, the picture emerges that climate-driven changes in freshwater ecosystems may be synchronised to a certain extent among lakes even over great distances if climatic influences are not masked by anthropogenic impacts or differences in lake morphology. Macro-scale climatic fluctuations--such as the North Atlantic Oscillation or the El Niño-Southern Oscillation--were identified as the most important candidates responsible for such coherence, with the former predominating in Europe and the latter in North America. We emphasise, however, that the driving mechanisms and the future behaviour of these oscillations are rather uncertain, which complicates extrapolation of observed effects into the future. Thus, it is necessary to quantify the most important climate-ecosystem relationships in models of appropriate complexity. Such models will help elucidate the multiple pathways climate affects freshwater ecosystems, and will indicate possible adverse effects of a warmer future climate. PMID:12805986

Gerten, Dieter; Adrian, Rita

2002-03-01

11

State-dependent climate sensitivity in past warm climates and its implications for future climate projections  

PubMed Central

Projections of future climate depend critically on refined estimates of climate sensitivity. Recent progress in temperature proxies dramatically increases the magnitude of warming reconstructed from early Paleogene greenhouse climates and demands a close examination of the forcing and feedback mechanisms that maintained this warmth and the broad dynamic range that these paleoclimate records attest to. Here, we show that several complementary resolutions to these questions are possible in the context of model simulations using modern and early Paleogene configurations. We find that (i) changes in boundary conditions representative of slow “Earth system” feedbacks play an important role in maintaining elevated early Paleogene temperatures, (ii) radiative forcing by carbon dioxide deviates significantly from pure logarithmic behavior at concentrations relevant for simulation of the early Paleogene, and (iii) fast or “Charney” climate sensitivity in this model increases sharply as the climate warms. Thus, increased forcing and increased slow and fast sensitivity can all play a substantial role in maintaining early Paleogene warmth. This poses an equifinality problem: The same climate can be maintained by a different mix of these ingredients; however, at present, the mix cannot be constrained directly from climate proxy data. The implications of strongly state-dependent fast sensitivity reach far beyond the early Paleogene. The study of past warm climates may not narrow uncertainty in future climate projections in coming centuries because fast climate sensitivity may itself be state-dependent, but proxies and models are both consistent with significant increases in fast sensitivity with increasing temperature. PMID:23918397

Caballero, Rodrigo; Huber, Matthew

2013-01-01

12

Indian Ocean warming modulates Pacific climate change  

PubMed Central

It has been widely believed that the tropical Pacific trade winds weakened in the last century and would further decrease under a warmer climate in the 21st century. Recent high-quality observations, however, suggest that the tropical Pacific winds have actually strengthened in the past two decades. Precise causes of the recent Pacific climate shift are uncertain. Here we explore how the enhanced tropical Indian Ocean warming in recent decades favors stronger trade winds in the western Pacific via the atmosphere and hence is likely to have contributed to the La Niña-like state (with enhanced east–west Walker circulation) through the Pacific ocean–atmosphere interactions. Further analysis, based on 163 climate model simulations with centennial historical and projected external radiative forcing, suggests that the Indian Ocean warming relative to the Pacific’s could play an important role in modulating the Pacific climate changes in the 20th and 21st centuries. PMID:23112174

Luo, Jing-Jia; Sasaki, Wataru; Masumoto, Yukio

2012-01-01

13

Can warming particles enter global climate discussions?  

NASA Astrophysics Data System (ADS)

'Soot' or 'black carbon', which comes from incomplete combustion, absorbs light and warms the atmosphere. Although there have been repeated suggestions that reduction of black carbon could be a viable part of decreasing global warming, it has not yet been considered when choosing actions to reduce climatic impact. In this paper, I examine four conceptual barriers to the consideration of aerosols in global agreements. I conclude that some of the major objections to considering aerosols under hemispheric or global agreements are illusory because: (1) a few major sources will be addressed by local regulations, but the remainder may not be addressed by traditional air quality management; (2) climate forcing by carbon particles is not limited to 'hot spots'—about 90% of it occurs at relatively low concentrations; (3) while aerosol science is complex, the most salient characteristics of aerosol behavior can be condensed into tractable metrics including, but not limited to, the global warming potential; (4) despite scientific uncertainties, reducing all aerosols from major sources of black carbon will reduce direct climate warming with a very high probability. This change in climate forcing accounts for at least 25% of the accompanying CO2 forcing with significant probability (25% for modern diesel engines, 90% for superemitting diesels, and 55% for cooking with biofuels). Thus, this fraction of radiative forcing should not be ignored.

Bond, Tami C.

2007-10-01

14

WHAT'S IN A NAME? GLOBAL WARMING VERSUS CLIMATE CHANGE  

E-print Network

WHAT'S IN A NAME? GLOBAL WARMING VERSUS CLIMATE CHANGE May 2014 #12;What's In A Name? Global NATIONAL SURVEY STUDY 2: GLOBAL WARMING VS. CLIMATE CHANGE............................ 10 Is global?................................................................10 When you think of global warming / climate change, what comes first to mind

Haller, Gary L.

15

Study of landscape change under forest harvesting and climate warming-induced fire disturbance  

E-print Network

(lakeshore) ecoregion under warming conditions, boreal and northern hardwood species such as red oak, sugar climate warming. Southern species such as white ash, hickory, bur oak, black oak, and white oak, which 0 5 6 3 - 1 #12;direct impacts of warming on tree physiology at small scales can accumulate

He, Hong S.

16

Climate warming will not decrease winter mortality  

NASA Astrophysics Data System (ADS)

It is widely assumed by policymakers and health professionals that the harmful health impacts of anthropogenic climate change will be partially offset by a decline in excess winter deaths (EWDs) in temperate countries, as winters warm. Recent UK government reports state that winter warming will decrease EWDs. Over the past few decades, however, the UK and other temperate countries have simultaneously experienced better housing, improved health care, higher incomes and greater awareness of the risks of cold. The link between winter temperatures and EWDs may therefore no longer be as strong as before. Here we report on the key drivers that underlie year-to-year variations in EWDs. We found that the association of year-to-year variation in EWDs with the number of cold days in winter ( <5 °C), evident until the mid 1970s, has disappeared, leaving only the incidence of influenza-like illnesses to explain any of the year-to-year variation in EWDs in the past decade. Although EWDs evidently do exist, winter cold severity no longer predicts the numbers affected. We conclude that no evidence exists that EWDs in England and Wales will fall if winters warm with climate change. These findings have important implications for climate change health adaptation policies.

Staddon, Philip L.; Montgomery, Hugh E.; Depledge, Michael H.

2014-03-01

17

Response of ocean ecosystems to climate warming  

NASA Astrophysics Data System (ADS)

We examine six different coupled climate model simulations to determine the ocean biological response to climate warming between the beginning of the industrial revolution and 2050. We use vertical velocity, maximum winter mixed layer depth, and sea ice cover to define six biomes. Climate warming leads to a contraction of the highly productive marginal sea ice biome by 42% in the Northern Hemisphere and 17% in the Southern Hemisphere, and leads to an expansion of the low productivity permanently stratified subtropical gyre biome by 4.0% in the Northern Hemisphere and 9.4% in the Southern Hemisphere. In between these, the subpolar gyre biome expands by 16% in the Northern Hemisphere and 7% in the Southern Hemisphere, and the seasonally stratified subtropical gyre contracts by 11% in both hemispheres. The low-latitude (mostly coastal) upwelling biome area changes only modestly. Vertical stratification increases, which would be expected to decrease nutrient supply everywhere, but increase the growing season length in high latitudes. We use satellite ocean color and climatological observations to develop an empirical model for predicting chlorophyll from the physical properties of the global warming simulations. Four features stand out in the response to global warming: (1) a drop in chlorophyll in the North Pacific due primarily to retreat of the marginal sea ice biome, (2) a tendency toward an increase in chlorophyll in the North Atlantic due to a complex combination of factors, (3) an increase in chlorophyll in the Southern Ocean due primarily to the retreat of and changes at the northern boundary of the marginal sea ice zone, and (4) a tendency toward a decrease in chlorophyll adjacent to the Antarctic continent due primarily to freshening within the marginal sea ice zone. We use three different primary production algorithms to estimate the response of primary production to climate warming based on our estimated chlorophyll concentrations. The three algorithms give a global increase in primary production of 0.7% at the low end to 8.1% at the high end, with very large regional differences. The main cause of both the response to warming and the variation between algorithms is the temperature sensitivity of the primary production algorithms. We also show results for the period between the industrial revolution and 2050 and 2090.

Sarmiento, J. L.; Slater, R.; Barber, R.; Bopp, L.; Doney, S. C.; Hirst, A. C.; Kleypas, J.; Matear, R.; Mikolajewicz, U.; Monfray, P.; Soldatov, V.; Spall, S. A.; Stouffer, R.

2004-09-01

18

Divergence of reproductive phenology under climate warming  

PubMed Central

Because the flowering and fruiting phenology of plants is sensitive to environmental cues such as temperature and moisture, climate change is likely to alter community-level patterns of reproductive phenology. Here we report a previously unreported phenomenon: experimental warming advanced flowering and fruiting phenology for species that began to flower before the peak of summer heat but delayed reproduction in species that started flowering after the peak temperature in a tallgrass prairie in North America. The warming-induced divergence of flowering and fruiting toward the two ends of the growing season resulted in a gap in the staggered progression of flowering and fruiting in the community during the middle of the season. A double precipitation treatment did not significantly affect flowering and fruiting phenology. Variation among species in the direction and magnitude of their response to warming caused compression and expansion of the reproductive periods of different species, changed the amount of overlap between the reproductive phases, and created possibilities for an altered selective environment to reshape communities in a future warmed world. PMID:17182748

Sherry, Rebecca A.; Zhou, Xuhui; Gu, Shiliang; Arnone, John A.; Schimel, David S.; Verburg, Paul S.; Wallace, Linda L.; Luo, Yiqi

2007-01-01

19

Is the climate warming or cooling? David R. Easterling1  

E-print Network

trend due to anthropogenic green- house gas forcing. Climate scientists pay little attentionIs the climate warming or cooling? David R. Easterling1 and Michael F. Wehner2 Received 18 February, blogs and articles in the media have claimed that the climate is no longer warming, and is now cooling

20

Lagging adaptation to warming climate in Arabidopsis thaliana  

PubMed Central

If climate change outpaces the rate of adaptive evolution within a site, populations previously well adapted to local conditions may decline or disappear, and banked seeds from those populations will be unsuitable for restoring them. However, if such adaptational lag has occurred, immigrants from historically warmer climates will outperform natives and may provide genetic potential for evolutionary rescue. We tested for lagging adaptation to warming climate using banked seeds of the annual weed Arabidopsis thaliana in common garden experiments in four sites across the species’ native European range: Valencia, Spain; Norwich, United Kingdom; Halle, Germany; and Oulu, Finland. Genotypes originating from geographic regions near the planting site had high relative fitness in each site, direct evidence for broad-scale geographic adaptation in this model species. However, genotypes originating in sites historically warmer than the planting site had higher average relative fitness than local genotypes in every site, especially at the northern range limit in Finland. This result suggests that local adaptive optima have shifted rapidly with recent warming across the species’ native range. Climatic optima also differed among seasonal germination cohorts within the Norwich site, suggesting that populations occurring where summer germination is common may have greater evolutionary potential to persist under future warming. If adaptational lag has occurred over just a few decades in banked seeds of an annual species, it may be an important consideration for managing longer-lived species, as well as for attempts to conserve threatened populations through ex situ preservation. PMID:24843140

Wilczek, Amity M.; Cooper, Martha D.; Korves, Tonia M.; Schmitt, Johanna

2014-01-01

21

Background: Global Warming, 2009 1. Unequivocally, the climate is warming. Natural systems are affected.  

E-print Network

Background: Global Warming, 2009 1. Unequivocally, the climate is warming. Natural systems are affected. 2. Very likely (>90% certainty), humans are causing most of the warming. 3. No single technology are very likely to impose net annual costs, which will increase over time as global temperatures increase

Minnesota, University of

22

Atmospheric superrotation in warm earth climates  

NASA Astrophysics Data System (ADS)

This thesis considers atmospheric superrotation, a state of westerly equatorial winds which must be maintained by up-gradient eddy momentum fluxes. Superrotation has appeared in simulations of warm climates that generate enhanced Madden-Julian Oscillation (MJO)-like variability. This led to hypotheses that the warmer atmospheres of the early Pliocene and Eocene may have been superrotating, and that the phenomenon may be relevant to future climate projections. To understand the MJO response to increases in temperature, I conduct aquaplanet simulations with a super-parameterized general circulation model. Between 29C and 35C, enhanced MJO variability causes a three-fold increase in equatorward eddy momentum fluxes and increasingly westerly equatorial winds. A composite moist static energy (MSE) budget shows that the MJO amplification is due to vertical advection over an MSE profile which steepens with increased SST. This steepening is a direct consequence of maintaining a moist adiabat over a warmer surface and suggests MJO amplification is fundamental to warming. This effect is then studied in a more realistic configuration using a coupled ocean-atmosphere model with continents and a seasonal cycle. Simulations are run with 1xCO2 and 4xCO2, and MJO activity is found to intensify in the warmer climate. Consistent with the aquaplanet results, the MSE budget identifies vertical advection over a steeper MSE profile as the primary cause. A positive feedback is then proposed, capable of driving abrupt transitions from a conventional circulation to a strongly superrotating one. Shallow water theory is used to show that as a mean westerly wind approaches the phase speed of free equatorial Rossby waves, the amplitude of a Rossby wave forced by fixed eddy heating will undergo a resonant amplification, along with its equatorward momentum flux. Idealized simulations with a numerical model demonstrate that the resonance and abrupt transitions can occur in the fully 3D primitive equations. Finally, I consider an explanation for large warm anomalies at mid-latitude coastal upwelling sites during the Pliocene. Simulations run with two reconstructions of Pliocene SST show reductions in upwelling-favorable winds around all four mid-latitude sites, suggesting that the coastal anomalies could result from reductions in upwelling forced by the large-scale SST pattern.

Arnold, Nathan Patrick

23

Early Eocene climate warming increased petroleum production  

NASA Astrophysics Data System (ADS)

From the late Paleocene, about 58 million years ago, to the early Eocene, about 51 million years ago, Earth's surface temperatures warmed by about 5°-10°C. Also in the early Eocene, there was an increase of carbon-13-depleted carbon in the oceans that cannot be accounted for by changes in carbon cycling at the surface. To better understand the source of that carbon, Kroeger and Funnell modeled the thermal evolution of four sedimentary basins in the southwestern Pacific Ocean. The authors show that the rising surface temperatures of the early Eocene eventually led to warming of the sedimentary beds deep beneath the surface. Petroleum can be produced at only a certain range of temperatures; rising temperatures at greater depths would bring more potential source rocks into temperature conditions under which oil and gas can be produced and released.

Balcerak, Ernie

2012-04-01

24

Regional news portrayals of global warming and climate change  

Microsoft Academic Search

In this study we utilize content analysis techniques to examine how the issue of global warming and climate change has been characterized during the period of 1992 through 2005 by the Houston Chronicle—the largest regional newspaper in the Texas coastal region. A total of 795 global warming and climate change news articles from the Houston Chronicle are collected, coded and

Xinsheng Liu; Arnold Vedlitz; Letitia Alston

2008-01-01

25

How to preserve the tundra in a warming climate?  

NASA Astrophysics Data System (ADS)

The warming climate of the polar regions may change much of the current arctic-alpine tundra to forest or dense scrubland. This modification requires adaptation by traditional livelihoods such as reindeer herding, which relies on diverse, seasonal pasturelands. Vegetation change may also trigger positive warming feedbacks, where more abundant forest-scrub vegetation will decrease the global albedo. NCoE Tundra team investigates the complex climate-animal-plant interaction of the tundra ecosystem and aim to unravel the capability of herbivorous mammals to control the expansion of woody vegetation. Our interdisciplinary approach involves several work packages, whose results will be summarised in the presentation. In the ecological WPs, we study the dynamics of the natural food chains involving small herbivorous and the impacts of reindeer on the vegetation and the population dynamics of those arctic-alpine plants, which are most likely to become threatened in a warmer climate. Our study demonstrates the potential of a relatively sparse reindeer stocks (2-5 heads per km2) together with natural populations of arvicoline rodents to prevent the expansion of erect woody plants at the arctic-alpine timberline. In the climatic WPs we study the impact of grazing-dependent vegetation differences on the fraction of solar energy converted to heat. In the socio-economic WPs, we study the conditions for maintaining the economic and cultural viability of reindeer herding while managing the land use so that the arctic-alpine biota would be preserved.

Käyhkö, Jukka

2014-05-01

26

Contrasting population changes in sympatric penguin species in association with climate warming  

Microsoft Academic Search

Climate warming and associated sea ice reductions in Antarctica have modified habitat conditions for some species. These include the congeneric Adelie, chinstrap and gentoo penguins, which now demonstrate remarkable population responses to regional warm- ing. However, inconsistencies in the direction of population changes between species at different study sites complicate the understanding of causal processes. Here, we show that at

E. J. MU R PHY

2006-01-01

27

Modelling middle pliocene warm climates of the USA  

USGS Publications Warehouse

The middle Pliocene warm period represents a unique time slice in which to model and understand climatic processes operating under a warm climatic regime. Palaeoclimatic model simulations, focussed on the United States of America (USA), for the middle Pliocene (ca 3 Ma) were generated using the USGS PRISM2 2?? ?? 2?? data set of boundary conditions and the UK Meteorological Office's HadAMS General Circulation Model (GCM). Model results suggest that conditions in the USA during the middle Pliocene can be characterised as annually warmer (by 2?? to 4??C), less seasonal, wetter (by a maximum of 4 to 8 mm/day) and with an absence of freezing winters over the central and southern Great Plains. A sensitivity experiment suggests that the main forcing mechanisms for surface temperature changes in near coastal areas are the imposed Pliocene sea surface temperatures (SST's). In interior regions, reduced Northern Hemisphere terrestrial ice, combined with less snow cover and a reduction in the elevation of the western cordillera of North America, generate atmospheric circulation changes and positive albedo feedbacks that raise surface temperatures. A complex set of climatic feedback mechanisms cause an enhancement of the hydrological cycle magnifying the moisture bearing westerly wind belt during the winter season (Dec., Jan., Feb.). Predictions produced by the model are in broad agreement with available geological evidence. However, the GCM appears to underestimate precipitation levels in the interior and central regions of the southern USA. Copyright: Palaeontological Association, 22 June 2001.

Haywood, A.M.; Valdes, P.J.; Sellwood, B.W.; Kaplan, J.O.; Dowsett, H.J.

2001-01-01

28

Ocean biogeochemistry in the warm climate of the late Paleocene  

NASA Astrophysics Data System (ADS)

The late Paleocene is characterized by warm and stable climatic conditions that served as the background climate for the Paleocene-Eocene Thermal Maximum (PETM, ~55 million years ago). With respect to feedback processes in the carbon cycle, the ocean biogeochemical background state is of major importance for projecting the climatic response to a carbon perturbation related to the PETM. Therefore, we use the Hamburg Ocean Carbon Cycle model (HAMOCC), embedded in the ocean general circulation model of the Max Planck Institute for Meteorology, MPIOM, to constrain the ocean biogeochemistry of the late Paleocene. We focus on the evaluation of modeled spatial and vertical distributions of the ocean carbon cycle parameters in a long-term warm steady-state ocean, based on a 560 ppm CO2 atmosphere. Model results are discussed in the context of available proxy data and simulations of pre-industrial conditions. Our results illustrate that ocean biogeochemistry is shaped by the warm and sluggish ocean state of the late Paleocene. Primary production is slightly reduced in comparison to the present day; it is intensified along the Equator, especially in the Atlantic. This enhances remineralization of organic matter, resulting in strong oxygen minimum zones and CaCO3 dissolution in intermediate waters. We show that an equilibrium CO2 exchange without increasing total alkalinity concentrations above today's values is achieved. However, consistent with the higher atmospheric CO2, the surface ocean pH and the saturation state with respect to CaCO3 are lower than today. Our results indicate that, under such conditions, the surface ocean carbonate chemistry is expected to be more sensitive to a carbon perturbation (i.e., the PETM) due to lower CO32- concentration, whereas the deep ocean calcite sediments would be less vulnerable to dissolution due to the vertically stratified ocean.

Heinze, M.; Ilyina, T.

2015-01-01

29

Adapting California's water system to warm vs. dry climates  

E-print Network

Adapting California's water system to warm vs. dry climates Christina R. Connell-Buck & Josué adaptations. Least-cost water supply system adaptation is explored for two climate scenarios: 1) warmer adaptations. A warmer climate alone reduces water deliveries and increases costs, but much less than a warmer

Pasternack, Gregory B.

30

CLIMATE WARMING AND WATER MANAGEMENT ADAPTATION FOR CALIFORNIA  

E-print Network

CLIMATE WARMING AND WATER MANAGEMENT ADAPTATION FOR CALIFORNIA STACY K. TANAKA, TINGJU ZHU, JAY R of California's water supply system to adapt to long-term climatic and demo- graphic changes is examined. Two to adapt to significant changes in climate and population. More specifically, California's water supply

Pasternack, Gregory B.

31

Soil respiration under climate warming: differential response of heterotrophic and autotrophic respiration.  

PubMed

Despite decades of research, how climate warming alters the global flux of soil respiration is still poorly characterized. Here, we use meta-analysis to synthesize 202 soil respiration datasets from 50 ecosystem warming experiments across multiple terrestrial ecosystems. We found that, on average, warming by 2 °C increased soil respiration by 12% during the early warming years, but warming-induced drought partially offset this effect. More significantly, the two components of soil respiration, heterotrophic respiration and autotrophic respiration showed distinct responses. The warming effect on autotrophic respiration was not statistically detectable during the early warming years, but nonetheless decreased with treatment duration. In contrast, warming by 2 °C increased heterotrophic respiration by an average of 21%, and this stimulation remained stable over the warming duration. This result challenged the assumption that microbial activity would acclimate to the rising temperature. Together, our findings demonstrate that distinguishing heterotrophic respiration and autotrophic respiration would allow us better understand and predict the long-term response of soil respiration to warming. The dependence of soil respiration on soil moisture condition also underscores the importance of incorporating warming-induced soil hydrological changes when modeling soil respiration under climate change. PMID:24771521

Wang, Xin; Liu, Lingli; Piao, Shilong; Janssens, Ivan A; Tang, Jianwu; Liu, Weixing; Chi, Yonggang; Wang, Jing; Xu, Shan

2014-10-01

32

Why tropical forest lizards are vulnerable to climate warming  

PubMed Central

Biological impacts of climate warming are predicted to increase with latitude, paralleling increases in warming. However, the magnitude of impacts depends not only on the degree of warming but also on the number of species at risk, their physiological sensitivity to warming and their options for behavioural and physiological compensation. Lizards are useful for evaluating risks of warming because their thermal biology is well studied. We conducted macrophysiological analyses of diurnal lizards from diverse latitudes plus focal species analyses of Puerto Rican Anolis and Sphaerodactyus. Although tropical lowland lizards live in environments that are warm all year, macrophysiological analyses indicate that some tropical lineages (thermoconformers that live in forests) are active at low body temperature and are intolerant of warm temperatures. Focal species analyses show that some tropical forest lizards were already experiencing stressful body temperatures in summer when studied several decades ago. Simulations suggest that warming will not only further depress their physiological performance in summer, but will also enable warm-adapted, open-habitat competitors and predators to invade forests. Forest lizards are key components of tropical ecosystems, but appear vulnerable to the cascading physiological and ecological effects of climate warming, even though rates of tropical warming may be relatively low. PMID:19324762

Huey, Raymond B.; Deutsch, Curtis A.; Tewksbury, Joshua J.; Vitt, Laurie J.; Hertz, Paul E.; Álvarez Pérez, Héctor J.; Garland, Theodore

2009-01-01

33

The Climate Policy Narrative for a Dangerously Warming World  

SciTech Connect

It is time to acknowledge that global average temperatures will likely rise above the 2 C policy target and consider how that deeply troubling prospect should affect priorities for communicating and managing the risks of a dangerously warming climate.

Sanford, Todd [Union of Concerned Scientists] [Union of Concerned Scientists; Frumhoff, Peter [Union of Concerned Scientists] [Union of Concerned Scientists; Luers, Amy [Skoll Global Threats Fund] [Skoll Global Threats Fund; Gulledge, Jay [ORNL] [ORNL

2014-01-01

34

The Impact of Boreal Forest Fire on Climate Warming  

E-print Network

fire, integrating the effects of greenhouse gases, aerosols,and the effects from the remaining greenhouse gases in thegreenhouse gases emitted by fire contribute to climate warming, understanding the net effect

2006-01-01

35

Climate Warming and Disease Risks for Terrestrial and Marine Biota  

Microsoft Academic Search

Infectious diseases can cause rapid population declines or species extinctions. Many pathogens of terrestrial and marine taxa are sensitive to temperature, rainfall, and humidity, creating synergisms that could affect biodiversity. Climate warming can increase pathogen development and survival rates, disease transmission, and host susceptibility. Although most host-parasite systems are predicted to experience more frequent or severe disease impacts with warming,

C. Drew Harvell; Charles E. Mitchell; Jessica R. Ward; Sonia Altizer; Andrew P. Dobson; Richard S. Ostfeld; Michael D. Samuel

2002-01-01

36

Estimating the Potential for Adaptation of Corals to Climate Warming  

Microsoft Academic Search

The persistence of tropical coral reefs is threatened by rapidly increasing climate warming, causing a functional breakdown of the obligate symbiosis between corals and their algal photosymbionts (Symbiodinium) through a process known as coral bleaching. Yet the potential of the coral-algal symbiosis to genetically adapt in an evolutionary sense to warming oceans is unknown. Using a quantitative genetics approach, we

Nikolaus B. M. Császár; Peter J. Ralph; Richard Frankham; Ray Berkelmans; Madeleine J. H. van Oppen; Robert Desalle

2010-01-01

37

The capacity to cope with climate warming declines from temperate to tropical latitudes in two widely distributed Eucalyptus species.  

PubMed

As rapid climate warming creates a mismatch between forest trees and their home environment, the ability of trees to cope with warming depends on their capacity to physiologically adjust to higher temperatures. In widespread species, individual trees in cooler home climates are hypothesized to more successfully acclimate to warming than their counterparts in warmer climates that may approach thermal limits. We tested this prediction with a climate-shift experiment in widely distributed Eucalyptus tereticornis and E. grandis using provenances originating along a ~2500 km latitudinal transect (15.5-38.0°S) in eastern Australia. We grew 21 provenances in conditions approximating summer temperatures at seed origin and warmed temperatures (+3.5 °C) using a series of climate-controlled glasshouse bays. The effects of +3.5 °C warming strongly depended on home climate. Cool-origin provenances responded to warming through an increase in photosynthetic capacity and total leaf area, leading to enhanced growth of 20-60%. Warm-origin provenances, however, responded to warming through a reduction in photosynthetic capacity and total leaf area, leading to reduced growth of approximately 10%. These results suggest that there is predictable intraspecific variation in the capacity of trees to respond to warming; cool-origin taxa are likely to benefit from warming, while warm-origin taxa may be negatively affected. PMID:25378195

Drake, John E; Aspinwall, Michael J; Pfautsch, Sebastian; Rymer, Paul D; Reich, Peter B; Smith, Renee A; Crous, Kristine Y; Tissue, David T; Ghannoum, Oula; Tjoelker, Mark G

2015-01-01

38

Global warming and Arctic climate. Raymond S. Bradley  

E-print Network

Global warming and Arctic climate. Raymond S. Bradley Climate System Research Center University of Massachusetts Amherst #12;How have global temperatures changed & why? 1. Average instrumental records from around the world; express all as anomalies from 1961-90 average #12;#12;Overall trend is upward ("global

Mountziaris, T. J.

39

Simulated increase of hurricane intensities in a CO{sub 2}-warmed climate  

SciTech Connect

Hurricanes can inflict catastrophic property damage and loss of human life. Thus, it is important to determine how the character of these powerful storms could change in response to greenhouse gas-induced global warming. The impact of climate warming on hurricane intensities was investigated with a regional, high-resolution, hurricane prediction model. In a case study, 51 western Pacific storm cases under present-day climate conditions were compared with 51 storm cases under high-CO{sub 2} conditions. More idealized experiments were also performed. The large-scale initial conditions were derived from a global climate model. For a sea surface temperature warming of about 2.2{degree}C, the simulations yielded hurricanes that were more intense by 3 to 7 meters per second (5 to 12 percent) for wind speed and 7 to 20 millibars for central surface pressure. 26 refs., 4 figs.

Knutson, T.R.; Tuleya, R.E.; Kurihara, Y. [National Oceanic and Atmospheric Administration, Princeton, NJ (United States)] [National Oceanic and Atmospheric Administration, Princeton, NJ (United States)

1998-02-13

40

Peatland Carbon Dynamics in Alaska During Past Warm Climates  

NASA Astrophysics Data System (ADS)

Peatlands represent a large belowground carbon (C) pool in the biosphere. However, how peatland C sequestration capacity varies with changes in climate and climate-induced disturbance is still poorly understood and debated. Here we summarize results from Alaskan peatlands to document how peat C accumulation has responded to past warm climate intervals. We find that the greatest C accumulation rates at sites from the Kenai Peninsula to the North Slope occurred during the Holocene thermal maximum (HTM) in the early Holocene. This time period also corresponds with explosive formation and expansion of new peatlands on the landscape across Alaska. In addition, we note that many peatlands that existed during the earlier Holocene on the North Slope have disappeared and are presently covered by mineral soils under tundra or sandy deposits. During the Medieval Climate Anomaly (MCA) around 1000-500 years ago, several peatlands in Alaska show high rates of C accumulation when compared to the period before the MCA during the Neoglacial or the following Little Ice Age period. Altogether, our results indicate that the Alaskan landscape was very different during the last 10,000 years and that peatlands can rapidly accumulate C under warm climatic conditions. We speculate that warmth-stimulated increase in plant production surpasses increase in peat decomposition during the early Holocene, and potentially also during the MCA. Other factors that might have contributed to rapid peat accumulation during the early Holocene include increased summer sunlight, lowered sea levels, and decreased sea-ice cover/duration. Summer insolation was ca. 8% higher than today during the early Holocene due to orbital variations, which likely promoted plant productivity by increasing growing seasons sunlight. Furthermore, lower sea levels and exposed shallow continental shelves in the Beaufort Sea (Arctic Ocean) would have made the present-day Arctic Coastal Plain more continental, with warmer summers and colder winters, also reducing non-growing season decomposition. Reduced summer sea ice cover would also mediate and increase summer temperatures on the North Slope. Overall, our results show that, contrary to conventional wisdom, cool and wet climates such as those that characterized the Neoglacial period may result in peatland flooding (too much water), thereby limiting peat accumulation in these wet and cold regions. If the observations from northern Alaska are also applicable to other high-latitude regions with possible 'disappeared peatlands', our findings have important implications for understanding the role of peatlands in the global C cycle in the past and future.

Yu, Z.; Cleary, K.; Massa, C.; Hunt, S. J.; Klein, E. S.; Loisel, J.

2013-12-01

41

Global Warming What is Climate? Ocean's Role in Climate Change Uncertainty Quantification, the Next Frontier The Role Played by Oceans in Climate  

E-print Network

Global Warming What is Climate? Ocean's Role in Climate Change Uncertainty Quantification, the Next Department University of Arizona October 11, 2008 #12;Global Warming What is Climate? Ocean's Role in Climate, Undergraduate Students: 2. UQGQG #12;Global Warming What is Climate? Ocean's Role in Climate Change Uncertainty

Restrepo, Juan M.

42

Alien plant species favoured over congeneric natives under experimental climate warming in temperate Belgian climate  

Microsoft Academic Search

Climate warming and biological invasions by alien species are two key factors threatening the world’s biodiversity. To date,\\u000a their impact has largely been studied independently, and knowledge on whether climate warming will promote invasions relies\\u000a strongly on bioclimatic models. We therefore set up a study to experimentally compare responses to warming in native and alien\\u000a plant species. Ten congeneric species pairs were

M. Verlinden; I. Nijs

2010-01-01

43

Hydrological response to climate warming: The Upper Feather River Watershed  

NASA Astrophysics Data System (ADS)

SummaryThe hydrological response and sensitivity to climate warming of a snow-dominated watershed, the Upper Feather River Basin (UFRB) in Northern California, were evaluated and quantified using observed changes, detrending, and specified temperature-based sensitivity simulations. The non-stationarity in historical data was detected with trend analysis and the warming trends in historical forcing data were removed by detrending. The physically-based and spatially-distributed Precipitation-Runoff Modeling System (PRMS) model was used to force uniform climate warming (+1 °C to +4 °C) to investigate hydrologic sensitivity to temperature increase. Six Global Climate Models (GCMs) with two IPCC Special Report on Emissions Scenarios (SRES), A2 and B1, were selected to represent a range of climate change projections. These projected changes were then applied to the detrended historical forcing data to simulate climate change effects in a detrended, quasi-stationary setting. The results indicate that: (1) historical annual precipitation and streamflow have no trends, but air temperature and seasonal streamflow have statistically significant trends. (2) By detrending temperature, the strong trends in seasonal streamflow are virtually eliminated. (3) Hydrologic Sensitivity to climate warming includes small changes in annual streamflow and actual evapotranspiration, significant changes in streamflow timing and increased frequency and magnitude in extreme flows. (4) All GCM projections lead to negative impact on water supply.

Huang, Guobiao; Kadir, Tariq; Chung, Francis

2012-03-01

44

The Great Season Climatic Oscillation and the Global Warming  

E-print Network

The present earth warming up is often explained by the atmosphere gas greenhouse effect. This explanation is in contradiction with the thermodynamics second law. The warming up by greenhouse effect is quite improbable. It is cloud reflection that gives to the earth s ground its 15 degres C mean temperature. Since the reflection of the radiation by gases is negligible, the role of the atmosphere greenhouse gases in the earth warming up by earth radiation reflection loses its importance. We think that natural climatic oscillations contribute more to earth climatic disturbances. The oscillation that we hypothesize to exist has a long period (800 to 1000 years). The glacier melting and regeneration cycles lead to variations in the cold region ocean water density and thermal conductibility according to their salinity. These variations lead one to think about a macro climate oscillating between maximum hot and minimum cold temperatures. This oscillation is materialized by the passages of the planet through hot, mil...

Boucenna, Ahmed

2008-01-01

45

The case for a wet, warm climate on early Mars.  

PubMed

Theoretical arguments are presented in support of the idea that Mars possessed a dense CO2 atmosphere and a wet, warm climate early in its history. Calculations with a one-dimensional radiative-convective climate model indicate that CO2 pressures between 1 and 5 bars would have been required to keep the surface temperature above the freezing point of water early in the planet's history. The higher value corresponds to globally and orbitally averaged conditions and a 30% reduction in solar luminosity; the lower value corresponds to conditions at the equator during perihelion at times of high orbital eccentricity and the same reduced solar luminosity. The plausibility of such a CO2 greenhouse is tested by formulating a simple model of the CO2 geochemical cycle on early Mars. By appropriately scaling the rate of silicate weathering on present Earth, we estimate a weathering time constant of the order of several times 10(7) years for early Mars. Thus, a dense atmosphere could have persisted for a geologically significant time period (approximately 10(9) years) only if atmospheric CO2 was being continuously resupplied. The most likely mechanism by which this might have been accomplished is the thermal decomposition of carbonate rocks induced directly and indirectly (through burial) by intense, global-scale volcanism. For plausible values of the early heat flux, the recycling time constant is also of the order of several times 10(7) years. The amount of CO2 dissolved in standing bodies of water was probably small; thus, the total surficial CO2 inventory required to maintain these conditions was approximately 2 to 10 bars. The amount of CO2 in Mars' atmosphere would eventually have dwindled, and the climate cooled, as the planet's internal heat engine ran down. A test for this theory will be provided by spectroscopic searches for carbonates in Mars' crust. PMID:11539035

Pollack, J B; Kasting, J F; Richardson, S M; Poliakoff, K

1987-01-01

46

Geoengineering: Direct Mitigation of Climate Warming  

EPA Science Inventory

For Frank Princiotta?s book, Global Climate Change?The Technology Challenge With the concentrations of atmospheric greenhouse gases (GHGs) rising to levels unprecedented in the current glacial epoch, the earth?s climate system appears to be rapidly shifting into a warmer regime....

47

Ancient tropical climates warm San Francisco gathering  

SciTech Connect

Climate records preserved in the Greenland ice sheet got a lot of the attention at the fall meeting of the American Geophysical Union (AGU) in San Francisco last month, but ancient tropical records were a rival attraction. In talks scattered in unrelated sessions, researchers reported a possible role for the tropics in driving the last ice age, a link between high latitudes and the tropics that may have redirected human evolution, and a tropical climate periodicity that may fill a gap in the understanding of climate variability.

Kerr, R.A.

1994-01-14

48

Modelling the response of glaciers to climate warming  

Microsoft Academic Search

Dynamic ice-flow models for 12 glaciers and ice caps have been forced with various climate change scenarios. The volume of\\u000a this sample spans three orders of magnitude. Six climate scenarios were considered: from 1990 onwards linear warming rates\\u000a of 0.01, 0.02 and 0.04?K a-1, with and without concurrent changes in precipitation. The models, calibrated against the historic record of glacier

J. Oerlemans; B. Anderson; A. Hubbard; P. Huybrechts; T. Jóhannesson; W. H. Knap; M. J. Schmeits; A. P. Stroeven; J. Wallinga; Z. Zuo

1998-01-01

49

Global Warming Potentials: 1. Climatic Implications of Emissions Reductions  

Microsoft Academic Search

The use of Global Warming Potentials (GWPs) to calculate ‘equivalent’ carbon dioxide emissions reductions in the climate change context is examined. We find that GWPs are accurate only for short time horizons. Over long time horizons their use implicitly leads to tradeoffs between near-term and long-term climate change. For one of the most policy-relevant cases, comparing reductions in methane and

Steven J. Smith; M. L. Wigley

2000-01-01

50

Projected changes of snow conditions and avalanche activity in a warming climate: a case study in the French Alps over the 2020-2050 and 2070-2100 periods  

NASA Astrophysics Data System (ADS)

Projecting changes in snow cover due to climate warming is important for many societal issues, including adaptation of avalanche risk mitigation strategies. Efficient modeling of future snow cover requires high resolution to properly resolve the topography. Here, we detail results obtained through statistical downscaling techniques allowing simulations of future snowpack conditions for the mid- and late 21st century in the French Alps under three climate change scenarios. Refined statistical descriptions of snowpack characteristics are provided with regards to a 1960-1990 reference period, including latitudinal, altitudinal and seasonal gradients. These results are then used to feed a statistical model of avalanche activity-snow conditions-meteorological conditions relationships, so as to produce the first prognoses at annual/seasonal time scales of future natural avalanche activity eventually based on past observations. The resulting statistical indicators are fundamental for the mountain economy in terms of changes anticipation. At all considered spatio-temporal scales, whereas precipitations are expected to remain quite stationary, temperature increase interacting with topography will control snow-related variables, for instance the rate of decrease of total and dry snow depths, and the successive increase/decrease of the wet snow pack. Overall, with regards to the reference period, changes are strong for the end of the 21st century, but already significant for the mid-century. Changes in winter are somewhat less important than in spring, but wet snow conditions will appear at high elevations earlier in the season. For a given altitude, the Southern French Alps will not be significantly more affected than the Northern French Alps, so that the snowpack characteristics will be preserved more lately in the southern massifs of higher mean altitude. Regarding avalanche activity, a general -20-30% decrease and interannual variability is forecasted, relatively strong compared to snow and meteorological parameters changes. This decrease is amplified in spring and at low altitude. In contrast, an increase of avalanche activity is expected in winter at high altitude because of earlier wet snow avalanches triggers, at least as long as a minimal snow cover will be present. Comparison with the outputs of the deterministic avalanche hazard model MEPRA shows generally consistent results but suggests that, even if the frequency of winters with high avalanche activity will clearly decrease, the decreasing trend may be less strong and smooth than suggested by the changes in snowpack characteristics. This important point for risk assessment pleads for further work focusing on shorter time scales. Finally, small differences between different climate change scenarios show the robustness of the predicted avalanche activity changes.

Castebrunet, H.; Eckert, N.; Giraud, G.; Durand, Y.; Morin, S.

2014-01-01

51

Climate warming and disease risks for terrestrial and marine biota  

USGS Publications Warehouse

Infectious diseases can cause rapid population declines or species extinctions. Many pathogens of terrestrial and marine taxa are sensitive to temperature, rainfall, and humidity, creating synergisms that could affect biodiversity. Climate warming can increase pathogen development and survival rates, disease transmission, and host susceptibility. Although most host-parasite systems are predicted to experience more frequent or severe disease impacts with warming, a subset of pathogens might decline with warming, releasing hosts from disease. Recently, changes in El Niño–Southern Oscillation events have had a detectable influence on marine and terrestrial pathogens, including coral diseases, oyster pathogens, crop pathogens, Rift Valley fever, and human cholera. To improve our ability to predict epidemics in wild populations, it will be necessary to separate the independent and interactive effects of multiple climate drivers on disease impact.

Harvell, C.D.; Mitchell, C.E.; Ward, J.R.; Altizer, S.; Dobson, A.P.; Ostfeld, R.S.; Samuel, M.D.

2002-01-01

52

Lightning Strikes Predicted to Increase as Climate Warms  

NASA Astrophysics Data System (ADS)

By the end of the 21st century, the frequency of lightning strikes in the United States may increase by 50% because of climate warming, up from an average 25 million lightning strikes per year, a paper published in the 13 November issue of Science reports.

Wendel, JoAnna

2014-11-01

53

Seventh Grade Students' Conceptions of Global Warming and Climate Change  

ERIC Educational Resources Information Center

The purpose of this study was to investigate seventh grade students' conceptions of global warming and climate change. The study was descriptive in nature and involved the collection of qualitative data from 91 seventh grade students from three different schools in the Midwest, USA. An open response and draw and explain assessment instrument was…

Shepardson, Daniel P.; Niyogi, Dev; Choi, Soyoung; Charusombat, Umarporn

2009-01-01

54

Climate Science in a Nutshell: Evidence of a Warming Planet  

NSDL National Science Digital Library

This video is part of the Climate Science in a Nutshell series. This short, animated video looks at evidence of a rapidly warming planet. It discusses how air bubbles in ice cores can be used to estimate Earth's average air temperature for thousands of years and how direct measurements document air temperatures from 1880.

Planet Nutshell

55

Possible Impacts of Climatic Warming on Polar Bears  

Microsoft Academic Search

If climatic warming occurs, the first impacts on polar bears (Ursus maritirnus) will be felt at the southern limits of their distribution, such as in James and Hudson bays, where the whole population is already forced to fast for approximately four months when the sea ice melts during the summer. Prolonging the ice-free period will increase nutritional stress on this

ANDREW E. DEROCHER

1993-01-01

56

Earth's Warming Climate: Are We Responsible?  

NSDL National Science Digital Library

This tutorial provides the evidence that the amount of CO² in the atmosphere has not been as high as it is currently for nearly half a million years and that this increase corresponds with data that human activity is responsible. Learners examine scientific data showing increases in both atmospheric becomes CO² and the Earth's average temperature and analyze changes in atmospheric concentration of CO² over time. They reflect on some of the barriers involved in teaching global climate change and how using data in the classroom may be used to overcome those barriers. Multimedia resources such as video clips, a data visualization exercise featuring digital resources on climate.nasa.gov, and an interview with NASA climate scientist, Dr. Gavin Schmidt, are included. This is the second of ten self-paced professional development modules providing opportunities for teachers to learn about climate change through first-hand data exploration. Lesson plans for middle and high school students, descriptions of data collection instruments, glossary links to vocabulary are included.

2012-10-18

57

Polar Bears in a Warming Climate1  

Microsoft Academic Search

SYNOPSIS. Polar bears (Ursus maritimus) live throughout the ice-covered waters of the circumpolar Arctic, particularly in near shore annual ice over the continental shelf where biological productivity is highest. However, to a large degree under scenarios predicted by climate change models, these preferred sea ice habitats will be substantially altered. Spatial and temporal sea ice changes will lead to shifts

ANDREW E. DEROCHER; J. LUNN; IAN STIRLING

2004-01-01

58

Divergent tree growth response to recent climatic warming, Lake Clark National Park and Preserve, Alaska  

NASA Astrophysics Data System (ADS)

Many dendroclimatic studies have been conducted in Alaska to understand recent climate changes, identify past and current warming trends, and determine how climate change may influence ecosystems. Four new white spruce (Picea glauca [Moench] Voss) ring-width chronologies from four sites along a 30 kilometer north-south transect in the Lake Clark National Park and Preserve on the Alaskan Peninsula span a common interval from AD 1769 to 2003. Two sites show an internally consistent positive growth response to increasing April-July temperatures after 1950. The two other sites each contain two subpopulations showing varying growth responses. One subpopulation diverges from historical temperature data after 1950 and one shows increased growth consistent with warming or exceeds expected growth increases. The growth decline may be due to temperature-induced drought stress that acts on some trees. Unprecedented climatic changes are triggering diverse growth responses between and within study sites that may greatly complicate dendroclimatic reconstructions of past climate conditions.

Driscoll, William W.; Wiles, Gregory C.; D'Arrigo, Rosanne D.; Wilmking, Martin

2005-10-01

59

Geoengineering: Direct Mitigation of Climate Warming  

Microsoft Academic Search

\\u000a With the concentrations of atmospheric greenhouse gases (GHGs) rising to levels unprecedented in the current glacial epoch,\\u000a the earth’s climate system appears to be rapidly shifting into a warmer regime. Many in the international science and policy\\u000a communities fear that the fundamental changes in human behavior, and in the global economy, that will be required to meaningfully\\u000a reduce GHG emissions

Brooke L. Hemming; Gayle S. W. Hagler

60

Efficient Biological Nitrogen Fixation Under Warming Climates  

Microsoft Academic Search

\\u000a Nitrogen fixation (NF) in legumes results from their symbiotic interaction with soil bacteria called rhizobia to form nitrogen\\u000a fixing root nodules.The reduction of atmospheric nitrogen (N2) to ammonium by rhizobia is an important activity making N available for agricultural soils. Drought is one of the most common\\u000a stress factors affecting legume yields worldwide. Given the climatic trends viz a viz

F. Kantar; B. G. Shivakumar; C. Arrese-Igor; F. Y. Hafeez; E. M. González; A. Imran; E. Larrainzar

61

Climate and tourism in the Black Forest during the warm season  

NASA Astrophysics Data System (ADS)

Climate, climate change and tourism all interact. Part of the public discussion about climate change focusses on the tourism sector, with direct and indirect impacts being of equally high relevance. Climate and tourism are closely linked. Thus, climate is a very decisive factor in choices both of destination and of type of journey (active holidays, wellness, and city tours) in the tourism sector. However, whether choices about destinations or types of trip will alter with climate change is difficult to predict. Future climates can be simulated and projected, and the tendencies of climate parameters can be estimated using global and regional climate models. In this paper, the focus is on climate change in the mountainous regions of southwest Germany - the Black Forest. The Black Forest is one of the low mountain ranges where both winter and summer tourism are vulnerable to climate change due to its southern location; the strongest climatic changes are expected in areas covering the south and southwest of Germany. Moreover, as the choice of destination is highly dependent on good weather, a climatic assessment for tourism is essential. Thus, the aim of this study was to estimate climatic changes in mountainous regions during summer, especially for tourism and recreation. The assessment method was based on human-biometeorology as well as tourism-climatologic approaches. Regional climate simulations based on the regional climate model REMO were used for tourism-related climatic analyses. Emission scenarios A1B and B1 were considered for the time period 2021 to 2050, compared to the 30-year base period of 1971-2000, particularly for the warm period of the year, defined here as the months of March-November. In this study, we quantified the frequency, but not the means, of climate parameters. The study results show that global and regional warming is reflected in an increase in annual mean air temperature, especially in autumn. Changes in the spring show a slight negative trend, which is in line with the trend of a decrease in physiologically equivalent temperature as well as in thermal comfort conditions. Due to the rising air temperature, heat stress as well as sultry conditions are projected to become more frequent, affecting human health and recreation, especially at lower lying altitudes. The tops of the mountains and higher elevated areas still have the advantage of offering comfortable climatic conditions.

Endler, Christina; Matzarakis, Andreas

2011-03-01

62

Insects Overshoot the Expected Upslope Shift Caused by Climate Warming  

PubMed Central

Along elevational gradients, climate warming may lead to an upslope shift of the lower and upper range margin of organisms. A recent meta-analysis concluded that these shifts are species specific and considerably differ among taxonomic lineages. We used the opportunity to compare upper range margins of five lineages (plants, beetles, flies, hymenoptera, and birds) between 1902–1904 and 2006–2007 within one region (Bavarian Forest, Central Europe). Based on the increase in the regional mean annual temperature during this period and the regional lapse rate, the upslope shift is expected to be between 51 and 201 m. Averaged across species within lineages, the range margin of all animal lineages shifted upslope, but that of plants did not. For animals, the observed shifts were probably due to shifts in temperature and not to changes in habitat conditions. The range margin of plants is therefore apparently not constrained by temperature, a result contrasting recent findings. The mean shift of birds (165 m) was within the predicted range and consistent with a recent global meta-analysis. However, the upslope shift of the three insect lineages (>260 m) exceeded the expected shift even after considering several sources of uncertainty, which indicated a non-linear response to temperature. Our analysis demonstrated broad differences among lineages in their response to climate change even within one region. Furthermore, on the considered scale, the response of ectothermic animals was not consistent with expectations based on shifts in the mean annual temperature. Irrespective of the reasons for the overshooting of the response of the insects, these shifts lead to reorganizations in the composition of assemblages with consequences for ecosystem processes. PMID:23762439

Bässler, Claus; Hothorn, Torsten; Brandl, Roland; Müller, Jörg

2013-01-01

63

Warming Experiments Underpredict Plant Phenological Responses to Climate Change  

NASA Technical Reports Server (NTRS)

Warming experiments are increasingly relied on to estimate plant responses to global climate change. For experiments to provide meaningful predictions of future responses, they should reflect the empirical record of responses to temperature variability and recent warming, including advances in the timing of flowering and leafing. We compared phenology (the timing of recurring life history events) in observational studies and warming experiments spanning four continents and 1,634 plant species using a common measure of temperature sensitivity (change in days per degree Celsius). We show that warming experiments underpredict advances in the timing of flowering and leafing by 8.5-fold and 4.0-fold, respectively, compared with long-term observations. For species that were common to both study types, the experimental results did not match the observational data in sign or magnitude. The observational data also showed that species that flower earliest in the spring have the highest temperature sensitivities, but this trend was not reflected in the experimental data. These significant mismatches seem to be unrelated to the study length or to the degree of manipulated warming in experiments. The discrepancy between experiments and observations, however, could arise from complex interactions among multiple drivers in the observational data, or it could arise from remediable artefacts in the experiments that result in lower irradiance and drier soils, thus dampening the phenological responses to manipulated warming. Our results introduce uncertainty into ecosystem models that are informed solely by experiments and suggest that responses to climate change that are predicted using such models should be re-evaluated.

Wolkovich, E. M.; Cook, B. I.; Allen, J. M.; Crimmins, T. M.; Betancourt, J. L.; Travers, S. E.; Pau, S.; Regetz, J.; Davies, T. J.; Kraft, N. J. B.; Ault, T. R.; Bolmgren, K.; Mazer, S. J.; McCabe, G. J.; McGill, B. J.; Parmesan, C.; Salamin, N.; Schwartz, M. D.; Cleland, E. E.

2012-01-01

64

Greenhouse Effect/Climate Change/Global Warming  

NSDL National Science Digital Library

The terms greenhouse effect, climate change, and global warming are often used interchangeably, yet they really refer to three separate and distinct processes. This activity examines all three and assesses whether Earth's atmosphere is getting warmer. Students will read two articles from the journal of Science that discuss the findings of the Intergovernmental Panel on Climate Change (IPCC) and investigate the bias of both groups of authors. This activity requires the use of two articles from the July 20, 2001 issue of the journal Science.

Fox, Chris

65

Climate extremes and ecosystem productivity in global warming simulations  

NASA Astrophysics Data System (ADS)

Ecosystem responses to present-day droughts and heat-waves are often considered indicative of future global warming impacts on ecosystems, under the assumption that the temperature above which vegetation experiences heat and drought stress is invariant with changes in climate and carbon dioxide concentration. Understanding how the impacts of temperature extremes on ecosystems can change with climate change is essential for correctly evaluating and developing Earth System Models (ESMs). The Coupled Model Inter-comparison Project (CMIP5) historical and future (RCP8.5) climate predictions were analyzed in this study to illustrate non-stationarity of climate impacts on ecosystems, as evident by changes in the distribution of Gross Primary Production (GPP) as a function of temperature between future and historical climates. These changes consist of (1) a uniform shift in the GPP distribution toward warmer temperatures between future and historical climates, and (2) a proportional increase in GPP at all temperatures, consistent with CO2 fertilization. The temperature at which GPP has a local maximum within a given climate increases with global warming and closely tracks the change in mean temperature for each ecosystem. This maximum GPP temperature can be conceptualized as a stable equilibrium determined by the temperature at which an increase in plant water stress is compensated by a decrease in light stress (decreasing cloud cover) with increasing temperature. Temperature relative to the temperature of maximum GPP is proposed as an improved measure of climate extremes more relevant to ecosystem productivity than absolute temperature. The percentage change in GPP attributed to changes in relative temperature extremes is up to 3% per K (decrease in GPP), and reflects both an increase in the frequency of climate extremes in global warming scenarios and the change in temperature criteria for negative climate impacts on ecosystem productivity. Temperature at GPP maximum as a function of the growing season average temperature, for each ecosystem type. Lengths of crosshairs indicate the standard error of the CMIP5 ensemble average. Both future and historical averages are shown (the temperature of GPP maximum increases monotonically with growing season average temperature between future and historical simulations).

Williams, I. N.; Torn, M. S.; Riley, W. J.; Wehner, M. F.; Collins, W.

2013-12-01

66

Reductions in labour capacity from heat stress under climate warming  

NASA Astrophysics Data System (ADS)

A fundamental aspect of greenhouse-gas-induced warming is a global-scale increase in absolute humidity. Under continued warming, this response has been shown to pose increasingly severe limitations on human activity in tropical and mid-latitudes during peak months of heat stress. One heat-stress metric with broad occupational health applications is wet-bulb globe temperature. We combine wet-bulb globe temperatures from global climate historical reanalysis and Earth System Model (ESM2M) projections with industrial and military guidelines for an acclimated individual's occupational capacity to safely perform sustained labour under environmental heat stress (labour capacity)--here defined as a global population-weighted metric temporally fixed at the 2010 distribution. We estimate that environmental heat stress has reduced labour capacity to 90% in peak months over the past few decades. ESM2M projects labour capacity reduction to 80% in peak months by 2050. Under the highest scenario considered (Representative Concentration Pathway 8.5), ESM2M projects labour capacity reduction to less than 40% by 2200 in peak months, with most tropical and mid-latitudes experiencing extreme climatological heat stress. Uncertainties and caveats associated with these projections include climate sensitivity, climate warming patterns, CO2 emissions, future population distributions, and technological and societal change.

Dunne, John P.; Stouffer, Ronald J.; John, Jasmin G.

2013-06-01

67

Bering Sea conditions in the early Pliocene warm period (Invited)  

NASA Astrophysics Data System (ADS)

Detailed studies of the early Pliocene warm period, approx. 3.5 - 4.5 myrs ago, and subsequent expansion of Northern Hemisphere Glaciation, provide insight into the mechanisms that explain amplified high latitude warmth. Although Pliocene surface conditions and meridional overturning circulation have been reconstructed in a few sub-Arctic and Arctic localities, IODP Expedition 323 recovered the first sediments from the Bering Sea appropriate for the study of Pliocene climate change. Early Pliocene sediments were recovered at two sites, U1340 and U1341, at the Bowers Ridge. To augment shipboard data, we generated sedimentological data (i.e., grain size, petrographic, SEM, biogenic opal analyses), and benthic assemblage counts at U1340 and U1341. We also generated diatom assemblage counts, bulk nitrogen isotope analyses, and alkenone saturation (Uk’37) analyses at U1340. Our multi-proxy approach yields the following interpretation of early Pliocene conditions: Relatively high paleoproductivity is interpreted from sedimentological data and diatom assemblage counts which indicate that the sediment is dominated by well-preserved frustules including relatively high abundances of heavily silicified diatom forms. The bulk nitrogen isotope values are relatively low, close to 2 per mil, indicating that there was an abundant supply of surface water nitrate. Sea surface temperatures were about 14 degrees, at least 5 degrees warmer than today. And, benthic foraminifera abundances are dominated by Martinottiella communis suggesting enhanced ventilation of the deep water relative to today. Considering the Bering Sea results in a global context supports the idea that the high latitude oceans were highly productive, that the global meridional temperature gradient was reduced, and that meridional overturning circulation may have been enhanced, relative to today. The warm period ended as early as 3.5 Ma, marked by gradual changes in paleoproductivity and sea surface temperature. Comparison to other paleoclimate records around the globe suggests that high and low latitude cooling were intimately connected through the Pliocene.

Ravelo, A. C.; Takahashi, K.; Aiello, I. W.; Alvarez Zarikian, C. A.; Andreasen, D.; Aung, T. M.; Hioki, Y.; Kanematsu, Y.; Kender, S.; Lariviere, J.; Nagashima, T.; Stroynowski, Z. N.; Scientific Team Of Iodp Expedition 323

2010-12-01

68

Climatic Conditions in Classrooms.  

ERIC Educational Resources Information Center

Presents an overview of research on the ways in which classroom thermal environment, lighting conditions, ion state, and electromagnetic and air pollution affect learning and the performance of students and teachers. (SJL)

Kevan, Simon M.; Howes, John D.

1980-01-01

69

Permafrost carbon-climate feedbacks accelerate global warming.  

PubMed

Permafrost soils contain enormous amounts of organic carbon, which could act as a positive feedback to global climate change due to enhanced respiration rates with warming. We have used a terrestrial ecosystem model that includes permafrost carbon dynamics, inhibition of respiration in frozen soil layers, vertical mixing of soil carbon from surface to permafrost layers, and CH(4) emissions from flooded areas, and which better matches new circumpolar inventories of soil carbon stocks, to explore the potential for carbon-climate feedbacks at high latitudes. Contrary to model results for the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4), when permafrost processes are included, terrestrial ecosystems north of 60°N could shift from being a sink to a source of CO(2) by the end of the 21st century when forced by a Special Report on Emissions Scenarios (SRES) A2 climate change scenario. Between 1860 and 2100, the model response to combined CO(2) fertilization and climate change changes from a sink of 68 Pg to a 27 + -7 Pg sink to 4 + -18 Pg source, depending on the processes and parameter values used. The integrated change in carbon due to climate change shifts from near zero, which is within the range of previous model estimates, to a climate-induced loss of carbon by ecosystems in the range of 25 + -3 to 85 + -16 Pg C, depending on processes included in the model, with a best estimate of a 62 + -7 Pg C loss. Methane emissions from high-latitude regions are calculated to increase from 34 Tg CH(4)/y to 41-70 Tg CH(4)/y, with increases due to CO(2) fertilization, permafrost thaw, and warming-induced increased CH(4) flux densities partially offset by a reduction in wetland extent. PMID:21852573

Koven, Charles D; Ringeval, Bruno; Friedlingstein, Pierre; Ciais, Philippe; Cadule, Patricia; Khvorostyanov, Dmitry; Krinner, Gerhard; Tarnocai, Charles

2011-09-01

70

Estimating present climate in a warming world: a model-based approach  

SciTech Connect

Weather services base their operational definitions of 'present' climate on past observations, using a 30-year normal period such as 1961-1990 or 1971-2000. In a world with ongoing global warming, however, past data give a biased estimate of the actual present-day climate. Here we propose to correct this bias with a 'delta change' method, in which model-simulated climate changes and observed global mean temperature changes are used to extrapolate past observations forward in time, to make them representative of present or future climate conditions. In a hindcast test for the years 1991-2002, the method works well for temperature, with a clear improvement in verification statistics compared to the case in which the hindcast is formed directly from the observations for 1961-1990. However, no improvement is found for precipitation, for which the signal-to-noise ratio between expected anthropogenic changes and interannual variability is much lower than for temperature. An application of the method to the present (around the year 2007) climate suggests that, as a geographical average over land areas excluding Antarctica, 8-9 months per year and 8-9 years per decade can be expected to be warmer than the median for 1971-2000. Along with the overall warming, a substantial increase in the frequency of warm extremes at the expense of cold extremes of monthly-to-annual temperature is expected.

Raeisaenen, J.; Ruokolainen, L. [University of Helsinki (Finland). Division of Atmospheric Sciences and Geophysics

2008-09-30

71

LETTER doi:10.1038/nature09407 Global metabolic impacts of recent climate warming  

E-print Network

LETTER doi:10.1038/nature09407 Global metabolic impacts of recent climate warming Michael E. Dillon and projected climate warming2,13,14 . Global warming is probably having profound and diverse effects phenology3,4 , community interactions5 , genetics3,6 and extinctions7 have been attributed to recent global

Huey, Raymond B.

72

Can ozone depletion and global warming interact to produce rapid climate change?  

E-print Network

Can ozone depletion and global warming interact to produce rapid climate change? Dennis L. Hartmann of Climate Change (IPCC) assess- ment of the status of global warming, which reported that winter stratospheric ozone depletion and greenhouse warming are possible. These interactions may be responsible

Limpasuvan, Varavut

73

Climate changes mirror global warming predictions BY THOMAS CROWLEY Guest columnist  

E-print Network

Climate changes mirror global warming predictions BY THOMAS CROWLEY Guest columnist The Herald" and must reflect, at least in part, the climate system response to the increase in global warming. What if we wanted to prevent global warming. This is just doomsday speaking of the same type that he

74

DO GLOBAL WARMING AND CLIMATE CHANGE REPRESENT A SERIOUS THREAT TO OUR WELFARE  

E-print Network

DO GLOBAL WARMING AND CLIMATE CHANGE REPRESENT A SERIOUS THREAT TO OUR WELFARE AND ENVIRONMENT? By Michael E. Mann I. Introduction The subjects of "global warming" and "climate change" have become parts of both the popular lexicon and the public discourse. Discussions of global warming often evoke passionate

75

Increased Climate Variability Is More Visible Than Global Warming: A General  

E-print Network

Increased Climate Variability Is More Visible Than Global Warming: A General System@utep.edu Abstract While global warming is a statistically confirmed long-term phenomenon, its most visible than the global warming itself. 1 Formulation of the Problem What is global warming. The term "global

Kreinovich, Vladik

76

3, 301336, 2007 Climatic conditions  

E-print Network

of the Past Climatic conditions for modelling the Northern Hemisphere ice sheets throughout the ice age cycle in order to drive an ice sheet model throughout an ice age cycle. Feedback processes between ice sheet sheet feedback is essential for a reliable simulation of ice sheet changes during ice age cycles.15 1

Paris-Sud XI, Université de

77

Trophic level responses differ as climate warms in Ireland.  

PubMed

Effective ecosystem functioning relies on successful species interaction. However, this delicate balance may be disrupted if species do not respond to environmental change at a similar rate. Here we examine trends in the timing of spring phenophases of groups of species occupying three trophic levels as a potential indicator of ecosystem response to climate warming in Ireland. The data sets were of varying length (1976-2009) and from varying locations: (1) timing of leaf unfolding and May Shoot of a range of broadleaf and conifer tree species, (2) first appearance dates of a range of moth species, and (3) first arrival dates of a range of spring migrant birds. All three groups revealed a statistically significant (P<0.01 and P<0.001) advance in spring phenology that was driven by rising spring temperature (P<0.05; 0.45 °C /decade). However, the rate of advance was greater for moths (1.8 days/year), followed by birds (0.37 days/year) and trees (0.29 days/year). In addition, the length of time between (1) moth emergence and leaf unfolding and (2) moth emergence and bird arrival decreased significantly (P<0.05 and P<0.001, respectively), indicating a decrease in the timing between food supply and demand. These differing trophic level response rates demonstrate the potential for a mismatch in the timing of interdependent phenophases as temperatures rise. Even though these data were not specifically collected to examine climate warming impacts, we conclude that such data may be used as an early warning indicator and as a means to monitor the potential for future ecosystem disruption to occur as climate warms. PMID:25380974

Donnelly, Alison; Yu, Rong; Liu, Lingling

2014-11-01

78

Measure Guideline: Supplemental Dehumidification in Warm-Humid Climates  

SciTech Connect

This document covers a description of the need and applied solutions for supplemental dehumidification in warm-humid climates, especially for energy efficient homes where the sensible cooling load has been dramatically reduced. In older homes in warm-humid climates, cooling loads are typically high and cooling equipment runs a lot to cool the air. The cooling process also removes indoor moisture, reducing indoor relative humidity. However, at current residential code levels, and especially for above-code programs, sensible cooling loads have been so dramatically reduced that the cooling system does not run a lot to cool the air, resulting in much less moisture being removed. In these new homes, cooling equipment is off for much longer periods of time especially during spring/fall seasons, summer shoulder months, rainy periods, some summer nights, and some winter days. In warm-humid climates, those long off periods allow indoor humidity to become elevated due to internally generated moisture and ventilation air change. Elevated indoor relative humidity impacts comfort, indoor air quality, and building material durability. Industry is responding with supplemental dehumidification options, but that effort is really in its infancy regarding year-round humidity control in low-energy homes. Available supplemental humidity control options are discussed. Some options are less expensive but may not control indoor humidity as well as more expensive and comprehensive options. The best performing option is one that avoids overcooling and avoids adding unnecessary heat to the space by using waste heat from the cooling system to reheat the cooled and dehumidified air to room-neutral temperature.

Rudd, A.

2014-10-01

79

The effect of slope aspect on the response of snowpack to climate warming in the Pyrenees  

NASA Astrophysics Data System (ADS)

The aim of this study was to analyse the effect of slope aspect on the response of snowpack to climate warming in the Pyrenees. For this purpose, data available from five automatic weather stations were used to simulate the energy and mass balance of snowpack, assuming different magnitudes of an idealized climate warming (upward shifting of 1, 2 and 3 °C the temperature series). Snow energy and mass balance were simulated using the Cold Regions Hydrological Modelling platform (CRHM). CRHM was used to create a model that enabled correction of the all-wave incoming radiation fluxes from the observation sites for various slope aspects (N, NE, E, SE, S, SW,W,NW and flat areas), which enabled assessment of the differential impact of climate warming on snow processes on mountain slopes. The results showed that slope aspect was responsible for substantial variability in snow accumulation and the duration of the snowpack. Simulated variability markedly increased with warmer temperature conditions. Annual maximum snow accumulation (MSA) and annual snowpack duration (ASD) showed marked sensitivity to a warming of 1 °C. Thus, the sensitivity of the MSA in flat areas ranged from 11 to 17 % per degree C amongst the weather stations, and the ASD ranged from 11 to 20 days per degree C. There was a clear increase in the sensitivity of the snowpack to climate warming on those slopes that received intense solar radiation (S, SE and SW slopes) compared with those slopes where the incident radiation was more limited (N, NE and NW slopes). The sensitivity of the MSA and the ASD increased as the temperature increased, particularly on the most irradiated slopes. Large interannual variability was also observed. Thus, with more snow accumulation and longer duration the sensitivity of the snowpack to temperature decreased, especially on south-facing slopes.

López-Moreno, J. I.; Revuelto, J.; Gilaberte, M.; Morán-Tejeda, E.; Pons, M.; Jover, E.; Esteban, P.; García, C.; Pomeroy, J. W.

2014-07-01

80

Climate warming and agricultural stressors interact to determine stream periphyton community composition.  

PubMed

Lack of knowledge about how the various drivers of global climate change will interact with multiple stressors already affecting ecosystems is the basis for great uncertainty in projections of future biological change. Despite concerns about the impacts of changes in land use, eutrophication and climate warming in running waters, the interactive effects of these stressors on stream periphyton are largely unknown. We manipulated nutrients (simulating agricultural runoff), deposited fine sediment (simulating agricultural erosion) (two levels each) and water temperature (eight levels, 0-6 °C above ambient) simultaneously in 128 streamside mesocosms. Our aim was to determine the individual and combined effects of the three stressors on the algal and bacterial constituents of the periphyton. All three stressors had pervasive individual effects, but in combination frequently produced synergisms at the population level and antagonisms at the community level. Depending on sediment and nutrient conditions, the effect of raised temperature frequently produced contrasting response patterns, with stronger or opposing effects when one or both stressors were augmented. Thus, warming tended to interact negatively with nutrients or sediment by weakening or reversing positive temperature effects or strengthening negative ones. Five classes of algal growth morphology were all affected in complex ways by raised temperature, suggesting that these measures may prove unreliable in biomonitoring programs in a warming climate. The evenness and diversity of the most abundant bacterial taxa increased with temperature at ambient but not with enriched nutrient levels, indicating that warming coupled with nutrient limitation may lead to a more evenly distributed bacterial community as temperatures rise. Freshwater management decisions that seek to avoid or mitigate the negative effects of agricultural land use on stream periphyton should be informed by knowledge of the interactive effects of multiple stressors in a warming climate. PMID:24942814

Piggott, Jeremy J; Salis, Romana K; Lear, Gavin; Townsend, Colin R; Matthaei, Christoph D

2015-01-01

81

``Global Warming/Climate Change'': A Critical Look  

NASA Astrophysics Data System (ADS)

There continues to be an increasing number of scientists from around the world who are challenging the dominant claim that has been bolstered by so-called ``consensus'' scientific views -- that dangerous ``global warming/climate change'' is caused primarily by human-produced carbon dioxide. This poster will show scientific evidence contradicting that claim. It will also explain some of the errors that have been introduced from a corruption of the scientific method. (Further information can be found at http://uhaweb.hartford.edu/lgould/)

Gould, Laurence I.

2011-11-01

82

The impact of boreal forest fire on climate warming  

USGS Publications Warehouse

We report measurements and analysis of a boreal forest fire, integrating the effects of greenhouse gases, aerosols, black carbon deposition on snow and sea ice, and postfire changes in surface albedo. The net effect of all agents was to increase radiative forcing during the first year (34 ?? 31 Watts per square meter of burned area), but to decrease radiative forcing when averaged over an 80-year fire cycle (-2.3 ?? 2.2 Watts per square meter) because multidecadal increases in surface albedo had a larger impact than fire-emitted greenhouse gases. This result implies that future increases in boreal fire may not accelerate climate warming.

Randerson, J.T.; Liu, H.; Flanner, M.G.; Chambers, S.D.; Jin, Y.; Hess, P.G.; Pfister, G.; Mack, M.C.; Treseder, K.K.; Welp, L.R.; Chapin, F.S.; Harden, J.W.; Goulden, M.L.; Lyons, E.; Neff, J.C.; Schuur, E.A.G.; Zender, C.S.

2006-01-01

83

The impact of boreal forest fire on climate warming.  

PubMed

We report measurements and analysis of a boreal forest fire, integrating the effects of greenhouse gases, aerosols, black carbon deposition on snow and sea ice, and postfire changes in surface albedo. The net effect of all agents was to increase radiative forcing during the first year (34 +/- 31 Watts per square meter of burned area), but to decrease radiative forcing when averaged over an 80-year fire cycle (-2.3 +/- 2.2 Watts per square meter) because multidecadal increases in surface albedo had a larger impact than fire-emitted greenhouse gases. This result implies that future increases in boreal fire may not accelerate climate warming. PMID:17110574

Randerson, J T; Liu, H; Flanner, M G; Chambers, S D; Jin, Y; Hess, P G; Pfister, G; Mack, M C; Treseder, K K; Welp, L R; Chapin, F S; Harden, J W; Goulden, M L; Lyons, E; Neff, J C; Schuur, E A G; Zender, C S

2006-11-17

84

Impacts of climate warming on alpine glacier tourism and adaptive measures: A case study of Baishui Glacier No. 1 in Yulong Snow Mountain, Southwestern China  

Microsoft Academic Search

Alpine glaciers usually feature with best hydrothermal condition in mountain climate, and present beautiful glacier scenery,\\u000a various glacier landforms, rich biodiversity, and easier accessibility, compared with continental glaciers or ice sheets.\\u000a Nevertheless, Alpine glaciers are more sensitive to climate warming, and climate warming has seriously affected Alpine glaciers\\u000a and surrounding environment. The quality and attractiveness of Alpine glaciers to tourism

Shijin Wang; Yuanqing He; Xiaodong Song

2010-01-01

85

Vertical gradient of climate change and climate tourism conditions in the Black Forest.  

PubMed

Due to the public discussion about global and regional warming, the regional climate and the modified climate conditions are analyzed exemplarily for three different regions in the southern Black Forest (southwest Germany). The driving question behind the present study was how can tourism adapt to modified climate conditions and associated changes to the tourism potential in low mountain ranges. The tourism potential is predominately based on the attractiveness of natural resources being climate-sensitive. In this study, regional climate simulations (A1B) are analyzed by using the REMO model. To analyze the climatic tourism potential, the following thermal, physical and aesthetic parameters are considered for the time span 1961-2050: thermal comfort, heat and cold stress, sunshine, humid-warm conditions (sultriness), fog, precipitation, storm, and ski potential (snow cover). Frequency classes of these parameters expressed as a percentage are processed on a monthly scale. The results are presented in form of the Climate-Tourism-Information-Scheme (CTIS). Due to warmer temperatures, winters might shorten while summers might lengthen. The lowland might be more affected by heat and sultriness (e.g., Freiburg due to the effects of urban climate). To adapt to a changing climate and tourism, the awareness of both stakeholders and tourists as well as the adaptive capability are essential. PMID:19705164

Endler, Christina; Oehler, Karoline; Matzarakis, Andreas

2010-01-01

86

Vertical gradient of climate change and climate tourism conditions in the Black Forest  

NASA Astrophysics Data System (ADS)

Due to the public discussion about global and regional warming, the regional climate and the modified climate conditions are analyzed exemplarily for three different regions in the southern Black Forest (southwest Germany). The driving question behind the present study was how can tourism adapt to modified climate conditions and associated changes to the tourism potential in low mountain ranges. The tourism potential is predominately based on the attractiveness of natural resources being climate-sensitive. In this study, regional climate simulations (A1B) are analyzed by using the REMO model. To analyze the climatic tourism potential, the following thermal, physical and aesthetic parameters are considered for the time span 1961-2050: thermal comfort, heat and cold stress, sunshine, humid-warm conditions (sultriness), fog, precipitation, storm, and ski potential (snow cover). Frequency classes of these parameters expressed as a percentage are processed on a monthly scale. The results are presented in form of the Climate-Tourism-Information-Scheme (CTIS). Due to warmer temperatures, winters might shorten while summers might lengthen. The lowland might be more affected by heat and sultriness (e.g., Freiburg due to the effects of urban climate). To adapt to a changing climate and tourism, the awareness of both stakeholders and tourists as well as the adaptive capability are essential.

Endler, Christina; Oehler, Karoline; Matzarakis, Andreas

2010-01-01

87

Elevated CO2 further lengthens growing season under warming conditions.  

PubMed

Observations of a longer growing season through earlier plant growth in temperate to polar regions have been thought to be a response to climate warming. However, data from experimental warming studies indicate that many species that initiate leaf growth and flowering earlier also reach seed maturation and senesce earlier, shortening their active and reproductive periods. A conceptual model to explain this apparent contradiction, and an analysis of the effect of elevated CO2--which can delay annual life cycle events--on changing season length, have not been tested. Here we show that experimental warming in a temperate grassland led to a longer growing season through earlier leaf emergence by the first species to leaf, often a grass, and constant or delayed senescence by other species that were the last to senesce, supporting the conceptual model. Elevated CO2 further extended growing, but not reproductive, season length in the warmed grassland by conserving water, which enabled most species to remain active longer. Our results suggest that a longer growing season, especially in years or biomes where water is a limiting factor, is not due to warming alone, but also to higher atmospheric CO2 concentrations that extend the active period of plant annual life cycles. PMID:24759322

Reyes-Fox, Melissa; Steltzer, Heidi; Trlica, M J; McMaster, Gregory S; Andales, Allan A; LeCain, Dan R; Morgan, Jack A

2014-06-12

88

Anticipated impacts of climate warming on ecosystems in Interior Alaska  

NASA Astrophysics Data System (ADS)

Future climate scenarios predict a roughly 5 degree increase in mean annual air temperatures for the Alaskan Interior over the next 80 years. This is expected to be enough to initiate permafrost degradation in Interior Alaska which could lead to widespread thermokarst and talik development and potentially a thicker seasonally thawed (active) layer. These changes could dramatically affect hydrology, ground surface topography and vegetation. Forecasting ecological responses to climate warming is complicated by many factors including variations in soil type, precipitation, surface and ground water hydrology, vegetation, slope, aspect, fire prevalence, and the thermal state of permafrost. We are making field measurements and time series repeat imagery at upland and lowland landscapes to determine where and what ecosystem processes may be most susceptible for rapid or unpredictable changes with climate warming or changing land use activities. By integrating existing cryospheric (permafrost and snow), hydrologic and vegetation succession modeling capabilities we hope to enhance our ability to predict how climate change and other stressors may affect ecosystem dynamics and fire susceptibility. We will include the effects of non-climate related anthropogenic stressors like changes in land use activities and infrastructure development. Numerous electrical resistivity geophysical measurements have been made across a variety of landscapes to investigate how vegetation, soils, and land use relates to permafrost distribution. Our project results will be synthesized into a spatially-explicit decision support system to assist with land use management decision-making for Interior Alaska. This Geographic Information Systems (GIS)-based tool is being developed through a combination of field work and modeling. We will identify challenges for management activities given the projected ecosystem response to anticipated climate change by the end-of-the century. This presentation will summarize the first year of research results from this multi-agency, multidisciplinary research project. The project team includes more than 20 researchers, collaborators, students and land users that are actively working on this research program. Results will include geophysical measurements of surface soils and permafrost, the first hydrologic measurements across the Tanana Flats lowlands and the glacier fed Jarvis Creek, repeat imagery of landscapes exhibiting change over time, vegetation mapping, and hydrologic and ecosystem simulations.

Douglas, T. A.; Liljedahl, A. K.; Astley, B. N.; Downer, C. W.; Jorgenson, T. T.; Bagley, C.; Burks-Copes, K.

2011-12-01

89

Terrestrial carbon-cycle feedback to climate warming: experimental evidence on plant regulation and impacts of biofuel feedstock harvest  

Microsoft Academic Search

Feedback between global carbon (C) cycles and climate change is one of the major uncertainties in projecting future global warming. Coupled carbon-climate models all demonstrated a positive feedback between terrestrial C cycle and climate warming. The positive feedback results from decreased net primary production (NPP) in most models and increased respiratory C release by all the models under climate warming.

YIQI LUO; REBECCA SHERRY; XUHUI ZHOU; SHIQIANG WAN

2009-01-01

90

Global Warming, Climate Change and Glacier Retreat of Nepal Himalayas  

NASA Astrophysics Data System (ADS)

Global average air temperature near the earth surface rose 0.74¡¾0.18¨¬C during the twentieth century. The Intergovernmental Panel on Climate Change (IPCC) concludes that observed increased globally averaged temperatures since mid-twentieth century is very likely due to the observed increment in anthropogenic greenhouse gas concentrations, which leads to warming of the surface and lower atmosphere by increasing the greenhouse effect. Climate models referred by IPCC project that global surface temperature are likely to be increase by 1.1 to 6.4¨¬C between 1990 and 2100. An increase in global temperature is expected to cause other changes including glacier retreat, sea level rise, increase intensity of extreme weather events and change in the pattern of precipitation, etc. The Nepal Himalaya revealed 3,252 glaciers and 2,323 lakes, which are 3,500 m above the sea level. They cover an area of 5,323 km2 with an estimated ice reserve of 481 km3. The average temperature in Nepal is rising by 0.5¨¬C per decade, and because of this reason, big glacial lakes in the country are at high risk of flooding from glacial lake bursts, which would have an adverse effect, such as huge loss of life and property. Nepal is facing a disturbance in mountain climate, flash floods, cloudbursts, erratic weather patterns and so on. The death of number of people due to floods and landslides is increasing annually. It is reported that more than 164 people already died because of floods and landslides during the current year, 2007 rainy season. Nepal does emit negligible greenhouse gases compare to developed and industrialized countries, however, country and people are facing the consequences of actions of other developed and industrialized countries. Study shows the¡¡disasters in current years and possible hazards in future due to the probable causes of global warming and recommends some suggestions for controlling of green house gases emission.

Shrestha, S.; Hisaki, Y.

2007-12-01

91

Multisectoral climate impact hotspots in a warming world  

PubMed Central

The impacts of global climate change on different aspects of humanity’s diverse life-support systems are complex and often difficult to predict. To facilitate policy decisions on mitigation and adaptation strategies, it is necessary to understand, quantify, and synthesize these climate-change impacts, taking into account their uncertainties. Crucial to these decisions is an understanding of how impacts in different sectors overlap, as overlapping impacts increase exposure, lead to interactions of impacts, and are likely to raise adaptation pressure. As a first step we develop herein a framework to study coinciding impacts and identify regional exposure hotspots. This framework can then be used as a starting point for regional case studies on vulnerability and multifaceted adaptation strategies. We consider impacts related to water, agriculture, ecosystems, and malaria at different levels of global warming. Multisectoral overlap starts to be seen robustly at a mean global warming of 3 °C above the 1980–2010 mean, with 11% of the world population subject to severe impacts in at least two of the four impact sectors at 4 °C. Despite these general conclusions, we find that uncertainty arising from the impact models is considerable, and larger than that from the climate models. In a low probability-high impact worst-case assessment, almost the whole inhabited world is at risk for multisectoral pressures. Hence, there is a pressing need for an increased research effort to develop a more comprehensive understanding of impacts, as well as for the development of policy measures under existing uncertainty. PMID:24344270

Piontek, Franziska; Müller, Christoph; Pugh, Thomas A. M.; Clark, Douglas B.; Deryng, Delphine; Elliott, Joshua; Colón González, Felipe de Jesus; Flörke, Martina; Folberth, Christian; Franssen, Wietse; Frieler, Katja; Friend, Andrew D.; Gosling, Simon N.; Hemming, Deborah; Khabarov, Nikolay; Kim, Hyungjun; Lomas, Mark R.; Masaki, Yoshimitsu; Mengel, Matthias; Morse, Andrew; Neumann, Kathleen; Nishina, Kazuya; Ostberg, Sebastian; Pavlick, Ryan; Ruane, Alex C.; Schewe, Jacob; Schmid, Erwin; Stacke, Tobias; Tang, Qiuhong; Tessler, Zachary D.; Tompkins, Adrian M.; Warszawski, Lila; Wisser, Dominik; Schellnhuber, Hans Joachim

2014-01-01

92

Climate warming could shift the timing of seed germination in alpine plants  

PubMed Central

Background and Aims Despite the considerable number of studies on the impacts of climate change on alpine plants, there have been few attempts to investigate its effect on regeneration. Recruitment from seeds is a key event in the life-history of plants, affecting their spread and evolution and seasonal changes in climate will inevitably affect recruitment success. Here, an investigation was made of how climate change will affect the timing and the level of germination in eight alpine species of the glacier foreland. Methods Using a novel approach which considered the altitudinal variation of temperature as a surrogate for future climate scenarios, seeds were exposed to 12 different cycles of simulated seasonal temperatures in the laboratory, derived from measurements at the soil surface at the study site. Key Results Under present climatic conditions, germination occurred in spring, in all but one species, after seeds had experienced autumn and winter seasons. However, autumn warming resulted in a significant increase in germination in all but two species. In contrast, seed germination was less sensitive to changes in spring and/or winter temperatures, which affected only three species. Conclusions Climate warming will lead to a shift from spring to autumn emergence but the extent of this change across species will be driven by seed dormancy status. Ungerminated seeds at the end of autumn will be exposed to shorter winter seasons and lower spring temperatures in a future, warmer climate, but these changes will only have a minor impact on germination. The extent to which climate change will be detrimental to regeneration from seed is less likely to be due to a significant negative effect on germination per se, but rather to seedling emergence in seasons that the species are not adapted to experience. Emergence in autumn could have major implications for species currently adapted to emerge in spring. PMID:22596094

Mondoni, Andrea; Rossi, Graziano; Orsenigo, Simone; Probert, Robin J.

2012-01-01

93

Why are climate models reproducing the observed global surface warming so well?  

E-print Network

Why are climate models reproducing the observed global surface warming so well? Reto Knutti1 global surface warming so well?, Geophys. Res. Lett., 35, L18704, doi:10.1029/ 2008GL034932. 1 models reproduce the observed surface warming better than one would expect given the uncertainties

Fischlin, Andreas

94

Global warming and changes in risk of concurrent climate extremes: Insights from the 2014 California drought  

NASA Astrophysics Data System (ADS)

warming and the associated rise in extreme temperatures substantially increase the chance of concurrent droughts and heat waves. The 2014 California drought is an archetype of an event characterized by not only low precipitation but also extreme high temperatures. From the raging wildfires, to record low storage levels and snowpack conditions, the impacts of this event can be felt throughout California. Wintertime water shortages worry decision-makers the most because it is the season to build up water supplies for the rest of the year. Here we show that the traditional univariate risk assessment methods based on precipitation condition may substantially underestimate the risk of extreme events such as the 2014 California drought because of ignoring the effects of temperature. We argue that a multivariate viewpoint is necessary for assessing risk of extreme events, especially in a warming climate. This study discusses a methodology for assessing the risk of concurrent extremes such as droughts and extreme temperatures.

AghaKouchak, Amir; Cheng, Linyin; Mazdiyasni, Omid; Farahmand, Alireza

2014-12-01

95

A brief history of climate the northern seas from the Last Glacial Maximum to global warming  

E-print Network

with reconstructed ocean temperatures. It is found that maritime climate and the strength of the Norwegian Atlantic climate. This interaction between a variable ocean circulation and climate is therefore central to current1 A brief history of climate ­ the northern seas from the Last Glacial Maximum to global warming

Drange, Helge

96

A Vast Machine Computer Models, Climate Data, and the Politics of Global Warming  

E-print Network

A Vast Machine Computer Models, Climate Data, and the Politics of Global Warming Paul N. Edwards models, climate data, and the politics of global warming / Paul N. Edwards. p. cm. Includes. Climatology--History. 3. Meteorology--History. 4. Climatology--Technological innovation. 5. Global temperature

97

THE CLIMATE AT UW-MADISON: BEGINS SUNNY AND WARM, ENDS CHILLY  

E-print Network

THE CLIMATE AT UW-MADISON: BEGINS SUNNY AND WARM, ENDS CHILLY Submitted to: Molly Carnes, Jo--Do not cite or circulate #12;The Climate at UW-Madison: Begins Sunny and Warm, Ends Chilly Executive Summary initiatives and programs. The following report documents the second issue study funded by this grant

Sheridan, Jennifer

98

Permafrost, Lakes, and Climate-Warming Methane Feedback: What is the Worst  

E-print Network

on the prevalence of lakes, its subsequent methane emission, and potential feedback under climate warming. We findPermafrost, Lakes, and Climate-Warming Methane Feedback: What is the Worst We Can Expect? Xiang Gao No. 218 May 2012 #12;The MIT Joint Program on the Science and Policy of Global Change

99

Plant movements and climate warming: intraspecific variation in growth responses to nonlocal soils.  

PubMed

Most range shift predictions focus on the dispersal phase of the colonization process. Because moving populations experience increasingly dissimilar nonclimatic environmental conditions as they track climate warming, it is also critical to test how individuals originating from contrasting thermal environments can establish in nonlocal sites. We assess the intraspecific variation in growth responses to nonlocal soils by planting a widespread grass of deciduous forests (Milium effusum) into an experimental common garden using combinations of seeds and soil sampled in 22 sites across its distributional range, and reflecting movement scenarios of up to 1600 km. Furthermore, to determine temperature and forest-structural effects, the plants and soils were experimentally warmed and shaded. We found significantly positive effects of the difference between the temperature of the sites of seed and soil collection on growth and seedling emergence rates. Migrant plants might thus encounter increasingly favourable soil conditions while tracking the isotherms towards currently 'colder' soils. These effects persisted under experimental warming. Rising temperatures and light availability generally enhanced plant performance. Our results suggest that abiotic and biotic soil characteristics can shape climate change-driven plant movements by affecting growth of nonlocal migrants, a mechanism which should be integrated into predictions of future range shifts. PMID:24387238

De Frenne, Pieter; Coomes, David A; De Schrijver, An; Staelens, Jeroen; Alexander, Jake M; Bernhardt-Römermann, Markus; Brunet, Jörg; Chabrerie, Olivier; Chiarucci, Alessandro; den Ouden, Jan; Eckstein, R Lutz; Graae, Bente J; Gruwez, Robert; Hédl, Radim; Hermy, Martin; Kolb, Annette; Mårell, Anders; Mullender, Samantha M; Olsen, Siri L; Orczewska, Anna; Peterken, George; Pet?ík, Petr; Plue, Jan; Simonson, William D; Tomescu, Cezar V; Vangansbeke, Pieter; Verstraeten, Gorik; Vesterdal, Lars; Wulf, Monika; Verheyen, Kris

2014-04-01

100

Thermodynamical constraints on the meridional overturning circulation in warming climates  

NASA Astrophysics Data System (ADS)

In midlatitudes of present-day climate, the circulation averaged on moist isentropes is twice as strong as the circulation averaged on dry isentropes (Pauluis et al., 2010, J. Clim.). In the A1B climate scenario, Laliberte and Pauluis (2010, GRL) showed that the winter moist circulation strengthens with respect to the dry circulation, indicating that the latent heat component of the circulation increases at the expense of the sensible heat component. Climate modeling studies covering a wide range of surface temperatures support this observation and show that the overturning circulation attains a maximum and then weakens as surface temperatures rise (Caballero and Langen, 2005, GRL; Rose and Ferreira, 2012, J. Clim). The latent heat component of the circulation therefore cannot increase indefinitely with rising surface temperatures, indicating that a thermodynamical constraint might determine the maximum relative strength of the moist and dry circulations circulation attainable in warmer climates. Here, such a constraint is derived using a theoretical model describing the structure of the dry and moist isentropic circulations in the lower troposphere. The model decomposes the meridional flow in the troposphere into three contributions: a dry equatorward flow; a cold/moist equatorward flow; and a warm/moist poleward flow in the mixed layer. It is based on the joint distribution of meridional mass fluxes in potential temperature and equivalent potential temperature. It updates an existing model of the dry circulation by emphasizing the role of moisture in the mixed layer. The model is used to derive an expression for the ratio of moist to dry circulations strengths, which is used to assess the influence of surface thermodynamics on the circulations. This expression indicates that while an increase in the total heat fluxes occurs when surface temperature variability increases (via an increase in latent heat flux), it cannot increase indefinitely.

Laliberté, F. B.; Shaw, T. A.; Pauluis, O. M.; Kushner, P. J.

2012-12-01

101

Climate Change over the Equatorial Indo-Pacific in Global Warming* CHIE IHARA, YOCHANAN KUSHNIR, AND MARK A. CANE  

E-print Network

Climate Change over the Equatorial Indo-Pacific in Global Warming* CHIE IHARA, YOCHANAN KUSHNIR to global warming is investigated using model outputs submitted to the Intergovernmental Panel on Climate equatorial Indian Ocean warm more than the SSTs in the eastern equatorial Indian Ocean under global warming

102

Climate warming and estuarine and marine coastal ecosystems  

SciTech Connect

Estuaries are physically controlled, resilient coastal ecosystems harboring environmentally tolerant species in diluted seawater. Marine coastal systems are less stressed physically and contain some environmentally less tolerant species. Both systems are biologically productive and economically significant. Because of their complex structure and function, it is difficult to predict accurately the effects of climate change, but some broad generalizations can be made. If climate warming occurs, it will raise sea-level, heat shallow waters, and modify precipitation, wind, and water circulation patterns. Rapid sea-level rise could cause the loss of salt marshes, mangrove swamps, and coral reefs, thus diminishing the ecological roles of these highly productive systems. Warmer waters could eliminate heat-sensitive species from part of their geographical range while allowing heat-tolerant species to expand their range, depending on their ability to disperse. Most thermally influenced losses of species will probably only be local, but changed distributions may lead to changed community function. It is more difficult to predict the effects of modified precipitation, wind, and water circulation patterns, but changes could affect organisms dependent on such patterns for food production (e.g., in upwelling regions) or for retention in estuaries. Aquacultural and fishery-related enterprises would be affected negatively in some regions and positively in others. 73 refs.

Kennedy, V.S. [Univ. of Maryland Center for Environmental and Estuarine Studies, Cambridge, MD (United States). Horn Point Environmental Lab.

1994-12-31

103

Anticyclonic atmospheric circulation as an analogue for the warm and dry mid-Holocene summer climate in central Scandinavia  

NASA Astrophysics Data System (ADS)

Climate reconstructions from central Scandinavia suggest that annual and summer temperatures were rising during the early Holocene and reached their maximum after 8000 cal yr BP. The period with highest temperatures was characterized by increasingly low lake-levels and dry climate, with driest and warmest conditions at about 7000 to 5000 cal yr BP. We compare the reconstructed climate pattern with simulations of a climate model for the last 9000 yr and show that the model, which is predominantly driven by solar insolation patterns, fails to produce the reconstructed mid-Holocene dry and warm period in Scandinavia. As an alternative explanation for the reconstructed climate, we hypothesize that the trend from the moist early Holocene towards dry and warm mid-Holocene was caused by a changing atmospheric circulation pattern with a mid-Holocene dominance of summer-time anticyclonic circulation. An extreme case of the anticyclonic conditions is the persistent blocking high, an atmospheric pressure pattern that at present often causes long spells of particularly dry and warm summer weather, or "Indian summers". The hypothesis is tested with daily instrumental temperature and precipitation records in central Sweden and an objective circulation classification based on surface air pressure over the period 1900-2002. It is concluded that the differences between the precipitation and temperature climates under anticyclonic and non-anticyclonic conditions are significant. Further, warm and dry combination, as indicated by mid-Holocene reconstructions, is a typical pattern under anticyclonic conditions. These results indicate that the presented hypothesis for the mid-Holocene climate is likely valid.

Antonsson, K.; Chen, D.; Seppä, H.

2008-05-01

104

Anticyclonic atmospheric circulation as an analogue for the warm and dry mid-Holocene summer climate in central Scandinavia  

NASA Astrophysics Data System (ADS)

Climate reconstructions from central Scandinavia suggest that annual and summer temperatures were rising during the early Holocene and reached their maximum after 8000 cal yr BP. The period with highest temperatures was characterized by increasingly low lake-levels and dry climate, with driest and warmest conditions at about 7000 to 5000 cal yr BP. We compare the reconstructed climate pattern with simulations of a climate model for the last 9000 years and show that the model, which is predominantly driven by solar insolation patterns, suggests less prominent mid-Holocene dry and warm period in Scandinavia than the reconstructions. As an additional explanation for the reconstructed climate, we argue that the trend from the moist early Holocene towards dry and warm mid-Holocene was caused by a changing atmospheric circulation pattern with a mid-Holocene dominance of summer-time anticyclonic circulation. An extreme case of the anticyclonic conditions is the persistent blocking high, an atmospheric pressure pattern that at present often causes long spells of particularly dry and warm summer weather, or "Indian summers". The argument is tested with daily instrumental temperature and precipitation records in central Sweden and an objective circulation classification based on surface air pressure over the period 1900 2002. We conclude that the differences between the precipitation and temperature climates under anticyclonic and non-anticyclonic conditions are significant. Further, warm and dry combination, as indicated by mid-Holocene reconstructions, is a typical pattern under anticyclonic conditions. These results indicate that the presented hypothesis for the mid-Holocene climate is likely valid.

Antonsson, K.; Chen, D.; Seppä, H.

2008-10-01

105

Climate warming and permafrost dynamics in the Antarctic Peninsula region  

NASA Astrophysics Data System (ADS)

Dramatic warming of the climate over the last several decades has influenced the properties and distribution of permafrost in the Antarctic Peninsula region. Five approaches were used to estimate the distribution of permafrost in the region: (1) correlation of permafrost distribution with mean annual air temperature isotherms, (2) mapping the distribution of periglacial features indicative of permafrost, (3) summarizing data from shallow excavations and boreholes, (4) detection of permafrost from geophysical techniques, and (5) application of models to predict the occurrence of permafrost. Whereas permafrost is continuous in the South Orkney Islands (60-61° S) and along the eastern Antarctic Peninsula (63-65° S), it is discontinuous in the South Shetland Islands (62-63° S), and occurs only sporadically in the Palmer Archipelago and Biscoe Islands along the western Antarctic Peninsula (64-66° S). Permafrost then becomes continuous on Alexander Island (71-74° S) along the western Antarctic Peninsula as the maritime climate shifts to a more continental climate. Reports prior to 1980 mention the presence of permafrost at depths of 25 to 35 cm in ice-free areas near Palmer Station (64°46? S; 64°04? W), where the mean annual air temperature from extrapolation of data from the nearby Vernadsky Station has increased 3.4 °C and the mean winter temperature has increased 6 °C since 1950. Recent measurements suggest that permafrost is absent or close to 0 °C in the upper 14 m of the highest ice-free areas (67 m a.s.l.) near Palmer Station. Permafrost temperatures elsewhere along the western Antarctic Peninsula region range from - 0.4 to - 1.8 °C in the South Shetland Islands (62-63° S) to - 3.1 °C at Adelaide Island (67°34? S). Permafrost at this temperature is susceptible to thawing, which has resulted in historic increases in active-layer thicknesses and in thermokarst features such as debris flows, and active-layer detachment slides.

Bockheim, J.; Vieira, G.; Ramos, M.; López-Martínez, J.; Serrano, E.; Guglielmin, M.; Wilhelm, K.; Nieuwendam, A.

2013-01-01

106

Activity restriction and the mechanistic basis for extinctions under climate warming.  

PubMed

Correlative analyses predict that anthropogenic climate warming will cause widespread extinction but the nature and generality of the underlying mechanisms is unclear. Warming-induced activity restriction has been proposed as a general explanatory mechanism for recent population extinctions in lizards, and has been used to forecast future extinction. Here, I test this hypothesis using globally applied biophysical calculations of the effects of warming and shade reduction on potential activity time and whole-life-cycle energy budgets. These 'thermodynamic niche' analyses show that activity restriction from climate warming is unlikely to provide a general explanation of recent extinctions, and that loss of shade is viable alternative explanation. Climate warming could cause population declines, even under increased activity potential, through joint impacts on fecundity and mortality rates. However, such responses depend strongly on behaviour, habitat (shade, food) and life history, all of which should be explicitly incorporated in mechanistic forecasts of extinction risk under climate change. PMID:24118740

R Kearney, Michael

2013-12-01

107

Disparity in elevational shifts of European trees in response to recent climate warming.  

PubMed

Predicting climate-driven changes in plant distribution is crucial for biodiversity conservation and management under recent climate change. Climate warming is expected to induce movement of species upslope and towards higher latitudes. However, the mechanisms and physiological processes behind the altitudinal and latitudinal distribution range of a tree species are complex and depend on each tree species features and vary over ontogenetic stages. We investigated the altitudinal distribution differences between juvenile and adult individuals of seven major European tree species along elevational transects covering a wide latitudinal range from southern Spain (37°N) to northern Sweden (67°N). By comparing juvenile and adult distributions (shifts on the optimum position and the range limits) we assessed the response of species to present climate conditions in relation to previous conditions that prevailed when adults were established. Mean temperature increased by 0.86 °C on average at our sites during the last decade compared with previous 30-year period. Only one of the species studied, Abies alba, matched the expected predictions under the observed warming, with a maximum abundance of juveniles at higher altitudes than adults. Three species, Fagus sylvatica, Picea abies and Pinus sylvestris, showed an opposite pattern while for other three species, such as Quercus ilex, Acer pseudoplatanus and Q. petraea, we were no able to detect changes in distribution. These findings are in contrast with theoretical predictions and show that tree responses to climate change are complex and are obscured not only by other environmental factors but also by internal processes related to ontogeny and demography. PMID:23572443

Rabasa, Sonia G; Granda, Elena; Benavides, Raquel; Kunstler, Georges; Espelta, Josep M; Ogaya, Romá; Peñuelas, Josep; Scherer-Lorenzen, Michael; Gil, Wojciech; Grodzki, Wojciech; Ambrozy, Slawomir; Bergh, Johan; Hódar, José A; Zamora, Regino; Valladares, Fernando

2013-08-01

108

The impact of exceptionally warm summer inflow events on the environmental conditions in the Bornholm Basin  

NASA Astrophysics Data System (ADS)

In late summer 2002 and 2003, exceptionally warm inflow events of saline water were observed in the Baltic. These warm saline waters were embedded in the halocline of the Bornholm Basin and caused a strong anomaly of the seasonal temperature cycle. The temperature in October 2002 was the highest ever observed in the halocline of the Bornholm Basin. Although the oxygen content of the inflowing water was only about 1.5 ml l - 1 at the Darss Sill, it caused a moderate ventilation of the halocline in the Bornholm Basin. On the way through the Arkona Basin, the entrainment of ambient water increased the oxygen content of the inflowing saline water masses. Warm summer inflows were rare events in the last 50 years, but their frequency has increased since 1990. This is likely caused by climate change. The analysis of a 50-year time series of hydrographic parameters reveals significant changes of the thermal regime around the year 1988. The winter surface and intermediate water temperatures of the Bornholm Basin increased by about 1 °C. Also, the duration of warm water in the surface layer was prolonged after 1988. A high correlation between the minimum intermediate winter water temperatures and the NAO winter index was found. Since temperature is a key parameter for many biological processes various responses of the ecosystem to the change in hydrographic conditions could be expected. Possible biological implications of the warm inflow events for the ecosystem are discussed.

Mohrholz, Volker; Dutz, Jörg; Kraus, Gerd

2006-05-01

109

Adaptability and adaptations of California's water supply system to dry climate warming  

E-print Network

Adaptability and adaptations of California's water supply system to dry climate warming Josué adaptive water management for this climate scenario is compared to a similar scenario with the historical and management problems including climate change impact and adaptation studies (Draper et al. 2003; Harou

Pasternack, Gregory B.

110

Enhanced Climatic Warming Over the Tibetan Plateau Due to Doubling CO2: A Model Study  

NASA Technical Reports Server (NTRS)

A number of studies have presented the evidences that surface climate change associated with global warming at high elevation sites shows more pronounced warming than at low elevations, i.e. an elevation dependency of climatic warming pointed out that snow-albedo feedback may be responsible for the excessive warming in the Swiss Alps. From an ensemble of climate change experiments of increasing greenhouse gases and aerosols using an air-sea coupled climate model, Eyre and Raw (1999) found a marked elevation dependency of the simulated surface screen temperature increase over the Rocky Mountains. Using almost all available instrumental records, Liu and Chen (2000) showed that the main portion of the Tibetan Plateau (TP) has experienced significant ground temperature warming since the middlebrows, especially in winter, and that there is a tendency for the warming trend to increase with elevation in the TP as well as its surrounding areas. In this paper, we will investigate the mechanism of elevation dependency of climatic warming in the TP by using a high-resolution regional climate model.

Chen, Baode; Chao, Winston C.; Liu, Xiaodong; Lau, William K. M. (Technical Monitor)

2001-01-01

111

Warm Eocene climate enhanced petroleum generation from Cretaceous source rocks: A potential climate feedback mechanism?  

NASA Astrophysics Data System (ADS)

Earth surface temperatures, including in the deep sea increased by 5-10°C from the late Paleocene ca. 58 Myr ago to the Early Eocene Climatic Optimum (EECO) centered at about 51 Myr ago. A large (˜2.5‰) drop in ?13C of carbonate spans much of this interval. This suggests a long-term increase in the net flux of 13C-depleted carbon to the ocean and atmosphere that is difficult to explain by changes in surficial carbon cycling alone. We reveal a relationship between surface temperature increase and increased petroleum generation in sedimentary basins operating on 100 kyr to Myr time scales. We propose that early Eocene warming has led to a synchronization of periods of maximum petroleum generation and enhanced generation in otherwise unproductive basins through extension of the volume of source rock within the oil and gas window across hundreds of sedimentary basins globally. Modelling the thermal evolution of four sedimentary basins in the southwest Pacific predicted an up to 50% increase in petroleum generation that would have significantly increased leakage of light hydrocarbons and oil degeneration products into the atmosphere. Extrapolating our modelling results to hundreds of sedimentary basins worldwide suggests that globally increased leakage could have caused a climate feedback effect, driving or enhancing early Eocene climate warming.

Kroeger, K. F.; Funnell, R. H.

2012-02-01

112

Precipitation Rates in a Stable Warm and Wet Climate on Early Mars  

NASA Astrophysics Data System (ADS)

The Noachian river valley networks on Mars are thought to have formed under warm and wet conditions. Two conditions need to be met. The surface temperatures must have been warm enough to allow liquid water at the surface, and enough precipitation must have fallen to the surface on a yearly basis to maintain at least a seasonal flow of water, or flash floods over a long period of time. Using a general circulation model, we find that a warm climate could have been sustained by the greenhouse effect created by the hydrological cycle on early Mars with a 500 mb CO2 atmosphere, and a reduced solar constant. The required conditions for such a climate are: an initial injection of atmospheric water or a low-albedo ice cap, relatively high clouds with particle sizes near 10 ?m that do not precipitate efficiently, and horizontally extensive clouds that trap outgoing infrared radiation. We also find that to have significant precipitation at latitudes where the river valleys are found requires local sources of water at the surface. In the case of a large initial injection of atmospheric water, such local sources of water can form as snow deposits when the planet is in high obliquity (?45°). Oceans can also act as a local source of water. We present simulation results with oceans that reach to -2550 m (Arabia shoreline in the northern hemisphere, Hellas basin, and Argyre basin in the southern hemisphere). Such oceans freeze quickly and form ice layers that are meters thick. However the amount of water sublimated from the ice is sufficient to create significant precipitation in non-polar latitudes at all obliquities. With oceans, the obliquity determines the latitude for highest precipitation. Then the obliquity cycle explains why the river valleys are found across such a wide range of latitudes.

Urata, Richard; Toon, O. B.

2012-10-01

113

Assessing orbitally-forced interglacial climate variability during the mid-Pliocene Warm Period  

NASA Astrophysics Data System (ADS)

The traditional view of the Pliocene is one of an epoch with higher than present global mean annual temperatures (?2 to 3 °C) and stable climate conditions. Published data-model comparisons for the mid-Pliocene Warm Period (mPWP: ?3.3 to 3 million years ago) have identified specific regions of concordance and discord between climate model outputs and marine/terrestrial proxy data. Due to the time averaged nature of global palaeoenvironmental syntheses, it has been hypothesised that climate variability during interglacial events within the mPWP could contribute to site-specific data/model disagreement. The Hadley Centre Coupled Climate Model Version 3 (HadCM3) is used to assess the nature of climate variability around two interglacial events within the mPWP that have different characteristics of orbital forcing (Marine Isotope Stages KM5c and K1). Model results indicate that ±20 kyr on either side of the MIS KM5c, orbital forcing produced a less than 1 °C change in global mean annual temperatures. Regionally, mean annual surface air temperature (SAT) variability can reach 2 to 3 °C. Seasonal variations exceed those predicted for the annual mean and can locally exceed 5 °C. Simulations 20 kyr on either side of MIS K1 show considerably increased variability in relation to KM5c. We demonstrate that orbitally-forced changes in surface air temperature during interglacial events within the mPWP can be substantial, and could therefore contribute to data/model discord. This is especially likely if proxies preserve growing season rather than mean annual temperatures. Model results indicate that peak MIS KM5c and K1 interglacial temperatures were not globally synchronous, highlighting leads and lags in temperature in different regions. This highlights the potential pitfalls in aligning peaks in proxy-derived temperatures across geographically diverse data sites, and indicates that a single climate model simulation for an interglacial event is inadequate to capture peak temperature change in all regions. We conclude that the premise of sustained global warmth and stable Pliocene climate conditions is incomplete. We also contend that the likely nature of Pliocene interglacial climate variability is more akin to interglacial events within the Quaternary, where the character of interglacials is known to be diverse. In the future, the utility of Pliocene data/model comparisons is dependent upon 1) establishing precise chronology of the proxy data, 2) providing climate models with fully proxy-consistent boundary conditions and 3) in utilising ensembles of climate simulations that can adequately capture orbital variability around any studied interval.

Prescott, Caroline L.; Haywood, Alan M.; Dolan, Aisling M.; Hunter, Stephen J.; Pope, James O.; Pickering, Steven J.

2014-08-01

114

Effects Of Climate, Permafrost And Fire On Potential Vegetation Change In Siberia In A Warming Climate  

NASA Astrophysics Data System (ADS)

Observations and general circulation model projections suggest significant temperature increases in Siberia this century, which are expected to have profound effects on Siberian vegetation. Increased permafrost melt and forest fire directly affected by climate warming are predicted to additionally influence vegetation change. Our goal is to model potential vegetation change across Siberia (within the territory between the Urals and Yakutia and between the southern border of Russia and the Arctic ocean) using several Hadley Center climate change scenarios for 2020, 2050 and 2080, with explicit consideration of permafrost and fire activity. To predict vegetation change, we use SiBCliM, our Siberian BioClimatic Model, an envelope-type model that predicts a vegetation type from three climatic indices: growing degree days, base 5oC; negative degree days below 0oC; and annual moisture index (a ratio between growing degree days and annual precipitation). All vegetation predictions are corrected for the influence of climate on permafrost active layer depth. Potential fire danger is evaluated using a regression model that relates the annual number of high fire danger days (Nesterov index is 4000-10000) to annual moisture index. Shifts in the climate necessary to support current Siberian vegetation are notable by 2020. Biomes and major tree species are predicted to shift northwards as far as 600-1000 km by 2080. Forest-steppe and steppe ecosystems rather than forests are predicted to dominate over half of Siberia due to the dryer climate. Despite the large predicted increases in warming, permafrost is not predicted to thaw deep enough to sustain dark taiga. Over eastern Siberia, larch (Larix dahurica) taiga is predicted to continue to be the dominant zonobiome because of their ability to withstand continuous permafrost. Our model also predicts new temperate broadleaf and forest-steppe habitats by 2080. Fire danger is predicted to increase by 2080, especially in southern Siberia, where wildland fires would promote habitats for steppe and forest-steppe. Melting permafrost and fire are the principal mechanisms that facilitate vegetation change, which leads to a new equilibrium between vegetation and climate across Siberia.

Tchebakova, N. M.; Parfenova, E. I.; Soja, A. J.

2008-12-01

115

The tundra warms and grows The effects of climate change on tundra  

E-print Network

ECOLOGY The tundra warms and grows The effects of climate change on tundra in the high Arctic on the tundra of Ellesmere Island in Nunavut, Canada, show an ecosystem `in transition'. Temperatures have risen

116

Climate-induced changes in carbon and nitrogen cycling in the rapidly warming Antarctic coastal ocean   

E-print Network

The western Antarctic Peninsula (WAP) is a hotspot of climatic and oceanographic change, with a 6°C rise in winter atmospheric temperatures and >1°C warming of the surface ocean since the 1950s. These trends are having ...

Henley, Sian Frances

2013-07-01

117

Impacts of climate change in a global hotspot for temperate marine biodiversity and ocean warming  

Microsoft Academic Search

Temperate Australia is a global hotspot for marine biodiversity and its waters have experienced well-above global average rates of ocean warming. We review the observed impacts of climate change (e.g. warming, ocean acidification, changes in storm patterns) on subtidal temperate coasts in Australia and assess how these systems are likely to respond to further change. Observed impacts are region specific

Thomas Wernberg; Bayden D. Russell; Pippa J. Moore; Scott D. Ling; Daniel A. Smale; Alex Campbell; Melinda A. Coleman; Peter D. Steinberg; Gary A. Kendrick; Sean D. Connell

2011-01-01

118

Rapid micro-evolution and loss of chromosomal diversity in Drosophila in response to climate warming  

E-print Network

impact of rapid global warming has encouraged research on climate-induced changes in biological systems warming FRANCISCO RODRI� GUEZ-TRELLES* and MIGUEL A. RODRI� GUEZà Department of Ecology and Evolutionary. Critical problems, still poorly understood, are the potential for rapid adaptive responses

Rodríguez, Miguel Ángel

119

A latitudinal gradient in tree growth response to climate warming in the Siberian taiga  

E-print Network

A latitudinal gradient in tree growth response to climate warming in the Siberian taiga A N D R E Siberian taiga species, Larix cajanderi, Picea obovata, and Pinus sylvestris, across a latitudinal gradient that increased productivity with warming is likely only in the northern reaches of the Siberian taiga

Wagner, Diane

120

Climate warming affects biological invasions by shifting interactions of plants and herbivores  

E-print Network

directly but also indirectly through changes in their natural enemies. To date, however, there are no tests of how climate warming shifts the interactions among invasive plants and their natural enemies to affect temperature. Together, these results suggest that warming will allow the natural enemy to expand its range

Siemann, Evan

121

LandOcean Warming Contrast over a Wide Range of Climates: Convective Quasi-Equilibrium Theory  

E-print Network

previously been proposed that this land­ocean warming contrast is related to different changes in lapse ratesLand­Ocean Warming Contrast over a Wide Range of Climates: Convective Quasi-Equilibrium Theory management and policy proposals; understand complex connections among the many forces that will shape our

122

Simulated increase of hurricane intensities in a COâ-warmed climate  

Microsoft Academic Search

Hurricanes can inflict catastrophic property damage and loss of human life. Thus, it is important to determine how the character of these powerful storms could change in response to greenhouse gas-induced global warming. The impact of climate warming on hurricane intensities was investigated with a regional, high-resolution, hurricane prediction model. In a case study, 51 western Pacific storm cases under

T. R. Knutson; R. E. Tuleya; Y. Kurihara

1998-01-01

123

Subtropical climate change during the Pliocene warm period- The strong role of eccentricity and precessional forcing modulation during equable climates  

NASA Astrophysics Data System (ADS)

The Pliocene Epoch (5.3-1.8 Ma) is the most recent geologic period of sustained global warmth. Understanding how the world responded to these warmer conditions has important implications as an analog for future anthropogenic warming of the Earth. Past climate reconstructions of the Pliocene warm period (pWP, 4-3 Ma) suggest that mean annual temperatures were approximately 3°C warmer than present, although reconstructions from the Southern Hemisphere (SH) are sparse. The Southern Ocean plays a key role in regulating global climate, so high-resolution reconstructions from this region are important for understanding global climate processes. These processes include climate-ice-sea level interactions, as significant continental ice was only found in the Southern Hemisphere during the pWP. Very little is understood about SH ocean dynamics and climate variability under the unipolar climate conditions of the pWP. Of particular interest are the links between sea surface temperatures (SSTs) and orbital forcing of the unipolar ice sheet dynamics and changes in intermediate water mass properties via ?18O affecting the heat transport under warmer climate. We will present high-resolution (~2.5 kyr sample resolution) records of climate change in the surface and intermediate waters (1365 m. water depth) of the Southwest Pacific (ODP site 1125) during the pWP. Average alkenone-derived SSTs for the pWP at site ODP 1125 are warmer (18.6 °C) than Holocene SSTs in the region (16.3 °C, using multiple proxies for the last 10 kyr) as well as warmer than modern oceanographic data (14.6 °C). The glacial to interglacial temperatures observed in the pWP at ODP 1125 have a smaller range (21.0-15.5 °C) compared to glacial-interglacial temperatures observed in the late Pleistocene (18.0-11.5 °C) in the region, highlighting the reduced orbital-scale variability of subtropical surface waters during the pWP. Available datasets of pWP SSTs show that the reduced orbital-scale variability of surface waters is greater in the tropical regions by almost two-fold compared to higher latitudes. This high contrast of tropical versus higher latitude variability may indicate a more active role of the higher latitudes in re-distributing heat at the glacial-interglacial scales or that feedbacks at high latitudes are stronger relative to tropics in pWP relative to late Pleistocene. Our findings provide evidence for eccentricity and precessional forcing modulating the ?18O of benthic foraminifera at ODP 1125 and to a lesser degree the SSTs, while the obliquity response is not as prevalent on either surface or intermediate water signals. Relative contributions of eccentricity-precession and obliquity are higher at ODP 1125 compared to global benthic isotope stacks, underscoring the need for more high-resolution records, in the hemisphere with most ice, to detangle the controls (temperature vs. ice volume) in the benthic isotope record. Our findings of high eccentricity and precessional response in the ?18O of intermediate waters provide support for a strong control of the seasonal contrast in intermediate water formation during past warm climates.

Caballero Gill, R. P.; Herbert, T.

2012-12-01

124

Climate change affects low trophic level marine consumers: warming decreases copepod size and abundance.  

PubMed

Concern about climate change has re-ignited interest in universal ecological responses to temperature variations: (1) biogeographical shifts, (2) phenology changes, and (3) size shifts. In this study we used copepods as model organisms to study size responses to temperature because of their central role in the pelagic food web and because of the ontogenetic length constancy between molts, which facilitates the definition of size of distinct developmental stages. In order to test the expected temperature-induced shifts towards smaller body size and lower abundances under warming conditions, a mesocosm experiment using plankton from the Baltic Sea at three temperature levels (ambient, ambient +4 °C, ambient -4 °C) was performed in summer 2010. Overall copepod and copepodit abundances, copepod size at all life stages, and adult copepod size in particular, showed significant temperature effects. As expected, zooplankton peak abundance was lower in warm than in ambient treatments. Copepod size-at-immature stage significantly increased in cold treatments, while adult size significantly decreased in warm treatments. PMID:25413864

Garzke, Jessica; Ismar, Stefanie M H; Sommer, Ulrich

2014-11-21

125

Climate Response of the Equatorial Pacific to Global Warming.  

E-print Network

??The climate response of the equatorial Pacific to increased greenhouse gases is investigated using numerical experiments from five climate models participating in the Intergovernmental Panel… (more)

Di Nezio, Pedro N.

2008-01-01

126

Warm Eocene climate enhanced petroleum generation from Cretaceous source rocks - a potential climate feedback mechanism?  

NASA Astrophysics Data System (ADS)

Surface and deep sea temperatures from late Paleocene to early Eocene until the Early Eocene climatic Optimum increased by 5 - 10° C. This change was associated with a negative ?13C trend which implies major changes in global carbon cycling and enrichment of surface systems in isotopically light carbon. The degree of change in sedimentary ?13C requires emission of >10,000 gigatonnes of isotopically light carbon into the ocean. We reveal a relationship between global warming and increased petroleum generation in sedimentary basins operating on 100 kyr to Myr time scales that may explain the observed isotope shift. We use TEX86-based surface temperature data1 to predict how change in surface temperature influences the temperature evolution and resultant petroleum generation in four southwest Pacific sedimentary basins. Models predict an up to 50% increase in oil and gas expulsion rates in response to the increase in temperatures from late Paleocene to early Eocene in the region. Such an increase in petroleum generation would have significantly increased leakage of light hydrocarbons and oil degeneration products into surface systems. We propose that our modelling results are representative of a large number of sedimentary basins world-wide and that early Eocene warming has led to a synchronization of periods of maximum petroleum generation and enhanced generation in otherwise unproductive basins through extension of the volume of source rock within the oil and gas window. Extrapolating our modelling results to hundreds of sedimentary basins worldwide suggests that globally increased leakage could have led to the release of an amount of CH4, CO2 and light petroleum components into surface systems compatible with the observed changes in ?13C. We further suggest that this is a significant feedback effect, enhancing early Eocene climate warming. 1Bijl, P. K., S. Schouten, A. Sluijs, G.-J. Reichart, J. C. Zachos, and H. Brinkhuis (2009), Early Palaeogene temperature evolution of the southwest Pacific Ocean, Nature, 461, 776-779.

Kroeger, K. F.; Funnell, R. H.

2012-04-01

127

Warm rain processes over tropical oceans and climate implications  

Microsoft Academic Search

From analysis of TRMM data, we find that warm rain accounts for 31% of the total rain amount and 72% of the total rain area in the tropics, and plays an important role in regulating the moisture content of the tropical atmosphere. There is a substantial increase in precipitation efficiency of light warm rain as the sea surface temperature increases,

K. M. Lau; H. T. Wu

2003-01-01

128

Key constraints on Earth's climate during the mid-Pliocene Warm Period  

NASA Astrophysics Data System (ADS)

The study of warm intervals of the Pliocene Epoch (Pliocene 'interglacials') is important for understanding the long-term response of the Earth System to current or near future concentrations of atmospheric CO2; as well as global mean temperatures that will be attained during this century. The Pliocene can yield constraints on Earth System Sensitivity which would help identify a target CO2 threshold that must not be crossed if humankind is to avoid dangerous levels of climate change in the long-term. For this endeavour to succeed it requires the merger of globally distributed geological records of Pliocene environments with state-of-the-art climate and Earth System Models. These processes/products provide an extraordinary scientific resource for studying global and regional Pliocene environments and climate dynamics. However, from the perspective of the 5th Intergovernmental Panel on Climate Change Assessment Report, arguably some of most pressing questions to ask Pliocene climate researchers are (a) how much did global mean temperatures increase, (b) how is this increase expressed in reconstructions of meridional sea-surface and surface temperature gradients, and (c) how well can current climate models reproduce the observed trends in meridional temperature gradients. For the mid-Pliocene Warm Period (mPWP ~3.3 to 3.0 Ma BP) we present a comprehensive review of geologically-constrained climate model estimates of global temperature change available within the published literature. We also include data from recent simulations completed as part of international Pliocene Model Intercomparison Project. Our analysis focuses on the range in model estimated global temperature change as well as consistent differences in global temperature change observed between models which use prescribed sea surface and sea-ice boundary conditions from geological estimates, versus simulations in which these parameters are predicted by the models themselves. We present a new reconstruction of the meridional sea-surface temperature (SST) gradient for the mPWP that places confidence limits on proxy-based SSTs for the first time. This step is essential to robustly evaluate the ability of models to reproduce warm climate states during the Pliocene. Initial interrogation of three world leading climate models (UK Hadley Centre HadCM3, NCAR-CCSM4 and GISS Model-E) indicates broad agreement between the models and proxy data in the tropics and Southern Hemisphere, but highlights a consistent underestimation of SST change by the models in the North Atlantic. This study provides the necessary scientific foundation for a focussed campaign of model sensitivity experiments to determine if these errors can be eliminated or reduced within the limits of our current understanding of Pliocene geological boundary conditions (e.g. CO2, palaeobathymetry etc.) as well as model capabilities.

Haywood, A. M.; Dowsett, H. J.; Otto-Bliesner, B. L.; Chandler, M. A.; Naish, T.; Lunt, D. J.

2011-12-01

129

Medical Providers as Global Warming and Climate Change Health Educators: A Health Literacy Approach  

ERIC Educational Resources Information Center

Climate change is a threat to wildlife and the environment, but it also one of the most pervasive threats to human health. The goal of this study was to examine the relationships among dimensions of health literacy, patient education about global warming and climate change (GWCC), and health behaviors. Results reveal that patients who have higher…

Villagran, Melinda; Weathers, Melinda; Keefe, Brian; Sparks, Lisa

2010-01-01

130

Climate warming and the decline of amphibians and reptiles in Europe  

E-print Network

SPECIAL ISSUE Climate warming and the decline of amphibians and reptiles in Europe M. B. Arau´jo1 the relationship between current European distributions of amphibian and reptile species and observed climate ask, first, what proportion of amphibian and reptile species are projected to lose and gain suitable

Binford, Michael W.

131

Climate Warming, Marine Protected Areas and the Ocean-Scale Integrity of Coral Reef Ecosystems  

Microsoft Academic Search

Coral reefs have emerged as one of the ecosystems most vulnerable to climate variation and change. While the contribution of a warming climate to the loss of live coral cover has been well documented across large spatial and temporal scales, the associated effects on fish have not. Here, we respond to recent and repeated calls to assess the importance of

Nicholas A. J. Graham; Tim R. McClanahan; M. Aaron MacNeil; Shaun K. Wilson; Nicholas V. C. Polunin; Simon Jennings; Pascale Chabanet; Susan Clark; Mark D. Spalding; Yves Letourneur; Lionel Bigot; René Galzin; Marcus C. Öhman; Kajsa C. Garpe; Alasdair J. Edwards; Charles R. C. Sheppard

2008-01-01

132

Climate-change impact potentials as an alternative to global warming potentials  

NASA Astrophysics Data System (ADS)

For policy applications, such as for the Kyoto Protocol, the climate-change contributions of different greenhouse gases are usually quantified through their global warming potentials. They are calculated based on the cumulative radiative forcing resulting from a pulse emission of a gas over a specified time period. However, these calculations are not explicitly linked to an assessment of ultimate climate-change impacts. A new metric, the climate-change impact potential (CCIP), is presented here that is based on explicitly defining the climate-change perturbations that lead to three different kinds of climate-change impacts. These kinds of impacts are: (1) those related directly to temperature increases; (2) those related to the rate of warming; and (3) those related to cumulative warming. From those definitions, a quantitative assessment of the importance of pulse emissions of each gas is developed, with each kind of impact assigned equal weight for an overall impact assessment. Total impacts are calculated under the RCP6 concentration pathway as a base case. The relevant climate-change impact potentials are then calculated as the marginal increase of those impacts over 100 years through the emission of an additional unit of each gas in 2010. These calculations are demonstrated for CO2, methane and nitrous oxide. Compared with global warming potentials, climate-change impact potentials would increase the importance of pulse emissions of long-lived nitrous oxide and reduce the importance of short-lived methane.

Kirschbaum, Miko U. F.

2014-03-01

133

Energy-balance mechanisms underlying consistent large-scale temperature responses in warm and cold climates  

NASA Astrophysics Data System (ADS)

Climate simulations show consistent large-scale temperature responses including amplified land-ocean contrast, high-latitude/low-latitude contrast, and changes in seasonality in response to year-round forcing, in both warm and cold climates, and these responses are proportional and nearly linear across multiple climate states. We examine the possibility that a small set of common mechanisms controls these large-scale responses using a simple energy-balance model to decompose the temperature changes shown in multiple lgm and abrupt4 × CO 2 simulations from the CMIP5 archive. Changes in the individual components of the energy balance are broadly consistent across the models. Although several components are involved in the overall temperature responses, surface downward clear-sky longwave radiation is the most important component driving land-ocean contrast and high-latitude amplification in both warm and cold climates. Surface albedo also plays a significant role in promoting high-latitude amplification in both climates and in intensifying the land-ocean contrast in the warm climate case. The change in seasonality is a consequence of the changes in land-ocean and high-latitude/low-latitude contrasts rather than an independent temperature response. This is borne out by the fact that no single component stands out as being the major cause of the change in seasonality, and the relative importance of individual components is different in cold and warm climates.

Izumi, Kenji; Bartlein, Patrick J.; Harrison, Sandy P.

2014-06-01

134

Ocean Conditions, Salmon, and Climate Change  

E-print Network

Ocean Conditions, Salmon, and Climate Change John Ferguson1 NOAA Fisheries Northwest Fisheries;Today's talk · Past (why study the ocean?) · Present (how we study the ocean) · Future (what we're finding - adult forecasts and climate change) #12;1. Past (for context) · The coastal pelagic ecosystem

135

Expanding Peatlands in Alaska Caused by Accelerated Glacier Melting Under a Warming Climate  

NASA Astrophysics Data System (ADS)

Most mountain glaciers worldwide have been retreating over the last century due to global warming. This is particularly true around the Gulf of Alaska, where glacier recession has further accelerated since 1988. It is well known that glacier meltwater plays a critical role in the global sea level rise, but its effects on structure and functioning of peatland ecosystems remain poorly understood. We have observed in the field that many peatlands in the Susitna Basin, south-central Alaska, are expanding. As high moisture conditions are needed to promote peatland development and expansion, a regional change toward wetter conditions is likely responsible for the ongoing paludification of these peatlands. However, instrumental climatic data from this region show no increase in precipitation but an increase in temperature (and presumably evaporation) over the last decades. We hypothesize that climatically-induced glacier melting is modifying the local/regional climate, especially air humidity during the growing season, promoting the expansion of peatlands. To document recent peatland vertical growth and lateral expansion, we collected two long peat cores and twelve 30-cm-long monoliths in 2008 along a 110-m transect from an expanding peatland margin toward the peatland center. Ecohydrologic changes were reconstructed from testate amoebae and plant macrofossils assemblages. Preliminary results from both long cores revealed a change in the vegetation assemblages from a mesotrophic fen dominated by sedges and brown mosses to a Sphagnum-dominated peat bog at 11 cm, suggesting a very recent modification of the local hydrologic regime. A simultaneous increase in moisture was reconstructed from testate amoebae records. These unusual shifts in peatland development and hydrology (e.g., wet conditions triggering the fen-bog transition) imply a recent increase of atmospheric water to these peatlands. Our ongoing lead-210 dating and additional proxy analysis will help us resolve the timing and nature of recent peatland changes. These data, together with glacier history and climate records, will allow us to further test our hypothesis that the increase in glacier meltwater is causing peatland expansion By acting as water sinks, peatlands located in glacierized watersheds may mediate the contribution of meltwater to present and future sea-level rise. Increases in peat accumulation rates due to favorable hydroclimatic conditions are also expected to promote carbon sequestration by these ecosystems. In contrast to the expected desiccation of peatlands under a warmer climate, enhanced growth due to glaciers-climate feedbacks in high-latitude regions may thus promote peatland expansion, even just temporally.

Loisel, J.; Yu, Z.; Jones, M. C.

2009-05-01

136

Constant diurnal temperature regime alters the impact of simulated climate warming on a tropical pseudoscorpion  

NASA Astrophysics Data System (ADS)

Recent theory suggests that global warming may be catastrophic for tropical ectotherms. Although most studies addressing temperature effects in ectotherms utilize constant temperatures, Jensen's inequality and thermal stress considerations predict that this approach will underestimate warming effects on species experiencing daily temperature fluctuations in nature. Here, we tested this prediction in a neotropical pseudoscorpion. Nymphs were reared in control and high-temperature treatments under a constant daily temperature regime, and results compared to a companion fluctuating-temperature study. At constant temperature, pseudoscorpions outperformed their fluctuating-temperature counterparts. Individuals were larger, developed faster, and males produced more sperm, and females more embryos. The greatest impact of temperature regime involved short-term, adult exposure, with constant temperature mitigating high-temperature effects on reproductive traits. Our findings demonstrate the importance of realistic temperature regimes in climate warming studies, and suggest that exploitation of microhabitats that dampen temperature oscillations may be critical in avoiding extinction as tropical climates warm.

Zeh, Jeanne A.; Bonilla, Melvin M.; Su, Eleanor J.; Padua, Michael V.; Anderson, Rachel V.; Zeh, David W.

2014-01-01

137

Constant diurnal temperature regime alters the impact of simulated climate warming on a tropical pseudoscorpion  

PubMed Central

Recent theory suggests that global warming may be catastrophic for tropical ectotherms. Although most studies addressing temperature effects in ectotherms utilize constant temperatures, Jensen's inequality and thermal stress considerations predict that this approach will underestimate warming effects on species experiencing daily temperature fluctuations in nature. Here, we tested this prediction in a neotropical pseudoscorpion. Nymphs were reared in control and high-temperature treatments under a constant daily temperature regime, and results compared to a companion fluctuating-temperature study. At constant temperature, pseudoscorpions outperformed their fluctuating-temperature counterparts. Individuals were larger, developed faster, and males produced more sperm, and females more embryos. The greatest impact of temperature regime involved short-term, adult exposure, with constant temperature mitigating high-temperature effects on reproductive traits. Our findings demonstrate the importance of realistic temperature regimes in climate warming studies, and suggest that exploitation of microhabitats that dampen temperature oscillations may be critical in avoiding extinction as tropical climates warm. PMID:24424082

Zeh, Jeanne A.; Bonilla, Melvin M.; Su, Eleanor J.; Padua, Michael V.; Anderson, Rachel V.; Zeh, David W.

2014-01-01

138

Evidence for 20th century climate warming and wetland drying in the North American Prairie Pothole Region  

USGS Publications Warehouse

The Prairie Pothole Region (PPR) of North America is a globally important resource that provides abundant and valuable ecosystem goods and services in the form of biodiversity, groundwater recharge, water purification, flood attenuation, and water and forage for agriculture. Numerous studies have found these wetlands, which number in the millions, to be highly sensitive to climate variability. Here, we compare wetland conditions between two 30-year periods (1946–1975; 1976–2005) using a hindcast simulation approach to determine if recent climate warming in the region has already resulted in changes in wetland condition. Simulations using the WETLANDSCAPE model show that 20th century climate change may have been sufficient to have a significant impact on wetland cover cycling. Modeled wetlands in the PPR's western Canadian prairies show the most dramatic effects: a recent trend toward shorter hydroperiods and less dynamic vegetation cycles, which already may have reduced the productivity of hundreds of wetland-dependent species.

Werner, B.A.; Johnson, W. Carter; Guntenspergen, Glenn R.

2013-01-01

139

Enhanced marine productivity off western North America during warm climate intervals of the past 52 k.y  

USGS Publications Warehouse

Studies of the Santa Barbara Basin off the coast of California have linked changes in its bottom-water oxygen content to millennial-scale climate changes as recorded by the oxygen isotope composition of Greenland ice. Through the use of detailed records from a sediment core collected off the Magdalena Margin of Baja California, Mexico, we demonstrate that this teleconnection predominantly arose from changes in marine productivity, rather than changes in ventilation of the North Pacific, as was originally proposed. One possible interpretation is that the modern balance of El Nin??o-La Nin??a conditions that favors a shallow nutricline and high productivity today and during warm climate intervals of the past 52 k.y. was altered toward more frequent, deep nutricline, low productivity, El Nin??o-like conditions during cool climate intervals. ?? 2004 Geological Society of America.

Ortiz, J.D.; O'Connell, S. B.; DelViscio, J.; Dean, W.; Carriquiry, J.D.; Marchitto, T.; Zheng, Y.; VanGeen, A.

2004-01-01

140

Evidence for 20th century climate warming and wetland drying in the North American Prairie Pothole Region  

PubMed Central

The Prairie Pothole Region (PPR) of North America is a globally important resource that provides abundant and valuable ecosystem goods and services in the form of biodiversity, groundwater recharge, water purification, flood attenuation, and water and forage for agriculture. Numerous studies have found these wetlands, which number in the millions, to be highly sensitive to climate variability. Here, we compare wetland conditions between two 30-year periods (1946–1975; 1976–2005) using a hindcast simulation approach to determine if recent climate warming in the region has already resulted in changes in wetland condition. Simulations using the WETLANDSCAPE model show that 20th century climate change may have been sufficient to have a significant impact on wetland cover cycling. Modeled wetlands in the PPR's western Canadian prairies show the most dramatic effects: a recent trend toward shorter hydroperiods and less dynamic vegetation cycles, which already may have reduced the productivity of hundreds of wetland-dependent species. PMID:24223283

Werner, Brett A; Johnson, W Carter; Guntenspergen, Glenn R

2013-01-01

141

A new climate dataset for systematic assessments of climate change impacts as a function of global warming  

NASA Astrophysics Data System (ADS)

In the ongoing political debate on climate change, global mean temperature change (?Tglob) has become the yardstick by which mitigation costs, impacts from unavoided climate change, and adaptation requirements are discussed. For a scientifically informed discourse along these lines, systematic assessments of climate change impacts as a function of ?Tglob are required. The current availability of climate change scenarios constrains this type of assessment to a narrow range of temperature change and/or a reduced ensemble of climate models. Here, a newly composed dataset of climate change scenarios is presented that addresses the specific requirements for global assessments of climate change impacts as a function of ?Tglob. A pattern-scaling approach is applied to extract generalised patterns of spatially explicit change in temperature, precipitation and cloudiness from 19 Atmosphere-Ocean General Circulation Models (AOGCMs). The patterns are combined with scenarios of global mean temperature increase obtained from the reduced-complexity climate model MAGICC6 to create climate scenarios covering warming levels from 1.5 to 5 degrees above pre-industrial levels around the year 2100. The patterns are shown to sufficiently maintain the original AOGCMs' climate change properties, even though they, necessarily, utilise a simplified relationships between ?Tglob and changes in local climate properties. The dataset (made available online upon final publication of this paper) facilitates systematic analyses of climate change impacts as it covers a wider and finer-spaced range of climate change scenarios than the original AOGCM simulations.

Heinke, J.; Ostberg, S.; Schaphoff, S.; Frieler, K.; Müller, C.; Gerten, D.; Meinshausen, M.; Lucht, W.

2013-10-01

142

Definitions of climate and climate change under varying external conditions  

NASA Astrophysics Data System (ADS)

Commonly, definitions of climate are endorsed where the external conditions are held constant. This paper argues that these definitions risk being empirically void because in reality the external conditions vary. As a consequence, analogous definitions for varying external conditions are explored with help of the recently developed theory of non-autonomous dynamical systems, and the similarities and differences between the cases of constant and varying external conditions are discussed. It is argued that there are analogous definitions for varying external conditions which are preferable to the definitions where the external conditions are held constant. In this context, a novel definition is proposed (namely, climate as the distribution over time under a regime of varying external conditions), which is argued to be promising.

Werndl, C.

2014-06-01

143

Climatic features of summer temperature in northeast china under warming background  

Microsoft Academic Search

By using, summer temperature data in 26 stations from 1951 to 2003, the variation characteristics of summer temperature in\\u000a Northeast China (NET) were analyzed based on the background of climate warming. The results showed that the warming in summer\\u000a was 0.15?C\\/10a in Northeast China, which was higher than that on the global, Northern Hemisphere or Northeast Asia scale in\\u000a the

Ji Li; Qiang Gong; Lian-wei Zhao

2005-01-01

144

Nutritional requirements of sheep, goats and cattle in warm climates: a meta-analysis.  

PubMed

The objective of the study was to update energy and protein requirements of growing sheep, goats and cattle in warm areas through a meta-analysis study of 590 publications. Requirements were expressed on metabolic live weight (MLW=LW0.75) and LW1 basis. The maintenance requirements for energy were 542.64 and 631.26 kJ ME/kg LW0.75 for small ruminants and cattle, respectively, and the difference was significant (P<0.01). The corresponding requirement for 1 g gain was 24.3 kJ ME without any significant effect of species. Relative to LW0.75, there was no difference among genotypes intra-species in terms of ME requirement for maintenance and gain. However, small ruminants of warm and tropical climate appeared to have higher ME requirements for maintenance relative to live weight (LW) compared with temperate climate ones and cattle. Maintenance requirements for protein were estimated via two approaches. For these two methods, the data in which retained nitrogen (RN) was used cover the same range of variability of observations. The regression of digestible CP intake (DCPI, g/kg LW0.75) against RN (g/kg LW0.75) indicated that DCP requirements are significantly higher in sheep (3.36 g/kg LW0.75) than in goats (2.38 g/kg LW0.75), with cattle intermediate (2.81 g/kg LW0.75), without any significant difference in the quantity of DCPI/g retained CP (RCP) (40.43). Regressing metabolisable protein (MP) or minimal digestible protein in the intestine (PDImin) against RCP showed that there was no difference between species and genotypes, neither for the intercept (maintenance=3.51 g/kg LW0.75 for sheep and goat v. 4.35 for cattle) nor for the slope (growth=0.60 g MP/g RCP). The regression of DCP against ADG showed that DCP requirements did not differ among species or genotypes. These new feeding standards are derived from a wider range of nutritional conditions compared with existing feeding standards as they are based on a larger database. The standards seem to be more appropriate for ruminants in warm and tropical climates around the world. PMID:24902005

Salah, N; Sauvant, D; Archimède, H

2014-09-01

145

Link between land-ocean warming contrast and surface relative humidities in simulations with coupled climate models  

E-print Network

Simulations of warming climates with coupled climate models exhibit strong land-ocean contrasts in changes in surface temperature and relative humidity, but little land-ocean contrast in changes in equivalent potential ...

Byrne, Michael Patrick

146

The Early Climate History of Mars: "Warm and Wet" or "Cold and Icy"?  

NASA Astrophysics Data System (ADS)

The Amazonian climate (last ~66% of history) was much like today, a cold and dry climate regime, characterized by the latitudinal migration of surface ice in response to variations in spin-axis/orbital parameters. But what characterized the Noachian climate (first ~20% of history)? Some data support a "warm and wet" early Mars, but this evidence has been challenged. New models of early Mars climate (Forget, Wordsworth et al.) find that for atmospheric pressures greater than a few hundred millibars, surface temperatures vary with altitude due to atmosphere-surface thermal coupling: an adiabatic cooling effect (ACE) results in deposition of snow and ice at high altitudes, in contrast to Amazonian conditions. Without other warming mechanisms, no combination of parameters lead to mean annual surface temperatures (MAT) consistent with widespread liquid water anywhere on the planet. The ACE causes southern highland region temperatures to fall significantly below the global average leading to a "Noachian Icy Highlands" scenario: Water is transported to the highlands from low-lying regions due to the ACE and snows out to form an extended H2O ice cap at the southern pole, and altitude-dependent snow and ice deposits down to lower southern latitudes. Could the predictions of this "Noachian Icy Highlands" model be consistent with the many lines of evidence traditionally cited for a "warm, wet" early Mars? Perturbing this predominant Noachian environment with punctuated impacts and volcanism/greenhouse gases would lead to raising of global surface temperatures toward the melting point of water, with the following consequences: 1) ice above the surface ice stability line undergoes rapid altitude/latitude dependent warming during each Mars summer; 2) meltwater runoff from the continuous ice sheet drains and flows downslope to the edge of the ice sheet, where meltwater channels encounter cratered terrain, forming closed-basin and open-basin lakes; 3) seasonal top-down heating and melting of the top tens of meters of continuous ice produce a volume of water well in excess of the total volume interpreted to have occupied open-basin/closed basin lakes; 4) this meltwater initially erodes into the dry regolith down to the top of the ice table, producing a perched aquifer and more efficient erosion than infiltration alone; 5) at the end of the annual melting period, temperatures return to below 0°C, meltwater freezes and sublimes, returning to high altitudes as snowfall to replenish the snow and ice deposit; 6) this Noachian icy highlands, ACE-dominated water cycle persists until MAT drops to <0°C. The icy Noachian highlands/punctuated volcanism scenario appears to be able to account for the: 1) source and volume of water required for valley networks; 2) presence of closed/open-basin lakes; 4) evidence for recurring phases of activity over millions of years; 5) small amounts of net erosion; 6) relatively poor stream integration and lower order; 7) presence of a surface hydrological cycle that can replenish the source area and cause recurring activity with a small total budget of water; and 8) presence of melting and runoff in a Late Noachian climate compatible with other constraints (e.g., faint young Sun, low atmospheric pressure).

Head, James

2013-04-01

147

Climatic Warming Increases Winter Wheat Yield but Reduces Grain Nitrogen Concentration in East China  

PubMed Central

Climatic warming is often predicted to reduce wheat yield and grain quality in China. However, direct evidence is still lacking. We conducted a three-year experiment with a Free Air Temperature Increase (FATI) facility to examine the responses of winter wheat growth and plant N accumulation to a moderate temperature increase of 1.5°C predicted to prevail by 2050 in East China. Three warming treatments (AW: all-day warming; DW: daytime warming; NW: nighttime warming) were applied for an entire growth period. Consistent warming effects on wheat plant were recorded across the experimental years. An increase of ca. 1.5°C in daily, daytime and nighttime mean temperatures shortened the length of pre-anthesis period averagely by 12.7, 8.3 and 10.7 d (P<0.05), respectively, but had no significant impact on the length of the post-anthesis period. Warming did not significantly alter the aboveground biomass production, but the grain yield was 16.3, 18.1 and 19.6% (P<0.05) higher in the AW, DW and NW plots than the non-warmed plot, respectively. Warming also significantly increased plant N uptake and total biomass N accumulation. However, warming significantly reduced grain N concentrations while increased N concentrations in the leaves and stems. Together, our results demonstrate differential impacts of warming on the depositions of grain starch and protein, highlighting the needs to further understand the mechanisms that underlie warming impacts on plant C and N metabolism in wheat. PMID:24736557

Deng, Aixing; Song, Zhenwei; Zhang, Baoming; Zhang, Weijian

2014-01-01

148

Warm Rain Processes Over the Tropical Oceans and Implications on Climate Change  

NASA Technical Reports Server (NTRS)

In this talk, we will first show results from TRMM regarding the characteristics of warm rains over the tropical oceans, and the dependence of rate of warm rain production on sea surface temperature. Results lead to the hypothesis that warm rain production efficiency, i.e., autoconversion, may be increased in a warm climate. We use the GEOS-II GCM to test this hypothesis. Our modeling results show that in a climate with increased rate of autoconversion, the total rain amount is increased, with warm rain contributing to a larger portion of the increase. The abundant rainout of warm precipitation at middle to low levels causes a reduction of high cloud cover due to the depletion of water available for ice-phase rain production. As a result, more isolated, but more intense penetrative convection develops. Results also show that increased autoconversion reduces the convective adjustment time scale tends, implying a faster recycling of atmospheric water. Most interestingly, the increased low level heating associated with warm rain leads to more energetic Madden and Julian oscillations in the tropics, with well-defined eastward propagation. While reducing the autoconversion leads to an abundant mix of westward and eastward tropical disturbance on daily to weekly time scales. The causes of the sensitivity of the dynamical regimes to the microphysics parameterization in the GCM will be discussed.

Lau, William K. M.; Wu, H. T.

2004-01-01

149

Climate warming mediates negative impacts of rapid pond drying for three amphibian species.  

PubMed

Anthropogenic climate change will present both opportunities and challenges for pool-breeding amphibians. Increased water temperature and accelerated drying may directly affect larval growth, development, and survival, yet the combined effects of these processes on larvae with future climate change remain poorly understood. Increased surface temperatures are projected to warm water and decrease water inputs, leading to earlier and faster wetland drying. So it is often assumed that larvae will experience negative synergistic impacts with combined warming and drying. However, an alternative hypothesis is that warming-induced increases in metabolic rate and aquatic resource availability might compensate for faster drying rates, generating antagonistic larval responses. We conducted a mesocosm experiment to test the individual and interactive effects of pool permanency (permanent vs. temporary) and water temperature (ambient vs. (+) -3 degrees C) on three anurans with fast-to-slow larval development rates (Great Basin spadefoot [Spea intermontana], Pacific chorus frog [Pseudacris regilla], and northern red-legged frog [Rana aurora]). We found that although tadpoles in warmed pools reached metamorphosis 15-17 days earlier, they did so with little cost (< 2 mm) to size, likely due to greater periphyton growth in warmed pools easing drying-induced resource competition. Warming and drying combined to act antagonistically on early growth (P = 0.06) and survival (P = 0.06), meaning the combined impact was less than the sum of the individual impacts. Warming and drying acted additively on time to and size at metamorphosis. These nonsynergistic impacts may result from cotolerance of larvae to warming and drying, as well as warming helping to offset negative impacts of drying. Our results indicate that combined pool warming and drying may not always be harmful for larval amphibians. However, they also demonstrate that antagonistic responses are difficult to predict, which poses a challenge to proactive conservation and management. Our study highlights the importance of considering the nature of multiple stressor interactions as amphibians are exposed to an increasing number of anthropogenic threats. PMID:24933805

O'Regan, Sacha M; Palen, Wendy J; Anderson, Sean C

2014-04-01

150

Reconstruction of spatial patterns of climatic anomalies during the medieval warm period (AD 900-1300)  

SciTech Connect

The workshop will focus on climatic variations during the Medieval Warm Period or Little Climatic Optimum. The nominal time interval assigned to this period is AD 900--1300, but climate information available during the century or two preceding and following this episode is welcome. The aims of the workshop will be to: examine the available evidence for the existence of this episode; assess the spatial and temporal synchronicity of the climatic signals; discuss possible forcing mechanisms; and identify areas and paleoenvironmental records where additional research efforts are needed to improve our knowledge of this period. This document consists of abstracts of eighteen papers presented at the meeting.

Diaz, H.F. [National Oceanic and Atmospheric Administration, Boulder, CO (United States). Environmental Research Labs.; Hughes, M.K. [Arizona Univ., Tucson, AZ (United States). Lab. of Tree-Ring Research

1992-12-31

151

On the Predictive Landslide Susceptibility Under Climate Change Conditions  

NASA Astrophysics Data System (ADS)

Among the most critical issues, climate abnormalities caused by global warming also affect Taiwan significantly for the past decade. The frequency of extreme rainfall events has increased, where the concentrated and heavy rainfalls generally caused geohazards, including landslides and debris flows. Based on the rainfall data collected, this study employs rainfall frequency analysis and the domestic atmosphere general circulation model (AGCM) downscaling estimates to understand the past rainfall pattern and forecast the future rainfall trends, distributions, and the intensities. In this study, the Chingshui River Watershed, a watershed with major geohazards in Taiwan, was adopted as the study area. Rainfall estimates from the rainfall frequency analysis and AGCM were used in the susceptibility model to produce susceptibility zoning maps for various rainfall scenarios under climate change conditions. The results suggest the areas with high hazard potential, and the susceptibility maps can be used for disaster remediation, mitigation, and prevention plan for the study area.

Shou, Keh-Jian

2014-05-01

152

Communicating Climate Uncertainties: Challenges and Opportunities Related to Spatial Scales, Extreme Events, and the Warming 'Hiatus'  

NASA Astrophysics Data System (ADS)

Many media, academic, government, and advocacy organizations have achieved sophistication in developing effective messages based on scientific information, and can quickly translate salient aspects of emerging climate research and evolving observations. However, there are several ways in which valid messages can be misconstrued by decision makers, leading them to inaccurate conclusions about the risks associated with climate impacts. Three cases will be discussed: 1) Issues of spatial scale in interpreting climate observations: Local climate observations may contradict summary statements about the effects of climate change on larger regional or global spatial scales. Effectively addressing these differences often requires communicators to understand local and regional climate drivers, and the distinction between a 'signal' associated with climate change and local climate 'noise.' Hydrological statistics in Missouri and California are shown to illustrate this case. 2) Issues of complexity related to extreme events: Climate change is typically invoked following a wide range of damaging meteorological events (e.g., heat waves, landfalling hurricanes, tornadoes), regardless of the strength of the relationship between anthropogenic climate change and the frequency or severity of that type of event. Examples are drawn from media coverage of several recent events, contrasting useful and potentially confusing word choices and frames. 3) Issues revolving around climate sensitivity: The so-called 'pause' or 'hiatus' in global warming has reverberated strongly through political and business discussions of climate change. Addressing the recent slowdown in warming yields an important opportunity to raise climate literacy in these communities. Attempts to use recent observations as a wedge between climate 'believers' and 'deniers' is likely to be counterproductive. Examples are drawn from Congressional testimony and media stories. All three cases illustrate ways that decision makers can arrive at invalid conclusions from a seemingly valid scientific messages. Honest discussion of uncertainties, and recognition of the spatial and time scales associated with decision making, can work to combat this potential confusion.

Casola, J. H.; Huber, D.

2013-12-01

153

WHAT TO DO ABOUT CLIMATE CHANGE? Slowing the rate of carbon burning won't stop global warming  

E-print Network

WHAT TO DO ABOUT CLIMATE CHANGE? #12;Slowing the rate of carbon burning won't stop global warming: most CO2 stays in the air over a century, though individual molecules come and go. Global warming. But we need to research it -- starting now. If global warming gets bad, public opinion may suddently flip

Baez, John

154

A new dataset for systematic assessments of climate change impacts as a function of global warming  

NASA Astrophysics Data System (ADS)

In the ongoing political debate on climate change, global mean temperature change (?Tglob) has become the yardstick by which mitigation costs, impacts from unavoided climate change, and adaptation requirements are discussed. For a scientifically informed discourse along these lines systematic assessments of climate change impacts as a function of ?Tglob are required. The current availability of climate change scenarios constrains this type of assessment to a~narrow range of temperature change and/or a reduced ensemble of climate models. Here, a newly composed dataset of climate change scenarios is presented that addresses the specific requirements for global assessments of climate change impacts as a function of ?Tglob. A pattern-scaling approach is applied to extract generalized patterns of spatially explicit change in temperature, precipitation and cloudiness from 19 AOGCMs. The patterns are combined with scenarios of global mean temperature increase obtained from the reduced-complexity climate model MAGICC6 to create climate scenarios covering warming levels from 1.5 to 5 degrees above pre-industrial levels around the year 2100. The patterns are shown to sufficiently maintain the original AOGCMs' climate change properties, even though they, necessarily, utilize a simplified relationships between?Tglob and changes in local climate properties. The dataset (made available online upon final publication of this paper) facilitates systematic analyses of climate change impacts as it covers a wider and finer-spaced range of climate change scenarios than the original AOGCM simulations.

Heinke, J.; Ostberg, S.; Schaphoff, S.; Frieler, K.; M{ü}ller, C.; Gerten, D.; Meinshausen, M.; Lucht, W.

2012-11-01

155

Soil respiration under climate change: prolonged summer drought offsets soil warming effects  

PubMed Central

Climate change may considerably impact the carbon (C) dynamics and C stocks of forest soils. To assess the combined effects of warming and reduced precipitation on soil CO2 efflux, we conducted a two-way factorial manipulation experiment (4 °C soil warming + throughfall exclusion) in a temperate spruce forest from 2008 until 2010. Soil was warmed by heating cables throughout the growing seasons. Soil drought was simulated by throughfall exclusions with three 100 m2 roofs during 25 days in July/August 2008 and 2009. Soil warming permanently increased the CO2 efflux from soil, whereas throughfall exclusion led to a sharp decrease in soil CO2 efflux (45% and 50% reduction during roof installation in 2008 and 2009, respectively). In 2008, CO2 efflux did not recover after natural rewetting and remained lowered until autumn. In 2009, CO2 efflux recovered shortly after rewetting, but relapsed again for several weeks. Drought offset the increase in soil CO2 efflux by warming in 2008 (growing season CO2 efflux in t C ha?1: control: 7.1 ± 1.0; warmed: 9.5 ± 1.7; warmed + roof: 7.4 ± 0.3; roof: 5.9 ± 0.4) and in 2009 (control: 7.6 ± 0.8; warmed + roof: 8.3 ± 1.0). Throughfall exclusion mainly affected the organic layer and the top 5 cm of the mineral soil. Radiocarbon data suggest that heterotrophic and autotrophic respiration were affected to the same extent by soil warming and drying. Microbial biomass in the mineral soil (0–5 cm) was not affected by the treatments. Our results suggest that warming causes significant C losses from the soil as long as precipitation patterns remain steady at our site. If summer droughts become more severe in the future, warming induced C losses will likely be offset by reduced soil CO2 efflux during and after summer drought.

Schindlbacher, Andreas; Wunderlich, Steve; Borken, Werner; Kitzler, Barbara; Zechmeister-Boltenstern, Sophie; Jandl, Robert

2012-01-01

156

Air pollution control and decreasing new particle formation lead to strong climate warming  

NASA Astrophysics Data System (ADS)

The number concentration of cloud droplets determines several climatically relevant cloud properties. A major cause for the high uncertainty in the indirect aerosol forcing is the availability of cloud condensation nuclei (CCN), which in turn is highly sensitive to atmospheric new particle formation. Here we present the effect of new particle formation on anthropogenic aerosol forcing in present-day (year 2000) and future (year 2100) conditions. The present-day total aerosol forcing is increased from -1.0 W m-2 to -1.6 W m-2 when nucleation is introduced into the model. Nucleation doubles the change in aerosol forcing between years 2000 and 2100, from +0.6 W m-2 to +1.4 W m-2. Two climate feedbacks are studied, resulting in additional negative forcings of -0.1 W m-2 (+10% DMS emissions in year 2100) and -0.5 W m-2 (+50% BVOC emissions in year 2100). With the total aerosol forcing diminishing in response to air pollution control measures taking effect, warming from increased greenhouse gas concentrations can potentially increase at a very rapid rate.

Makkonen, R.; Asmi, A.; Kerminen, V.-M.; Boy, M.; Arneth, A.; Hari, P.; Kulmala, M.

2012-02-01

157

Understanding and partitioning future climates for Australian regions from CMIP3 using ocean warming indices  

Microsoft Academic Search

The patterns of large-scale climate change over the 21st century simulated by 23 CMIP3 global climate models are analyzed\\u000a to provide understanding of the range of projected temperature T and precipitation P changes for Australia published in 2007. Means of change, standardized by the global warming, within each of 11 regions are\\u000a calculated for each model. Correlations between regions across

Ian Geoffrey Watterson

2012-01-01

158

Ecosystem resilience despite large-scale altered hydro climatic conditions  

Technology Transfer Automated Retrieval System (TEKTRAN)

Climate change is predicted to increase both drought frequency and duration, and when coupled with substantial warming, will establish a new hydroclimatological paradigm for many regions. Large-scale, warm droughts have recently impacted North America, Africa, Europe, Amazonia, and Australia result...

159

Large impacts of climatic warming on growth of boreal forests since 1960.  

PubMed

Boreal forests are sensitive to climatic warming, because low temperatures hold back ecosystem processes, such as the mobilization of nitrogen in soils. A greening of the boreal landscape has been observed using remote sensing, and the seasonal amplitude of CO2 in the northern hemisphere has increased, indicating warming effects on ecosystem productivity. However, field observations on responses of ecosystem productivity have been lacking on a large sub-biome scale. Here we report a significant increase in the annual growth of boreal forests in Finland in response to climatic warming, especially since 1990. This finding is obtained by linking meteorological records and forest inventory data on an area between 60° and 70° northern latitude. An additional increase in growth has occurred in response to changes in other drivers, such as forest management, nitrogen deposition and/or CO2 concentration. A similar warming impact can be expected in the entire boreal zone, where warming takes place. Given the large size of the boreal biome - more than ten million km2- important climate feedbacks are at stake, such as the future carbon balance, transpiration and albedo. PMID:25383552

Kauppi, Pekka E; Posch, Maximilian; Pirinen, Pentti

2014-01-01

160

The effects of climate change due to global warming on river flows in Great Britain  

Microsoft Academic Search

Global warming due to an increasing concentration of greenhouse gases in the atmosphere will affect temperature and rainfall, and hence river flows and water resources. This paper presents results from an investigation into potential changes in river flows in 21 catchments in Great Britain, using a daily rainfall-runoff model and both equilibrium and transient climate change scenarios. Annual runoff was

N. W. Arnell; N. S. Reynard

1996-01-01

161

Mechanisms of Thermohaline Mode Switching with Application to Warm Equable Climates  

Microsoft Academic Search

A three-box model of haline and thermal mode overturning is developed to study thermohaline oscillations found in a number of ocean general circulation models and that might have occurred in warm equable paleo- climates. By including convective adjustment modified to represent the localized nature of deep convection, the box model shows that a steady haline mode circulation is unstable. For

Rong Zhang; Michael Follows; John Marshall

2002-01-01

162

Geothermal Evidence From Canada for a Cold Period Before Recent Climatic Warming  

Microsoft Academic Search

Three deep boreholes in a small area in Quebec, each having two high-accuracy temperature logs separated by 22 years, allow reliable determination of the ground surface temperature history during the past few centuries. The temperature logs show that the recent climatic warming was preceded by a cold period near the end of the 19th century in this area. The presence

Kelin Wang; Trevor J. Lewis

1992-01-01

163

Climate warming feedback from mountain birch forest expansion: reduced albedo dominates carbon uptake.  

PubMed

Expanding high-elevation and high-latitude forest has contrasting climate feedbacks through carbon sequestration (cooling) and reduced surface reflectance (warming), which are yet poorly quantified. Here, we present an empirically based projection of mountain birch forest expansion in south-central Norway under climate change and absence of land use. Climate effects of carbon sequestration and albedo change are compared using four emission metrics. Forest expansion was modeled for a projected 2.6 °C increase in summer temperature in 2100, with associated reduced snow cover. We find that the current (year 2000) forest line of the region is circa 100 m lower than its climatic potential due to land-use history. In the future scenarios, forest cover increased from 12% to 27% between 2000 and 2100, resulting in a 59% increase in biomass carbon storage and an albedo change from 0.46 to 0.30. Forest expansion in 2100 was behind its climatic potential, forest migration rates being the primary limiting factor. In 2100, the warming caused by lower albedo from expanding forest was 10 to 17 times stronger than the cooling effect from carbon sequestration for all emission metrics considered. Reduced snow cover further exacerbated the net warming feedback. The warming effect is considerably stronger than previously reported for boreal forest cover, because of the typically low biomass density in mountain forests and the large changes in albedo of snow-covered tundra areas. The positive climate feedback of high-latitude and high-elevation expanding forests with seasonal snow cover exceeds those of afforestation at lower elevation, and calls for further attention of both modelers and empiricists. The inclusion and upscaling of these climate feedbacks from mountain forests into global models is warranted to assess the potential global impacts. PMID:24343906

de Wit, Heleen A; Bryn, Anders; Hofgaard, Annika; Karstensen, Jonas; Kvalevåg, Maria M; Peters, Glen P

2014-07-01

164

Greenhouse warming: IPCC 1995 conclusions and assessment of climate models  

SciTech Connect

Implementation of the United Nations Framework Convention on Climate Change is at a crossroads. A few Parties have made a strong start, but most are lagging behind, waiting for someone lease to lead the way. Most industrialized countries have acknowledged that the current commitments in the Convention are inadequate in light of its objective of reducing global carbon dioxide emissions. The Berlin Climate Sunnit provides an opportunity for all industrialized countries to hold hands and jump forward together by agreeing on a binding emission reduction protocol. Only those countries which implement measures capable of creating structural change can be seen as taking the lead. Such measures, which include energy/COS taxes, Least-Cost Planning, and the redirection of transportation infrastructure investments, aim not only at returning greenhouse gas emissions to 1990 levels in 2000, but also at setting the stage for substantial reductions after the year 2000. If Parties take the Climate Convention seriously they must begin to make fundamental changes, not just slight adjustments to business as usual development patterns. The Berlin Climate Summit is a critical opportunity to move toward a sustainable trajectory.

Mahlman, J.

1995-12-31

165

Floods, Droughts and Global Warming: Rolling the Climate Dice  

NASA Astrophysics Data System (ADS)

In this study, we find from analyses of projections of 14 CMIP5 models a robust, canonical global response in rainfall characteristics to CO2 greenhouse warming. Under a scenario of 1% increase per year of CO2 emission, the model ensemble projects globally more heavy precipitation (+7×2.4%K-1), less moderate precipitation (-2.5×0.6%K-1), more light precipitation (+1.8×1.3%K-1), and increased length of dry (no-rain) periods (+4.7×2.1%K-1). Regionally, a majority of the models project a consistent response with more heavy precipitation over climatologically wet regions of the deep tropics especially the equatorial Pacific Ocean and the Asian monsoon regions, and more dry periods over the land areas of the subtropics and the tropical marginal convective zones. Changes in the global circulation associated with the precipitation changes include a narrowing and deepening of convective zone, a rise of the center of gravity and acceleration of the upper branch of the Hadley circulation, an expansion of the subtropics and a poleward shift of the jetstream. Our results suggest that increased risks of severe floods and droughts worldwide induced by increased CO2 emission is the manifestation of a canonical response of the global rainfall system in association with a re-adjustment of the global circulation system, in a competition for increased availability of atmospheric moisture from global warming.

Lau, W. K.; Wu, H.; Kim, K.

2013-12-01

166

Climate warming increases biological control agent impact on a non-target species  

PubMed Central

Climate change may shift interactions of invasive plants, herbivorous insects and native plants, potentially affecting biological control efficacy and non-target effects on native species. Here, we show how climate warming affects impacts of a multivoltine introduced biocontrol beetle on the non-target native plant Alternanthera sessilis in China. In field surveys across a latitudinal gradient covering their full distributions, we found beetle damage on A. sessilis increased with rising temperature and plant life history changed from perennial to annual. Experiments showed that elevated temperature changed plant life history and increased insect overwintering, damage and impacts on seedling recruitment. These results suggest that warming can shift phenologies, increase non-target effect magnitude and increase non-target effect occurrence by beetle range expansion to additional areas where A. sessilis occurs. This study highlights the importance of understanding how climate change affects species interactions for future biological control of invasive species and conservation of native species. PMID:25376303

Lu, Xinmin; Siemann, Evan; He, Minyan; Wei, Hui; Shao, Xu; Ding, Jianqing

2015-01-01

167

Climate warming increases biological control agent impact on a non-target species.  

PubMed

Climate change may shift interactions of invasive plants, herbivorous insects and native plants, potentially affecting biological control efficacy and non-target effects on native species. Here, we show how climate warming affects impacts of a multivoltine introduced biocontrol beetle on the non-target native plant Alternanthera sessilis in China. In field surveys across a latitudinal gradient covering their full distributions, we found beetle damage on A. sessilis increased with rising temperature and plant life history changed from perennial to annual. Experiments showed that elevated temperature changed plant life history and increased insect overwintering, damage and impacts on seedling recruitment. These results suggest that warming can shift phenologies, increase non-target effect magnitude and increase non-target effect occurrence by beetle range expansion to additional areas where A. sessilis occurs. This study highlights the importance of understanding how climate change affects species interactions for future biological control of invasive species and conservation of native species. PMID:25376303

Lu, Xinmin; Siemann, Evan; He, Minyan; Wei, Hui; Shao, Xu; Ding, Jianqing

2015-01-01

168

Climate conditions in bedded confinement buildings  

Technology Transfer Automated Retrieval System (TEKTRAN)

Confinement buildings are utilized for finishing cattle to allow more efficient collection of animal waste and to buffer animals against adverse climatic conditions. Environmental data were obtained from a 29 m wide x 318 m long bedded confinement building with the long axis oriented east to west. T...

169

An observational evidence of climate change during global warming era  

NASA Astrophysics Data System (ADS)

The relationships of the Frequency of the Cyclonic Systems (FCS) over the Bay of Bengal in the Summer Monsoon (SM) season (June through September) with the North Atlantic Oscillation Index (NAOI) and the Southern Oscillation Index (SOI) from January through May for the period 1950-2005 are examined. The NAOI (January and February) and the SOI (April) showed significant inverse and positive relationships respectively with the FCS generated in SM season over the Bay of Bengal. These relationships are marked on a decadal scale. In the Global Warming (GW) era, a significant reduction in the FCS is associated with a significant increase of NAOI, relaxation of SOI and a weak vertical zonal wind shear in the domain 5°-22°N and 80°-100°E.

Naidu, C. V.; Durgalakshmi, K.; Satyanarayana, G. Ch.; Rao, L. Malleswara; Ramakrishna, S. S. V. S.; Mohan, Jaddu Rama; Ratna, K. Naga

2011-10-01

170

Increases in flood magnitudes in California under warming climates  

USGS Publications Warehouse

Downscaled and hydrologically modeled projections from an ensemble of 16 Global Climate Models suggest that flooding may become more intense on the western slopes of the Sierra Nevada mountains, the primary source for California’s managed water system. By the end of the 21st century, all 16 climate projections for the high greenhouse-gas emission SRES A2 scenario yield larger floods with return periods ranging 2–50 years for both the Northern Sierra Nevada and Southern Sierra Nevada, regardless of the direction of change in mean precipitation. By end of century, discharges from the Northern Sierra Nevada with 50-year return periods increase by 30–90% depending on climate model, compared to historical values. Corresponding flood flows from the Southern Sierra increase by 50–100%. The increases in simulated 50 year flood flows are larger (at 95% confidence level) than would be expected due to natural variability by as early as 2035 for the SRES A2 scenario.

Das, Tapash; Maurer, Edwin P.; Pierce, David W.; Dettinger, Michael D.; Cayah, Daniel R.

2013-01-01

171

Personal efficacy, the information environment, and attitudes toward global warming and climate change in the united states. Risk Analysis  

E-print Network

Despite the growing scientific consensus about the risks of global warming and climate change, the mass media frequently portray the subject as one of great scientific controversy and debate. And yet previous studies of the mass public’s subjective assessments of the risks of global warming and climate change have not sufficiently examined public informedness, public confidence in climate scientists, and the role of personal efficacy in affecting global warming outcomes. By examining the results of a survey on an original and representative sample of Americans, we find that these three forces—informedness, confidence in scientists, and personal efficacy—are related in interesting and unexpected ways, and exert significant influence on risk assessments of global warming and climate change. In particular, more informed respondents both feel less personally responsible for global warming, and also show less concern for global warming. We also find that confidence in scientists has unexpected effects: respondents with high confidence in scientists feel less responsible for global warming, and also show less concern for global warming. These results have substantial implications for the interaction between scientists and the public in general, and for the public discussion of global warming and climate change in particular.

Paul M. Kellstedt; Sammy Zahran; Arnold Vedlitz

2008-01-01

172

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

USGS Publications Warehouse

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.

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

2013-01-01

173

A brief history of climate - the northern seas from the Last Glacial Maximum to global warming  

NASA Astrophysics Data System (ADS)

The understanding of climate and climate change is fundamentally concerned with two things: a well-defined and sufficiently complete climate record to be explained, for example of observed temperature, and a relevant mechanistic framework for making closed and consistent inferences concerning cause-and-effect. This is the case for understanding observed climate, as it is the case for historical climate as reconstructed from proxy data and future climate as projected by models. The present study offers a holistic description of northern maritime climate - from the Last Glacial Maximum through to the projected global warming of the 21st century - in this context. It includes the compilation of the most complete temperature record for Norway and the Norwegian Sea to date based on the synthesis of available terrestrial and marine paleoclimate reconstructions into continuous times series, and their continuation into modern and future climate with the instrumental record and a model projection. The scientific literature on a variable northern climate is reviewed against this background, and with a particular emphasis on the role of the Norwegian Atlantic Current - the Gulf Stream's extension towards the Arctic. This includes the introduction of an explicit and relatively simple diagnostic relation to quantify the change in ocean circulation consistent with reconstructed ocean temperatures. It is found that maritime climate and the strength of the Norwegian Atlantic Current are closely related throughout the record. The nature of the relation is however qualitatively different as one progresses from the past, through the present, and into the future.

Eldevik, Tor; Risebrobakken, Bjørg; Bjune, Anne E.; Andersson, Carin; Birks, H. John B.; Dokken, Trond M.; Drange, Helge; Glessmer, Mirjam S.; Li, Camille; Nilsen, Jan Even Ø.; Otterå, Odd Helge; Richter, Kristin; Skagseth, Øystein

2014-12-01

174

Interfacing Single Column Lake and Atmospheric Models: Application over Lake Geneva for Observed and Climate Warming Scenario  

NASA Astrophysics Data System (ADS)

A single-column atmospheric model has been coupled to a single-column lake model to simulate present-day as well as future lake temperature profiles following global climate warming conditions. Results of multi-year climate simulations are shown for the case of the deep station SHL2 (309 m) of Lake Geneva, Switzerland. The atmospheric model termed FIZL, is a column version of a limited-area model developed for regional climate modelling based on an off-line downscaling of GCM simulations. It is physically-based and it requires outputs from a previous GCM integration. The issues of local lake climate is addressed by combining precomputed atmospheric large-scale transports of momentum, heat, and moisture, called "the dynamics," and recomputed subgrid-scale parameterized effect (solar and infrared radiation fluxes, and latent and sensible heat fluxes), called "the physics," with the explicit numerical computations of the evolving lower boundary conditions provided by the lake model. The lake model, called k-epsilon (k-e), combines a buoyancy-extended k-e model with a seiche excitation and damping model to predict the diffusivity below the surface mixed layer. In this model, the vertical turbulent diffusivities are determined from the turbulent kinetic energy and energy dissipation. Details of the atmospheric-lake interface module, and a sensitivity analysis of the simulated thermal profiles to this coupler parameters are presented. Finally statistics of the change in the lake thermal profiles is also shown for the case of an equilibrium 2xCO2 global climate warming scenario.

Goyette, S.; Perroud, M.

2008-12-01

175

Understanding the Spatial Patterns of Global Warming and Climate Feedbacks with a New Analysis Approach  

NASA Astrophysics Data System (ADS)

Global warming due to a doubling of the atmospheric CO2 concentration has been studied extensively in terms of climate sensitivity to external forcing and feedbacks. While these studies provide new insights into the feedbacks of clouds, water vapor, atmospheric lapse rate, etc. they cannot answer how much of the net warming is due to a particular feedback agent such as cloud feedback. Recently a new analysis approach was suggested by Lu and Cai (2009). Instead of analyzing the climate sensitivity, they estimated the temperature changes due to individual feedback processes, whose sum gives the net warming as a result of external forcing and all feedback processes. They demonstrated the feasibility of this approach using an idealized model. In this study, we use a slab ocean model version of the NCAR Community Climate System Model version 3 (CCSM3) with full model physics to evaluate this approach and examine the spatial pattern of global warming in response to a doubling in atmospheric CO2. We will show the net temperature changes from 1xCO2 to 2xCO2 and their decomposition into contributions from radiative (water vapor, clouds, albedo, etc.) and non-radiative (convection, cloud condensation, dynamic transport, etc.) processes.

Song, X.; Zhang, G. J.; Cai, M.

2011-12-01

176

McMurdo Dry Valleys Climate Response to Plio-Pleistocene Warm Interglacial Climate Forcing  

NASA Astrophysics Data System (ADS)

The Antarctic Drilling Program recovered high quality Neogene sediment cores off of the coast of Ross Island recording a series of ice-contact, ice-proximal, ice-distal and marine facies suggesting grounding line migration along the sea floor. Chronology control of the core places glacial variability consistent with ~41 kyr orbital forcing. The marine facies suggests episodes of open-water conditions and elevated sea-surface temperatures in McMurdo Sound and the Ross Sea during the Pliocene. Recent Antarctic ice sheet modeling efforts have supported episodic retreat of the sea ice and possibly a frequent collapse of the West Antarctic Ice Sheet (WAIS) during the warmest intervals of the Pliocene-Pleistocene. Such repeated reduction in the Antarctic Ice Sheets occurs at a time when terrestrial records from near-by McMurdo Dry Valleys call for enduring hyper-arid cold desert conditions since the mid-to early Miocene. To assess whether hyper-arid cold desert climate could exist at high elevations within the McMurdo Dry Valleys during episodes of a diminished ice sheet (and near-by open water conditions), or if in fact these conditions are mutually exclusive, we simulated both present day (for validation) and paleo-climate conditions for Antarctic using a high resolution Regional Climate Model (RegCM3) nested within a medium resolution Global Climate Model (GCM) to predict paleo-climate as a function of ice sheet variability. RegCM3 simulations for paleo-conditions focused on the response of the Ross Sea sector to 1) orbital changes consistent with peak austral summer warmth, 2) reduction of ice shelves including the loss of the Ross and Filchner-Ronne Ice Shelves, 3) higher than modern carbon dioxide concentrations (400 - 800 ppmv) and 4) a highly diminished WAIS as predicted by the ice-sheet model. Results show mean atmospheric temperatures in the McMurdo Dry Valleys are most sensitive to loss of sea ice in McMurdo Sound / Ross Sea. If we assume a loss of marine grounded ice and remove the Antarctic ice shelves the mean atmospheric temperatures in the McMurdo Dry Valleys increases; model results suggest temperatures were 2.78°C and 2.38°C warmer than today at the coast and inland respectively although the rise in atmospheric temperatures during the summer months is typically of a smaller magnitude compared to the temperature rise predicted for the winter months. As expected the model showed warmer mean atmospheric temperatures with elevated levels of CO2. Precipitation also increased in the McMurdo Dry Valleys with increasing values of CO2. Initial model results for simulations run with a diminished WAIS predict increased atmospheric temperatures for most of the continent; temperature increase within the Transantarctic Mountains and McMurdo Dry Valleys is below the mean rise in Antarctic temperature for this simulation.

Kowalewski, D. E.; Deconto, R.; Seth, A.; Pollard, D.

2010-12-01

177

Abrupt climate change in West Antarctica and Greenland during the last deglacial warming  

NASA Astrophysics Data System (ADS)

The WAIS Divide ice core is the first Southern Hemisphere record with precision similar to ice cores from Greenland. The annually resolved timescale and small gas-age ice-age difference allow the phasing of climate change in the two hemispheres to be compared with unprecedented precision. We focus on the three abrupt climate changes in Greenland during the deglacial transition and the corresponding changes at WAIS Divide. The onset of the Antarctic Cold Reversal (ACR) is clearly defined in the WAIS Divide record and lagged the Bolling-Allerod (BA) warming by 150×50 years. The phasing of the other two abrupt climate changes cannot be distinguished from synchronous with an uncertainty of ~200 years because the transitions from warming to cooling (or cooling to warming) are not distinct in the WAIS Divide record. The lead-lag relationships of no more than a couple centuries confirm the tight coupling between hemispheres during the deglaciation. The independent timescale of WAIS Divide confirms that meltwater Pulse 1a began near-coincident with the BA and ACR although the lack of direct synchronization between the annually dated ice-core imescales and the radiometrically dated coral timescale prevents the phasing from being known to better than a couple of centuries. A new observation from WAIS Divide is that accumulation increased ~40% between 12.0 and 11.6 ka, with the accumulation increase ending approximately coincident with the warming at the end of the Younger Dryas in Greenland. Other Antarctic ice cores lack timescales with sufficient resolution to identify such abrupt changes so it is unclear how much of Antarctica was affected by the increased accumulation rates. The inter-hemispheric relationships are often limited to a discussion of warming, but the WAIS Divide records suggests that the moisture transport may be another important constraint on the mechanisms that drive abrupt climate change.

Fudge, T. J.; Steig, E. J.; Brook, E.; Buizert, C.; Conway, H.; Ding, Q.; Markle, B. R.; McConnell, J. R.; Pedro, J. B.; Schoenemann, S. W.; Severinghaus, J. P.; Sigl, M.; Sowers, T. A.; Taylor, K.; Waddington, E. D.

2013-12-01

178

Climate Warming and 21st-Century Drought in Southwestern North America  

NASA Astrophysics Data System (ADS)

Since 2000, southwestern North America has experienced widespread drought. Lakes Powell and Mead are now at less than 50% of their reservoir capacity, and drought or fire-related states of emergency were declared this past summer by governors in six western states. As with other prolonged droughts, such as the Dust Bowl during the 1930s, aridity has at times extended from northern Mexico to the southern Canadian prairies. A synthesis of climatological and paleoclimatological studies suggests that a transition to a more arid climate may be occurring due to global warming, with the prospect of sustained droughts being exacerbated by the potential reaction of the Pacific Ocean to warming.

MacDonald, Glen M.; Stahle, David W.; Diaz, Jose Villanueva; Beer, Nicholas; Busby, Simon J.; Cerano-Paredes, Julian; Cole, Julie E.; Cook, Edward R.; Endfield, Georgina; Gutierrez-Garcia, Genaro; Hall, Beth; Magana, Victor; Meko, David M.; Méndez-Pérez, Matias; Sauchyn, David J.; Watson, Emma; Woodhouse, Connie A.

2008-02-01

179

Possible climate warming effects on vegetation, forests, biotic (insect, pathogene) disturbances and agriculture in Central Siberia for 1960- 2050  

NASA Astrophysics Data System (ADS)

Regional Siberian studies have already registered climate warming over the last half a century (1960-2010). Our analysis showed that winters are already 2-3°C warmer in the north and 1-2°C warmer in the south by 2010. Summer temperatures increased by 1°C in the north and by 1-2°C in the south. Change in precipitation is more complicated, increasing on average 10% in middle latitudes and decreasing 10-20% in the south, promoting local drying in already dry landscapes. Our goal was to summarize results of research we have done for the last decade in the context of climate warming and its consequences for biosystems in Central Siberia. We modeled climate change effects on vegetation shifts, on forest composition and agriculture change, on the insect Siberian moth (Dendrolimus suprans sibiricus Tschetv) and pathogene (Lophodermium pinastri Chev) ranges in Central Siberia for a century (1960-2050) based on historical climate data and GCM-predicted data. Principal results are: In the warmer and drier climate projected by these scenarios, Siberian forests are predicted to decrease and shift northwards and forest-steppe and steppe ecosystems are predicted to dominate over 50% of central Siberia due to the dryer climate by 2080. Permafrost is not predicted to thaw deep enough to sustain dark (Pinus sibirica, Abies sibirica, and Picea obovata) taiga. Over eastern Siberia, larch (Larix dahurica) taiga is predicted to continue to be the dominant zonobiome because of its ability to withstand continuous permafrost. The model also predicts new temperate broadleaf forest and forest-steppe habitats; At least half of central Siberia is predicted to be climatically suitable for agriculture at the end of the century although potential croplands would be limited by the availability of suitable soils agriculture in central Siberia would likely benefit from climate warming Crop production may twofold increase as climate warms during the century; traditional crops (grain, potato, maize for silage) could be gradually shifted as far as 500 km from the south northwards (about 50-70 km per decade) and new crops (maize for grain, apricot, grape, gourds) may be introduced in the very south depending on winter conditions and would necessitate irrigation in a drier 2080 climate; The environment for the Siberian moth may considerably shrink in the future leaving suitable habitats only in highlands of mountains and the north of Eurasia. The moth habitats also depend on migration rates of tree species Larix spp., Abies sibirica, and Pinus sibirica being main food resources. Siberian moth may not be considered as a threat in climates with mild winter because larvae require continuos continental type winters. Needle-cast of Pinus sylvestris caused by Lophodermium pinastri Chev. was found to be strongly related to precipation including snow depth. In a predicted dryer climate, it would shift northwards followed sufficient water.

Tchebakova, N. M.; Parfenova, E. I.; Soja, A. J.; Lysanova, G. I.; Baranchikov, Y. N.; Kuzmina, N. A.

2012-04-01

180

Potential malaria outbreak in Germany due to climate warming: risk modelling based on temperature measurements and regional climate models  

Microsoft Academic Search

Purpose  Climate warming can change the geographic distribution and intensity of the transmission of vector-borne diseases such as\\u000a malaria. The transmitted parasites usually benefit from increased temperatures as both their reproduction and development\\u000a are accelerated. Lower Saxony (northwestern Germany) has been a malaria region until the 1950s, and the vector species are\\u000a still present throughout Germany. This gave reason to investigate

Marcel Holy; Gunther Schmidt; Winfried Schröder

2011-01-01

181

Changes in plant community composition lag behind climate warming in lowland forests.  

PubMed

Climate change is driving latitudinal and altitudinal shifts in species distribution worldwide, leading to novel species assemblages. Lags between these biotic responses and contemporary climate changes have been reported for plants and animals. Theoretically, the magnitude of these lags should be greatest in lowland areas, where the velocity of climate change is expected to be much greater than that in highland areas. We compared temperature trends to temperatures reconstructed from plant assemblages (observed in 76,634 surveys) over a 44-year period in France (1965-2008). Here we report that forest plant communities had responded to 0.54 °C of the effective increase of 1.07 °C in highland areas (500-2,600 m above sea level), while they had responded to only 0.02 °C of the 1.11 °C warming trend in lowland areas. There was a larger temperature lag (by 3.1 times) between the climate and plant community composition in lowland forests than in highland forests. The explanation of such disparity lies in the following properties of lowland, as compared to highland, forests: the higher proportion of species with greater ability for local persistence as the climate warms, the reduced opportunity for short-distance escapes, and the greater habitat fragmentation. Although mountains are currently considered to be among the ecosystems most threatened by climate change (owing to mountaintop extinction), the current inertia of plant communities in lowland forests should also be noted, as it could lead to lowland biotic attrition. PMID:22012261

Bertrand, Romain; Lenoir, Jonathan; Piedallu, Christian; Riofrío-Dillon, Gabriela; de Ruffray, Patrice; Vidal, Claude; Pierrat, Jean-Claude; Gégout, Jean-Claude

2011-11-24

182

Potential Impacts of Climate Warming on Water Supply Reliability in the Tuolumne and Merced River Basins, California  

PubMed Central

We present an integrated hydrology/water operations simulation model of the Tuolumne and Merced River Basins, California, using the Water Evaluation and Planning (WEAP) platform. The model represents hydrology as well as water operations, which together influence water supplied for agricultural, urban, and environmental uses. The model is developed for impacts assessment using scenarios for climate change and other drivers of water system behavior. In this paper, we describe the model structure, its representation of historical streamflow, agricultural and urban water demands, and water operations. We describe projected impacts of climate change on hydrology and water supply to the major irrigation districts in the area, using uniform 2°C, 4°C, and 6°C increases applied to climate inputs from the calibration period. Consistent with other studies, we find that the timing of hydrology shifts earlier in the water year in response to temperature warming (5–21 days). The integrated agricultural model responds with increased water demands 2°C (1.4–2.0%), 4°C (2.8–3.9%), and 6°C (4.2–5.8%). In this sensitivity analysis, the combination of altered hydrology and increased demands results in decreased reliability of surface water supplied for agricultural purposes, with modeled quantity-based reliability metrics decreasing from a range of 0.84–0.90 under historical conditions to 0.75–0.79 under 6°C warming scenario. PMID:24465455

Kiparsky, Michael; Joyce, Brian; Purkey, David; Young, Charles

2014-01-01

183

Long-term effects of warming and ocean acidification are modified by seasonal variation in species responses and environmental conditions  

PubMed Central

Warming of sea surface temperatures and alteration of ocean chemistry associated with anthropogenic increases in atmospheric carbon dioxide will have profound consequences for a broad range of species, but the potential for seasonal variation to modify species and ecosystem responses to these stressors has received little attention. Here, using the longest experiment to date (542 days), we investigate how the interactive effects of warming and ocean acidification affect the growth, behaviour and associated levels of ecosystem functioning (nutrient release) for a functionally important non-calcifying intertidal polychaete (Alitta virens) under seasonally changing conditions. We find that the effects of warming, ocean acidification and their interactions are not detectable in the short term, but manifest over time through changes in growth, bioturbation and bioirrigation behaviour that, in turn, affect nutrient generation. These changes are intimately linked to species responses to seasonal variations in environmental conditions (temperature and photoperiod) that, depending upon timing, can either exacerbate or buffer the long-term directional effects of climatic forcing. Taken together, our observations caution against over emphasizing the conclusions from short-term experiments and highlight the necessity to consider the temporal expression of complex system dynamics established over appropriate timescales when forecasting the likely ecological consequences of climatic forcing. PMID:23980249

Godbold, Jasmin A.; Solan, Martin

2013-01-01

184

The influence of Greenland melt water on climate during past and future warm periods: a model study  

NASA Astrophysics Data System (ADS)

"Can past climates teach us something about the future?" Under this general question of interest to most palaeoclimate-modeller we specified it more to "Can past changes in the strength of the Atlantic Meridional Overturning Circulation (AMOC) related to melt water from the Greenland Ice Sheet (GIS) teach us something about future changes in the AMOC forced by predicted partial melting of the GIS?" To address this question, we developed a series of sensitivity experiments with the global atmosphere-ocean-sea-ice model LOVECLIM to better understand the relationship between the strength of the Atlantic Meridional Overturning Circulation (AMOC) and Greenland Ice Sheet (GIS) melt over the last and present interglacials (the Eemian and the Holocene, respectively) and put these into perspective of future greenhouse gas emission scenarios. In terms of radiative forcing, future emission scenarios are different from past orbitally-forced warm periods, as past insolation varied per season and per latitude, whereas radiative forcing due to future greenhouse gas emissions has no seasonal component (i.e. it is an annual forcing) and shows little variation per latitude. However, the two can be compared when we consider the radiative forcing regimes of the different considered warm climates, by focusing on the energy that is potentially available from radiative forcing to melt the GIS. In a similar approach, Swingedouw et al. (2009) have shown in simulations with an AOGCM that the AMOC sensitivity relates non-linear to freshwater input and that under Last Glacial Maximum (LGM) conditions the climate is more sensitive compared to warmer climates. They conclude that different climatic conditions share similar patterns in response and that past climates are useful for models to evaluate their abilities in reproducing past events. The authors encourage further model sensitivity testing to gain a better understanding of this highly important question. In order to test this approach we performed a series of experiments in which we applied different versions of our model that differ in the sensitivity to freshwater forcing. These experiments cover all three periods considered: the Eemian, the Holocene and the 21st Century. We used different amounts of GIS melt fluxes that correspond to a wide range of changes in percent from modern-day ice sheet volume, ranging from as little as 5% to 100%. The GIS extent and topography was kept at present-day conditions. The future greenhouse gas emissions are taken from the Representative Concentration Pathways (Meinshausen et al. 2011), the new scenarios for climate change research. Our first results suggest that the warmer Eemian and the less warm Holocene test cases have a quite linear relationship in terms of AMOC sensitivity to GIS melt. In all our sensitivity experiments the Eemian is more sensitive to freshwater forcing than the Holocene. Meinshausen, M.; Smith, S.; Calvin, K.; Daniel, J.; Kainuma, M.; Lamarque, J.-F.; Matsumoto, K.; Montzka, S.; Raper, S.; Riahi, K.; Thomson, A.; Velders, G. & van Vuuren, D.,The RCP greenhouse gas concentrations and their extensions from 1765 to 2300, Climatic Change, Springer Netherlands, 2011, 109, 213-241 Swingedouw, D.; Mignot, J.; Braconnot, P.; Mosquet, E.; Kageyama, M. & Alkama, R.,Impact of Freshwater Release in the North Atlantic under Different Climate Conditions in an OAGCM, J. Climate, Journal of Climate, American Meteorological Society, 2009, 22, 6377-6403

Blaschek, Michael; Bakker, Pepijn; Renssen, Hans

2013-04-01

185

Indian Ocean warming during 1958-2004 simulated by a climate system model and its mechanism  

NASA Astrophysics Data System (ADS)

The mechanism responsible for Indian Ocean Sea surface temperature (SST) basin-wide warming trend during 1958-2004 is studied based on both observational data analysis and numerical experiments with a climate system model FGOALS-gl. To quantitatively estimate the relative contributions of external forcing (anthropogenic and natural forcing) and internal variability, three sets of numerical experiments are conducted, viz. an all forcing run forced by both anthropogenic forcing (greenhouse gases and sulfate aerosols) and natural forcing (solar constant and volcanic aerosols), a natural forcing run driven by only natural forcing, and a pre-industrial control run. The model results are compared to the observations. The results show that the observed warming trend during 1958-2004 (0.5 K (47-year)-1) is largely attributed to the external forcing (more than 90 % of the total trend), while the residual is attributed to the internal variability. Model results indicate that the anthropogenic forcing accounts for approximately 98.8 % contribution of the external forcing trend. Heat budget analysis shows that the surface latent heat flux due to atmosphere and surface longwave radiation, which are mainly associated with anthropogenic forcing, are in favor of the basin-wide warming trend. The basin-wide warming is not spatially uniform, but with an equatorial IOD-like pattern in climate model. The atmospheric processes, oceanic processes and climatological latent heat flux together form an equatorial IOD-like warming pattern, and the oceanic process is the most important in forming the zonal dipole pattern. Both the anthropogenic forcing and natural forcing result in easterly wind anomalies over the equator, which reduce the wind speed, thereby lead to less evaporation and warmer SST in the equatorial western basin. Based on Bjerknes feedback, the easterly wind anomalies uplift the thermocline, which is unfavorable to SST warming in the eastern basin, and contribute to SST warming via deeper thermocline in the western basin. The easterly anomalies also drive westward anomalous equatorial currents, against the eastward climatology currents, which is in favor of the SST warming in the western basin via anomalous warm advection. Therefore, both the atmospheric and oceanic processes are in favor of the IOD-like warming pattern formation over the equator.

Dong, Lu; Zhou, Tianjun; Wu, Bo

2014-01-01

186

Mapping climate conditions with materials corrosion  

NASA Astrophysics Data System (ADS)

The world's first comprehensive materials corrosion mapping system can predict the effects that climatic conditions have on the life cycle of products ranging from automobiles to bridges, according to Australia's Commonwealth Scientific and Industrial Research Organisation (CSIRO) and the Australian Industrial Galvanizers Corporation. Both jointly announced the system on 14 November.The mapping system, which incorporates conditions such as moisture, salinity pollution, and prevailing winds, can predict the corrosion of materials in any part of Australia, they said. Ivan Cole of CSIRO Materials Engineering said the mapping system even takes into account durability factors impacting on greenhouse gas contributions and soil conditions, making it a unique tool for Australian industry.

Showstack, Randy

187

Climate warming could reduce runoff significantly in New England, USA  

USGS Publications Warehouse

The relation between mean annual temperature (MAT), mean annual precipitation (MAP) and evapotranspiration (ET) for 38 forested watersheds was determined to evaluate the potential increase in ET and resulting decrease in stream runoff that could occur following climate change and lengthening of the growing season. The watersheds were all predominantly forested and were located in eastern North America, along a gradient in MAT from 3.5??C in New Brunswick, CA, to 19.8??C in northern Florida. Regression analysis for MAT versus ET indicated that along this gradient ET increased at a rate of 2.85 cm??C-1 increase in MAT (??0.96 cm??C-1, 95% confidence limits). General circulation models (GCM) using current mid-range emission scenarios project global MAT to increase by about 3??C during the 21st century. The inferred, potential, reduction in annual runoff associated with a 3??C increase in MAT for a representative small coastal basin and an inland mountainous basin in New England would be 11-13%. Percentage reductions in average daily runoff could be substantially larger during the months of lowest flows (July-September). The largest absolute reductions in runoff are likely to be during April and May with smaller reduction in the fall. This seasonal pattern of reduction in runoff is consistent with lengthening of the growing season and an increase in the ratio of rain to snow. Future increases in water use efficiency (WUE), precipitation, and cloudiness could mitigate part or all of this reduction in runoff but the full effects of changing climate on WUE remain quite uncertain as do future trends in precipitation and cloudiness.

Huntington, T.G.

2003-01-01

188

Impact of CO2Induced Warming on Simulated Hurricane Intensity and Precipitation: Sensitivity to the Choice of Climate Model and Convective Parameterization  

Microsoft Academic Search

Previous studies have found that idealized hurricanes, simulated under warmer, high-CO 2 conditions, are more intense and have higher precipitation rates than under present-day conditions. The present study explores the sensitivity of this result to the choice of climate model used to define the CO2-warmed environment and to the choice of convective parameterization used in the nested regional model that

Thomas R. Knutson; Robert E. Tuleya

2004-01-01

189

Spatiotemporal change in geographical distribution of global climate types in the context of climate warming  

NASA Astrophysics Data System (ADS)

After standardizing global land climate gridded data from the Climatic Research Unit TS (time-series) 3.1 dataset for the period 1901-2009, cluster analysis is used to objectively classify world climates into 14 climate types. These climate types establish a baseline classification map and the types are named according to Köppen-Geiger climate classifications. Although the cluster analysis and Köppen classification methods are very different, the distributions of climate types obtained by the two methods are similar. Moreover, the climate types we identify also coincide well with their corresponding vegetation types. Thus, cluster analysis can be used as an effective alternative to the Köppen classification method for classifying world climate types. The spatial and temporal changes in geographical distribution of global climate types were investigated in 25-year intervals, and Cohen's kappa coefficient is used to detect agreement between the periods. Globally, although an obvious trend in increasing global temperature is found, distribution of climate types overall show no distinct changes over the periods. However, at the regional scale, spatial change in distribution of climate types is evident in South America and Africa. In South America, larger areas of the "fully humid equatorial rainforest" (Af) and "equatorial savannah with dry winter" (Aw) climate types have changed types. In Africa, changes mainly occurred in the Af, "equatorial savannah with dry summer" (As), Aw, "steppe climate" (BS), and "desert climate" (BW) climate types. Moreover, some climate types, including Af, "equatorial monsoon" (Am), BS, BW, and "tundra climate" (ET), were susceptible to temporal climate changes, especially in the period 1976-2009.

Zhang, Xianliang; Yan, Xiaodong

2014-08-01

190

Hamburg 2K: Climate modeling and downscaling for Hamburg, Germany under a 2 K global warming scenario  

NASA Astrophysics Data System (ADS)

The European Union has established a 2 K warming of average annual global surface temperature above pre-industrial levels as a target to avoid disruptive climate change. The Hamburg 2K project seeks to model the climate of Hamburg, Germany subject to this target warming by the end of the 21st century. A general circulation model (ECHAM5) with a greenhouse gas scenario consistent with this target (E1) provides a source for dynamical and statistical-dynamical model downscaling at the regional scale, using the Regional Model (REMO), and at the mesoscale, using the Mesoscale Transport and fluid (Stream) Model (METRAS). Regional scale model estimates provide forcing for off-line modeling of the North Sea circulation with the Hamburg Shelf-Ocean Model (HAMSOM). This presentation concentrates on the urban climate component of the 2K scenario. The approach quantifies the projected change in both the meteorology and the urban development. The modeling strategy allows for a discrete diagnosis of each contribution. For the meteorology, the project identifies an urban climate change signal between the late 20th and late 21st centuries using a statistical-dynamical downscaling technique. Cluster analysis of multiple REMO realizations generates a series of archetypical synoptic conditions, a.k.a., weather types. The frequency change of these weather types between present and future climate yields a climate change signal. The potential for distinctively new weather types in the future climate is also investigated. Regional weather types provide the forcing for simulations with METRAS at 1 km resolution. These simulations provide further assessment of urban climate change at a scale more sensitive to the heterogeneous urban surface. Some initial METRAS modeling results will be presented here. For the urban development, the METRAS model simulations benefit from a detailed surface cover map including over 50 classes of natural and artificial surfaces tailored specifically for Hamburg. The simulations of future climate incorporate estimates of future surface cover. Evaluation of current municipal construction plans helps quantify trends in building density and change in unsealed surface cover. An off-line urban planning model tuned for the 2K scenario incorporates these plans into its parameterizations and assists in deriving a future surface cover map of Hamburg.

Flagg, D. D.; Grawe, D.; Daneke, C.; Hoffmann, P.; Jacob, D.; Kirschner, P.; Kriegsmann, A.; Linde, M.; Mayer, B.; O'Driscoll, K. T.; Pohlmann, T.; Schlünzen, K. H.; Schoetter, R.; Teichert, W.; Zorita, E.

2011-12-01

191

Impact of a global warming on biospheric sources of methane and its climatic consequences  

NASA Technical Reports Server (NTRS)

Most of atmospheric methane originates by bacterial processes in anaerobic environments within the soil which are found to become more productive with increases in ambient temperature. A warming of climate, due to increasing levels of industrial gases resulting from fossil fuel burning, is thus likely to increase methane abundance within the atmosphere. This may lead to further heating of the atmosphere, since both methane and ozone (which is generated in the troposphere from reactions of methane) have greenhouse effects. This feedback mechanism has been explored with the use of a coupled climate-chemical model of the troposphere, by the calculation of the impact of the predicted global warming due to increased emissions of carbon dioxide and other industrial gases on the biospheric sources of methane.

Hameed, S.; Cess, R. D.

1980-01-01

192

Climate change, global warming and coral reefs: modelling the effects of temperature.  

PubMed

Climate change and global warming have severe consequences for the survival of scleractinian (reef-building) corals and their associated ecosystems. This review summarizes recent literature on the influence of temperature on coral growth, coral bleaching, and modelling the effects of high temperature on corals. Satellite-based sea surface temperature (SST) and coral bleaching information available on the internet is an important tool in monitoring and modelling coral responses to temperature. Within the narrow temperature range for coral growth, corals can respond to rate of temperature change as well as to temperature per se. We need to continue to develop models of how non-steady-state processes such as global warming and climate change will affect coral reefs. PMID:18565794

Crabbe, M James C

2008-10-01

193

Response of the Arabian Sea to global warming and associated regional climate shift.  

PubMed

The response of the Arabian Sea to global warming is the disruption in the natural decadal cycle in the sea surface temperature (SST) after 1995, followed by a secular warming. The Arabian Sea is experiencing a regional climate-shift after 1995, which is accompanied by a five fold increase in the occurrence of "most intense cyclones". Signatures of this climate-shift are also perceptible over the adjacent landmass of India as: (1) progressively warmer winters, and (2) decreased decadal monsoon rainfall. The warmer winters are associated with a 16-fold decrease in the decadal wheat production after 1995, while the decreased decadal rainfall was accompanied by a decline of vegetation cover and increased occurrence of heat spells. We propose that in addition to the oceanic thermal inertia, the upwelling-driven cooling provided a mechanism that offset the CO(2)-driven SST increase in the Arabian Sea until 1995. PMID:19592084

Kumar, S Prasanna; Roshin, Raj P; Narvekar, Jayu; Kumar, P K Dinesh; Vivekanandan, E

2009-12-01

194

Warm-water decapods and the trophic amplification of climate in the North Sea  

PubMed Central

A long-term time series of plankton and benthic records in the North Sea indicates an increase in decapods and a decline in their prey species that include bivalves and flatfish recruits. Here, we show that in the southern North Sea the proportion of decapods to bivalves doubled following a temperature-driven, abrupt ecosystem shift during the 1980s. Analysis of decapod larvae in the plankton reveals a greater presence and spatial extent of warm-water species where the increase in decapods is greatest. These changes paralleled the arrival of new species such as the warm-water swimming crab Polybius henslowii now found in the southern North Sea. We suggest that climate-induced changes among North Sea decapods have played an important role in the trophic amplification of a climate signal and in the development of the new North Sea dynamic regime. PMID:20554562

Lindley, J. A.; Beaugrand, G.; Luczak, C.; Dewarumez, J.-M.; Kirby, R. R.

2010-01-01

195

Enhanced Climatic Warming in the Tibetan Plateau Due to Double CO2: A Model Study  

NASA Technical Reports Server (NTRS)

The NCAR (National Center for Atmospheric Research) regional climate model (RegCM2) with time-dependent lateral meteorological fields provided by a 130-year transient increasing CO2 simulation of the NCAR Climate System Model (CSM) has been used to investigate the mechanism of enhanced ground temperature warming over the TP (Tibetan Plateau). From our model results, a remarkable tendency of warming increasing with elevation is found for the winter season, and elevation dependency of warming is not clearly recognized in the summer season. This simulated feature of elevation dependency of ground temperature is consistent with observations. Based on an analysis of surface energy budget, the short wave solar radiation absorbed at the surface plus downward long wave flux reaching the surface shows a strong elevation dependency, and is mostly responsible for enhanced surface warming over the TP. At lower elevations, the precipitation forced by topography is enhanced due to an increase in water vapor supply resulted from a warming in the atmosphere induced by doubling CO2. This precipitation enhancement must be associated with an increase in clouds, which results in a decline in solar flux reaching surface. At higher elevations, large snow depletion is detected in the 2xCO2run. It leads to a decrease in albedo, therefore more solar flux is absorbed at the surface. On the other hand, much more uniform increase in downward long wave flux reaching the surface is found. The combination of these effects (i.e. decrease in solar flux at lower elevations, increase in solar flux at higher elevation and more uniform increase in downward long wave flux) results in elevation dependency of enhanced ground temperature warming over the TP.

Chen, Baode; Chao, Winston C.; Liu, Xiao-Dong; Lau, William K. M. (Technical Monitor)

2001-01-01

196

The ice-core record - Climate sensitivity and future greenhouse warming  

NASA Technical Reports Server (NTRS)

The prediction of future greenhouse-gas-warming depends critically on the sensitivity of earth's climate to increasing atmospheric concentrations of these gases. Data from cores drilled in polar ice sheets show a remarkable correlation between past glacial-interglacial temperature changes and the inferred atmospheric concentration of gases such as carbon dioxide and methane. These and other palaeoclimate data are used to assess the role of greenhouse gases in explaining past global climate change, and the validity of models predicting the effect of increasing concentrations of such gases in the atmosphere.

Lorius, C.; Raynaud, D.; Jouzel, J.; Hansen, J.; Le Treut, H.

1990-01-01

197

Floodplains, permafrost, cottonwood trees, and peat: What happened the last time climate warmed suddenly in arctic Alaska?  

NASA Astrophysics Data System (ADS)

We use the stratigraphy of floodplains on Alaska's North Slope to describe how tundra watersheds responded to climate changes over the last 15,000 calibrated years BP (15 cal ka BP). Two episodes of extremely rapid floodplain alluviation occurred during the Pleistocene-Holocene transition, one between 14 and 12.8 cal ka BP and the other between 11.5 and 9.5 cal ka BP. These aggradation episodes coincided with periods of warming in summer when cottonwood ( Populus balsamifera L.) expanded its range, peatlands became established, and widespread thermokarst occurred. The two aggradation episodes were separated by a period of floodplain incision during the Younger Dryas under cooler and possibly drier conditions. At times of increasing summer warmth, melting permafrost and enhanced precipitation probably triggered widespread mass wasting on hillslopes that overwhelmed the capacity of streams to transport sediment downstream, and rapid floodplain aggradation resulted. After peatlands became widespread in the early Holocene, rivers slowly incised their valley fills. Because major pulses of sediment input were limited to times of rapid thaw and increasing moisture, many floodplains on the North Slope have been effectively decoupled from upstream hillslopes for much of the past 15,000 years. Our findings: (a) confirm the sensitivity of arctic watersheds to rapid warming in summer, (b) emphasize the importance of hillslope mass wasting in landscape-scale responses to climate change, and (c) suggest that the presence of peatland on this arctic landscape today has raised its geomorphic response threshold to climate warming compared to what it was 14,000 years ago.

Mann, Daniel H.; Groves, Pamela; Reanier, Richard E.; Kunz, Michael L.

2010-12-01

198

Long-Term Global Warming Scenarios Computed with an Efficient Coupled Climate Model  

Microsoft Academic Search

We present global warming scenarios computed with an intermediate-complexity atmosphere-ocean-sea ice model which has been extensively validated for a range of past climates (e.g., the Last Glacial Maximum). Our simulations extend to the year 3000, beyond the expected peak of CO2 concentrations. The thermohaline ocean circulation declines strongly in all our scenarios over the next 50 years due to a

Stefan Rahmstorf; Andrey Ganopolski

1999-01-01

199

Impacts of climate warming on lake fish community structure and potential effects on ecosystem function  

Microsoft Academic Search

Fish play a key role in the trophic dynamics of lakes, not least in shallow systems. With climate warming, complex changes\\u000a in fish community structure may be expected owing to the direct and indirect effects of temperature, and indirect effects\\u000a of eutrophication, water-level changes and salinisation on fish metabolism, biotic interactions and geographical distribution.\\u000a We review published and new data

Erik Jeppesen; Mariana Meerhoff; Kerstin Holmgren; Ivan González-Bergonzoni; Franco Teixeira-de Mello; Steven A. J. Declerck; Luc De Meester; Martin Søndergaard; Torben L. Lauridsen; Rikke Bjerring; José Maria Conde-Porcuna; Néstor Mazzeo; Carlos Iglesias; Maja Reizenstein; Hilmar J. Malmquist; Zhengwen Liu; David Balayla; Xavier Lazzaro

2010-01-01

200

Climate warming impact on degree-days and building energy demand in Switzerland  

Microsoft Academic Search

The impact of climate warming on Swiss building energy demand was investigated by means of the degree-days method. A procedure to estimate heating degree-days (HDD) and cooling degree-days (CDD) from monthly temperature data was developed, tested and applied to four representative Swiss locations. Past trends were determined from homogenized temperature data for the period 1901–2003. The range of possible future

M. Christenson; H. Manz; D. Gyalistras

2006-01-01

201

A warming climate may result in increased morbidity and mortality related to ozone, an  

E-print Network

- tion, and a variety of other health outcomes (Kinney 1999; Koken et al. 2003). A rela- tively recent a changing climate (Kinney et al., in press). Warming of 1.4­3.6°C (2.6­6.5°F) by the 2050s has been an integrated modeling system in the New York metropolitan region (Kinney et al., in press). The modeling system

202

Students’ conceptions about the greenhouse effect, global warming, and climate change  

Microsoft Academic Search

The purpose of this study was to investigate students’ conceptions of the greenhouse effect, global warming, and climate change.\\u000a The study was descriptive in nature and reflected a cross-age design involving the collection of qualitative data from 51\\u000a secondary students from three different schools in the Midwest, USA. These data were analyzed for content in an inductive\\u000a manner to identify

Daniel P. Shepardson; Dev Niyogi; Soyoung Choi; Umarporn Charusombat

2011-01-01

203

500-year climate cycles stacking of recent centennial warming documented in an East Asian pollen record  

NASA Astrophysics Data System (ADS)

Here we presented a high-resolution 5350-year pollen record from a maar annually laminated lake in East Asia (EA). Pollen record reflected the dynamics of vertical vegetation zones and temperature change. Spectral analysis on pollen percentages/concentrations of Pinus and Quercus, and a temperature proxy, revealed ~500-year quasi-periodic cold-warm fluctuations during the past 5350 years. This ~500-year cyclic climate change occurred in EA during the mid-late Holocene and even the last 150 years dominated by anthropogenic forcing. It was almost in phase with a ~500-year periodic change in solar activity and Greenland temperature change, suggesting that ~500-year small variations in solar output played a prominent role in the mid-late Holocene climate dynamics in EA, linked to high latitude climate system. Its last warm phase might terminate in the next several decades to enter another ~250-year cool phase, and thus this future centennial cyclic temperature minimum could partially slow down man-made global warming.

Xu, Deke; Lu, Houyuan; Chu, Guoqiang; Wu, Naiqin; Shen, Caiming; Wang, Can; Mao, Limi

2014-01-01

204

500-year climate cycles stacking of recent centennial warming documented in an East Asian pollen record.  

PubMed

Here we presented a high-resolution 5350-year pollen record from a maar annually laminated lake in East Asia (EA). Pollen record reflected the dynamics of vertical vegetation zones and temperature change. Spectral analysis on pollen percentages/concentrations of Pinus and Quercus, and a temperature proxy, revealed ~500-year quasi-periodic cold-warm fluctuations during the past 5350 years. This ~500-year cyclic climate change occurred in EA during the mid-late Holocene and even the last 150 years dominated by anthropogenic forcing. It was almost in phase with a ~500-year periodic change in solar activity and Greenland temperature change, suggesting that ~500-year small variations in solar output played a prominent role in the mid-late Holocene climate dynamics in EA, linked to high latitude climate system. Its last warm phase might terminate in the next several decades to enter another ~250-year cool phase, and thus this future centennial cyclic temperature minimum could partially slow down man-made global warming. PMID:24402348

Xu, Deke; Lu, Houyuan; Chu, Guoqiang; Wu, Naiqin; Shen, Caiming; Wang, Can; Mao, Limi

2014-01-01

205

500-year climate cycles stacking of recent centennial warming documented in an East Asian pollen record  

PubMed Central

Here we presented a high-resolution 5350-year pollen record from a maar annually laminated lake in East Asia (EA). Pollen record reflected the dynamics of vertical vegetation zones and temperature change. Spectral analysis on pollen percentages/concentrations of Pinus and Quercus, and a temperature proxy, revealed ~500-year quasi-periodic cold-warm fluctuations during the past 5350 years. This ~500-year cyclic climate change occurred in EA during the mid-late Holocene and even the last 150 years dominated by anthropogenic forcing. It was almost in phase with a ~500-year periodic change in solar activity and Greenland temperature change, suggesting that ~500-year small variations in solar output played a prominent role in the mid-late Holocene climate dynamics in EA, linked to high latitude climate system. Its last warm phase might terminate in the next several decades to enter another ~250-year cool phase, and thus this future centennial cyclic temperature minimum could partially slow down man-made global warming. PMID:24402348

Xu, Deke; Lu, Houyuan; Chu, Guoqiang; Wu, Naiqin; Shen, Caiming; Wang, Can; Mao, Limi

2014-01-01

206

Biophysical feedbacks between the Pleistocene megafauna extinction and climate: The first human-induced global warming?  

NASA Astrophysics Data System (ADS)

A large increase in Betula during a narrow 1000 year window, ˜13,800 years before present (YBP) in Alaska and Yukon corresponded in time with the extinction of mammoths and the arrival of humans. Pollen data indicate the increase in Betula during this time was widespread across Siberia and Beringia. We hypothesize that Betula increased due to a combination of a warming climate and reduced herbivory following the extinction of the Pleistocene mega herbivores. The rapid increase in Betula modified land surface albedo which climate-model simulations indicate would cause an average net warming of ˜0.021°C per percent increase in high latitude (53-73°N) Betula cover. We hypothesize that the extinction of mammoths increased Betula cover, which would have warmed Siberia and Beringia by on average 0.2°C, but regionally by up to 1°C. If humans were partially responsible for the extinction of the mammoths, then human influences on global climate predate the origin of agriculture.

Doughty, Christopher E.; Wolf, Adam; Field, Christopher B.

2010-08-01

207

Biophysical feedbacks between the Pleistocene megafauna extinction and climate: The first human induced global warming?  

NASA Astrophysics Data System (ADS)

A large increase in Betula during a narrow 1000 year window, ˜13,800 years before present (YBP) in Alaska and Yukon corresponded in time with the extinction of mammoths and the arrival of humans. Pollen data indicate the increase in Betula during this time was widespread across Siberia and Beringia. We hypothesize that Betula increased due to a combination of a warming climate and reduced herbivory following the extinction of the Pleistocene mega herbivores. The rapid increase in Betula modified land surface albedo which climate model simulations indicate would cause an average net warming of ˜0.021°C per percent increase in high latitude (53-73°N) Betula cover. We hypothesize that the extinction of mammoths increased Betula cover, which would have warmed Siberia and Beringia by on average 0.2°C, but regionally by up to 1°C. If humans were partially responsible for the extinction of the mammoths, then human influences on global climate predate the origin of agriculture.

Doughty, C.; Field, C.; Wolf, A.

2010-12-01

208

Global warming from chlorofluorocarbons and their alternatives: Time scales of chemistry and climate  

NASA Astrophysics Data System (ADS)

The halocarbons (chloroflurocarbons, CFCs, and their replacement chemicals: the hydrochloroflurocarbons, HCFCs, and the hydrofluorocarbons, HFCs) are greenhouse gases. The atmospheric accumulation of these gases is expected to add to the global warming predicted for expected increases of CO 2, CH 4, N 2O, tropospheric ozone and H 2O. Over the next decades, production of CFCs is scheduled to be phased out, while emissions of their alternatives are expected to increase. A simple model is used to illustrate the methodology for determining the time variations of the radiative forcing and temperature changes attributable to the direct greenhouse effect from potential emissions of the halocarbons. Although there are uncertainties associated with the lifetimes of the greenhouse gases, CFCs and their substitutes, the future growth rates of these gases, and the parameters used to simulate the response of the Earth-climate system, the method serves to illustrate an important aspect of the greenhouse warming issue beyond what is provided by the various greenhouse warming indices. Our results show that for likely substitution scenarios, the warming due to halocarbons will correspond to 4-10% of the total expected greenhouse warming at the year 2100. However, uncontrolled growth of the substitutes could result in an eight-fold increase in halocarbon production and a doubling of the halocarbon contribution by 2100.

Ko, Malcolm K. W.; Sze, Nien Dak; Molnar, Gyula; Prather, Michael J.

209

Combined effects of global warming and an Atlantic meridional overturning circulation shutdown on West African and European climate  

NASA Astrophysics Data System (ADS)

We investigate the effects of an Atlantic meridional overturning circulation (AMOC) shutdown, for example, due to an influx of fresh water from Arctic ice sheet melting, in combination with global warming (Intergovernmental Panel on Climate Change's A2 business as normal emissions scenario) on West African and European climate. Shutdown of the AMOC by the end of this century is generally seen as possible but not likely, but Arctic ice is melting more quickly than predicted by global models, and the consequences for climate may be severe and the changes abrupt. A regional climate model with 90-km grid spacing is used to conduct a series of present day and future AMOC shutdown simulations. The present-day control initial surface and lateral boundary conditions are derived from the present day National Center for Environmental Prediction reanalysis 2 (NCEP2). For the future runs we use coupled atmosphere-ocean GCM anomalies generated from the Intergovernmental Panel on Climate Change's Assessment Report 4 (IPCC AR4) A2 business as normal emission scenario experiment and apply them directly to the present day control boundary conditions. An idealized SSTA is derived and applied to the present day SSTs based upon coupled atmosphere/ocean GCM water hosing experiments that force a shutdown of the AMOC, but placed in the context of under global warming, In both the boreal spring and summer months, cooling in the eastern Atlantic due to the AMOC shutdown causes an eastward extension of the North Atlantic subtropical high over Europe and rainfall rates decrease markedly throughout most of Europe. In May and June, rainfall rates decrease by 50-80% over Sahelian Africa as a secondary response to the eastern Atlantic cool SSTs, as dry air is advected southward, associated with enhanced northerly flow. In contrast, the atmospheric response to the SSTA in the North Atlantic over Europe and West Africa is decoupled during the boreal summer months; rainfall over Europe continues to decrease by up to 90%, while precipitation over West Africa is largely attributable to the response of the African monsoon to the global warming signal in the Gulf of Guinea. Along the Guinean coast, rainfall rates actually increase by up to 10%, while over the western Sahel rainfall rates decrease by 40%.

Brown, M. G.; Vizy, E. K.; Cook, K. H.

2011-12-01

210

New proofs of the recent climate warming over the Tibetan Plateau as a result of the increasing greenhouse gases emissions  

Microsoft Academic Search

A striking climate warming over the Tibetan Plateau during the last decades has been revealed by many studies, but evidence\\u000a linking it to human activity is insufficient. By using historical observations, here we show that the in situ climate warming is accompanied by a distinct decreasing trend of the diurnal range of surface air temperature. The ERA40\\u000a reanalysis further indicates

Anmin Duan; Guoxiong Wu; Qiong Zhang; Yimin Liu

2006-01-01

211

Soil Warming Alters the Nitrogen Cycle: Ecosystem Implications and Feedbacks to the Climate System  

NASA Astrophysics Data System (ADS)

Increases in soil temperatures associated with global warming have the potential to accelerate nitrogen turnover in soils, which could alter other biogeochemical processes and eventually affect the structure of these forests. Over the past five years we have been studying soil and plant responses to soil warming in large plots in a deciduous stand at Harvard Forest in central Massachusetts. We have heated the soil 5°C above ambient and measured nitrogen cycling parameters including in situ net nitrogen mineralization and nitrification, nitrogen leaching and nitrous oxide (N2O) fluxes. We have also measured various aspects of the carbon cycle including soil respiration and carbon accumulation in vegetation. Over the first five years of the study, we observed a mean annual increase in the net nitrogen mineralized in the warmed plot of 23.8 kg N ha-1. While nitrification rates were low throughout the five years in the control plot, they increased in the warmed plot to account for over 25% of the total net nitrogen mineralized in year five. The increase in nitrogen mineralization stimulated tree growth and carbon storage in woody tissue in the warmed plot. The increased carbon storage in the trees compensated for more than half of the carbon lost from the soils due to accelerated decay of soil organic matter and so reduced the magnitude of the positive feedback to the climate system due to soil warming. We hypothesize that the increase in nitrification we observed will eventually "open" the nitrogen cycle and make gaseous and solution losses more likely. To date, however, we have measured no major losses of nitrous oxide or solution losses of nitrate in response to soil warming. Trees with the capacity to use nitrate may have a competitive advantage in a warmer world. Nitrate-using plants have an inducible enzyme that transforms nitrate to ammonium, a key building block for producing essential amino acids and proteins. Studies by our research group and by others have shown that red maples (Acer rubrum), when grown with high levels of nitrate, have a greater ability to produce this enzyme than many other species common to the region's forests. We have also observed that red maple seedlings and saplings show a higher growth response to soil warming than juvenile plants of other species. Our working hypothesis is that some of this response is linked to the capacity of red maple to use the nitrate produced in the warmed soils. In the long term, warming could lead to red maples becoming a more dominant tree in the forests of southern New England.

Butler, S. M.; Melillo, J. M.; Johnson, J. E.; Mohan, J. E.; Steudler, P. A.; Bowles, F. P.

2008-12-01

212

Change of ocean circulation in the East Asian Marginal Seas under different climate conditions  

NASA Astrophysics Data System (ADS)

Global climate models do not properly resolve an ocean environment in the East Asian Marginal Seas (EAMS), which is mainly due to a poor representation of the topography in continental shelf region and a coarse spatial resolution. To examine a possible change of ocean environment under global warming in the EAMS, therefore we used North Pacific Regional Ocean Model. The regional model was forced by atmospheric conditions extracted from the simulation results of the global climate models for the 21st century projected by the IPCC SRES A1B scenario as well as the 20th century. The North Pacific Regional Ocean model simulated a detailed pattern of temperature change in the EAMS showing locally different rising or falling trend under the future climate condition, while the global climate models simulated a simple pattern like an overall increase. Changes of circulation pattern in the EAMS such as an intrusion of warm water into the Yellow Sea as well as the Kuroshio were also well resolved. Annual variations in volume transports through the Taiwan Strait and the Korea Strait under the future condition were simulated to be different from those under present condition. Relative ratio of volume transport through the Soya Strait to the Tsugaru Strait also responded to the climate condition.

Min, Hong Sik; Kim, Cheol-Ho; Kim, Young Ho

2010-05-01

213

Heat-Related Mortality in a Warming Climate: Projections for 12 U.S. Cities  

PubMed Central

Heat is among the deadliest weather-related phenomena in the United States, and the number of heat-related deaths may increase under a changing climate, particularly in urban areas. Regional adaptation planning is unfortunately often limited by the lack of quantitative information on potential future health responses. This study presents an assessment of the future impacts of climate change on heat-related mortality in 12 cities using 16 global climate models, driven by two scenarios of greenhouse gas emissions. Although the magnitude of the projected heat effects was found to differ across time, cities, climate models and greenhouse pollution emissions scenarios, climate change was projected to result in increases in heat-related fatalities over time throughout the 21st century in all of the 12 cities included in this study. The increase was more substantial under the high emission pathway, highlighting the potential benefits to public health of reducing greenhouse gas emissions. Nearly 200,000 heat-related deaths are projected to occur in the 12 cities by the end of the century due to climate warming, over 22,000 of which could be avoided if we follow a low GHG emission pathway. The presented estimates can be of value to local decision makers and stakeholders interested in developing strategies to reduce these impacts and building climate change resilience. PMID:25365060

Petkova, Elisaveta P.; Bader, Daniel A.; Anderson, G. Brooke; Horton, Radley M.; Knowlton, Kim; Kinney, Patrick L.

2014-01-01

214

Warm climates of the past—a lesson for the future?  

PubMed Central

This Discussion Meeting Issue of the Philosophical Transactions A had its genesis in a Discussion Meeting of the Royal Society which took place on 10–11 October 2011. The Discussion Meeting, entitled ‘Warm climates of the past: a lesson for the future?’, brought together 16 eminent international speakers from the field of palaeoclimate, and was attended by over 280 scientists and members of the public. Many of the speakers have contributed to the papers compiled in this Discussion Meeting Issue. The papers summarize the talks at the meeting, and present further or related work. This Discussion Meeting Issue asks to what extent information gleaned from the study of past climates can aid our understanding of future climate change. Climate change is currently an issue at the forefront of environmental science, and also has important sociological and political implications. Most future predictions are carried out by complex numerical models; however, these models cannot be rigorously tested for scenarios outside of the modern, without making use of past climate data. Furthermore, past climate data can inform our understanding of how the Earth system operates, and can provide important contextual information related to environmental change. All past time periods can be useful in this context; here, we focus on past climates that were warmer than the modern climate, as these are likely to be the most similar to the future. This introductory paper is not meant as a comprehensive overview of all work in this field. Instead, it gives an introduction to the important issues therein, using the papers in this Discussion Meeting Issue, and other works from all the Discussion Meeting speakers, as exemplars of the various ways in which past climates can inform projections of future climate. Furthermore, we present new work that uses a palaeo constraint to quantitatively inform projections of future equilibrium ice sheet change. PMID:24043873

Lunt, D. J.; Elderfield, H.; Pancost, R.; Ridgwell, A.; Foster, G. L.; Haywood, A.; Kiehl, J.; Sagoo, N.; Shields, C.; Stone, E. J.; Valdes, P.

2013-01-01

215

Responses of the leading mode of coldwave intensity in China to a warming climate  

NASA Astrophysics Data System (ADS)

Regional extreme cold events have changed notably with recent global warming. Understanding how these cold extremes change in China is an urgent issue. This study examines the responses of the dominant mode of China coldwave intensity (CWI) to global warming by comparing observations with simulations from the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4). The leading modes of the CWI derived from empirical orthogonal function (EOF) analysis have different features in different epochs. During the cold period (1957-1979), the leading mode is characterized by centers of extreme values of CWI in northern China; while during the warm period (1980-2009), the leading mode features two maximum loading centers over northern and southern China. The southward extension of the extreme value center is associated with an increase in the intensity of coldwave variations in southern China relative to previous decades. A multi-model ensemble of seven state-of-the-art climate models shows an extension of the maximum loading of the CWI leading mode into southern China by the end of the 21st century (2080-2099) under the A1B global warming scenario (atmospheric CO2 concentration of 720 ppm). These results indicate that the primary response of the leading mode of CWI to global warming might be a southward extension of the extreme value center. This response may be associated with the southward shift of the storm track observed during recent decades. A significant change in the baroclinic growth rates around 40°N is accompanied by a consistent change in synoptic eddies in the troposphere, which may indicate a shift in the preferred latitude for the growth of eddies. As a result, the storm track tends to move southward, suggesting that southern China may experience increased storminess due to increased baroclinic instability in the troposphere.

Ma, Tingting; Jiang, Zhihong; Wu, Zhiwei

2013-10-01

216

Change in abundance of pacific brant wintering in alaska: evidence of a climate warming effect?  

USGS Publications Warehouse

Winter distribution of Pacific Flyway brant (Branta bernicla nigricans) has shifted northward from lowtemperate areas to sub-Arctic areas over the last 42 years. We assessed the winter abundance and distribution of brant in Alaska to evaluate whether climate warming may be contributing to positive trends in the most northern of the wintering populations. Mean surface air temperatures during winter at the end of the Alaska Peninsula increased about 1??C between 1963 and 2004, resulting in a 23% reduction in freezing degree days and a 34% decline in the number of days when ice cover prevents birds from accessing food resources. Trends in the wintering population fluctuated with states of the Pacific Decadal Oscillation, increasing during positive (warm) phases and decreasing during negative (cold) phases, and this correlation provides support for the hypothesis that growth in the wintering population of brant in Alaska is linked to climate warming. The size of the wintering population was negatively correlated with the number of days of strong northwesterly winds in November, which suggests that the occurrence of tailwinds favorable for migration before the onset of winter was a key factor in whether brant migrated from Alaska or remained there during winter. Winter distribution of brant on the Alaska Peninsula was highly variable and influenced by ice cover, particularly at the heavily used Izembek Lagoon. Observations of previously marked brant indicated that the Alaska wintering population was composed primarily of birds originating from Arctic breeding colonies that appear to be growing. Numbers of brant in Alaska during winter will likely increase as temperatures rise and ice cover decreases at high latitudes in response to climate warming. ?? The Arctic Institute of North America.

Ward, D.H.; Dau, C.P.; Lee, T.; Sedinger, J.S.; Anderson, B.A.; Hines, J.E.

2009-01-01

217

Accounting for global-mean warming and scaling uncertainties in climate change impact studies Hydrol. Earth Syst. Sci., 11(3), 12071226, 2007  

E-print Network

Accounting for global-mean warming and scaling uncertainties in climate change impact studies 1207(s) 2007. This work is licensed under a Creative Commons License. Accounting for global-mean warming from a few regional climate model runs are scaled, based on different global-mean warming projections

Paris-Sud XI, Université de

218

Probability distributions for regional climate change from uncertain global mean warming and uncertain scaling relationship Hydrol. Earth Syst. Sci., 11(3), 10971114, 2007  

E-print Network

Probability distributions for regional climate change from uncertain global mean warming of probability distributions for regional climate change from uncertain global mean warming and an uncertain/precipitation per degree global mean warming. Each scaling variable is assumed to be normally distributed

Paris-Sud XI, Université de

219

Changing forest water yields in response to climate warming: results from long-term experimental watershed sites across North America.  

PubMed

Climate warming is projected to affect forest water yields but the effects are expected to vary. We investigated how forest type and age affect water yield resilience to climate warming. To answer this question, we examined the variability in historical water yields at long-term experimental catchments across Canada and the United States over 5-year cool and warm periods. Using the theoretical framework of the Budyko curve, we calculated the effects of climate warming on the annual partitioning of precipitation (P) into evapotranspiration (ET) and water yield. Deviation (d) was defined as a catchment's change in actual ET divided by P [AET/P; evaporative index (EI)] coincident with a shift from a cool to a warm period - a positive d indicates an upward shift in EI and smaller than expected water yields, and a negative d indicates a downward shift in EI and larger than expected water yields. Elasticity was defined as the ratio of interannual variation in potential ET divided by P (PET/P; dryness index) to interannual variation in the EI - high elasticity indicates low d despite large range in drying index (i.e., resilient water yields), low elasticity indicates high d despite small range in drying index (i.e., nonresilient water yields). Although the data needed to fully evaluate ecosystems based on these metrics are limited, we were able to identify some characteristics of response among forest types. Alpine sites showed the greatest sensitivity to climate warming with any warming leading to increased water yields. Conifer forests included catchments with lowest elasticity and stable to larger water yields. Deciduous forests included catchments with intermediate elasticity and stable to smaller water yields. Mixed coniferous/deciduous forests included catchments with highest elasticity and stable water yields. Forest type appeared to influence the resilience of catchment water yields to climate warming, with conifer and deciduous catchments more susceptible to climate warming than the more diverse mixed forest catchments. PMID:24757012

Creed, Irena F; Spargo, Adam T; Jones, Julia A; Buttle, Jim M; Adams, Mary B; Beall, Fred D; Booth, Eric G; Campbell, John L; Clow, Dave; Elder, Kelly; Green, Mark B; Grimm, Nancy B; Miniat, Chelcy; Ramlal, Patricia; Saha, Amartya; Sebestyen, Stephen; Spittlehouse, Dave; Sterling, Shannon; Williams, Mark W; Winkler, Rita; Yao, Huaxia

2014-10-01

220

Changing forest water yields in response to climate warming: results from long-term experimental watershed sites across North America  

PubMed Central

Climate warming is projected to affect forest water yields but the effects are expected to vary. We investigated how forest type and age affect water yield resilience to climate warming. To answer this question, we examined the variability in historical water yields at long-term experimental catchments across Canada and the United States over 5-year cool and warm periods. Using the theoretical framework of the Budyko curve, we calculated the effects of climate warming on the annual partitioning of precipitation (P) into evapotranspiration (ET) and water yield. Deviation (d) was defined as a catchment's change in actual ET divided by P [AET/P; evaporative index (EI)] coincident with a shift from a cool to a warm period – a positive d indicates an upward shift in EI and smaller than expected water yields, and a negative d indicates a downward shift in EI and larger than expected water yields. Elasticity was defined as the ratio of interannual variation in potential ET divided by P (PET/P; dryness index) to interannual variation in the EI – high elasticity indicates low d despite large range in drying index (i.e., resilient water yields), low elasticity indicates high d despite small range in drying index (i.e., nonresilient water yields). Although the data needed to fully evaluate ecosystems based on these metrics are limited, we were able to identify some characteristics of response among forest types. Alpine sites showed the greatest sensitivity to climate warming with any warming leading to increased water yields. Conifer forests included catchments with lowest elasticity and stable to larger water yields. Deciduous forests included catchments with intermediate elasticity and stable to smaller water yields. Mixed coniferous/deciduous forests included catchments with highest elasticity and stable water yields. Forest type appeared to influence the resilience of catchment water yields to climate warming, with conifer and deciduous catchments more susceptible to climate warming than the more diverse mixed forest catchments. PMID:24757012

Creed, Irena F; Spargo, Adam T; Jones, Julia A; Buttle, Jim M; Adams, Mary B; Beall, Fred D; Booth, Eric G; Campbell, John L; Clow, Dave; Elder, Kelly; Green, Mark B; Grimm, Nancy B; Miniat, Chelcy; Ramlal, Patricia; Saha, Amartya; Sebestyen, Stephen; Spittlehouse, Dave; Sterling, Shannon; Williams, Mark W; Winkler, Rita; Yao, Huaxia

2014-01-01

221

Ocean surface warming: The North Atlantic remains within the envelope of previous recorded conditions  

NASA Astrophysics Data System (ADS)

Anomalously warm air temperatures in various parts of the world have been widely noted in recent decades. In marine systems, biological indicators such as the range of plankton and fish have been used to indicate impacts of ocean warming, although for many regions recent ocean warming does not exceed short-term warming events over the last two centuries. Here we use International Comprehensive Ocean-Atmosphere Data Set (ICOADS) sea-surface temperature data to update analysis in the North Atlantic to show that present warm conditions are currently no more persistent than those encountered in the last 150 years. We show that the position of various isotherms, which play a central role in influencing the distribution of marine taxa ranging from plankton to fish and turtles, are more regularly found further north in recent years than at any time since the 1850s.

Hobson, Victoria J.; McMahon, Clive R.; Richardson, Anthony; Hays, Graeme C.

2008-02-01

222

Cold to Warm and Warm to Cold: A Comparison of rates and signatures of climate change going into and out of the Younger Dryas  

Microsoft Academic Search

The most recent, very large (15 degrees C change in mean annual temperature) and very abrupt (50 years or less) climate change recorded in Greenland ice cores is the end of the Younger Dryas (YD). While this cold to warm transition has been extensively studied in ice cores using tools such as stable isotopes in ice, gas concentrations, stable isotopes

T. Popp; J. White; A. Sveinbjornsdottir; V. Masson-Delmotte; S. Johnsen; J. Jouzel

2003-01-01

223

Tittel: An Alternative to the Global Warming Potential for Comparing Climate Impacts of Emissions of Greenhouse Gases Title: An Alternative to the Global Warming Potential for Comparing Climate Impacts of Emissions of Greenhouse Gases  

Microsoft Academic Search

The Global Warming Potential (GWP) is used within the Kyoto Protocol to the United Nations Framework Convention on Climate Change as a metric for weighting the climatic impact of emissions of different greenhouse gases. The GWP has been subject to many criticisms because of its formulation, but nevertheless it has retained some favour because of the simplicity of its design

Keith P. Shine; Jan S. Fuglestvedt; Nicola Stuber

224

Formability analysis of austenitic stainless steel-304 under warm conditions  

NASA Astrophysics Data System (ADS)

A warm deep drawing process of austenitic stainless steel-304 (ASS-304) of circular blanks with coupled ther mal analysis is studied in this article. 65 mm blanks were deep drawn at different temperatures and thickness distribution is experimentally measured after cutting the drawn component into two halves. The process is simulated using explicit fin ite element code LS-DYNA. A Barlat 3 parameter model is used in the simulation, as the material is anisotropic up to 30 0°C. Material properties for the simulation are determined at different temperatures using a 5 T UTM coupled with a furn ace. In this analysis constant punch speed and variable blank holder force (BHF) is applied to draw cups without wrinkle.

Lade, Jayahari; Singh, Swadesh Kumar; Banoth, Balu Naik; Gupta, Amit Kumar

2013-12-01

225

A geohydrologic framework for characterizing summer streamflow sensitivity to climate warming in the Pacific Northwest, USA  

NASA Astrophysics Data System (ADS)

Summer streamflows in the Pacific Northwest are largely derived from melting snow and groundwater discharge. As the climate warms, diminishing snowpack and earlier snowmelt will cause reductions in summer streamflow. Most assessments of the impacts of a changing climate to streamflow make use of downscaled temperature and precipitation projections from General Circulation Models (GCMs). Projected climate simulations from these GCMs are often too coarse for planning purposes, as they do not capture smaller scale topographic controls and other important watershed processes. This uncertainty is further amplified when downscaled climate predictions are coupled to macroscale hydrologic models that fail to capture streamflow contributions from deep groundwater. Deep aquifers play an important role in mediating streamflow response to climate change, and groundwater needs to be explicitly incorporated into sensitivity assessments. Here we develop and apply an analytical framework for characterizing summer streamflow sensitivity to a change in the timing and magnitude of recharge in a spatially-explicit fashion. Two patterns emerge from this analysis: first, areas with high streamflow sensitivity also have higher summer streamflows as compared to low sensitivity areas. Second, the level of sensitivity and spatial extent of highly sensitive areas diminishes over time as the summer progresses. Results of this analysis point to a robust, practical, and scalable approach that can help assess risk at the landscape scale, complement the downscaling approach, be applied to any climate scenario of interest, and provide a framework to assist land and water managers adapt to an uncertain and potentially challenging future.

Safeeq, M.; Grant, G. E.; Lewis, S. L.; Kramer, M. G.; Staab, B.

2014-03-01

226

Supraglacial lakes on the Greenland ice sheet advance inland under warming climate  

NASA Astrophysics Data System (ADS)

Supraglacial lakes (SGLs) form annually on the Greenland ice sheet and, when they drain, their discharge enhances ice-sheet flow by lubricating the base and potentially by warming the ice. Today, SGLs tend to form within the ablation zone, where enhanced lubrication is offset by efficient subglacial drainage. However, it is not clear what impact a warming climate will have on this arrangement. Here, we use an SGL initiation and growth model to show that lakes form at higher altitudes as temperatures rise, consistent with satellite observations. Our simulations show that in southwest Greenland, SGLs spread 103 and 110 km further inland by the year 2060 under moderate (RCP 4.5) and extreme (RCP 8.5) climate change scenarios, respectively, leading to an estimated 48-53% increase in the area over which they are distributed across the ice sheet as a whole. Up to half of these new lakes may be large enough to drain, potentially delivering water and heat to the ice-sheet base in regions where subglacial drainage is inefficient. In such places, ice flow responds positively to increases in surface water delivered to the bed through enhanced basal lubrication and warming of the ice, and so the inland advance of SGLs should be considered in projections of ice-sheet change.

Leeson, A. A.; Shepherd, A.; Briggs, K.; Howat, I.; Fettweis, X.; Morlighem, M.; Rignot, E.

2015-01-01

227

Global climate warming on climate and agriculture in western Liaoning impact  

Microsoft Academic Search

Objective) This paper focuses on analyzing the energy resources and precipitation trends to the context of global warming in the western Liaoning Province in recent 60 years, where located in the northern hemisphere. Provide the basis study for the adjustment of agricultural structure and full use of energy resources.(Method) Use meteorological data of three cities in western Liaoning Province during

Guang-Xue Zhou; Pu-qing Li; Xiao-dong Zhou

2011-01-01

228

Reproductive and physiological responses to simulated climate warming for four subalpine species.  

PubMed

* The carbon costs of reproduction were examined in four subalpine herbaceous plant species for which number and size of flowers respond differently under a long-term infrared warming experiment. * Instantaneous measurements of gas exchange and an integrative model were used to calculate whole-plant carbon budgets and reproductive effort (RE). * Of the two species for which flowering was reduced, only one (Delphinium nuttallianum) exhibited higher RE under warming. The other species (Erythronium grandiflorum) flowers earlier when freezing events under warming treatment could have damaged floral buds. Of the two species for which flowering rates were not reduced, one (Helianthella quinquenervis) had higher RE, while RE was unaffected for the other (Erigeron speciosus). Each of these different responses was the result of a different combination of changes in organ size and physiological rates in each of the species. * Results show that the magnitude and direction of responses to warming differ greatly among species. Such results demonstrate the importance of examining multiple species to understand the complex interactions among physiological and reproductive responses to climate change. PMID:17176399

Lambrecht, Susan C; Loik, Michael E; Inouye, David W; Harte, John

2007-01-01

229

Enhancing Primary School Students' Knowledge about Global Warming and Environmental Attitude Using Climate Change Activities  

ERIC Educational Resources Information Center

Climate change generally and global warming specifically have become a common feature of the daily news. Due to widespread recognition of the adverse consequences of climate change on human lives, concerted societal effort has been taken to address it (e.g. by means of the science curriculum). This study was designed to test the effect that…

Karpudewan, Mageswary; Roth, Wolff-Michael; Bin Abdullah, Mohd Nor Syahrir

2015-01-01

230

Predicting spring phenology and frost damage risk of Betula spp. under climatic warming: a comparison of two models  

Microsoft Academic Search

Summary Timing of bud burst and frost damage risk for leaves of Betula spp. in response to climatic warming in Fin- land was examined with two models. In the first model, onto- genetic development in spring was triggered by an accumula- tion of chilling temperatures. The second model assumed an additional signal from the light climate. The two models gave

TAPIO LINKOSALO; TIMOTHY R. CARTER; RISTO HÄKKINEN; PERTTI HARI

231

The cumulative effects of climate warming and other human stresses on Canadian freshwaters in the new millennium  

Microsoft Academic Search

Climate warming will adversely affect Canadian water quality and water quantity. The magnitude and timing of river flows and lake levels and water renewal times will change. In many regions, wetlands will disappear and water tables will decline. Habitats for cold stenothermic organisms will be reduced in small lakes. Warmer temperatures will affect fish migrations in some regions. Climate will

D. W. Schindler

2001-01-01

232

The effect of global warming and global cooling on the distribution of the latest Permian climate zones  

Microsoft Academic Search

The end-Permian biotic crisis is commonly associated with rapid and severe climatic changes. These climatic changes are commonly suggested to have originated from solid Earth carbon degassing (leading to global warming), but aerosol- and ash-induced cooling induced by lava degassing has been suggested as well. The application of an Earth System Model of Intermediate Complexity has enabled a visualisation of

Marco Roscher; Frode Stordal; Henrik Svensen

2011-01-01

233

Thermal thresholds as predictors of seed dormancy release and germination timing: altitude-related risks from climate warming for the wild grapevine Vitis vinifera subsp. sylvestris  

PubMed Central

Background and Aims The importance of thermal thresholds for predicting seed dormancy release and germination timing under the present climate conditions and simulated climate change scenarios was investigated. In particular, Vitis vinifera subsp. sylvestris was investigated in four Sardinian populations over the full altitudinal range of the species (from approx. 100 to 800 m a.s.l). Methods Dried and fresh seeds from each population were incubated in the light at a range of temperatures (10–25 and 25/10 °C), without any pre-treatment and after a warm (3 months at 25 °C) or a cold (3 months at 5 °C) stratification. A thermal time approach was then applied to the germination results for dried seeds and the seed responses were modelled according to the present climate conditions and two simulated scenarios of the Intergovernmental Panel on Climate Change (IPCC): B1 (+1·8 °C) and A2 (+3·4 °C). Key Results Cold stratification released physiological dormancy, while very few seeds germinated without treatments or after warm stratification. Fresh, cold-stratified seeds germinated significantly better (>80 %) at temperatures ?20 °C than at lower temperatures. A base temperature for germination (Tb) of 9·0–11·3 °C and a thermal time requirement for 50 % of germination (?50) ranging from 33·6 °Cd to 68·6 °Cd were identified for non-dormant cold-stratified seeds, depending on the populations. This complex combination of thermal requirements for dormancy release and germination allowed prediction of field emergence from March to May under the present climatic conditions for the investigated populations. Conclusions The thermal thresholds for seed germination identified in this study (Tb and ?50) explained the differences in seed germination detected among populations. Under the two simulated IPCC scenarios, an altitude-related risk from climate warming is identified, with lowland populations being more threatened due to a compromised seed dormancy release and a narrowed seed germination window. PMID:23071219

Orrù, Martino; Mattana, Efisio; Pritchard, Hugh W.; Bacchetta, Gianluigi

2012-01-01

234

Mass extinctions, atmospheric sulphur and climatic warming at the K/T boundary  

NASA Technical Reports Server (NTRS)

The possible climatic effects of a drastic decrease in cloud condensation nuclei (CCN) associated with a severe reduction in the global marine phytoplankton abundance are investigated. Calculations suggest that a reduction in CCN of more than 80 percent and the resulting decrease in marine cloud albedo could have produced a rapid global warming of 6 C or more. Oxygen isotope analyses of marine sediments from many parts of the world have been interpreted as indicating a marked warming coincident with the demise of calcareous nannoplankton at the K/T boundary. Decreased marine cloud albedo and resulting high sea surface temperatures could have been a factor in the maintenance of low productivity in the 'Strangelove Ocean' period following the K/T extinctions.

Rampino, Michael R.; Volk, Tyler

1988-01-01

235

Climate change. Projected increase in lightning strikes in the United States due to global warming.  

PubMed

Lightning plays an important role in atmospheric chemistry and in the initiation of wildfires, but the impact of global warming on lightning rates is poorly constrained. Here we propose that the lightning flash rate is proportional to the convective available potential energy (CAPE) times the precipitation rate. Using observations, the product of CAPE and precipitation explains 77% of the variance in the time series of total cloud-to-ground lightning flashes over the contiguous United States (CONUS). Storms convert CAPE times precipitated water mass to discharged lightning energy with an efficiency of 1%. When this proxy is applied to 11 climate models, CONUS lightning strikes are predicted to increase 12 ± 5% per degree Celsius of global warming and about 50% over this century. PMID:25395536

Romps, David M; Seeley, Jacob T; Vollaro, David; Molinari, John

2014-11-14

236

Do cities simulate climate change? A comparison of herbivore response to urban and global warming  

USGS Publications Warehouse

Cities experience elevated temperature, CO2, and nitrogen deposition decades ahead of the global average, such that biological response to urbanization may predict response to future climate change. This hypothesis remains untested due to a lack of complementary urban and long-term observations. Here, we examine the response of an herbivore, the scale insect Melanaspis tenebricosa, to temperature in the context of an urban heat island, a series of historical temperature fluctuations, and recent climate warming. We survey M. tenebricosa on 55 urban street trees in Raleigh, NC, 342 herbarium specimens collected in the rural southeastern United States from 1895 to 2011, and at 20 rural forest sites represented by both modern (2013) and historical samples. We relate scale insect abundance to August temperatures and find that M. tenebricosa is most common in the hottest parts of the city, on historical specimens collected during warm time periods, and in present-day rural forests compared to the same sites when they were cooler. Scale insects reached their highest densities in the city, but abundance peaked at similar temperatures in urban and historical datasets and tracked temperature on a decadal scale. Although urban habitats are highly modified, species response to a key abiotic factor, temperature, was consistent across urban and rural-forest ecosystems. Cities may be an appropriate but underused system for developing and testing hypotheses about biological effects of climate change. Future work should test the applicability of this model to other groups of organisms.

Youngsteadt, Elsa; Dale, Adam G.; Terando, Adam J.; Dunn, Robert R.; Frank, Steven D.

2014-01-01

237

Do cities simulate climate change? A comparison of herbivore response to urban and global warming.  

PubMed

Cities experience elevated temperature, CO2 , and nitrogen deposition decades ahead of the global average, such that biological response to urbanization may predict response to future climate change. This hypothesis remains untested due to a lack of complementary urban and long-term observations. Here, we examine the response of an herbivore, the scale insect Melanaspis tenebricosa, to temperature in the context of an urban heat island, a series of historical temperature fluctuations, and recent climate warming. We survey M. tenebricosa on 55 urban street trees in Raleigh, NC, 342 herbarium specimens collected in the rural southeastern United States from 1895 to 2011, and at 20 rural forest sites represented by both modern (2013) and historical samples. We relate scale insect abundance to August temperatures and find that M. tenebricosa is most common in the hottest parts of the city, on historical specimens collected during warm time periods, and in present-day rural forests compared to the same sites when they were cooler. Scale insects reached their highest densities in the city, but abundance peaked at similar temperatures in urban and historical datasets and tracked temperature on a decadal scale. Although urban habitats are highly modified, species response to a key abiotic factor, temperature, was consistent across urban and rural-forest ecosystems. Cities may be an appropriate but underused system for developing and testing hypotheses about biological effects of climate change. Future work should test the applicability of this model to other groups of organisms. PMID:25163424

Youngsteadt, Elsa; Dale, Adam G; Terando, Adam J; Dunn, Robert R; Frank, Steven D

2015-01-01

238

Climate Warming May Facilitate Invasion of the Exotic Shrub Lantana camara  

PubMed Central

Plant species show different responses to the elevated temperatures that are resulting from global climate change, depending on their ecological and physiological characteristics. The highly invasive shrub Lantana camara occurs between the latitudes of 35°N and 35°S. According to current and future climate scenarios predicted by the CLIMEX model, climatically suitable areas for L. camara are projected to contract globally, despite expansions in some areas. The objective of this study was to test those predictions, using a pot experiment in which branch cuttings were grown at three different temperatures (22°C, 26°C and 30°C). We hypothesized that warming would facilitate the invasiveness of L. camara. In response to rising temperatures, the total biomass of L. camara did increase. Plants allocated more biomass to stems and enlarged their leaves more at 26°C and 30°C, which promoted light capture and assimilation. They did not appear to be stressed by higher temperatures, in fact photosynthesis and assimilation were enhanced. Using lettuce (Lactuca sativa) as a receptor plant in a bioassay experiment, we also tested the phytotoxicity of L. camara leachate at different temperatures. All aqueous extracts from fresh leaves significantly inhibited the germination and seedling growth of lettuce, and the allelopathic effects became stronger with increasing temperature. Our results provide key evidence that elevated temperature led to significant increases in growth along with physiological and allelopathic effects, which together indicate that global warming facilitates the invasion of L. camara. PMID:25184224

Zhang, Qiaoying; Zhang, Yunchun; Peng, Shaolin; Zobel, Kristjan

2014-01-01

239

Adaptation to Global Warming: Do Climate Models Tell Us What We Need to Know? Author(s): Naomi Oreskes, David A. Stainforth, Leonard A. Smith  

E-print Network

Adaptation to Global Warming: Do Climate Models Tell Us What We Need to Know? Author(s): Naomi. All rights reserved. 1012 Adaptation to Global Warming: Do Climate Models Tell Us What We Need to Know discussion in scientific and policy circles of the need for adaptation to climate change. These arguments

Stevenson, Paul

240

Regional climate response to land surface changes after harvest in the North China Plain under present and possible future climate conditions  

NASA Astrophysics Data System (ADS)

this study, we investigated the impacts of land use alterations from harvesting practices on the regional surface climate over the North China Plain. The surface climate responses after harvest in June in regions where double-cropping is practiced were evaluated using observations and model simulations with the global climate model HadGEM2-Atmosphere. Responses were modeled under both present and possible future climate conditions. In the model, double-cropping was represented using the monthly varying fraction of vegetation. This contributed to an improvement in the model simulation over East Asia. Modeling results showed that the land surface was warmer and drier after harvest, and these simulation results were consistent with observations. The bare soil surface after harvest in June had biophysical impacts on the surface climate that were mediated by decreasing evapotranspiration and latent heat flux effects, which increased surface air temperatures and decreased surface humidity. An increase in shortwave radiation also contributed to the rise in temperatures. Under two Representative Concentration Pathways (RCP) scenarios for possible future climate conditions, land conversion induced additional warming in addition to greenhouse gases induced global warming. The RCP 8.5 and RCP 2.6 scenarios demonstrated a warming of 1.0°C and 1.4°C due to harvesting practices in June, respectively. The response magnitude was affected by the climate conditions in each RCP. Our results suggest that potential impacts of harvest on the local climate need to be considered in future projections of CO2-induced warming on a regional scale.

Cho, Mee-Hyun; Boo, Kyung-On; Lee, Johan; Cho, Chunho; Lim, Gyu-Ho

2014-04-01

241

Amazon Basin climate under global warming: the role of the sea surface temperature.  

PubMed

The Hadley Centre coupled climate-carbon cycle model (HadCM3LC) predicts loss of the Amazon rainforest in response to future anthropogenic greenhouse gas emissions. In this study, the atmospheric component of HadCM3LC is used to assess the role of simulated changes in mid-twenty-first century sea surface temperature (SST) in Amazon Basin climate change. When the full HadCM3LC SST anomalies (SSTAs) are used, the atmosphere model reproduces the Amazon Basin climate change exhibited by HadCM3LC, including much of the reduction in Amazon Basin rainfall. This rainfall change is shown to be the combined effect of SSTAs in both the tropical Atlantic and the Pacific, with roughly equal contributions from each basin. The greatest rainfall reduction occurs from May to October, outside of the mature South American monsoon (SAM) season. This dry season response is the combined effect of a more rapid warming of the tropical North Atlantic relative to the south, and warm SSTAs in the tropical east Pacific. Conversely, a weak enhancement of mature SAM season rainfall in response to Atlantic SST change is suppressed by the atmospheric response to Pacific SST. This net wet season response is sufficient to prevent dry season soil moisture deficits from being recharged through the SAM season, leading to a perennial soil moisture reduction and an associated 30% reduction in annual Amazon Basin net primary productivity (NPP). A further 23% NPP reduction occurs in response to a 3.5 degrees C warmer air temperature associated with a global mean SST warming. PMID:18267896

Harris, Phil P; Huntingford, Chris; Cox, Peter M

2008-05-27

242

The influence of convection parameterisations under alternate climate conditions  

NASA Astrophysics Data System (ADS)

In the last decades several convection parameterisations have been developed to consider the impact of small-scale unresolved processes in Earth System Models associated with convective clouds. Global model simulations, which have been performed under current climate conditions with different convection schemes, significantly differ among each other in the simulated precipitation patterns due to the parameterisation assumptions and formulations, e.g. the simplified treatment of the cloud microphysics. Additionally, the simulated transport of short-lived trace gases strongly depends on the chosen convection parameterisation due to the differences in the vertical redistribution of mass. Furthermore, other meteorological parameters like the temperature or the specific humidity show substantial differences in convectively active regions. This study presents uncertainties of climate change scenarios caused by different convection parameterisations. For this analysis two experiments (reference simulation with a CO2 concentration of 348 ppm; 2xCO2-simulation with a CO2 concentration of 696 ppm) are calculated with the ECHAM/MESSy atmospheric chemistry (EMAC) model applying four different convection schemes (Tiedtke, ECMWF, Emanuel and Zhang-McFarlane - Hack) and two resolutions (T42 and T63), respectively. The results indicate that the equilibrium climate sensitivity is independent of the chosen convection parameterisation. However, the regional temperature increase, induced by a doubling of the carbon dioxide concentration, demonstrates differences of up to a few Kelvin at the surface as well as in the UTLS for the ITCZ region depending on the selected convection parameterisation. The interaction between cloud and convection parameterisations results in a large disagreement of precipitation patterns. Although every 2xCO2 -experiment simulates an increase in global mean precipitation rates, the change of regional precipitation patterns differ widely. Finally, analysing the cloud radiative forcing a huge spread of the cloud-induced radiative flux change is found in the warm pool region due to a change of the convection parameterisation.

Rybka, Harald; Tost, Holger

2013-04-01

243

Competitive and demographic leverage points of community shifts under climate warming  

PubMed Central

Accelerating rates of climate change and a paucity of whole-community studies of climate impacts limit our ability to forecast shifts in ecosystem structure and dynamics, particularly because climate change can lead to idiosyncratic responses via both demographic effects and altered species interactions. We used a multispecies model to predict which processes and species' responses are likely to drive shifts in the composition of a space-limited benthic marine community. Our model was parametrized from experimental manipulations of the community. Model simulations indicated shifts in species dominance patterns as temperatures increase, with projected shifts in composition primarily owing to the temperature dependence of growth, mortality and competition for three critical species. By contrast, warming impacts on two other species (rendering them weaker competitors for space) and recruitment rates of all species were of lesser importance in determining projected community changes. Our analysis reveals the importance of temperature-dependent competitive interactions for predicting effects of changing climate on such communities. Furthermore, by identifying processes and species that could disproportionately leverage shifts in community composition, our results contribute to a mechanistic understanding of climate change impacts, thereby allowing more insightful predictions of future biodiversity patterns. PMID:23658199

Sorte, Cascade J. B.; White, J. Wilson

2013-01-01

244

Warm Rain Processes Over the Tropical Oceans and Implications on Climate Change: Results from TRMM and GOES GCM  

NASA Technical Reports Server (NTRS)

In this talk, we will first show results from TRMM data regarding the characteristics of warm rains over the tropical oceans, and the dependence of rate of warm rain production on sea surface temperature. Results lead to the hypothesis that warm rain production efficiency, i.e., autoconversion, may be increased in a warm climate. We use the GEOS-II GCM to test this hypothesis. Our modeling results show that in a climate with increased rate of autoconversion, the total rain amount is increased, with warm rain contributing to a larger portion of the increase. The abundant rainout of warm precipitation causes a reduction of low and middle cloud amount due to rainout, and reduced high clouds due to less water vapor available for ice-phase convection. However, clod radiation feedback caused by the increased rainfall efficiency, leads to differential vertical heating/cooling producing a more unstable atmosphere, allowing, more intense, but isolated penetrative convection, with contracted anvils to develop. Results also show that increased autoconversion reduces the convective adjustment time scale, resulting in faster recycling of atmospheric water. Most interestingly, the increased low level heating associated with warm rain leads to more energetic Madden and Julian oscillations in the tropics, with well-defined eastward propagation. While reducing the autoconversion leads to an abundant mix of westward and eastward tropical disturbances on daily to weekly time scales. The crucial link of precipitation microphysical processes to climate change including the effects of aerosols will be discussed.

Lau, William K. M.; Wu, H. T.

2004-01-01

245

Warm Rain Processes over the Tropical Oceans and Implications on Climate Change: Results from TRMM and GEOS GCM  

NASA Technical Reports Server (NTRS)

In this talk, we will first show results from TRMM data regarding the characteristics of warm rains over the tropical oceans, and the dependence of rate of warm rain production on sea surface temperature. Results lead to the hypothesis that warm rain production efficiency, i.e., autoconversion, may be increased in a warm climate. We use the GEOS-II GCM to test this hypothesis. Our modeling results show that in a climate with increased rate of autoconversion, the total rain amount is increased, with warm rain contributing to larger portion of the increase. The abundant rainout of warm precipitation causes a reduction of low and middle cloud amount due to rainout, and reduced high clouds due to less water vapor available for ice-phase convection. However, clod radiation feedback caused by the increased rainfall efficiency, leads to differential vertical heating/cooling producing a more unstable atmosphere, allowing, more intense, but isolated penetrative convection, with contracted anvils to develop. Results also show that increased autoconversion reduces the convective adjustment time scale, resulting in faster recycling of atmospheric water. Most interestingly, the increased low level heating associated with warm rain leads to more energetic Madden and Julian oscillations in the tropics, with well-defined eastward propagation. While reducing the autoconversion leads to an abundant mix of westward and eastward tropical disturbances on daily to weekly time scales. The crucial link of precipitation microphysical processes to climate change including the effects of aerosols will be discussed.

Lau, William K. M.; Wu, H. T.

2004-01-01

246

A paleoscience approach to estimating the effects of climatic warming on salmonid fisheries of the Columbia River Basin  

SciTech Connect

To understand how climatic warming might affect salmonid populations, we are following a four-step procedure, incorporating paleoenvironmental data at the beginning and ending points, as follows. First, we used geomorphic, paleobotanical, and paleomalacological data to reconstruct stream conditions during the last 8000 years. Second, we estimated the effect on salmon of conditions extant approximately 6000 to 7000 radiocarbon years before present (B.P.), when temperatures were as much as 2[degrees]C warmer than at present. This became an analog of future warmer climate and its effects on spawning, incubation, and rearing parameters of the NPPC's Tributary Parameter Model (TPM) for estimating salmoned production. Third, we ran the TPM in conjunction with the NPPC System Planning Model (SPM) to calculate the effect of these analog conditions on the population of returning adult fish in selected stream systems. Ultimately, we will run the models for all salmon-accessible subbasins of the Columbia River system. Finally, we are identifying fish remains obtained from archaeological sites along the Columbia River to compare variations in the taxonomic composition of ancient fish assemblages with model predictions.

Chatters, J.C.; Butler, V.L.; Scott, M.J.; Anderson, D.M.; Neitzel, D.A.

1992-10-01

247

A paleoscience approach to estimating the effects of climatic warming on salmonid fisheries of the Columbia River Basin  

SciTech Connect

To understand how climatic warming might affect salmonid populations, we are following a four-step procedure, incorporating paleoenvironmental data at the beginning and ending points, as follows. First, we used geomorphic, paleobotanical, and paleomalacological data to reconstruct stream conditions during the last 8000 years. Second, we estimated the effect on salmon of conditions extant approximately 6000 to 7000 radiocarbon years before present (B.P.), when temperatures were as much as 2{degrees}C warmer than at present. This became an analog of future warmer climate and its effects on spawning, incubation, and rearing parameters of the NPPC`s Tributary Parameter Model (TPM) for estimating salmoned production. Third, we ran the TPM in conjunction with the NPPC System Planning Model (SPM) to calculate the effect of these analog conditions on the population of returning adult fish in selected stream systems. Ultimately, we will run the models for all salmon-accessible subbasins of the Columbia River system. Finally, we are identifying fish remains obtained from archaeological sites along the Columbia River to compare variations in the taxonomic composition of ancient fish assemblages with model predictions.

Chatters, J.C.; Butler, V.L.; Scott, M.J.; Anderson, D.M.; Neitzel, D.A.

1992-10-01

248

Relative effects of multi-decadal climatic variability and changes in the mean and variability of climate due to global warming: future streamflows in Britain  

Microsoft Academic Search

Climate change impact assessments conventionally assess just the implications of a change in mean climate due to global warming. This paper compares such effects of such changes with those due to natural multi-decadal variability, and also explores the effects of changing the year-to-year variability in climate as well as the mean. It estimates changes in mean monthly flows and a

Nigel W Arnell

2003-01-01

249

Impact of climate warming-induced increase in drought stress on successional dynamic of a coniferous forest within a dry inner Alpine environment  

NASA Astrophysics Data System (ADS)

Climate sensitivity of tree growth will effect the development of forest ecosystems under a warmer and drier climate by changing species composition and inducing shifts in forest distribution. We applied dendroclimatological techniques to determine impact of climate warming on radial stem growth of three native and widespread coniferous tree species of the central Austrian Alps (Norway spruce, Picea abies; European larch, Larix decidua; Scots pine, Pinus sylvestris), which grow intermixed at dry-mesic sites within a dry inner Alpine environment (750 m a.s.l., Tyrol, Austria). Time series of annual increments were developed from > 250 saplings and mature trees. Radial growth response to recent climate warming was explored by means of moving response functions (MRF) and evaluation of trends in basal area increment (BAI) for the period 1911 - 2009. Climate-growth relationships revealed significant differences among species in response to water availability. While precipitation in May - June favoured radial growth of spruce and larch, Scots pine growth mainly depended on April - May precipitation. Spruce growth was most sensitive to May - June temperature (inverse relationship). Although MRF coefficients indicated increasing drought sensitivity of all species, which is most likely related to intensified belowground competition for scarce water with increasing stand density and higher evapotranspiration rates due to climate warming, recent BAI trends strikingly differed among species. While BAI of larch was distinctly declining, spruce showed steadily increasing BAI and quite constant BAI was maintained in drought adapted Scots pine, although at lowest level of all species. Furthermore, more favourable growing conditions of spruce in recent decades are indicated by scattered natural regeneration and higher growth rates of younger trees during first decades of their lifespan. Because human interference and wildlife stock is negligible within the study area, results suggest a competitive advantage of shade-tolerant and shallow-rooted late successional spruce over early successional species, whereby the spruce`s competitive strength is most likely related to synergistic effects of shade-tolerance and efficient uptake of small rainfall events by fine roots distributed primarily in upper soil layers. On the other hand, strikingly decreasing trend in BAI of larch is suggested to be due to negative influence of climate warming on tree water status. We conclude that climate warming-induced increase in drought sensitivity changed competitive strength of co-occurring conifers due to differences in inherent adaptive capacity at a drought-prone inner Alpine site.

Schuster, R.; Zeisler, B.; Oberhuber, W.

2012-04-01

250

Examining Impact of Global warming on the summer monsoon system using regional Climate Model (PRECIS)  

NASA Astrophysics Data System (ADS)

Every year, southwest monsoon arrives over Indian region with remarkable regularity. It hits the southern state of Kerala first by the end of May or the early June. More than 70% of the annual precipitation is received during the four monsoon months viz. June to September. This monsoon rainfall is vital for the agriculture as well as for the yearly needs of Indian population. The performance of the monsoon depends on the timely onset over southern tip of India and its progress along the entire country. This northward progression of monsoon to cover the entire Indian landmass, many times, is associated with the formation of synoptic scale system in the Bay of Bengal region and their movement along the monsoon trough region. The analysis of the observed cyclonic disturbances show that their frequency has reduced in recent decades. It is, therefore, necessary to assess the effect of global warming on the monsoon climate of India. A state-of-art regional climate modelling system, known as PRECIS (Providing REgional Climates for Impacts Studies) developed by the Hadley Centre for Climate Prediction and Research, U.K. is applied over the South Asian domain to investigate the impact of global warming on the cyclonic disturbances. The PRECIS simulations at 50 km x 50 km horizontal resolution are made for two time slices, present (1961-1990) and the future (2071-2100), for two socio-economic scenarios A2 and B2. The model skills are evaluated using observed precipitation and surface air temperature. The model has shown reasonably good skill in simulating seasonal monsoon rainfall, whereas cold bias is seen in surface air temperature especially in post-monsoon months. The typical monsoon features like monsoon trough, precipitation maxima over west coast and northeast India are well simulated by the model. The model simulations under the scenarios of increasing greenhouse gas concentrations and sulphate aerosols are analysed to study the likely changes in the quasi-permanent systems related to the monsoon climate over India viz. monsoon circulation, heat low over northwest India, mean sea level pressures along monsoon trough region, towards the end of the 21st century. The analysis of the model outputs indicate the weakening of monsoon circulation in the future. The mean sea level pressures in head bay of Bengal regions may be higher in future indicating the less frequent cyclonic disturbances in the Bay of Bengal region, under the effect of global warming.

Patwardhan, S. K.; Kundeti, K.; Krishna Kumar, K.

2011-12-01

251

Improving the effectiveness of communication about climate science: Insights from the "Global Warming's Six Americas" audience segmentation research project  

NASA Astrophysics Data System (ADS)

That the climate science community has not been entirely effective in sharing what it knows about climate change with the broader public - and with policy makers and organizations that should be considering climate change when making decisions - is obvious. Our research shows that a large majority of the American public trusts scientists (76%) and science-based agencies (e.g., 76% trust NOAA) as sources of information about climate change. Yet, despite the widespread agreement in the climate science community that the climate is changing as a result of human activity, only 64% of the public understand that the world's average temperature has been increasing (and only about half of them are sure), less than half (47%) understand that the warming is caused mostly by human activity, and only 39% understand that most scientists think global warming is happening (in fact, only 13% understand that the large majority of climate scientists think global warming is happening). Less obvious is what the climate science community should do to become more effective in sharing what it knows. In this paper, we will use evidence from our "Global Warming's Six Americas" audience segmentation research project to suggest ways that individual climate scientists -- and perhaps more importantly, ways in which climate science agencies and professional societies -- can enhance the effectiveness of their communication efforts. We will conclude by challenging members of the climate science community to identify and convey "simple, clear messages, repeated often, by a variety of trusted sources" - an approach to communication repeatedly shown to be effective by the public health community.

Maibach, E.; Roser-Renouf, C.

2011-12-01

252

Global Warming: Early Warning Signs  

NSDL National Science Digital Library

This science-based world map depicts the local and regional consequences of global climate change. It identifies direct manifestations of a warming trend (fingerprints), and events that are consistent with the projections for global climate change and are likely to become more frequent and widespread with continued warming (harbingers). These signs are linked to a full description of conditions in that part of the world which indicate warming. A curriculum guide engages students in an exploration of the impacts of global climate change.

253

A warm and wet Little Climatic Optimum and a cold and dry Little Ice Age in the southern Rocky Mountains, USA  

SciTech Connect

In the next century, increases in atmospheric trace gas concentration could warm the global average temperature beyond what it has ranged during the past century. Examination of larger-than-historic climatic changes that have occurred in the past in specific regions provides realistic context for evaluating such potential future changes. This paper has contrasted the climatic manifestation of the Little Climatic Optimum or Medieval Warm Period (AD 900--1300) with that of the Little Ice Age (AD 1300--1850) in the northern Colorado Plateau region of the southwestern USA. The zenith of the Anasazi occupation coincides with the former and their demise coincides with the latter, when conditions became too cold and especially dry (in the summer) to support upland dry farming. During the height of the Little Climatic Optimum the region was characterized by a relatively long growing season and greater winter and summer precipitation than that of today. This resulted in a relatively rapid development of a potential dry-farming belt that was twice as wide as the present and areas that cannot be dry farmed today were routinely farmed by the Anasazi. Such conditions would be beneficial to dry farmers in the Four Corners region if those conditions were repeated in the near future.

Petersen, K.L.

1992-05-01

254

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

NASA Astrophysics Data System (ADS)

The Arctic is a complex system with strong interconnectedness among system components. Understanding the responses of the arctic tundra biome to a changing climate requires knowledge of the complex interactions among climate, soils, and the biological system. In this study, we investigate the individual and interactive effects of projected climate change and reindeer/caribou grazing across a variety of climate zones and soil nutrient levels on tundra plant community dynamics using an arctic vegetation model - ArcVeg. Our research questions include: 1) How does soil nutrient availability affect tundra vegetation responses to projected climate warming? 2) How does grazing affect tundra vegetation responses? 3) How do interactions of soil nutrients, climate warming and grazing affect tundra vegetation? We based our simulations on A1B scenario temperature data from the Intergovernmental Panel on Climate Change (IPCC), soil organic nitrogen data from Terrestrial Ecosystem Model (TEM) simulations and grazing pressure derived from reindeer/caribou population data from the CircumArctic Rangifer Monitoring and Assessment Network (CARMA). We found that in general tundra communities responded to warming with increased plant biomass, but the magnitude of the response is affected by the bioclimate zones, warming magnitude, available soil nutrients and grazing pressures. Regions with greater soil organic nitrogen responded to warming with greater biomass increase, Low Arctic tundra tended to have greater biomass increase than High Arctic tundra due to greater shrub abundance. However, such responses are mitigated by grazing. Regions with greater reindeer population and thus greater grazing intensity tended to have stronger negative effects on plant responses to warming than regions with less grazing. For example, in Subzone D, total biomass and NPP increases due to warming were about 71% and 43% in an Alaskan low grazing-intensity region, but 63% and 36% in a northwestern Canada high grazing-intensity region. In Subzone C, although with similar warming magnitude, Yamal and Taymyr region being intensely grazed by reindeer responded with smaller total biomass increase (~68%) than a northwestern Canada low grazing-intensity region (~93%). Plant responses to warming may be a factor that determines the size of reindeer population and understanding how tundra plants respond to warming, grazing and their interactions will contribute to reindeer management practices.

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

2011-12-01

255

Native bees buffer the negative impact of climate warming on honey bee pollination of watermelon crops.  

PubMed

If climate change affects pollinator-dependent crop production, this will have important implications for global food security because insect pollinators contribute to production for 75% of the leading global food crops. We investigate whether climate warming could result in indirect impacts upon crop pollination services via an overlooked mechanism, namely temperature-induced shifts in the diurnal activity patterns of pollinators. Using a large data set on bee pollination of watermelon crops, we predict how pollination services might change under various climate change scenarios. Our results show that under the most extreme IPCC scenario (A1F1), pollination services by managed honey bees are expected to decline by 14.5%, whereas pollination services provided by most native, wild taxa are predicted to increase, resulting in an estimated aggregate change in pollination services of +4.5% by 2099. We demonstrate the importance of native biodiversity in buffering the impacts of climate change, because crop pollination services would decline more steeply without the native, wild pollinators. More generally, our study provides an important example of how biodiversity can stabilize ecosystem services against environmental change. PMID:23704044

Rader, Romina; Reilly, James; Bartomeus, Ignasi; Winfree, Rachael

2013-10-01

256

Functional traits predict relationship between plant abundance dynamic and long-term climate warming.  

PubMed

Predicting climate change impact on ecosystem structure and services is one of the most important challenges in ecology. Until now, plant species response to climate change has been described at the level of fixed plant functional types, an approach limited by its inflexibility as there is much interspecific functional variation within plant functional types. Considering a plant species as a set of functional traits greatly increases our possibilities for analysis of ecosystem functioning and carbon and nutrient fluxes associated therewith. Moreover, recently assembled large-scale databases hold comprehensive per-species data on plant functional traits, allowing a detailed functional description of many plant communities on Earth. Here, we show that plant functional traits can be used as predictors of vegetation response to climate warming, accounting in our test ecosystem (the species-rich alpine belt of Caucasus mountains, Russia) for 59% of variability in the per-species abundance relation to temperature. In this mountain belt, traits that promote conservative leaf water economy (higher leaf mass per area, thicker leaves) and large investments in belowground reserves to support next year's shoot buds (root carbon content) were the best predictors of the species increase in abundance along with temperature increase. This finding demonstrates that plant functional traits constitute a highly useful concept for forecasting changes in plant communities, and their associated ecosystem services, in response to climate change. PMID:24145400

Soudzilovskaia, Nadejda A; Elumeeva, Tatiana G; Onipchenko, Vladimir G; Shidakov, Islam I; Salpagarova, Fatima S; Khubiev, Anzor B; Tekeev, Dzhamal K; Cornelissen, Johannes H C

2013-11-01

257

Functional traits predict relationship between plant abundance dynamic and long-term climate warming  

PubMed Central

Predicting climate change impact on ecosystem structure and services is one of the most important challenges in ecology. Until now, plant species response to climate change has been described at the level of fixed plant functional types, an approach limited by its inflexibility as there is much interspecific functional variation within plant functional types. Considering a plant species as a set of functional traits greatly increases our possibilities for analysis of ecosystem functioning and carbon and nutrient fluxes associated therewith. Moreover, recently assembled large-scale databases hold comprehensive per-species data on plant functional traits, allowing a detailed functional description of many plant communities on Earth. Here, we show that plant functional traits can be used as predictors of vegetation response to climate warming, accounting in our test ecosystem (the species-rich alpine belt of Caucasus mountains, Russia) for 59% of variability in the per-species abundance relation to temperature. In this mountain belt, traits that promote conservative leaf water economy (higher leaf mass per area, thicker leaves) and large investments in belowground reserves to support next year’s shoot buds (root carbon content) were the best predictors of the species increase in abundance along with temperature increase. This finding demonstrates that plant functional traits constitute a highly useful concept for forecasting changes in plant communities, and their associated ecosystem services, in response to climate change. PMID:24145400

Soudzilovskaia, Nadejda A.; Elumeeva, Tatiana G.; Onipchenko, Vladimir G.; Shidakov, Islam I.; Salpagarova, Fatima S.; Khubiev, Anzor B.; Tekeev, Dzhamal K.; Cornelissen, Johannes H. C.

2013-01-01

258

Spatial heterogeneity in the timing of birch budburst in response to future climate warming in Ireland  

NASA Astrophysics Data System (ADS)

In order to predict the impact of future climate warming on trees it is important to quantify the effect climate has on their development. Our understanding of the phenological response to environmental drivers has given rise to various mathematical models of the annual growth cycle of plants. These models simulate the timing of phenophases by quantifying the relationship between development and its triggers, typically temperature. In addition, other environmental variables have an important role in determining the timing of budburst. For example, photoperiod has been shown to have a strong influence on phenological events of a number of tree species, including Betula pubescens (birch). A recently developed model for birch (DORMPHOT), which integrates the effects of temperature and photoperiod on budburst, was applied to future temperature projections from a 19-member ensemble of regional climate simulations (on a 25 km grid) generated as part of the ENSEMBLES project, to simulate the timing of birch budburst in Ireland each year up to the end of the present century. Gridded temperature time series data from the climate simulations were used as input to the DORMPHOT model to simulate future budburst timing. The results showed an advancing trend in the timing of birch budburst over most regions in Ireland up to 2100. Interestingly, this trend appeared greater in the northeast of the country than in the southwest, where budburst is currently relatively early. These results could have implications for future forest planning, species distribution modeling, and the birch allergy season.

Caffarra, Amelia; Zottele, Fabio; Gleeson, Emily; Donnelly, Alison

2014-05-01

259

Spatial heterogeneity in the timing of birch budburst in response to future climate warming in Ireland.  

PubMed

In order to predict the impact of future climate warming on trees it is important to quantify the effect climate has on their development. Our understanding of the phenological response to environmental drivers has given rise to various mathematical models of the annual growth cycle of plants. These models simulate the timing of phenophases by quantifying the relationship between development and its triggers, typically temperature. In addition, other environmental variables have an important role in determining the timing of budburst. For example, photoperiod has been shown to have a strong influence on phenological events of a number of tree species, including Betula pubescens (birch). A recently developed model for birch (DORMPHOT), which integrates the effects of temperature and photoperiod on budburst, was applied to future temperature projections from a 19-member ensemble of regional climate simulations (on a 25 km grid) generated as part of the ENSEMBLES project, to simulate the timing of birch budburst in Ireland each year up to the end of the present century. Gridded temperature time series data from the climate simulations were used as input to the DORMPHOT model to simulate future budburst timing. The results showed an advancing trend in the timing of birch budburst over most regions in Ireland up to 2100. Interestingly, this trend appeared greater in the northeast of the country than in the southwest, where budburst is currently relatively early. These results could have implications for future forest planning, species distribution modeling, and the birch allergy season. PMID:24037345

Caffarra, Amelia; Zottele, Fabio; Gleeson, Emily; Donnelly, Alison

2014-05-01

260

Effect of climatic warming on the Pacific walrus, and potential modification of its helminth fauna.  

PubMed

The decreasing extent of sea-ice in the arctic basin as a consequence of climatic warming is modifying the behavior and diets of pagophilic pinnipeds, including the Pacific walrus, Odobenus rosmarus divergens Illiger, the species emphasized here. Mammals such as the walrus and bearded seal, Erignathus barbatus (Erxleben), cannot remain associated with the sea-ice, and continue to feed on their usual diet of benthic invertebrates inhabiting coastal waters to a depth of approximately 100 m, when the northwestward retreating ice reaches deep waters beyond the margins of the continental shelf. With reduction of their customary substrate (ice), the walrus has become more pelagic and preys more often on ringed seals, Phoca hispida Schreber. Dietary changes, with modifications of helminth faunas, may be induced by various factors. Increased consumption of mammals or their remains by walruses may lead to a higher prevalence of trichinellosis in them and to more frequent occurrence in indigenous peoples inhabiting the arctic coasts. To assess predicted effects on the composition of helminth fauna of the walrus, we recommend systematic surveys of their helminths as part of research on effects of climatic warming. PMID:18163371

Rausch, Robert L; George, John C; Brower, Harry K

2007-10-01

261

Climate warming during Antarctic ice sheet expansion at the Middle Miocene transition  

NASA Astrophysics Data System (ADS)

During the Middle Miocene climate transition about 14 million years ago, the Antarctic ice sheet expanded to near-modern volume. Surprisingly, this ice sheet growth was accompanied by a warming in the surface waters of the Southern Ocean, whereas a slight deep-water temperature increase was delayed by more than 200 thousand years. Here we use a coupled atmosphere-ocean model to assess the relative effects of changes in atmospheric CO2 concentration and ice sheet growth on regional and global temperatures. In the simulations, changes in the wind field associated with the growth of the ice sheet induce changes in ocean circulation, deep-water formation and sea-ice cover that result in sea surface warming and deep-water cooling in large swaths of the Atlantic and Indian ocean sectors of the Southern Ocean. We interpret these changes as the dominant ocean surface response to a 100-thousand-year phase of massive ice growth in Antarctica. A rise in global annual mean temperatures is also seen in response to increased Antarctic ice surface elevation. In contrast, the longer-term surface and deep-water temperature trends are dominated by changes in atmospheric CO2 concentration. We therefore conclude that the climatic and oceanographic impacts of the Miocene expansion of the Antarctic ice sheet are governed by a complex interplay between wind field, ocean circulation and the sea-ice system.

Knorr, Gregor; Lohmann, Gerrit

2014-05-01

262

A Geoclimatic Framework For Characterizing Summer Streamflow Vulnerability To Climate Warming In The Pacific Northwest, USA  

NASA Astrophysics Data System (ADS)

Summer streamflows in Pacific Northwest are largely derived from melting snow and groundwater discharge. As the climate warms, diminishing snowpack and earlier snowmelt will cause spatially non-uniform reductions in summer streamflow. Most assessments of impacts of a changing climate on streamflow make use of downscaled temperature and precipitation projections from General Circulation Models (GCMs). Projected climate simulations from these GCMs are often too coarse for climate change planning purposes, and do not capture smaller scale topographic controls, leading to uncertainty in predicting streamflow. This uncertainty is further amplified when downscaled climate predictions are coupled to macroscale hydrologic models (i.e. Variable Infiltration Capacity (VIC) model) which do not capture the contributions from deep groundwater. Our earlier studies have demonstrated the important role of deep aquifers in mediating streamflow response to climate change, and the need to explicitly incorporate this process into sensitivity assessments. To address this need, we developed and applied an analytical framework for characterizing summer streamflow sensitivity to a change in the timing and magnitude of recharge (rain or snowmelt) in a spatially explicit fashion. Two patterns emerge from this analysis: first, areas with high streamflow sensitivity also have higher summer streamflow. Second, the level of sensitivity and spatial extent of highly sensitive areas diminishes over time as the summer progresses. Results of this analysis point to a robust, practical, and scalable approach that can help prioritize risk at the landscape scale, complement the downscaling approach, and provide a framework to assist land and water managers adapt to an uncertain and risky future.

Grant, G. E.; Safeeq, M.; Staab, B. P.; Kramer, M.

2012-12-01

263

Recent rapid warming of the Antarctic Peninsula set in context with regional Holocene climate records (Invited)  

NASA Astrophysics Data System (ADS)

The Antarctic Peninsula is one of the most rapidly warming regions on Earth, with historical observations from local meteorological stations documenting warming equivalent to around 3.5°C per century. During recent decades ice shelves to the north-east of Antarctic Peninsula have been lost, causing an acceleration of the feeder glaciers that drain ice from the Antarctic Peninsula. However, marine sediment records taken from beneath the former Prince Gustav Channel and Larsen B ice shelves suggest that they were also absent during the middle of the Holocene, presumably before then being re-established, and then lost again recently. The paradox between modern observations of rapid climate change and retreating ice shelves, and yet an apparent absence of those same ice shelves only a few thousand years before today, cries out for a local paleoclimate record. This was achieved by a joint UK-French team who recovered an ice core to bedrock in 2008 from James Ross Island, situated at the north of the Antarctic Peninsula, close to the area where ice shelves have retreated. The 364m long core spans the whole of the period from the Last Glacial Maximum through to the present. Our temperature estimates, based on the record of water deuterium isotope variations in the ice, show that the northern Antarctic Peninsula experienced an early-Holocene climate optimum about 1.3°C warmer than present, followed by cooler stable temperatures, from about 9,200 to 2,500 years ago, that were similar to the modern-day levels. We find that the late Holocene development of ice shelves near James Ross Island was coincident with pronounced cooling from 2,500 to 600 years ago. Warming of the northern Antarctic Peninsula began around 600 years ago, with the rate becoming more rapid during the 20th century. We discuss the temperature record from the James Ross Island ice core together with other paleoclimate references from this region.

Mulvaney, R.; Abram, N.; Arrowsmith, C.

2013-12-01

264

Does climate warming stimulate or inhibit soil protist communities? A test on testate amoebae in high-arctic tundra with free-air temperature increase.  

PubMed

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. PMID:20708962

Tsyganov, Andrey N; Nijs, Ivan; Beyens, Louis

2011-04-01

265

6146 JOURNAL OF CLIMATE VOLUME 24 Response of the Indian Ocean Basin Mode and Its Capacitor Effect to Global Warming*  

E-print Network

The development of the Indian Ocean basin (IOB) mode and its change under global warming are investigated using a pair of integrations with the Geophysical Fluid Dynamics Laboratory Climate Model version 2.1 (CM2.1). In the simulation under constant climate forcing, the El Niño–induced warming over the tropical Indian Ocean (TIO) and its capacitor effect on summer northwest Pacific climate are reproduced realistically. In the simulation forced by increased greenhouse gas concentrations, the IOB mode and its summer capacitor effect are enhanced in persistence following El Niño, even though the ENSO itself weakens in response to global warming. In the prior spring, an antisymmetric pattern of rainfall–wind anomalies and the meridional SST gradient across the equator strengthen via increased wind–evaporation–sea surface temperature (WES) feedback. ENSO decays slightly faster in global warming. During the summer following El Niño decay, the resultant decrease in equatorial Pacific SST strengthens the SST contrast with the enhanced TIO warming, increasing the sea level pressure gradient and intensifying the anomalous anticyclone over the northwest Pacific. The easterly wind anomalies associated with the northwest Pacific anticyclone in turn sustain the SST warming over the north Indian Ocean and South China Sea. Thus, the increased TIO capacitor effect is due to enhanced air–sea interaction over the TIO and with the western Pacific. The implications for the observed intensification of the IOB mode and its capacitor effect after the 1970s are discussed. 1.

Xiao-tong Zheng; Shang-ping Xie; Qinyu Liu

2010-01-01

266

BVOCs emission in a semi-arid grassland under climate warming and nitrogen deposition  

NASA Astrophysics Data System (ADS)

Biogenic volatile organic compounds (BVOCs) profoundly affect atmospheric chemistry and ecosystem functioning. BVOCs emission and their responses to global change are still unclear in grasslands, which cover one quarter of the Earth's land surface and are currently undergoing the largest changes. Over two growing seasons, we conducted a field experiment in a semi-arid grassland (Inner Mongolia, China) to examine the emission and the responses of BVOCs emissions to warming and nitrogen deposition. The natural emission rate (NER) of monoterpene (dominant BVOCs here) is 107 ± 16 ?g m-2 h-1 in drought 2007, and 266 ± 53 ?g m-2 h-1 in wet 2008, respectively. Warming decreased the standard emission factor (SEF) by 24% in 2007, while it increased by 43% in 2008. The exacerbated soil moisture loss caused by warming in dry season might be responsible for the decrease of SEF in 2007. A possible threshold of soil moisture (8.2% (v/v)), which controls the direction of warming effects on monoterpene emission, existed in the semiarid grassland. Nitrogen deposition decreased the coverage of Artemisia frigida and hence reduced the NER by 24% across the two growing seasons. These results suggest that the grasslands dominated by the extended Artemisia frigida are an important source for BVOCs, while the responses of their emissions to global changes are more uncertain since they depend on multifactorial in-situ conditions.

Wang, H. J.; Xia, J. Y.; Mu, Y. J.; Nie, L.; Han, X. G.; Wan, S. Q.

2012-04-01

267

BVOCs emission in a semi-arid grassland under climate warming and nitrogen deposition  

NASA Astrophysics Data System (ADS)

Biogenic volatile organic compounds (BVOCs) profoundly affect atmospheric chemistry and ecosystem functioning. BVOCs emission and their responses to global change are still unclear in grasslands, which cover one quarter of the Earth's land surface and are currently undergoing the largest changes. Over two growing seasons, we conducted a field experiment in a semi-arid grassland (Inner Mongolia, China) to examine the emission and the responses of BVOCs emissions to warming and nitrogen deposition. The natural emission rate (NER) of monoterpene (dominant BVOCs here) is 107 ± 16 ?g m-2 h-1 in drought 2007, and 266 ± 53 ?g m-2 h-1 in wet 2008, respectively. Warming decreased the standard emission factor (SEF) by 24% in 2007, while increased it by 43% in 2008. The exacerbated soil moisture loss caused by warming in dry season might be responsible for the decrease of SEF in 2007. A possible threshold of soil moisture (8.2% (v/v)), which controls the direction of warming effects on monoterpene emission, existed in the semiarid grassland. Nitrogen deposition decreased the coverage of Artemisia frigida and hence reduced the NER by 24% across the two growing seasons. These results suggest that the grasslands dominated by the extended Artemisia frigida are an important source for BVOCs, while the responses of their emissions to global changes are more uncertain since they depend on multifactorial/in-situ/conditions.

Wang, H. J.; Xia, J. Y.; Mu, Y. J.; Nie, L.; Han, X. G.; Wan, S. Q.

2012-01-01

268

Climate hotspots: key vulnerable regions, climate change and limits to warming  

Microsoft Academic Search

Defining and operationalizing Article 2 of the UNFCCC remains a challenge. The question of what is dangerous climate change\\u000a is not a purely scientific one, as danger necessarily has a subjective dimension and its definition requires judgment and\\u000a precaution. The papers in this special issue of Regional Environmental Change attempt to navigate this problem, by offering\\u000a an overview of the

William L. Hare; Wolfgang Cramer; Michiel Schaeffer; Antonella Battaglini; Carlo C. Jaeger

2011-01-01

269

Is the impact of future climate change on hydro-climatic conditions significant? - A climate change study for an Eastern European catchment area.  

NASA Astrophysics Data System (ADS)

The future change of climatic conditions is, among others, closely linked to future hydrological changes. One important aspect of these issues is the question of future availability of water resources. A changed climatic water balance, as indicator for potential water availability, has far-reaching consequences for the water cycle, hydrological conditions, ecology, water management, the energy business, agriculture and forestry, and for anthropogenic use of the river. We generated regional climate projections via dynamic downscaling for the catchment area of the Western Bug river in the border area of Poland, Belarus, and Ukraine. The hydro-climatic conditions of the past and their projected future changes in the catchment were analyzed based on 2m-temperature, precipitation, potential evaporation and climatic water balance. Up to the end of the century, the used IPCC scenarios B1 and A2 lead to warming for each month in the long-term mean, with highest warming rates in winter. Instead, precipitation does not change in the long-term yearly mean. However, the intra-annual distribution of monthly precipitation sums shifts with an increase in winter and a strong decrease in summer. Combined, this leads to a changed climatic water balance with a stronger deficit in summer and a higher gain in winter. Particular in the south-eastern part of the catchment, the summer deficit cannot be compensated within the annual cycle. It raised the question: are these changes statistically significant and thus robust for use in further impact studies? Using a significance analysis, we found, that climatic changes in temperature, precipitation and potential evaporation and thus the climatic water balance change is most significant for scenario A2 from 2071 to 2100. The temperature changes are significant throughout the year. For the other variables changes are most significant in the late summer months (July, August, and September) and the winter months (December, January, and February). In contrast, projected changes are hardly significant in the first period from 2021 to 2050. Only temperatures show most statistically significant changes. Weaker change signals in temperature, precipitation and potential evaporation lead also to weak climatic water balance changes in the first period. However, the projected changes in the first period are already indications of impending climatic changes in the catchment.

Pavlik, Dirk; Söhl, Dennis; Bernhofer, Christian

2014-05-01

270

Tropical Cyclone Climatology in a Global-Warming Climate as Simulated in a 20 km-Mesh Global Atmospheric Model: Frequency and Wind Intensity Analyses  

Microsoft Academic Search

Possible changes in the tropical cyclones in a future, greenhouse-warmed climate are investigated using a 20 km-mesh, high-resolution, global atmospheric model of MRI\\/JMA, with the analyses focused on the evaluation of the frequency and wind intensity. Two types of 10-year climate experiments are conducted. One is a present-day climate experiment, and the other is a greenhouse-warmed climate experiment, with a

Kazuyoshi OOUCHI; Jun YOSHIMURA; Hiromasa YOSHIMURA; Ryo MIZUTA; Shoji KUSUNOKI; Akira NODA

2006-01-01

271

Thermokarst processes in west-European loess series: new evidences for rapid climatic warming events during the Last Glacial  

NASA Astrophysics Data System (ADS)

For a long time, the imprint of millennial climatic cycles (D/O cycles) in the Last Glacial loess sequences has been related to the alternation of loess layers and arctic brown soil horizons, especially between about 60 and 30 ka BP (± MIS 3). Nevertheless, owing to erosion gaps and strong reductions in the sedimentation rate, there are always less individual soil horizons than D/O cycles during the same period, which makes correlations very difficult. The discovery in the Nussloch loess sequence (Germany) of a thermokarst structure including well preserved vegetal remains, mollusc shells, and relicts of former ice wedge casts, provides new evidences for a rapid climatic warming at the origin of a major erosion event during the Middle Pleniglacial (±MIS 3). This elongated thermokarst erosion gully incised the underlying deposits. The presence of deformed ice-wedge relicts along its very sharp and irregular lower boundary indicates a formation by thermal erosion linked to a rapid melting of the permafrost ice. The analysis of the biological data (vegetal remains and mollusc shells) allows to evidence interstadial conditions strongly contrasting with the over- and underlying loess environments. Radiocarbon dates from wood remains (average 32.26 14C / ± 37.7 cal. BP) allow the correlation of the main thermokarst formation and infilling with GIS-8 from the GRIP ice core, following H4 event. Similar structures have been evidenced in other west-European loess sequences, most of them at the base of the Middle Pleniglacial formations. On the basis of a comparison with present day analogues from Alaska and Siberia permafrost areas, past "thermokarst events" are related to thermal erosion processes and proposed as markers for rapid warming periods in Last Glacial European loess sequences.

Antoine, Pierre; Moine, Olivier; Didier Rousseau, Denis; Hatté, Christine

2013-04-01

272

Impact of global warming on the geobotanic zones: an experiment with a statistical-dynamical climate model  

NASA Astrophysics Data System (ADS)

In this study, a zonally-averaged statistical climate model (SDM) is used to investigate the impact of global warming on the distribution of the geobotanic zones over the globe. The model includes a parameterization of the biogeophysical feedback mechanism that links the state of surface to the atmosphere (a bidirectional interaction between vegetation and climate). In the control experiment (simulation of the present-day climate) the geobotanic state is well simulated by the model, so that the distribution of the geobotanic zones over the globe shows a very good agreement with the observed ones. The impact of global warming on the distribution of the geobotanic zones is investigated considering the increase of CO2 concentration for the B1, A2 and A1FI scenarios. The results showed that the geobotanic zones over the entire earth can be modified in future due to global warming. Expansion of subtropical desert and semi-desert zones in the Northern and Southern Hemispheres, retreat of glaciers and sea-ice, with the Arctic region being particularly affected and a reduction of the tropical rainforest and boreal forest can occur due to the increase of the greenhouse gases concentration. The effects were more pronounced in the A1FI and A2 scenarios compared with the B1 scenario. The SDM results confirm IPCC AR4 projections of future climate and are consistent with simulations of more complex GCMs, reinforcing the necessity of the mitigation of climate change associated to global warming.

Franchito, Sergio H.; Brahmananda Rao, V.; Moraes, E. C.

2011-11-01

273

Greenhouse to icehouse: Understanding the role of CO2 and non-CO2 forcings in warm climate intervals  

NASA Astrophysics Data System (ADS)

The Earth system has evolved significantly over the past 65 million years. A relatively ice free world dominated the Eocene ˜45 million years ago (Ma), until the late Oligocene (˜34 Ma) when the Antarctic Ice Sheet (AIS) developed in relatively short time period. Throughout the Oligocene and Miocene (23 to 5.3 Ma) temperatures gradually decreased as atmospheric CO2 continued to fall, vegetation biomes shifted, ocean circulation moved into its modern positions, and ocean gateways opened and closed. This transition from the warm and humid Eocene climate to the icehouse world we currently live has largely been attributed to a gradual decline in atmospheric CO 2. Acknowledging the fact that CO2 was the dominant driver in the gradual cooling over the last 65 million years, here we explore the less constrained feedbacks and forcings within the Earth system. These non-CO 2 forcings are important and could prove pivotal as we continue to constrain future climate prediction. Here we explore the climatic impact and forcing of the AIS, the oceanic response to AIS forcing, the temperature and precipitation patterns induced by changes in the El Nino southern Oscillation, and the impacts of El Nino and AIS forcing in the mid-Miocene Climatic Optimum (MMCO). Specifically, we find that the distribution of sea surface temperature (SSTs) in the eastern equatorial pacific has a teleconnected fingerprint throughout the world and more El Nino like conditions is a possible explanation of the wetter conditions in the mid-latitudes during the Pliocene and Miocene. The effective forcing and temperature impact of the Antarctic Ice Sheet depends on the mean climate state as modern climate responds differently to removing the AIS than at the Eocene-Oligocene transition and during the MMCO. The differing temperature and climate sensitivity response is largely controlled by low cloud and sea-ice feedbacks during these time periods and the efficacy of AIS forcing in the Eocene is not necessarily close to one and is likely to be model and state dependent. We also find that adding the AIS into the unglaciated Eocene world cools the deep ocean comparable to previous modelling studies that opened southern ocean gateways. The modelled delta18O anomaly induced by glaciation is comparable to the change detected in the proxy records across the transition suggesting that the AIS can induce changes in ocean circulation and thermal structure, thus reversing the hypothesis that gateways caused a reorganization of ocean circulation and glaciation across the EOT. Finally, Simulating the MMCO at 400 ppm CO2 using a recently released state of the art modelling framework produces a model data mismatch in global MAT and at high latitudes. The discrepancy is comparable to that introduced by a full doubling of CO2. It is noteworthy that including two of the most discussed Earth system feedbacks (El Nino and reduced ice volume) had small impacts on improving the model predictions even when we included uncertainty from orbital forcing. In summary, the Earth system is complex and explaining the warmth in past greenhouse climates requires many changes to boundary conditions, the right climate modelling framework, and better understanding of the non-CO 2 climate forcings.

Goldner, Aaron P.

274

The palaeoclimatic significance of Eurasian Giant Salamanders (Cryptobranchidae: Zaissanurus, Andrias) - indications for elevated humidity in Central Asia during global warm periods (Eocene, late Oligocene warming, Miocene Climate Optimum)  

NASA Astrophysics Data System (ADS)

Cryptobranchids represent a group of large sized (up to 1.8 m) tailed amphibians known since the Middle Jurassic (Gao & Shubin 2003). Two species are living today in eastern Eurasia: Andrias davidianus (China) and A. japonicus (Japan). Cenozoic Eurasian fossil giant salamanders are known with two genera and two or three species from over 30 localities, ranging from the Late Eocene to the Early Pliocene (Böhme & Ilg 2003). The Late Eocene species Zaissanurus beliajevae is restricted to the Central Asian Zaissan Basin (SE-Kazakhstan, 50°N, 85°E), whereas the Late Oligocene to Early Pliocene species Andrias scheuchzeri is distributed from Central Europe to the Zaissan Basin. In the latter basin the species occur during two periods; the latest Oligocene and the late Early to early Middle Miocene (Chkhikvadse 1982). Andrias scheuchzeri is osteological indistinguishable from both recent species, indicating a similar ecology (Westfahl 1958). To investigate the palaeoclimatic significance of giant salamanders we analyzed the climate within the present-day distribution area and at selected fossil localities with independent palaeoclimate record. Our results indicate that fossil and recent Andrias species occur in humid areas where the mean annual precipitation reach over 900 mm (900 - 1.300 mm). As a working hypothesis (assuming a similar ecology of Andrias and Zaissanurus) we interpret occurrences of both fossil Eurasian giant salamanders as indicative for humid palaeoclimatic conditions. Based on this assumption the Late Eocene, the latest Oligocene (late Oligocene warming) and the late Early to early Middle Miocene (Miocene Climatic Optimum) of Central Asia (Zaissan Basin) are periods of elevated humidity, suggesting a direct (positive) relationship between global climate and Central Asian humidity evolution. Böhme M., Ilg A. 2003: fosFARbase, www.wahre-staerke.com/ Chkhikvadze V.M. 1982. On the finding of fossil Cryptobranchidae in the USSR and Mongolia. Vertebrata Hungarica, 21: 63-67. Gao K.-Q., Shubin N.H. 2003. Earliest known crown-group Salamanders. Nature, 422: 424-428. Westphal F. 1958. Die Tertiären und rezenten Eurasiatischen Riesensalamander. Palaeontolographica Abt. A, 110: 20-92.

Vasilyan, Davit; Böhme, Madelaine; Winklhofer, Michael

2010-05-01

275

Zonobiomes, forests, and major forest-forming conifers across Northern Eurasia by the end of the century under climate warming  

NASA Astrophysics Data System (ADS)

Simulations of terrestrial ecosystems demonstrated globally the profound effects of the GCM-predicted climate change on their distribution at all hierarchical levels: zonobiomes, forests, and forest-forming tree species. We investigated progressions of potential vegetation cover, forest cover and ranges of forest-forming conifers across Northern Eurasia and Russia in the warming climate during the current century. We developed envelope-type static large-scale bioclimatic models predicting zonobiomes NEBioCliM, forests (ForCliM) and primary forest-forming conifer trees (TreeCliM)) from three bioclimatic indices (1) growing degree-days above 5oC, GDD5; (2) negative degree-days below 0oC, NDDo; and (3) an annual moisture index (ratio of growing degree days above 5oC to annual precipitation), AMI. No soil conditions except presence/absence of permafrost were taken into account in our models. Continuous permafrost was included in the models as limiting the forests and tree species distribution in interior Siberia. Each zonobiome, forest type and conifer distribution was mapped for the basic period 1960-1990 and for 2080 by coupling our bioclimatic models with bioclimatic indices and the permafrost distribution for the 1960-1990 and 2080 simulations. Climatic departures for the 2080 climate were derived from two climate change scenarios, the HadCM3 A2 and B1 (IPCC, 2007). Kappa (K) statistics were used to compare both the modeled vegetation and the conifer distributions in the contemporary climate to actual vegetation and forest maps. K-statistics proved that NEBioCliM accomplished a fair work in modeling zonobiomes across Russia. The tree species distributions also showed good match with the modeled ranges: 41% (Abies sibirica), 46% (Pinus sibirica), 71% (Pinus sylvestris), 75% (Picea spp.) and 78% (Larix spp.). Those matches might be higher because historically part of the primary conifer forests were replaced by secondary birch and aspen forests after large disturbances (clearcuts and wildfire). With these projected climates, the zonobiomes would need to shift far to the north in order to reach an equilibrium with the change in climate. Because future climate is predicted to be much warmer and drier, the future climate would be suitable for the forest-steppe ecotone and grasslands (up to 80%) rather than forests (less than 20%). Water stress tolerant light-needled taiga would have advantage over water-loving dark-needled taiga in a new climate. Permafrost wiould not retreat fast enough to make favorable habitats for dark taiga and L. dahurica taiga withstanding permafrost would remain the dominant forest type. Accumulated fire load due to increased tree mortality, especially at the southern forest border and in interior Siberia (Yakutia), together with an increase in fire weather would also initiate large fires facilitating vegetation progression towards an equilibrium with the climate.

Tchebakova, N.; Parfenova, E. I.; Shvetsov, E.; Soja, A. J.; Conard, S. G.

2012-12-01

276

Stable climate and surface mass balance in Svalbard over 1979-2013 despite the Arctic warming  

NASA Astrophysics Data System (ADS)

With the help of the regional climate model MAR (Modèle Atmosphérique Régional) forced by the ERA-Interim reanalysis (MARERA) and the MIROC5 (Model for Interdisciplinary Research on Climate) global model (MARMIROC5) from the CMIP5 (Coupled Model Intercomparison Project) database, we have modelled the climate and surface mass balance of Svalbard at a 10 km resolution over 1979-2013. The integrated total surface mass balance (SMB) over Svalbard modelled by MARERA is negative (-1.6 Gt yr-1) with a large interannual variability (7.1 Gt) but, unlike over Greenland, there has been no acceleration of the surface melt over the past 35 years because of the recent change in atmospheric circulation bringing northwesterly flows in summer over Svalbard, contrasting the recent observed Arctic warming. However, in 2013, the atmospheric circulation changed to a south-southwesterly flow over Svalbard causing record melt, SMB (-20.4 Gt yr-1) and summer temperature. MIROC5 is significantly colder than ERA-Interim over 1980-2005 but MARMIROC5 is able to improve the near-surface MIROC5 results by simulating not significant SMB differences with MARERA over 1980-2005. On the other hand, MIROC5 does not represent the recent atmospheric circulation shift in summer and induces in MARMIROC5 a significant trend of decreasing SMB (-0.6 Gt yr-2) over 1980-2005.

Lang, C.; Fettweis, X.; Erpicum, M.

2015-01-01

277

Temporal trends of mercury in Greenland ringed seal populations in a warming climate.  

PubMed

Temporal trends of mercury in livers of ringed seals collected from the early 1980s to 2010 from central West, Northwest and central East Greenland were studied. In this period the climate of Greenland warmed and the influences of climate indices such as ice coverage, water temperature and the Atlantic Oscillation Index on mercury concentration were evaluated using multiple regressions and Akaike's Information Criteria (AIC) to determine the most parsimonious models. Biological co-variables such as age, sex and trophic position (as determined by stable isotope analysis) of seals were also evaluated. Increasing levels of mercury in seals were found in Ittoqqortoormiit, central East Greenland, and Avanersuaq, Northwest Greenland, with an annual increase of +10.3 and +2%, respectively. Age was an important co-variable for all three regions and trophic position for two regions. The Atlantic Oscillation Index was also an important explanatory variable for all three regions and was positively associated with mercury concentrations in seals indicating the importance of global climatic processes on ringed seal populations in Greenland. PMID:23152143

Rigét, Frank; Dietz, Rune; Hobson, Keith A

2012-12-01

278

Altitudinal and latitudinal dependence of future warming in an island of multi climate zones: Taiwan as an example  

NASA Astrophysics Data System (ADS)

In this study, a global model, ECHAM5, and a mesoscale regional model, Weather Research Forecasting (WRF) were combined to perform dynamic downscaling of Taiwan's climate in the recent past (1979-2003) and climate change projection of near and distant future (2015-2039 and 2075-2099, respectively). Simulation results showed close correlation between fine-resolution downscaling by ECHAM5-WRF and the actual observation data for the period 1979-2003. Projection of future climate changes revealed both altitudinal and latitudinal variations in warming trend, with more significant temperature increase in mountain areas than in plain areas toward the end of the 21st century and more obvious warming in the north than in the south of Taiwan. These findings have essential implications on climate impact issues such as mountain ecology and disease transmission. The results obtained in this study can be applied to other regions of similar latitudes and with comparable relief.

Lin, Chuan-yao; Chua, Ying-Jea; sheng, Yang-Fan; Hsu, Huang-Hsiung; Cheng, Chao-Tzuen; Lin, Yi-Yin

2014-05-01

279

Diagnosing Warm Frontal Cloud Formation in a GCM: A Novel Approach Using Conditional Subsetting  

NASA Technical Reports Server (NTRS)

This study analyzes characteristics of clouds and vertical motion across extratropical cyclone warm fronts in the NASA Goddard Institute for Space Studies general circulation model. The validity of the modeled clouds is assessed using a combination of satellite observations from CloudSat, Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E), and the NASA Modern-Era Retrospective Analysis for Research and Applications (MERRA) reanalysis. The analysis focuses on developing cyclones, to test the model's ability to generate their initial structure. To begin, the extratropical cyclones and their warm fronts are objectively identified and cyclone-local fields are mapped into a vertical transect centered on the surface warm front. To further isolate specific physics, the cyclones are separated using conditional subsetting based on additional cyclone-local variables, and the differences between the subset means are analyzed. Conditional subsets are created based on 1) the transect clouds and 2) vertical motion; 3) the strength of the temperature gradient along the warm front, as well as the storm-local 4) wind speed and 5) precipitable water (PW). The analysis shows that the model does not generate enough frontal cloud, especially at low altitude. The subsetting results reveal that, compared to the observations, the model exhibits a decoupling between cloud formation at high and low altitudes across warm fronts and a weak sensitivity to moisture. These issues are caused in part by the parameterized convection and assumptions in the stratiform cloud scheme that are valid in the subtropics. On the other hand, the model generates proper covariability of low-altitude vertical motion and cloud at the warm front and a joint dependence of cloudiness on wind and PW.

Booth, James F.; Naud, Catherine M.; DelGenio, Anthony D.

2013-01-01

280

Comparing Effects of Climate Warming, Fire, and Timber Harvesting on a Boreal Forest Landscape in Northeastern China  

PubMed Central

Forest management under a changing climate requires assessing the effects of climate warming and disturbance on the composition, age structure, and spatial patterns of tree species. We investigated these effects on a boreal forest in northeastern China using a factorial experimental design and simulation modeling. We used a spatially explicit forest landscape model (LANDIS) to evaluate the effects of three independent variables: climate (current and expected future), fire regime (current and increased fire), and timber harvesting (no harvest and legal harvest). Simulations indicate that this forested landscape would be significantly impacted under a changing climate. Climate warming would significantly increase the abundance of most trees, especially broadleaf species (aspen, poplar, and willow). However, climate warming would have less impact on the abundance of conifers, diversity of forest age structure, and variation in spatial landscape structure than burning and harvesting. Burning was the predominant influence in the abundance of conifers except larch and the abundance of trees in mid-stage. Harvesting impacts were greatest for the abundance of larch and birch, and the abundance of trees during establishment stage (1–40 years), early stage (41–80 years) and old- growth stage (>180 years). Disturbance by timber harvesting and burning may significantly alter forest ecosystem dynamics by increasing forest fragmentation and decreasing forest diversity. Results from the simulations provide insight into the long term management of this boreal forest. PMID:23573209

Li, Xiaona; He, Hong S.; Wu, Zhiwei; Liang, Yu; Schneiderman, Jeffrey E.

2013-01-01

281

Biotic Response in Aquatic Reptiles (Testudines) during Earliest Eocene Climatic Warming  

NASA Astrophysics Data System (ADS)

The earliest Eocene is marked by significant events of global warming: the Paleocene-Eocene Thermal Maximum (PETM) at ~55.8 Ma and two short-lived events (ETM2 or Elmo and H2) approximately 2 Ma later. These environmental changes induced strong responses in the continental biota. Noteworthy changes in North American mid-latitude faunas and floras that are temporally correlated with earliest Eocene warming events include: increased diversity; turnover; and significant range changes, comprising both northward shifts in ranges of North American taxa as well as intercontinental dispersal across Holarctica. Evidence for these biotic changes comes directly from the fossil record and indirectly from phylogeographic analyses of molecular phylogenies of extant biota. To date, the stratigraphic record of biotic change has only been examined for the flora and terrestrial mammals. Data on reptiles and for continental aquatic systems are particularly lacking. In order to assess the impact of climate-mediated faunal change in aquatic systems during early Paleogene warming, we have focused on developing a detailed record of fossil turtles (Testudines) from the Bighorn Basin of Wyoming, where these records can be directly compared to similarly studied mammalian and floral data and to isotopic studies that provide independent proxies of climate change. Using genus-level occurrence data from more than 450 stratigraphically-constrained localities spanning ~2.5 Ma, we calculated first and last appearances, taxonomic richness, and relative abundance as measured by presence-absence (site occupancy). Among turtles, taxonomic richness increased episodically through the earliest Eocene with two new taxa appearing at the PETM, two immediately following it, and two at Biohorizon B, an interval associated with the younger hyperthermals. These new, immigrant taxa eventually comprised 40% of known generic richness. Phylogenetically, the inferred biogeographic source regions are southern North America and Asia, with an equal number of taxa originating in each area. Although immigrant taxa comprised less than half of the known earliest Eocene diversity, their relative dominance in these assemblages varied markedly. Within the PETM interval, immigrant taxa comprise nearly 70% of occurrences. Post-PETM, as temperatures cooled, immigrant taxa and taxa persisting from the Paleocene showed greater evenness, but immigrant taxa again became dominant with renewed warming. Among immigrant taxa, intercontinental dispersers are much more common than those that that dispersed from southern North America. These data are consistent with and stratigraphically correlative with significant changes in the mammalian fauna and flora of the Bighorn Basin and underline the importance of climatic change as a driver in these events. However, the magnitude and relative importance of intra- vs. intercontinental dispersal has not yet been fully examined in other taxonomic groups. The asymmetry of response following immigration that we observe in turtles may be taxon-specific, unique to aquatic systems, or may illustrate a more general pattern of how biotas respond to significant climate change.

Holroyd, P. A.; Hutchison, J. H.

2010-12-01

282

The role of climate change and ozone recovery for the future timing of major stratospheric warmings  

NASA Astrophysics Data System (ADS)

Future changes in the occurrence rates of major stratospheric warmings (MSWs) have recently been identified in chemistry-climate model (CCM) simulations, but without reaching a consensus, potentially due to the competition of different forcings. We examine future variations in the occurrence rates of MSWs in transient and timeslice simulations of the ECHAM/MESSy atmospheric chemistry (EMAC) CCM, with a focus on the individual effect of different external factors. Although no statistically significant variation is found in the decadal-mean frequency of MSWs, a shift of their timing toward midwinter is detected in the future. The strengthening of the polar vortex in early winter is explained by recovering ozone levels following the future decrease in ozone-depleting substances. In midwinter, a stronger dynamical forcing associated with changes in tropical sea surface temperatures will lead to more MSWs, through a similar mechanism that explains the stratospheric response to El Niño-Southern Oscillation (ENSO).

Ayarzagüena, Blanca; Langematz, Ulrike; Meul, Stefanie; OberläNder, Sophie; Abalichin, Janna; Kubin, Anne

2013-05-01

283

Marine Ecosystem Response to Rapid Climate Warming on the West Antarctic Peninsula (Invited)  

NASA Astrophysics Data System (ADS)

The Palmer, Antarctica LTER builds on meteorological, ocean color and seabird observations since the late 1970s. It occupies annually in summer a regional-scale grid extending 700 km northward from Charcot Island to Anvers Island, and 200 km cross-shelf from the coast to the shelfbreak. In addition to routine CTD profiles and zooplankton tows throughout the grid, the observing system also includes Slocum Glider surveys and thermistor moorings. Geophysical changes include +6C atmospheric warming in winter since 1950, a 20% increase in heat content over the continental shelf since 1990, a surface ocean warming of +1C since 1950, an 83-day reduction in sea ice duration (advance 48 days later, retreat 35 days earlier) over the greater southern Bellingshausen Sea region from 1979-2007, intensification of westerly winds and differential changes in cloudiness. In response to these large changes in the regional climate, the marine ecosystem of the western Peninsula is changing at all trophic levels from diatoms to penguins. Ocean color indicates differential changes in phytoplankton stocks in response to regional decreases in sea ice cover. Surface chlorophyll has declined 89% in the north and increased 67% in the south. Antarctic krill and salps have declined and increased in our study area, respectively. Penguin diet sampling suggests changes in populations or distributions of the Antarctic Silverfish in the Anvers Island vicinity, possibly in response to ocean warming. Adélie penguins have declined 75% from 15000 to <3000 pairs at since 1975 in response to changes in food availability and increased late spring snow accumulation. Changes in pygoscelid penguin breeding populations in the Anvers Island vicinity of the West Antarctic Peninsula

Ducklow, H.; Baker, K. S.; Doney, S. C.; Fraser, B.; Martinson, D. G.; Meredith, M. P.; Montes-Hugo, M. A.; Sailley, S.; Schofield, O.; Sherrell, R. M.; Stammerjohn, S. E.; Steinberg, D. K.

2010-12-01

284

Climate warming, marine protected areas and the ocean-scale integrity of coral reef ecosystems.  

PubMed

Coral reefs have emerged as one of the ecosystems most vulnerable to climate variation and change. While the contribution of a warming climate to the loss of live coral cover has been well documented across large spatial and temporal scales, the associated effects on fish have not. Here, we respond to recent and repeated calls to assess the importance of local management in conserving coral reefs in the context of global climate change. Such information is important, as coral reef fish assemblages are the most species dense vertebrate communities on earth, contributing critical ecosystem functions and providing crucial ecosystem services to human societies in tropical countries. Our assessment of the impacts of the 1998 mass bleaching event on coral cover, reef structural complexity, and reef associated fishes spans 7 countries, 66 sites and 26 degrees of latitude in the Indian Ocean. Using Bayesian meta-analysis we show that changes in the size structure, diversity and trophic composition of the reef fish community have followed coral declines. Although the ocean scale integrity of these coral reef ecosystems has been lost, it is positive to see the effects are spatially variable at multiple scales, with impacts and vulnerability affected by geography but not management regime. Existing no-take marine protected areas still support high biomass of fish, however they had no positive affect on the ecosystem response to large-scale disturbance. This suggests a need for future conservation and management efforts to identify and protect regional refugia, which should be integrated into existing management frameworks and combined with policies to improve system-wide resilience to climate variation and change. PMID:18728776

Graham, Nicholas A J; McClanahan, Tim R; MacNeil, M Aaron; Wilson, Shaun K; Polunin, Nicholas V C; Jennings, Simon; Chabanet, Pascale; Clark, Susan; Spalding, Mark D; Letourneur, Yves; Bigot, Lionel; Galzin, René; Ohman, Marcus C; Garpe, Kajsa C; Edwards, Alasdair J; Sheppard, Charles R C

2008-01-01

285

Climate Warming, Marine Protected Areas and the Ocean-Scale Integrity of Coral Reef Ecosystems  

PubMed Central

Coral reefs have emerged as one of the ecosystems most vulnerable to climate variation and change. While the contribution of a warming climate to the loss of live coral cover has been well documented across large spatial and temporal scales, the associated effects on fish have not. Here, we respond to recent and repeated calls to assess the importance of local management in conserving coral reefs in the context of global climate change. Such information is important, as coral reef fish assemblages are the most species dense vertebrate communities on earth, contributing critical ecosystem functions and providing crucial ecosystem services to human societies in tropical countries. Our assessment of the impacts of the 1998 mass bleaching event on coral cover, reef structural complexity, and reef associated fishes spans 7 countries, 66 sites and 26 degrees of latitude in the Indian Ocean. Using Bayesian meta-analysis we show that changes in the size structure, diversity and trophic composition of the reef fish community have followed coral declines. Although the ocean scale integrity of these coral reef ecosystems has been lost, it is positive to see the effects are spatially variable at multiple scales, with impacts and vulnerability affected by geography but not management regime. Existing no-take marine protected areas still support high biomass of fish, however they had no positive affect on the ecosystem response to large-scale disturbance. This suggests a need for future conservation and management efforts to identify and protect regional refugia, which should be integrated into existing management frameworks and combined with policies to improve system-wide resilience to climate variation and change. PMID:18728776

Graham, Nicholas A. J.; McClanahan, Tim R.; MacNeil, M. Aaron; Wilson, Shaun K.; Polunin, Nicholas V. C.; Jennings, Simon; Chabanet, Pascale; Clark, Susan; Spalding, Mark D.; Letourneur, Yves; Bigot, Lionel; Galzin, René; Öhman, Marcus C.; Garpe, Kajsa C.; Edwards, Alasdair J.; Sheppard, Charles R. C.

2008-01-01

286

Differential effects of past climate warming on mountain and flatland species distributions: a multispecies North American mammal assessment  

Microsoft Academic Search

Aim The magnitude of predicted range shifts during climate change is likely to be different for species living in mountainous environments compared with those living in flatland environments. The southern edges of ranges in mountain species may not shift northwards during warming as populations instead migrate up available elevational gradients; overall latitudinal range appears therefore to expand. In contrast, flatland

Robert Guralnick

2006-01-01

287

Possible Effects of Climate Warming on Selected Populations of Polar Bears (Ursus maritimus) in the Canadian Arctic  

Microsoft Academic Search

Polar bears depend on sea ice for survival. Climate warming in the Arctic has caused significant declines in total cover and thickness of sea ice in the polar basin and progressively earlier breakup in some areas. Inuit hunters in the areas of four polar bear populations in the eastern Canadian Arctic (including Western Hudson Bay) have reported seeing more bears

IAN STIRLING; CLAIRE L. PARKINSON

2006-01-01

288

Role of atmospheric adjustments in the tropical Indian Ocean warming during the 20th century in climate models  

E-print Network

simulated by a large ensemble of climate models. In models, changes in net surface heat flux are small-equilibrium adjustments among various surface heat flux components. The warming is triggered by the greenhouse gas such as weakened winds that act to suppress turbulent heat flux from the ocean. The sea surface temperature

Xie, Shang-Ping

289

Global warming feedbacks on terrestrial carbon uptake under the Intergovernmental Panel on Climate Change  

E-print Network

in North America and Eurasia affect ecosystem structure: boreal trees expand poleward in high latitudes forcing is estimated to increase between 3 and 8 W m-2 between now and 2100. Simulated warmer conditions global climate change may affect the world's ecosystems and the services they provide. Carbon dioxide (CO

Fortunat, Joos

290

Global warming and climate change - predictive models for temperate and tropical regions  

SciTech Connect

Based on the assumption of 4{degree}C increase of global temperature by the turn of 21st century due to the accumulation of greenhouse gases an attempt is made to study the possible variations in different climatic regimes. The predictive climatic water balance model for Hokkaido island of Japan (a temperate zone) indicates the possible occurrence of water deficit for two to three months, which is a unknown phenomenon in this region at present. Similarly, India which represents tropical region also will experience much drier climates with increased water deficit conditions. As a consequence, the thermal region of Hokkaido which at present is mostly Tundra and Micro thermal will change into a Meso thermal category. Similarly, the moisture regime which at present supports per humid (A2, A3 and A4) and Humid (B4) climates can support A1, B4, B3, B2 and B1 climates indicating a shift towards drier side of the climatic spectrum. Further, the predictive modes of both the regions have indicated increased evapotranspiration rates. Although there is not much of change in the overall thermal characteristics of the Indian region the moisture regime indicates a clear shift towards the aridity in the country.

Malini, B.H. [Andhra Univ., Visakhapatnam (India)

1997-12-31

291

Conditional Uncertainty in Anthropogenic Global Climate Change  

NASA Astrophysics Data System (ADS)

Although, the uncertainty associated with human-induced climate change is less that in many other human activities such as economic management and warfare, the uncertainties in the climate system have assumed a disproportionate profile in public debate. Achieving improved public understanding is dependent on consistent use of the various categories of change and their respective uncertainties. Probably the most important distinction to be made is between uncertainties associated with uncertain societal choices and uncertainties associated with the consequences of such choices. For the biogeochemical system, categories of uncertainty are adapted from those used in the study of uncertainty for the REgional Carbon Assessment and Processes (RECCAP) study. These are then extended and applied to the discussion of the combined carbon-climate system. Characterising uncertainties in future change requires a consistent approach to propagating into the future the uncertainties associated with the past and present state of the climate system. Again, previous analysis for the carbon system is extended to the carbon-climate system. The potential category ambiguities that arise from feedbacks between climate and carbon are identified and resolved. A consistent characterisation of the uncertainties in the earth system provides a basis for factoring the overall uncertainty into human and natural contributions.

Enting, I. G.

2012-12-01

292

Do variations in the ?13C of soil phospholipid fatty acids indicate changes in substrate use with climate warming?  

NASA Astrophysics Data System (ADS)

The effect of climate warming on the microbial mineralization of soil organic carbon (SOC) remains a key uncertainty in biogeochemical models. In particular, it remains unclear whether microbial substrate use patterns change with climate. The carbon isotopic signature (?13C) of soil microbial phospholipid fatty acids (?13CPLFA) can provide insight into substrate utilization patterns in situ without manipulations unavoidable in soil incubation experiments. The interpretation of ?13CPLFA, however, is limited by gaps in our understanding of the isotopic fractionation associated with PLFA biosynthesis, and in particular, whether this fractionation changes with growth temperature. Characterizing the principles controlling ?13CPLFA under controlled laboratory conditions can help with the interpretation of field measurements of temperature effects on microbial SOC assimilation. We measured ?13CPLFA from field soils in two regions along a boreal climate transect, which differ by 4.5 °C mean annual temperature. In each region, the organic (L, F, H) and mineral (B; top 10cm) soil horizons were sampled at three locations chosen for similar vegetation (balsam fir), stand age, elevation, and soil type (humo-ferric podzol). Soils from both regions had similar bulk SOC ?13C and exhibited an increase with depth from -29.5±0.4 to -26.5±0.6o. Despite the similar ?13C of SOC, PLFA in the organic horizons from the warmer region were more enriched in 13C relative to those from the colder region.In a model that used region, horizon and the individual PLFA as predictors, we found that region had a subtle (0.7o), but highly significant (p

Kohl, Lukas; Laganière, Jérôme; Edwards, Kate; Lehmeier, Christoph; Min, Kyungjin; Billings, Sharon A.; Ballantyne, Ford; Van Biesen, Geert; Morrill, Penny L.; Ziegler, Susan E.

2014-05-01

293

Modelling the climate and ice sheets of the mid-Pliocene warm period: a test of model dependency  

NASA Astrophysics Data System (ADS)

The mid-Pliocene warm period (MPWP; c. 3.0 - 3.3 million years ago) has been the subject of a large number of published studies during the last decade. It is an interval in Earth history, where conditions were similar to those predicted by climate models for the end of the 21st Century. Not only is it important to increase our understanding of the climate dynamics in a warmer world, it is also important to determine exactly how well numerical models can retrodict a climate significantly different from the present day, in order to have confidence in them for predicting the future climate. Previous General Circulation Model (GCM) simulations have indicated that MPWP mean annual surface temperatures were on average 2 to 3?C warmer than the pre-industrial era. Coastal stratigraphy and benthic oxygen isotope records suggest that terrestrial ice volumes were reduced when compared to modern. Ice sheet modelling studies have supported this decrease in cryospheric extent. Generally speaking, both climate and ice sheet modelling studies have only used results from one numerical model when simulating the climate of the MPWP. However, recent projects such as PMIP (the Palaeoclimate Modelling Intercomparison Project) have emphasised the need to explore the dependency of past climate predictions on the specific climate model which is used. Here we present a comparison of MPWP climatologies produced by three atmosphere only GCMs from the Goddard Institute of Space Studies (GISS), the National Centre for Atmospheric Research (NCAR) and the Hadley Centre for Climate Prediction and Research (GCMAM3, CAM3-CLM and HadAM3 respectively). We focus on the ability of the GCMs to simulate climate fields needed to drive an offline ice sheet model to assess whether there are any significant differences between the climatologies. By taking the different temperature and precipitation predictions simulated by the three models as a forcing, and adopting GCM-specific topography, we have used the British Antarctic Survey thermomechanically coupled ice sheet model (BASISM) to test the extent to which equilibrium state ice sheets in the Northern Hemisphere are GCM dependent. Initial results which do not use GCM-specific topography suggest that employing different GCM climatologies with only small differences in surface air temperature and precipitation has a dramatic effect on the resultant Greenland ice sheet, where the end-member ice sheets vary from near modern to almost zero ice volume. As an extension of this analysis, we will also present results using a second ice sheet model (Glimmer), with a view to testing the degree to which end-member ice sheets are ice sheet model dependent, something which has not previously been addressed. Initially, BASISM and Glimmer will be internally optimised for performance, but we will also present a comparison where BASISM will be configured to the Glimmer model setup in a further test of ice sheet model dependency.

Dolan, Aisling; Haywood, Alan; Lunt, Daniel; Hill, Daniel

2010-05-01

294

Projected climate regime shift under future global warming from multi-model, multi-scenario CMIP5 simulations  

NASA Astrophysics Data System (ADS)

This study examined shifts in climate regimes over the global land area using the Köppen-Trewartha (K-T) climate classification by analyzing observations during 1900-2010, and simulations during 1900-2100 from twenty global climate models participating in Phase 5 of the Coupled Model Inter-comparison Project (CMIP5). Under the Intergovernmental Panel on Climate Change Representative Concentration Pathways 8.5 (RCP8.5) scenario, the models projected a 3°-10 °C warming in annual temperature over the global land area by the end of the twenty-first century, with strong (moderate) warming in the high (middle) latitudes of the Northern Hemisphere and weaker warming in the tropics and the Southern Hemisphere. The projected changes in precipitation vary considerably in space and present greater uncertainties among the models. Overall, the models are consistent in projecting increasing precipitation over the high-latitude of the Northern Hemisphere, and reduced precipitation in the Mediterranean, southwestern North America, northern and southern Africa and Australia. Based on the projected changes in temperature and precipitation, the K-T climate types would shift toward warmer and drier climate types from the current climate distribution. Regions of temperate, tropical and dry climate types are projected to expand, while regions of polar, sub-polar and subtropical climate types are projected to contract. The magnitudes of the projected changes are stronger in the RCP8.5 scenario than the low emission scenario RCP4.5. On average, the climate types in 31.4% and 46.3% of the global land area are projected to change by the end of the twenty-first century under RCP4.5 and RCP8.5 scenarios, respectively. Further analysis suggests that changes in precipitation played a slightly more important role in causing shifts of climate type during the twentieth century. However, the projected changes in temperature play an increasingly important role and dominate shifts in climate type when the warming becomes more pronounced in the twenty-first century.

Feng, Song; Hu, Qi; Huang, Wei; Ho, Chang-Hoi; Li, Ruopu; Tang, Zhenghong

2014-01-01

295

Strong atmospheric chemistry feedback to climate warming from Arctic methane emissions  

USGS Publications Warehouse

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.

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

2011-01-01

296

Mechanisms producing warm-climate ice retreat in East Antarctic subglacial basins  

NASA Astrophysics Data System (ADS)

Geological data indicate that global sea level has fluctuated on O(10,000) to O(1,000,000) year time scales during the last ~25 million years. Peak levels are uncertain, but some estimates suggest high stands of ~20 m or more above modern, for instance during the mid Pliocene. If correct, this implies substantial variations in the size of the East Antarctic Ice Sheet (EAIS). However, climate and ice-sheet models have not been able to simulate significant EAIS retreat from continental size, given low proxy atmospheric CO2 levels during this time. Here, we use a continental Antarctic ice-sheet model with two new mechanisms based on previous studies and observations: (1) structural failure of large tidewater ice cliffs, and (2) enhanced ice-shelf calving due to meltwater drainage into crevasses. With atmospheric and oceanic forcing representing Pliocene warm periods, the new mechanisms greatly accelerate the expected collapse of marine ice in West Antarctica, and also cause drastic retreat into 3 major East Antarctic subglacial basins, producing ~15 m global sea-level rise within a few thousand years. Basic results are presented, along with details of the cliff-failure numerics, and a simple parameterization of the clogging effects of ice melange in narrow seaways, which aids in ice-sheet recovery after colder climates resume.

Pollard, David; DeConto, Robert

2014-05-01

297

Stratosphere key for wintertime atmospheric response to warm Atlantic decadal conditions  

NASA Astrophysics Data System (ADS)

There is evidence that the observed changes in winter North Atlantic Oscillation (NAO) drive a significant portion of Atlantic Multi Decadal Variability (AMV). However, whether the observed decadal NAO changes can be forced by the ocean is controversial. There is also evidence that artificially imposed multi-decadal stratospheric changes can impact the troposphere in winter. But the origins of such stratospheric changes are still unclear, especially in early to mid winter, where the radiative ozone-impact is negligible. Here we show, through observational analysis and atmospheric model experiments, that large-scale Atlantic warming associated with AMV drives high-latitude precursory stratospheric warming in early to mid winter that propagates downward resulting in a negative tropospheric NAO in late winter. The mechanism involves stratosphere/troposphere dynamical coupling, and can be simulated to a large extent, but only with a stratosphere resolving model (i.e., high-top). Further analysis shows that this precursory stratospheric response can be explained by the shift of the daily extremes toward more major stratospheric warming events. This shift cannot be simulated with the atmospheric (low-top) model configuration that poorly resolves the stratosphere and implements a sponge layer in upper model levels. While the potential role of the stratosphere in multi-decadal NAO and Atlantic meridional overturning circulation changes has been recognised, our results show that the stratosphere is an essential element of extra-tropical atmospheric response to ocean variability. Our findings suggest that the use of stratosphere resolving models should improve the simulation, prediction, and projection of extra-tropical climate, and lead to a better understanding of natural and anthropogenic climate change.

Omrani, N.-E.; Keenlyside, N. S.; Bader, Jürgen; Manzini, Elisa

2014-02-01

298

Global warming and climate forcing by recent albedo changes on Mars  

USGS Publications Warehouse

For hundreds of years, scientists have tracked the changing appearance of Mars, first by hand drawings and later by photographs. Because of this historical record, many classical albedo patterns have long been known to shift in appearance over time. Decadal variations of the martian surface albedo are generally attributed to removal and deposition of small amounts of relatively bright dust on the surface. Large swaths of the surface (up to 56 million km2) have been observed to darken or brighten by 10 per cent or more. It is unknown, however, how these albedo changes affect wind circulation, dust transport and the feedback between these processes and the martian climate. Here we present predictions from a Mars general circulation model, indicating that the observed interannual albedo alterations strongly influence the martian environment. Results indicate enhanced wind stress in recently darkened areas and decreased wind stress in brightened areas, producing a positive feedback system in which the albedo changes strengthen the winds that generate the changes. The simulations also predict a net annual global warming of surface air temperatures by ???0.65 K, enhancing dust lifting by increasing the likelihood of dust devil generation. The increase in global dust lifting by both wind stress and dust devils may affect the mechanisms that trigger large dust storm initiation, a poorly understood phenomenon, unique to Mars. In addition, predicted increases in summertime air temperatures at high southern latitudes would contribute to the rapid and steady scarp retreat that has been observed in the south polar residual ice for the past four Mars years. Our results suggest that documented albedo changes affect recent climate change and large-scale weather patterns on Mars, and thus albedo variations are a necessary component of future atmospheric and climate studies. ??2007 Nature Publishing Group.

Fenton, L.K.; Geissler, P.E.; Haberle, R.M.

2007-01-01

299

Global warming and climate forcing by recent albedo changes on Mars.  

PubMed

For hundreds of years, scientists have tracked the changing appearance of Mars, first by hand drawings and later by photographs. Because of this historical record, many classical albedo patterns have long been known to shift in appearance over time. Decadal variations of the martian surface albedo are generally attributed to removal and deposition of small amounts of relatively bright dust on the surface. Large swaths of the surface (up to 56 million km2) have been observed to darken or brighten by 10 per cent or more. It is unknown, however, how these albedo changes affect wind circulation, dust transport and the feedback between these processes and the martian climate. Here we present predictions from a Mars general circulation model, indicating that the observed interannual albedo alterations strongly influence the martian environment. Results indicate enhanced wind stress in recently darkened areas and decreased wind stress in brightened areas, producing a positive feedback system in which the albedo changes strengthen the winds that generate the changes. The simulations also predict a net annual global warming of surface air temperatures by approximately 0.65 K, enhancing dust lifting by increasing the likelihood of dust devil generation. The increase in global dust lifting by both wind stress and dust devils may affect the mechanisms that trigger large dust storm initiation, a poorly understood phenomenon, unique to Mars. In addition, predicted increases in summertime air temperatures at high southern latitudes would contribute to the rapid and steady scarp retreat that has been observed in the south polar residual ice for the past four Mars years. Our results suggest that documented albedo changes affect recent climate change and large-scale weather patterns on Mars, and thus albedo variations are a necessary component of future atmospheric and climate studies. PMID:17410170

Fenton, Lori K; Geissler, Paul E; Haberle, Robert M

2007-04-01

300

Influence of Climate Warming on Arctic Mammals? New Insights from Ancient DNA Studies of the Collared Lemming Dicrostonyx torquatus  

PubMed Central

Background Global temperature increased by approximately half a degree (Celsius) within the last 150 years. Even this moderate warming had major impacts on Earth's ecological and biological systems, especially in the Arctic where the magnitude of abiotic changes even exceeds those in temperate and tropical biomes. Therefore, understanding the biological consequences of climate change on high latitudes is of critical importance for future conservation of the species living in this habitat. The past 25,000 years can be used as a model for such changes, as they were marked by prominent climatic changes that influenced geographical distribution, demographic history and pattern of genetic variation of many extant species. We sequenced ancient and modern DNA of the collared lemming (Dicrostonyx torquatus), which is a key species of the arctic biota, from a single site (Pymva Shor, Northern Pre Urals, Russia) to see if climate warming events after the Last Glacial Maximum had detectable effects on the genetic variation of this arctic rodent species, which is strongly associated with a cold and dry climate. Results Using three dimensional network reconstructions we found a dramatic decline in genetic diversity following the LGM. Model-based approaches such as Approximate Bayesian Computation and Markov Chain Monte Carlo based Bayesian inference show that there is evidence for a population decline in the collared lemming following the LGM, with the population size dropping to a minimum during the Greenland Interstadial 1 (Bølling/Allerød) warming phase at 14.5 kyrs BP. Conclusion Our results show that previous climate warming events had a strong influence on genetic diversity and population size of collared lemmings. Due to its already severely compromised genetic diversity a similar population reduction as a result of the predicted future climate change could completely abolish the remaining genetic diversity in this population. Local population extinctions of collared lemmings 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. PMID:20523724

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

2010-01-01

301

Understanding the Causes of Recent Warming of Mediterranean Waters. How Much Could Be Attributed to Climate Change?  

PubMed Central

During the past two decades, Mediterranean waters have been warming at a rather high rate resulting in scientific and social concern. This warming trend is observed in satellite data, field data and model simulations, and affects both surface and deep waters throughout the Mediterranean basin. However, the warming rate is regionally different and seems to change with time, which has led to the question of what causes underlie the observed trends. Here, we analyze available satellite information on sea surface temperature (SST) from the last 25 years using spectral techniques and find that more than half of the warming tendency during this period is due to a non-linear, wave-like tendency. Using a state of the art hydrodynamic model, we perform a hindcast simulation and obtain the simulated SST evolution of the Mediterranean basin for the last 52 years. These SST results show a clear sinusoidal tendency that follows the Atlantic Multidecadal Oscillation (AMO) during the simulation period. Our results reveal that 58% of recent warming in Mediterranean waters could be attributed to this AMO-like oscillation, being anthropogenic-induced climate change only responsible for 42% of total trend. The observed acceleration of water warming during the 1990s therefore appears to be caused by a superimposition of anthropogenic-induced warming with the positive phase of the AMO, while the recent slowdown of this tendency is likely due to a shift in the AMO phase. It has been proposed that this change in the AMO phase will mask the effect of global warming in the forthcoming decades, and our results indicate that the same could also be applicable to the Mediterranean Sea. Henceforth, natural multidecadal temperature oscillations should be taken into account to avoid underestimation of the anthropogenic-induced warming of the Mediterranean basin in the future. PMID:24312322

Macias, Diego; Garcia-Gorriz, Elisa; Stips, Adolf

2013-01-01

302

Understanding the causes of recent warming of mediterranean waters. How much could be attributed to climate change?  

PubMed

During the past two decades, Mediterranean waters have been warming at a rather high rate resulting in scientific and social concern. This warming trend is observed in satellite data, field data and model simulations, and affects both surface and deep waters throughout the Mediterranean basin. However, the warming rate is regionally different and seems to change with time, which has led to the question of what causes underlie the observed trends. Here, we analyze available satellite information on sea surface temperature (SST) from the last 25 years using spectral techniques and find that more than half of the warming tendency during this period is due to a non-linear, wave-like tendency. Using a state of the art hydrodynamic model, we perform a hindcast simulation and obtain the simulated SST evolution of the Mediterranean basin for the last 52 years. These SST results show a clear sinusoidal tendency that follows the Atlantic Multidecadal Oscillation (AMO) during the simulation period. Our results reveal that 58% of recent warming in Mediterranean waters could be attributed to this AMO-like oscillation, being anthropogenic-induced climate change only responsible for 42% of total trend. The observed acceleration of water warming during the 1990s therefore appears to be caused by a superimposition of anthropogenic-induced warming with the positive phase of the AMO, while the recent slowdown of this tendency is likely due to a shift in the AMO phase. It has been proposed that this change in the AMO phase will mask the effect of global warming in the forthcoming decades, and our results indicate that the same could also be applicable to the Mediterranean Sea. Henceforth, natural multidecadal temperature oscillations should be taken into account to avoid underestimation of the anthropogenic-induced warming of the Mediterranean basin in the future. PMID:24312322

Macias, Diego; Garcia-Gorriz, Elisa; Stips, Adolf

2013-01-01

303

Scientist warns against overselling climate change Climate change forecasters should admit that they cannot predict how global warming will affect  

E-print Network

that they cannot predict how global warming will affect individual countries, a leading physicist has said-of-deaths-from-ozone-predicted.html) Antarctic sea floor gives clues about effects of future global warming (/earth/environment/climatechange /5279223/Antarctic-sea-floor-gives-clues-about-affects-of-future-global-warming.html) The Vanishing Face

Stevenson, Paul

304

Vegetation types and climate conditions reflected by the modern phytolith assemblages in the subalpine Dalaoling Forest Reserve, central China  

NASA Astrophysics Data System (ADS)

This research describes modern phytolith records and distributions from subalpine surface soils in the Dalaoling Forest Reserve, and reveals its implications for local climate conditions with respect to the altitude gradient. Well-preserved phytolith morpho-types, assemblages, and climatic indices were used to study the relationship between local vegetation and climate conditions. The phytolith classification system is mainly based on the characteristics of detailed morpho-types described for anatomical terms, which are divided into seven groups: long cells, short cells, bulliform cells, hair cells, pteridophyte type, broad-leaved type, and gymnosperm type. Phytoliths originating from the Poaceae are composed of Pooideae (rondel and trapeziform), Panicoideae (bilobate, cross, and polylobate), Chloridoideae (short/square saddle), and Bambusoideae (oblong concave saddle). Based on the altitudinal distribution of the phytolith assemblages and the indices of aridity (Iph), climate (Ic), and tree cover density (D/P), five phytolith assemblage zones have revealed the five types of climatic conditions ranging from 1,169 m to 2,005 m in turn: warm-wet, warm-xeric to warm-mesic, warm-xeric to cool-mesic, cool-xeric, and cool-mesic to cool-xeric. The Bambusoideae, Panicoideae, and Chloridoideae are the dominant vegetation at the lower-middle of the mountains, while Pooideae is mainly distributed in the higher mountains. The close relationship between phytolith assembleages and changes of altitude gradient suggest that vegetation distribution patterns and plant ecology in the Dalaoling mountains are controlled by temperature and humidity conditions. Our results highlight the importance of phytolith records as reliable ecoclimatic indicators for vegetation ecology in subtropical regions.

Traoré, Djakanibé Désiré; Gu, Yansheng; Liu, Humei; Shemsanga, Ceven; Ge, Jiwen

2014-11-01

305

Development of probability distributions for regional climate change from uncertain global mean warming and an uncertain scaling relationship  

NASA Astrophysics Data System (ADS)

To produce probability distributions for regional climate change in surface temperature and precipitation, a probability distribution for global mean temperature increase has been combined with the probability distributions for the appropriate scaling variables, i.e. the changes in regional temperature/precipitation per degree global mean warming. Each scaling variable is assumed to be normally distributed. The uncertainty of the scaling relationship arises from systematic differences between the regional changes from global and regional climate model simulations and from natural variability. The contributions of these sources of uncertainty to the total variance of the scaling variable are estimated from simulated temperature and precipitation data in a suite of regional climate model experiments conducted within the framework of the EU-funded project PRUDENCE, using an Analysis Of Variance (ANOVA). For the area covered in the 2001 2004 EU-funded project SWURVE, five case study regions (CSRs) are considered: NW England, the Rhine basin, Iberia, Jura lakes (Switzerland) and Mauvoisin dam (Switzerland). The resulting regional climate changes for 2070 2099 vary quite significantly between CSRs, between seasons and between meteorological variables. For all CSRs, the expected warming in summer is higher than that expected for the other seasons. This summer warming is accompanied by a large decrease in precipitation. The uncertainty of the scaling ratios for temperature and precipitation is relatively large in summer because of the differences between regional climate models. Differences between the spatial climate-change patterns of global climate model simulations make significant contributions to the uncertainty of the scaling ratio for temperature. However, no meaningful contribution could be found for the scaling ratio for precipitation due to the small number of global climate models in the PRUDENCE project and natural variability, which is often the largest source of uncertainty. In contrast, for temperature, the contribution of natural variability to the total variance of the scaling ratio is small, in particular for the annual mean values. Simulation from the probability distributions of global mean warming and the scaling ratio results in a wider range of regional temperature change than that in the regional climate model experiments. For the regional change in precipitation, however, a large proportion of the simulations (about 90%) is within the range of the regional climate model simulations.

Hingray, B.; Mezghani, A.; Buishand, T. A.

2007-04-01

306

Groundwater recharge simulation under the steady-state and transient climate conditions  

NASA Astrophysics Data System (ADS)

Groundwater recharge simulation under the steady-state and transient climate conditions Diffusive groundwater recharge is a vertical water flux through the water table, i.e. through the boundary between the unsaturated and saturated zones. This flux features temporal and spatial changes due to variations in the climatic conditions, landscape the state of vegetation, and the spatial variability of vadoze zone characteristics. In a changing climate the non-steady state series of climatic characteristics will affect on the groundwater recharge.. A well-tested approach to calculating water flux through the vadoze zone is the application of Richard’s equations for a heterogeneous one-domain porosity continuum with specially formulated atmospheric boundary conditions at the ground surface. In this approach the climatic parameters are reflected in upper boundary conditions, while the recharge series is the flux through the low boundary. In this work developed by authors code Surfbal that simulates water cycle at surface of topsoil to take into account the various condition of precipitation transformation at the surface in different seasons under different vegetation cover including snow accumulation in winter and melting in spring is used to generate upper boundary condition at surface of topsoil for world-wide known Hydrus-1D code (Simunek et al, 2008). To estimate the proposal climate change effect we performed Surfbal and Hydrus simulation using the steady state climatic condition and transient condition due to global warming on example of Moscow region, Russia. The following scenario of climate change in 21 century in Moscow region was selected: the annual temperature will increase on 4C during 100 year and annual precipitation will increase on 10% (Solomon et al, 2007). Within the year the maximum increasing of temperature and precipitation falls on winter time, while in middle of summer temperature will remain almost the same as observed now and monthly precipitation. For simulating climate input the weather generator LARSWG (Semenov and Barrow 1997) was trained for generation daily meteorological records for both steady state and transient climatic conditions and two 100 year of meteorological series of minimum and maximum of air temperature, solar radiation and precipitation were generated. The numerical experiment for studying of transient climate on groundwater was performed for typical vadoze zone parameters of western part of Moscow Artesian basin. As the result, the 100 years series of recharge were simulated. Examination of stochastic properties of simulated time-series and comparative analysis series for the transient and for the steady state conditions shows the trend of increasing of recharge in this region in transient climate. Analysis of daily and monthly simulated water balance shows that this increasing is result of winter snow melting and winter infiltration into thaw topsoil. This work was supported by Russian Foundation for Basic Research via grant 08-05-00720a REFERENCES Semenov M.A and Barrow E.M., 1997. Use of a stochastic weather generator in the development of climate change scenarios. Climatic Change, 35:397-414 Šim?nek, J., M. Th. van Genuchten, and M. Šejna, 2008. Development and applications of the HYDRUS and STANMOD software packages, and related codes, Vadose Zone Journal, doi:10.2136/VZJ2007.0077, Special Issue "Vadose Zone Modeling", 7(2), 587-600. Solomon, S., D. Qin, M. Manning, Technical Summary. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

Pozdniakov, S.; Lykhina, N.

2010-03-01

307

24 CFR 3285.404 - Severe climatic conditions.  

Code of Federal Regulations, 2011 CFR

...3285.404 Severe climatic conditions. In frost-susceptible soil locations, ground anchor augers must be installed below the frost line, unless the foundation system is frost-protected to prevent the effects of...

2011-04-01

308

24 CFR 3285.404 - Severe climatic conditions.  

Code of Federal Regulations, 2012 CFR

...3285.404 Severe climatic conditions. In frost-susceptible soil locations, ground anchor augers must be installed below the frost line, unless the foundation system is frost-protected to prevent the effects of...

2012-04-01

309

24 CFR 3285.404 - Severe climatic conditions.  

Code of Federal Regulations, 2013 CFR

...3285.404 Severe climatic conditions. In frost-susceptible soil locations, ground anchor augers must be installed below the frost line, unless the foundation system is frost-protected to prevent the effects of...

2013-04-01

310

24 CFR 3285.404 - Severe climatic conditions.  

...3285.404 Severe climatic conditions. In frost-susceptible soil locations, ground anchor augers must be installed below the frost line, unless the foundation system is frost-protected to prevent the effects of...

2014-04-01

311

Potential increase of flood hazards in Korea due to global warming from a high-resolution regional climate simulation  

NASA Astrophysics Data System (ADS)

Because of the importance of the changes in the hydrologic cycle, accurate assessment of precipitation characteristics is essential to understand the impact of climate change due to global warming. This study investigates the changes in extreme precipitation with sub-daily and daily temporal scales. For a fine-scale climate change projection focusing on the Korean peninsula (20 km), we performed the dynamical downscaling of the global climate scenario covering the period 1971-2100 (130-year) simulated by the Max-Planck-Institute global climate model, ECHAM5, using the latest version of the International Centre for Theoretical Physics (ICTP) regional climate model, RegCM3. While annual mean precipitation exhibits a pronounced interannual and interdecadal variability, with the increasing or decreasing trend repeated during a certain period, extreme precipitation with sub-daily and daily temporal scales estimated from the generalized extreme value distribution shows consistently increasing pattern. The return period of extreme precipitation is significantly reduced despite the decreased annual mean precipitation at the end of 21st century. The decreased relatively weak precipitation is responsible for the decreased total precipitation, so that the decreased total precipitation does not necessarily mean less heavy precipitation. Climate change projection based on the ECHAM5-RegCM3 model chain clearly shows the effect of global warming in increasing the intensity and frequency of extreme precipitation, even without significantly increased total precipitation, which implies an increased risk for flood hazards.

Im, Eun-Soon; Lee, Byong-Ju; Kwon, Ji-Hye; in, So-Ra; Han, Sang-Ok

2012-02-01

312

Global Warming  

NSDL National Science Digital Library

Use the links below to complete your research. The Heat Over Global Warming God and Global Warming Robert Redford: Business Warming Up to Environment Emission Impossible? Senator Stepping Up on Climate Control Interview: Bill McKibben Climate Change and the Media Senate Hearings Five Questions with Environmental Writer Tom Philpott Home Grown Oil, Politics Bribes E2: Energy The Greens Online NewsHour: The Global Warming Debate NewsHour Extra: Global Warming Linked to Humans NewsHour Extra: Global Warming Fears Lead to Ratification of the Kyoto Protocol Frontline: Doubters of Global Warming Journey to Planet Earth: The State of the Planet: Global Warming What s Up With the Weather? Some of the below resources were found in the book Global Warming : Opposing Viewpoints (available in the MRC) The Heritage Foundation - Global Warming Rainforest Alliance Doing a global warming search in this website will result in a list of various articles Sierra Club - homepage eLibrary (Proquest) is now available through the

Ms. Schultz

2007-12-03

313

Is bias correction of regional climate model (RCM) simulations possible for non-stationary conditions?  

NASA Astrophysics Data System (ADS)

In hydrological climate-change impact studies, regional climate models (RCMs) are commonly used to transfer large-scale global climate model (GCM) data to smaller scales and to provide more detailed regional information. Due to systematic and random model errors, however, RCM simulations often show considerable deviations from observations. This has led to the development of a number of correction approaches that rely on the assumption that RCM errors do not change over time. It is in principle not possible to test whether this underlying assumption of error stationarity is actually fulfilled for future climate conditions. In this study, however, we demonstrate that it is possible to evaluate how well correction methods perform for conditions different from those used for calibration with the relatively simple differential split-sample test. For five Swedish catchments, precipitation and temperature simulations from 15 different RCMs driven by ERA40 (the 40 yr reanalysis product of the European Centre for Medium-Range Weather Forecasts (ECMWF)) were corrected with different commonly used bias correction methods. We then performed differential split-sample tests by dividing the data series into cold and warm respective dry and wet years. This enabled us to cross-evaluate the performance of different correction procedures under systematically varying climate conditions. The differential split-sample test identified major differences in the ability of the applied correction methods to reduce model errors and to cope with non-stationary biases. More advanced correction methods performed better, whereas large deviations remained for climate model simulations corrected with simpler approaches. Therefore, we question the use of simple correction methods such as the widely used delta-change approach and linear transformation for RCM-based climate-change impact studies. Instead, we recommend using higher-skill correction methods such as distribution mapping.

Teutschbein, C.; Seibert, J.

2013-12-01

314

Characterisation of the supraorbital foramen and notch as an exit route for the supraorbital nerve in populations from different climatic conditions.  

PubMed

The aim of this study was to obtain morphological data on the supraorbital foramina and notches related to sex and side of the skull in populations from different climatic conditions. We assume that the type and frequency of these supraorbital structures may depend on the climatic conditions in which the population lived. Populations from colder regions should have a higher frequency of foramina and populations from warmer climates should have a higher frequency of supraorbital notches than other populations. This may be a result of adaptive changes and developmental responses to ambient temperatures, for prevention of heat loss in the supraorbital neurovascular bundle passing through these supraorbital structures. Localisation of the supraorbital neurovascular bundle is higher and deeper when it passes through the foramen than in the notch. A total of 1978 orbits from 989 skulls collected in three climatic regions: warm, temperate and cold, were analysed. The highest frequency of supraorbital foramina (35.4%) was in skulls from cold climatic conditions. In samples from warm climates, the frequency of supraorbital foramina was lowest (16.4%). In contrast, the frequency of supraorbital notches was highest in the sample from warm climates (54.5%), and lowest in the sample from cold climatic conditions (44.0%). Statistically significant differences in the frequency of supraorbital structures were found between cold climate sample and the other two samples (p<0.05). Our results suggest a relationship between the type of supraorbital structure and climatic conditions as an adaptation to cold climate and thermoregulatory processes concerning the human head. This research is of direct relevance to clinical practice, and drawing attention to the differences in the frequency of these supraorbital structures may help surgeons to avoid injuring the neurovascular bundles. These data and studies may also contribute to the understanding of the impact of climate on the morphology of modern European skulls. PMID:23218648

Tomaszewska, A; Tomczyk, J; Kwiatkowska, B

2013-02-01

315

Modeling the effects of fire severity and climate warming on active layer thickness and soil carbon storage of black spruce forests across the landscape in interior Alaska  

SciTech Connect

There is a substantial amount of carbon stored in the permafrost soils of boreal forest ecosystems, where it is currently protected from decomposition. The surface organic horizons insulate the deeper soil from variations in atmospheric temperature. The removal of these insulating horizons through consumption by fire increases the vulnerability of permafrost to thaw, and the carbon stored in permafrost to decomposition. In this study we ask how warming and fire regime may influence spatial and temporal changes in active layer and carbon dynamics across a boreal forest landscape in interior Alaska. To address this question, we (1) developed and tested a predictive model of the effect of fire severity on soil organic horizons that depends on landscape-level conditions and (2) used this model to evaluate the long-term consequences of warming and changes in fire regime on active layer and soil carbon dynamics of black spruce forests across interior Alaska. The predictive model of fire severity, designed from the analysis of field observations, reproduces the effect of local topography (landform category, the slope angle and aspect and flow accumulation), weather conditions (drought index, soil moisture) and fire characteristics (day of year and size of the fire) on the reduction of the organic layercaused by fire. The integration of the fire severity model into an ecosystem process-based model allowed us to document the relative importance and interactions among local topography, fire regime and climate warming on active layer and soil carbon dynamics. Lowlands were more resistant to severe fires and climate warming, showing smaller increases in active layer thickness and soil carbon loss compared to drier flat uplands and slopes. In simulations that included the effects of both warming and fire at the regional scale, fire was primarily responsible for a reduction in organic layer thickness of 0.06 m on average by 2100 that led to an increase in active layer thickness of 1.1 m on average by 2100. The combination of warming and fire led to a simulated cumulative loss of 9.6 kgC m 2 on average by 2100. Our analysis suggests that ecosystem carbon storage in boreal forests in interior Alaska is particularly vulnerable, primarily due to the combustion of organic layer thickness in fire and the related increase in active layer thickness that exposes previously protected permafrost soil carbon to decomposition.

Genet, Helene [Institute of Arctic Biology (IAB), University of Alaska, Fairbanks (UAF)] [Institute of Arctic Biology (IAB), University of Alaska, Fairbanks (UAF); McGuire, A. David [University of Alaska] [University of Alaska; Barrett, K. [USGS Alaska Science Center] [USGS Alaska Science Center; Breen, Amy [International Arctic Research Center, SNAP, University of Alaska, Fairbanks (UAF)] [International Arctic Research Center, SNAP, University of Alaska, Fairbanks (UAF); Euskirchen, Eugenie S [University of Alaska] [University of Alaska; Johnstone, J. F. [University of Saskatchewan] [University of Saskatchewan; Kasischke, Eric S. [University of Maryland, College Park] [University of Maryland, College Park; Melvin, A. M. [University of Florida, Gainesville] [University of Florida, Gainesville; Bennett, A. [International Arctic Research Center, SNAP, University of Alaska, Fairbanks (UAF)] [International Arctic Research Center, SNAP, University of Alaska, Fairbanks (UAF); Mack, M. C. [University of Florida, Gainesville] [University of Florida, Gainesville; Rupp, Scott T. [International Arctic Research Center, SNAP, University of Alaska, Fairbanks (UAF)] [International Arctic Research Center, SNAP, University of Alaska, Fairbanks (UAF); Schuur, Edward [University of Florida] [University of Florida; Turetsky, M. R. [University of Guelph, Canada] [University of Guelph, Canada; Yuan, Fengming [ORNL] [ORNL

2013-01-01

316

Modeling the effects of fire severity and climate warming on active layer and soil carbon dynamics of black spruce forests across the landscape in interior Alaska  

USGS Publications Warehouse

There is a substantial amount of carbon stored in the permafrost soils of boreal forest ecosystems, where it is currently protected from decomposition. The surface organic horizons insulate the deeper soil from variations in atmospheric temperature. The removal of these insulating horizons through consumption by fire increases the vulnerability of permafrost to thaw, and the carbon stored in permafrost to decomposition. In this study we ask how warming and fire regime may influence spatial and temporal changes in active layer and carbon dynamics across a boreal forest landscape in interior Alaska. To address this question, we (1) developed and tested a predictive model of the effect of fire severity on soil organic horizons that depends on landscape-level conditions and (2) used this model to evaluate the long-term consequences of warming and changes in fire regime on active layer and soil carbon dynamics of black spruce forests across interior Alaska. The predictive model of fire severity, designed from the analysis of field observations, reproduces the effect of local topography (landform category, the slope angle and aspect and flow accumulation), weather conditions (drought index, soil moisture) and fire characteristics (day of year and size of the fire) on the reduction of the organic layer caused by fire. The integration of the fire severity model into an ecosystem process-based model allowed us to document the relative importance and interactions among local topography, fire regime and climate warming on active layer and soil carbon dynamics. Lowlands were more resistant to severe fires and climate warming, showing smaller increases in active layer thickness and soil carbon loss compared to drier flat uplands and slopes. In simulations that included the effects of both warming and fire at the regional scale, fire was primarily responsible for a reduction in organic layer thickness of 0.06 m on average by 2100 that led to an increase in active layer thickness of 1.1 m on average by 2100. The combination of warming and fire led to a simulated cumulative loss of 9.6 kgC m?2 on average by 2100. Our analysis suggests that ecosystem carbon storage in boreal forests in interior Alaska is particularly vulnerable, primarily due to the combustion of organic layer thickness in fire and the related increase in active layer thickness that exposes previously protected permafrost soil carbon to decomposition.

Genet, H.; McGuire, Anthony D.; Barrett, K.; Breen, A.; Euskirchen, E.S.; Johnstone, J.F.; Kasischke, E.S.; Melvin, A.M.; Bennett, A.; Mack, M.C.; Rupp, T.S.; Schuur, A.E.G.; Turetsky, M.R.; Yuan, F.

2013-01-01

317

Enviropedia: Introduction to Global Warming  

NSDL National Science Digital Library

This resource provides an overview of the concept of global warming, which is thought to be due to man-made emissions of greenhouse gases, which are largely a result of the burning of fossil fuels and deforestation. It explores the possibility that the impacts of global warming may include desertification and the destruction of other ecosystems, extreme weather conditions, and a danger to agriculture. Information on the Intergovernmental Panel on Climate Change, (IPCC), the Kyoto Protocol, the United Nations Framework Convention on Climate Change, (FCCC), and the United Kingdom Programme on Climate Change is also provided.

318

Aerosol-Induced Changes of Convective Cloud Anvils Produce Strong Climate Warming  

NASA Technical Reports Server (NTRS)

The effect of aerosol on clouds poses one of the largest uncertainties in estimating the anthropogenic contribution to climate change. Small human-induced perturbations to cloud characteristics via aerosol pathways can create a change in the top-of-atmosphere radiative forcing of hundreds of Wm(exp-2) . Here we focus on links between aerosol and deep convective clouds of the Atlantic and Pacific Intertropical Convergence Zones, noting that the aerosol environment in each region is entirely different. The tops of these vertically developed clouds consisting of mostly ice can reach high levels of the atmosphere, overshooting the lower stratosphere and reaching altitudes greater than 16 km. We show a link between aerosol, clouds and the free atmosphere wind profile that can change the magnitude and sign of the overall climate radiative forcing. We find that increased aerosol loading is associated with taller cloud towers and anvils. The taller clouds reach levels of enhanced wind speeds that act to spread and thin the anvi1 clouds, increasing areal coverage and decreasing cloud optical depth. The radiative effect of this transition is to create a positive radiative forcing (warming) at top-of-atmosphere. Furthermore we introduce the cloud optical depth (r), cloud height (Z) forcing space and show that underestimation of radiative forcing is likely to occur in cases of non homogenous clouds. Specifically, the mean radiative forcing of towers and anvils in the same scene can be several times greater than simply calculating the forcing from the mean cloud optical depth in the scene. Limitations of the method are discussed, alternative sources of aerosol loading are tested and meteorological variance is restricted, but the trend of taller clouds; increased and thinner anvils associated with increased aerosol loading remains robust through all the different tests and perturbations.

Koren, I.; Remer, L. A.; Altaratz, O.; Martins, J. V.; Davidi, A.

2010-01-01

319

Arctic land hydrothermal sensitivity under warming: Idealized off-line evaluation of a physical terrestrial scheme in a global climate model  

NASA Astrophysics Data System (ADS)

A series of idealized one-dimensional off-line sensitivity experiments for the Arctic hydroclimate under a transitional warming environment were conducted to investigate the impact of different internal mechanisms and external forcing (excessive water input) in a physical terrestrial scheme, Minimal Advanced Treatments of Surface Interaction and Runoff (MATSIRO), used in a global climate model. The scheme has freeze/thaw processes and was run with the column depth greater than 50 m. The inclusion of the top organic layers and the physically based parameterization of soil hydrothermal properties led to a realistic seasonal amplitude of a subsurface thermal regime and mitigated the warming and deepening of the maximum active layer thickness (ALT). After a 6-K warming over 100 years, ALT increases by 67% (from 9.6 to 16 cm) with the top organic layers and increases by more than a factor of 2 for the default mineral layers (122% from 45 cm to 1.0 m). With the more realistic thermal property profile, the physically based parameterizations projected ALT after the 100-year warming to be about a half of what the original parameterization did (2.0 against 3.5 m). Finer soil layer thickness near the surface had impacts on the near-surface wetness and the energy and water exchange between the atmosphere and also showed greater tolerance to the misconfiguration of porosity profile, whose global-scale distribution is poorly known for global climate model applications. With much wetter forcing, water infiltration kept the soil close to the saturation, degradation of the frozen state proceeded faster, and the adaptation back to a drier condition occurred on a decadal time scale.

Saito, Kazuyuki

2008-11-01

320

Is the Climate of Bering Sea Warming and Affecting the Ecosystem?  

NASA Astrophysics Data System (ADS)

Observations from the Bering Sea are good indicators of decadal shifts in climate, as the Bering is a transition region between the cold, dry Arctic air mass to the north, and the moist, relatively warm maritime air mass to the south. The Bering Sea is also a transition region between Arctic and sub-Arctic ecosystems; this boundary can be loosely identified with the extent of winter sea-ice cover. Like a similar transition zone in the eastern North Atlantic, the Bering Sea is experiencing a northward biogeographical shift in response to changing temperature and atmospheric forcing. If this shift continues over the next decade, it will have major impacts on commercial and subsistence harvests as Arctic species are displaced by sub-Arctic species. The stakes are enormous, as this rich and diverse ecosystem currently provides 47% of the U.S. fishery production by weight, and is home to 80% of the U.S. sea bird population, 95% of northern fur seals, and major populations of Steller sea lions, walrus, and whales.

Overland, James E.; Stabeno, Phyllis J.

2004-08-01

321

Climate warming shifts carbon allocation from stemwood to roots in calcium-depleted spruce forests  

USGS Publications Warehouse

Increased greening of northern forests, measured by the Normalized Difference Vegetation Index (NDVI), has been presented as evidence that a warmer climate has increased both net primary productivity (NPP) and the carbon sink in boreal forests. However, higher production and greener canopies may accompany changes in carbon allocation that favor foliage or fine roots over less decomposable woody biomass. Furthermore, tree core data throughout mid- and northern latitudes have revealed a divergence problem (DP), a weakening in tree ring responses to warming over the past half century that is receiving increasing attention, but remains poorly understood. Often, the same sites exhibit trend inconsistency phenomenon (TIP), namely positive, or no trends in growing season NDVI where negative trends in tree ring indexes are observed. Here we studied growth of two Norway spruce (Picea abies) stands in western Russia that exhibited both the DP and TIP but were subject to soil acidification and calcium depletion of differing timing and severity. Our results link the decline in radial growth starting in 1980 to a shift in carbon allocation from wood to roots driven by a combination of two factors: (a) soil acidification that depleted calcium and impaired root function and (b) earlier onset of the growing season that further taxed the root system. The latter change in phenology appears to act as a trigger at both sites to push trees into nutrient limitation as the demand for Ca increased with the longer growing season, thereby causing the shift in carbon allocation.

Lapenis, Andrei Gennady; Lawrence, Gregory B.; Heim, Alexander; Zheng, Chengyang; Shortle, Walter

2013-01-01

322

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

PubMed

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

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

2010-01-01

323

Genotypic trait variation modifies effects of climate warming and nitrogen deposition on litter mass loss and microbial respiration.  

PubMed

Intraspecific variation in genotypically determined traits can influence ecosystem processes. Therefore, the impact of climate change on ecosystems may depend, in part, on the distribution of plant genotypes. Here we experimentally assess effects of climate warming and excess nitrogen supply on litter decomposition using 12 genotypes of a cosmopolitan foundation species collected across a 2100 km latitudinal gradient and grown in a common garden. Genotypically determined litter-chemistry traits varied substantially within and among geographic regions, which strongly affected decomposition and the magnitude of warming effects, as warming accelerated litter mass loss of high-nutrient, but not low-nutrient, genotypes. Although increased nitrogen supply alone had no effect on decomposition, it strongly accelerated litter mass loss of all genotypes when combined with warming. Rates of microbial respiration associated with the leaf litter showed nearly identical responses as litter mass loss. These results highlight the importance of interactive effects of environmental factors and suggest that loss or gain of genetic variation associated with key phenotypic traits can buffer, or exacerbate, the impact of global change on ecosystem process rates in the future. PMID:25099691

Hines, Jes; Reyes, Marta; Mozder, Thomas J; Gessner, Mark O

2014-12-01

324

Light and heavy fractions of soil organic matter in response to climate warming and increased precipitation in a temperate steppe.  

PubMed

Soil is one of the most important carbon (C) and nitrogen (N) pools and plays a crucial role in ecosystem C and N cycling. Climate change profoundly affects soil C and N storage via changing C and N inputs and outputs. However, the influences of climate warming and changing precipitation regime on labile and recalcitrant fractions of soil organic C and N remain unclear. Here, we investigated soil labile and recalcitrant C and N under 6 years' treatments of experimental warming and increased precipitation in a temperate steppe in Northern China. We measured soil light fraction C (LFC) and N (LFN), microbial biomass C (MBC) and N (MBN), dissolved organic C (DOC) and heavy fraction C (HFC) and N (HFN). The results showed that increased precipitation significantly stimulated soil LFC and LFN by 16.1% and 18.5%, respectively, and increased LFC:HFC ratio and LFN:HFN ratio, suggesting that increased precipitation transferred more soil organic carbon into the quick-decayed carbon pool. Experimental warming reduced soil labile C (LFC, MBC, and DOC). In contrast, soil heavy fraction C and N, and total C and N were not significantly impacted by increased precipitation or warming. Soil labile C significantly correlated with gross ecosystem productivity, ecosystem respiration and soil respiration, but not with soil moisture and temperature, suggesting that biotic processes rather than abiotic factors determine variations in soil labile C. Our results indicate that certain soil carbon fraction is sensitive to climate change in the temperate steppe, which may in turn impact ecosystem carbon fluxes in response and feedback to climate change. PMID:22479373

Song, Bing; Niu, Shuli; Zhang, Zhe; Yang, Haijun; Li, Linghao; Wan, Shiqiang

2012-01-01

325

Metrics for Ozone and Climate: Three-Dimensional Modeling Studies of Ozone Depletion Potentials and Indirect Global Warming Potentials  

Microsoft Academic Search

The concepts of ozone depletion potentials (ODPs) and global warming potentials (GWPs) have been extensively used in policy\\u000a consideration and scientific studies of ozone and climate issues. Most recent candidate-replacement compounds have atmospheric\\u000a lifetimes shorter than 1 year in order to limit their environmental effects. Especially for chemicals with extremely short\\u000a lifetimes, on the order of several to tens of

Donald J. Wuebbles; Daeok Youn; Ken Patten; Dong Wang; Mónica Martínez-Avilés

326

Light and Heavy Fractions of Soil Organic Matter in Response to Climate Warming and Increased Precipitation in a Temperate Steppe  

PubMed Central

Soil is one of the most important carbon (C) and nitrogen (N) pools and plays a crucial role in ecosystem C and N cycling. Climate change profoundly affects soil C and N storage via changing C and N inputs and outputs. However, the influences of climate warming and changing precipitation regime on labile and recalcitrant fractions of soil organic C and N remain unclear. Here, we investigated soil labile and recalcitrant C and N under 6 years' treatments of experimental warming and increased precipitation in a temperate steppe in Northern China. We measured soil light fraction C (LFC) and N (LFN), microbial biomass C (MBC) and N (MBN), dissolved organic C (DOC) and heavy fraction C (HFC) and N (HFN). The results showed that increased precipitation significantly stimulated soil LFC and LFN by 16.1% and 18.5%, respectively, and increased LFC?HFC ratio and LFN?HFN ratio, suggesting that increased precipitation transferred more soil organic carbon into the quick-decayed carbon pool. Experimental warming reduced soil labile C (LFC, MBC, and DOC). In contrast, soil heavy fraction C and N, and total C and N were not significantly impacted by increased precipitation or warming. Soil labile C significantly correlated with gross ecosystem productivity, ecosystem respiration and soil respiration, but not with soil moisture and temperature, suggesting that biotic processes rather than abiotic factors determine variations in soil labile C. Our results indicate that certain soil carbon fraction is sensitive to climate change in the temperate steppe, which may in turn impact ecosystem carbon fluxes in response and feedback to climate change. PMID:22479373

Song, Bing; Niu, Shuli; Zhang, Zhe; Yang, Haijun; Li, Linghao; Wan, Shiqiang

2012-01-01

327

Efficacy of Wrist/Palm Warming as an EVA Countermeasure to Maintain Finger Comfort in Cold Conditions During EVA  

NASA Technical Reports Server (NTRS)

This study explored the effectiveness of local wrist/palm warming as a potential countermeasure for providing finger comfort during extended duration EVA. Methods: Six subjects (5 males and 1 female) were evaluated in a sagitally divided liquid cooling/warming garment (LCWG) with modified liquid cooling/warming (LCW) gloves in three different experimental conditions. Condition 1: Stage 1- no LCWG; chamber adaptation with LCW glove inlet water temperature 33 C; Stage 2-LCW glove inlet water temperature cooled to 8 C; Stage 3-LCW glove inlet water temperature warmed to 45 C; Condition 2: Stage1-LCWG and LCW glove inlet water temperature 33 C; Stage 2-LCWG inlet temperature cooled to 31 C, LCW gloves, 8 C; Stage 3-LCWG inlet water temperature remains at 31 C, LCW glove inlet water temperature warmed to 45 C; Condition 3: Stage l -LCWG and LCW gloves 33 C; Stage 2-LCWG inlet water temperature cooled to 28 C, LCW gloves, 8 C; Stage 3-LCWG remains at 28 C, LCW glove water temperature warmed to 45 C. Results: Wrist/palm area warming significantly increased finger temperature (Tfing) and blood perfusion in Stage 3 compared to Stage 2. The LCW gloves were most effective in increasing Stage 3 Tfing in Condition 1; and in increasing blood perfusion in Conditions 1 and 2 compared to Condition 3. Ratings of subjective perception of heat in the hand and overall body heat were higher at Stage 3 than Stage 2, with no significant differences across Conditions. Conclusions: Local wrist/palm warming was effective in increasing blood circulation to the distal extremities, suggesting the potential usefulness of this technique for increasing astronaut thermal comfort during EVA while decreasing power requirements. The LCW gloves were effective in heating the highly cooled fingers when the overall body was in a mild heat deficit.

Koscheyev, Victor S.; Leon, Gloria R.; Trevino, Robert C.

2000-01-01

328

Practical precooling: Effect on cycling time trial performance in warm conditions  

Microsoft Academic Search

The purpose of this study was to compare the effects of two practical precooling techniques (skin cooling vs. skin + core cooling) on cycling time trial performance in warm conditions. Six trained cyclists completed one maximal graded exercise test ([Vdot]O2peak 71.4 ± 3.2 ml · kg · min) and four ?40 min laboratory cycling time trials in a heat chamber (34.3°C ± 1.1°C; 41.2% ± 3.0% rh) using a fixed-power\\/variable-power format. Cyclists prepared

Marc J. Quod; David T. Martin; Paul B. Laursen; Andrew S. Gardner; Shona L. Halson; Frank E. Marino; Margaret P. Tate; David E. Mainwaring; Christopher J. Gore; Allan G. Hahn

2006-01-01

329

Impact of a permanent El Ni?? (El Padre) and Indian Ocean Dipole in warm Pliocene climates  

USGS Publications Warehouse

Pliocene sea surface temperature data, as well as terrestrial precipitation and temperature proxies, indicate warmer than modern conditions in the eastern equatorial Pacific and imply permanent El Ni??o-like conditions with impacts similar to those of the 1997/1998 El Ni??o event. Here we use a general circulation model to examine the global-scale effects that result from imposing warm tropical sea surface temperature (SST) anomalies in both modern and Pliocene simulations. Observed SSTs from the 1997/1998 El Ni??o event were used for the ,anomalies and incorporate Pacific wanning as well as a prominent Indian Ocean Dipole event. Both the permanent El Ni??o (also called El Padre) and Indian Ocean Dipole (IOD) conditions are necessary to reproduce temperature and precipitation patterns consistent with the global distribution of Pliocene proxy data. These patterns may result from the poleward propagation of planetary waves from the strong convection centers associated with the El Ni??o and IOD. Copyright 2009 by the American Geophysical Union.

Shukla, S.P.; Chandler, M.A.; Jonas, J.; Sohl, L.E.; Mankoff, K.; Dowsett, H.

2009-01-01

330

Space Solar Patrol data and changes in weather and climate, including global warming  

NASA Astrophysics Data System (ADS)

In this paper, the results obtained during the execution of several ISTC projects are presented. The general aim of these projects has been the study of global changes in the environment, connected with solar activity. A brief description of the optical apparatus of the Space Solar Patrol (SSP) developed and built in the framework of the ISTC projects 385, 385.2, 1523 and 2500 is given. The SSP is intended for permanent monitoring of spectra and absolute fluxes of soft x-ray and extreme ultraviolet (x-ray/EUV) radiation from the full disk of the Sun which ionizes the upper atmosphere of the Earth. Permanent solar monitoring in the main part of the ionizing radiation spectra 0.8-115 (119) nm does not exist. The apparatus of the SSP was developed in the years 1996-2005 with multiyear experience of developing such apparatus in S I Vavilov State Optical Institute. The basis of this apparatus is the use of unique detectors of ionizing radiation—open secondary electron multipliers, which are 'solar blind' to near UV, visible and IR radiation from the Sun, and new methodology of these solar spectroradiometric absolute measurements. The prospects are discussed of using the SSP data for the investigation and forecast of the influence of solar variability on the weather and climate including global warming and also on the biosphere including human beings (proposal 3878). This article was originally submitted for inclusion with the papers from the 9th International Symposium on Measurement Science and Intelligent Instruments (ISMTII-2009), published in the May 2010 issue.

Avakyan, S. V.; Baranova, L. A.; Leonov, N. B.; Savinov, E. P.; Voronin, N. A.

2010-08-01

331

Impact of land surface processes on the South American warm season climate  

NASA Astrophysics Data System (ADS)

The present study demonstrates that (1) the simulation of the South American warm season (December-February) climate by an atmospheric general circulation model (AGCM) is sensitive to the representation of land surface processes, (2) the sensitivity is not confined to the "hot spot" in Amazonia, and (3) upgrading the representation of those processes can produce a significant improvement in AGCM performance. The reasons for sensitivity and higher success are investigated based on comparisons between observational datasets and simulations by the AGCM coupled to either a simple land scheme that specifies soil moisture availability or to the Simplified Simple Biosphere Model (SSiB) that allows for consideration of soil and vegetation biophysical process. The context for the study is the UCLA AGCM. The most notable simulation improvements are along the lee of the Andes in the lower troposphere, where poleward flow transports abundant moisture from the Amazon basin to high latitudes, and in the monsoon region where the intensity and pattern of precipitation and upper level ice water content are more realistic. It is argued that a better depiction of the Chaco Low, which is controlled by local effects of land surface processes, decisively contributes to the superior model performance with low-level flows in central South America. The better representation of the atmospheric column static stability and large-scale moisture convergence in tropical South America contribute to more realistic precipitation over the monsoon region. The overall simulation improvement is, therefore, due to a combination of different regional processes. This finding is supported by idealized AGCM experiments.

Ma, H.-Y.; Mechoso, C. R.; Xue, Y.; Xiao, H.; Wu, C.-M.; Li, J.-L.; de Sales, F.

2011-07-01

332

Energy and global warming impacts of next generation refrigeration and air conditioning technologies  

SciTech Connect

Significant developments have occurred in hydrofluorocarbon (HFC) and the application of ammonia and hydrocarbons as refrigerant working fluids since the original TEWI (Total Equivalent Warming Impact) report in 1991. System operating and performance data on alternative refrigerants and refrigeration technologies justify and updated evaluation of these new alternative refrigerants and competing technologies in well-characterized applications. Analytical and experimental results are used to show quantitative comparisons between HFCS, HFC blends, hydrocarbons, and ammonia, used as refrigerants. An objective evaluation is presented for commercial and near commercial non-CFC refrigerants/blowing agents and alternative refrigeration technologies. This information is needed for objective and quantitative decisions on policies addressing greenhouse gas emissions from refrigeration and air conditioning equipment. The evaluation assesses the energy use and global warming impacts of refrigeration and air conditioning technologies that could be commercialized during the phase out of HCFCS. Quantitative comparison TEWI for two application areas are presented. Opportunities for significant reductions in TEWI are seen with currently known refrigerants through improved maintenance and servicing practices and improved product designs.

Sand, J.R.; Fischer, S.K.; Baxter, V.D.

1996-10-01

333

Effects of excess ground ice on projections of permafrost in a warming climate  

NASA Astrophysics Data System (ADS)

In permafrost soils, ‘excess ice’, also referred to as ground ice, exists in amounts exceeding soil porosity in forms such as ice lenses and wedges. Here, we incorporate a simple representation of excess ice in the Community Land Model (CLM4.5) to investigate how excess ice affects projected permafrost thaw and associated hydrologic responses. We initialize spatially explicit excess ice obtained from the Circum-Arctic Map of Permafrost and Ground-Ice Conditions. The excess ice in the model acts to slightly reduce projected soil warming by about 0.35 °C by 2100 in a high greenhouse gas emissions scenario. The presence of excess ice slows permafrost thaw at a given location with about a 10 year delay in permafrost thaw at 3 m depth at most high excess ice locations. The soil moisture response to excess ice melt is transient and depends largely on the timing of thaw with wetter/saturated soil moisture conditions persisting slightly longer due to delayed post-thaw drainage. Based on the model projections of excess ice melt, we can estimate spatially explicit gridcell mean surface subsidence with values ranging up to 0.5 m by 2100 depending on the initial excess ice content and the extent of melt.

Lee, Hanna; Swenson, Sean C.; Slater, Andrew G.; Lawrence, David M.

2014-12-01

334

Fungal Diversity in Permafrost and Tallgrass Prairie Soils under Experimental Warming Conditions  

PubMed Central

Soil fungi play a major role in terrestrial ecosystem functioning through interactions with soil structure, plants, micro- and mesofauna, and nutrient cycling through predation, pathogenesis, mutualistic, and saprotrophic roles. The diversity of soil fungi was assessed by sequencing their 28S rRNA gene in Alaskan permafrost and Oklahoma tallgrass prairie soils at experimental sites where the effect of climate warming is under investigation. A total of 226,695 reads were classified into 1,063 genera, covering 62% of the reference data set. Using the Bayesian Classifier offered by the Ribosomal Database Project (RDP) with 50% bootstrapping classification confidence, approximately 70% of sequences were returned as “unclassified” at the genus level, although the majority (?65%) were classified at the class level, which provided insight into these lesser-known fungal lineages. Those unclassified at the genus level were subjected to BLAST analysis against the ARB-SILVA database, where ?50% most closely matched nonfungal taxa. Compared to the more abundant sequences, a higher proportion of rare operational taxonomic units (OTU) were successfully classified to genera at 50% bootstrap confidence, indicating that the fungal rare biosphere in these sites is not composed of sequencing artifacts. There was no significant effect after 1 year of warming on the fungal community structure at both sites, except perhaps for a few minor members, but there was a significant effect of sample depth in the permafrost soils. Despite overall significant community structure differences driven by variations in OTU dominance, the prairie and permafrost soils shared 90% and 63% of all fungal sequences, respectively, indicating a fungal “seed bank” common between both sites. PMID:24014534

StLouis, Derek; Cole, James R.; Luo, Yiqi; Wu, Liyou; Schuur, E. A. G; Zhou, Jizhong; Tiedje, James M.

2013-01-01

335

Potential increase of flood hazards in Korea due to global warming from a high-resolution regional climate simulation  

NASA Astrophysics Data System (ADS)

Because of the importance of the changes in the hydrologic cycle, accurate assessment of precipitation characteristics is essential to understand the impact of climate change due to global warming. This study investigates the changes in extreme precipitation with sub-daily and daily temporal scales. For a fine-scale climate change projection focusing on the Korean peninsula (20 km), we performed the dynamical downscaling of the global climate scenario covering the period 1971-2000 (130-year) simulated by the Max-Planck-Institute global climate model, ECHAM5, using the latest version of the International Centre for Theoretical Physics (ICTP) regional climate model, RegCM3. While annual mean precipitation exhibits a pronounced interannual and interdecadal variability, with the increasing or decreasing trend repeated during a certain period, extreme precipitation with sub-daily and daily temporal scales estimated from the generalized extreme value distribution shows consistently increasing pattern. The return period of extreme precipitation is significantly reduced despite the decreased annual mean precipitation at the end of 21st century. The decreased relatively weak precipitation is responsible for the decreased total precipitation, so that the decreased total precipitation does not necessarily mean less heavy precipitation. Climate change projection based on the ECHAM5-RegCM3 model chain clearly shows the effect of global warming in increasing the intensity and frequency of extreme precipitation, even without significantly increased total precipitation, which implies an increased risk for flood hazards. [Acknowledgements] This work was supported by a grant (code#3100-3136-442) funded by the National Institute of Meteorological Research (NIMR), the Korea Meteorological Administration (KMA).

Im, E.-S.; Kwon, J.-H.; Lee, B.-J.; In, S.-R.; Han, S.-O.

2012-04-01

336

Possible impacts of climatic warming scenarios on water resources in the Saskatchewan River Subbasin, Canada  

Microsoft Academic Search

Regional scale studies of the impacts of global warming scenarios provide a useful mechanism for identifying potential regional sensitivities, data gaps and research needs, and for raising awareness of the global warming issue at the regional level. Thus, a pilot study of water resources in the Saskatchewan River Sub-basin was undertaken in order to provide first-cut estimates of impacts in

Stewart J. Cohen

1991-01-01

337

Recent observations of warming in the North Pacific: Is this evidence of anthropogenic climate change?  

Microsoft Academic Search

A transbasin survey of the North Pacific Ocean in 2004 reveals sizable warming of the upper ocean. Temperature observations from the 2004 CLIVAR P2 occupation along 30 degrees north are compared with 1994 WOCE occupation of the same line. The greatest observed warming (about 0.5 C) is observed in the lower ventilated layers of the subtropical thermocline. Analysis of the

P. E. Robbins; J. Swift; R. Fine; A. Thurnherr; D. Min

2004-01-01

338

Climatic warming changes plant photosynthesis and its temperature dependence in a temperate steppe of northern China  

Microsoft Academic Search

Warming responses of photosynthesis and its temperature dependence in two C3 grass (Agropyron cristatum, Stipa krylovii), one C4 grass (Pennisetum centrasiaticum), and two C3 forb (Artemisia capillaris, Potentilla acaulis) species in a temperate steppe of northern China were investigated in a field experiment. Experimental warming with infrared heater significantly increased daily mean assimilation rate (A) in P. centrasiaticum and A.

Shuli Niu; Zhixiong Li; Jianyang Xia; Yi Han; Mingyu Wu; Shiqiang Wan

2008-01-01

339

Climate Change: Sources of Warming in the Late 20th Century  

E-print Network

The role of the North Atlantic Oscillation, the Pacific Decadal Oscillation, volcanic and other aerosols, as well as the extraordinary solar activity of the late 20th century are discussed in the context of the warming since the mid-1970s. Much of that warming is found to be due to natural causes.

Gerald E. Marsh

2009-05-28

340

Climate Change: Sources of Warming in the Late 20th Century  

E-print Network

The role of the North Atlantic Oscillation, the Pacific Decadal Oscillation, volcanic and other aerosols, as well as the extraordinary solar activity of the late 20th century are discussed in the context of the warming since the mid-1970s. Much of that warming is found to be due to natural causes.

Marsh, Gerald E

2009-01-01

341

Modeling hydrological regimes of lakes under climate change conditions using heat-water balance method by Budyko  

NASA Astrophysics Data System (ADS)

Global climate change will lead to increasing air temperatures over the next decades and is expected at least to be 1-2°C above the pre-industrial values in near future. Close relationships between the physical processes in the atmosphere and the surface of the planet cause not only temperature changes, but also changes in other parameters of the climate system including hydrosphere. In this context the investigations of a possible change in moisture regime with global warming are very important for assessment of the future changes in the hydrological cycle. A steady-state hydrological model has been developed for evaluation of the changes in climate and hydrological parameters with the progress of global warming. This model is based on the heat-water balance method by M. Budyko and paleoclimatic scenarios. The Budyko's heat-water balance method is based on the combined solution of energy and water balance equations, as well as two empirical dependences: the evaporation rate on soil water content and the surface runoff on precipitation and soil moisture. This method is a universal one as it was developed using empirical data of different climates, including specific humid and arid ones. The method allows to calculate the mean monthly values of evaporation, runoff and water content of the active soil layer (1 m) using data on mean monthly values of surface air temperature, air humidity, precipitation, cloudiness, surface albedo and solar radiation, both for the actual climatic conditions, and for climatic conditions different from the present ones. Some additional assumptions have been made to adapt the method for scenarios of climate change. The paleoclimate scenarios are considered to a certain extent as analogs of future climates. The scenarios used consist of regional deviation from actual climate of annual precipitation, winter and summer air temperatures for Holocene optimum (6-5 KA B.P.) and Last Interglacial (about 125 KA B.P.), which correspond to global temperature increase by 1° and 2°C, respectively. The results are presented by maps of annual runoff, evaporation, seasonal soil moisture in 1-meter soil layer, duration of snow cover and warm period changes with the progress of global warming for the Northern Hemisphere. The obtained mean values of potential evaporation and evaporation (monthly, seasonal, annual), runoff (annual) have been compared with observed data. The comparison show good agreement. Deviation from annual potential evaporation, evaporation is about 8-10%. The obtained climate change signals have been used for the assessment of the lakes level change with global warming by 1°C and 2°C. Two shallow lakes in different climates have been examined: Lake Neusiedler See (Austria) and Lake Ilmen (Russia). According to the results the water level of Lake Ilmen would be a little lower then current mean annual and it should not significantly change for Neusiedler See with 1°C warming, but increase by 0.5-1.0 m for both lakes with 2°C global warming.

Lemeshko, Natalia; Eitzinger, Josef; Kubu, Gerhard

2013-04-01

342

Impact of vegetation feedback on the mid-Pliocene warm climate  

NASA Astrophysics Data System (ADS)

Studying the vegetation feedback during warm periods of the past can lead to better understanding of those in the future. In this study, we conducted several simulations to analyze vegetation feedback during the mid-Pliocene warm period. The results indicate that the main features of vegetation change in the mid-Pliocene were a northward shift of needleleaf tree, an expansion of broadleaf tree and shrub, and a northward expansion of grass, as compared to the pre-industrial period. The global annual mean warming ratio caused by vegetation feedback was 12.1%, and this warming ratio was much larger in northern middle and high latitudes. The warming caused by vegetation change was directly related to the surface albedo change and was further amplified by snow/sea ice-albedo feedback.

Zhang, Ran; Jiang, Dabang

2014-11-01

343

Assessing the impacts of extended drought conditions and global warming on groundwater resources in Iowa  

NASA Astrophysics Data System (ADS)

Extended drought conditions that affected much of the U.S. throughout 2012 and continued into 2013 are bringing climate change to the forefront of public attention. Long-term effects of an extended dry spell on groundwater is especially concerning as these resources are essential for meeting drinking water demands, supporting agricultural and industrial activities, and maintaining water levels in rivers and lakes. Thus, the impact of extended drought conditions on the entire hydrologic cycle needs to be well understood to guide future resource and land management decisions. This study aims to explore the impact of extended drought conditions on groundwater resources in a representative Iowa watershed using Regional Climate Model scenarios implemented through HydroGeoSphere, a physically-based, surface water-groundwater model. Estimating the impacts of climate changes on groundwater resources requires representation of the full hydrological system, i.e. the connection between the atmospheric and surface-subsurface processes, in a realistic way. In the HydroGeoSphere model, surface and subsurface flow equations are solved simultaneously, and the interdependence of processes like actual evapotranspiration and recharge is handled explicitly. Using such state-of-the-art modeling tools, we seek to address the consequences of changing climate extremes (that have already been experienced and expected to continue over long periods in the future) on the hydrologic cycle of our pilot study area, the South Fork watershed in north-central Iowa. The results will provide a baseline for investigating mitigation strategies in agricultural practices and water use due to changes in the wet and dry cycles of the regional hydrologic cycle.

Acar, O.; Franz, K.; Simpkins, W. W.

2013-12-01

344

Climate variability during warm and cold phases of the Atlantic Multidecadal Oscillation (AMO) 1871-2008  

NASA Astrophysics Data System (ADS)

An extended reanalysis, a combination of observations and model output, is used to examine the spatial patterns of physical variables associated with the Atlantic Multidecadal Oscillation (AMO) from 1871 to 2008. The results are presented as anomalies during positive and negative phases of the AMO. As in previous studies, during positive (negative) AMO phases the sea surface temperature (SST) is anomalously warm (cold) over most of the North Atlantic, with the exception of the east coast of the United States. The atmospheric patterns, associated with the positive phase of the AMO, include anomalous low pressure over the Atlantic between 20°S and 50°N, cyclonic surface winds around the low, reduced wind speeds over the tropical Atlantic and enhanced precipitation in the eastern tropical Atlantic, with roughly opposite conditions during negative AMO phases. There are, however, substantial differences in the SST and the atmospheric anomalies between periods of the same phase, especially in the extratropics. Correlations between the AMO and air temperature anomalies are positive over much of the globe between 40°S and 50°N, with correlations exceeding 0.6 (~ 95% significance level) over the Maritime Continent and northern rim of the Pacific Ocean. Most of the sea level pressure (SLP) anomalies beyond the Atlantic are not statistically significant.

Alexander, Michael A.; Halimeda Kilbourne, K.; Nye, Janet A.

2014-05-01

345

Design and Build of the Qinghai-Tibet Railway considering the Impacts of Warming Climate and Permafrost  

NASA Astrophysics Data System (ADS)

During the period from 1960 to 2000, an 1°C increase of air temperature has been observed along the Qinghai-Tibet Railway (QTR) traversing 632 km of warm and ice-rich permafrost through the interior of the Qinghai-Tibet Plateau. Correspondingly, mean annual ground temperatures (MAGTs) of warm (>-1 °C) permafrost on average increased about 0.3 to 0.5°C during 1970s-1990, while that of colder permafrost had increased by 0.1 to 0.3°C. During 1996-2004, ground temperatures at the permafrost table were increasing at the rates of 0.01-0.08°C a-1, and the permafrost table was lowering at the rates of 2.6 to 6.6 cm a-1; and the ground temperatures at depths of 6 to 8 m were warming at the rates of 0.02 to 0.05°C a-1. Consequently, the strengths of permafrost as the foundation of the QTR would be weakened if proper engineering measures were not taken. Based on the experiences and lessons learned from the road construction in permafrost regions from Alaska, Canada and Russia, and northeastern China, and taking into consideration of possible climatic warming along the QTR during the next 100 years, the design and construction of the QTR adopted the principle of``cooling the roadbed'' because most of the permafrost along the route is too deep to be thawed, too thermally sensitive to climatic warming and too critical to have appreciable thaw settlements. About 550 km of QTR is in continuous permafrost zone, 82 km is in discontinuous permafrost zone; 275 km is in warm permafrost areas, and 110 km of permafrost is ice-rich. The QTR is designed for safe operations during the next 100 years during which a warming of 2.2 to 2.6°C by 2050 is projected. Without engineering measures to keep ground frozen or maintain the settlement within the acceptable limits, thaw settlement in the foundation soils, and induced environmental instability would threaten the integrity and safety of QTR operation. However, only increasing therma resistance, such as increasing fill thickness or using insulation materials is a passive method of permafrost protection and inadequate to ensure the engineering reliability and long-term stability of foundation soils under a persistent warming climate. Therefore, the design of the QTR has to adopt the principle of active cooling by controlling radiation, convection and conduction through modifying road structures. The measures for controlling radiation include the applications of ligh-color fill materials and side-slope materials, and awnings. The measures fo controlling the convection include air ducts, coarse rock roadbed and sideslope structures, and thermosyphons. The methods for controlling the conduction include insulation materials with strong thermal offsets and sufficient strength and durability, grassing of side slopes. Some of the abovementioned methods are combined to enhance the cooling effect in critical sections with warm and ice rich permafrost. These engineering measures based on extensive field and laboratory scientific experimental and simulation research have been adopted by the design and construction of the QTR. The preliminary results indicate that they have been quite effective in maintaining permafrost table positions and the strength of frozen soils at desired levels and thaw settlements at acceptable limits.

Ma, W.; Jin, H.; Cheng, G.; Wu, Q.; Lai, Y.

2005-12-01

346

Stomatal Oscillations in Orange Trees under Natural Climatic Conditions  

PubMed Central

• Background and Aims Stomatal oscillations have been reported in many plant species, but they are usually induced by sudden step changes in the environment when plants are grown under constant conditions. This study shows that in navel orange trees (Citrus sinensis) pronounced stomatal oscillations occur and persist under natural climatic conditions. • Methods Oscillations in stomatal conductance were measured, and related to simultaneous measurements of leaf water potential, and flow rate of sap in the stems of young, potted plants. Cycling was also observed in soil-grown, mature orchard trees, as indicated by sap flow in stem and branches. • Key Results Oscillations in stomatal conductance were caused by the rapid propagation and synchronization of changes in xylem water potential throughout the tree, without rapid changes in atmospheric conditions. • Conclusions The results show marked stomatal oscillations persisting under natural climatic conditions and underscore the need to discover why this phenomenon is so pronounced in orange trees. PMID:16478765

STEPPE, KATHY; DZIKITI, SEBINASI; LEMEUR, RAOUL; MILFORD, JAMES R.

2006-01-01

347

Temperatures of expired air under varying climatic conditions  

Microsoft Academic Search

Measurements of expiration temperatures were carried out under different climatic conditions. In one series of experiments the ambient air temperature was varied, in another the relative humidity of the ambient air. The temperatures of the ambient air ranged between ?5°C and 30°C and the relative humidity between 10% and 90%. The results reveal a high variability of the expiration temperatures,

P. Höppe

1981-01-01

348

Assessing the Response of Nematode Communities to Climate Change-Driven Warming: A Microcosm Experiment.  

PubMed

Biodiversity has diminished over the past decades with climate change being among the main responsible factors. One consequence of climate change is the increase in sea surface temperature, which, together with long exposure periods in intertidal areas, may exceed the tolerance level of benthic organisms. Benthic communities may suffer structural changes due to the loss of species or functional groups, putting ecological services at risk. In sandy beaches, free-living marine nematodes usually are the most abundant and diverse group of intertidal meiofauna, playing an important role in the benthic food web. While apparently many functionally similar nematode species co-exist temporally and spatially, experimental results on selected bacterivore species suggest no functional overlap, but rather an idiosyncratic contribution to ecosystem functioning. However, we hypothesize that functional redundancy is more likely to observe when taking into account the entire diversity of natural assemblages. We conducted a microcosm experiment with two natural communities to assess their stress response to elevated temperature. The two communities differed in diversity (high [HD] vs. low [LD]) and environmental origin (harsh vs. moderate conditions). We assessed their stress resistance to the experimental treatment in terms of species and diversity changes, and their function in terms of abundance, biomass, and trophic diversity. According to the Insurance Hypothesis, we hypothesized that the HD community would cope better with the stressful treatment due to species functional overlap, whereas the LD community functioning would benefit from species better adapted to harsh conditions. Our results indicate no evidence of functional redundancy in the studied nematofaunal communities. The species loss was more prominent and size specific in the HD; large predators and omnivores were lost, which may have important consequences for the benthic food web. Yet, we found evidence for alternative diversity-ecosystem functioning relationships, such as the Rivets and the Idiosyncrasy Model. PMID:23825552

Gingold, Ruth; Moens, Tom; Rocha-Olivares, Axayácatl

2013-01-01

349

Assessing the Response of Nematode Communities to Climate Change-Driven Warming: A Microcosm Experiment  

PubMed Central

Biodiversity has diminished over the past decades with climate change being among the main responsible factors. One consequence of climate change is the increase in sea surface temperature, which, together with long exposure periods in intertidal areas, may exceed the tolerance level of benthic organisms. Benthic communities may suffer structural changes due to the loss of species or functional groups, putting ecological services at risk. In sandy beaches, free-living marine nematodes usually are the most abundant and diverse group of intertidal meiofauna, playing an important role in the benthic food web. While apparently many functionally similar nematode species co-exist temporally and spatially, experimental results on selected bacterivore species suggest no functional overlap, but rather an idiosyncratic contribution to ecosystem functioning. However, we hypothesize that functional redundancy is more likely to observe when taking into account the entire diversity of natural assemblages. We conducted a microcosm experiment with two natural communities to assess their stress response to elevated temperature. The two communities differed in diversity (high [HD] vs. low [LD]) and environmental origin (harsh vs. moderate conditions). We assessed their stress resistance to the experimental treatment in terms of species and diversity changes, and their function in terms of abundance, biomass, and trophic diversity. According to the Insurance Hypothesis, we hypothesized that the HD community would cope better with the stressful treatment due to species functional overlap, whereas the LD community functioning would benefit from species better adapted to harsh conditions. Our results indicate no evidence of functional redundancy in the studied nematofaunal communities. The species loss was more prominent and size specific in the HD; large predators and omnivores were lost, which may have important consequences for the benthic food web. Yet, we found evidence for alternative diversity–ecosystem functioning relationships, such as the Rivets and the Idiosyncrasy Model. PMID:23825552

Gingold, Ruth; Moens, Tom; Rocha-Olivares, Axayácatl

2013-01-01

350

Implications of global warming for regional climate and water resources of tropical islands: Case studies over Sri Lanka and Puerto Rico  

NASA Astrophysics Data System (ADS)

The IPCC AR4 identifies small islands as particularly vulnerable to climate change. Here we consider the cases of two tropical islands: Sri Lanka in the Indian Ocean and Puerto Rico in the Caribbean. The islands share a predominantly tropical climate with diverse topography and hence significant spatial variability of regional climate. Seasonal variability in temperatures is relatively small, but spatial variations can be large owing to topography. Precipitation mechanisms and patterns over the two islands are different however. Sri Lanka receives a majority of the annual rainfall from the summer and winter monsoons, with convective rainfall dominating in the inter-monsoon period. Rainfall generating mechanisms over Puerto Rico can range from orographic lifting, disturbances embedded in Easterly waves and synoptic frontal systems. Here we compare the projected changes in the regional and seasonal means and extremes of temperature and precipitation over the two islands during the middle of this century with the present conditions. Two 5-year regional climate model runs for each region, representing the present (2006-2010) and future (2056-2060) conditions, are performed using the Weather Research and Forecasting model with the lateral boundary conditions provided using the output from CCSM4 RCP8.5 greenhouse gas emissions pathway simulation from the CMIP5 ensemble. The consequences of global warming for water resources and the overall economy are examined. While both economies have substantial contributions from tourism, there are major differences: The agricultural sector is much more important over Sri Lanka compared to Puerto Rico, while the latter exhibits no recent growth in population or in urbanization trends unlike the former. Policy implications for water sustainability and security are discussed, which highlight how despite the differences, certain lessons learned may generalize across the two relatively small tropical islands, which in turn have diverse economic, infrastructural, and societal constraints.

Mawalagedara, R.; Kumar, D.; Oglesby, R. J.; Ganguly, A. R.

2013-12-01

351

Attribution of soil moisture dynamics - Initial conditions vs. atmospheric forcing and the role of climate change  

NASA Astrophysics Data System (ADS)

The world's climate has started to change more quickly in recent decades and a stronger and faster shift is expected in the future. Even if the public perception is mostly limited to a widespread warming, climate change is a complex phenomenon impacting numerous variables of the climate system in different ways, also depending on time and location. Furthermore, extreme events may change more drastically than the mean climate. There is growing evidence that climate change is mostly man-made. However, it is still a matter of debate to which extent changes of the mean climate but also of particular (extreme) events are due to human impact. These questions are addressed by the growing science of climate attribution. Pointing out the anthropogenic influence on extreme events such as the 2010 Russian heatwave or the 2002 floods in Central Europe may help to support adaptation to climate change. This study investigates soil moisture in Europe in the context of climate change, because of its role as a key variable of the land-climate system and its practical importance for instance to agriculture. To derive soil moisture dynamics from 1984-2007 we use E-OBS forcing data together with SRB radiation data and employ an observation-based approach where soil moisture is computed from a water balance equation in which runoff (normalized with precipitation) and ET (normalized with net radiation) are simple functions of soil moisture. The constant runoff function is prescribed for the whole continent, and the ET function is calibrated using temperature data. After performing a validation of the inferred soil moisture data we use it in order to analyze changes in the likelihood of droughts. Our results show increased drought risk especially in north-eastern Europe and the Mediterranean, whereby the probability of extreme droughts increases stronger as for mild dryness episodes. To assess the potential for drought forecasting we furthermore study the importance of the initial conditions versus the atmospheric forcing for monthly soil moisture variations. We find that initial soil moisture anomalies are overall more important than the forcing, even if less pronounced in summer. Especially in southern Europe we show high drought forecasting potential, whereas the forcing is more important in Central and North-eastern Europe.

Orth, Rene; Seneviratne, Sonia I.

2014-05-01

352

Forecasting conditional climate-change using a hybrid approach  

USGS Publications Warehouse

A novel approach is proposed to forecast the likelihood of climate-change across spatial landscape gradients. This hybrid approach involves reconstructing past precipitation and temperature using the self-organizing map technique; determining quantile trends in the climate-change variables by quantile regression modeling; and computing conditional forecasts of climate-change variables based on self-similarity in quantile trends using the fractionally differenced auto-regressive integrated moving average technique. The proposed modeling approach is applied to states (Arizona, California, Colorado, Nevada, New Mexico, and Utah) in the southwestern U.S., where conditional forecasts of climate-change variables are evaluated against recent (2012) observations, evaluated at a future time period (2030), and evaluated as future trends (2009–2059). These results have broad economic, political, and social implications because they quantify uncertainty in climate-change forecasts affecting various sectors of society. Another benefit of the proposed hybrid approach is that it can be extended to any spatiotemporal scale providing self-similarity exists.

Esfahani, Akbar Akbari; Friedel, Michael J.

2014-01-01

353

Glaciological studies of the evolution of ice sheets in a warming climate.  

NASA Astrophysics Data System (ADS)

The last 10-15 years have witnessed tremendous improvements in our ability to study ice sheets in Antarctica and Greenland, thanks to the advent of satellite missions (ERS-1/2, Radarsat-1, Envisat, GRACE, ICESAT, ALOS, MODIS, ASTER) and the deployment of modern sensors onboard aircrafts (lidar, radar sounder) and on the ground (GPS, seismometer, AWS). Geodesy has been played a central piece in those efforts. As these new tools became available and unveiled unknown details about the present-day status of these ice sheets, the influence of humans started to perturb the system beyond what any of us was ready to accept. In Greenland, we learned in the 1990s that the ice sheet was shrinking as a result of coastal thinning. In the 2000s, we witnessed major glaciological changes that tripled the mass deficit in only 11 years. While these changes only represent a trickle of melt water in the vast oceans, they took place sooner, more rapidly, and more strongly than expected. Following the realization that large-scale models fail to predict this evolution, a race with time began with laser, sounders, InSAR, GPS, seismometer, cameras to determine what causes these glaciers to change so rapidly and what this means for the future. The roles of surface melt water, ice- quakes, calving dynamics, melting of calving faces by warm ocean waters, or sub-glacial hydrology are investigated in more details, ice motion, surface elevation and thickness are mapped at the continental scale with high precision, leaving a frantic trail of exploration and discoveries of how little we knew, and how little we know. In Antarctica, immutable continent far from human influence, we witnessed some of the most spectacular glaciological changes in the wake of the collapse of the Larsen ice shelves. Satellite data reveal that places believed to be vulnerable to climate change and inherently unstable are indeed changing rapidly at present, over large areas. Even East Antarctica is sending eye-opening signs of changes to come. Antarctica remains frantically cold, yet its surrounding ocean is changing, and the ice sheet is responding beyond what numerical or conceptual models anticipated. In this talk, I will attempt to synthesize these advances, the challenges that lay ahead and what the coming century may hold.

Rignot, E.

2008-12-01

354

State of the climate in 2010  

E-print Network

Several large-scale climate patterns influenced climate conditions and weather patterns across the globe during 2010. The transition from a warm El Niño phase at the beginning of the year to a cool La Niña phase by July ...

Ganesan, Anita

355

Permafrost degradation and methane: low risk of biogeochemical climate-warming feedback  

E-print Network

Climate change and permafrost thaw have been suggested to increase high latitude methane emissions that could potentially represent a strong feedback to the climate system. Using an integrated earth-system model framework, ...

Gao, Xiang

356

Climate and hydrographic variability in the Indo-Pacific Warm Pool during the last millennium  

E-print Network

millennium. The warmest temperatures and highest salinities occurred during the Medieval Warm Period (MWP to the end of the nineteenth century [Mann et al., 1999]. Ice cores from both Greenland and Antarctica show

Stott, Lowell

357

The Effects of Urban Warming on Herbivore Abundance and Street Tree Condition  

PubMed Central

Trees are essential to urban habitats because they provide services that benefit the environment and improve human health. Unfortunately, urban trees often have more herbivorous insect pests than rural trees but the mechanisms and consequences of these infestations are not well documented. Here, we examine how temperature affects the abundance of a scale insect, Melanaspis tenebricosa (Comstock) (Hemiptera: Diaspididae), on one of the most commonly planted street trees in the eastern U.S. Next, we examine how both pest abundance and temperature are associated with water stress, growth, and condition of 26 urban street trees. Although trees in the warmest urban sites grew the most, they were more water stressed and in worse condition than trees in cooler sites. Our analyses indicate that visible declines in tree condition were best explained by scale-insect infestation rather than temperature. To test the broader relevance of these results, we extend our analysis to a database of more than 2700 Raleigh, US street trees. Plotting these trees on a Landsat thermal image of Raleigh, we found that warmer sites had over 70% more trees in poor condition than those in cooler sites. Our results support previous studies linking warmer urban habitats to greater pest abundance and extend this association to show its effect on street tree condition. Our results suggest that street tree condition and ecosystem services may decline as urban expansion and global warming exacerbate the urban heat island effect. Although our non-probability sampling method limits our scope of inference, our results present a gloomy outlook for urban forests and emphasize the need for management tools. Existing urban tree inventories and thermal maps could be used to identify species that would be most suitable for urban conditions. PMID:25054326

Dale, Adam G.; Frank, Steven D.

2014-01-01

358

Floodplains, permafrost, cottonwood trees, and peat: What happened the last time climate warmed suddenly in arctic Alaska?  

Microsoft Academic Search

We use the stratigraphy of floodplains on Alaska’s North Slope to describe how tundra watersheds responded to climate changes over the last 15,000 calibrated years BP (15 cal ka BP). Two episodes of extremely rapid floodplain alluviation occurred during the Pleistocene–Holocene transition, one between 14 and 12.8 cal ka BP and the other between 11.5 and 9.5 cal ka BP. These aggradation episodes coincided with periods of warming in

Daniel H. Mann; Pamela Groves; Richard E. Reanier; Michael L. Kunz

2010-01-01

359

Comparing Observed Hurricane Conditions Against Potential Future Climate Change Influences  

NASA Astrophysics Data System (ADS)

Climate Adaptation Science Investigators: (CASI) is to advance and apply NASA's scientific expertise and products to develop climate adaptation strategies that support NASA's overall mission by minimizing risks to each center's operations, physical assets, and personnel. Using Hurricane Katrina observations as a baseline, we use ADCIRC to model surge extent with simple modifications of the storm track. We examine two time now (T0) scenarios of present-day climatological factors: 1) translating the 2005 path 7 km west; and 2) rotating the approach angle from due-north to WNW. Second, we examine two future time scenarios (TX) by infusing climate change conditions, such as sea level rise and increased storm intensity, into a T0 baseline to assess future impacts. The primary goal of this work entails planning and protecting NASA assets and infrastructure. The adjacent communities, state and local emergency managers, gain benefit from this NASA work as data and analysis includes the surrounding geography.

Graham, W. D.

2012-12-01

360

Regression tree modeling of forest NPP using site conditions and climate variables across eastern USA  

NASA Astrophysics Data System (ADS)

As evidence of global warming continue to increase, being able to predict forest response to climate changes, such as expected rise of temperature and precipitation, will be vital for maintaining the sustainability and productivity of forests. To map forest species redistribution by climate change scenario has been successful, however, most species redistribution maps lack mechanistic understanding to explain why trees grow under the novel conditions of chaining climate. Distributional map is only capable of predicting under the equilibrium assumption that the communities would exist following a prolonged period under the new climate. In this context, forest NPP as a surrogate for growth rate, the most important facet that determines stand dynamics, can lead to valid prediction on the transition stage to new vegetation-climate equilibrium as it represents changes in structure of forest reflecting site conditions and climate factors. The objective of this study is to develop forest growth map using regression tree analysis by extracting large-scale non-linear structures from both field-based FIA and remotely sensed MODIS data set. The major issue addressed in this approach is non-linear spatial patterns of forest attributes. Forest inventory data showed complex spatial patterns that reflect environmental states and processes that originate at different spatial scales. At broad scales, non-linear spatial trends in forest attributes and mixture of continuous and discrete types of environmental variables make traditional statistical (multivariate regression) and geostatistical (kriging) models inefficient. It calls into question some traditional underlying assumptions of spatial trends that uncritically accepted in forest data. To solve the controversy surrounding the suitability of forest data, regression tree analysis are performed using Software See5 and Cubist. Four publicly available data sets were obtained: First, field-based Forest Inventory and Analysis (USDA, Forest Service) data set for the 31 eastern most United States. Second, 8-day composite of MODIS Land Cover, FPAR, LAI and GPP/NPP data were obtained from Jan 2001 to Dec 2004 (total 182 composite) and each product were filtered by pixel-level quality assurance data to select best quality pixels. Third, 30-year averaged climate data were collected from National Oceanic and Atmospheric Administration (NOAA) and five climatic variables were obtained: Monthly temperature, precipitation, annual heating and cooling days, and annual frost-free days. Forth, topographic data were obtained from digital elevation model (1km by 1km). This research will provide a better understanding of large-scale forest responses to environmental factors that will be beneficial for the development of important forest management applications.

Kwon, Y.

2013-12-01

361

Random walk expectancies for recent global climate, and in an enhanced Greenhouse warming  

NASA Astrophysics Data System (ADS)

We partition the United Kingdom Meteorological Office Global Temperature Series ( Tk) using an exponential decay filter into a filtered series ( T?k) and a difference series ( T' k = T k - T?k). For a decay time constant, ? ? 0.85 years, T?k is shown to be agood approximation to a random walk generated by a cumulation of normally distributed interannual temperature transitions, and hence ' k contains the predictable temperature signal. The standard deviation of the T?k series, ? = 0.083K, which is about 1 1/2 that of the T' k series. From this partition, it is argued that ? is the decay time costant (e-folding time) for the global temperature series, and also by the elementary theory of damped oscillations, that the global cimate system (as represented by the global temperature) can only support free oscillations of natural period less than T = 2 ?? ? 5 years, i.e. the QBO and ENSO signals. On assuming that ? does not vary significantly over periods up to 20,000 B.P. we find that the expected maximum excursions of the random walks are consistent with the actual inferred temperature variability. On the other hand, the projected temperature rise due to the enhanced Greenhouse effect possibly cannot be supported as a random walk by ?. This suggests that the interannual structure of the climate system would change under these conditions. This conjecture can be tested adequately only with climate models which correctly reproduced random walk behaviour. This is inhibited in published simulated temperature series from coupled models, possibly because of flux correction. An assessment of the likelihood of a change in the interannual variance, and of the ratio between its predictable and random proportions is clearly of utmost significance in the Greenhouse debate, yet it appears to have received very little discussion.

Gordon, Adrian H.; Bye, John A. T.

1993-11-01

362

Weakening and strengthening structures in the Hadley Circulation change under global warming and implications for cloud response and climate sensitivity  

NASA Astrophysics Data System (ADS)

has long been recognized that differences in climate model-simulated cloud feedbacks are a primary source of uncertainties for the model-predicted surface temperature change induced by increasing greenhouse gases such as CO2. Large-scale circulation broadly determines when and where clouds form and how they evolve. However, the linkage between large-scale circulation change and cloud radiative effect (CRE) change under global warming has not been thoroughly studied. By analyzing 15 climate models, we show that the change of the Hadley Circulation exhibits meridionally varying weakening and strengthening structures, physically consistent with the cloud changes in distinct cloud regimes. The regions that experience a weakening (strengthening) of the zonal-mean circulation account for 54% (46%) of the multimodel-mean top-of-atmosphere (TOA) CRE change integrated over 45°S-40°N. The simulated Hadley Circulation structure changes per degree of surface warming differ greatly between the models, and the intermodel spread in the Hadley Circulation change is well correlated with the intermodel spread in the TOA CRE change. This correlation underscores the close interactions between large-scale circulation and clouds and suggests that the uncertainties of cloud feedbacks and climate sensitivity reside in the intimate coupling between large-scale circulation and clouds. New model performance metrics proposed in this work, which emphasize how models reproduce satellite-observed spatial variations of zonal-mean cloud fraction and relative humidity associated with the Hadley Circulation, indicate that the models closer to the satellite observations tend to have equilibrium climate sensitivity higher than the multimodel mean.

Su, Hui; Jiang, Jonathan H.; Zhai, Chengxing; Shen, Tsaepyng J.; Neelin, J. David; Stephens, Graeme L.; Yung, Yuk L.

2014-05-01

363

Is bias correction of Regional Climate Model (RCM) simulations possible for non-stationary conditions?  

NASA Astrophysics Data System (ADS)

Regional Climate Models (RCMs) are commonly used in climate-change impact studies to transfer large-scale Global Climate Model (GCM) values to smaller scales and to provide more detailed regional information. There is, however, the problem that RCM simulations often show considerable deviations from local observations due to systematic and random model errors. This issue has caused the development of several correction approaches, that can be classified according to their degree of complexity and include simple-to-apply methods such as linear transformations but also more advanced methods such as distribution mapping. Most of these common correction approaches are based on the assumption that RCM errors do not change over time. It is in principle not possible to test whether this underlying assumption of error stationarity is actually fulfilled for future climate conditions. In this contribution, however, we show that it is possible to evaluate how well correction methods perform for conditions different from those that they were calibrated to. This can be done with the relatively simple differential split-sample test, originally proposed by Klemeš ["Operational testing of hydrological simulation models", Hydrological Sciences Journal 31, no. 1 (1986): 13-24]. For five Swedish catchments, precipitation and temperature time series from 15 different ERA40-driven RCM simulations were corrected with different commonly-used bias correction methods. We then performed differential split-sample tests by dividing the data series into cold and warm respective dry and wet years. This enabled us to cross-evaluate the performance of different correction procedures under systematically varying climate conditions. The differential split-sample test identified major differences in the ability of the applied correction methods to reduce model errors and to cope with non-stationary biases. More advanced correction methods performed better, whereas large deviations remained for climate model simulations corrected with simpler approaches. Therefore, we question the use of simple correction methods such as the widely used delta-change approach and linear transformation for RCM-based climate-change impact studies. Instead, we recommend using higher-skill correction methods such as distribution mapping.

Teutschbein, Claudia; Seibert, Jan

2014-05-01

364

Energy-balance and circulation controls of consistent large-scale temperature responses in warm and cold climates  

NASA Astrophysics Data System (ADS)

The Coupled Modelling Intercomparison Project Phase 5 (CMIP5), which requires the same version of models for paleo, historical, and future simulations, combined with large-scale paleoclimatic data syntheses (e.g., the Multiproxy Approach for the reconstruction of Glacial Ocean (MARGO) project, and the quantitative climate reconstructions based on the pollen and plant macrofossil data) allow diagnostic analyses of the mechanisms responsible for the large-scale spatial patterns of temperature that consistently occur in simulations of warm and cold climates. Comparison with the large-scale temperature changes shown by historical observations and by paleoclimate reconstructions also allows us to determine the realism of these responses. We have examined temperature responses in several CMIP5 experiments (lgm, midHolocene, historical, 1pctCO2, and abrupt4xCO2), and used six models (IPSL-CM5A-LR, MPI-ESM-P, MIROC-ESM, CCSM4, MRI-CGCM3, and GISS-E2-R). The simulations show major patterns of past and modern climates changes including 1) the differential response of land-ocean to warming/cooling, 2) the tendency for temperature changes in the higher latitudes to be more extreme than changes in the tropics, and 3) the amplification of seasonality in both warmer/cooler climates. The consistency among simulated and observed large-scale temperature responses shows that these are features of the real climate system that are simulated successfully by models. Moreover, consistency in the simulated patterns of past (e.g., lgm) and future (e.g., abrupt4xCO2) temperature changes implies that a small set of common mechanisms controls the response of the climate system across multiple states. In this study, we explore the key controls for the three large-scale temperature responses in both warmer and cooler climates using a simple energy balance model and analyses of atmospheric circulation changes. Overall, across the range of simulations, variations in clear-sky downward longwave radiation are responsible for the patterns in large-scale temperature anomalies, and in the lgm simulation, this mechanism is augmented by surface albedo feedback.

Izumi, K.; Bartlein, P. J.

2013-12-01

365

Sensitivity of salmonid freshwater life history in western US streams to future climate conditions.  

PubMed

We projected effects of mid-21st century climate on the early life growth of Chinook salmon (Oncorhynchus tshawytscha) and steelhead (O. mykiss) in western United States streams. Air temperature and snowpack trends projected from observed 20th century trends were used to predict future seasonal stream temperatures. Fish growth from winter to summer was projected with temperature-dependent models of egg development and juvenile growth. Based on temperature data from 115 sites, by mid-21st century, the effects of climate change are projected to be mixed. Fish in warm-region streams that are currently cooled by snow melt will grow less, and fish in suboptimally cool streams will grow more. Relative to 20th century conditions, by mid-21st century juvenile salmonids' weights are expected to be lower in the Columbia Basin and California Central Valley, but unchanged or greater in coastal and mountain streams. Because fish weight affects fish survival, the predicted changes in weight could impact population fitness depending on other factors such as density effects, food quality and quantity changes, habitat alterations, etc. The level of year-to-year variability in stream temperatures is high and our analysis suggests that identifying effects of climate change over the natural variability will be difficult except in a few streams. PMID:23640715

Beer, W Nicholas; Anderson, James J

2013-08-01

366

The anxieties of a science diplomat: field coproduction of climate knowledge and the rise and fall of Hans Ahlmann's polar warming".  

PubMed

In the decades between the world wars there were several attempts to document and explain perceived tendencies of atmospheric warming. Hans Ahlmann, a seminal figure in modern glaciology and a science policy adviser and diplomat, constructed a theory of "polar warming" using field results from glacier melting in the Arctic. This article aims to link the rise and fall of "polar warming" with Ahlmann's style of fieldwork. In Ahlmann's view, fieldwork should (1) enhance credibility of polar climate science by emulating laboratory methods and (2) secure knowledge in remote places through collaboration with local residents and fieldworkers. The bodily nature of this style of knowledge production turned out to be an asset in establishing Ahlmann's theory of polar warming but ultimately proved nonresilient to theories of anthropogenic climate change, which became influential from the 1950s onward. PMID:21936187

Sörlin, Sverker

2011-01-01

367

Premonsoon Aerosol Characterization and Radiative Effects Over the Indo-Gangetic Plains: Implications for Regional Climate Warming  

NASA Technical Reports Server (NTRS)

The Himalayas have a profound effect on the South Asian climate and the regional hydrological cycle, as it forms a barrier for the strong monsoon winds and serves as an elevated heat source, thus controlling the onset and distribution of precipitation during the Indian summer monsoon. Recent studies have suggested that radiative heating by absorbing aerosols, such as dust and black carbon over the Indo-Gangetic Plains (IGP) and slopes of the Himalayas, may significantly accelerate the seasonal warming of the Hindu Kush-Himalayas-Tibetan Plateau (HKHT) and influence the subsequent evolution of the summer monsoon. This paper presents a detailed characterization of aerosols over the IGP and their radiative effects during the premonsoon season (April-May-June) when dust transport constitutes the bulk of the regional aerosol loading, using ground radiometric and spaceborne observations. During the dust-laden period, there is a strong response of surface shortwave flux to aerosol absorption indicated by the diurnally averaged forcing efficiency of -70 W/sq m per unit optical depth. The simulated aerosol single-scattering albedo, constrained by surface flux and aerosol measurements, is estimated to be 0.89+/- 0.01 (at approx.550 nm) with diurnal mean surface and top-of-atmosphere forcing values ranging from -11 to -79.8 W/sq m and +1.4 to +12 W/sq m, respectively, for the premonsoon period. The model-simulated solar heating rate profile peaks in the lower troposphere with enhanced heating penetrating into the middle troposphere (5-6 km), caused by vertically extended aerosols over the IGP with peak altitude of approx.5 km as indicated by spaceborne Cloud-Aerosol Lidar with Orthogonal Polarization observations. On a long-term climate scale, our analysis, on the basis of microwave satellite measurements of tropospheric temperatures from 1979 to 2007, indicates accelerated annual mean warming rates found over the Himalayan-Hindu Kush region (0.21 C/decade+/-0.08 C/decade) and underscores the potential role of enhanced aerosol solar absorption in the maximum warming localized over the western Himalayas (0.26 C/decade f 0.09 C/decade) that significantly exceed the entire HKHT and global warming rates. We believe the accelerated warming rates reported here are critical to both the South Asian summer monsoon and hydro-glaciological resource variability in the Himalayan-Hindu Kush snowpack and therefore to the densely populated downstream regions.

Gautam, Ritesh; Hsu, N. Christina; Lau, K.-M.

2010-01-01

368

Gross mismatch between thermal tolerances and environmental temperatures in a tropical freshwater snail: Climate warming and evolutionary implications.  

PubMed

The relationship between acute thermal tolerance and habitat temperature in ectotherm animals informs about their thermal adaptation and is used to assess thermal safety margins and sensitivity to climate warming. We studied this relationship in an equatorial freshwater snail (Clea nigricans), belonging to a predominantly marine gastropod lineage (Neogastropoda, Buccinidae). We found that tolerance of heating and cooling exceeded average daily maximum and minimum temperatures, by roughly 20°C in each case. Because habitat temperature is generally assumed to be the main selective factor acting on the fundamental thermal niche, the discordance between thermal tolerance and environmental temperature implies trait conservation following 'in situ' environmental change, or following novel colonisation of a thermally less-variable habitat. Whereas heat tolerance could relate to an historical association with the thermally variable and extreme marine intertidal fringe zone, cold tolerance could associate with either an ancestral life at higher latitudes, or represent adaptation to cooler, higher-altitudinal, tropical lotic systems. The broad upper thermal safety margin (difference between heat tolerance and maximum environmental temperature) observed in this snail is grossly incompatible with the very narrow safety margins typically found in most terrestrial tropical ectotherms (insects and lizards), and hence with the emerging prediction that tropical ectotherms, are especially vulnerable to environmental warming. A more comprehensive understanding of climatic vulnerability of animal ectotherms thus requires greater consideration of taxonomic diversity, ecological transition and evolutionary history. PMID:25526660

Polgar, Gianluca; Khang, Tsung Fei; Chua, Teddy; Marshall, David J

2015-01-01

369

Predicting the impact of climatic warming on the carbon balance of the moss Sanionia uncinata on a maritime Antarctic island.  

PubMed

The effects of climatic factors, especially those of temperature, on the carbon balance of the moss Sanionia uncinata were examined on King George Island in the maritime Antarctic. Net photosynthesis (P(n)) and dark respiration rates of two colonies (A and B) were measured with a portable infrared gas analyzer. Colony A showed small P(n) compared with its dark respiration rates throughout the growing season. Colony B showed much higher net photosynthetic rates, but the dark respiration rates of the two colonies did not differ significantly. Net photosynthetic rate determined at light saturation was almost constant over a wide temperature range, from 5 degrees to 15 degrees C, while the dark respiration was strongly affected by temperature. To assess the impact of warming on the carbon balance of the moss, cumulative carbon gain of the moss was calculated using a simulation model for the main part of the growing season. The results suggest that climatic warming may cause a reduction of carbon gain in some relatively photosynthetically inactive moss colonies. PMID:12884132

Nakatsubo, Takayuki

2002-04-01

370

Responses in leaf functional traits and resource allocation of a dominant alpine sedge ( Kobresia pygmaea ) to climate warming in the Qinghai-Tibetan Plateau permafrost region  

Microsoft Academic Search

Assessing the influence of warming on leaf traits, carbon, and nutrient concentrations above and below ground to understand\\u000a how the dominant sedge Kobresia pygmaea (C. B. Clarke) C. B. Clarke may respond and adapt to extant and future climate in the alpine meadow of the Qinghai-Tibetan\\u000a Plateau. A warming experiment was conducted in the permafrost region of the Qinghai-Tibetan Plateau

Yan Yang; Genxu Wang; Kari Klanderud; Liudong Yang

371

Recent observations of warming in the North Pacific: Is this evidence of anthropogenic climate change?  

NASA Astrophysics Data System (ADS)

A transbasin survey of the North Pacific Ocean in 2004 reveals sizable warming of the upper ocean. Temperature observations from the 2004 CLIVAR P2 occupation along 30 degrees north are compared with 1994 WOCE occupation of the same line. The greatest observed warming (about 0.5 C) is observed in the lower ventilated layers of the subtropical thermocline. Analysis of the transient tracers concentrations offers a temporal diagnostic of the characteristic renewal time of the ventilated water masses. Chloroflourocarbon measurements collected on the 2004 CLIVAR P2 cruise show that the water masses with the greatest observed temperature increases are those with ventilation time scales of a decade to a century.

Robbins, P. E.; Swift, J.; Fine, R.; Thurnherr, A.; Min, D.

2004-12-01

372

Response to CO2 Transient Increase in the GISS Coupled Model: Regional Coolings in a Warming Climate  

NASA Technical Reports Server (NTRS)

The (GISS) Goddard Institute for Space Studies coupled atmosphere-ocean model is used to investigate the effect of increased atmospheric CO2 by comparing a compounded 1 percent CO2 increase experiment with a control simulation. After 70 years of integration, the global surface air temperature in the 1 percent CO2 experiment is 1.43 C warmer. In spite of this global warming, there are two distinct regions, the northern Atlantic Ocean and the southern Pacific Ocean, where the surface air temperature is up to 4 C cooler. This situation is maintained by two positive feedbacks: a local effect on convection in the South Pacific and a non-local impact on the meridional circulation in the North Atlantic. The poleward transport of latent energy and dry static energy by the atmosphere is greater in the 1 percent CO2 experiment, caused by warming and therefore increased water vapor and greater greenhouse capacity at lower latitudes. The larger atmospheric transports tend to reduce upward vertical fluxes of heat and moisture from the ocean surface at high latitudes, which has the effect of stabilizing the ocean, reducing both convection and the thermohaline circulation. With less convection, less warm water is brought up from below, and with a reduced North Atlantic thermohaline circulation (by 30 percent at time of CO2 doubling), the poleward energy transport by the oceans decreases. The colder water then leads to further reductions in evaporation, decreases of salinity at high latitudes, continued stabilization of the ocean, and maintenance of reduced convection and meridional overturning. Although sea ice decreases globally, it increases in the cooling regions which reduces the overall climate sensitivity; its effect is most pronounced in the Southern Hemisphere. Tropical warming has been observed over the past several decades; if modeling studies such as this and others which have produced similar effects are valid, these processes may already be beginning.

Russell, Gary L.; Rind, David

1999-01-01

373

Response to CO{sub 2} transient increase in the GISS coupled model: Regional coolings in a warming climate  

SciTech Connect

The GISS coupled atmosphere-ocean model is used to investigate the effect of increased atmospheric CO{sub 2} by comparing a compounded 1% CO{sub 2} increase experiment with a control simulation. After 70 yr of integration, the global surface air temperature in the 1% CO{sub 2} experiment is 1.43 C warmer. In spite of this global warming, there are two distinct regions, the northern Atlantic Ocean and the southern Pacific Ocean, where the surface air temperature is up to 4 C cooler. This situation is maintained by two positive feedbacks: a local effect on convection in the South Pacific and a nonlocal impact on the meridional circulation in the North Atlantic. The poleward transport of latent energy and dry static energy by the atmosphere is greater in the 1% CO{sub 2} experiment, caused by warming and therefore increased water vapor and greater greenhouse capacity at lower latitudes. The larger atmospheric transports tend to reduce upward vertical fluxes of heat and moisture from the ocean surface at high latitudes, which has the effect of stabilizing the ocean, reducing both convection and the thermohaline circulation. With less convection, less warm water is brought up from below, and with a reduced North Atlantic thermohaline circulation, the poleward energy transport by the oceans decreases. The colder water then leads to further reductions in evaporation, decreases of salinity at high latitudes, continued stabilization of the ocean, and maintenance of reduced convection and meridional overturning. Although sea ice decreases globally, it increases in the cooling regions, which reduces the overall climate sensitivity, especially in the Southern Hemisphere. Tropical warming has been observed over the past several decades; if modeling studies such as this and others that have produced similar effects are valid, these processes may already be beginning.

Russell, G.L.; Rind, D. [NASA/Goddard Space Flight Center, New York, NY (United States). Inst. for Space Studies] [NASA/Goddard Space Flight Center, New York, NY (United States). Inst. for Space Studies

1999-02-01

374

Climate conditions in Sweden in a 100,000 year time perspective  

E-print Network

Climate conditions in Sweden in a 100,000 year time perspective Jenny Brandefelt, Erik Kjellström including variations in the climate. In a 100,000-year time frame, climate conditions in Sweden may change climate model (RCA3). Reports Meteorology and Climatology, 108, SMHI, SE-60176 Norrköping, Sweden, 54 pp

Brandefelt, Jenny

375

How the West Was Warmed  

NASA Astrophysics Data System (ADS)

Is the West getting warmer? To be sure, the summer of 2005 was one of record heat in the West, and recent period of western US drought during 1998-2004 was also accompanied by unusual warmth. But warm conditions accompanied the Dust Bowl era of the 1930s and the 1950s. The question remains open whether recent western warming has been part of a externally forced climate trend, or whether other processes have been at play like urbanization or the inherent natural fluctuations of climate paterns? We perform analysis of the Fourth Assessment coupled ocean-atmosphere models for the period 1895-2005, together with atmospheric general circulation model experiments. These reveal that the recent warming of the West has very likely been a consequence of increasing greenhouse gases. In fact, no single member of 40 availabl GHG-forced simulations failed to warm the West during the past century. We further show that a warming of the tropical oceanic warm pool regions, itself a greenhouse gas forced response, has been a major contributor to the warming of the West since 1970.

Hoerling, M.; Eischeid, J.

2006-05-01

376

Relationship between solar irradiance and climatic variability in the subpolar North Atlantic since the Medieval Warm Period  

NASA Astrophysics Data System (ADS)

The potential role of solar irradiance as a climate forcing during the Medieval Warm Period (MWP)-Little Ice Age (LIA)-20th Century interval can be tested using several proxies. In this work we use the occurrence of fine sand sized lithic grains (63-150 ?m) in North Atlantic marine sediments to study the climatic history of high latitudes because these lithic grains were ice-rafted either by icebergs or sea-ice. The Holocene ice-rafted debris (IRD) flux is much lower than the IRD flux during glacial periods but the occurrence of hematite-stained grains (HSG) from Paleozoic red beds, Icelandic volcanic glass, and detrital carbonate in the fine sand fraction has been used to track climatic variability at several North Atlantic areas: Feni Drift off Ireland, off eastern Greenland near Denmark Strait, and off Newfoundland (Bond et al, 2001). This controversial work suggested that during the Holocene major ice-rafting discharges matched solar irradiance variability patterns inferred from cosmogenic nuclides (10Be fluxes measured in Greenland ice cores and 14C records from tree rings) and hence, variations in the solar output may have paced centennial- to millennial-scale climate variability in the North Atlantic region. Since 2001 improved 10Be and 14C records have been released and several new sedimentological studies of subpolar North Atlantic marine sites suggested that other climatic forcings may have been involved in Holocene climate variability rather than solar activity (e.g. Moros et al., 2006; Andrews et al., 2009). Moreover, even the ice-rafted origin of the debris has been questioned at some sites. Here we present new high resolution North Atlantic IRD records from Denmark Strait off eastern Greenland and the Labrador Sea, in addition to recounts of sites on the Feni Drift off Ireland (Bond et al., 2001), to study climate variability in the subpolar North Atlantic since MWP. IRD counts are performed using the same technique as in Bond et al. (2001) to (1) replicate Bond's techniques in the same samples/cores, (2) evaluate the coherence of the climate variability across the North Atlantic, and (3) compare these techniques with other IRD proxies such as x-ray diffraction (XRD) records. Furthermore, statistical and time series analyses will be conducted on the IRD concentration record and relative abundances of HSG and volcanic fragments to study the possible cyclicity of increases in icebergs/sea-ice export. The comparison of these IRD records with the new 10Be and 14C records will shed light on the possible linkage between variations in solar irradiance and climate changes that took place during the last ~1000 years, particularly during the LIA.

Alonso-Garcia, M.; Flower, B. P.; Kleiven, H. F.; Andrews, J. T.

2011-12-01

377

MODELING THE POTENTIAL CHANGE IN YIELD AND DISTRIBUTION OF THE EARTH'S CROPS UNDER A WARMED CLIMATE  

EPA Science Inventory

The large scale distribution of crops is largely determined by climate. e present the results of a climate-crop prediction model based on the U.S. Food & Agriculture Organization crop-suitability approach, implemented in a geographic information system(GIS) environment using seve...

378

Reproductive and physiological responses to simulated climate warming for four subalpine species  

Microsoft Academic Search

Summary • The carbon costs of reproduction were examined in four subalpine herbaceous plant species for which number and size of flowers respond differently under a long- term infrared warming experiment. • Instantaneous measurements of gas exchange and an integrative model were used to calculate whole-plant carbon budgets and reproductive effort (RE). • Of the two species for which flowering

Susan C. Lambrecht; Michael E. Loik; David W. Inouye; John Harte

2007-01-01

379

Climate of Concern--A Search for Effective Strategies for Teaching Children about Global Warming  

ERIC Educational Resources Information Center

Recent research suggests that the issue of global warming is one of great concern for Australian children. This point to the need for effective teaching about this issue. Children should be properly informed about actions that help reduce carbon emissions as this may give them a sense of empowerment and go some way to alleviating concerns. This…

Taber, Fiona; Taylor, Neil

2009-01-01

380

Long-term soil warming and Carbon Cycle Feedbacks to the Climate System  

SciTech Connect

The primary objective of the proposed research was to quantify and explain the effects of a sustained in situ 5oC soil temperature increase on net carbon (C) storage in a northeastern deciduous forest ecosystem. The research was done at an established soil warming experiment at the Harvard Forest in central Massachusetts – Barre Woods site established in 2001. In the field, a series of plant and soil measurements were made to quantify changes in C storage in the ecosystem and to provide insights into the possible relationships between C-storage changes and nitrogen (N) cycling changes in the warmed plots. Field measurements included: 1) annual woody increment; 2) litterfall; 3) carbon dioxide (CO2) efflux from the soil surface; 4) root biomass and respiration; 5) microbial biomass; and 6) net N mineralization and net nitrification rates. This research was designed to increase our understanding of how global warming will affect the capacity of temperate forest ecosystems to store C. The work explored how soil warming changes the interactions between the C and N cycles, and how these changes affect land-atmosphere feedbacks. This core research question framed the project – What are the effects of a sustained in situ 5oC soil temperature increase on net carbon (C) storage in a northeastern deciduous forest ecosystem? A second critical question was addressed in this research – What are the effects of a sustained in situ 5{degrees}C soil temperature increase on nitrogen (N) cycling in a northeastern deciduous forest ecosystem?

Melillo, Jerry M.

2014-04-30