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1

The global climate for September-November 1991: Warm (ENSO) episode conditions strengthen  

SciTech Connect

After an extended period of warm episode-like conditions in the western tropical Pacific, ENSO conditions began affecting the central and eastern tropical Pacific during September through November (SON) 1991. The increased convection in the regions of positive SST anomalies provided solid evidence of atmospheric-oceanic coupling, critical in ENSO development and sustenance. In the midlatitudes, the most pronounced climatic feature during SON 91 was the preponderance of above-normal land surface temperatures throughout much of the Northern Hemisphere. 11 refs., 24 figs., 1 tab.

Janowiak, J.E. (NWS/NMC/NOAA, Washington, DC (United States))

1993-08-01

2

Warm climate surprises  

SciTech Connect

Over the last decade, paleoclimatic data from ice cores and sediments have shown that the climate system is capable of switching between significantly different modes, suggesting that climatic surprises may lie ahead. Most attention in the growing area of abrupt climatic change research continues to be focused on large changes observed during glacial periods. The weight of paleoclimatic evidence now suggests that conforting conclusions of benign warm climate variability may be incorrect. The article goes on to discuss the evidence for this. 17 refs.

Overpeck, J.T. [National Geophysical Data Center, Boulder, CO (United States)

1996-03-29

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

Warm Climates in Earth History  

NASA Astrophysics Data System (ADS)

The study of greenhouse climates in the earth's past leads to a greater understanding of the factors that influence today's climate. In this fully integrated volume, leading experts in paleoclimatology present cutting edge paleontological, geological, and theoretical research to assess intervals of global warmth. Coverage examines warm climate intervals during the Paleozoic, Mesozoic and Cenozoic from the same perspectives: oceanic and terrestrial, theoretical and observational. This approach illuminates the differences and, more importantly, the commonalities of warm climate intervals. The book also provides a comprehensive overview of the advantages and limitations of different types of climate models that are currently used, and it discusses major factors that have caused global climatic change across geologic time scales. Central problems that remain unresolved are clearly identified. The book will be of great interest to researchers in paleoclimatology, and it will also be useful as a supplementary text in advanced undergraduate or graduate level courses in paleoclimatology and earth science.

Huber, Brian T.; MacLeod, Kenneth G.; Wing, Scott L.

1999-12-01

5

Assessment of permafrost conditions under Northern Quebec's airports: an integrative approach for the development of adaptation strategies to climate warming  

NASA Astrophysics Data System (ADS)

Community airports in Nunavik were built between 1984 and 1992 and were designed by using a thick embankment of rock fill placed on undisturbed ground surface to prevent the thawing of the underlying permafrost. However, since around 2000, many of the runways show signs of permafrost disturbance as some localized differential settlements have begun to take place. With the anticipated rise of air temperature, the vulnerability of transportation infrastructures to permafrost degradation raises concerns. Several studies initiated by MTQ were undertaken by CEN to evaluate the permafrost conditions underneath airports. These studies provide valuable baseline information but also reveal the needs for a better understanding of the spatial variability of the surficial deposits, their geotechnical properties and permafrost conditions underneath embankments to assess its sensibility to thawing and to plan adaptation strategies in face of climate warming. A geomorphological and geotechnical investigation campaign, including surficial geology mapping using pre-construction air photographs and recovery of drilled frozen cores, was carried out in the summers 2008 and 2009 at eight airports. The impact of the runway embankments on surface drainage, snow drift accumulation and permafrost thawing was also determined. Stratigraphic information from drilling was used to reinterpret CCR and GPR surveys done in previous studies. High resolution cross-sections of the stratigraphy and permafrost conditions could then be drawn. Lab testing over undisturbed frozen samples was performed to determine the geotechnical properties of the different stratigraphic units encountered, particularly thaw consolidation ratios. Field measurements of ground temperatures and numerical modeling of the thermal regime of the embankment and subgrade were also performed to assess the potential impacts on permafrost stability alongside and beneath embankments under different climate change scenarios. Thermistor readings show that the active layer in the central part of the runways is in most case still contained in the embankment or within the prior-to-construction consolidated active layer. However, a residual thaw layer (talik) is now present at the toe of embankments where significant snow accumulations occurred. Thermal modeling indicates that water accumulation and seepage as well as snow accumulation along embankment shoulders are currently the dominant factors of permafrost degradation. In the future, centerlines of embankment built on ice rich permafrost will gradually settle as the climate warms up; therefore periodic reloading will be necessary. To counter permafrost degradation alongside runways and access roads, the proposed mitigation strategies focus on minimizing snow and water accumulation by making gentler slopes (1:6) and by improving the drainage system to avoid potential seepage through embankments.

L'Hérault, E.; Allard, M.; Doré, G.; Barrette, C.; Verreault, J.; Sarrazin, D.; Doyon, J.; Guimond, A.

2011-12-01

6

Warm Climates in Earth History  

NASA Astrophysics Data System (ADS)

Global warming and global environmental change are two key, inter-related topics that receive near-constant attention in the international press. Why? Because the political agencies that direct national and international economies are reluctant to admit that we may be conducting our own global scale experiment in atmospheric pollution. Perhaps they are right to do so. However, the arguments can only be tested properly by carefully documenting the natural climate system and by comparing recent and predicted future regional and global climate change with high-resolution geologic records of past changes and reorganization in response to climatic forcing. Geologic records on their own, though, are limited in their regional and global application and can only be properly applied to understanding the global climate system by integration with computer models and simulations.

Wilson, Gary

7

Surface thermohaline forcing conditions and the response of the present-day global ocean climate to global warming  

Microsoft Academic Search

I investigate the response of the present-day thermohaline circulation to a greenhouse gas induced global warming under different surface thermohaline conditions in a global Bryan\\/Cox [Bryan, 1969; Cox, 1989] ocean general circulation model with realistic bathymetry and geometry. Initially the model is spun up with surface temperature and salinity relaxed to Levitus [1982] climatologies. The forcing condition for salinity is

Wenju Cai

1996-01-01

8

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

9

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

2002-03-08

10

Shifting suitability for malaria vectors across Africa with warming climates  

Microsoft Academic Search

BACKGROUND: Climates are changing rapidly, producing warm climate conditions globally not previously observed in modern history. Malaria is of great concern as a cause of human mortality and morbidity, particularly across Africa, thanks in large part to the presence there of a particularly competent suite of mosquito vector species. METHODS: I derive spatially explicit estimates of human populations living in

A Townsend Peterson

2009-01-01

11

Impact of climate warming on passive night cooling potential  

Microsoft Academic Search

Night-time ventilation is often seen as a promising passive cooling concept. However, as it requires a sufficiently high temperature difference between ambient air and the building structure, this technique is highly sensitive to changes in climatic conditions. In order to quantify the impact of climate warming on the night-time ventilative cooling potential in Europe, eight representative locations across a latitudinal

N. Artmann; D. Gyalistras; H. Manz; P. Heiselberg

2008-01-01

12

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.

Caballero, Rodrigo; Huber, Matthew

2013-01-01

13

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

PubMed

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

2013-08-05

14

Global Warming - The Science of Climate Change  

NASA Astrophysics Data System (ADS)

Extremely topical over recent years, global warming has been the subject of a huge and growing amount of literature. Current literature however tends to fall into two camps: that which is highly scientific in nature and inaccessible to the average student, and that which is directed to the "lay" reader and lacks detail required by students. This book successfully bridges this gap, prividing an accessible explanation of the physical mechanisms of global warming--discussed within the wider context of climate change.

Drake, Frances

2000-07-01

15

Mediterranean seagrass vulnerable to regional climate warming  

NASA Astrophysics Data System (ADS)

The Mediterranean Sea, one of the regions warming fastest under climate change, harbours lush seagrass (Posidonia oceanica) meadows that form the basis for a key ecosystem in the region. Recent field results have shown that increased maximum annual seawater temperature in the Mediterranean has already led to increased seagrass mortality. Here we project the trajectory of P. oceanica meadows under the warming expected in the western Mediterranean through the twenty-first century to conclude that warming will lead to the functional extinction of P. oceanica meadows by the middle of this century (year 2049+/-10) even under a relatively mild greenhouse-gas emissions scenario. Efforts to alleviate local stresses adding to the loss of P. oceanica meadows will have a limited effect in conserving the meadows under climate change. Efforts to mitigate climate change are urgently needed to preserve this key ecosystem.

Jordà, Gabriel; Marbà, Núria; Duarte, Carlos M.

2012-11-01

16

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

17

Terrestrial Carbon Cycle Feedback to Climate Warming: Experimental Evidence  

Microsoft Academic Search

Global climate modeling has demonstrated that climate warming would stimulate respiratory CO2 release from the terrestrial ecosystems to the atmosphere, which in turn leads to more warming in the climate system. This positive feedback between the climate change and the terrestrial carbon cycle can form a vicious cycle that potentially leads to a dangerous threat to ecosystem functioning and service.

Y. Luo; X. Zhou; R. Sherry

2006-01-01

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.

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

Bering Strait influences climate conditions  

NASA Astrophysics Data System (ADS)

The Atlantic meridional overturning circulation (AMOC) acts as a heat conveyer belt, bringing warm tropical water northward in the Atlantic Ocean and carrying cold dense water back southward. Some studies have suggested that changes in AMOC could result in seesaw-like climate changes between the North Atlantic and North Pacific, in which the North Pacific warms while the North Atlantic cools. In fact, paleoclimate studies have found that such a seesaw effect may have occurred during the Heinrich 1 (H1) event about 15-17.5 thousand years ago. However, global climate conditions are much warmer today than they were during the H1 event. Sea level was much lower during the H1 event, and the Bering Strait, which now connects the North Pacific Ocean to the Arctic Ocean, was closed. Some studies have suggested that AMOC could weaken or even collapse entirely as global climate warms because of anthropogenic influence. Would such AMOC changes lead to the seesaw effect seen during the H1 event?

Balcerak, Ernie

2012-03-01

20

Global assessment of experimental climate warming on tundra ...  

Treesearch

Source: Ecology Letters 15: 164–175 ... In situ warming experiments accelerate climate change on a small scale to forecast responses of local plant communities. ... The response of plant groups to warming often differed with ambient summer ...

21

Climatic Fluctuations in Lithuania Against a Background of Global Warming  

Microsoft Academic Search

An analysis of the climatic fluctuations recorded in Lithuania over the 19–20 centuries suggests that, against a background of global warming, trends of climatic elements changeability have been varying with different seasons of the year: winters and springs have warmed up, precipitation in the cold period of the year has increased, whereas summer and autumn temperatures have changed just insignificantly.

Ar?nas Bukantis

2001-01-01

22

Early-Holocene Climate Change in Beringia: Mediation of Global-Warming Impacts by Regional-Scale Boundary-Condition Changes  

Microsoft Academic Search

The early Holocene transition from glacial to interglacial conditions that occurred ca. 13ka to 10ka in Beringia (eastern Siberia, Alaska, and northwestern Canada) was driven by the amplified seasonal cycle of northern hemisphere insolation and the accompanying changes in global ice volume, atmospheric composition, sea- surface temperature, and sea level. The climate of Beringia also was likely influenced by changes

M. E. Edwards; P. J. Bartlein; S. W. Hostetler; S. L. Shafer; P. M. Anderson; L. B. Brubaker

2006-01-01

23

Experimental evaluation of reproductive response to climate warming in an oviparous skink.  

PubMed

The impact of climate warming on organisms is increasingly being recognized. The experimental evaluation of phenotypically plastic responses to warming is a critical step in understanding the biological effects and adaptive capacity of organisms to future climate warming. Oviparous Scincella modesta live in deeply-shaded habitats and they require low optimal temperatures during embryonic development, which makes them suitable subjects for testing the effects of warming on reproduction. We raised adult females and incubated their eggs under different thermal conditions that mimicked potential climate warming. Female reproduction, embryonic development and hatchling traits were monitored to evaluate the reproductive response to warming. Experimental warming induced females to lay eggs earlier, but it did not affect the developmental stage of embryos at oviposition or the reproductive output. The high temperatures experienced by gravid females during warming treatments reduced the incubation period and increased embryonic mortality. The locomotor performance of hatchlings was not affected by the maternal thermal environment, but it was affected by the warming treatment during embryonic development. Our results suggest that climate warming might have a profound effect on fitness-relevant traits both at embryonic and post-embryonic stages in oviparous lizards. PMID:23731813

Lu, Hongliang; Wang, Yong; Tang, Wenqi; DU, Weiguo

2013-06-01

24

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

25

Recent Rapid Regional Climate Warming on the Antarctic Peninsula  

NASA Astrophysics Data System (ADS)

The Intergovernmental Panel on Climate Change (IPCC) confirmed that global warming was 0.6 ñ 0.2 degrees C during the 20th Century and cited increases in greenhouse gases as a likely contributor. But this average conceals the complexity of observed climate change, which is seasonally biased, decadally variable and geographically patchy. In particular, over the last 50 years three high-latitude areas have undergone recent rapid regional (RRR) warming ? substantially more rapid than the global mean. We discuss the spatial and temporal significance of RRR warming in one area, the Antarctic Peninsula. New analyses of station records show no ubiquitous polar amplification of global warming but significant RRR warming on the Antarctic Peninsula. We investigate the likelihood that this could be amplification of a global warming, and use climate-proxy data to indicate that this RRR warming on the Antarctic Peninsula is unprecedented over the last two millennia and unlikely to be a natural mode of variability. We can show a strong connection between RRR warming and reduced sea-ice duration in an area on the west of the Antarctic Peninsula, but here we cannot yet distinguish cause and effect. Thus for the present we cannot determine which process causes the RRR warming, and until the mechanism initiating and sustaining it is understood, and is convincingly reproduced in climate models, we lack a sound basis for predicting climate change in this region over the coming century.

Vaughan, D. G.; Marshall, G. J.; Connolley, W. M.; Parkinson, C.; Mulvaney, R.; Hodgson, D. A.; King, J. C.; Pudsey, C. J.; Turner, J.

2002-12-01

26

El Niño dynamics in the warm Pliocene climate  

NASA Astrophysics Data System (ADS)

A 'permanent' El Niño climate state has been suggested for the warm Pliocene interval, the most recent period similar to what is expected for the twenty-first century. Main piece of evidence of such conditions is the small east-west sea surface temperature (SST) difference that is found in proxy temperature records of the equatorial Pacific Ocean. Using a version of the Zebiak-Cane model for which the tropical Pacific background state is part of the solution, we study the sensitivity of the Pacific background climate and El Niño/Southern Oscillation (ENSO) variability to Pliocene climate changes. The parameters varied in this sensitivity study include changes in the trade wind strength due to a reduced equator-to-pole temperature gradient, higher global mean temperatures and an open Panama gateway. All these changes lead to a westward shift of the position of the cold tongue along the equator by up to 2000 km. This result is consistent with data from the PRISM3D Pliocene SST reconstruction. The associated changes in thermocline tilt across the equatorial Pacific are, however, not uniform and depend on the relative strength of the processes involved. Our model further suggests that ENSO variability is present and similar to today in the Pliocene climate. A background climate that would resemble a 'permanent' El Niño with weak to no east-west temperature difference along the equator is only found for a very weak equator-pole temperature gradient, which seems unrealistic for the Pliocene climate.

von der Heydt, A. S.; Dijkstra, H. A.

2012-04-01

27

Impacts of a Warming Arctic - Arctic Climate Impact Assessment  

Microsoft Academic Search

The Arctic is now experiencing some of the most rapid and severe climate change on earth. Over the next 100 years, climate change is expected to accelerate, contributing to major physical, ecological, social, and economic changes, many of which have already begun. Changes in arctic climate will also affect the rest of the world through increased global warming and rising

2004-01-01

28

Global Climate Change: The Effects of Global Warming  

NSDL National Science Digital Library

In this lesson, students conduct an experiment to learn about CO2 levels found in four different gases. Through this experiment and a set of multimedia resources, they will learn how atmospheric levels of CO2 relate to climate change and global warming, explore the effects of global warming on the environment (as indicated by the changes in Earth's glacial ice), and consider human contributions to global warming, particularly from the use of automobiles.

2005-01-01

29

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

30

Climate Warming and Water Management Adaptation for California  

Microsoft Academic Search

The ability of California's water supply system to adapt to long-term climatic and demographic changes is examined. Two climate warming and a historical climate scenario are examined with population and land use estimates for the year 2100 using a statewide economic-engineering optimization model of water supply management. Methodologically, the results of this analysis indicate that for long-term climate change studies

Stacy K. Tanaka; Tingju Zhu; Jay R. Lund; Richard E. Howitt; Marion W. Jenkins; Manuel A. Pulido; Mélanie Tauber; Randall S. Ritzema; Inês C. Ferreira

2006-01-01

31

Terrestrial Carbon Cycle Feedback to Climate Warming: Experimental Evidence  

NASA Astrophysics Data System (ADS)

Global climate modeling has demonstrated that climate warming would stimulate respiratory CO2 release from the terrestrial ecosystems to the atmosphere, which in turn leads to more warming in the climate system. This positive feedback between the climate change and the terrestrial carbon cycle can form a vicious cycle that potentially leads to a dangerous threat to ecosystem functioning and service. Some of the key processes underlying this feedback loop, however, have not been carefully examined by experimental studies. Those key processes include temperature sensitivity of ecosystem carbon influx; regulation of carbon processes by warming-induced changes in species composition, and nutrient and water availability; and phenology and timing of ecosystem processes under warming. We have conducted two warming experiments in a Southern Great Plains prairie to examine ecosystem responses to climate warming. We used infrared heaters to elevate soil temperature by approximately 2.0 and 4.0 oC, respectively, during the experimental period. Our results indicate that plant biomass growth increased by approximately 20% in the warmed plots in comparison to that in the control plots. The increased plant productivity likely resulted from extended length of growing seasons since warming advanced phenology of early-flowering species and delayed phenology of late-flowering species, leading to an extension of the growing season. Leaf photosynthesis, however, was not strongly affected by warming. Warming also considerably increased C4 plant biomass and caused slight decreases in growth of C3 plants. Increased C4 biomass and litter production resulted in decreases in quality and decomposition of bulk litter at the ecosystem scale, leading to an increase in litter mass at the soil surface. Soil respiration did not significantly increase in the first two years but increased by 8-10% in the last several years, largely due to increased root respiration and litter pool sizes. We did not observe much change in soil C content under warming, indicating that increased plant biomass counterbalanced the increased carbon loss via respiration. The increased biomass production was accompanied by increases in plant nitrogen uptake and use efficiency. Decreased litter quality and increased litter pools may trigger a negative nitrogen feedback to decrease nitrogen releases from litter and availability for plants over time. Overall, our data from the Great Plains prairie do not support the notion that warming stimulation of soil respiration is the major feedback process to climate change. A realistic prediction of the future carbon cycle and climate change may require more ecosystem processes other than the respiration to be incorporated into climate models.

Luo, Y.; Zhou, X.; Sherry, R.

2006-12-01

32

Climate warming and precipitation redistribution modify tree-grass interactions and tree species establishment in a warm-temperate savanna.  

PubMed

Savanna tree-grass interactions may be particularly sensitive to climate change. Establishment of two tree canopy dominants, post oak (Quercus stellata) and eastern redcedar (Juniperus virginiana), grown with the dominant C4 perennial grass (Schizachyrium scoparium) in southern oak savanna of the United States were evaluated under four climatic scenarios for 6 years. Tree-grass interactions were examined with and without warming (+1.5 °C) in combination with a long-term mean rainfall treatment and a modified rainfall regime that redistributed 40% of summer rainfall to spring and fall, intensifying summer drought. The aim was to determine: (1) the relative growth response of these species, (2) potential shifts in the balance of tree-grass interactions, and (3) the trajectory of juniper encroachment into savannas, under these anticipated climatic conditions. Precipitation redistribution reduced relative growth rate (RGR) of trees grown with grass. Warming increased growth of J. virginiana and strongly reduced Q. stellata survival. Tiller numbers of S. scoparium plants were unaffected by warming, but the number of reproductive tillers was increasingly suppressed by intensified drought each year. Growth rates of J. virginiana and Q. stellata were suppressed by grass presence early, but in subsequent years were higher when grown with grass. Quercus stellata had overall reduced RGR, but enhanced survival when grown with grass, while survival of J. virginiana remained near 100% in all treatments. Once trees surpassed a threshold height of 1.1 m, both tiller number and survival of S. scoparium plants were drastically reduced by the presence of J. virginiana, but not Q. stellata. Juniperus virginiana was the only savanna dominant in which neither survival nor final aboveground mass were adversely affected by the climate scenario of warming and intensified summer drought. These responses indicate that climate warming and altered precipitation patterns will further accelerate juniper encroachment and woody thickening in a warm-temperate oak savanna. PMID:23504841

Volder, Astrid; Briske, David D; Tjoelker, Mark G

2012-12-13

33

Greenhouse warmed Europe: thermoregulatory criteria for future indoor climate management  

NASA Astrophysics Data System (ADS)

The implications of Greenhouse warming upon indoor climate control are examined with emphasis upon climatic adjustment in thermal comfort. Maps of Europe are shown for doubled CO2 scenarios, together with first order estimates of possible energy savings. Comment is passed upon appropriate building design.

Auliciens, Andris

1992-12-01

34

River Runoff Sensitivity in Eastern Siberia to Global Climate Warming  

Microsoft Academic Search

During several last decades significant climate warming is observed in permafrost regions of Eastern Siberia. These changes include rise of air temperature as well as precipitation. Changes in regional climate are accompanied with river runoff changes. The analysis of the data shows that in the past 25 years, the largest contribution to the annual river runoff increase in the lower

A. G. Georgiadi; I. P. Milyukova; E. Kashutina

2008-01-01

35

Climate science: Global warming at the poles  

Microsoft Academic Search

Natural climate variability and limited observational records have made identifying human-influenced climate change at the poles difficult. But a human signature is now emerging in rising Arctic and Antarctic temperatures.

Andrew Monaghan; David Bromwich

2008-01-01

36

Biomass production in experimental grasslands of different species richness during three years of climate warming  

NASA Astrophysics Data System (ADS)

Here we report on the single and combined impacts of climate warming and species richness on the biomass production in experimental grassland communities. Projections of a future warmer climate have stimulated studies on the response of terrestrial ecosystems to this global change. Experiments have likewise addressed the importance of species numbers for ecosystem functioning. There is, however, little knowledge on the interplay between warming and species richness. During three years, we grew experimental plant communities containing one, three or nine grassland species in 12 sunlit, climate-controlled chambers in Wilrijk, Belgium. Half of these chambers were exposed to ambient air temperatures (unheated), while the other half were warmed by 3°C (heated). Equal amounts of water were added to heated and unheated communities, so that warming would imply drier soils if evapotranspiration was higher. Biomass production was decreased due to warming, both aboveground (-29%) and belowground (-25%), as negative impacts of increased heat and drought stress in summer prevailed. Complementarity effects, likely mostly through both increased aboveground spatial complementarity and facilitative effects of legumes, led to higher shoot and root biomass in multi-species communities, regardless of the induced warming. Surprisingly, warming suppressed productivity the most in 9-species communities, which may be attributed to negative impacts of intense interspecific competition for resources under conditions of high abiotic stress. Our results suggest that warming and the associated soil drying could reduce primary production in many temperate grasslands, and that this will not necessarily be mitigated by efforts to maintain or increase species richness.

de Boeck, H. J.; Lemmens, C. M. H. M.; Zavalloni, C.; Gielen, B.; Malchair, S.; Carnol, M.; Merckx, R.; van den Berge, J.; Ceulemans, R.; Nijs, I.

2008-04-01

37

Biomass production in experimental grasslands of different species richness during three years of climate warming  

NASA Astrophysics Data System (ADS)

Here we report on the single and combined impacts of climate warming and species richness on the biomass production in experimental grassland communities. Projections of a future warmer climate have stimulated studies on the response of terrestrial ecosystems to this global change. Experiments have likewise addressed the importance of species numbers for ecosystem functioning. There is, however, little knowledge on the interplay between warming and species richness. During three years, we grew experimental plant communities containing one, three or nine grassland species in 12 sunlit, climate-controlled chambers in Wilrijk, Belgium. Half of these chambers were exposed to ambient air temperatures (unheated), while the other half were warmed by 3°C (heated). Equal amounts of water were added to heated and unheated communities, so that warming would imply drier soils if evapotranspiration was higher. Biomass production was decreased due to warming, both aboveground (-29%) and belowground (-25%), as negative impacts of increased heat and drought stress in summer prevailed. Increased resource partitioning, likely mostly through spatial complementarity, led to higher shoot and root biomass in multi-species communities, regardless of the induced warming. Surprisingly, warming suppressed productivity the most in 9-species communities, which may be attributed to negative impacts of intense interspecific competition for resources under conditions of high abiotic stress. Our results suggest that warming and the associated soil drying could reduce primary production in many temperate grasslands, and that this will not necessarily be mitigated by efforts to maintain or increase species richness.

de Boeck, H. J.; Lemmens, C. M. H. M.; Gielen, B.; Malchair, S.; Carnol, M.; Merckx, R.; van den Berge, J.; Ceulemans, R.; Nijs, I.

2007-12-01

38

Climate change: Brief but warm Antarctic summer  

NASA Astrophysics Data System (ADS)

A temperature record derived from measurements of an ice core drilled on James Ross Island, Antarctica, prompts a rethink of what has triggered the recent warming trends on the Antarctic Peninsula. See Letter p.141

Steig, Eric J.

2012-09-01

39

Climatic bisection of the last interglacial warm period in the Polar North Atlantic  

NASA Astrophysics Data System (ADS)

New multiproxy marine data of the Eemian interglacial (MIS5e) from the Norwegian Sea manifest a cold event with near-glacial surface ocean summer temperatures (3-4 °C). This mid-Eemian cooling divided the otherwise relatively warm interglacial climate and was associated with widespread expansions of winter sea-ice and polar water masses due to changes in atmospheric circulation and ocean stability. While the data also verify a late rather than early last interglacial warm peak, which is in general disharmony with northern hemisphere insolation maximum and the regional climatic progression of the early Holocene, the cold event itself was likely instrumental for delaying the last interglacial climate development in the Polar North when compared with regions farther south. Such a 'climatic decoupling' of the Polar region may bear profound implications for the employment of Eemian conditions to help evaluate the present and future state of the Arctic cryosphere during a warming interglacial.

Bauch, Henning A.; Kandiano, Evguenia S.; Helmke, Jan; Andersen, Nils; Rosell-Mele, Antoni; Erlenkeuser, Helmut

2011-07-01

40

Impacts of a Warming Arctic - Arctic Climate Impact Assessment  

NASA Astrophysics Data System (ADS)

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

Arctic Climate Impact Assessment

2004-12-01

41

Global Warming and Climate Change Science  

NASA Astrophysics Data System (ADS)

Global climate change has emerged as a major scientific and political issue within a few short decades. Scientific evidence clearly indicates that this change is a result of a complex interplay between a number of human-related and natural earth systems. While the complexity of the earth-ocean-atmosphere system makes the understanding and prediction of global climate change very difficult, improved scientific knowledge and research capabilities are advancing our understanding of global climate change resulting from rising atmospheric levels of radiatively important (mostly heat-trapping) gases and particles. The effects of climate change can be assessed with climate models, which account for complex physical, chemical and biological processes, and interactions of these processes with human activities, especially the burning of fossil fuels along with land use changes. This presentation begins with a discussion of the current understanding of the concerns about climate change, and then discusses the role climate models in scientific projections of climate change as well as their current strengths and weaknesses.

Jain, Atul

2008-03-01

42

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....

43

Global Warming - The Science of Climate Change  

Microsoft Academic Search

Extremely topical over recent years, global warming has been the subject of a huge and growing amount of literature. Current literature however tends to fall into two camps: that which is highly scientific in nature and inaccessible to the average student, and that which is directed to the \\

Frances Drake

2000-01-01

44

Climatic Warming of Atlantic Intermediate Waters  

Microsoft Academic Search

Interdecadal temperature variability of the Atlantic Ocean is investigated by differencing hydrographic sections taken from the 1920s through the 1990s. A comprehensive reanalysis of North Atlantic sections and the inclusion of South Atlantic sections show that warming seen previously in the North Atlantic extends to the South Atlantic. The largest statistically significant changes occur on pressure surfaces between 1000 and

Brian K. Arbic; W. Brechner Owens

2001-01-01

45

Global Warming and Climate Change Science  

Microsoft Academic Search

Global climate change has emerged as a major scientific and political issue within a few short decades. Scientific evidence clearly indicates that this change is a result of a complex interplay between a number of human-related and natural earth systems. While the complexity of the earth-ocean-atmosphere system makes the understanding and prediction of global climate change very difficult, improved scientific

Atul Jain

2008-01-01

46

Climate and conflicts: the security risks of global warming  

Microsoft Academic Search

Since the publication of the fourth assessment report of the Intergovernmental Panel on Climate Change in 2007, the securitization\\u000a of global warming has reached a new level. Numerous public statements and a growing research literature have discussed the\\u000a potential security risks and conflicts associated with climate change. This article provides an overview of this debate and\\u000a introduces an assessment framework

Jürgen Scheffran; Antonella Battaglini

2011-01-01

47

Recent Rapid Regional Climate Warming on the Antarctic Peninsula  

Microsoft Academic Search

The Intergovernmental Panel on Climate Change (IPCC) confirmed that mean global warming was 0.6 ± 0.2 °C during the 20th century and cited anthropogenic increases in greenhouse gases as the likely cause of temperature rise in the last 50 years. But this mean value conceals the substantial complexity of observed climate change, which is seasonally- and diurnally-biased, decadally-variable and geographically

David G. Vaughan; Gareth J. Marshall; William M. Connolley; Claire Parkinson; Robert Mulvaney; Dominic A. Hodgson; John C. King; Carol J. Pudsey; John Turner

2003-01-01

48

Hudson Bay Ringed Seal: Ecology in a Warming Climate  

Microsoft Academic Search

\\u000a Ringed seals (Phoca hispida) have evolved to exploit snow covered sea-ice platforms for reproduction and survival and may face critical challenges with\\u000a ongoing and predicted climate change. The Hudson Bay ecosystem is already showing signs of climate warming raising concerns\\u000a for the ecological, economical, and culturally-significant ringed seals of Hudson Bay. This chapter summarizes the current\\u000a knowledge on ringed seals

M. Chambellant

49

Impacts of climate warming on terrestrial ectotherms across latitude.  

PubMed

The impact of anthropogenic climate change on terrestrial organisms is often predicted to increase with latitude, in parallel with the rate of warming. Yet the biological impact of rising temperatures also depends on the physiological sensitivity of organisms to temperature change. We integrate empirical fitness curves describing the thermal tolerance of terrestrial insects from around the world with the projected geographic distribution of climate change for the next century to estimate the direct impact of warming on insect fitness across latitude. The results show that warming in the tropics, although relatively small in magnitude, is likely to have the most deleterious consequences because tropical insects are relatively sensitive to temperature change and are currently living very close to their optimal temperature. In contrast, species at higher latitudes have broader thermal tolerance and are living in climates that are currently cooler than their physiological optima, so that warming may even enhance their fitness. Available thermal tolerance data for several vertebrate taxa exhibit similar patterns, suggesting that these results are general for terrestrial ectotherms. Our analyses imply that, in the absence of ameliorating factors such as migration and adaptation, the greatest extinction risks from global warming may be in the tropics, where biological diversity is also greatest. PMID:18458348

Deutsch, Curtis A; Tewksbury, Joshua J; Huey, Raymond B; Sheldon, Kimberly S; Ghalambor, Cameron K; Haak, David C; Martin, Paul R

2008-05-05

50

Non-climatic thermal adaptation: implications for species' responses to climate warming  

PubMed Central

There is considerable interest in understanding how ectothermic animals may physiologically and behaviourally buffer the effects of climate warming. Much less consideration is being given to how organisms might adapt to non-climatic heat sources in ways that could confound predictions for responses of species and communities to climate warming. Although adaptation to non-climatic heat sources (solar and geothermal) seems likely in some marine species, climate warming predictions for marine ectotherms are largely based on adaptation to climatically relevant heat sources (air or surface sea water temperature). Here, we show that non-climatic solar heating underlies thermal resistance adaptation in a rocky–eulittoral-fringe snail. Comparisons of the maximum temperatures of the air, the snail's body and the rock substratum with solar irradiance and physiological performance show that the highest body temperature is primarily controlled by solar heating and re-radiation, and that the snail's upper lethal temperature exceeds the highest climatically relevant regional air temperature by approximately 22°C. Non-climatic thermal adaptation probably features widely among marine and terrestrial ectotherms and because it could enable species to tolerate climatic rises in air temperature, it deserves more consideration in general and for inclusion into climate warming models.

Marshall, David J.; McQuaid, Christopher D.; Williams, Gray A.

2010-01-01

51

Effects of climate warming on fish thermal habitat in streams of the United States  

Microsoft Academic Search

The effects of climate warming on the thermal habitat of 57 species of fish of the U.S. were estimated using results for a doubling of atmospheric carbon dioxide that were predicted by the Canadian Climate Center general circulation model. Baseline water temperature conditions were calculated from data collected at 1,700 U.S. Geological Survey stream monitoring stations across the U.S. Water

John G. Eaton; Robert M. Scheller

1996-01-01

52

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

53

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.

Nutshell, Planet; Network, Utah E.

54

Geoengineering the Climate: Approaches to Counterbalancing Global Warming  

Microsoft Academic Search

For the past two hundred years, the inadvertent release of carbon dioxide and other radiatively active gases and aerosols, particularly as a result of combustion of fossil fuels and changes in land cover, have been contributing to global climate change. Global warming to date is approaching 1°C, and this is being accompanied by reduced sea ice, rising sea level, shifting

M. C. MacCracken

2005-01-01

55

Case for a Wet, Warm Climate on Early Mars.  

National Technical Information Service (NTIS)

Arguments are presented in support of the idea that Mars possessed a dense CO2 atmosphere and a wet, warm climate early in its history. The plausibility of a CO2 greenhouse is tested by formulating a simple model of the CO2 geochemical cycle on early Mars...

J. B. Pollack J. F. Kasting S. M. Richardson K. Poliakoff

1987-01-01

56

Effect of climatic warming on the west Antarctic ice sheet  

Microsoft Academic Search

Climatic warming could cause increased melting from Antarctic ice shelves. Continued weakening of the ice shelves in this way would result in the ultimate collapse of most of the West Antarctic ice sheet. For complete removal of the ice shelves collapse of the ice sheet and a 5 m rise in world sea level could occur in < 100 yr.

Robert H. Thomas; Timothy J. O. Sanderson; Keith E. Rose

1979-01-01

57

Seventh grade students' conceptions of global warming and climate change  

Microsoft Academic Search

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 administered to students. These data were

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

2009-01-01

58

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

59

Predicting climate change. An improved model of warming commitment  

Microsoft Academic Search

The Model of Warming Commitment, an integration of several simulation models relating to the global greenhouse problem, provided a new way of projecting climate changes. The new model projects energy demand by using a disaggregated, end-use analysis, rather than one primarily based on assumed rates of population and GNP growth. The carbon cycle model is more complete, and the expanded

Mintzer

1988-01-01

60

Climate Warming and Disease Risks for Terrestrial and Marine Biota  

NASA Astrophysics Data System (ADS)

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

2002-06-01

61

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

62

Modelling effects of habitat fragmentation on the ability of trees to respond to climatic warming  

Microsoft Academic Search

The ability of trees to migrate in response to climatic warming was simulated under various conditions of habitat availability. The model uses Holocene tree migration rates to approximate maximum migration rates in a forested landscape. Habitat availability and local population size was varied systematically under two dispersal and colonization models. These dispersal models varied in the likelihood of long-distance dispersal

Mark W. Schwartz

1993-01-01

63

A farm-level analysis of economic and agronomic impacts of gradual climate warming  

Microsoft Academic Search

The potential economic and agronomic impacts of gradual climate warming are examined at the farm level. Three models of the relevant climatic, agronomic, and economic processes are developed and linked to address climate change impacts and agricultural adaptability. Several climate warming severity. The results indicate that grain farmers in southern Minnesota can effectively adapt to a gradually changing climate (warmer

Harry M. Kaiser; R. Sampath; S. J. Riha; D. S. Wilks; D. G. Rossiter

1993-01-01

64

Ancient tropical climates warm San Francisco gathering  

Microsoft Academic Search

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

R. Kerr

1994-01-01

65

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

66

Warming Up the Classroom Climate for Women.  

ERIC Educational Resources Information Center

Presents five exercises, based on the "Chilly Climate" papers, designed to enhance faculty and staff sensitivity to the need of providing a comfortable learning environment for women. Covers definition of sexism, pronouns as power, gender differences in experiences with sexism, incorporating feminist scholarship into traditional courses,…

Rosser, Sue V.

1989-01-01

67

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

68

Ocean climate and seal condition  

Microsoft Academic Search

BACKGROUND: The condition of many marine mammals varies with fluctuations in productivity and food supply in the ocean basin where they forage. Prey is impacted by physical environmental variables such as cyclic warming trends. The weaning weight of northern elephant seal pups, Mirounga angustirostris, being closely linked to maternal condition, indirectly reflects prey availability and foraging success of pregnant females

Burney J Le Boeuf; Daniel E Crocker

2005-01-01

69

Method of warming cold engines in cold climates  

SciTech Connect

This patent describes a method of warming cold engines in low temperature conditions comprising the steps of: (a) placing a flammable compound inside a nonflammable fabric bag; (b) placing the bag on an engine; and (c) igniting the flammable compound.

Forschirm, A.

1988-12-06

70

Birds are tracking climate warming, but not fast enough  

PubMed Central

Range shifts of many species are now documented as a response to global warming. But whether these observed changes are occurring fast enough remains uncertain and hardly quantifiable. Here, we developed a simple framework to measure change in community composition in response to climate warming. This framework is based on a community temperature index (CTI) that directly reflects, for a given species assemblage, the balance between low- and high-temperature dwelling species. Using data from the French breeding bird survey, we first found a strong increase in CTI over the last two decades revealing that birds are rapidly tracking climate warming. This increase corresponds to a 91?km northward shift in bird community composition, which is much higher than previous estimates based on changes in species range edges. During the same period, temperature increase corresponds to a 273?km northward shift in temperature. Change in community composition was thus insufficient to keep up with temperature increase: birds are lagging approximately 182?km behind climate warming. Our method is applicable to any taxa with large-scale survey data, using either abundance or occurrence data. This approach can be further used to test whether different delays are found across groups or in different land-use contexts.

Devictor, Vincent; Julliard, Romain; Couvet, Denis; Jiguet, Frederic

2008-01-01

71

First tropical warm rain estimates could improve global climate models  

NSDL National Science Digital Library

This study breaks down the type of rainfall in the tropical zones. Microwave images and radar data from the Tropical Rainfall Measuring Mission were examined. It was found that approximately 72 percent of the total rain area and 31 percent of the total rain amount in the tropics comes from warm rain. The relationship between liquid water in a cloud and the rain rate was also measured. Results can be used in climate models to represent convection cycles and their role in global warming.

Lau, William; Wu, H. T.; Agu

72

Cold Climate, Warm Climates: How Can We Tell Past Temperatures?  

NSDL National Science Digital Library

This brief NASA article provides general information about paleoclimatology (the study of past climate). Focusing on ice core data and foraminifera (shelled marine microorganisms) in deep sea sediments, the article provides a summary of how paleoclimate can be inferred.

Schmidt, Gavin; Studies, Nasa G.

73

Insects overshoot the expected upslope shift caused by climate warming.  

PubMed

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

2013-06-07

74

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

75

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

76

BVOCs: plant defense against climate warming?  

Microsoft Academic Search

Plants emit a substantial amount of biogenic volatile organic compounds (BVOCs) into the atmosphere. These BVOCs represent a large carbon loss and can be up to ?10% of that fixed by photosynthesis under stressful conditions and up to 100gCm?2 per year in some tropical ecosystems. Among a variety of proven and unproven BVOC functions in plants and roles in atmospheric

Josep Peñuelas; Joan Llusià

2003-01-01

77

Warming experiments underpredict plant phenological responses to climate change  

NASA Astrophysics Data System (ADS)

Warming experiments are relied on increasingly to estimate plant responses to global 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 timing of flowering and leafout. We compared observational phenology studies with warming experiments spanning four continents and 1,634 species. Using a common measure of temperature sensitivity (change in days per degree C), we show that experiments underpredict advances in timing of flowering and leafing by 8.5X and 4.0X, respectively, compared to long-term observations. For species common to both study types, experimental results did not match observational data in sign or magnitude. The observational data also show highest sensitivity for species that flower earliest in the spring, but this trend was not reflected in the experiments. These significant mismatches appear unrelated to 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 observational data or from remediable artifacts in the experiments that reduce irradiance, dry soils, and thus dampen phenological responses to manipulated warming. Our results introduce uncertainty in ecosystem models informed solely by experiments, and suggest predicted responses to climate change from such models should be re-evaluated.

Wolkovich, E.; Cook, B.; Forecasting Phenology Working Group

2012-04-01

78

Atlantic Warm Pool Trigger for the Younger Dryas Climate Event  

NASA Astrophysics Data System (ADS)

There is growing evidence that variability in the size and heat content of the tropical Atlantic Warm Pool impacts circum-North Atlantic climate via the Atlantic Multi-decadal Oscillation mode (Wang et al., 2008). The Atlantic Warm Pool spans the Gulf of Mexico, Caribbean Sea and the western tropical North Atlantic. Barbados is located near the center of the tropical Atlantic Warm Pool and coupled ocean models suggest that Barbados remains near the center of the tropical Atlantic Warm Pool under varying wind stress simulations. Measurements of the oxygen isotope paleothermometer in Acropora palmata coral species recovered from cores offshore Barbados, show a 3oC monotonic decrease in sea surface temperature from 13106 ± 83 to 12744 ± 61 years before present (errors given as 2 sigma). This interval corresponds to a sea level rise from 71.4 meters to 67.1 meters below present levels at Barbados. The 3oC temperature decrease is captured in eight A. palmata specimens that are in stratigraphic sequence, 230Th/234U dated, and analyzed for oxygen isotopes. All measurements are replicated. We are confident that this is the warm pool equivalent of the Younger Dryas climate event. The initiation of this temperature drop in the Atlantic Warm Pool predates the Younger Dryas start in Greenland ice cores, reported to start at 12896 ± 138 years (relative to AD 2000) (Rasmussen et al., 2006), while few other Younger Dryas climate records are dated with similar accuracy to make the comparison. Rasmussen, S.O., Andersen, K.K., Svensson, A.M., Steffensen, J.P., Vinther, B.M., Clausen, H.B., Siggaard-Andersen, M.L., Johnsen, S.J., Larsen, L.B., Dahl-Jensen, D., Bigler, M., Röthlisberger, R., Fischer, H., Goto-Azuma, K., Hansson, M.E., and Ruth, U., 2006, A new Greenland ice core chronology for the last glacial termination: J. Geophys. Res., v. 111, p. D06102. Wang, C., Lee, S.-K., and Enfield, D.B., 2008, Atlantic Warm Pool acting as a link between Atlantic Multidecadal Oscillation and Atlantic tropical cyclone activity: Geochem. Geophys. Geosyst., v. 9, p. Q05V03.

Abdul, N. A.; Mortlock, R. A.; Wright, J. D.; Fairbanks, R. G.; Teneva, L. T.

2011-12-01

79

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

2011-08-18

80

Predicted effects of climate warming on the distribution of 50 stream fishes in Wisconsin, U.S.A.  

USGS Publications Warehouse

Summer air and stream water temperatures are expected to rise in the state of Wisconsin, U.S.A., over the next 50 years. To assess potential climate warming effects on stream fishes, predictive models were developed for 50 common fish species using classification-tree analysis of 69 environmental variables in a geographic information system. Model accuracy was 56.0-93.5% in validation tests. Models were applied to all 86 898 km of stream in the state under four different climate scenarios: current conditions, limited climate warming (summer air temperatures increase 1?? C and water 0.8?? C), moderate warming (air 3?? C and water 2.4?? C) and major warming (air 5?? C and water 4?? C). With climate warming, 23 fishes were predicted to decline in distribution (three to extirpation under the major warming scenario), 23 to increase and four to have no change. Overall, declining species lost substantially more stream length than increasing species gained. All three cold-water and 16 cool-water fishes and four of 31 warm-water fishes were predicted to decline, four warm-water fishes to remain the same and 23 warm-water fishes to increase in distribution. Species changes were predicted to be most dramatic in small streams in northern Wisconsin that currently have cold to cool summer water temperatures and are dominated by cold-water and cool-water fishes, and least in larger and warmer streams and rivers in southern Wisconsin that are currently dominated by warm-water fishes. Results of this study suggest that even small increases in summer air and water temperatures owing to climate warming will have major effects on the distribution of stream fishes in Wisconsin. ?? 2010 The Authors. Journal of Fish Biology ?? 2010 The Fisheries Society of the British Isles.

Lyons, J.; Stewart, J. S.; Mitro, M.

2010-01-01

81

Foraging by forest ants under experimental climatic warming: a test at two sites  

PubMed Central

Climatic warming is altering the behavior of individuals and the composition of communities. However, recent studies have shown that the impact of warming on ectotherms varies geographically: species at warmer sites where environmental temperatures are closer to their upper critical thermal limits are more likely to be negatively impacted by warming than are species inhabiting relatively cooler sites. We used a large-scale experimental temperature manipulation to warm intact forest ant assemblages in the field and examine the impacts of chronic warming on foraging at a southern (North Carolina) and northern (Massachusetts) site in eastern North America. We examined the influence of temperature on the abundance and recruitment of foragers as well as the number of different species observed foraging. Finally, we examined the relationship between the mean temperature at which a species was found foraging and the critical thermal maximum temperature of that species, relating functional traits to behavior. We found that forager abundance and richness were related to the experimental increase in temperature at the southern site, but not the northern site. Additionally, individual species responded differently to temperature: some species foraged more under warmer conditions, whereas others foraged less. Importantly, these species-specific responses were related to functional traits of species (at least at the Duke Forest site). Species with higher critical thermal maxima had greater forager densities at higher temperatures than did species with lower critical thermal maxima. Our results indicate that while climatic warming may alter patterns of foraging activity in predictable ways, these shifts vary among species and between sites. More southerly sites and species with lower critical thermal maxima are likely to be at greater risk to ongoing climatic warming.

Stuble, Katharine L; Pelini, Shannon L; Diamond, Sarah E; Fowler, David A; Dunn, Robert R; Sanders, Nathan J

2013-01-01

82

Recent Antarctic Peninsula warming relative to Holocene climate and ice-shelf history.  

PubMed

Rapid warming over the past 50?years on the Antarctic Peninsula is associated with the collapse of a number of ice shelves and accelerating glacier mass loss. In contrast, warming has been comparatively modest over West Antarctica and significant changes have not been observed over most of East Antarctica, suggesting that the ice-core palaeoclimate records available from these areas may not be representative of the climate history of the Antarctic Peninsula. Here we show that the Antarctic Peninsula experienced an early-Holocene warm period followed by stable temperatures, from about 9,200 to 2,500?years ago, that were similar to modern-day levels. Our temperature estimates are based on an ice-core record of deuterium variations from James Ross Island, off the northeastern tip of the Antarctic Peninsula. 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. This cooling was part of a millennial-scale climate excursion with opposing anomalies on the eastern and western sides of the Antarctic Peninsula. Although warming of the northeastern Antarctic Peninsula began around 600 years ago, the high rate of warming over the past century is unusual (but not unprecedented) in the context of natural climate variability over the past two millennia. The connection shown here between past temperature and ice-shelf stability suggests that warming for several centuries rendered ice shelves on the northeastern Antarctic Peninsula vulnerable to collapse. Continued warming to temperatures that now exceed the stable conditions of most of the Holocene epoch is likely to cause ice-shelf instability to encroach farther southward along the Antarctic Peninsula. PMID:22914090

Mulvaney, Robert; Abram, Nerilie J; Hindmarsh, Richard C A; Arrowsmith, Carol; Fleet, Louise; Triest, Jack; Sime, Louise C; Alemany, Olivier; Foord, Susan

2012-09-01

83

The hydroclimatological response to global warming based on the dynamically downscaled climate change scenario  

NASA Astrophysics Data System (ADS)

Given the discernable evidences of climate changes due to human activity, there is a growing demand for the reliable climate change scenario in response to future emission forcing. One of the most significant impacts of climate changes can be that on the hydrological process. Changes in the seasonality and increase in the low and high rainfall extremes can severely influence the water balance of river basin, with serious consequences for societies and ecosystems. In fact, recent studies have reported that East Asia including the Korean peninsula is regarded to be a highly vulnerability region under global warming, in particular for water resources. As an attempt accurately assess the impact of climate change over Korea, we performed a downscaling of the ECAHM5-MPI/OM global projection under the A1B emission scenario for the period 1971-2100 using the RegCM3 one-way double-nested system. Physically based long-term (130 years) fine-scale (20 km) climate information is appropriate for analyzing the detailed structure of the hydroclimatological response to climate change. Changes in temperature and precipitation are translated to the hydrological condition in a direct or indirect way. The change in precipitation shows a distinct seasonal variations and a complicated spatial pattern. While changes in total precipitation do not show any relevant trend, the change patterns in daily precipitation clearly show an enhancement of high intensity precipitation and a reduction of weak intensity precipitation. The increase of temperature enhances the evapotranspiration, and hence the actual water stress becomes more pronounced in the future climate. Precipitation, snow, and runoff changes show the relevant topographical modulation under global warming. This study clearly demonstrates the importance of a refined topography for improving the accuracy of the local climatology. Improved accuracy of regional climate projection could lead to an enhanced reliability of the interpretation of the warming effect, especially when viewed in the linkage climate change information and impact assessment studies.

Im, Eun-Soon; Coppola, Erika; Giorgi, Felippo

2010-05-01

84

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

85

Regional climate change under high-end global warming  

NASA Astrophysics Data System (ADS)

Global emissions of greenhouse gases have continued to rise throughout the 20th and 21st centuries. If no steps are taken to reduce these emissions, it is likely that global temperatures will exceed the limit of 2 deg.C by 2100 (relative to the preindustrial period) desired by the EU. The climate projections from the IPCC Fourth Assessment Report (AR4) suggest that global temperatures will increase between 1.6 and 6.9 deg.C by 2100, relative to the preindustrial period. Global mean temperature increases of 4 deg.C or more (referred to as 'high-end' projections) are therefore entirely possible. Here, we examine changes in temperature and precipitation from several ensembles of climate models, focusing on those projections where global mean temperatures increase by 4 deg.C or more by the 2090s. We have examined projections from the AR4 models, and the Hadley Centre's perturbed physics ensembles (Qump; based on the HadCM3 climate model). One of the Qump ensembles included an interactive carbon cycle. Previous work has shown that feedbacks between climate and the carbon cycle can result in enhanced global warming. These ensembles used greenhouse gas concentrations from a subset of the SRES emission scenarios B1, A1B, A2 and A1FI. The results show that high-end climate change would be avoided if emissions follow the B1 trajectory. However, high-end changes become increasingly frequent under the A1B, A2 and A1FI scenarios (in that order). Overall, 52 of the 131 projections analysed were classed as high-end. The high-end projections suggest that 4 deg.C global warming could be reached by the 2080s, or by the 2070s if emissions are high. If feedbacks from the carbon cycle are strong, 4 deg.C could be reached as early as the 2060s, although our current understanding suggests that such strong feedbacks are unlikely. We also compared global maps of temperature and precipitation changes from the high-end and the remaining members of each ensemble. We found that, using multi-model means, high-end projections generally have similar patterns of change to non high-end projections. This result indicates that high-end models do not behave very differently to non high-end models. Enhanced warming, of up to 15.2 C, is projected over the Arctic in the high-end projections. The projected warming in northern hemisphere winter is much greater than that seen in the summer period. Other areas which are projected to experience a large degree of warming are west and southern Africa, where temperatures may increase between 6 and 10 deg.C. Temperatures in parts of South America could increase between 6 and 13 deg.C; in the Qump ensembles, the warming is concentrated over Amazonia, but in the AR4 ensembles the warming lies to the north and south of this region. The AR4 ensembles project an area of cool water to form in the North Atlantic, between the UK, Greenland and Newfoundland; this feature is not seen in the Qump ensembles. Significant reductions in precipitation are projected by all models in the tropical and subtropical regions between 45 N and 45 S. Areas common to all ensembles are the Mediterranean, west and South Africa, and central America. However, the Qump ensembles suggest a drying in Indonesia whereas the AR4 ensembles project increasing precipitation in this area. There is also little agreement in the location of wetter and drier areas over South America between the AR4 and Qump ensembles. Some of the enhanced warming over Africa is likely to be caused by drier soils resulting from the reduced precipitation.

Sanderson, Michael; Hemming, Deborah; Betts, Richard

2010-05-01

86

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

87

Can Regional Climate Models Improve Warm Season Forecasts in the North American Monsoon Region?  

NASA Astrophysics Data System (ADS)

The goal of this work is to improve warm season forecasts in the North American Monsoon Region. To do this, we are dynamically downscaling warm season CFS (Climate Forecast System) reforecasts from 1982-2005 for the contiguous U.S. using the Weather Research and Forecasting (WRF) regional climate model. CFS is the global coupled ocean-atmosphere model used by the Climate Prediction Center (CPC), a branch of the National Center for Environmental Prediction (NCEP), to provide official U.S. seasonal climate forecasts. Recently, NCEP has produced a comprehensive long-term retrospective ensemble CFS reforecasts for the years 1980-2005. These reforecasts show that CFS model 1) has an ability to forecast tropical Pacific SSTs and large-scale teleconnection patterns, at least as evaluated for the winter season; 2) has greater skill in forecasting winter than summer climate; and 3) demonstrates an increase in skill when a greater number of ensembles members are used. The decrease in CFS skill during the warm season is due to the fact that the physical mechanisms of rainfall at this time are more related to mesoscale processes, such as the diurnal cycle of convection, low-level moisture transport, propagation and organization of convection, and surface moisture recycling. In general, these are poorly represented in global atmospheric models. Preliminary simulations for years with extreme summer climate conditions in the western and central U.S. (specifically 1988 and 1993) show that CFS-WRF simulations can provide a more realistic representation of convective rainfall processes. Thus a RCM can potentially add significant value in climate forecasting of the warm season provided the downscaling methodology incorporates the following: 1) spectral nudging to preserve the variability in the large scale circulation while still permitting the development of smaller-scale variability in the RCM; and 2) use of realistic soil moisture initial condition, in this case provided by the North American Regional Reanalysis. With these conditions, downscaled CFS-WRF reforecast simulations can produce realistic continental-scale patterns of warm season precipitation. This includes a reasonable representation of the North American monsoon in the southwest U.S. and northwest Mexico, which is notoriously difficult to represent in a global atmospheric model. We anticipate that this research will help lead the way toward substantially improved real time operational forecasts of North American summer climate with a RCM.

Dominguez, F.; Castro, C. L.

2009-12-01

88

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

89

Ecosystem responses to manipulated climate warming in a subalpine meadow  

SciTech Connect

In a subalpine meadow at the Rocky Mountain Biological Laboratory, Gunnison County, CO USA, overhead radiators were used to simulate over 4 years the ecosystem warming expected from a doubling of atmospheric carbon dioxide. Warming advanced snowmelt by a week or more, elevated midsummer soil temperatures by up to 6 degrees at midday, and reduced soil moisture by up to 25%. Soil microclimate response to heating varied considerably and explicably with season, time of day, and vegetation cover. Observed effects of heating on soil mesofaunal biomass and diversity, forb, graminoid, and shrub above-ground biomass, and net seasonal carbon balance are summarized and contrasted with their interannual variation and spatial variation along natural microclimate gradients. It is concluded that natural microclimate variations provide a poor surrogate for studying ecological effects of climate alteration.

Harte, J.; Saleska, S.; Shaw, R. [Univ. of California, Berkeley, CA (United States)

1995-09-01

90

Ecosystem responses to manipulated climate warming in a subalpine meadow  

SciTech Connect

In a subalpine meadow at the Rocky Mountain Biological Laboratory, Gunnison County, CO USA, overhead radiators were used to simulate over 4 years the ecosystem warming expected from a doubling of atmospheric carbon dioxide. Warming advanced snowmelt by a week or more, elevated midsummer soil temperatures by up to 6 degrees at midday, and reduced soil moisture by up to 25%. Soil microclimate response to heating varied considerably and explicably with season, time of day, and vegetation cover. Observed effects of heating on soil mesofaunal biomass and diversity, forb, graminoid, and shrub above-ground biomass, and net seasonal carbon balance are summarized and contrasted with their interannual variation and spatial variation along natural microclimate gradients. It is concluded that natural microclimate variations provide a poor surrogate for studying ecological effects of climate alteration.

Harte, J.; Saleska, S.; Shaw, R. [Univ. of California, Berkeley, CA (United States)] [and others

1995-06-01

91

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

92

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

93

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.

2013-09-01

94

The response of stomatal conductance to changing humidity and CO2 in a warming climate  

NASA Astrophysics Data System (ADS)

The physiological function of stomata regulates the exchange of water and carbon fluxes between vegetated and atmospheres. Atmospheric humidity and CO2 are key environmental variables in controlling the stomatal conductance (g), and both of them are projected to increase under future warming climate. Recently, several climate model experiments have investigated the impacts of climate changes on terrestrial ecosystem water vapor and CO2 fluxes through stomatal regulation. Among the land surface parameterizations in these climate models, the Ball-type's g model is most widely used to describe the characteristics of humidity- and CO2-induced stomatal closure. Although the g in Ball's model was not directly controlled by photosynthetic rate (A), it adopted a linear relationship between g and A according to a phenomenological argument. The Ball's model can predict g realistically over the controlled ambient conditions; however, it is not clear whether this linear relation can be applied to changing climate since they were not derived by causal relationship. On the other hand, a recently reported experiment by Bunce [1998, Plant Cell Environ. 21, pp. 115-120] revealed that the sensitivity of g to humidity (i.e., water vapour deficit) is not constant but a function of the ambient CO2 concentration. In this study, we show that the performance of the Ball-type models under a warming climate is not consistent with the experimental finding by Bunce [1998]. Here, we proposed a revised model and demonstrate its application in a land surface parameterization scheme.

Cho, J.; Oki, T.; Yeh, P. J.-F.; Kanae, S.; Kim, W.

2009-04-01

95

Modelling the climatic diversity of the warm interglacials  

NASA Astrophysics Data System (ADS)

The climate response to peak interglacial forcing during Marine Isotopic Stages (MIS) 1, 5, 9, 11 and 19 is examined using the Community Climate System Model 3. We determine which interglacial provides the closest analogue to peak MIS1 climate as well as how the variations in forcing between these interglacials translate into different surface climate responses.Simulated surface temperature, precipitation and sea-ice cover confirm that MIS5 and 9 are ineffective analogues of peak MIS1 climate given their relatively large astronomical and greenhouse forcing. Conversely, MIS11 and 19 are in much closer agreement with MIS1, although MIS11 exhibits the closest resemblance particularly during boreal summer. This is attributed to a greater similarity in the latitudinal distribution of insolation over the middle latitude northern hemisphere continents. This region is the most sensitive to insolation change given the absence of ice-sheet dynamics in our model.First-order surface temperature differences between the interglacials are explained by the sensitivity of the direct radiative responses to astronomical and greenhouse forcing. These include higher temperature sensitivity over land versus ocean, at high versus low latitudes and during June-July-August versus December-January-February. Sensitivity of indirect dynamical responses to insolation and greenhouse forcing also contribute to surface temperature differences between the interglacials. These include negative sea-level pressure anomalies in the North Pacific and Southern Oceans, which invigorate the meridional exchange of subpolar and subtropical air. Additionally, intense cooling and sea-ice expansion in the Nordic Seas, observed only in MIS1, 5 and 19, results in the largest variability exhibited between the interglacials. The manifestation of this cooling only after 800 years of simulation emphasises the importance of long model integrations. The examination of these features provides a framework for understanding the primary climatic differences between the warm interglacials and emphasises regions where proxies may provide effective validation of climate models.

Herold, N.; Yin, Q. Z.; Karami, M. P.; Berger, A.

2012-11-01

96

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

Microsoft Academic Search

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

James C. Chatters; Virginia L. Butler; Michael J. Scott; David M. Anderson; Duane A. Neitzel

1992-01-01

97

Implications of global warming for the climate of African rainforests.  

PubMed

African rainforests are likely to be vulnerable to changes in temperature and precipitation, yet there has been relatively little research to suggest how the regional climate might respond to global warming. This study presents projections of temperature and precipitation indices of relevance to African rainforests, using global climate model experiments to identify local change as a function of global temperature increase. A multi-model ensemble and two perturbed physics ensembles are used, one with over 100 members. In the east of the Congo Basin, most models (92%) show a wet signal, whereas in west equatorial Africa, the majority (73%) project an increase in dry season water deficits. This drying is amplified as global temperature increases, and in over half of coupled models by greater than 3% per °C of global warming. Analysis of atmospheric dynamics in a subset of models suggests that this could be partly because of a rearrangement of zonal circulation, with enhanced convection in the Indian Ocean and anomalous subsidence over west equatorial Africa, the Atlantic Ocean and, in some seasons, the Amazon Basin. Further research to assess the plausibility of this and other mechanisms is important, given the potential implications of drying in these rainforest regions. PMID:23878329

James, Rachel; Washington, Richard; Rowell, David P

2013-07-22

98

Estimating the Potential for Adaptation of Corals to Climate Warming  

PubMed Central

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 estimated the proportion of the variance in thermal tolerance traits that has a genetic basis (i.e. heritability) as a proxy for their adaptive potential in the widespread Indo-Pacific reef-building coral Acropora millepora. We chose two physiologically different populations that associate respectively with one thermo-tolerant (Symbiodinium clade D) and one less tolerant symbiont type (Symbiodinium C2). In both symbiont types, pulse amplitude modulated (PAM) fluorometry and high performance liquid chromatography (HPLC) analysis revealed significant heritabilities for traits related to both photosynthesis and photoprotective pigment profile. However, quantitative real-time polymerase chain reaction (qRT-PCR) assays showed a lack of heritability in both coral host populations for their own expression of fundamental stress genes. Coral colony growth, contributed to by both symbiotic partners, displayed heritability. High heritabilities for functional key traits of algal symbionts, along with their short clonal generation time and high population sizes allow for their rapid thermal adaptation. However, the low overall heritability of coral host traits, along with the corals' long generation time, raise concern about the timely adaptation of the coral-algal symbiosis in the face of continued rapid climate warming.

Csaszar, Nikolaus B. M.; Ralph, Peter J.; Frankham, Richard; Berkelmans, Ray; van Oppen, Madeleine J. H.

2010-01-01

99

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

100

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

101

Biogeochemical characteristics of Siberia's Kolyma River watershed in relation to climate warming and permafrost degradation  

NASA Astrophysics Data System (ADS)

The Kolyma River in northeast Siberia, one of the six largest rivers entering the Arctic Ocean, is draining a region experiencing significant climate warming and is expected to undergo ever further warming over the coming century. The Kolyma River watershed is underlain with vast deposits of Pleistocene-aged loess known as Yedoma, which is associated with ice-rich continuous permafrost and organic carbon-rich soils. When these Yedoma permafrost soils thaw under warming conditions, carbon can be released to the atmosphere as CH4 and CO2, but also to nearby lakes, streams, and rivers as dissolved organic carbon (DOC). In July 2008, we conducted a survey of the Kolyma watershed to describe biogeochemical characteristics of water in streams and rivers draining a diverse set of subwatersheds, as well as longitudinal patterns in the Kolyma mainstem itself. Forty-two water samples were analyzed for pH, conductivity, dissolved oxygen (DO), and UV light absorbance at 254 nm (UV-254; a proxy for DOC concentrations and characteristics). We focus here primarily on UV-254, as the processing and transport of DOC in streams and rivers under a warming climate in this region may have globally significant implications for carbon cycling. GIS analyses show that UV-254 is dependent upon watershed area and land cover type (e.g., tundra, forested upland, or wetland), where UV-254 (and thereby DOC concentration) is higher in smaller, wetland- dominated watersheds. Overall, we find clear spatial variation in UV-254 of waters throughout the Kolyma River watershed, indicating that variability in watershed characteristics and location in the landscape strongly impact DOC concentrations and characteristics. Establishing these relationships is critical for predicting how future climate warming may ultimately impact the flux of DOC to the Arctic Ocean. This study is the result of an undergraduate field experience called The Polaris Project (www.thepolarisproject.org), which will continue through the summers of 2009 and 2010.

Willis, K. S.; Abbott, K. R.; Bulygina, E.; Frey, K. E.; Holmes, R. M.; Schade, J. D.

2008-12-01

102

A physiological trait-based approach to predicting the responses of species to experimental climate warming.  

PubMed

Physiological tolerance of environmental conditions can influence species-level responses to climate change. Here, we used species-specific thermal tolerances to predict the community responses of ant species to experimental forest-floor warming at the northern and southern boundaries of temperate hardwood forests in eastern North America. We then compared the predictive ability of thermal tolerance vs. correlative species distribution models (SDMs) which are popular forecasting tools for modeling the effects of climate change. Thermal tolerances predicted the responses of 19 ant species to experimental climate warming at the southern site, where environmental conditions are relatively close to the ants' upper thermal limits. In contrast, thermal tolerances did not predict the responses of the six species in the northern site, where environmental conditions are relatively far from the ants' upper thermal limits. Correlative SDMs were not predictive at either site. Our results suggest that, in environments close to a species' physiological limits, physiological trait-based measurements can successfully forecast the responses of species to future conditions. Although correlative SDMs may predict large-scale responses, such models may not be accurate for predicting site-level responses. PMID:23236901

Diamond, Sarah E; Nichols, Lauren M; McCoy, Neil; Hirsch, Christopher; Pelini, Shannon L; Sanders, Nathan J; Ellison, Aaron M; Gotelli, Nicholas J; Dunn, Robert R

2012-11-01

103

Frequently Asked Questions About Global Warming and Climate Change: Back to Basics.  

National Technical Information Service (NTIS)

The Earths climate is changing. In most places, average temperatures are rising. Scientists have observed a warming trend beginning around the late 1800s. The most rapid warming has occurred in recent decades. Most of this recent warming is very likely th...

2009-01-01

104

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

Microsoft Academic Search

Concern regarding the ecological impact of rapid global warming has encouraged research on climate-induced changes in biological systems. Critical problems, still poorly understood, are the potential for rapid adaptive responses and their genetic costs to populations. The O chromosomal polymorphisms of Drosophila subobscura have been monitored at a southern Palearctic locality experiencing sustained climate warming since the mid-1970s. Observations suggest

Francisco Rodríguez-Trelles; Miguel A. Rodríguez

1998-01-01

105

Potential Effects of Global Climate Warming on the Growth and Prey Consumption of Great Lakes Fish  

Microsoft Academic Search

We used fish bioenergetics models to assess the effect ofglobal climate warming on the growth and prey consumption of warm-, cool-, and coldwater fishes at three sites spanning the range of thermal environments in the Great Lakes. Historical air and water temperature data and projected air temperature changes from three global climate models were used as input to regression models,

David K. Hill; John J. Magnuson

1990-01-01

106

Geoengineering the Climate: Approaches to Counterbalancing Global Warming  

NASA Astrophysics Data System (ADS)

For the past two hundred years, the inadvertent release of carbon dioxide and other radiatively active gases and aerosols, particularly as a result of combustion of fossil fuels and changes in land cover, have been contributing to global climate change. Global warming to date is approaching 1°C, and this is being accompanied by reduced sea ice, rising sea level, shifting ecosystems and more. Rather than sharply curtailing use of fossil fuels in order to reduce CO2 emissions and eventually eliminate the net human influence on global climate, a number of approaches have been suggested that are intended to advertently modify the climate in a manner to counter-balance the warming influence of greenhouse gas emissions. One general type of approach is carbon sequestration, which focuses on capturing the CO2 and then sequestering it underground or in the ocean. This can be done at the source of emission, by pulling the CO2 out of the atmosphere through some chemical process, or by enhancing the natural processes that remove CO2 from the atmosphere, for example by fertilizing the oceans with iron. A second general approach to geoengineering the climate is to lower the warming influence of the incoming solar radiation by an amount equivalent to the energy captured by the CO2-induced enhancement of the greenhouse effect. Proposals have been made to do this by locating a deflector at the Earth-Sun Lagrange point, lofting many thousands of near-Earth mirrors, injecting aerosols into the stratosphere, or by increasing the surface albedo. A third general approach is to alter natural Earth system processes in ways that would counterbalance the effects of the warming. Among suggested approaches are constructing dams to block various ocean passages, oceanic films to limit evaporation and water vapor feedback, and even, at small scale, to insulate mountain glaciers to prevent melting. Each of these approaches has its advantages, ranging from simplicity to reversibility, and disadvantages, ranging from costs for implementation to associated inadvertent negative environmental consequences. Unless implemented as only a bridging effort, geoengineering would require diversion of substantial, and even growing, resources from the effort to move away from reliance on fossil fuels. Because the lifetime of the excess CO2 in the atmosphere is so long, such efforts would generally need to be maintained for centuries by future generations to avoid a relatively rapid increase in global average temperature, even after emissions of CO2 had eventually been halted. In that such approaches are also fraught with uncertainties, there has been very little study of the details of how such approaches might be pursued and of their overall advertent and inadvertent consequences, leaving the area open to ongoing consideration of sometimes rather speculative possibilities.

MacCracken, M. C.

2005-12-01

107

Climatic warming increases voltinism in European butterflies and moths  

PubMed Central

Climate change is altering geographical ranges, population dynamics and phenologies of many organisms. For ectotherms, increased ambient temperatures frequently have direct consequences for metabolic rates, activity patterns and developmental rates. Consequently, in many insect species both an earlier beginning and prolongation of seasonal duration occurred in parallel with recent global warming. However, from an ecological and evolutionary perspective, the number of generations (voltinism) and investment into each generation may be even more important than seasonality, since an additional generation per unit time may accelerate population growth or adaptation. Using a dataset extending back to the mid-nineteenth century, I report changes in the voltinism of butterfly and moth species of Central Europe. A significant proportion of 263 multi-voltine species showed augmented frequency of second and subsequent generations relative to the first generation in a warm period since 1980, and 44 species even increased the number of generations after 1980. Expected ecological consequences are diverse. Since multi-voltinism has been linked to insect outbreaks they include an increase in the abundance of herbivorous pests of agriculture and forestry. However, disruption of the developmental synchrony associated with multi-voltinism and host plant phenology may also reduce fitness, potentially having unexpected consequences for species of conservation concern. The ability of species to adapt evolutionarily to a changing environment may be facilitated by increased voltinism.

Altermatt, Florian

2010-01-01

108

Climatic warming increases voltinism in European butterflies and moths.  

PubMed

Climate change is altering geographical ranges, population dynamics and phenologies of many organisms. For ectotherms, increased ambient temperatures frequently have direct consequences for metabolic rates, activity patterns and developmental rates. Consequently, in many insect species both an earlier beginning and prolongation of seasonal duration occurred in parallel with recent global warming. However, from an ecological and evolutionary perspective, the number of generations (voltinism) and investment into each generation may be even more important than seasonality, since an additional generation per unit time may accelerate population growth or adaptation. Using a dataset extending back to the mid-nineteenth century, I report changes in the voltinism of butterfly and moth species of Central Europe. A significant proportion of 263 multi-voltine species showed augmented frequency of second and subsequent generations relative to the first generation in a warm period since 1980, and 44 species even increased the number of generations after 1980. Expected ecological consequences are diverse. Since multi-voltinism has been linked to insect outbreaks they include an increase in the abundance of herbivorous pests of agriculture and forestry. However, disruption of the developmental synchrony associated with multi-voltinism and host plant phenology may also reduce fitness, potentially having unexpected consequences for species of conservation concern. The ability of species to adapt evolutionarily to a changing environment may be facilitated by increased voltinism. PMID:20031988

Altermatt, Florian

2009-12-23

109

The land-ocean surface warming contrast in simulations of climate change with an idealized GCM  

NASA Astrophysics Data System (ADS)

Climate models robustly predict that surface temperatures will increase to a greater extent over land than over ocean under global warming, an effect known as the "land-ocean warming contrast". The enhanced warming over land is not solely a transient effect due to the different thermal inertias of the land and ocean, but rather it is a fundamental response of the climate system that persists in the equilibrium response of the system. We develop a theory, based on moist adiabatic lapse rates, that allows for the estimation of the magnitude of the warming contrast. Our analysis shows that the temperature difference between land and ocean regions increases monotonically as the climate warms, but that the amplification factor, defined as the ratio of land surface to ocean surface warming, has a maximum value for temperatures corresponding to the present-day climate. We evaluate this theory over a wide range of climates using idealized GCM simulations. The land surface hydrology is described by a simple bucket model, and we prescribe various land configurations with a mixed-layer ocean elsewhere. The warming contrast is found to be confined to low and middle latitudes and generally decreases poleward outside of the Tropics. The magnitude of the contrast is larger for zonal land bands than for continents with finite zonal extent. Increasing aridity leads to a larger warming contrast. At low latitudes and in cold or moderately warm climates, the warming contrast is well described by our theory, although it is important to account for variability in near-surface relative humidity over land. In very warm and/or very arid climates, the assumption of moist adiabatic lapse rates is inadequate over land. Consequently, a complete understanding of the warming contrast is inhibited by the need for a theory of lapse rates in both tropical and extratropical dynamical regimes and in arid and moist environments.

Byrne, M. P.; O'Gorman, P. A.

2011-12-01

110

How much do precipitation extremes change in a warming climate?  

NASA Astrophysics Data System (ADS)

Daily data from reanalyses of the European Centre for Medium-Range Weather Forecasts (ECMWF) and the National Centers for Environmental Prediction (NCEP) are analyzed to study changes in precipitation intensity with respect to global mean temperature. The results are in good agreement with those derived from the Global Precipitation Climatology Project (GPCP) data by Liu et al. (2009), providing an independent verification for large changes in the precipitation extremes: about 100% increase for the annual top 10% heavy precipitation and about 20% decrease for the light and moderate precipitation for one degree warming in the global temperature. These changes can substantially increase the risk of floods as well as droughts, thus severely affecting the global ecosystems. Atmospheric models used in the reanalysis mode, with the benefit of observed wind and moisture fields, appear to be capable of realistically simulating the change of precipitation intensity with global temperature. In comparison, coupled climate models are capable of simulating the shape of the change in precipitation intensity, but underestimate the magnitude of the change by about one order of magnitude. The most likely reason of the underestimation is that the typical spatial resolution of climate models is too coarse to resolve atmospheric convection.

Shiu, Chein-Jung; Liu, Shaw Chen; Fu, Congbin; Dai, Aiguo; Sun, Ying

2012-09-01

111

Can Regional Climate Models Improve Warm Season Forecasts in the North American Monsoon Region?  

Microsoft Academic Search

The goal of this work is to improve warm season forecasts in the North American Monsoon Region. To do this, we are dynamically downscaling warm season CFS (Climate Forecast System) reforecasts from 1982-2005 for the contiguous U.S. using the Weather Research and Forecasting (WRF) regional climate model. CFS is the global coupled ocean-atmosphere model used by the Climate Prediction Center

F. Dominguez; C. L. Castro

2009-01-01

112

An explanation for the difference between twentieth and twenty-first century land-sea warming ratio in climate models  

NASA Astrophysics Data System (ADS)

A land-sea surface warming ratio (or ?) that exceeds unity is a robust feature of both observed and modelled climate change. Interestingly, though climate models have differing values for ?, it remains almost time-invariant for a wide range of twenty-first century climate transient warming scenarios, while varying in simulations of the twentieth century. Here, we present an explanation for time-invariant land-sea warming ratio that applies if three conditions on radiative forcing are met: first, spatial variations in the climate forcing must be sufficiently small that the lower free troposphere warms evenly over land and ocean; second, the temperature response must not be large enough to change the global circulation to zeroth order; third, the temperature response must not be large enough to modify the boundary layer amplification mechanisms that contribute to making ? exceed unity. Projected temperature changes over this century are too small to breach the latter two conditions. Hence, the mechanism appears to show why both twenty-first century and time-invariant CO2 forcing lead to similar values of ? in climate models despite the presence of transient ocean heat uptake, whereas twentieth century forcing—which has a significant spatially confined anthropogenic tropospheric aerosol component that breaches the first condition—leads to modelled values of ? that vary widely amongst models and in time. Our results suggest an explanation for the behaviour of ? when climate is forced by other regionally confined forcing scenarios such as geo-engineered changes to oceanic clouds. Our results show how land-sea contrasts in surface and boundary layer characteristics act in tandem to produce the land-sea surface warming contrast.

Joshi, M. M.; Lambert, F. H.; Webb, M. J.

2013-10-01

113

Energetic contribution potential of building-integrated photovoltaics on airports in warm climates  

SciTech Connect

Especially in warm climates, a considerable fraction of the electricity demand in commercial buildings is due to the intensive use of air-conditioning systems. Airport buildings in sunny and warm regions present a perfect match between energy demand and solar resource availability. Airport buildings are also typically large and horizontal, isolated and free of shading, and have a great potential for the integration of solar photovoltaic (PV) systems. In this work, we assess the potential impact in energy demand reduction at the Florianopolis International Airport in Brazil (27 S, 48 W) with the use of building-integrated photovoltaic (BIPV) systems. We analyse the building's hourly energy consumption and solar irradiation data, to assess the match between energy demand and potential generation, and we estimate the PV power necessary to supply both the total amount and fractions of the annual energy demand. Our results show that the integration of PV systems on airport buildings in warm climates can supply the entire electric power consumption of an airport complex, in line with the general concept of a zero-energy building (ZEB). (author)

Ruether, Ricardo [LabEEE - Laboratorio de Eficiencia Energetica em Edificacoes, UFSC - Universidade Federal de Santa Catarina, Caixa Postal 476, Florianopolis, SC 88040-900 (Brazil); LABSOLAR - Laboratorio de Energia Solar, UFSC - Universidade Federal de Santa Catarina, Caixa Postal 476, Florianopolis, SC 88040-900 (Brazil); Braun, Priscila [LabEEE - Laboratorio de Eficiencia Energetica em Edificacoes, UFSC - Universidade Federal de Santa Catarina, Caixa Postal 476, Florianopolis, SC 88040-900 (Brazil)

2009-10-15

114

Climate warming revealed by englacial temperatures at Col du Dôme (4250 m, Mont Blanc area)  

NASA Astrophysics Data System (ADS)

Temperatures were measured in two deep boreholes drilled at the same location in the ice at Col du Dôme (4250 m) in 1994 and 2005, providing clear evidence of atmospheric warming. The 1994 temperature profile was already far from steady state conditions. Results from a heat transfer model reveal that the englacial temperature increase cannot be explained solely by atmospheric temperature rise. The latent heat produced by the refreezing of surface meltwater below the surface also contributes to the englacial temperature increase. Although surface melting is normally very low at this altitude, this contribution became significant after 1980 for temperatures at the top of the borehole. Simulations for different climatic scenarios show that glaciated areas located between 3500 and 4250 m could become temperate in the future. This warming could have a major impact on the stability of hanging glaciers frozen to their beds if the melting point is reached.

Vincent, Christian; Le Meur, Emmanuel; Six, Delphine; Possenti, Philippe; Lefebvre, Eric; Funk, Martin

2007-08-01

115

Assessing the strength of regional changes in near-surface climate associated with a global warming of 2 °C  

NASA Astrophysics Data System (ADS)

The objective of Article 2 of the United Nations Framework Convention on Climate Change formulated in 1992 is "to achieve stabilization of greenhouse gas concentrations in the atmosphere that would prevent dangerous anthropogenic interference with the climate system". In accordance with this, the Council of the Ministers for the Environment in the European Union laid down in a statement dated October 17, 2002, that in order to obtain this objective "global efforts should be guided by a long-term objective of a global temperature increase of 2 °C over pre-industrial levels and a stabilization of CO2 concentrations below 550 ppm.". In this study, the strength of the regional changes in near-surface climate associated with a global warming of 2 °C with respect to pre-industrial times is assessed, distinguishing between 26 different regions. Also, the strength of these regional changes in climate is compared to the strength of the respective changes associated with a markedly stronger global warming exceeding 4.5 °C. The magnitude of the regional changes in climate is estimated by means of a normalized regional climate change index, which considers changes in the mean as well as changes in the interannual variability of both near-surface temperature and precipitation. This index is particularly suited for comparing both the strength of the climatic changes in the different regions with each other and the strength of the changes in regional climate associated with the relatively weak global warming of 2° C with the strength of the respective changes related to a markedly stronger global warming exceeding 4.5 °C for individual regions. While the first comparison highlights those regions that are especially vulnerable to climatic changes, the second indicates to which extent the strength of the regional changes in climate is characterized by a non-linear behaviour, considering the magnitude of the underlying global warming. The study is based on two sets of four ensemble simulations with the ECHAM5/MPI-OM coupled climate model, each starting from different initial conditions. In one set of simulations (1860-2200), the greenhouse gas concentrations and sulphate aerosol load have been prescribed according to observations until 2000 and according to the SRES A1B scenario after 2000. In the other set of simulations (2020-2200), the greenhouse gas concentrations and sulphate aerosol load have been prescribed in such a way that the simulated global warming did not exceed 2 °C with respect to pre-industrial times.

May, Wilhelm

2010-05-01

116

[Impacts of climate warming on nine element contents in Mongolian drug Agi using ICP-AES].  

PubMed

Global warming has become a fact of life, and the night temperature increase higher than during the day. In the present research, to explore the effects of climate warming on element contents of plants, ICP-AES was used for the direct determination of nine kinds of element contents of reproductive branches and vegetative branches of the Mongolian drug Agi, which grew in the day, night and diurnal warming field. The results of the study show that the responses of reproductive branches and vegetative branches to day, night and diurnal warming were not significant different, but the negative response was greater than the positive response. The effects of day warming on the element contents were not significant, but night warming lower the contents of Al, Fe and Mn significantly. There was interaction between day warming and night warming. PMID:23586259

Borjigidai, Almaz; Xi, Yi; Li, Ya-Wei; Zhuang, Li; Gao, Qing-Zhu; Huang, Yong-Mei; Pang, Zong-Ran; Cui, Jian

2013-01-01

117

The Medieval Warm Period, the Little Ice Age and simulated climatic variability  

NASA Astrophysics Data System (ADS)

The CSIRO Mark 2 coupled global climatic model has been used to generate a 10,000-year simulation for ‘present’ climatic conditions. The model output has been analysed to identify sustained climatic fluctuations, such as those attributed to the Medieval Warm Period (MWP) and the Little Ice Age (LIA). Since no external forcing was permitted during the model run all such fluctuations are attributed to naturally occurring climatic variability associated with the nonlinear processes inherent in the climatic system. Comparison of simulated climatic time series for different geographical locations highlighted the lack of synchronicity between these series. The model was found to be able to simulate climatic extremes for selected observations for century timescales, as well as identifying the associated spatial characteristics. Other examples of time series simulated by the model for the USA and eastern Russia had similar characteristics to those attributed to the MWP and the LIA, but smaller amplitudes, and clearly defined spatial patterns. A search for the frequency of occurrence of specified surface temperature anomalies, defined via duration and mean value, revealed that these were primarily confined to polar regions and northern latitudes of Europe, Asia and North America. Over the majority of the oceans and southern hemisphere such climatic fluctuations could not be sustained, for reasons explained in the paper. Similarly, sustained sea ice anomalies were mainly confined to the northern hemisphere. An examination of mechanisms associated with the sustained climatic fluctuations failed to identify a role for the North Atlantic Oscillation, the El Niño-Southern Oscillation or the Pacific Decadal Oscillation. It was therefore concluded that these fluctuations were generated by stochastic processes intrinsic to the nonlinear climatic system. While a number of characteristics of the MWP and the LIA could have been partially caused by natural processes within the climatic system, the inability of the model to reproduce the observed hemispheric mean temperature anomalies associated with these events indicates that external forcing must have been involved. Essentially the unforced climatic system is unable to sustain the generation of long-term climatic anomalies.

Hunt, B. G.

2006-12-01

118

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

119

Using Long-Term Experimental Warming To Distinguish Vegetation Responses To Warming From Other Environmental Drivers Related To Climate Change  

NASA Astrophysics Data System (ADS)

Long term studies of vegetation change throughout the tundra biome show increases in the height, canopy extent and dominance of vascular vegetation versus bryophytes and lichens, with mixed responses of the dominant shrub and graminoid growth forms. Increases in vascular vegetation are recorded for sites with and without measurable climatic warming over recent decades, but with other potential drivers, i.e., increased summer precipitation. Experimental warming of tundra vegetation at Toolik Lake, Alaska shows a clear increase in shrub abundance relative to graminoids, with correlated higher NDVI values, increasing canopy heights, and thaw depths. Responses were similar between moist and dry tundra vegetation, with greater responses in moist vegetation. NDVI, with its ability to distinguish shrub from graminoid vegetation, may be a tool to distinguish fine scale differences in the response of tundra vegetation to climatic change, i.e., shifting balances of shrub and graminoid relative abundances that may be related to distinct climatic change drivers.

Gould, W. A.; Welker, J. M.; Mercado-Díaz, J. A.; Anderson, A.; Menken, M.

2010-12-01

120

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

121

Global Warming and Our Changing Climate: Answers to Frequently Asked Questions.  

National Technical Information Service (NTIS)

A warming trend has been recorded since the late 19th century, with the most rapid warming occurring over the past two decades. If emissions of greenhouse gases continue unabated, scientists say we may change global temperature and our planets climate at ...

2000-01-01

122

Biogeochemical characteristics of Siberia's Kolyma River watershed in relation to climate warming and permafrost degradation  

Microsoft Academic Search

The Kolyma River in northeast Siberia, one of the six largest rivers entering the Arctic Ocean, is draining a region experiencing significant climate warming and is expected to undergo ever further warming over the coming century. The Kolyma River watershed is underlain with vast deposits of Pleistocene-aged loess known as Yedoma, which is associated with ice-rich continuous permafrost and organic

K. S. Willis; K. R. Abbott; E. Bulygina; K. E. Frey; R. M. Holmes; J. D. Schade

2008-01-01

123

Assessment of climatic warming using a model of forest species migration  

Microsoft Academic Search

Significant shifts in plant species ranges are anticipated next century if climate warms due to greenhouse gas emissions. The magnitude of the projected warming is considerable; the rate at which it is predicted to occur is unprecedented. There is genuine reason for concern that the extent of the range shifts will exceed the dispersal abilities of many plant species, especially

James M. Dyer

1995-01-01

124

How do weather characteristics change in a warming climate?  

NASA Astrophysics Data System (ADS)

The possible change in the characteristics of weather in the future should be considered as important as the mean climate change because the increasing risk of extremes is related to the variability on daily time scales. The weather characteristics can be represented by the climatological mean interdiurnal (day-to-day) variability (MIDV). This paper first assessed the phase five of the Coupled Model Intercomparison Project coupled climate models' capability to represent MIDV for the surface maximum and minimum temperature, surface wind speed and precipitation under the present climate condition. Based on the assessment, we selected three best models for projecting future change. We found that the future changes in MIDV are characterized by: (a) a marked reduction in surface maximum and minimum temperature over high latitudes during the cold season; (b) a stronger reduction in the surface minimum temperature than in the maximum temperature; (c) a reduction in surface wind speed over large parts of lands in Northern Hemisphere (NH) during NH spring; (d) a noticeable increase in precipitation in NH mid-high latitudes in NH spring and winter, and in particular over East Asia throughout most of the year.

Kim, Ok-Yeon; Wang, Bin; Shin, Sun-Hee

2013-05-01

125

Testing Paradigms of Ecosystem Change under Climate Warming in Antarctica  

PubMed Central

Antarctic marine ecosystems have undergone significant changes as a result of human activities in the past and are now responding in varied and often complicated ways to climate change impacts. Recent years have seen the emergence of large-scale mechanistic explanations–or “paradigms of change”–that attempt to synthesize our understanding of past and current changes. In many cases, these paradigms are based on observations that are spatially and temporally patchy. The West Antarctic Peninsula (WAP), one of Earth’s most rapidly changing regions, has been an area of particular research focus. A recently proposed mechanistic explanation for observed changes in the WAP region relates changes in penguin populations to variability in krill biomass and regional warming. While this scheme is attractive for its simplicity and chronology, it may not account for complex spatio-temporal processes that drive ecosystem dynamics in the region. It might also be difficult to apply to other Antarctic regions that are experiencing some, though not all, of the changes documented for the WAP. We use qualitative network models of differing levels of complexity to test paradigms of change for the WAP ecosystem. Importantly, our approach captures the emergent effects of feedback processes in complex ecological networks and provides a means to identify and incorporate uncertain linkages between network elements. Our findings highlight key areas of uncertainty in the drivers of documented trends, and suggest that a greater level of model complexity is needed in devising explanations for ecosystem change in the Southern Ocean. We suggest that our network approach to evaluating a recent and widely cited paradigm of change for the Antarctic region could be broadly applied in hypothesis testing for other regions and research fields.

Melbourne-Thomas, Jessica; Constable, Andrew; Wotherspoon, Simon; Raymond, Ben

2013-01-01

126

Consistent large-scale temperature responses in warm and cold climates  

NASA Astrophysics Data System (ADS)

Climate-model simulations of the large-scale temperature responses to increased radiative forcing include enhanced land-sea contrast, stronger response at higher latitudes than in the tropics, and differential responses in warm and cool season climates to uniform forcing. Here we show that these patterns are also characteristic of model simulations of past climates. The differences in the responses over land as opposed to over the ocean, between high and low latitudes, and between summer and winter are remarkably consistent (proportional and nearly linear) across simulations of both cold and warm climates. Similar patterns also appear in historical observations and paleoclimatic reconstructions, implying that such responses are characteristic features of the climate system and not simple model artifacts, thereby increasing our confidence in the ability of climate models to correctly simulate different climatic states.

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

2013-05-01

127

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

128

Interference of extratropical surface climate anomalies induced by El Niño and stratospheric sudden warmings  

Microsoft Academic Search

The El Niño\\/Southern Oscillation (ENSO) and stratospheric sudden warmings (SSWs) each induce significant surface climate anomalies in Northern latitudes during winter. Nonetheless, possible connections between the impacts of the ENSO and SSWs remain relatively unexplored. Using both observational analysis and global climate model (GCM) experiments, we show that the impacts of El Niño and SSWs interfere over North America. The

Masakazu Taguchi; Dennis L. Hartmann

2005-01-01

129

Climatic warming, glacier recession and runoff from Alpine basins after the Little Ice Age maximum  

Microsoft Academic Search

Records of discharge of rivers draining Alpine basins with between 0 and ˜70% ice cover, in the upper Aare and Rhône catchments, Switzerland, for the period 1894-2006 have been examined together with climatic data for 1866-2006, with a view to assessing the effects on runoff from glacierized basins of climatic warming coupled with glacier recession following the Little Ice Age

David N. Collins

2008-01-01

130

Climatic warming, glacier recession and runoff from Alpine basins after the Little Ice Age maximum  

Microsoft Academic Search

Records of discharge of rivers draining Alpine basins with between 0 and ?? 70% ice cover, in the upper Aare and Rhone catchments, Switzerland, for the period 1894-2006 have been examined together with climatic data for 1866-2006, with a view to assessing the effects on runoff from glacierized basins of climatic warming coupled with glacier recession following the Little Ice

David N. Collins

2008-01-01

131

Alternatives 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 subjected 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; Kinfe Hailemariam; Nicola Stuber

2005-01-01

132

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

133

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; Rob P. Freckleton

2008-01-01

134

The Dynamic Response of the Greenland and Antarctic Ice Sheets to Multiple-Century Climatic Warming  

Microsoft Academic Search

New calculations were performed to investigate the combined response of the Greenland and Antarctic ice sheets to a range of climatic warming scenarios over the next millennium. Use was made of fully dynamic 3D thermomechanic ice sheet models, which were coupled to a two-dimensional climate model. The experiments were initialized with simulations over the last two glacial cycles to estimate

Philippe Huybrechts; Jan de Wolde

1999-01-01

135

Global Farm Animal Production and Global Warming: Impacting and Mitigating Climate Change  

Microsoft Academic Search

Background: The farm animal sector is the single largest anthropogenic user of land, contributing to many environmental problems, including global warming and climate change. Objectives: The aim of this study was to synthesize and expand upon existing data on the contribution of farm animal production to climate change. Methods: We analyzed the scientific literature on farm animal production and documented

Gowri Koneswaran; Danielle Nierenberg

2008-01-01

136

Climatic growing conditions of Jatropha curcas L  

Microsoft Academic Search

The massive investment in new jatropha plantations worldwide is not sufficiently based on a profound scientific knowledge of its ecology. In this article, we define the climatic conditions in its area of natural distribution by combining the locations of herbarium specimens with corresponding climatic information, and compare these conditions with those in 83 jatropha plantations worldwide.Most specimens (87%) were found

W. H. Maes; A. Trabucco; W. M. J. Achten; B. Muys

2009-01-01

137

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

Microsoft Academic Search

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

Aisling Dolan; Alan Haywood; Daniel Lunt; Daniel Hill

2010-01-01

138

From vegetation zones to climatypes: Effects of climate warming on ...  

Treesearch

US Forest Service ... Description: Evidence for global warming over the past 200 years is overwhelming, based on both direct weather observation and indirect physical and biological indicators such as retreating glaciers and snow/ice cover,  ...

139

Seasonal Climate Extremes : Mechanism, Predictability and Responses to Global Warming  

Microsoft Academic Search

Climate extremes are rarely occurring natural phenomena in the climate system. They often pose one of the greatest environmental threats to human and natural systems. Statistical methods are commonly used to investigate characteristics of climate extremes. The fitted statistical properties are often interpolated or extrapolated to give an indication of the likelihood of a certain event within a given period

M. E. Shongwe

2010-01-01

140

REGIONAL CLIMATE CHANGE SCENARIOS UNDER GLOBAL WARMING IN KAZAKHSTAN  

Microsoft Academic Search

The aim of this paper is to report on the development of regional climate change scenarios for Kazakhstan as the result of increasing of CO2 concentration in the global atmosphere. These scenarios are used in the assessment of climate change impacts on the agricultural, forest and water resources of Kazakhstan. Climate change scenarios for Kazakhstan to assess both long-term (2×

Olga V. Pilifosova; Irina B. Eserkepova; Svetlana A. Dolgih

1997-01-01

141

Persistent versus transient tree encroachment of temperate peat bogs: effects of climate warming and drought events.  

PubMed

Peatlands store approximately 30% of global soil carbon, most in moss-dominated bogs. Future climatic changes, such as changes in precipitation patterns and warming, are expected to affect peat bog vegetation composition and thereby its long-term carbon sequestration capacity. Theoretical work suggests that an episode of rapid environmental change is more likely to trigger transitions to alternative ecosystem states than a gradual, but equally large, change in conditions. We used a dynamic vegetation model to explore the impacts of drought events and increased temperature on vegetation composition of temperate peat bogs. We analyzed the consequences of six patterns of summer drought events combined with five temperature scenarios to test whether an open peat bog dominated by moss (Sphagnum) could shift to a tree-dominated state. Unexpectedly, neither a gradual decrease in the amount of summer precipitation nor the occurrence of a number of extremely dry summers in a row could shift the moss-dominated peat bog permanently into a tree-dominated peat bog. The increase in tree biomass during drought events was unable to trigger positive feedbacks that keep the ecosystem in a tree-dominated state after a return to previous 'normal' rainfall conditions. In contrast, temperature increases from 1 °C onward already shifted peat bogs into tree-dominated ecosystems. In our simulations, drought events facilitated tree establishment, but temperature determined how much tree biomass could develop. Our results suggest that under current climatic conditions, peat bog vegetation is rather resilient to drought events, but very sensitive to temperature increases, indicating that future warming is likely to trigger persistent vegetation shifts. PMID:23526779

Heijmans, Monique M P D; van der Knaap, Yasmijn A M; Holmgren, Milena; Limpens, Juul

2013-04-18

142

Global assessment of experimental climate warming on tundra vegetation: heterogeneity over space and time.  

PubMed

Understanding the sensitivity of tundra vegetation to climate warming is critical to forecasting future biodiversity and vegetation feedbacks to climate. In situ warming experiments accelerate climate change on a small scale to forecast responses of local plant communities. Limitations of this approach include the apparent site-specificity of results and uncertainty about the power of short-term studies to anticipate longer term change. We address these issues with a synthesis of 61 experimental warming studies, of up to 20 years duration, in tundra sites worldwide. The response of plant groups to warming often differed with ambient summer temperature, soil moisture and experimental duration. Shrubs increased with warming only where ambient temperature was high, whereas graminoids increased primarily in the coldest study sites. Linear increases in effect size over time were frequently observed. There was little indication of saturating or accelerating effects, as would be predicted if negative or positive vegetation feedbacks were common. These results indicate that tundra vegetation exhibits strong regional variation in response to warming, and that in vulnerable regions, cumulative effects of long-term warming on tundra vegetation - and associated ecosystem consequences - have the potential to be much greater than we have observed to date. PMID:22136670

Elmendorf, Sarah C; Henry, Gregory H R; Hollister, Robert D; Björk, Robert G; Bjorkman, Anne D; Callaghan, Terry V; Collier, Laura Siegwart; Cooper, Elisabeth J; Cornelissen, Johannes H C; Day, Thomas A; Fosaa, Anna Maria; Gould, William A; Grétarsdóttir, Járngerður; Harte, John; Hermanutz, Luise; Hik, David S; Hofgaard, Annika; Jarrad, Frith; Jónsdóttir, Ingibjörg Svala; Keuper, Frida; Klanderud, Kari; Klein, Julia A; Koh, Saewan; Kudo, Gaku; Lang, Simone I; Loewen, Val; May, Jeremy L; Mercado, Joel; Michelsen, Anders; Molau, Ulf; Myers-Smith, Isla H; Oberbauer, Steven F; Pieper, Sara; Post, Eric; Rixen, Christian; Robinson, Clare H; Schmidt, Niels Martin; Shaver, Gaius R; Stenström, Anna; Tolvanen, Anne; Totland, Orjan; Troxler, Tiffany; Wahren, Carl-Henrik; Webber, Patrick J; Welker, Jeffery M; Wookey, Philip A

2011-12-05

143

Climate model and proxy data constraints on ocean warming across the Paleocene–Eocene Thermal Maximum  

NASA Astrophysics Data System (ADS)

Constraining the greenhouse gas forcing, climatic warming and estimates of climate sensitivity across ancient large transient warming events is a major challenge to the palaeoclimate research community. Here we provide a new compilation and synthesis of the available marine proxy temperature data across the largest of these hyperthermals, the Paleocene–Eocene Thermal Maximum (PETM). This includes the application of consistent temperature calibrations to all data, including the most recent set of calibrations for archaeal lipid-derived palaeothermometry. This compilation provides the basis for an informed discussion of the likely range of PETM warming, the biases present in the existing record and an initial assessment of the geographical pattern of PETM ocean warming. To aid interpretation of the geographic variability of the proxy-derived estimates of PETM warming, we present a comparison of this data with the patterns of warming produced by high pCO2 simulations of Eocene climates using the Hadley Centre atmosphere-ocean general circulation model (AOGCM) HadCM3L. On the basis of this comparison and taking into account the patterns of intermediate-water warming we estimate that the global mean surface temperature anomaly for the PETM is within the range of 4 to 5 °C.

Dunkley Jones, Tom; Lunt, Daniel J.; Schmidt, Daniela N.; Ridgwell, Andy; Sluijs, Appy; Valdes, Paul J.; Maslin, Mark

2013-10-01

144

Doubled volatile organic compound emissions from subarctic tundra under simulated climate warming.  

PubMed

*Biogenic volatile organic compound (BVOC) emissions from arctic ecosystems are important in view of their role in global atmospheric chemistry and unknown feedbacks to global warming. These cold ecosystems are hotspots of climate warming, which will be more severe here than averaged over the globe. We assess the effects of climatic warming on non-methane BVOC emissions from a subarctic heath. *We performed ecosystem-based chamber measurements and gas chromatography-mass spectrometry (GC-MS) analyses of the BVOCs collected on adsorbent over two growing seasons at a wet subarctic tundra heath hosting a long-term warming and mountain birch (Betula pubescens ssp. czerepanovii) litter addition experiment. *The relatively low emissions of monoterpenes and sesquiterpenes were doubled in response to an air temperature increment of only 1.9-2.5 degrees C, while litter addition had a minor influence. BVOC emissions were seasonal, and warming combined with litter addition triggered emissions of specific compounds. *The unexpectedly high rate of release of BVOCs measured in this conservative warming scenario is far above the estimates produced by the current models, which underlines the importance of a focus on BVOC emissions during climate change. The observed changes have implications for ecological interactions and feedback effects on climate change via impacts on aerosol formation and indirect greenhouse effects. PMID:20456056

Faubert, Patrick; Tiiva, Päivi; Rinnan, Asmund; Michelsen, Anders; Holopainen, Jarmo K; Rinnan, Riikka

2010-04-28

145

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

146

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

147

Predicting CO2 and CH4 Emissions from the Active Layer in Response to Climate Warming  

NASA Astrophysics Data System (ADS)

Permafrost resides beneath 25% of the land in the northern hemisphere. Observations and models suggest that permafrost is warming and thawing, the active layer is thickening, and previously frozen old soil carbon is being converted and released as CH4 and CO2. GHG release amounts and rates are poorly constrained, as is the ratio between CH4 vs CO2. This ratio is important because CH4 is significantly more powerful as a greenhouse gas than is CO2. The arctic is projected to experience more precipitation, and perhaps more thermokarst lake formation, both of which could result in wetter conditions that favor CH4 production. At the same time, permafrost degradation could lead to thermal erosion and other landscape processes that enhance drainage and drier soil conditions that favor CO2 production. As the community continues to develop techniques to identify how the soil moisture status of the Arctic landscape will evolve, we are developing a model to assess how a range of soil moisture conditions, from very wet to very dry, will drive changes in GHG emissions as warming continues. Our numerical model (named ARCHY) is designed to simulate coupled surface and subsurface processes in freezing environments. It can operate in 1-D, 2-D or 3-D, is time-dependent, and includes vertical and lateral water and vapor and gas movement in heterogeneous soils and between soils and atmosphere, snow cover, heat transport, solar irradiation, precipitation, temperature, small scale topography, change of phase between water, ice and vapor, and three spatially distributed species of microbes including aerobes, anaerobes, and methanotrophs. A number of comparisons to data, including a set of soil temperatures and CO2 and CH4 emissions vs time at Toolik lake, as well as experiments on unsaturated flow in a domain with a freezing boundary, provide validation of the coupled thermal, hydrologic and microbiological processes in our model. We are using this calibrated model to contrast gas emissions from thawing permafrost over a range of soil moisture conditions, from a warmer but drier soil to a warmer and wetter soil column. The simulations spin up the soil column from present conditions to a warmer climate over several years. Significantly more CH4 evolution occurs in a wet, anoxic column compared to the present day climate, while a drier, oxic column shows more CO2 evolution but less CH4. Amounts and rates of emissions can be quantified and related to soil moisture contents and climate temperature increases.

Wilson, C. J.; Travis, B. J.; Ossola, I.

2011-12-01

148

Was Antarctica kept warm by subtropical waters in the Eocene? Part 2: Climate Model results  

NASA Astrophysics Data System (ADS)

Opening of the Tasmanian Gateway (TG) during the Eocene/Oligocene transition has long been invoked as the causal mechanism for the global climate shift from the "Hothouse" world of the early Cenozoic to the "Icehouse" world of the past 35 million years. ODP Leg 189 was designed to test the hypothesis that Antarctic cryospheric evolution resulted from the thermal isolation of Antarctica, caused by the opening of the TG. The proposed mechanism specifically being investigated was the cessation of poleward penetration of the heat-transporting, warm East Australian Current as the cause of the climate cooling. Five sites (1168-1172) were drilled to document paleoceanographic and paleoclimatic changes associated with the opening of the TG as Australia moved northward from Antarctica during the early Cenozoic. Demonstrating that this climatic transformation occurred synchronously with the rapid opening of TG is one of the major results of ODP Leg 189. To test the TG hypothesis we compare model fully coupled (ocean-atmosphere-sea ice-land) climate model results for Late Eocene conditions with proxy data and isotopic climate reconstructions. In this part, we demonstrate that (1) the East Australia Current (EAC) never extended far poleward, bending eastward around the northern edge of New Zealand instead, (2) even if this current had extended to Antarctica it is unlikely that turning the current off would have initiated glaciation, (3) that the proxy data agree with the paleocurrent predictions of the model, and (4) that the geologic record is not consistent with changes in the EAC as being the control on Antarctic glaciation. One alternative hypothesis --that the climate changes were driven by changes in greenhouse gas concentrations--is explored and appears consistent with the proxy data record. The model-predicted climate sensitivity and the proxy record of climate change allow us to estimate the most likely concentrations of carbon dioxide (or its radiative equivalent) through the Paleogene. The model is most consistent with values of pCO2 greater than 1120ppm in the early Eocene, values ~1120ppm in the middle Eocene, values ~560ppm in the late Eocene, and near modern values in the Oligocene.

Huber, M.; Brinkhuis, H.; Schellenberg, S. A.; Stickley, C. E.; Sluijs, A.; Warnaar, J.; Williams, G. L.; Exon, N. F.; Kennett, J. P.

2002-12-01

149

Climate Conditioning for the Learning Environment.  

ERIC Educational Resources Information Center

|Discusses heating, cooling, and ventilation for the classroom in relationship to students' learning abilities. It is designed to assist school boards, administrators, architects and engineers in understanding the beneficial effects of total climate control, and in evaluating the climate conditioning systems available for schools. Discussion…

Perkins and Will, Architects, Chicago, IL.

150

Modelling high latitude climates and ice sheets during the mid-Pliocene warm period  

Microsoft Academic Search

Reduction in the polar ice caps and associated climate feedbacks are implicated in the warming of pre- Quaternary palaeoclimates. General Circulation Model (GCM) simulations of the last such warm period, the mid- Pliocene (3.29-2.97 Ma), suggests global surface temperatures were between 1.4°C and 3.6°C warmer than today. However, the changes are amplified in the high latitudes, where the PRISM (Pliocene

D. J. Hill; A. M. Haywood; R. C. Hindmarsh; P. J. Valdes; D. J. Lunt

2007-01-01

151

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.; van, Geen, A.

2004-01-01

152

Can a new model better capture the stream temperature changes resulting from climate warming?  

NASA Astrophysics Data System (ADS)

Changes in snowmelt runoff due to climate change are expected to impact seasonal stream temperatures and associated biogeochemical processes. Many hydrologic models, such as the soil water assessment tool (SWAT), determine stream temperature based solely on a linear relationship with air temperature. However, in situations where warmer spring temperatures shift the timing and amount of snowmelt, the resulting stream temperature response cannot be adequately captured by the model. Thus, we present a new stream temperature model that reflects the combined influence of meteorological (air temperature) and hydrological conditions (streamflow, snowmelt, groundwater, surface runoff, and lateral soil flow) on monthly and seasonal water temperature within a watershed. The new stream temperature model is incorporated into SWAT and tested on 7 coastal and mountainous streams throughout the Western United States for which high quality flow and water temperature data were available. The new routine does not require input data beyond that already supplied to the model, can be calibrated with a limited number of parameters and achieves improved representation of observed daily stream temperature, as measured by several performance parameters. Our analysis suggests that the new stream temperature model calibration parameters are physically reasonable and the model is better able to capture stream temperature changes resulting from changes in hydro-climatological conditions, such as climate warming. An improved stream temperature model is the foundation for improved modeling accuracy for various in-stream biological and water quality processes.

Stewart-Frey, I. T.; Ficklin, D. L.; Luo, Y.; Maurer, E. P.

2011-12-01

153

Teaching about Climate Change: Cool Schools Tackle Global Warming.  

ERIC Educational Resources Information Center

Within the last couple of decades, the concentration of greenhouse gases in the atmosphere has increased significantly due to human activities. Today climate change is an important issue for humankind. This book provides a starting point for educators to teach about climate change, although there are obstacles caused by the industrialized…

Grant, Tim, Ed.; Littlejohn, Gail, Ed.

154

Evidence for global runoff increase related to climate warming  

Microsoft Academic Search

Ongoing global climatic change initiated by the anthropogenic release of carbon dioxide is a matter of intense debate. We focus both on the impact of these climatic changes on the global hydrological cycle and on the amplitude of the increase of global and continental runoff over the last century, in relation to measured temperature increases. In this contribution, we propose

David Labat; Yves Goddéris; Jean Luc Probst; Jean Loup Guyot

2004-01-01

155

Response of the North American Corn Belt to Climatic Warming.  

National Technical Information Service (NTIS)

The climate of the North American corn belt was characterized as part of an effort to estimate the effects of climatic change on that agricultural region. Heat and moisture characteristics of the current corn belt were first identified. Locations of those...

T. J. Blasing A. M. Solomon

1983-01-01

156

Travelling through a warming world: climate change and migratory species  

Microsoft Academic Search

Long-distance migrations are among the wonders of the natural world, but this multi-taxon review shows that the characteristics of species that undertake such movements appear to make them particularly vulnerable to detrimental impacts of climate change. Migrants are key components of biological systems in high latitude regions, where the speed and magnitude of climate change impacts are greatest. They also

A. Robinson; H. Q. P. Crick; J. A. Learmonth; I. M. D. Maclean; C. D. Thomas; F. Bairlein; M. C. Forchhammer; C. M. Francis; J. A. Gill; B. J. Godley; J. Harwood; G. C. Hays; B. Huntley; A. M. Hutson; G. J. Pierce; M. M. Rehfisch; D. W. Sims; M. C. Vieira dos Santos; T. H. Sparks; DA Stroud; M. E. Visser

2009-01-01

157

Teaching about Climate Change: Cool Schools Tackle Global Warming.  

ERIC Educational Resources Information Center

|Within the last couple of decades, the concentration of greenhouse gases in the atmosphere has increased significantly due to human activities. Today climate change is an important issue for humankind. This book provides a starting point for educators to teach about climate change, although there are obstacles caused by the industrialized…

Grant, Tim, Ed.; Littlejohn, Gail, Ed.

158

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

159

Sensitivity of boreal forests to possible climatic warming  

Microsoft Academic Search

General circulation models indicate substantial CO2 warming in high latitudes. In these regions, which include the boreal coniferous forests, the activity of ecosystems is largely controlled by temperature. The effective temperature sum (degree-days) is used in this study for describing the regional variability in the productivity of boreal ecosystems. Although the concept is simple, it takes into account two basic

Pekka Kauppi; Maximilian Posch

1985-01-01

160

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

161

CLIMATIC CONDITIONS IMPACT ON CANOLA CULTURAL PLANT GROWING IN TURKEY  

Microsoft Academic Search

Negative effect of climate conditions affecting many sectors ahead being agriculture on agricultural activities is felt in our country as well where global climate change is experienced. This situation needs breeding of alternative plants stronger than other products against to climate conditions, having multiple usage areas. By this aim; relation between special climate conditions of canola plant and climate conditions

Beyza KAYMAZ

162

Dividing climate change: global warming in the Indian mass media  

Microsoft Academic Search

Much research has now been conducted into the representation of climate change in the media. Specifically, the communication\\u000a of climate change from scientists and policy-makers to the public via the mass media has been a subject of major interest\\u000a because of its implications for creating national variation in public understanding of a global environmental issue. However,\\u000a to date, no study

Simon Billett

2010-01-01

163

Climate change in Norway: warm summers limit grouse reproduction  

Microsoft Academic Search

Grouse and vole numbers may peak after peaks in the seed crop of bilberry (Vaccinium myrtillus) because of reduced levels of feeding deterrents in bilberry plants. We predicted that grouse reproduction depends also on\\u000a summer (June–September) temperatures in the 2 previous years, because bilberry plants will be less exhausted after a high\\u000a seed crop in or after warm summers, and

Vidar SelasGeir; Geir A. Sonerud; Erik Framstad; John Atle Kålås; Sverre Kobro; Helge B. Pedersen; Tor K. Spidsø; Øystein Wiig

2011-01-01

164

Effects of climate warming on Olive and olive fly ( Bactrocera oleae (Gmelin)) in California and Italy  

Microsoft Academic Search

Climate change is expected to alter the geographic distribution and abundance of many species. Here we examine the potential\\u000a effects of climate warming on olive (Olea europaea) and olive fly (Bactrocera oleae) across the ecological zones of Arizona–California (AZ–CA) and Italy. A weather-driven physiologically-based demographic\\u000a model was developed from the extensive literature and used to simulate the phenology, growth and

Andrew Paul Gutierrez; Luigi Ponti; Q. A. Cossu

2009-01-01

165

Projection of global warming onto regional precipitation over Mongolia using a regional climate model  

Microsoft Academic Search

Climate change due to global warming is of concern to the public and may cause significant changes in the hydrological regimes in arid\\/semi-arid areas including Mongolia, which locates at a boundary between arid and humid regions. However, general circulation models (GCMs) are not sufficient to evaluate climate change on a regional-scale. In this study, two kinds of dynamical downscaling (DDS),

Tomonori Sato; Fujio Kimura; Akio Kitoh

2007-01-01

166

Assessment of the effects of climate warming on Great Lakes basin fishes  

Microsoft Academic Search

The authors combine information on the influence of temperature on the physiology and ecology of fishes with information on the interrelationships between climate and physical limnology for an initial assessment of the impact of future climate warming on fishes and their habitats in the Great Lakes basin. The predicted increase in mean annual air temperature of 3.2-4.8 °C is not

J. Donald Meisner; John L. Goodier; Henry A. Regier; Brian J. Shuter; W. Jack Christie

1987-01-01

167

Potential impacts of a warming climate on water availability in snow-dominated regions  

Microsoft Academic Search

All currently available climate models predict a near-surface warming trend under the influence of rising levels of greenhouse gases in the atmosphere. In addition to the direct effects on climate—for example, on the frequency of heatwaves—this increase in surface temperatures has important consequences for the hydrological cycle, particularly in regions where water supply is currently dominated by melting snow or

J. C. Adam; T. P. Barnett; D. P. Lettenmaier

2005-01-01

168

Broad range of 2050 warming from an observationally constrained large climate model ensemble  

NASA Astrophysics Data System (ADS)

Incomplete understanding of three aspects of the climate system--equilibrium climate sensitivity, rate of ocean heat uptake and historical aerosol forcing--and the physical processes underlying them lead to uncertainties in our assessment of the global-mean temperature evolution in the twenty-first century. Explorations of these uncertainties have so far relied on scaling approaches, large ensembles of simplified climate models, or small ensembles of complex coupled atmosphere-ocean general circulation models which under-represent uncertainties in key climate system properties derived from independent sources. Here we present results from a multi-thousand-member perturbed-physics ensemble of transient coupled atmosphere-ocean general circulation model simulations. We find that model versions that reproduce observed surface temperature changes over the past 50 years show global-mean temperature increases of 1.4-3K by 2050, relative to 1961-1990, under a mid-range forcing scenario. This range of warming is broadly consistent with the expert assessment provided by the Intergovernmental Panel on Climate Change Fourth Assessment Report, but extends towards larger warming than observed in ensembles-of-opportunity typically used for climate impact assessments. From our simulations, we conclude that warming by the middle of the twenty-first century that is stronger than earlier estimates is consistent with recent observed temperature changes and a mid-range `no mitigation' scenario for greenhouse-gas emissions.

Rowlands, Daniel J.; Frame, David J.; Ackerley, Duncan; Aina, Tolu; Booth, Ben B. B.; Christensen, Carl; Collins, Matthew; Faull, Nicholas; Forest, Chris E.; Grandey, Benjamin S.; Gryspeerdt, Edward; Highwood, Eleanor J.; Ingram, William J.; Knight, Sylvia; Lopez, Ana; Massey, Neil; McNamara, Frances; Meinshausen, Nicolai; Piani, Claudio; Rosier, Suzanne M.; Sanderson, Benjamin M.; Smith, Leonard A.; Stone, Dáithí A.; Thurston, Milo; Yamazaki, Kuniko; Hiro Yamazaki, Y.; Allen, Myles R.

2012-04-01

169

Internal structure of multiple Eocene climatic warming events from Demerara Rise  

NASA Astrophysics Data System (ADS)

It is widely believed that the extreme nature of the perturbation to carbon cycling across the Paleocene-Eocene Thermal Maximum (PETM) is indicative of a massive injection of carbon into the ocean-atmosphere from a buried, sedimentary source. The past ten years has witnessed the discovery of increasing numbers of less extreme, short-lived climatic warming events (‘hyperthermals’) punctuating the already warm ‘greenhouse’ climates of the early Palaeogene (~65 to 40 Myr ago). A 2.5 Myr-long benthic foraminiferal stable isotope record from Demerara Rise reveals multiple, previously unrecognised warming events across the early to middle Eocene transition (47.5 to 50 Myr ago). In contrast to the PETM, the smaller size, relatively short duration (~40 kyr), and faster recoveries of these less extreme events suggest that they were driven not by sedimentary-sourced carbon, but by redistribution of carbon from the readily exchangeable reservoirs at Earth’s surface. Here we present new, very high resolution bulk sediment stable isotope records and X-ray fluorescence (XRF) core scanning data across a number of prominent warming events. These new records enable comparison of the internal structure of these events, with implications for the processes involved in their genesis. Furthermore, estimates of biogenic barium indicate increases in export paleoproductivity during the recovery phases of these events, suggesting a role for the biosphere in providing a negative feedback to carbon cycle instability during past warm climates.

Kirtland, S. E.; Sexton, P. F.; Norris, R. D.; Westerhold, T.; Roehl, U.

2009-12-01

170

Oceanic Climate Change: Contributions of Heat Content, Temperature, and Salinity Trends to Global Warming  

Microsoft Academic Search

The World Ocean is the largest component of the global climate system, and changes to its heat content, temperature, and salinity have an enormous impact on the current global warming trend. In this paper, these physical changes are discussed in detail, including potential sources of change and spatial and temporal variability, as the observed trends are influenced by location as

Christopher M. Mirabito

171

Linking an ecosystem model and a landscape model to study forest species response to climate warming  

Microsoft Academic Search

No single model can address forest change from single tree to regional scales. We discuss a framework linking an ecosystem process model (linkages) with a spatial landscape model (landis) to examine forest species responses to climate warming for a large, heterogeneous landscape in northern Wisconsin, USA. Individual species response at the ecosystem scale was simulated with linkages, which integrates soil,

Hong S. He; David J. Mladenoff; Thomas R. Crow

1999-01-01

172

Northward migration of permafrost along the Mackenzie highway and climatic warming  

Microsoft Academic Search

Based on two field surveys of permafrost distribution, conducted 26 years apart, along the Mackenzie Highway south of Great Slave Lake, Canada, the southern limit of the sporadic discontinuous permafrost zone in the region has migrated northward by about 120 km. To substantiate that the disappearance of perennial frozen ground is largely caused by climatic warming, a detailed trend analysis

Y. T. John Kwong; T. Y. Gan

1994-01-01

173

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

174

Mechanisms for the land\\/sea warming contrast exhibited by simulations of climate change  

Microsoft Academic Search

The land\\/sea warming contrast is a phenomenon of both equilibrium and transient simulations of climate change: large areas of the land surface at most latitudes undergo temperature changes whose amplitude is more than those of the surrounding oceans. Using idealised GCM experiments with perturbed SSTs, we show that the land\\/sea contrast in equilibrium simulations is associated with local feedbacks and

Manoj M. Joshi; Jonathan M. Gregory; Mark J. Webb; David M. H. Sexton; Tim C. Johns

2008-01-01

175

Population decrease of Scirpophaga incertulas Walker (Lepidoptera Pyralidae) under climate warming.  

PubMed

Scirpophaga incertulas Walker is an important agricultural pest in Asia. Only few studies are available on its long-term population dynamics under climate warming. In this study, we used the linear and generalized additive models (GAMs) to analyze the historical dataset of >50 years on this pest at Xinfeng County of Jiangxi Province, China. The main objective of this study was to explore the effects of density (delayed) dependence and minimum annual temperature (MAT), which indirectly reflects climate warming, on the population dynamics of this pest. We found that both density dependence and MAT have significant influence on the annual population growth rate. The GAMs had relatively better applicability to the dataset than the linear models. Nonparametric model provided satisfactory goodness-of-fit (R(2) > 0.5). At Xinfeng County, the MAT had a significant effect on the annual population growth rate of S. incertulas. The annual population growth rate of S. incertulas decreased with increase in MAT. Therefore, S. incertulas population becomes smaller and smaller in Southern China due to climate warming. The current study has two contributions: (1) providing a suitable method for predicting the annual population growth rate of S. incertulas, and (2) demonstrating that climate warming could decrease the S. incertulas population. PMID:22408726

Shi, Peijian; Zhong, Ling; Sandhu, Hardev S; Ge, Feng; Xu, Xiaoming; Chen, Wei

2012-01-01

176

Population decrease of Scirpophaga incertulas Walker (Lepidoptera Pyralidae) under climate warming  

PubMed Central

Scirpophaga incertulas Walker is an important agricultural pest in Asia. Only few studies are available on its long-term population dynamics under climate warming. In this study, we used the linear and generalized additive models (GAMs) to analyze the historical dataset of >50 years on this pest at Xinfeng County of Jiangxi Province, China. The main objective of this study was to explore the effects of density (delayed) dependence and minimum annual temperature (MAT), which indirectly reflects climate warming, on the population dynamics of this pest. We found that both density dependence and MAT have significant influence on the annual population growth rate. The GAMs had relatively better applicability to the dataset than the linear models. Nonparametric model provided satisfactory goodness-of-fit (R2 > 0.5). At Xinfeng County, the MAT had a significant effect on the annual population growth rate of S. incertulas. The annual population growth rate of S. incertulas decreased with increase in MAT. Therefore, S. incertulas population becomes smaller and smaller in Southern China due to climate warming. The current study has two contributions: (1) providing a suitable method for predicting the annual population growth rate of S. incertulas, and (2) demonstrating that climate warming could decrease the S. incertulas population.

Shi, Peijian; Zhong, Ling; Sandhu, Hardev S; Ge, Feng; Xu, Xiaoming; Chen, Wei

2012-01-01

177

From the Cover: Impacts of climate warming on terrestrial ectotherms across latitude  

Microsoft Academic Search

The impact of anthropogenic climate change on terrestrial organisms is often predicted to increase with latitude, in parallel with the rate of warming. Yet the biological impact of rising temperatures also depends on the physiological sensitivity of organisms to temperature change. We integrate empirical fitness curves describing the thermal tolerance of terrestrial insects from around the world with the projected

Curtis A. Deutsch; Joshua J. Tewksbury; Raymond B. Huey; Kimberly S. Sheldon; Cameron K. Ghalambor; David C. Haak; Paul R. Martin

2008-01-01

178

Response to Comment on ``Global Genetic Change Tracks Global Climate Warming in Drosophila subobscura''  

Microsoft Academic Search

Rodríguez-Trelles and Rodríguez advocate standardizing old and new collections by climate rather than by calendar and also propose that some of our samples were biased by inappropriate timing. Their first suggestion applies to few species, and its implementation alters photoperiodic cues. Their second point is valid, but our conclusions are robust: Observed genetic changes reflect global warming, not sampling artifacts.

Joan Balanyà; Josep M. Oller; Raymond B. Huey; George W. Gilchrist; Luis Serra

2007-01-01

179

Potential Effects of Climatic Warming on the Water Resources of the Columbia River Basin.  

National Technical Information Service (NTIS)

The sensitivity of the Columbia River basin reservoir system to two alternative climate scenarios (+2C and +4C warming) was assessed by using a sequence of deterministic and stochastic models. Thirty eight years of daily streamflow were simulated for thre...

J. C. Sias D. P. Lettenmaier

1994-01-01

180

Climate warming is lowering levels of dissolved carbon in the Yukon River  

NSDL National Science Digital Library

Dissolved organic carbon (DOC) export, normalized to water discharge, during the growing season from 1978 to 1980 was compared with that taken from 2001 to 2003. It was found that climate warming on frozen soils increases the flow path, residence time, and microbial mineralization of DOC in the soil's active layer and groundwater, ultimately decreasing DOC export.

Al., Striegl E.; Agu

181

Response of Lena basin river runoff to recent and projected global climate warming  

Microsoft Academic Search

It follows from the results of calculations fulfilled that in the period of intensive warming of regional climate (beginning with the 1980s) the average annual air temperature rose very considerably, but heterogeneously over the territory of the Lena River basin. The most significant rise is observed in central, eastern and southern parts of the basin. The character of change of

Alexander Georgiadi; Irina Milyukova; Ekaterina Kashutina

2010-01-01

182

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...

183

Experimental climate warming decreases photosynthetic efficiency of lichens in an arid South African ecosystem.  

PubMed

Elevated temperatures and diminished precipitation amounts accompanying climate warming in arid ecosystems are expected to have adverse effects on the photosynthesis of lichen species sensitive to elevated temperature and/or water limitation. This premise was tested by artificially elevating temperatures (increase 2.1-3.8°C) and reducing the amounts of fog and dew precipitation (decrease 30.1-31.9%), in an approximation of future climate warming scenarios, using transparent hexagonal open-top warming chambers placed around natural populations of four lichen species (Xanthoparmelia austroafricana, X. hyporhytida , Xanthoparmelia. sp., Xanthomaculina hottentotta) at a dry inland site and two lichen species (Teloschistes capensis and Ramalina sp.) at a humid coastal site in the arid South African Succulent Karoo Biome. Effective photosynthetic quantum yields ([Formula: see text]) were measured hourly throughout the day at monthly intervals in pre-hydrated lichens present in the open-top warming chambers and in controls which comprised demarcated plots of equivalent open-top warming chamber dimensions constructed from 5-cm-diameter mesh steel fencing. The cumulative effects of the elevated temperatures and diminished precipitation amounts in the open-top warming chambers resulted in significant decreases in lichen [Formula: see text]. The decreases were more pronounced in lichens from the dry inland site (decline 34.1-46.1%) than in those from the humid coastal site (decline 11.3-13.7%), most frequent and prominent in lichens at both sites during the dry summer season, and generally of greatest magnitude at or after the solar noon in all seasons. Based on these results, we conclude that climate warming interacting with reduced precipitation will negatively affect carbon balances in endemic lichens by increasing desiccation damage and reducing photosynthetic activity time, leading to increased incidences of mortality. PMID:22057927

Maphangwa, Khumbudzo Walter; Musil, Charles F; Raitt, Lincoln; Zedda, Luciana

2011-11-06

184

Climatic warming in the Tibetan Plateau during recent decades  

Microsoft Academic Search

Adequate knowledge of climatic change over the Tibetan Plateau (TP) with an average elevation of more than 4000 m above sea level (a.s.l.) has been insufficient for a long time owing to the lack of sufficient observational data. In the present study, monthly surface air temperature data were collected from almost every meteorological station on the TP since their establishment.

Xiaodong Liu; Baode Chen

2000-01-01

185

Humidity critical for grass growth in warming climates  

Technology Transfer Automated Retrieval System (TEKTRAN)

Plant growth responses to climate change might be confounded by multi-factor changes such as temperature and vapor pressure deficit (VPD). The growth and water loss of tall fescue (Festuca arundinaccea Schreb.), a cool season grass, was measured over 6 weeks with independent control of temperature a...

186

Climate warming and the decline of amphibians and reptiles in Europe  

Microsoft Academic Search

ABSTRACT Aim,We,explore,the relationship between,current,European,distributions,of amphibian and reptile species and observed climate, and project species potential distributions into the future. Potential impacts of climate warming,are assessed by quantifying,the magnitude,and,direction of modelled,distributional shifts for every species. In particular we ask, first, what proportion of amphibian and reptile species are projected,to lose and,gain suitable climate,space in the future? Secondly, do species projections vary

M. B. Araújo; W. Thuiller; R. G. Pearson

2006-01-01

187

Simulated Changes in the Freezing Rain Climatology of North America under Global Warming Using a Coupled Climate Model  

Microsoft Academic Search

A precipitation typing algorithm was applied to climate model simulations in order to investigate the effect of global warming on the occurrence of freezing rain over North America. The model used in the study was the Canadian Centre for Climate Modelling and Analysis' CGCM3. Two realizations of the present-day (1981–2000) climate and two realizations of a global warming (2081–2100) simulation

Steven J. Lambert; Bjarne K. Hansen

2011-01-01

188

Permafrost degradation and methane: low risk of biogeochemical climate-warming feedback  

NASA Astrophysics Data System (ADS)

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, we examine the degradation of near-surface permafrost, temporal dynamics of inundation (lakes and wetlands) induced by hydro-climatic change, subsequent methane emission, and potential climate feedback. We find that increases in atmospheric CH4 and its radiative forcing, which result from the thawed, inundated emission sources, are small, particularly when weighed against human emissions. The additional warming, across the range of climate policy and uncertainties in the climate-system response, would be no greater than 0.1?° C by 2100. Further, for this temperature feedback to be doubled (to approximately 0.2?° C) by 2100, at least a 25-fold increase in the methane emission that results from the estimated permafrost degradation would be required. Overall, this biogeochemical global climate-warming feedback is relatively small whether or not humans choose to constrain global emissions.

Gao, Xiang; Schlosser, C. Adam; Sokolov, Andrei; Anthony, Katey Walter; Zhuang, Qianlai; Kicklighter, David

2013-09-01

189

Indirect chemical effects of methane on climate warming  

Microsoft Academic Search

METHANE concentrations in the atmosphere have increased from about 0.75 to 1.7 p.p.m.v. since pre-industrial times1,2. The current annual rate of increase of about 0.8% yr-1 (ref. 2) is due to increases in industrial and agricultural emissions. This increase in atmospheric methane concentrations not only influences the climate directly, but also indirectly through chemical reactions. Here we show that the

Jos Lelieveld; Paul J. Crutzen

1992-01-01

190

Personal efficacy, the information environment, and attitudes toward global warming and climate change in the United States.  

PubMed

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. PMID:18304110

Kellstedt, Paul M; Zahran, Sammy; Vedlitz, Arnold

2008-02-01

191

Permanent El Niño-like conditions during the Pliocene warm period.  

PubMed

During the warm early Pliocene (approximately 4.5 to 3.0 million years ago), the most recent interval with a climate warmer than today, the eastern Pacific thermocline was deep and the average west-to-east sea surface temperature difference across the equatorial Pacific was only 1.5 +/- 0.9 degrees C, much like it is during a modern El Niño event. Thus, the modern strong sea surface temperature gradient across the equatorial Pacific is not a stable and permanent feature. Sustained El Niño-like conditions, including relatively weak zonal atmospheric (Walker) circulation, could be a consequence of, and play an important role in determining, global warmth. PMID:15976271

Wara, Michael W; Ravelo, Ana Christina; Delaney, Margaret L

2005-06-23

192

How do climate warming and species richness affect CO2 fluxes in experimental grasslands?  

PubMed

This paper presents the results of 2 yr of CO(2) flux measurements on grassland communities of varying species richness, exposed to either the current or a warmer climate. We grew experimental plant communities containing one, three or nine grassland species in 12 sunlit, climate-controlled chambers. Half of these chambers were exposed to ambient air temperatures, while the other half were warmed by 3 degrees C. Equal amounts of water were added to heated and unheated communities, implying drier soils if warming increased evapotranspiration. Three main CO(2) fluxes (gross photosynthesis, above-ground and below-ground respiration) were measured multiple times per year and reconstructed hourly or half-hourly by relating them to their most important environmental driver. While CO(2) outputs through respiration were largely unchanged under warming, CO(2) inputs through photosynthesis were lowered, especially in summer, when heat and drought stress were higher. Above-ground CO(2) fluxes were significantly increased in multispecies communities, as more complementary resource use stimulated productivity. Finally, effects of warming appeared to be smallest in monocultures. This study shows that in a future warmer climate the CO(2) sink capacity of temperate grasslands could decline, and that such adverse effects are not likely to be mitigated by efforts to maintain or increase species richness. PMID:17635226

De Boeck, Hans J; Lemmens, Catherine M H M; Vicca, Sara; Van den Berge, Joke; Van Dongen, Stefan; Janssens, Ivan A; Ceulemans, Reinhart; Nijs, Ivan

2007-01-01

193

How does coldwave frequency in china respond to a warming climate?  

NASA Astrophysics Data System (ADS)

Under the background of a warming climate, regional climate responses may be different from place to place. How cold extreme events in China respond is still an open question. This study investigates responses of coldwave frequency (CWF) in China from observation and modeling perspectives. Observational evidences show that CWF significantly reduces across China during the warm period (1978-2009) in comparison with that during the cold period (1957-1977), concurrent with extreme value centers located in northern China during 1957-1977 and southern China during 1978-2009. The empirical orthogonal function (EOF) leading mode of CWF in the cold period is also dominant by an extreme value center prevailing over northern China, while the center exhibits a southward shift in the warm period. A seven-member multi-model ensemble (MME) from coupled model intercomparison project#3 (CMIP3) shows that southern China tends to experience more coldwaves than northern China in the twenty first century (2045-2064 and 2080-2099) under the global warming A1B forcing (with atmospheric CO2 concentration of 720 ppm). This feature can also be seen in the leading EOF mode of MME. These results indicate that the primary response of CWF to a warming climate may be the southward shift of the maximum loading center. The enhanced western Pacific Subtropical High and weakened Siberian High during 1978-2009 may result in anomalous southerlies which bring warm and wet air to southern China. Meanwhile cold and dry air is transported from the north via a "northwest pathway" to southern China. Under the joint action of these two air masses, coldwaves may easily generate in southern China as observed in recent extreme cold events in this region.

Ma, Tingting; Wu, Zhiwei; Jiang, Zhihong

2012-11-01

194

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

195

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

196

The detector of warmly isolation condition defects with an independent supply  

Microsoft Academic Search

Ways of construction of the detector of warmly isolation condition defects of heating systems DD1 are considered. The detector of defects DD1 is intended for the remote control and monitoring of a technical condition of warmly isolation of heating systems by measurement of impedance between an alarm wire and a surface of a steel pipe of a heating system. The

Ivan Prudyus; Jaroslav Kril; Volodymyr Storozh; Gennadiy Turkinov; Volodymyr Shkliarskyi

2012-01-01

197

A regional response in mean westerly circulation and rainfall to projected climate warming over Tasmania, Australia  

NASA Astrophysics Data System (ADS)

Coupled ocean-atmosphere general circulation models (GCMs) lack sufficient resolution to model the regional detail of changes to mean circulation and rainfall with projected climate warming. In this paper, changes in mean circulation and rainfall in GCMs are compared to those in a variable resolution regional climate model, the Conformal Cubic Atmospheric Model (CCAM), under a high greenhouse gas emissions scenario. The study site is Tasmania, Australia, which is positioned within the mid-latitude westerlies of the southern hemisphere. CCAM projects a different response in mean sea level pressure and mid-latitude westerly circulation to climate warming to the GCMs used as input, and shows greater regional detail of the boundaries between regions of increasing and decreasing rainfall. Changes in mean circulation dominate the mean rainfall response in western Tasmania, whereas changes to rainfall in the East Coast are less related to mean circulation changes. CCAM projects an amplification of the dominant westerly circulation over Tasmania and this amplifies the seasonal cycle of wet winters and dry summers in the west. There is a larger change in the strength than in the incidence of westerly circulation and rainfall events. We propose the regional climate model displays a more sensitive atmospheric response to the different rates of warming of land and sea than the GCMs as input. The regional variation in these results highlight the need for dynamical downscaling of coupled general circulation models to finely resolve the influence of mean circulation and boundaries between regions of projected increases and decreases in rainfall.

Grose, Michael R.; Corney, Stuart P.; Katzfey, Jack J.; Bennett, James C.; Holz, Gregory K.; White, Christopher J.; Bindoff, Nathaniel L.

2013-04-01

198

Is This Global Warming? Communicating the Intangibles of Climate Change  

NASA Astrophysics Data System (ADS)

Unlike weather, which is immediate, tangible, and relevant on a daily basis, climate change is long-term, slow to evolve, and often difficult to relate to the public's daily concerns. By explaining global-change research to wide and diverse audiences through a variety of vehicles, including publications, exhibits, Web sites, and television B-roll, UCAR has gained experience and perspective on the challenges involved. This talk will explore some of the lessons learned and some of the key difficulties that face global-change communicators, including: --The lack of definitive findings on regional effects of global change -- The long time frame in which global change plays out, versus the short attention span of media, the public, and policy makers --The use of weather events as news pegs (they pique interest, but they may not be good exemplars of global change and are difficult to relate directly to changes in greenhouse-gas emissions) --The perils of the traditional journalistic technique of point-counterpoint in discussing climate change --The presence of strong personal/political convictions among various interest groups and how these affect the message(s) conveyed

Warner, L.; Henson, R.

2004-05-01

199

The Possible Effect of Climate Warming on Northern Limits of Cropping System and Crop Yield in China  

Microsoft Academic Search

Significantly increasing temperature since the 1980s in China has become a consensus under the background of global climate change and how climate change affects agriculture or even cropping systems has attracted more and more attention from Chinese government and scientists. In this study, the possible effects of climate warming on the national northern limits of cropping systems, the northern limits

Xiao-guang YANG; Zhi-juan LIU; Fu CHEN

2011-01-01

200

Sensitivity of arctic summer sea ice coverage to global warming forcing: towards reducing uncertainty in arctic climate change projections  

Microsoft Academic Search

Substantial uncertainties have emerged in Arctic climate change projections by the fourth Intergovernmental Panel on Climate Change assessment report climate models. In particular, the models as a group considerably underestimate the recent accelerating sea ice reduction. To better understand the uncertainties, we evaluated sensitivities of summer sea ice coverage to global warming forcing in models and observations. The result suggests

Xiangdong Zhang

2010-01-01

201

Climate on Cable: The Nature and Impact of Global Warming Coverage on Fox News, CNN, and MSNBC  

Microsoft Academic Search

This study examines climate change coverage on the three major cable news channels and assesses the relationship between viewership of these channels and beliefs about global warming. Evidence from a content analysis of climate change coverage on Fox News, CNN, and MSNBC during 2007 and 2008 demonstrates that Fox takes a more dismissive tone toward climate change than CNN and

Lauren Feldman; Edward W. Maibach; Connie Roser-Renouf; Anthony Leiserowitz

2012-01-01

202

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

2013-03-01

203

Above- and belowground linkages in Sphagnum peatland: climate warming affects plant-microbial interactions.  

PubMed

Peatlands contain approximately one third of all soil organic carbon (SOC). Warming can alter above- and belowground linkages that regulate soil organic carbon dynamics and C-balance in peatlands. Here we examine the multiyear impact of in situ experimental warming on the microbial food web, vegetation, and their feedbacks with soil chemistry. We provide evidence of both positive and negative impacts of warming on specific microbial functional groups, leading to destabilization of the microbial food web. We observed a strong reduction (70%) in the biomass of top-predators (testate amoebae) in warmed plots. Such a loss caused a shortening of microbial food chains, which in turn stimulated microbial activity, leading to slight increases in levels of nutrients and labile C in water. We further show that warming altered the regulatory role of Sphagnum-polyphenols on microbial community structure with a potential inhibition of top predators. In addition, warming caused a decrease in Sphagnum cover and an increase in vascular plant cover. Using structural equation modelling, we show that changes in the microbial food web affected the relationships between plants, soil water chemistry, and microbial communities. These results suggest that warming will destabilize C and nutrient recycling of peatlands via changes in above- and belowground linkages, and therefore, the microbial food web associated with mosses will feedback positively to global warming by destabilizing the carbon cycle. This study confirms that microbial food webs thus constitute a key element in the functioning of peatland ecosystems. Their study can help understand how mosses, as ecosystem engineers, tightly regulate biogeochemical cycling and climate feedback in peatlands. PMID:23504838

Jassey, Vincent E J; Chiapusio, Geneviève; Binet, Philippe; Buttler, Alexandre; Laggoun-Défarge, Fatima; Delarue, Frédéric; Bernard, Nadine; Mitchell, Edward A D; Toussaint, Marie-Laure; Francez, André-Jean; Gilbert, Daniel

2012-12-15

204

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

205

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

206

The influence of climate change and the timing of stratospheric warmings on Arctic ozone depletion  

SciTech Connect

A three-dimensional model is presented to evaluate the influence of climatic change and increased carbon dioxide concentrations on ozone depletion in the Arctic region. Satellite data showing the time of stratospheric warmings during the winters of 1979-1992 is used in a series of idealized experiments where the timing of the warmings is varied by using different geopotential wave amplitudes. Results of the experiments indicate that for doubled atmospheric carbon dioxide levels, an ozone hole in the Arctic is more likely to develop during years where late stratospheric warming has occurred after a relatively quiescent winter. The validity of this model is dependent on the future composition and temperature of the stratosphere. 43 refs., 21 figs.

Austin, J. [Meteorological Office, Bracknell (United Kingdom); Butchart, N. [Hadley Centre for Climate Prediction and Research, Bracknell (United Kingdom)

1994-01-20

207

Cold ecosystems in a warmer climate: carbon fluxes at the alpine treeline under experimental soil warming  

NASA Astrophysics Data System (ADS)

The impact of climatic warming on the C balance of terrestrial ecosystems is uncertain because rising temperature increases both C gains through net primary production, but also respiratory C losses. 'Cold' ecosystems such as treeline ecotones will respond particularly sensitive to climatic changes because many processes are limited by temperature and soils store particular large amounts of labile soil organic matter. In our study, we investigate ecosystem responses to 9 years of elevated atmospheric CO2 and to 3 years of experimental soil warming by 4° C. The added CO2 contains another ?13C signature than normal air, which allows the tracing of new carbon through the plant and soil system. This provides new insight into carbon cycling at the treeline and it shows which C flux respond most sensitive to climatic changes. Results showed that soil warming increased soil CO2 effluxes instantaneously and persisted for at least three vegetation periods (+35-45%; +80 to 120 g C m y-1). In contrast, DOC leaching showed a negligible response of less than 5% increase. Annual C uptake of new shoots was not significantly affected by elevated soil temperatures, with a 10 to 20% increase for larch, pine, and dwarf shrubs, respectively, resulting in an overall increase in net C uptake by plants of 20 to 40 g C m-2y-1. The Q10 of 3.0 measured for soil respiration did not change compared to a three-year period before the warming treatment started, suggesting little impact of warming-induced lower soil moisture (-15% relative decrease) or a depletion in labile soil C. The fraction of recent plant-derived C in soil respired CO2 from warmed soils was smaller than that from control soils (25 vs. 40% of total C respired), which implies that the warming-induced increase in soil CO2 efflux resulted mainly from mineralization of older SOM rather than from stimulated root respiration. In summary, the 4 ° C soil warming led to C losses from the studied alpine treeline ecosystem by increasing SOM decomposition more than C gains through plant growth.

Wipf, Sonja; Hagedorn, Frank; Martin, Melissa

2010-05-01

208

Effects of ``realistic'' land-cover change on a greenhouse-warmed African climate  

NASA Astrophysics Data System (ADS)

The primary goal of this investigation is to focus on a ``realistic'' scenario for simulating impacts on regional African climate of future deforestation in a greenhouse-warmed world. Combined effects of plausible land-cover change and greenhouse warming are assessed by `time-slice' simulations with an atmospheric general circulation model (AGCM) for the middle of the twenty first century. Three ``time-slice'' integrations have been performed with the ARPEGE-Climat AGCM incorporating a zooming technique to achieve a resolution of about 100 km over Africa. A control run for the current climate is forced by observed climatological sea surface temperatures (SSTs) and the observed vegetation distribution is specified from a new vegetation database, in order to improve the geographical distribution and properties of the vegetation cover. Future SST changes are derived from a transient coupled atmosphere-ocean simulation for scenario B2 of the International Panel on Climate Change (IPCC). Future vegetation changes are specified from a simulation of scenario B2 with the Integrated Model to Assess the Global Environment (IMAGE) developed at the National Institute of Public Health and the Environment in the Netherlands (RIVM). The results show that land surface processes can locally modulate greenhouse warming effects for African climate, with reductions of surface transpiration and small increases of surface temperature. Deforestation of tropical Africa has overall only a marginal effect on precipitation because of a compensatory increase in moisture convergence. Energy budget analyses show that increases in surface temperature are produced both by increases of greenhouse gases (GHG) concentration from the increase in downward atmospheric longwave radiation, and by African tropical deforestation from the resulting reduction in transpiration. This study indicates that realistic land-use changes, though of smaller amplitude than greenhouse gas forcing, may have a small regional effect in projections of future climate.

Maynard, K.; Royer, J.-F.

209

Assessment of the effects of climate warming on Great Lakes basin fishes  

SciTech Connect

The authors combine information on the influence of temperature on the physiology and ecology of fishes with information on the interrelationships between climate and physical limnology for an initial assessment of the impact of future climate warming on fishes and their habitats in the Great Lakes basin. The predicted increase in mean annual air temperature of 3.2-4.8 /sup 0/C is not expected to extirpate fish taxa in the basin. Habitat warming in streams and lakes will likely shrink extant populations of salmonines and coregonines through reductions in preferred thermal habitat and allow range extensions of cyprinids, esocids, centrarchids, and ictalurids. Competition for optimal thermal space within thermal niches will increase, resulting in changes in community composition. Relatively rapid changes in water level would adversely affect the structure of wetlands and littoral areas, reducing their efficacy as spawning and nursery areas. Changes in fisheries yields of preferred species are expected.

Meisner, J.D.; Goodier, J.L.; Regier, H.A.; Shuter, B.J.; Christie, W.J.

1987-01-01

210

Temporal change of climate zones in China in the context of climate warming  

NASA Astrophysics Data System (ADS)

In China, ten climate types were classified using the K-means cluster analysis based on monthly temperature and precipitation data from 753 national meteorological stations for the period 1966-2005. However, 11 mountain climate stations, which are located in southeast China, were classified as one type due to their distinct climate characteristic that differentiated them from other stations. This type could not represent the climate characteristic of this region because all climate stations in this type were located at high-elevation mountains. Thus, it was eliminated when defining climate zones based on climate types. Therefore, nine climate zones were defined in China. Moreover, the temporal change of climate zones was detected in 20-year intervals (1966-1985 and 1986-2005). Although 48 stations changed their climate zones between these two periods, the whole pattern of all climate zones remained stable in these two periods. However, the boundaries between some climate zones changed slightly due to inconsistent variation of regional temperature and precipitation. The most obvious change was the eastern movement of the boundary between an arid temperate zone and a sub-humid temperate zone. There was also a northern shift of the boundary between a tropic zone and a southern subtropic zone. All these changes were probably connected with the climate change in recent 40 years.

Zhang, Xianliang; Yan, Xiaodong

2013-04-01

211

Expansion of global drylands under a warming climate  

NASA Astrophysics Data System (ADS)

Global drylands encompassing hyper-arid, arid, semiarid, and dry subhumid areas cover about 41 percent of the earth's terrestrial surface and are home to more than a third of the world's population. By analyzing observations for 1948-2008 and climate model simulations for 1948-2100, we show that global drylands have expanded in the last sixty years and will continue to expand in the 21st~century. By the end of this century, the world's drylands (under a high greenhouse gas emission scenario) are projected to be 5.8 × 106 km2 (or 10%) larger than in the 1961-1990 climatology. The major expansion of arid regions will occur over southwest North America, the northern fringe of Africa, southern Africa, and Australia, while major expansions of semiarid regions will occur over the north side of the Mediterranean, southern Africa, and North and South America. The global dryland expansions will increase the population affected by water scarcity and land degradations.

Feng, S.; Fu, Q.

2013-10-01

212

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

213

Mechanisms for the land\\/sea warming contrast exhibited by simulations of climate change  

Microsoft Academic Search

The land\\/sea warming contrast is a phenomenon of both equilibrium and transient simulations of climate change: large areas\\u000a of the land surface at most latitudes undergo temperature changes whose amplitude is more than those of the surrounding oceans.\\u000a Using idealised GCM experiments with perturbed SSTs, we show that the land\\/sea contrast in equilibrium simulations is associated\\u000a with local feedbacks and

Manoj M. Joshi; Jonathan M. Gregory; Mark J. Webb; David M. H. Sexton; Tim C. Johns

2008-01-01

214

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

215

Changes in the structural composition and reactivity of Acer rubrum leaf litter tannins exposed to warming and altered precipitation: climatic stress-induced tannins are more reactive.  

PubMed

Climate change could increase the frequency with which plants experience abiotic stresses, leading to changes in their metabolic pathways. These stresses may induce the production of compounds that are structurally and biologically different from constitutive compounds. • We studied how warming and altered precipitation affected the composition, structure, and biological reactivity of leaf litter tannins in Acer rubrum at the Boston-Area Climate Experiment, in Massachusetts, USA. • Warmer and drier climatic conditions led to higher concentrations of protective compounds, including flavonoids and cutin. The abundance and structure of leaf tannins also responded consistently to climatic treatments. Drought and warming in combination doubled the concentration of total tannins, which reached 30% of leaf-litter DW. This treatment also produced condensed tannins with lower polymerization and a greater proportion of procyanidin units, which in turn reduced sequestration of tannins by litter fiber. Furthermore, because of the structural flexibility of these tannins, litter from this treatment exhibited five times more enzyme (?-glucosidase) complexation capacity on a per-weight basis. Warmer and wetter conditions decreased the amount of foliar condensed tannins. • Our finding that warming and drought result in the production of highly reactive tannins is novel, and highly relevant to climate change research as these tannins, by immobilizing microbial enzymes, could slow litter decomposition and thus carbon and nutrient cycling in a warmer, drier world. PMID:21371041

Tharayil, Nishanth; Suseela, Vidya; Triebwasser, Daniella J; Preston, Caroline M; Gerard, Patrick D; Dukes, Jeffrey S

2011-03-04

216

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

217

Increasing Antarctic Sea Ice under Warming Atmospheric and Oceanic Conditions  

Microsoft Academic Search

Estimates of sea ice extent based on satellite observations show an increasing Antarctic sea ice cover from 1979 to 2004 even though in situ observations show a prevailing warming trend in both the atmosphere and the ocean. This riddle is explored here using a global multicategory thickness and enthalpy distribution sea ice model coupled to an ocean model. Forced by

Jinlun Zhang

2007-01-01

218

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

219

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

220

Is it possible to find a solar signature in the current climatic warming?  

NASA Astrophysics Data System (ADS)

This paper investigates whether it is possible to find a solar signature in the current Earth’s climatic warming. The attempt seems audacious as, on one hand, solar output variability on the atmosphere is far to be understood, and on the other hand, there is evidence that most of the warming observed over the last 50 years can be attributed to human activities. However, series of the annual global average temperature, from 1861 up to now are available, showing periods of warming and cooling that are statistically significant. From recent findings, it is also known that solar irradiance shows a variability and can be modeled today with a good accuracy over the last century. The idea was to compare the likelihood linear trends shown in the climatic data with those of the irradiance, during same well defined time ranges. Changes from 1861 to 1975 show an unexpected remarkable correlation, whereas the period 1976 2000 completely deviates from the previous analysis. The 1861 1975 set of data supports the suggestion of an influence of solar irradiance on global climate, which was checked as a natural forcing: the response is found to be ? = 0.46 °C/W m-2, a quite reasonable value, bearing in mind the imprecision in the irradiance modeling. This analysis is also discussed in the scope of other forcings and uncertainties in the data.

Rozelot, J. P.; Lefebvre, S.

221

A global experiment suggests climate warming will not accelerate litter decomposition in streams but might reduce carbon sequestration.  

PubMed

The decomposition of plant litter is one of the most important ecosystem processes in the biosphere and is particularly sensitive to climate warming. Aquatic ecosystems are well suited to studying warming effects on decomposition because the otherwise confounding influence of moisture is constant. By using a latitudinal temperature gradient in an unprecedented global experiment in streams, we found that climate warming will likely hasten microbial litter decomposition and produce an equivalent decline in detritivore-mediated decomposition rates. As a result, overall decomposition rates should remain unchanged. Nevertheless, the process would be profoundly altered, because the shift in importance from detritivores to microbes in warm climates would likely increase CO(2) production and decrease the generation and sequestration of recalcitrant organic particles. In view of recent estimates showing that inland waters are a significant component of the global carbon cycle, this implies consequences for global biogeochemistry and a possible positive climate feedback. PMID:21299824

Boyero, Luz; Pearson, Richard G; Gessner, Mark O; Barmuta, Leon A; Ferreira, Verónica; Graça, Manuel A S; Dudgeon, David; Boulton, Andrew J; Callisto, Marcos; Chauvet, Eric; Helson, Julie E; Bruder, Andreas; Albariño, Ricardo J; Yule, Catherine M; Arunachalam, Muthukumarasamy; Davies, Judy N; Figueroa, Ricardo; Flecker, Alexander S; Ramírez, Alonso; Death, Russell G; Iwata, Tomoya; Mathooko, Jude M; Mathuriau, Catherine; Gonçalves, José F; Moretti, Marcelo S; Jinggut, Tajang; Lamothe, Sylvain; M'Erimba, Charles; Ratnarajah, Lavenia; Schindler, Markus H; Castela, José; Buria, Leonardo M; Cornejo, Aydeé; Villanueva, Verónica D; West, Derek C

2011-02-08

222

Improving golf performance with a warm up conditioning programme  

PubMed Central

Objectives: To determine whether a golf specific warm up programme (both immediately prior to play and after performing it five times a week for 5 weeks) improved performance in 10 male golfers compared with 10 controls matched for age, sex, and handicap. Methods: Twenty male golfers were matched for age (±2 years) and handicap (±1 stroke). Club head speed was assessed by two dimensional video analysis in a laboratory setting. In week 1, all golfers performed 10 strokes. In weeks 2 and 7, the controls underwent the same procedure as in week 1. The exercise group performed the golf specific warm up followed by their 10 strokes. Between weeks 2 and 7, the exercise group performed the specially designed warm up five times a week for 5 weeks. Results: The mean club head speeds of the exercise group improved at each testing week. Between weeks 1 and 2, golfers in the exercise group improved their club head speed on average by 3–6 m/s (12.8%), and between weeks 1 and 7, they increased their club head speeds by 7–10 m/s (24.0%). With the exception of one golfer whose club head speed varied by 1.7 m/s, the mean club head speeds of the golfers in the control group hardly varied over the testing period (range: 0.3–0.8 m/s). A significant difference (p = 0.029) was found between the mean club head speeds of the exercise and control groups over the duration of the study, and a significant interaction over time (p<0.001) was also found. Conclusions: This study has shown that golfers' performances will be significantly improved by undertaking a golf specific warm up programme compared with not performing the warm up.

Fradkin, A; Sherman, C; Finch, C

2004-01-01

223

Simulation of the Tropical Pacific Warm Pool with the NCAR Climate System Model*.  

NASA Astrophysics Data System (ADS)

The simulation of the tropical western Pacific warm pool is explored with the NCAR Climate System Model (CSM). The simulated sea surface temperatures in the Pacific basin have biases that are similar to other coupled model simulations in this region. In particular, an excessive cold tongue of water extends across the Pacific basin, with warm water on either side of this cold tongue. The warm pool region is also too cold. This cold bias exists in spite of an overestimate in surface net energy flux into this region. To understand the source of this bias in SST, simulations from the uncoupled and fully coupled models are analyzed in terms of biases in surface energy budget. These analyses suggest that the strong constraint of little ocean heat transport out of the warm pool region forces a change in SST gradient that leads to an increase in the atmospheric zonal wind. This increase in zonal wind causes an increase in latent heat flux in the warm pool region. The increase in latent heat flux is required to offset a significant (35 W m2) bias in net surface solar flux. The bias in surface solar flux is due to an underestimate of model cloud shortwave absorption.

Kiehl, J. T.

1998-06-01

224

A sensitivity study to global desertification in cold and warm climates: results from the IPSL OAGCM model  

Microsoft Academic Search

Many simulations have been devoted to study the impact of global desertification on climate, but very few have quantified\\u000a this impact in very different climate contexts. Here, the climatic impacts of large-scale global desertification in warm (2100\\u000a under the SRES A2 scenario forcing), modern and cold (Last Glacial Maximum, 21 thousand years ago) climates are assessed by\\u000a using the IPSL

Ramdane Alkama; Masa Kageyama; Gilles Ramstein

2011-01-01

225

Assessing the strength of regional changes in near-surface climate associated with a global warming of 2°C  

Microsoft Academic Search

In this study, the strength of the regional changes in near-surface climate associated with a global warming of 2°C with respect\\u000a to pre-industrial times is assessed, distinguishing between 26 different regions. Also, the strength of these regional climate\\u000a changes is compared to the strength of the respective changes associated with a markedly stronger global warming of 4.5°C.\\u000a The magnitude of

Wilhelm May

2010-01-01

226

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

227

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

228

Correlation between recruitment and fall condition of age-0 pollock (Theragra chalcogramma) from the eastern Bering Sea under varying climate conditions  

NASA Astrophysics Data System (ADS)

Fishery managers require an understanding of how climate influences recruitment if they are to separate the effects of fishing and climate on production. The southeastern Bering Sea offers opportunities to understand climate effects on recruitment because inter-annual oscillations in ice coverage set up warm or cold conditions for juvenile fish production. Depth-averaged temperature anomalies in the Bering Sea indicate the past nine years have included three warm (2003-2005), an average (2006), and five cold (2007-2011) years. We examined how these climatic states influenced the diet quality and condition (size, energy density and total energy) of young-of-the-year (YOY) pollock (Theragra chalcogramma) in fall. The implications of fall condition were further examined by relating condition prior to winter to the number of age-1 recruits-per-spawner the following summer (R/S). The percentage of lipid in pollock diets was threefold higher in cold years compared with warm years, but stomach fullness did not vary. Consequently, fish energy densities were 33% higher in cold years (P<0.001) than in warm years. In contrast, neither fish size (P=0.666), nor total energy (P=0.197) varied with climatic condition. However, total energy was significantly (P=0.007) and positively correlated with R/S (R2=0.736). We conclude that recruitment to age-1 in the southeastern Bering Sea is improved under environmental conditions that produce large, energy dense YOY pollock in fall.

Heintz, Ron A.; Siddon, Elizabeth C.; Farley, Edward V.; Napp, Jeffrey M.

2013-10-01

229

Detrimental effects of recent ocean surface warming on growth condition of Atlantic salmon  

Microsoft Academic Search

Ocean climate impacts on survivorship and growth of Atlantic salmon are complex, but still poorly understood. Stock abundances have declined over the past three decades and 1992-2006 has seen widespread sea surface temperature (SST) warming of the NE Atlantic, including the foraging areas exploited by salmon of southern European origin. Salmon cease feeding on return migration, and here we express

CHRISTOPHER D. T ODD; S ARAH L. H UGHES; M AC LEAN; E. L ONERGAN

2008-01-01

230

Detrimental effects of recent ocean surface warming on growth condition of Atlantic salmon  

Microsoft Academic Search

Ocean climate impacts on survivorship and growth of Atlantic salmon are complex, but still poorly understood. Stock abundances have declined over the past three decades and 1992-2006 has seen widespread sea surface temperature (SST) warming of the NE Atlantic, including the foraging areas exploited by salmon of southern European origin. Salmon cease feeding on return migration, and here we express

CHRISTOPHER D. T ODD; S ARAH L. H UGHES; C. T A R A M A R S H A L Lz

231

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.

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

232

Warming and wetting signals emerging from analysis of changes in climate extreme indices over South America  

NASA Astrophysics Data System (ADS)

Here we show and discuss the results of an assessment of changes in both area-averaged and station-based climate extreme indices over South America (SA) for the 1950-2010 and 1969-2009 periods using high-quality daily maximum and minimum temperature and precipitation series. A weeklong regional workshop in Guayaquil (Ecuador) provided the opportunity to extend the current picture of changes in climate extreme indices over SA.Our results provide evidence of warming and wetting across the whole SA since the mid-20th century onwards. Nighttime (minimum) temperature indices show the largest rates of warming (e.g. for tropical nights, cold and warm nights), while daytime (maximum) temperature indices also point to warming (e.g. for cold days, summer days, the annual lowest daytime temperature), but at lower rates than for minimums. Both tails of night-time temperatures have warmed by a similar magnitude, with cold days (the annual lowest nighttime and daytime temperatures) seeing reductions (increases). Trends are strong and moderate (moderate to weak) for regional-averaged (local) indices, most of them pointing to a less cold SA during the day and warmer night-time temperatures.Regionally-averaged precipitation indices show clear wetting and a signature of intensified heavy rain events over the eastern part of the continent. The annual amounts of rainfall are rising strongly over south-east SA (26.41 mm/decade) and Amazonia (16.09 mm/decade), but north-east Brazil and the western part of SA have experienced non-significant decreases. Very wet and extremely days, the annual maximum 5-day and 1-day precipitation show the largest upward trends, indicating an intensified rainfall signal for SA, particularly over Amazonia and south-east SA. Local trends for precipitation extreme indices are in general less coherent spatially, but with more general spatially coherent upward trends in extremely wet days over all SA.

Skansi, María de los Milagros; Brunet, Manola; Sigró, Javier; Aguilar, Enric; Arevalo Groening, Juan Andrés; Bentancur, Oscar J.; Castellón Geier, Yaruska Rosa; Correa Amaya, Ruth Leonor; Jácome, Homero; Malheiros Ramos, Andrea; Oria Rojas, Clara; Pasten, Alejandro Max; Sallons Mitro, Sukarni; Villaroel Jiménez, Claudia; Martínez, Rodney; Alexander, Lisa V.; Jones, P. D.

2013-01-01

233

Runoff sensitivities of major global river basins in a warming climate  

NASA Astrophysics Data System (ADS)

Runoff is a key index of renewable water resources which affect almost all human and natural systems. Any substantial change in runoff therefore has the potential to impact food and freshwater security. We analyze the runoff response to global warming as predicted by climate change experiments generated for the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. In contrast to previous work, we estimate the sensitivity of runoff per degree of global mean temperature change, with the rationale that the global average temperature change is indexed to cumulative global emissions, and therefore removes most of the dependence on emissions scenarios. Our results show that the predicted fractional change in runoff per degree warming is relatively stable across emissions scenarios and global mean temperature increments, but varies substantially across models with the exception of the high-latitudes and currently arid or semi-arid areas. Among the 194 large global river basins studied, the number of basins with decreasing runoff increases by about 12% per degree global temperature increase, and the associated fraction of global land area, effected population, and effected Gross Domestic Product (GDP) increases by about 6, 5, and 8%, respectively. The areas, where the projected runoff decreases more than 10% of the runoff in the period of 1970-1999, cover 13% of the global land area and 20% of the global GDP at a 2 degree C global warming, suggesting substantial expansion of drought area in a warming climate. The estimated runoff elasticity to precipitation ranges from about one to three. The predicted runoff decreases between 2 to 6% per degree local temperature increase over most basins in North America and the middle and high latitudes of Eurasia.

Tang, Q.; Lettenmaier, D. P.

2011-12-01

234

Changing habitat associations of a thermally constrained species, the silver-spotted skipper butterfly, in response to climate warming.  

PubMed

1. The impact of climate change on the distribution, abundance, phenology and ecophysiology of species is already well documented, whereas the influence of climate change on habitat choice and utilization has received little attention. Here we report the changing habitat associations of a thermally constrained grassland butterfly, Hesperia comma, over 20 years. 2. Between 1982 and 2001-2, the optimum percentage of bare ground within habitat used for egg-laying shifted from 41% to 21%. 3. Egg-laying rates are temperature-dependent and females actively adjust microhabitat usage in response to temperature variations; relatively warmer host plants are chosen or oviposition at low ambient temperatures, and cooler host plants at high ambient temperatures. 4. Climate warming has increased the availability of thermally suitable habitat for H. comma at the cool, northern edge of the species' distribution, therefore increasing: (a) egg-laying rate and potentially the realized rate of population increase; (b) effective area of habitat patches as more microhabitats within a given vegetation fragment are now suitable for egg-laying; (c) buffering of populations against environmental variation as eggs are laid within a wider range of microhabitats; and (d) the number of habitat patches in the landscape that are currently available for colonization (including the use of more northerly facing aspects; Thomas et al., Nature, 2001, 411, 577-581). 5. Conservationists often assume the habitat requirements of a species to be constant, and manage habitats to maintain these conditions. For many species, these requirements are likely to change in response to climate warming, and care must be taken not to manage habitats based on outdated prescriptions. PMID:16903062

Davies, Zoe G; Wilson, Robert J; Coles, Sophie; Thomas, Chris D

2006-01-01

235

Estimating thermal regimes of bull trout and assessing the potential effects of climate warming on critical habitats  

USGS Publications Warehouse

Understanding the vulnerability of aquatic species and habitats under climate change is critical for conservation and management of freshwater systems. Climate warming is predicted to increase water temperatures in freshwater ecosystems worldwide, yet few studies have developed spatially explicit modelling tools for understanding the potential impacts. We parameterized a nonspatial model, a spatial flow-routed model, and a spatial hierarchical model to predict August stream temperatures (22-m resolution) throughout the Flathead River Basin, USA and Canada. Model comparisons showed that the spatial models performed significantly better than the nonspatial model, explaining the spatial autocorrelation found between sites. The spatial hierarchical model explained 82% of the variation in summer mean (August) stream temperatures and was used to estimate thermal regimes for threatened bull trout (Salvelinus confluentus) habitats, one of the most thermally sensitive coldwater species in western North America. The model estimated summer thermal regimes of spawning and rearing habitats at <13 C° and foraging, migrating, and overwintering habitats at <14 C°. To illustrate the useful application of such a model, we simulated climate warming scenarios to quantify potential loss of critical habitats under forecasted climatic conditions. As air and water temperatures continue to increase, our model simulations show that lower portions of the Flathead River Basin drainage (foraging, migrating, and overwintering habitat) may become thermally unsuitable and headwater streams (spawning and rearing) may become isolated because of increasing thermal fragmentation during summer. Model results can be used to focus conservation and management efforts on populations of concern, by identifying critical habitats and assessing thermal changes at a local scale.

Jones, Leslie A.; Muhlfeld, Clint C.; Marshall, Lucy A.; McGlynn, Brian L.; Kershner, Jeffrey L.

2013-01-01

236

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

237

Influence of climate variability on whitefish (Coregonus lavaretus) year-class strength in a deep, warm monomictic lake.  

PubMed

The year-class strength (YCS) of Blaufelchen (Coregonus lavaretus) in deep Upper Lake Constance was analysed for a 52-year period, from 1947 to 1998. Despite strong anthropogenic influences on the species' population dynamics due to cultural eutrophication and oligotrophication, intense fishing, and large-scale stocking, the influence of climate variability associated with the North Atlantic Oscillation (NAO) is apparent in the data set. This influence is significant although large-scale stocking of cold-bred larvae was performed to avoid a mismatch of larvae with their food. The importance of stocking on YCS, however, is unclear and was only detectable when analysing a subset of the data. In addition to climate variability a yet unidentified factor related to zooplankton suitability as food for fish larvae, and density-dependent mortality probably related to cannibalism do significantly influence YCS. The NAO seemed to influence YCS twofold, through temperature effects on egg development time and on larval growth rate. The first of these two mechanisms is related to the NAO via a time lag of 1 year due to the specific mixing dynamics of warm monomictic Lake Constance. Hence, a warm winter in the year before spawning results in earlier hatching of larvae, that is, hatching is decoupled from the actual meteorological conditions. This should make the larvae very prone to mismatch the dynamics of their food. However, we found no evidence for such a mismatch in this 52-year data set. PMID:17109176

Straile, Dietmar; Eckmann, Reiner; Jüngling, Tobias; Thomas, Gregor; Löffler, Herbert

2006-11-16

238

Climatic warming and basal melting of large ice sheets: possible implications for East Antarctica  

SciTech Connect

Climatic warming is shown to be capable of inducing shear heating instability and basal melting in a model ice sheet that is creeping slowly downslope. Growth times of the instability are calculated from a nonlinear analysis of temperature and flow in the model ice sheet whose surface undergoes a prescribed increase of temperature. The source of instability lies in the decrease of maximum ice thickness for steady downslope creep with increasing surface temperature. A surface temperature increase of 5 to 10 k can cause instability on a 10/sup 4/ year time scale for realistic ice rheology. The instability occurs suddenly after a prolonged period of dormancy. The instability might be relevant to the East Antarctic ice sheet. Warming associated with the Holocene interglacial epoch that heralded the end of the last ice age may have set the East Antarctic ice sheet on a course toward wide-spread instability some 10/sup 4/ years later. The present CO/sub 2/-induced climate warming is also a potential trigger for instability and basal melting of the East Antarctic ice sheet.

Saari, M.R.; Yuen, D.A.; Schubert, G.

1987-01-01

239

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

240

The Political Economy of Climate Change Mitigation Policies: How to Build a Constituency to Address Global Warming?  

Microsoft Academic Search

Developments over the past few years have shown that reforms to address climate change are no less difficult to implement than reforms in other areas, even if the objective of limiting global warming is broadly accepted. In the case of global public goods such as the climate, the political challenge is further complicated by the need to convince voters that

Alain de Serres; John Llewellyn; Preston Llewellyn

2011-01-01

241

Using the LANDIS model to evaluate forest harvesting and planting strategies under possible warming climates in Northeastern China  

Microsoft Academic Search

The Small Khingan Mountains in northeastern China provide most of the timber and wood products in the country. Evaluating the long-term effects of harvesting and planting strategies is important especially as the climate changes. In this study, we evaluated the effects of the projected climate warming on potential changes in species’ coverage (percent cover), area harvested (percentage of the study

Rencang Bu; Hong S. He; Yuanman Hu; Yu Chang; David. R. Larsen

2008-01-01

242

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

243

The toxicology of climate change: environmental contaminants in a warming world.  

PubMed

Climate change induced by anthropogenic warming of the earth's atmosphere is a daunting problem. This review examines one of the consequences of climate change that has only recently attracted attention: namely, the effects of climate change on the environmental distribution and toxicity of chemical pollutants. A review was undertaken of the scientific literature (original research articles, reviews, government and intergovernmental reports) focusing on the interactions of toxicants with the environmental parameters, temperature, precipitation, and salinity, as altered by climate change. Three broad classes of chemical toxicants of global significance were the focus: air pollutants, persistent organic pollutants (POPs), including some organochlorine pesticides, and other classes of pesticides. Generally, increases in temperature will enhance the toxicity of contaminants and increase concentrations of tropospheric ozone regionally, but will also likely increase rates of chemical degradation. While further research is needed, climate change coupled with air pollutant exposures may have potentially serious adverse consequences for human health in urban and polluted regions. Climate change producing alterations in: food webs, lipid dynamics, ice and snow melt, and organic carbon cycling could result in increased POP levels in water, soil, and biota. There is also compelling evidence that increasing temperatures could be deleterious to pollutant-exposed wildlife. For example, elevated water temperatures may alter the biotransformation of contaminants to more bioactive metabolites and impair homeostasis. The complex interactions between climate change and pollutants may be particularly problematic for species living at the edge of their physiological tolerance range where acclimation capacity may be limited. In addition to temperature increases, regional precipitation patterns are projected to be altered with climate change. Regions subject to decreases in precipitation may experience enhanced volatilization of POPs and pesticides to the atmosphere. Reduced precipitation will also increase air pollution in urbanized regions resulting in negative health effects, which may be exacerbated by temperature increases. Regions subject to increased precipitation will have lower levels of air pollution, but will likely experience enhanced surface deposition of airborne POPs and increased run-off of pesticides. Moreover, increases in the intensity and frequency of storm events linked to climate change could lead to more severe episodes of chemical contamination of water bodies and surrounding watersheds. Changes in salinity may affect aquatic organisms as an independent stressor as well as by altering the bioavailability and in some instances increasing the toxicity of chemicals. A paramount issue will be to identify species and populations especially vulnerable to climate-pollutant interactions, in the context of the many other physical, chemical, and biological stressors that will be altered with climate change. Moreover, it will be important to predict tipping points that might trigger or accelerate synergistic interactions between climate change and contaminant exposures. PMID:19375165

Noyes, Pamela D; McElwee, Matthew K; Miller, Hilary D; Clark, Bryan W; Van Tiem, Lindsey A; Walcott, Kia C; Erwin, Kyle N; Levin, Edward D

2009-04-16

244

Elevation and connectivity define genetic refugia for mountain sheep as climate warms.  

PubMed

Global warming is predicted to affect the evolutionary potential of natural populations. We assessed genetic diversity of 25 populations of desert bighorn sheep (Ovis canadensis nelsoni) in southeastern California, where temperatures have increased and precipitation has decreased during the 20th century. Populations in low-elevation habitats had lower genetic diversity, presumably reflecting more fluctuations in population sizes and founder effects. Higher-elevation habitats acted as reservoirs of genetic diversity. However, genetic diversity was also affected by population connectivity, which has been disrupted by human development. Restoring population connectivity may be necessary to buffer the effects of climate change on this desert-adapted ungulate. PMID:17107466

Epps, Clinton W; Palsbøll, Per J; Wehausen, John D; Roderick, George K; McCullough, Dale R

2006-12-01

245

Response of global warming on regional climate change over Korea: An experiment with the MM5 model  

NASA Astrophysics Data System (ADS)

This study is to investigate changes in regional surface climate arising from global warming with MM5 downscaling simulation for the period 1971-2100. The main focus is on the drought conditions over Korea. Palmer Drought Severity Index (PDSI) is utilized as a measure of drought severity. The important findings show the increase of surface air temperature by 6°C and precipitation by 25% over Korea at the end of the 21st century. The increasing trend of temperature is associated with an increasing trend of evapotranspiration and precipitation. Climatological precipitation amount appropriate for existing conditions is larger than the precipitation amounts. Hence, it actually produces deficit in precipitation. This exhibits a negative PDSI. As a result droughts are expected to be severe and frequent. Better resolved topography in MM5 induces large changes in local precipitation compared with temperature. Consequently peaks of negative PDSI anomalies appear over southern parts of Korea, where a large reduction in precipitation is noticed in addition to warming.

Boo, Kyung-On; Kwon, Won-Tae; Oh, Jai-Ho; Baek, Hee-Jeong

2004-11-01

246

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

Microsoft Academic Search

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 Niño–like conditions with impacts similar to those of the 1997\\/1998 El Niño event. Here we use a general circulation model to examine the global-scale effects that result from imposing warm tropical sea surface

Sonali P. Shukla; Mark A. Chandler; Jeff Jonas; Linda E. Sohl; Ken Mankoff; Harry Dowsett

2009-01-01

247

Global Farm Animal Production and Global Warming: Impacting and Mitigating Climate Change  

PubMed Central

Background The farm animal sector is the single largest anthropogenic user of land, contributing to many environmental problems, including global warming and climate change. Objectives The aim of this study was to synthesize and expand upon existing data on the contribution of farm animal production to climate change. Methods We analyzed the scientific literature on farm animal production and documented greenhouse gas (GHG) emissions, as well as various mitigation strategies. Discussions An analysis of meat, egg, and milk production encompasses not only the direct rearing and slaughtering of animals, but also grain and fertilizer production for animal feed, waste storage and disposal, water use, and energy expenditures on farms and in transporting feed and finished animal products, among other key impacts of the production process as a whole. Conclusions Immediate and far-reaching changes in current animal agriculture practices and consumption patterns are both critical and timely if GHGs from the farm animal sector are to be mitigated.

Koneswaran, Gowri; Nierenberg, Danielle

2008-01-01

248

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

249

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

250

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

NASA Astrophysics Data System (ADS)

Glacial terminations are characterized by a strong rise in sea level related to melting ice sheets. This rise in sea level is not uniform all over the world, because regional effects (uplift and subsidence of coastal zones) are superimposed on global trends. For the Laptev Sea, Bauch et al. (2001) have shown that during the early Holocene the shelf area became flooded from 8.9 ka BP (-31 m) to 7.5 ka BP (-7 m, close to modern day coastline). An extrapolation of this result on the basis of modern bathymetry suggests that a far bigger area, covering the entire East Siberian Sea, became flooded at that time. This area is currently known as a sea-ice production zone (Tamura and Ohshima, 2010) and contributes significantly to the sea-ice exported from the Arctic through the Fram Strait (~20% of annual sea-ice area passing Fram Strait, Rigor and Colony, 1997). This leads to the following hypothesis: during times of lower sea levels, the coastline advances closer to the shelf break and reduces the amount of sea-ice production on these shelves, reducing sea-ice volume and export through Fram Strait and causing the sea-ice extent to retreat in the Nordic Seas, yielding warmer and saltier sea surface conditions. We have tested this hypothesis in a ocean-sea-ice-atmosphere coupled model of intermediate complexity (LOVECLIM), thereby focusing on an early Holocene (9 ka BP) test case. We use the results of 9 snapshot simulations with different model configurations, differing in land-sea-mask, manually prescribed ice sheets and melt fluxes from the Laurentide Ice sheet and the Greenland Ice sheet. Simulations with an unflooded East Siberian shelf show lower sea-ice production, a retreat of the sea-ice extent in the Nordic Seas and an increase in temperature and salinity on the northern East Greenland Current. Together with the retreating sea ice cover, local deep convection shifts from south of the Denmark Strait up to 9 degrees north, following the sea ice edge and resulting in heat release and surface warming during the entire year. Our analysis exhibits a surprising connection between increased sea-ice export through Fram Strait and changes in atmospheric winds that result from modifications in the atmospheric circulation, that are forced by changes in differential heating over the East Siberian Shelf and the Nordic Seas. This atmospheric teleconnection clearly shows that regional changes can affect hemispheric changes. In a first comparison with available sea-ice proxy reconstructions our results do not disagree, but show the necessity of increased temporal and spatial coverage of proxy reconstructions for future investigations. Our results indicate that shelf flooding had a significant impact on the climate during the early Holocene, namely reducing sea-ice cover and affecting atmospheric circulation. During terminations this can be considered to be a negative feedback on the progress of the termination, as a shelf area becomes flooded, sea-ice production and extent are likely to increase and reduce high latitude intake of orbitally-forced insolation, slowing down the warming trend. This can be the cause of observed cold reversals during warming phases in the continuous transformation of a glacial to an interglacial climate. This implies that shelf flooding should be taken into account when studying the climate dynamics during all glacial terminations. References Bauch, H.; Mueller-Lupp, T.; Taldenkova, E.; Spielhagen, R.; Kassens, H.; Grootes, P.; Thiede, J.; Heinemeier, J. & Petryashov, V. Chronology of the Holocene transgression at the North Siberian margin, Global and Planetary Change, 2001, 31, 125 - 139 Rigor, I. & Colony, R., Sea-ice production and transport of pollutants in the Laptev Sea, 1979-1993, Science of The Total Environment, Environmental Radioactivity in the Arctic, 1997, 202, 89-110 Tamura, T. & Ohshima, K. I., Mapping of sea ice production in the Arctic coastal polynyas, J. Geophys. Res., AGU, 2011, 116, C07030-

Blaschek, Michael; Renssen, Hans

2013-04-01

251

Warming the nursing education climate for traditional-age learners who are male.  

PubMed

For nurse educators to facilitate student learning and the achievement of desired cognitive, affective, and psychomotor outcomes, they need to be competent in recognizing the influence of gender, experience, and other factors on teaching and learning. A study was conducted in one academic institution to describe how traditional-age male learners' perceptions of the nursing education climate compare to perceptions of female learners. Interviews were conducted with a sample of four male and four female learners. Additional data from interviews with nurse educators, classroom observations, and a review of textbooks provided breadth and depth to their perceptions. Findings support a nursing education climate that is cooler to traditional-age male learners and warmer to traditional-age female learners. The main cooling factor for men was caused by nurse educators' characteristics and unsupportive behaviors. Additional factors inside and outside the education environment contributed to a cooler climate for the male learners. Based on these findings, strategies for nurse educators to warm the education climate for traditional-age male learners are presented. PMID:18575237

Bell-Scriber, Marietta J

252

Methane bubbling from Siberian thaw lakes as a positive feedback to climate warming.  

PubMed

Large uncertainties in the budget of atmospheric methane, an important greenhouse gas, limit the accuracy of climate change projections. Thaw lakes in North Siberia are known to emit methane, but the magnitude of these emissions remains uncertain because most methane is released through ebullition (bubbling), which is spatially and temporally variable. Here we report a new method of measuring ebullition and use it to quantify methane emissions from two thaw lakes in North Siberia. We show that ebullition accounts for 95 per cent of methane emissions from these lakes, and that methane flux from thaw lakes in our study region may be five times higher than previously estimated. Extrapolation of these fluxes indicates that thaw lakes in North Siberia emit 3.8 teragrams of methane per year, which increases present estimates of methane emissions from northern wetlands (< 6-40 teragrams per year; refs 1, 2, 4-6) by between 10 and 63 per cent. We find that thawing permafrost along lake margins accounts for most of the methane released from the lakes, and estimate that an expansion of thaw lakes between 1974 and 2000, which was concurrent with regional warming, increased methane emissions in our study region by 58 per cent. Furthermore, the Pleistocene age (35,260-42,900 years) of methane emitted from hotspots along thawing lake margins indicates that this positive feedback to climate warming has led to the release of old carbon stocks previously stored in permafrost. PMID:16957728

Walter, K M; Zimov, S A; Chanton, J P; Verbyla, D; Chapin, F S

2006-09-01

253

Biogeochemical plant-soil microbe feedback in response to climate warming in peatlands  

NASA Astrophysics Data System (ADS)

Peatlands act as global sinks of atmospheric carbon (C) through the accumulation of organic matter, primarily made up of decay-resistant litter of peat mosses. However, climate warming has been shown to promote vascular plant growth in peatlands, especially ericaceous shrubs. A change in vegetation cover is in turn expected to modify above-ground/below-ground interactions, but the biogeochemical mechanisms involved remain unknown. Here, by selecting peatlands at different altitudes to simulate a natural gradient of soil temperature, we show that the expansion of ericaceous shrubs with warming is associated with an increase of polyphenol content in both plant litter and pore water. In turn, this retards the release of nitrogen (N) from decomposing litter, increases the amount of dissolved organic N and reduces N immobilization by soil microbes. A decrease of soil water content with increasing temperature promotes the growth of fungi, which feeds back positively on ericaceous shrubs by facilitating the symbiotic acquisition of dissolved organic N. We also observed a higher release of labile C from vascular plant roots at higher soil temperatures, which promotes the microbial investment in C-degrading enzymes. Our data suggest that climate-induced changes in plant cover can reduce the productivity of peat mosses and potentially prime the decomposition of organic matter by affecting the stoichiometry of soil enzymatic activity.

Bragazza, Luca; Parisod, Julien; Buttler, Alexandre; Bardgett, Richard D.

2013-03-01

254

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

255

Decreased frequency of North Atlantic polar lows associated with future climate warming.  

PubMed

Every winter, the high-latitude oceans are struck by severe storms that are considerably smaller than the weather-dominating synoptic depressions. Accompanied by strong winds and heavy precipitation, these often explosively developing mesoscale cyclones-termed polar lows-constitute a threat to offshore activities such as shipping or oil and gas exploitation. Yet owing to their small scale, polar lows are poorly represented in the observational and global reanalysis data often used for climatological investigations of atmospheric features and cannot be assessed in coarse-resolution global simulations of possible future climates. Here we show that in a future anthropogenically warmed climate, the frequency of polar lows is projected to decline. We used a series of regional climate model simulations to downscale a set of global climate change scenarios from the Intergovernmental Panel of Climate Change. In this process, we first simulated the formation of polar low systems in the North Atlantic and then counted the individual cases. A previous study using NCEP/NCAR re-analysis data revealed that polar low frequency from 1948 to 2005 did not systematically change. Now, in projections for the end of the twenty-first century, we found a significantly lower number of polar lows and a northward shift of their mean genesis region in response to elevated atmospheric greenhouse gas concentration. This change can be related to changes in the North Atlantic sea surface temperature and mid-troposphere temperature; the latter is found to rise faster than the former so that the resulting stability is increased, hindering the formation or intensification of polar lows. Our results provide a rare example of a climate change effect in which a type of extreme weather is likely to decrease, rather than increase. PMID:20844533

Zahn, Matthias; von Storch, Hans

2010-09-16

256

Nitrogen partitioning in oak leaves depends on species, provenance, climate conditions and soil type.  

PubMed

Climate-tolerant tree species and/or provenances have to be selected to ensure the high productivity of managed forests in Central Europe under the prognosticated climate changes. For this purpose, we studied the responses of saplings from three oak species (i.e. Quercus robur, Q. petraea and Q. pubescens) and provenances of different climatic origin (i.e. low or high rainfall, low or high temperature habitats) with regard to leaf nitrogen (N) composition as a measure of N nutrition. Saplings were grown in model ecosystems on either calcareous or acidic soil and subjected to one of four treatments (control, drought, air warming or a combination of drought and air warming). Across species, oak N metabolism responded to the influence of drought and/or air warming with an increase in leaf amino acid N concentration at the expense of structural N. Moreover, provenances or species from drier habitats were more tolerant to the climate conditions applied, as indicated by an increase in amino acid N (comparing species) or soluble protein N (comparing provenances within a species). Furthermore, amino acid N concentrations of oak leaves were significantly higher on calcareous compared to acidic soil. From these results, it can be concluded that seeds from provenances or species originating from drier habitats and - if available - from calcareous soil types may provide a superior seed source for future forest establishment. PMID:22934888

Hu, B; Simon, J; Kuster, T M; Arend, M; Siegwolf, R; Rennenberg, H

2012-08-31

257

Evidence for external forcing on 20th-century climate from combined ocean-atmosphere warming patterns  

NASA Astrophysics Data System (ADS)

Of the additional energy absorbed by the Earth over the past decades, by far the largest fraction is taken up by the oceans. Yet most attribution studies focus on the surface warming, and only few have used patterns of ocean warming to attribute changes to external forcing or internal variability. Here we use the combined observed evidence from warming of the atmosphere and ocean with the latest climate model simulations to demonstrate that both the depth profiles and spatial warming patterns near the surface are very heterogeneous when resulting from internal unforced variability. In the 20th-century simulations on the other hand, the observed spatial pattern is smooth, and the warming decreases almost gradually with depth in the ocean, consistent with observations and a penetration of the surface warming to intermediate depth by diffusion and advection. We argue that such physically motivated arguments combining different lines of evidence and types of observations offer insight that is complementary to optimal fingerprint attribution methods. We conclude that the simultaneous global warming of the atmosphere and mixed layer alone is uninformative for attribution, but the magnitude of ocean heat uptake, the homogeneity of the spatial pattern as well as the distribution of warming below the mixed layer strongly argue for the 20th-century warming being largely externally forced.

Sedlá?ek, Jan; Knutti, Reto

2012-10-01

258

Climate-Years in the True Prairie: Temporal Fluctuations of Ecologically Critical Climate Conditions  

Microsoft Academic Search

The True Prairie (TP) is a large area in the central U.S. which was a tall grass prairie for thousands of years prior to its conversion to crop land. An analysis of climatically controlling factors indicated that the tall grass prairie is favored by the ratio of warm season precipitation to potential evapotranspiration exceeding 0.75 (west boundary), cold season precipitation

Kenneth E. Kunkel

2003-01-01

259

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

260

Characterization of the Unregulated Spring Snowmelt Recession in the Sierra Nevada, California, and Potential Changes with Regional Climate Warming  

NASA Astrophysics Data System (ADS)

In previous work, we developed a conceptual model for the ecology and management of the spring snowmelt recession in Mediterranean-montane catchments. This conceptual model focused on three components of the Natural Flow Regime: magnitude, timing, and rate of change. Here we provide a model definition and develop synthetic hydrographs of the spring snowmelt recession for unregulated catchments of the Sierra Nevada, California. By modeling the exponential decay of snowmelt pulses, we show the scalability of the spring snowmelt recession limb slope at multiple temporal scales and explore empirical evidence for stationarity found in unregulated rivers in contrast with regulated river systems. Lastly, we show the results of spring snowmelt recession dynamics for climate altered hydrologies simulated in the WEAP21 rainfall-runoff model for the entire western Sierra Nevada. Our results show that with regional climate warming the present rate of change in the snowmelt recession will significantly decrease due to substantial reductions in snowpack and increased duration of low flow conditions. These results suggest potential impacts to freshwater and riparian organisms, which currently respond to the spring snowmelt period and accompanying flow conditions as a favorable window of opportunity for reproduction and population expansion.

Viers, J. H.; Epke, G.; Yarnell, S.; Mount, J. F.

2009-12-01

261

Variability in Eastern North American surface ozone under climate warming scenarios: Key role for jet position  

NASA Astrophysics Data System (ADS)

Climate warming is generally expected to degrade air quality in many polluted regions. Model estimates of the magnitude, and in some cases the sign, of the surface ozone response to projected warming, however, disagree regionally. These discrepancies underscore a need for improved process-level understanding of the factors controlling the regional ozone response to warming. Furthermore, developing accurate approaches to estimate regional surface ozone changes directly from projected changes in regional climate requires this process understanding. Over Eastern North America, synoptic variability is known to be a key driver of summertime ozone pollution episodes. We investigate the hypothesis that this variability depends on the position of the jet within this region by analyzing June-August (JJA) daily surface ozone in a suite of CMIP5 and related sensitivity simulations from 1860 to 2100 in the GFDL CM3 chemistry-climate model. Specifically, we use the CM3 CMIP5 Historical (1860-2005; 5-member) and RCP4.5 (2006-2100; 3-member) ensemble simulations. An additional scenario with evolving well-mixed greenhouse gases following the RCP4.5 scenario but emissions of aerosol and ozone precursors held constant at 2005 levels, denoted RCP4.5*, enables us to isolate the impact of climate warming alone from the impact of large decreases in ozone precursor emissions occurring under RCP4.5. We demonstrate that the daily variability of JJA surface ozone is a strong function of the position of the jet-stream over Eastern North America in all three scenarios. The jet stream moves poleward with climate change under the RCP4.5 and RCP4.5* scenarios, and we show that ozone variability follows the position of the jet. The consistent response in both the RCP4.5 and RCP4.5* simulations demonstrates that the large decreases in ozone precursor emissions under RCP4.5 (North American nitrogen oxides (NOx) decrease by about a factor of 5 over the 21st century) are not driving the northward shift of ozone variability. While the relationship with jet latitude remains, the decrease in ozone precursor emissions under RCP4.5 leads to a reduction in variability over the entire region. We further show that the strength of the correlation between ozone and temperature is a strong function of the jet position. The quantitative relationship (slope between ozone and temperature), however, depends strongly on NOx emissions, consistent with recent observation-based work. These findings demonstrate that historical relationships between surface ozone and meteorological quantities such as temperature are unlikely to apply in the future. Although this study focuses solely on Eastern North America, the relationships found here are likely also present in other mid-latitude regions influenced by the mid-latitude jet. The strong dependence of surface ozone variability on jet latitude, a quantity easily computed from climate models, implies that understanding future changes in jet location can be used to derive changes in summertime surface ozone variability and the ozone-temperature correlation. Our results further imply that inter-model discrepancies in jet location likely contribute to the wide range of current estimates for changes in surface ozone in northern mid-latitude regions.

Barnes, Elizabeth; Fiore, Arlene

2013-04-01

262

Climatic conditions and migration: An econometric inquiry  

Microsoft Academic Search

Among a burgeoning literature dealing with the economic and noneconomic determinants of migration, one area that has received relatively little attention is the relationship between climate and migration. In the few studies which include climate variables in models used to explain migration, the treatment accorded to climate as an explanatory variable has not been satisfactory. This paper attempts to fill

Stephen M. Renas; Rishi Kumar

1983-01-01

263

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

2010-08-13

264

Simulated Fish Habitat Changes in North American Lakes in Response to Projected Climate Warming  

Microsoft Academic Search

Abstract.—Fish habitat is strongly constrained,by water temperature,and the available dissolved oxygen,(DO). Fish habitat in small lakes of the contiguous,United States was therefore determined from simulated,daily water temperature,and dissolved oxygen,profiles. Twenty-seven,types of lakes were simulated,under past (1962?1979) climate conditions and a projected doubling,of atmospheric carbon,dioxide,(23CO, climate scenario) at 209 locations in the contiguous,United States. The 23CO2 climate scenario,was,derived from,the output of

Heinz G. Stefan; Xing Fang; John G. Eaton

2001-01-01

265

Simulated Fish Habitat Changes in North American Lakes in Response to Projected Climate Warming  

Microsoft Academic Search

Fish habitat is strongly constrained by water temperature and the available dissolved oxygen (DO). Fish habitat in small lakes of the contiguous United States was therefore determined from simulated daily water temperature and dissolved oxygen profiles. Twenty-seven types of lakes were simulated under past (1962–1979) climate conditions and a projected doubling of atmospheric carbon dioxide (2×CO2 climate scenario) at 209

Heinz G. Stefan; Xing Fang; John G. Eaton

2001-01-01

266

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

267

A Mechanism for Land-Ocean Contrasts in Global Monsoon Trends in a Warming Climate  

NASA Astrophysics Data System (ADS)

A central paradox of the modern global monsoon record involves reported decreases in rainfall over land in an environment in which the global hydrologic cycle is both expected and observed to intensify. Perhaps equally confounding are projections of annual mean tropical convection, which exhibits disproportionate strengthening over ocean. This work develops a physical basis for understanding both the observed record of the global monsoon and its anticipated changes in a warming climate. In doing so it bolsters the concept of a global monsoon in the context of common feedbacks. The global monsoon record across multiple reanalyses is first assessed. Identifiably spurious trends are identified in all reanalysis products and these are linked to changes in their assimilated data streams, both prior to and during the satellite era. The confidence in reported trends in the global monsoon based on reanalyses is thus deemed to be low. Simulated trends in the global monsoon from the CMIP3 archive are then assessed and their land-ocean contrasts are found to agree qualitatively with recent studies using satellite retrievals of rainfall. A feedback mechanism is proposed to explain the contrast that is rooted in the facts that 1) land areas warm disproportionately relative to ocean in a warming climate, and 2) that onshore flow is the chief source of monsoonal moisture. The inextricable consequence of these facts is that, for a fixed mass flow, the increase in oceanic moisture advection is constrained by the rise saturated humidity over ocean. Over land, as a consequence of greater warming, the increase in saturated humidity will be considerably greater. Reductions in lower tropospheric relative humidity (RH) over land monsoon domains associated with this mechanism are therefore inevitable. Reduced RH has direct consequences for convection including a raising of the lifting condensation level and a shift in the distribution of convection generally towards less frequent and potentially more intense events. Cloud amount and the frequency of rainfall are thus expected to decrease, though the total rainfall may increase arising from increases in specific humidity and convective instability. Competition with neighboring ocean regions, where increases in CAPE are disproportionately large relative to land, further augments the contrast. Manifestations of the mechanism are demonstrated to be robust across the CMIP3 archive and thus their existence is not owed to an individual model's treatment of convection or clouds. The mechanism is interpreted as an important modulating influence on the "rich-get-richer" mechanism advanced by previous works. Regional contrasts in the mechanism are discussed.

Fasullo, J.

2011-12-01

268

Aerosol contribution to the rapid warming of near-term climate under RCP 2.6  

NASA Astrophysics Data System (ADS)

The importance of aerosol emissions for near term climate projections is investigated by analysing simulations with the HadGEM2-ES model under two different emissions scenarios: RCP2.6 and RCP4.5. It is shown that the near term warming projected under RCP2.6 is greater than under RCP4.5, even though the greenhouse gas forcing is lower. Rapid and substantial reductions in sulphate aerosol emissions due to a reduction of coal burning in RCP2.6 lead to a reduction in the negative shortwave forcing due to aerosol direct and indirect effects. Indirect effects play an important role over the northern hemisphere oceans, especially the subtropical northeastern Pacific where an anomaly of 5-10 Wm-2 develops. The pattern of surface temperature change is consistent with the expected response to this surface radiation anomaly, whilst also exhibiting features that reflect redistribution of energy, and feedbacks, within the climate system. These results demonstrate the importance of aerosol emissions as a key source of uncertainty in near term projections of global and regional climate.

Chalmers, N.; Highwood, E. J.; Hawkins, E.; Sutton, R.; Wilcox, L. J.

2012-09-01

269

Forest Dynamics and Their Phenological Response to Climate Warming in the Khingan Mountains, Northeastern China  

PubMed Central

The Khingan Mountain region, the most important and typical natural foci of tick-borne encephalitis (TBE) in China, is the largest and northernmost forest area and the one more sensitive to climate change. Taking this region as the study area, we investigated the spatio-temporal dynamics of deciduous broadleaf forest (DBF) and its phenology changes in relation to climate change and elevation. Based on MODIS Enhanced Vegetation Index (EVI) time series over the period of 2001 to 2009, the start-of-season (SOS), length-of-season (LOS) and another two vegetation variables (seasonal amplitude (SA) and integrated EVI (SI)) were derived. Over the past decade, the DBF in Khingan Mountains has generally degraded and over 65% of DBF has experienced negative SA and SI trends. Earlier trends in SOS and longer trends in LOS for DBF were observed, and these trends were mainly caused by climate warming. In addition, results from our analysis also indicated that the effects of temperature on DBF phenology were elevation dependent. The magnitude of advancement in SOS and extension in LOS with temperature increase significantly increased along a raising elevation gradient.

Cai, Hongyan; Zhang, Shuwen; Yang, Xiaohuan

2012-01-01

270

Warm to cold polar climate transitions over the last 15,000 years: A paleoclimatology record from the raised beaches of northern Norway  

SciTech Connect

Because of the strength of the cold, dry arctic high pressure vortex, and the absence of multiple air-mass sources, climate records from the polar region tend to display a cleaner signal than those from mid-latitude settings. The high arctic presents unique opportunities for the prediction of the natural background pattern of climate change prior to the disturbances generated by manmade atmospheric pollutants. The Varanger Peninsula of northernmost Norway was extensively depressed by an ice dome during the last glacial stage. Deglaciation was accompanied by isostatic recovery at a steady though exponentially decaying rate. Superimposed on the rising land is a discontinuous staircase of cobble beach ridges, deposited during the postglacial period by storms at the coast. The ridges are constructed during brief episodes of weather- and tide-related elevation of sea level and wave run-up. Storminess periods can only occur in the absence of sea ice associated with several decades of mild, relatively warm temperatures. A history of local relative sea level is constructed from over 70 radiocarbon dates of various water-level indicators. The sea-level history is used to construct a chronology of beach-ridge building that documents the cyclic, a periodic nature of arctic storminess conditions. The authors date a dynamic signal with multiple climate transitions from warm, stormy conditions to cool, calm conditions occurring roughly every 200 years between 15,000 years ago to 10,000 years ago. Throughout the Holocene the climate is more settled with longer periods separating the major warm to cool transitions.

Fletcher, C.H. (Univ. of Hawaii, Honolulu (United States)); Fairbridge, R.H. (NASA-Goddard Inst. for Space Studies, New York, NY (United States)); Moeller, J.K. (Univ. of Tromso (Norway)); Long, A.J. (Univ. of Durham (United Kingdom))

1991-03-01

271

Response of hurricane-type vortices to global warming as simulated by ARPEGE-Climat at high resolution  

Microsoft Academic Search

Atlantic hurricanes and their sensitivity to anthropogenic warming are investigated using very high (0.5°×0.5° over the Atlantic domain) resolution global simulations. The ARPEGE-Climat variable resolution grid demonstrates its usefulness in regional climate studies since resolution can be multiplied by a factor of 2.5 over the domain of interest compared to a uniform grid, for a similar computer cost. The question

Fabrice Chauvin; Jean-François Royer; Michel Déqué

2006-01-01

272

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

Microsoft Academic Search

In this study, a zonally-averaged statistical climate model (SDM) is used to investigate the impact of global warming on the\\u000a distribution of the geobotanic zones over the globe. The model includes a parameterization of the biogeophysical feedback\\u000a mechanism that links the state of surface to the atmosphere (a bidirectional interaction between vegetation and climate).\\u000a In the control experiment (simulation of

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

273

Potential impact of climate warming on the distribution of the Golden-striped salamander, Chioglossa lusitanica , on the Iberian Peninsula  

Microsoft Academic Search

The increase in the concentration of greenhouse gases in the atmosphere is expected to impact the world's climate on a time-scale of just decades. We simulated the potential impact of climate warming on the range of the Iberian endemic Golden-striped salamander, Chioglossa lusitanica, by extrapolating present-day GIS-based distribution models. The results indicated a significant decrease in the distribution of the

J. Teixeira; J. W. Arntzen

2002-01-01

274

Potential impact of climate warming on the distribution of the Golden-striped salamander, Chioglossa lusitanica, on the Iberian Peninsula  

Microsoft Academic Search

The increase in the concentration of greenhouse gases in the atmosphere is expected to impact the world's climate on a time-scale of just decades. We simulated the potential impact of climate warming on the range of the Iberian endemic Golden-striped salamander, Chioglossa lusitanica, by extrapolating present-day GIS-based distribution models. The results indicated a significant decrease in the distribu- tion of

J. TEIXEIRA; J. W. ARNTZEN

2002-01-01

275

Can warm climate-related structure of littoral predator assemblies weaken the clear water state in shallow lakes?  

Microsoft Academic Search

Shallow lakes, the most abundant lake type in the world, are very sensitive to climatic changes. The structure and functioning of shallow lakes are greatly impacted by sub- merged plants, and these may be affected by climate warming in various, contrasting, ways. Following a space-for-time substitution approach, we aimed to analyse the role of aquatic (submerged and free-floating) plants in

J UAN; CARLOS I GLESIAS; R. P EDERSEN; Ole Worms

2007-01-01

276

Response of River Runoff in the Cryolithic Zone of Eastern Siberia (Lena River Basin) to Future Climate Warming  

Microsoft Academic Search

\\u000a During the last several decades significant climate warming has been observed in the permafrost regions of Eastern Siberia.\\u000a Observed environmental changes include increasing air temperature and to a lesser degree precipitation. Changes in regional\\u000a climate are accompanied by changes in river runoff. Seasonal and long-term changes of river runoff in different parts of the\\u000a Lena river basin are characterized by

A. G. Georgiadi; I. P. Milyukova; E. A. Kashutina

277

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.

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

2013-01-01

278

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

279

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

280

Climate warming and changes in habitat suitability for Boophilus microplus (Acari: Ixodidae) in Central America.  

PubMed

Remote sensing on the basis of AVHRR (advanced very high resolution radiometer) satellite imagery was used, together with standard geostatistical methods (cokriging), to estimate the distribution of habitat suitability (HS) for the tick Boophilus microplus (Canestrini) in Central America. Most attention was paid to the expected limits of tick distribution as well as the temperature and vegetation values responsible for different HS zones and their variability within the year. The highest HS extended through wide areas of southeastern United States, much of Mexico, and other countries of Central America. Areas with higher HS had relatively stable temperatures (within 20-25 C) throughout the year, and had a NDVI (normalized derived vegetation index) of around 0.4. These areas need to be targeted to ensure acaricide usage at optimum intervals and to avoid the formation of areas with enzootic instability. A seasonal analysis of the climate trend through the study period (1982-1999) revealed a warming cycle, together with a rise in NDVI index values. The main consequence of this trend is the gradual increase in unsuitability in areas where the tick is already established, with the establishment of new foci in zones currently too cold to support tick populations. The cooling periods of 1-2 yr that were observed between warming cycles may also lead to enzootic instability when warm zones cool to within the suitability range. As the model is remotely sensed, a continuous update of the B. microplus distribution could be performed, assuring maximum efficiency in developing management strategies. PMID:11695419

Estrada-Peña, A

2001-10-01

281

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.

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, Rene; Ohman, Marcus C.; Garpe, Kajsa C.; Edwards, Alasdair J.; Sheppard, Charles R. C.

2008-01-01

282

Soil organic carbon projections in Mediterranean soils under climate change conditions  

NASA Astrophysics Data System (ADS)

Soil organic carbon (SOC) plays a vital role in ecosystem function determining soil fertility, water holding capacity and susceptibility to land degradation. In addition, SOC is related to atmospheric CO2 levels with soils having the potential for C release or sequestration, depending on land use, land management, and climate. The Mediterranean region is expected to be highly affected by climate change, and it is expected that SOC decreases under climate warming conditions. Estimates of soil organic carbon stocks and changes under different climate scenarios and land use systems can also help to determine the vulnerability to land degradation. In this work an assessment of changes in soil organic carbon for Sardinia, the second largest island of the Mediterranean Basin, is presented. The carbon dynamics were estimated for the whole island using the Rothamsted Carbon model and the A1b emission scenario provided by the Euro-Mediterranean Centre for Climate Change (CMCC). Almost 200 soil analysis data were used to calibrate and validate the model output for different land use typologies. After the calibration, a good agreement between soil C estimated from the model with the current climate and observed SOC data was found. Preliminary results show a general reduction in the soil C content with the A1b scenario projection (-18% in the 2100 vs 2000). The SOC reduction in the soils was higher in the forested and semi-natural ecosystems than agricultural areas. In addition, an increase of 4.3% in the CO2 fluxes is expected at the end of the 21th century. The work allowed an estimation of the SOC projections for the current century under climate warming conditions, identifying the potential contribution of the several land use typologies. The methodological approach constitutes a first exercise where other processes, such as changes in land use, and in the net primary production need to be accounted for a more comprehensive approach in the SOC dynamics estimations and projections for the future.

Sirca, C.; Carta, M.; Salis, M.; Spano, D.

2012-04-01

283

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

284

Mid?latitude (30°–60° N) climatic warming inferred by combining borehole temperatures with surface air temperatures  

Microsoft Academic Search

We construct a mid-latitude (30 ? -60 ? N) re- duced temperature-depth profile from a global borehole tem- perature database compiled for climate reconstruction. This reduced temperature profile isinterpreted in termsof pas t surface ground temperature change and indicates warming on the order of 1 ? C over the past 100 to 200 years. The combination of an initial temperature

Robert N. Harris; David S. Chapman

2001-01-01

285

Stomatal response to air humidity and its relation to stomatal density in a wide range of warm climate species  

Microsoft Academic Search

The gas exchange of 19 widely different warm climate species was observed at different leaf to air vapour pressure deficits (VPD). In all species stomata tended to close as VPD increased resulting in a decrease in net photosynthesis. The absolute reduction in leaf conductance per unit increase in VPD was greatest in those species which had a large leaf conductance

Mabrouk A. El-Sharkawy; James H. Cock; Ana Hernandez

1985-01-01

286

Rapid Carbon Accumulation Associated With Warm Medieval Climate in Peatlands of a Glaciated Valley in Southcentral Alaska  

NASA Astrophysics Data System (ADS)

Peatlands are among the largest reservoirs of terrestrial carbon (C) in the northern hemisphere. Understanding how this carbon pool will respond to climate changes is critical to assessing potential earth-system feedbacks. Peatland C accumulation is controlled by the relative rates of production and decomposition, and the rate of these processes is affected by many factors, including temperature, hydrology, and vegetation. In order to better understand the potential influences of past climate change on C accumulation, we developed a coupled study of peatland paleohydrology and C accumulation from a Sphagnum-dominated peatland located in a glaciated valley south of the Alaska Range in southcentral Alaska. Past responses of this peatland to well-documented climate and temperature changes, like the Medieval Climate Anomaly (MCA) at 1000-600 cal yr BP and Little Ice Age (LIA) at 600-100 cal yr BP, were investigated using water-table depths inferred from testate amoebae and C accumulation rates calculated from loss-on-ignition and 14C-dating analyses. Although warmer temperatures, like those experienced in Alaska during the MCA, might be expected to result in lower water tables and reduced C accumulation, our results indicate that the peatland C accumulation rate during the MCA (~150 gC/m2/yr) was about three times greater than during the LIA (~50 gC/m2/yr). Also, reconstructed water-table depths indicate relatively wet conditions on the peatland during the MCA, suggesting that this region may have experienced increased precipitation during this time, or increased melting of glaciers. Although glacier meltwater was not hydrologically connected to the peatland, it may have led to greater relative humidity that mediated potential drying associated with warmer temperatures. We found that the average ash-free bulk density values during the MCA (0.128 g/cm3) were lower than the average values during the LIA (0.172 g/cm3), consistent with our reconstructed water-table depths. Furthermore, our data show that C accumulation rates during the post-LIA recent warming have been similar to those experienced during the MCA. This study implies that some northern peatlands could serve as a negative feedback to climate change by sequestering more C as temperatures increase, given sufficient moisture conditions are maintained through increased precipitation or by other hydrological changes, such as those from receding glaciers.

Klein, E. S.; Booth, R. K.; Yu, Z.

2010-12-01

287

Vegetation limits the impact of a warm climate on boreal wildfires.  

PubMed

Strategic introduction of less flammable broadleaf vegetation into landscapes was suggested as a management strategy for decreasing the risk of boreal wildfires projected under climatic change. However, the realization and strength of this offsetting effect in an actual environment remain to be demonstrated. Here we combined paleoecological data, global climate models and wildfire modelling to assess regional fire frequency (RegFF, i.e. the number of fires through time) in boreal forests as it relates to tree species composition and climate over millennial time-scales. Lacustrine charcoals from northern landscapes of eastern boreal Canada indicate that RegFF during the mid-Holocene (6000-3000 yr ago) was significantly higher than pre-industrial RegFF (AD c. 1750). In southern landscapes, RegFF was not significantly higher than the pre-industrial RegFF in spite of the declining drought severity. The modelling experiment indicates that the high fire risk brought about by a warmer and drier climate in the south during the mid-Holocene was offset by a higher broadleaf component. Our data highlight an important function for broadleaf vegetation in determining boreal RegFF in a warmer climate. We estimate that its feedback may be large enough to offset the projected climate change impacts on drought conditions. PMID:23691916

Girardin, Martin P; Ali, Adam A; Carcaillet, Christopher; Blarquez, Olivier; Hély, Christelle; Terrier, Aurélie; Genries, Aurélie; Bergeron, Yves

2013-05-21

288

A sensitivity study to global desertification in cold and warm climates: results from the IPSL OAGCM model  

NASA Astrophysics Data System (ADS)

Many simulations have been devoted to study the impact of global desertification on climate, but very few have quantified this impact in very different climate contexts. Here, the climatic impacts of large-scale global desertification in warm (2100 under the SRES A2 scenario forcing), modern and cold (Last Glacial Maximum, 21 thousand years ago) climates are assessed by using the IPSL OAGCM. For each climate, two simulations have been performed, one in which the continents are covered by modern vegetation, the other in which global vegetation is changed to desert i.e. bare soil. The comparison between desert and present vegetation worlds reveals that the prevailing signal in terms of surface energy budget is dominated by the reduction of upward latent heat transfer. Replacing the vegetation by bare soil has similar impacts on surface air temperature South of 20°N in all three climatic contexts, with a warming over tropical forests and a slight cooling over semi-arid and arid areas, and these temperature changes are of the same order of magnitude. North of 20°N, the difference between the temperatures simulated with present day vegetation and in a desert world is mainly due to the change in net radiation related to the modulation of the snow albedo by vegetation, which is obviously absent in the desert world simulations. The enhanced albedo in the desert world simulations induces a large temperature decrease, especially during summer in the cold and modern climatic contexts, whereas the largest difference occurs during winter in the warm climate. This temperature difference requires a larger heat transport to the northern high latitudes. Part of this heat transport increase is achieved through an intensification of the Atlantic Meridional Overturning Circulation. This intensification reduces the sea-ice extent and causes a warming over the North Atlantic and Arctic oceans in the warm climate context. In contrast, the large cooling North of 20°N in both the modern and cold climate contexts induces an increase in sea-ice extent.

Alkama, Ramdane; Kageyama, Masa; Ramstein, Gilles

2012-04-01

289

Increasing Mississippi Discharge During Both the Little Ice Age and Medieval Warm Period: A Gulf of Mexico Perspective on Climate Variability Over North America  

NASA Astrophysics Data System (ADS)

Late Holocene climate variability includes the Little Ice Age (LIA, 1550-1850 AD) and the Medieval Warm Period (MWP, 800-1200 AD) that are characterized by contrasting hydrologic and thermal regimes. This climatic paradigm of a dry/cold LIA and a wet/warm MWP is documented at the local and regional scale through the interpretation of tree ring, speleothem and lake records. In contrast, marine sedimentary records from basins proximal to major rivers integrate climate signals across large spatial scales and can provide a coherent, high-resolution assessment of the oceanic and continental responses to changing climate and hydrologic conditions. The Pigmy Basin in the northern Gulf of Mexico is ideally situated to record inputs from the Mississippi River and to relate these inputs to changing hydrologic conditions over North America during the LIA and MWP. Using molecular organic and inorganic geochemical analyses from a dated sediment core, we document increasing terrestrial plant and lithogenic inputs during both the LIA and the MWP suggesting wet conditions over North America characterized both cold and warm climate regimes. Wet conditions for the LIA and MWP are inferred from 4-fold and 5-fold increases, respectively, in the contribution of terrestrially derived long-chain n-alkanes, and concurrent increases in the percent insoluble residues of the bulk sediments. Associated solely with the wet intervals, algal derived n-alkanes increases by 5-fold and 3-fold during the LIA and MWP, respectively, suggesting that continent-derived nutrients supported marine production. Surprisingly, the ratio of algal:terrestrial organic matter inputs is greater in the LIA than the MWP suggesting that nutrient delivery mechanisms are facilitated preferentially during the wet/cold interval. Geochemical trends in the Pigmy Basin show coherence with the Cariaco Basin Ti record indicating a climatic tele-connection between the low latitude tropics and sub-tropical to temperate region of North America. The climatological significance of LIA and MWP wet events will be discussed in terms of modern meteorological conditions and the long-term changes in solar forcing and seasonal dominance over North America.

Flannery, J. A.; Hill, H. W.; Poore, R. Z.; Hollander, D. J.

2005-12-01

290

European warming linked to Greenland melting during the Last Interglacial North Atlantic climate optimum  

NASA Astrophysics Data System (ADS)

Recent models and data synthesis suggest that the Last Interglacial North Atlantic warm optimum, ~130 ±2 ka, corresponded with a sea level stand of 4-9 m higher than that of the present-day implying that a substantial part of the Greenland Ice Sheet (GIS) melted at that time. This makes this interglacial a good analogue for understanding the impact of the ongoing global warming and GIS melting on the Atlantic Meridional Overturning Circulation (AMOC) and adjacent landmasses. Here we provide new insights on the impact of insolation and AMOC changes on western European ecosystems and climate and their regional transmission during an episode of GIS melting that can be considered somehow similar to that predicted for 2100 C.E. from IPCC projections. We have revisited three pollen-rich western European margin sequences distributed from 37 to 45°N, MD04-2845, MD95-2042 and MD99-2331, which span all of MIS 5 and are directly affected by the descending branch of the North Atlantic Drift. The analysis of these sequences allows us to directly correlate marine tracers of AMOC variability and changes in ice volume, sea surface temperature (SST), iceberg discharges and pollen-derived European vegetation and climate. The comparison of these observations with those inferred from other locations in the North Atlantic region directly affected by the AMOC and records from the Eirik Drift off southern Greenland document the response of North Atlantic climate to GIS melting during the Last Interglacial. Large and rapid increase in the Western European forest cover and mid-latitude North Atlantic SST at the beginning of MIS 5e benthic isotopic plateau following the YD-like event coincide with strong GIS melting. Despite continued GIS melting during this interval, AMOC strength gradually increases. The dramatic expansion of western European forest could be the result of both AMOC and insolation increase. Subsequently sustained warm SSTs and strong AMOC do not preclude the long term forest reduction which parallels insolation decrease. On millennial time scales, repeated decreases in GIS runoff occurred when Europe and the adjacent ocean cooled and AMOC strength weakened. Contrary to what would be expected if GIS melting triggering reduced AMOC with attendant forest reductions and cooling in western Europe and the North Atlantic Ocean, our study suggests that GIS melting increases at the same time as the subpolar and mid latitudes of the North Atlantic and adjacent landmasses experienced warming with AMOC reinvigoration. Given the potential analogue between the Last Interglacial and the end of this century, we suggest that in contrast to GIS melting weakening AMOC, increased radiative forcing leading to future GIS melting may be associated with increased AMOC strengthwarming of Western Europe and a larger extent of temperate forests, in the absence of human intervention.

Sanchez Goni, M.; Michel, E.; Desprat, S.; Carlson, A. E.; Naughton, F.; Fletcher, W. J.; Rossignol, L.

2010-12-01

291

Shifts in biogenic carbon flow from particulate to dissolved forms under high carbon dioxide and warm ocean conditions  

NASA Astrophysics Data System (ADS)

Photosynthesis by phytoplankton in sunlit surface waters transforms inorganic carbon and nutrients into organic matter, a portion of which is subsequently transported vertically through the water column by the process known as the biological carbon pump (BCP). The BCP sustains the steep vertical gradient in total dissolved carbon, thereby contributing to net carbon sequestration. Any changes in the vertical transportation of the organic matter as a result of future climate variations will directly affect surface ocean carbon dioxide (CO2) concentrations, and subsequently influence oceanic uptake of atmospheric CO2 and climate. Here we present results of experiments designed to investigate the potential effects of ocean acidification and warming on the BCP. These perturbation experiments were carried out in enclosures (3,000 L volume) in a controlled mesocosm facility that mimicked future pCO2 (˜900 ppmv) and temperature (3°C higher than ambient) conditions. The elevated CO2 and temperature treatments disproportionately enhanced the ratio of dissolved organic carbon (DOC) production to particulate organic carbon (POC) production, whereas the total organic carbon (TOC) production remained relatively constant under all conditions tested. A greater partitioning of organic carbon into the DOC pool indicated a shift in the organic carbon flow from the particulate to dissolved forms, which may affect the major pathways involved in organic carbon export and sequestration under future ocean conditions.

Kim, Ja-Myung; Lee, Kitack; Shin, Kyungsoon; Yang, Eun Jin; Engel, Anja; Karl, David M.; Kim, Hyun-Cheol

2011-04-01

292

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

293

Potential impacts of a warming climate on water availability in snow-dominated regions.  

PubMed

All currently available climate models predict a near-surface warming trend under the influence of rising levels of greenhouse gases in the atmosphere. In addition to the direct effects on climate--for example, on the frequency of heatwaves--this increase in surface temperatures has important consequences for the hydrological cycle, particularly in regions where water supply is currently dominated by melting snow or ice. In a warmer world, less winter precipitation falls as snow and the melting of winter snow occurs earlier in spring. Even without any changes in precipitation intensity, both of these effects lead to a shift in peak river runoff to winter and early spring, away from summer and autumn when demand is highest. Where storage capacities are not sufficient, much of the winter runoff will immediately be lost to the oceans. With more than one-sixth of the Earth's population relying on glaciers and seasonal snow packs for their water supply, the consequences of these hydrological changes for future water availability--predicted with high confidence and already diagnosed in some regions--are likely to be severe. PMID:16292301

Barnett, T P; Adam, J C; Lettenmaier, D P

2005-11-17

294

Response of Lena basin river runoff to recent and projected global climate warming  

NASA Astrophysics Data System (ADS)

It follows from the results of calculations fulfilled that in the period of intensive warming of regional climate (beginning with the 1980s) the average annual air temperature rose very considerably, but heterogeneously over the territory of the Lena River basin. The most significant rise is observed in central, eastern and southern parts of the basin. The character of change of annual precipitation is going on in this period less homogeneously over the basin's territory. Over the past 20 years the phase of increase of annual and seasonal river runoff is observed on the main tributaries of the Lena River. Comparison of intraannual changes of river runoff in Lena river basin for the examined periods (before 1980-th and beginning with 1981) shows that: 1) in downstream of Lena river the most noticeable increase of river runoff occurs in cold part of year while in parts of basin upper confluences of Aldan river and Vilyui river changes river runoff intraanual distribution are more homogeneous and are less significant; 2) the most noticeable increase of the Lena River runoff in cold part of the year is observed below of the confluence of the Aldan River and Vilyui river; 3) considerable increase of river runoff in low part of Vilyui river in many respects can be connected to its artificial regulation as result of dam construction; 4) in downstream gages of right-bank tributaries of upstream and middle stream of Lena river (Vitim, Olekma) changes of intraannual river runoff distribution are less noticeable and are more homogeneously distributed within year. According to the results of hydrological modeling the expected anthropogenic climate warming in XXI century can bring more significant river runoff increase in the Lena river basin as compared with the recent one. Hydrological responses to climate warming have been evaluated for the plain part of the Lena river basin basing on a macroscale hydrological model featuring simplified description of processes developed in Institute of Geography of the Russian Academy of Sciences. Two atmosphere-ocean global circulation models included in the IPCC (ECHAM4/OPY3 and GFDL-R30) were used as scenarios of future global climate. The both scenarios suggest quite a significant change in the character of the annual stream-flow distribution in middle of XXI. The scenarios give, in essence, the similar pattern of changes in the wave of spring-summer high water. The onset of the flood can be shifted one month backward, as compared with the current situation. The main contribution to the river runoff change in the mid-21st century can be made by the increase in atmospheric precipitation and air temperature, while the scenario changes in the active layer depth are not to make a perceptible impact.

Georgiadi, Alexander; Milyukova, Irina; Kashutina, Ekaterina

2010-05-01

295

Total environmental warming impact (TEWI) calculations for alternative automative air-conditioning systems  

Microsoft Academic Search

The Montreal Protocol phase-out of chlorofluorocarbons (CFCs) has required manufacturers to develop refrigeration and air-conditioning systems that use refrigerants that can not damage stratospheric ozone. Most refrigeration industries have adapted their designs to use hydrochlorofluorocarbon (HCFC) or hydrofluorocarbon (HFC) refrigerants; new automobile air- conditioning systems use HFC-134a. These industries are now being affected by scientific investigations of greenhouse warming and

J. R. Sand; S. K. Fischer

1997-01-01

296

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

297

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

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

298

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.

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

2010-01-01

299

Sequential chilling-forcing models predict budburst phenology best in deciduous trees: results from a climate warming experiment  

NASA Astrophysics Data System (ADS)

Modeling budburst phenology is important for assessing the impact of climate change on ecosystem processes. Based on historical datasets, the simple growing degree days models were thought to successfully reproduce budburst date. However, many tree species require a certain amount of winter chilling and the future warming may result in insufficient chilling. Therefore, modeling future phenology shifts needs evaluation of the budburst process based on warming experiments. In this study, we conducted a 2-year warming experiment, with different warming levels. The main aims of this study were to assess the budburst response to winter and spring warming and to estimate the accuracy of five budburst models. One-meter-high saplings of three deciduous tree species were used, i.e. birch (Betula pendula L.), oak (Quercus robur L.) and beech (Fagus sylvatica L.). The results showed that the manipulated warming results in a wide range of budburst dates across the three studied species. Both warming winter and spring substantially advanced the timing of budburst. Model evaluation shows that both one-(without chilling) and two-(with chilling) phase models are able to accurately predict the observation date. The best performing model differed among the three species. The growing degree days model performed best for oak and birch. The model with sequential chilling and forcing yielded similar good results for these two species, but was by far the best model for beech. Therefore, a model with a sequential budburst pattern may be more appropriate to simulate budburst data in a future warmer climate in which chilling progressively becomes more limiting.

Fu, Y. S. H.; Campioli, M.; Deckmyn, G.; Janssens, I. A.

2012-04-01

300

Pronounced climate warming during early Middle Pleistocene interglacials: investigating the mid-Brunhes event in the British terrestrial sequence  

NASA Astrophysics Data System (ADS)

The mid-Brunhes event is a climatic transition that occurs between MIS 13 and 11 (ca 450,000 yrs B.P.) and is primarily characterised by an increase in the amount of warming received by interglacial episodes over the last 450,000 yrs relative to that experienced during interglacials of the early Middle Pleistocene (780,000 - 450,000 yrs B.P.). This event is observable within a range of long climate records (e.g. SPECMAP, EPICA etc) but its effect on terrestrial systems is poorly understood. The impact of this event in northwest Europe is tested through the British terrestrial sequence by the comparison of multi-proxy climate reconstructions for interglacials of the early Middle Pleistocene with climate reconstructions from the late Middle and Late Pleistocene (<500,000 B.P.). This comparison reveals that interglacial climates during the early Middle Pleistocene in Britain were, in fact, as warm as, and in some cases warmer than, those that occurred during the late Middle and Late Pleistocene. This suggestion is supported by sea surface temperature records in the North Atlantic which show that temperatures during the early Middle Pleistocene interglacials were at least as warm as the Holocene. There is therefore no evidence, in climate records of northwest Europe and the North Atlantic, for a mid-Brunhes event. This suggests that the mid-Brunhes event is not a global climatic transition but only impacts certain regions of the world, however, further work is needed to understand the extent of this significant transition and the reason for this regional variation.

Candy, I.; Rose, J.; Silva, B.; Lee, J.

2009-04-01

301

Reef fish dynamic response to climatic variability in a warm eastern Mediterranean semi-enclosed basin  

NASA Astrophysics Data System (ADS)

Recent studies on the effects of global warming on fish populations reveal that the resulting hypoxia-based habitat compression due to the expansion of the oxygen minimum zone may lead to the restriction of fish depth distributions to the oxygenated near-surface layer1. Here we postulate that similar phenomena may have affected the fish distribution in the early Pliocene Heraklion semi-enclosed sea (Crete, eastern Mediterranean). Fish otoliths from Voutes section are systematically identified and the data is examined from a palaeoecologic perspective in response to the Pliocene climatic variability. Bregmaceros and Diaphus taaningi otoliths' relative abundances are used as reliable palaeoclimatic indicators2. The Voutes section sediments contain a very rich fish fauna. Diaphus spp., Bregmaceros sp., Sardinella maderensis, Phosichthyidae and Sternoptychyidae form the pelagic component. Mesopelagic taxa belong mostly to Myctophids. The benthopelagic and benthic component of the fish fauna is very well diversified and is comprised of Gobiids, such as Gobius cf. niger, Callogobius sp., Lesueurigobius aff. sanzoi, and Aphya sp., as well as Gadiculus labiatus, Laemonema sp., Oblada melanura, Parascombrus mutinensis, Barbourisia rufa, Blennius sp., Ammodytes sp., Solea aff. solea. The presence of Oligopus sp., Spratelloides sp., and Brotula cf. mutlibarbata in the middle part of the section indicate the development of a reef in the study area. The palaeoecologic analysis of the surface, intermediate and deep water faunal groups indicate that the pelagic fish populations in the semi-enclosed early Pliocene Heraklion basin directly reflect the climatic variability. However, the intermediate and deep water fish did not respond to climate change in the same manner. Indeed, two dysoxic events are recorded in this section, where the pelagic component of the fauna is almost exclusively comprised of Bregmaceros sp., few Myctophids are present, and the benthic and benthopelagic taxa are nearly non-existent. These events are intermitted by the development of a reef system near the study area, marked by the intense diversification of the fish fauna on all water levels. The mollusc fauna turnover reinforces the above results. Conclusively, the present study clearly presents the fish populations' dynamic characteristics of in response to climatic variability. Acknowledgments This research has been co-financed by the European Union (European Social Fund - ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) - Research Funding Program: Heracleitus II. Investing in knowledge society through the European Social Fund.

Agiadi, K.; Koskeridou, E.; Giamali, Ch.; Karakitsios, V.

2012-04-01

302

Barrier layers of the Atlantic warm pool: Formation mechanism and influence on weather and climate  

NASA Astrophysics Data System (ADS)

The aim of this research is to study the formation mechanism of Barrier Layers (BL) in the western tropical Atlantic and their influence on the tropical Atlantic climate at both short and long timescales. Many Coupled General Circulation Models (CGCMs) tend to overestimate the salinity in the Atlantic warm pool or the Northwestern Tropical Atlantic (NWTA) and underestimate the surface salinity in the subtropical salinity maxima region. Most of these models also suffer from a sea-surface temperature (SST) bias in the NWTA region, leading to suggestions that the upper ocean salinity stratification may need to be improved in order to improve the BL simulations and thus the SST through BL-SST-Intertropical Convergence Zone (ITCZ) feedbacks. We used a CGCM to perform a set of idealized numerical experiments to understand the sensitivity of the BL and consequently SST in the NWTA region to freshwater flux and hence the upper ocean salinity stratification. We find that the BL of the western tropical Atlantic is quite sensitive to upper ocean salinity changes in the Amazon River discharge region and the subtropical salinity maxima region. The BL phenomenon is further manifested by the formation of winter temperature inversions in our model simulations. However, in the region of improved BL simulation, the SST response is not statistically significant. SST response to Tropical Cyclones (TCs) is studied for the Atlantic region using a high-resolution coupled regional climate model (CRCM) and observational data sets. The presence of a BL, defined as the layer below the mixed layer that separates the base of the isothermal layer from the base of the isohaline layer, is found to modulate the SST response. The amplitude of TC-induced surface cooling is reduced by more than 35% in the presence of a BL, as a consequence of the weak thermal stratification. Furthermore, in locations when the BL exhibits a temperature inversion, TC-induced mixing can result in weak surface warming. BLs considerably reduce the rightward bias for tropical storms, but the effect is less conspicuous for TCs. The enthalpy flux into the atmosphere at the air-sea interface is enhanced by 16 % and the increase in upper ocean potential energy due to TC-induced mixing is reduced by 25 % in the presence of BLs. The results from the coupled model are supported by an observational analysis performed using re-analysis data sets, as well as data from Argo floats and TRMM satellite. As previous modeling and observational studies have indicated that the surface cooling caused by TC-induced mixing acts as a negative feedback for its intensity, results from our study suggest that BLs may have potential implications for TC intensity prediction.

Balaguru, Karthik

303

Superior performance of African runners in warm humid but not in cool environmental conditions.  

PubMed

The purpose of this study was to examine the running performances and associated thermoregulatory responses of African and Caucasian runners in cool and warm conditions. On two separate occasions, 12 (n = 6 African, n = 6 Caucasian) well-trained men ran on a motorized treadmill at 70% of peak treadmill running velocity for 30 min followed by an 8-km self-paced performance run (PR) in cool (15 degrees C) or warm (35 degrees C) humid (60% relative humidity) conditions. Time to complete the PR in the cool condition was not different between groups ( approximately 27 min) but was significantly longer in warm conditions for Caucasian (33.0 +/- 1.6 min) vs. African (29.7 +/- 2.3 min, P < 0.01) runners. Rectal temperatures were not different between groups but were higher during warm compared with cool conditions. During the 8-km PR, sweat rates for Africans (25.3 +/- 2.3 ml/min) were lower compared with Caucasians (32.2 +/- 4.1 ml/min; P < 0.01). Relative rates of heat production were less for Africans than Caucasians in the heat. The finding that African runners ran faster only in the heat despite similar thermoregulatory responses as Caucasian runners suggests that the larger Caucasians reduce their running speed to ensure an optimal rate of heat storage without developing dangerous hyperthermia. According to this model, the superior running performance in the heat of these African runners can be partly attributed to their smaller size and hence their capacity to run faster in the heat while storing heat at the same rate as heavier Caucasian runners. PMID:12949014

Marino, Frank E; Lambert, Mike I; Noakes, Timothy D

2003-08-29

304

A regional modeling study of climate change impacts on warm-season precipitation in the U.S  

NASA Astrophysics Data System (ADS)

Changes in the character of precipitation have already been observed over much of the United States. In a warming climate, the impacts of these changes will likely be felt most strongly through changes in the intensity and frequency of climate extremes. With precipitation, this has potential to be highly disruptive to the environment and the economy. However, while current global climate models may provide acceptable simulations of precipitation on a continental scale, they are lacking when it comes to properly portraying the characteristics of warm-season precipitation over the U.S., creating uncertainty in the projections of future precipitation in this area of the world. Because predicting climate change is essential for mitigation, adaptation, and planning purposes, assessing the uncertainty associated with climate change projections and producing adequate simulations of present climate is important. This study proceeds in several parts to address this issue. It asks the overarching question of how climate change will impact warm-season precipitation over the U.S., focusing on precipitation extremes and the central U.S. region. To do so, the Weather Research and Forecasting (WRF) model is employed as a nested regional climate model to dynamically downscale output from the National Center for Atmospheric Research's (NCAR) Community Climate System Model (CCSM) version 3 and the National Center for Environmental Prediction (NCEP)/NCAR global reanalysis (NNRP). The latter is used for verification of late 20th century climate simulations from the WRF. In theory, the increase in horizontal resolution and sophistication of physical parameterizations in the WRF should improve the simulation of warm-season precipitation over the U.S., allowing a better representation of present climate and more reliable projections of future climate. As background, warm-season precipitation over the U.S. from current global climate models is assessed, as well as precipitation from current reanalyses in order to provide a basis for the comparison of model precipitation of the late 20th century. This study finds that the WRF is able to produce precipitation that is more realistic than that from the sources of its forcing (the CCSM and NNRP). It also diagnoses potential issues with and differences between all of the simulations completed. Specifically, the magnitude of heavy 6h average precipitation events and the frequency distribution of precipitation over the central U.S. is greatly improved. Projections from the WRF for late 21st century precipitation show decreases in average May-August (MJJA) precipitation, but an increase in the intensity of both heavy precipitation events and rain in general when it does fall. A decrease in the number of 6h periods with rainfall accounts for the overall decrease in average precipitation. The WRF also shows an increase in the frequency of very heavy to extreme 6h average events, but a decrease in the frequency of all events lighter than those over the central U.S. Overall, projections from this study suggest an increase in the frequency of both floods and droughts during the warm-season in the central U.S.

Bukovsky, Melissa Sue

305

Implication of global warming on air-conditioned office buildings in Australia  

Microsoft Academic Search

As climate change will entail new conditions for the built environment, the thermal behaviour of air-conditioned office buildings may also change. Using building computer simulations, the impact of warmer weather is evaluated on the design and performance of air-conditioned office buildings in Australia, including the increased cooling loads and probable indoor temperature increases due to a possibly undersized air-conditioning system,

Lisa Guan

2009-01-01

306

Formability of AZ31 magnesium alloy sheets at warm working conditions  

Microsoft Academic Search

Fine-grained AZ31 magnesium alloy sheets were prepared through hot-rolling process. To investigate the mechanical properties of the sheets, uniaxial tensile tests were conducted at various temperatures and strain rates. The formability of AZ31 alloy sheets at warm working conditions was evaluated by limit drawing ratio (LDR) tests and limit dome height (LDH) tests at temperatures from 50 to 240°C. It

K. F. Zhang; D. L. Yin; D. Z. Wu

2006-01-01

307

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

308

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

309

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

310

Managing Stream Temperatures for Climate Warming Adaptation with Selective Withdrawal from Reservoirs  

NASA Astrophysics Data System (ADS)

Climate warming is altering the flow and temperature regimes in California's Sierra Nevada mountain range by reducing snowpack, causing earlier runoff and raising stream temperatures. Managing reservoir releases for downstream temperatures is a promising adaptation option. In this study, we developed a linear programming model to optimally release water from multiple thermal layers in a seasonally stratified reservoir to minimize deviations from desired downstream temperatures. An explicit objective of the work was to develop a method that can be readily integrated into a watershed-scale, multi-reservoir optimization model using a node-link representation of system features. The objective function is to minimize managed temperature deviations from target temperatures based on the natural temperature regime. Thermal dynamics of reservoirs and streams are included in the constraint set. For a case study, the model is applied to Lake Spaulding, a multi-purpose reservoir in the western Sierra Nevada that thermally stratifies seasonally and that could be used to manage temperatures for a downstream cold water fishery. We demonstrate how the model can effectively manage releases from thermal pools when compared to only a single, low-level outlet (no selective withdrawal). The model hedges the release of cold water to decrease summer stream temperatures, but at a cost of warmer stream temperatures in the winter. This method can be extended to include other nearby reservoirs to optimally manage releases from multiple reservoirs for multiple downstream temperature targets to help buffer aquatic ecosystems against anticipated stream temperature increases.

Rheinheimer, D. E.; Lund, J. R.; Null, S.; Viers, J. H.

2011-12-01

311

24 CFR 3285.404 - Severe climatic conditions.  

Code of Federal Regulations, 2013 CFR

...COMMISSIONER, DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT MODEL MANUFACTURED HOME INSTALLATION STANDARDS Anchorage Against Wind § 3285.404 Severe climatic conditions. In frost-susceptible soil locations, ground anchor augers must be...

2013-04-01

312

Diagnosis of the summertime warm and dry bias over the U. S. Southern Great Plains in the GFDL climate model using a weather forecasting approach  

SciTech Connect

Weather forecasts started from realistic initial conditions are used to diagnose the large warm and dry bias over the United States Southern Great Plains simulated by the GFDL climate model. The forecasts exhibit biases in surface air temperature and precipitation within 3 days which appear to be similar to the climate bias. With the model simulating realistic evaporation but underestimated precipitation, a deficit in soil moisture results which amplifies the initial temperature bias through feedbacks with the land surface. The underestimate of precipitation is associated with an inability of the model to simulate the eastward propagation of convection from the front-range of the Rocky Mountains and is insensitive to an increase of horizontal resolution from 2{sup o} to 0.5{sup o} latitude.

Klein, S A; Jiang, X; Boyle, J; Malyshev, S; Xie, S

2006-07-11

313

Effects of airflow on body temperatures and sleep stages in a warm humid climate  

NASA Astrophysics Data System (ADS)

Airflow is an effective way to increase heat loss—an ongoing process during sleep and wakefulness in daily life. However, it is unclear whether airflow stimulates cutaneous sensation and disturbs sleep or reduces the heat load and facilitates sleep. In this study, 17 male subjects wearing short pyjamas slept on a bed with a cotton blanket under two of the following conditions: (1) air temperature (Ta) 26°C, relative humidity (RH) 50%, and air velocity (V) 0.2 m s-1; (2) Ta 32°C, RH 80%, V 1.7 m s-1; (3) Ta 32°C; RH 80%, V 0.2 m s-1 (hereafter referred to as 26/50, 32/80 with airflow, and 32/80 with still air, respectively). Electroencephalograms, electrooculograms, and mental electromyograms were obtained for all subjects. Rectal (Tre) and skin (Ts) temperatures were recorded continuously during the sleep session, and body-mass was measured before and after the sleep session. No significant differences were observed in the duration of sleep stages between subjects under the 26/50 and 32/80 with airflow conditions; however, the total duration of wakefulness decreased significantly in subjects under the 32/80 with airflow condition compared to that in subjects under the 32/80 with still air condition ( P < 0.05). Tre, Tsk, Ts, and body-mass loss under the 32/80 with airflow condition were significantly higher compared to those under the 26/50 condition, and significantly lower than those under the 32/80 with still air condition ( P < 0.05). An alleviated heat load due to increased airflow was considered to exist between the 32/80 with still air and the 26/50 conditions. Airflow reduces the duration of wakefulness by decreasing Tre, Tsk, Ts, and body-mass loss in a warm humid condition.

Tsuzuki, Kazuyo; Okamoto-Mizuno, Kazue; Mizuno, Koh; Iwaki, Tatsuya

2008-03-01

314

How may low-cloud radiative properties simulated in the current climate influence low-cloud feedbacks under global warming?  

NASA Astrophysics Data System (ADS)

The influence of cloud modelling uncertainties on the projection of the tropical low-cloud response to global warming is explored by perturbing model parameters of the IPSL-CM5A climate model in a range of configurations (realistic general circulation model, aqua-planet, single-column model). While the positive sign and the mechanism of the low-cloud response to climate warming predicted by the model are robust, the amplitude of the response can vary considerably depending on the model tuning parameters. Moreover, the strength of the low-cloud response to climate change exhibits a strong correlation with the strength of the low-cloud radiative effects simulated in the current climate. We show that this correlation primarily results from a local positive feedback (referred to as the “beta feedback”) between boundary-layer cloud radiative cooling, relative humidity and low-cloud cover. Based on this correlation and observational constraints, it is suggested that the strength of the tropical low-cloud feedback predicted by the IPSL-CM5A model in climate projections might be overestimated by about fifty percent.

Brient, F.; Bony, S.

2012-10-01

315

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

2012-12-06

316

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

317

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.

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

2012-01-01

318

Effects of 20th century warming and climate variability on flood risk in the western U.S  

Microsoft Academic Search

Using precipitation and temperature data for the 20th century in combination with a macroscale hydrologic model, we evaluate changes in flood risk in the western U.S. associated both with century-scale warming and interannual climate variations. In addition, we examine the implications of apparent increases in precipitation variability over the region since the mid-1970s. We use detrended temperature data representing early

Alan F. Hamlet; Dennis P. Lettenmaier

2007-01-01

319

The interacting effects of temperature, ground disturbance, and herbivory on seedling establishment: implications for treeline advance with climate warming  

Microsoft Academic Search

Thermal control of treeline position is mediated by local environmental and ecological factors, making trends in treeline\\u000a migration difficult to extrapolate geographically. We investigated the ecological dynamics of conifer establishment at treeline\\u000a in the Mealy Mountains (Labrador, Canada) and the potential for its expansion with climate warming. Available seedbed and\\u000a tree seedling emergence in the treeline ecotone were monitored, and

Anne Munier; Luise Hermanutz; John D. Jacobs; Keith Lewis

2010-01-01

320

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

2012-03-30

321

Mid-twenty-first century warm season climate change in the Central United States. Part I: regional and global model predictions  

NASA Astrophysics Data System (ADS)

A regional climate model (RCM) constrained by future anomalies averaged from atmosphere-ocean general circulation model (AOGCM) simulations is used to generate mid-twenty-first century climate change predictions at 30-km resolution over the central U.S. The predictions are compared with those from 15 AOGCM and 7 RCM dynamic downscaling simulations to identify common climate change signals. There is strong agreement among the multi-model ensemble in predicting wetter conditions in April and May over the northern Great Plains and drier conditions over the southern Great Plains in June through August for the mid-twenty-first century. Projected changes in extreme daily precipitation are statistically significant over only a limited portion of the central U.S. in the RCM constrained with future anomalies. Projected changes in monthly mean 2-m air temperature are generally consistent across the AOGCM ensemble average, North American Regional Climate Change Assessment Program RCM ensemble average, and RCM constrained with future anomalies, which produce a maximum increase in August of 2.4-2.9 K over the northern and southern Great Plains and Midwest. Changes in extremes in daily 2-m air temperature from the RCM downscaled with anomalies are statistically significant over nearly the entire Great Plains and Midwest and indicate a positive shift in the warm tail of the daily 2-m temperature distribution that is larger than the positive shift in the cold tail.

Patricola, Christina M.; Cook, Kerry H.

2013-02-01

322

Expansion of dwarf birch in subarctic Québec: linking radial growth to climate warming  

NASA Astrophysics Data System (ADS)

In subarctic regions of North America, shrub species have been shown to increase in abundance in response to recent climate change. At the forest-tundra ecotone in northern Québec, the shrub layer is dominated by dwarf birch (Betula glandulosa Michx.), a deciduous species that can reproduce sexually via the production of viable seeds or asexually through clonal growth. Its morphological plasticity is often mentioned to explain its high sensibility to experimental warming. In this study, our objectives were to evaluate if recent warming recorded in subarctic Québec has resulted in dwarf birch expansion and densification in the last few decades and in an increase in its radial growth. This study took place in the Boniface river region, Nunavik (57° 45’ N, 76° 20’ W). In order to quantify the change in birch cover, we compared two sets of orthorectified aerial photographs (July 1957 and July 2008; resolution 1.0m and 0.5m, respectively). Fifty sites located on well-drained substrate ranging from 8 000 and 14 400 m2 have been selected. For each site, a 16m2-cell grid was superimposed on both orthoimages and shrub cover class was estimated in each cells. Preliminary results suggest that shrub cover increase ranges from 17.02 to 54.03%. No site showed a decrease of mean shrub cover between 1957 and 2008. On the other hand, we have found a decline in the percentage of cells having no shrub cover, from 46% in 1957 to 17% in 2008. An exhaustive ground truthing exercise confirmed that Betula glandulosa was the major shrub species responsible for the increase in shrub cover in the studied sites. The rapid expansion and densification of the shrub layer could have important ecological consequences in the region. Dense thickets of dwarf birch could actually interfere with future tree establishment and limit the progression of the latitudinal treeline in the short term. The dendrochronological analysis is based on 360 individuals of dwarf birch (40 individuals taken from 9 different sites). Preliminary results of this analysis revealed that Betula glandulosa growth is related to summer temperatures. Therefore, increased radial growth could translate to greater viable seed production and greater seedling establishment.

Ropars, P.; Boudreau, S.

2010-12-01

323

Acute dopamine/noradrenaline reuptake inhibition enhances human exercise performance in warm, but not temperate conditions  

PubMed Central

Nine healthy endurance-trained males were recruited to examine the effect of a dual dopamine/noradrenaline reuptake inhibitor on performance, thermoregulation and the hormonal responses to exercise. Subjects performed four trials, ingesting either a placebo (pla) or 2 × 300 mg bupropion (bup), prior to exercise in temperate (18°C) or warm (30°C) conditions. Trials consisted of 60 min cycle exercise at 55% Wmax immediately followed by a time trial (TT). TT performance in the heat was significantly improved by bupropion (pla: 39.8 ± 3.9 min, bup: 36.4 ± 5.7 min; P = 0.046), but no difference between treatments was apparent in temperate conditions (pla: 30.6 ± 2.2 min, bup: 30.6 ± 1.9 min; P = 0.954). While TT power output was consistently lower in the heat when compared to temperate conditions, this decrement was attenuated by bupropion. At the end of the TT in the heat, both core temperature (pla 39.7 ± 0.3°C, bup 40.0 ± 0.3°C; P = 0.017) and HR (pla 178 ± 7 beats min?1, bup 183 ± 12 beats min?1; P = 0.039), were higher in the bupropion trial than in the placebo. Circulating pituitary and adrenal hormone concentrations increased throughout exercise in all trials. Circulating serum prolactin was elevated above temperate levels during exercise in a warm environment (P < 0.001). These data indicate that performance in warm conditions is enhanced by acute administration of a dual dopamine/noradrenaline reuptake inhibitor. No such effect was apparent under temperate conditions. It appears that bupropion enabled subjects to maintain a greater TT power output in the heat with the same perception of effort and thermal stress reported during the placebo trial, despite the attainment of a higher core temperature.

Watson, Phillip; Hasegawa, Hiroshi; Roelands, Bart; Piacentini, Maria Francesca; Looverie, Roel; Meeusen, Romain

2005-01-01

324

Late Noachian to Hesperian climate change on Mars: Evidence of episodic warming from transient crater lakes near Ares Vallis  

Microsoft Academic Search

The Ares Vallis region is surrounded by highland terrain containing both degraded and pristine large impact craters that suggest a change in climate during the Late Noachian-Early Hesperian, from warmer, wetter conditions to colder, dryer conditions. However, the regional occurrence of Hesperian-age crater outlet channels indicates that this period on Mars was characterized by episodic climate fluctuations that caused transient

Nick Warner; Sanjeev Gupta; Shih-Yuan Lin; Jung-Rack Kim; Jan-Peter Muller; Jeremy Morley

2010-01-01

325

The influence of climate change and the timing of stratospheric warmings on Arctic ozone depletion  

Microsoft Academic Search

Satellite data are presented showing the timing of sudden warmings in the lower stratosphere during the winters 1979-1992. A three-dimensional dynamical-radiative-photochemical model is used to establish how Arctic ozone depletion will respond to a doubling of CO2 according to the timing of the warmings. In a series of idealized experiments the timing of the warmings is varied by specifying different

John Austin; Neal Butchart

1994-01-01

326

The dynamic response of the Greenland and Antarctic ice sheets to multiple-century climatic warming  

SciTech Connect

New calculations were performed to investigate the combined response of the Greenland and Antarctic ice sheets to a range of climatic warming scenarios over the next millennium. Use was made of fully dynamic 3D thermomechanic ice sheet models, which were coupled to a two-dimensional climate model. The experiments were initialized with simulations over the last two glacial cycles to estimate the present evolution and were subsequently forced with temperature scenarios resulting from greenhouse emission scenarios which assume equivalent CO{sub 2} increases of two, four, and eight times the present (1990 A.D.) value by the year 2130 A.D. and a stabilization after that. The calculations brought to light that during the next century (short-term effect), the background evolution trend would dominate the response of the Antarctic ice sheet but would be negligible for the Greenland ice sheet. On that timescale, the Greenland and Antarctic ice sheets would roughly balance one another for the middle scenario (similar to the IPCC96 IS92a scenario), with respective contributions to the worldwide sea level stand on the order of about {+-}10 cm. On the longer term, however, both ice sheets would contribute positively to the worldwide sea level stand and the most important effect would come from melting on the Greenland ice sheet. Sensitivity experiments highlighted the role of ice dynamics and the height-mass-balance feedback on the results. It was found that ice dynamics cannot be neglected for the Greenland ice sheet, not even on a century timescale, but becomes only important for Antarctica on the longer term. The latter is related to an increased outflow of ice into the ice shelves and to the grounding-line retreat of the west Antarctic ice sheet, which are both found to be sensitive to basal melting below ice shelves and the effective viscosity of the ice shelves. Stretching parameters to their limits yielded a combined maximum rate of sea level rise of 85 cm century{sup {minus}1}, of which 60 cm would originate from the Greenland ice sheet alone.

Huybrechts, P. [Vrije Universiteit Brussel, Brussels (Belgium). Dept. Geografie; Wolde, J. de [Universiteit Utrecht (Netherlands). Instituut voor Marien en Atmosferische Onderzoek

1999-08-01

327

Climatic impacts of fresh water hosing under Last Glacial Maximum conditions: a multi-model study  

NASA Astrophysics Data System (ADS)

Fresh water hosing simulations, in which a fresh water flux is imposed in the North Atlantic to force fluctuations of the Atlantic Meridional Overturning Circulation, have been routinely performed, first to study the climatic signature of different states of this circulation, then, under present or future conditions, to investigate the potential impact of a partial melting of the Greenland ice sheet. The most compelling examples of climatic changes potentially related to AMOC abrupt variations, however, are found in high resolution palaeo-records from around the globe for the last glacial period. To study those more specifically, more and more fresh water hosing experiments have been performed under glacial conditions in the recent years. Here we compare an ensemble constituted by 11 such simulations run with 6 different climate models. All simulations follow a slightly different design, but are sufficiently close in their design to be compared. They all study the impact of a fresh water hosing imposed in the extra-tropical North Atlantic. Common features in the model responses to hosing are the cooling over the North Atlantic, extending along the sub-tropical gyre in the tropical North Atlantic, the southward shift of the Atlantic ITCZ and the weakening of the African and Indian monsoons. On the other hand, the expression of the bipolar see-saw, i.e., warming in the Southern Hemisphere, differs from model to model, with some restricting it to the South Atlantic and specific regions of the southern ocean while others simulate a widespread southern ocean warming. The relationships between the features common to most models, i.e., climate changes over the north and tropical Atlantic, African and Asian monsoon regions, are further quantified. These suggest a tight correlation between the temperature and precipitation changes over the extra-tropical North Atlantic, but different pathways for the teleconnections between the AMOC/North Atlantic region and the African and Indian monsoon regions.

Kageyama, M.; Merkel, U.; Otto-Bliesner, B.; Prange, M.; Abe-Ouchi, A.; Lohmann, G.; Ohgaito, R.; Roche, D. M.; Singarayer, J.; Swingedouw, D.; Zhang, X.

2013-04-01

328

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

329

Variability in krill biomass links harvesting and climate warming to penguin population changes in Antarctica  

PubMed Central

The West Antarctic Peninsula (WAP) and adjacent Scotia Sea support abundant wildlife populations, many of which were nearly extirpated by humans. This region is also among the fastest-warming areas on the planet, with 5–6 °C increases in mean winter air temperatures and associated decreases in winter sea-ice cover. These biological and physical perturbations have affected the ecosystem profoundly. One hypothesis guiding ecological interpretations of changes in top predator populations in this region, the “sea-ice hypothesis,” proposes that reductions in winter sea ice have led directly to declines in “ice-loving” species by decreasing their winter habitat, while populations of “ice-avoiding” species have increased. However, 30 y of field studies and recent surveys of penguins throughout the WAP and Scotia Sea demonstrate this mechanism is not controlling penguin populations; populations of both ice-loving Adélie and ice-avoiding chinstrap penguins have declined significantly. We argue in favor of an alternative, more robust hypothesis that attributes both increases and decreases in penguin populations to changes in the abundance of their main prey, Antarctic krill. Unlike many other predators in this region, Adélie and chinstrap penguins were never directly harvested by man; thus, their population trajectories track the impacts of biological and environmental changes in this ecosystem. Linking trends in penguin abundance with trends in krill biomass explains why populations of Adélie and chinstrap penguins increased after competitors (fur seals, baleen whales, and some fishes) were nearly extirpated in the 19th to mid-20th centuries and currently are decreasing in response to climate change.

Trivelpiece, Wayne Z.; Hinke, Jefferson T.; Miller, Aileen K.; Reiss, Christian S.; Trivelpiece, Susan G.

2011-01-01

330

Factors affecting the efficacy of live poliovirus vaccine in warm climates  

PubMed Central

A virologically controlled field trial was conducted with live monovalent type 1 poliovirus vaccine in children aged 3-30 months living in a rural area of Uganda, in an attempt to find out the reason for the poor efficacy of such vaccine often observed in countries with a warm climate. Groups of breast-fed and of artificially fed infants received the vaccine orally, either alone or mixed with horse serum prepared against partly purified human gamma-globulin. Irrespective of the diet, the “take rate”—measured by the rates of vaccine virus excretion and of antibody conversion—was found to be poor when the vaccine was given alone but satisfactory when it was given together with the horse antiserum. However, the extent and duration of vaccine virus multiplication in the intestinal tract proved to be limited and the mean antibody level elicited by the vaccination, irrespective of the schedule of vaccine administration, was low. These results, besides indicating that breast-feeding does not influence the efficacy of vaccination in the age groups studied, revealed the presence of an inhibitor in the alimentary tract. This inhibitor acts against the multiplication of vaccine virus, which may be blocked by antibodies in the horse antiserum for a limited period at the time of vaccination. Interference between the enteroviruses and the vaccine strain was also found to be responsible for decreasing the efficacy of vaccination, though its role was secondary to that of the inhibitor. Revaccination experiments showed that the effects of both inhibitor and interference may be overcome by repeated administration of the vaccine.

Domok, I.; Balayan, M. S.; Fayinka, O. A.; Skrtic, N.; Soneji, A. D.; Harland, P. S. E. G.

1974-01-01

331

Climate warming and disease risks in temperate regions--Argulus coregoni and Diplostomum spathaceum as case studies.  

PubMed

The link between climate changes and disease risks from various pathogens has been increasingly recognized. The effect of climatic factors on host-parasite population dynamics is particularly evident in northern latitudes where the occurrence and transmission of parasites are strongly regulated by seasonality-driven changes in environmental temperatures. Shortened winter periods would increase growth potential of many parasite populations. The ways in which climate warming could affect life history dynamics of the directly transmitted crustacean ectoparasite Argulus coregoni and complex life cycle trematode Diplostomum spathaceum, which frequently cause problems in northern fish farming, are discussed. Increased problems for fish farming are predicted in terms of increased infection pressure from these parasites in future. This would increase problems associated with infections and increase the use of expensive management protocols with high environmental impact. PMID:16768854

Hakalahti, T; Karvonen, A; Valtonen, E T

2006-06-01

332

Spatiotemporal distribution of threatened high-latitude snowbed and snow patch habitats in warming climate  

NASA Astrophysics Data System (ADS)

We studied the interannual variation of late summer snow covered area (SCA), i.e. snowbeds and permanent snow patches, in northern Finland and analyzed the role of topographical factors and climatic conditions on the recent and future occurrence of summer snow. SCA for the years 2000, 2004, 2006 and 2009 was derived from Landsat images using a normalized difference snow index (NDSI). Late summer SCA varied notably between the years (1.5-23.0 km2). A major part of the late summer snow was located above 900-1000 m and on northern and eastern slopes. A generalized additive model (GAM) showed that the number of years with snow present in 1 km grid squares was strongly positively related to altitude and terrain ruggedness. Parallel examination of interannual variation of SCA and climatic conditions showed that snow cover declines were linked to relatively low snowfall-to-rainfall ratios. Annual mean air temperatures, particularly spring and early winter temperatures, showed increasing trends during the study period. Projected increases in air temperatures and rainfall suggest earlier and more efficient snow melt in the future. This may threaten the occurrence of species and communities related to snowbeds and decrease the ?-diversity of the landscape, and could also affect ecosystem services of the region.

Kivinen, Sonja; Kaarlejärvi, Elina; Jylhä, Kirsti; Räisänen, Jouni

2012-09-01

333

Climate condition in the Central Europe during the Weichselian Ice Sheet according to the Educational Global Climate Modeling Project  

NASA Astrophysics Data System (ADS)

The expansion and retreat of the ice sheet is controlled by climate changes, and from the other hand, a huge ice mass influences on the climate in the regional scale. This mechanism is commonly known as the fact but often without making reconstruction by using climatological modeling. The purpose of our study is to reconstruct the climate condition during the Weichselian Ice Sheet in the Central Europe, especially for Poland and surrounded countries. The Global Climate Model (GCM) is made for predicting climate, but simplified version can be useful for reconstructing paleoclimate. Hence, the simple initial conditions and surface data proposed by the Educational version of the GCM was applied. In our study we used a simplified version of the GCM to calculate main climate characteristics within the time limits c. 21 000 BP - 18 000 BP, which has been previously invented on Columbia University. The model is constructed on grid with a horizontal resolution 8° latitude by 10° longitude and was establish for modeling most of weather conditions based on available paleoclimate data. It is possible to estimate the probable climate condition along the southern ice sheets margin on the basis of output from the GCM and GIS modeling techniques. Above the ice mass occurs local high pressure area, which seriously interfered on atmospheric circulation. Whereas the low pressure systems in the southern part of continent may caused permanent barometric situation, which stimulates wind directions as well as the precipitable water available in the mass of air. The climate on the east-south border of ice margin was colder and drier than on the west-south region, where it was more ocean-reliable and gentle with higher temperatures. The differences in temperature between the western and eastern part of the Central Europe reached few centigrade. Against a background of the mean paleoclimatic situation in the Central Europe there is coming out a question about the particular paleoclimate condition in Poland. In this area occurred a huge ice-lobe, distinct in the geomorphology, during the Weichselian Ice Sheet. Authors try to define the role of such a big ice-barrier on the climate changes at the foreland, between the western and eastern side. It is necessary to consider the ice cap thickness in the lobe estimated from separately prepared in GIS software (GRASS) 3D ice-sheet surface elevation model, together with the climatic data from the GCM for regional situation. The results of modeling are also related to available abiotic parameters for Poland. Finally, it is suggested that the ice-lobe was high enough barrier to cause the differences in temperature distribution due to limitation of delivery the warm Atlantic air masses to the eastern region. It has also significant impact on local wind field, especially in transition areas.

Szuman, Izabela; Czernecki, Bartosz

2010-05-01

334

Evidence for neuromuscular fatigue during high-intensity cycling in warm, humid conditions  

Microsoft Academic Search

The purpose of this study was to examine and describe the neuromuscular changes associated with fatigue using a self-paced\\u000a cycling protocol of 60-min duration, under warm, humid conditions. Eleven subjects [mean (SE) age 21.8 (0.8)?years; height\\u000a 174.9 (3.0)?cm; body mass 74.8 (2.7)?kg; maximum oxygen consumption 50.3 (1.8)?ml??kg??min?1] performed one 60-min self-paced cycling time trial punctuated with six 1-min “all out”

Derek Kay; Frank E. Marino; Jack Cannon; Alan St Clair Gibson; Mike I. Lambert; Timothy D. Noakes

2001-01-01

335

Response of hurricane-type vortices to global warming as simulated by ARPEGE-Climat at high resolution  

NASA Astrophysics Data System (ADS)

Atlantic hurricanes and their sensitivity to anthropogenic warming are investigated using very high (0.5°×0.5° over the Atlantic domain) resolution global simulations. The ARPEGE-Climat variable resolution grid demonstrates its usefulness in regional climate studies since resolution can be multiplied by a factor of 2.5 over the domain of interest compared to a uniform grid, for a similar computer cost. The question of hurricane characteristics dependence on anthropogenic warming is tackled trough the implementation of a tracking method. Changes in the total number, as well as locations, of hurricanes appear to depend more on sea surface temperature (SST) spatial patterns anomaly than Atlantic mean intensity, essentially through the change in large scale vertical wind shear. A uniform SST anomaly forcing produces increased and eastward shifted systems while a spatially contrasted anomaly leads to a decrease. Comparison between cyclogenesis density calculated from tracking or large scale combined variables (as a modified Gray parameter) brings some confidence in the use of the latter to investigate low resolution simulations. Mean hurricane dynamical characteristics are weakly changed by the warming but precipitation core and latent heat flux are enhanced in all scenarios.

Chauvin, Fabrice; Royer, Jean-François; Déqué, Michel

2006-09-01

336

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

Microsoft Academic Search

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.

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

2008-01-01

337

Comparison of global warming impacts of automobile air-conditioning concepts  

SciTech Connect

The global warming impacts of conventional vapor compression automobile air conditioning using HFC-134a are compared with the potential impacts of four alternative concepts. Comparisons are made on the basis of total equivalent warming impact (TEWI) which accounts for the effects of refrigerant emissions, energy use to provide comfort cooling, and fuel consumed to transport the weight of the air conditioning system. Under the most favorable assumptions on efficiency and weight, transcritical compression using CO{sub 2} as the refrigerant and adsorption cooling with water and zeolite beds could reduce TEWI by up to 18%rlative to HFC-134a compression air conditioning. Other assumptions on weight and efficiency lead to significant increases in TEWI relative to HFC-134a, and it is impossible to determine which set of assumptios is valid from existing data, Neither Stirling cycle or thermoelectric cooling will reduce TEWI relative to EFC-134a. Brief comments are also made concerning technical barriers that must be overcome for succesful development of the new technologies.

NONE

1995-12-31

338

Effects of Permafrost on the Rate of Spruce Migration During Climate Warming  

NASA Astrophysics Data System (ADS)

Although white spruce has advanced into tundra ecosystems throughout Alaska since the late 1800s, presumably in response to a regional increase in temperature, there is high variance in the magnitude of change in treeline position among arctic treeline sites. We investigated the role of permafrost as a modulator of vegetation response to climate by estimating the migration rate of spruce advancing into lowland sites with very poorly drained soils and upland sites with more well-drained soils. Migration rates were estimated from published reconstructions of spruce population dynamics at 2 lowland and 4 upland sites on the Seward Peninsula, Alaska. Migration rate was calculated by dividing the distance between two locations along an advancing front by the difference in stand age at the two locations. We estimated the hypothetical effect of variation in migration rate on the areal extent of land cover change over a 100 year period by multiplying the length of the forest-tundra boundary on the Seward Peninsula by the estimated migration rates. Migration rates in upland sites (129 m/yr) were greater than those in lowland sites (0.2 m/yr). Differences in estimated spruce migration rates had a large effect on the land area that could hypothetically be affected by spruce expansion. Migration rates equivalent to those found in upland sites would result in spruce colonizing 33% of the treeless area of the Seward Peninsula over a 100 year period, while rates equivalent to those found in lowland sites would result in 0.05% of the treeless area being colonized by spruce. Three hypotheses may explain the variation in migration rates in the two types of sites. First, differences in migration rate may reflect different climatic histories. The upland and lowland sites are separated by <10 km, however, so it is unlikely that the rate of warming differed significantly between them. Second, the density of spruce behind the advancing front may limit seed availability and thus reduce migration rate. Spruce density behind the advancing front at lowland sites was an order of magnitude greater than in upland sites, however, so source population density is not a likely explanation for the slow migration rate from lowland sites. Finally, migration into lowland tussock tundra may be limited by the availability of suitable microsites. Two lines of evidence support this hypothesis. First, lowland sites have extremely high subsurface soil moisture, which may inhibit spruce colonization. Second, prior research has shown that spruce preferentially colonize lowland tundra in thermokarst-affected sites with improved drainage. Our results thus suggest that permafrost, by impeding soil drainage, reduces the rate of the transition from tundra to forest vegetation, and therefore acts to dampen the response rate of forest vegetation to climate.

Lloyd, A. H.; Hinzman, L.; Fastie, C. L.; Yoshikawa, K.; Rupp, S.

2003-12-01

339

Keeping up with a warming world; assessing the rate of adaptation to climate change  

PubMed Central

The pivotal question in the debate on the ecological effects of climate change is whether species will be able to adapt fast enough to keep up with their changing environment. If we establish the maximal rate of adaptation, this will set an upper limit to the rate at which temperatures can increase without loss of biodiversity. The rate of adaptation will primarily be set by the rate of microevolution since (i) phenotypic plasticity alone is not sufficient as reaction norms will no longer be adaptive and hence microevolution on the reaction norm is needed, (ii) learning will be favourable to the individual but cannot be passed on to the next generations, (iii) maternal effects may play a role but, as with other forms of phenotypic plasticity, the response of offspring to the maternal cues will no longer be adaptive in a changing environment, and (iv) adaptation via immigration of individuals with genotypes adapted to warmer environments also involves microevolution as these genotypes are better adapted in terms of temperature, but not in terms of, for instance, photoperiod. Long-term studies on wild populations with individually known animals play an essential role in detecting and understanding the temporal trends in life-history traits, and to estimate the heritability of, and selection pressures on, life-history traits. However, additional measurements on other trophic levels and on the mechanisms underlying phenotypic plasticity are needed to predict the rate of microevolution, especially under changing conditions. Using this knowledge on heritability of, and selection on, life-history traits, in combination with climate scenarios, we will be able to predict the rate of adaptation for different climate scenarios. The final step is to use ecoevolutionary dynamical models to make the link to population viability and from there to biodiversity loss for those scenarios where the rate of adaptation is insufficient.

Visser, Marcel E

2008-01-01

340

Responses of mountain forested watersheds to climate warming: interactions among snowmelt, soil/geology and vegetation water use (Invited)  

NASA Astrophysics Data System (ADS)

At regional scales, spatial variation in eco-hydrologic processes is a complex function of geology, soil, topography, climate and vegetation patterns. Understanding how these different controls vary and interact remains a key challenge for climate change impact assessment. In snow-dominated mountain environments, there is growing evidence that reduced snow accumulation and earlier melt is already occurring and is an important driver of summer streamflow and ecosystem responses. Modelling these responses requires estimation not only of the spatial pattern of melt response to warming, but also the convolution of these spatial patterns with vegetation water use and subsurface drainage. We use a coupled process-based model of ecosystem hydrologic and carbon cycling, RHESSys, to demonstrate that soil moisture drainage and storage characteristics exert a significant control on how forest water use, and streamflow respond to earlier snowmelt. We focus our modeling scenarios on sites with measurements of streamflow, and vegetation growth that can be used to evaluate model performance. We then use the model to show how the combined changes in snowmelt and terrestrial ecosystem responses alter streamflow regimes and may have important implications for aquatic and human communities. These modeling studies provide an expanded perspective on landscape-level sensitivities to climate warming, and can provide guidance for the strategic design of data assimilation and monitoring strategies.

Tague, C.; Choate, J.; Dugger, A. L.; Garcia, E.; Groulx, D.; Son, K.

2010-12-01

341

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

PubMed

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

Penton, C Ryan; Stlouis, Derek; Cole, James R; Luo, Yiqi; Wu, Liyou; Schuur, E A G; Zhou, Jizhong; Tiedje, James M

2013-09-06

342

A method to treat climate changes of year-to-year variations in the pseudo-global-warming method as a dynamical downscaling  

NASA Astrophysics Data System (ADS)

The pseudo-global-warming (PGW) method is a time-slice dynamical downscaling one developed by Kimura and Kitoh (2007) to obtain regional climate change information with finer resolutions. In the present climate experiment, regional climate model (RCM) experiment is carried out with objective analysis data (ANAL) as the lateral boundary conditions. On the other hand, in the future climate experiment, the lateral boundary conditions are the sum of the ANAL and the difference between the present and future climates by an atmosphere-ocean general circulation model (AOGCM). The advantage of this method is that the influences of biases of the AOGCMs are reduced. In addition, the number of downscaling experiments could be reduced in multi-model problems, namely, a RCM experiment result with the boundary conditions created by a multi-model ensemble mean of AOGCMs seems to be similar to the average of the results of RCMs with their AOGCMs. However, PGW method involves some problems. One of them is that climate changes in year-to-year variations are ignored. To overcome this problems, a new method is introduced. In the new method, a mean climatological difference of a AOGCM is added to ANAL in future climate experiment, which is the same as PGW method. Next, the year-to-year variation term of ANAL, AOGCM in the present climate (GCM-P), and that in the future climate (GCM-F) are normalized in each level and element of ANAL to X’a, X’p, and X’f, respectively. The eigenvector of X’a (Va) is extracted by Principal Component Analysis (PCA). Only Va is trusted among the variations of ANAL, GCM-P, and GCP-F. Thus, the coefficients (Ta, Tp, and Tf) of the Multiple Regression Analysis (MRA) with Va are examined, and a coefficient (Tw) for Va are newly estimated as the variation term of boundary conditions of RCM in the future climate (X’w). To create Tw, three-step calculations are included in the estimation. First, a matrix operator, that the covariance of coefficients matrix of GCM-P is changed into that of GCM-P, is calculated using the lower triangle matrix made by the Cholesky decomposition. The operation is carried out for Ta, and Tw1 and its covariance Cw1 are estimated. Second, the reliability of Tw1 and Cw1 are investigated. The Cw1 is modified using a weight matrix W into Cw2. The details are omitted, but the unreliable variation mode is mostly replaced by that of the ANAL. Tw2 are calculated from Cw2. Third, The total amplitude of the variations is adjusted. The total amplitude of Cw2 (Pw), that is a trace of orthogonalized Cw2, is somewhat small, because all variations of Tw could not be expressed by Va. To amplify Pw, Cw is defined as Qw/Pw*Cw2. Here, Qw=Qf/Qp*Qa. Qa (Qp, Qf) is a trace of covariance of coefficient, which is estimated by a PCA and a MRA with ANAL (GCM-P, GCM-F). The final coefficient Tw is calculated by Cw. Consequently, a suitable year-to-year variation pattern is created for the boundary conditions of PGW experiment in the future climate. Here, differences of the boundary conditions between the present and future climate are constant in the normal PGW method. However, these vary with year in the new method. In the multi-model downscaling problem, the statistical operations such as the average are carried out for Cw.

Wakazuki, Y.; Hara, M.; Kimura, F.; Regional Climate Modeling Research Team

2010-12-01

343

Recent warming in Greenland in a long-term instrumental (1881-2012) climatic context: I. Evaluation of surface air temperature records  

NASA Astrophysics Data System (ADS)

We present an updated analysis of monthly means of daily mean, minimum and maximum surface air temperature (SAT) data from Greenland coastal weather stations and from a long-running site on the Greenland ice sheet, and analyse these data for evidence of climate change, especially focusing on the last 20 years but using the whole periods of available records (some since 1873). We demonstrate very strong recent warming along the west coast of Greenland, especially during winter (locally >10?°C since 1991), and rather weaker warming on the east Greenland coast, which is influenced by different oceanographic/sea-ice and meteorological synoptic forcing conditions to the rest of Greenland. Coastal Greenland seasonal mean SAT trends were generally 2-6?°C, strongest in winter (5.7?°C) and least in summer and autumn (both 2.2?°C), during 1981-2011/12. Since 2001 Greenland mean coastal SAT increased significantly by 2.9?°C in winter and 0.8?°C in summer but decreased insignificantly by 1.1?°C in autumn and 0.2?°C in spring, during a period when there was little net change (? ± 0.1?°C) in northern hemisphere temperatures. SAT means for the latest 2001-11/12 decade were significantly in excess of those for peak decadal periods during the Early Twentieth Century Warm Period only in summer and winter, and not significantly greater in spring and autumn. Summer SAT increases in southern Greenland for the last 20 years were generally greater for maximum than minimum temperatures. By contrast, in winter, the recent warming was greater for minimum than maximum temperatures. The greatest SAT changes in all seasons are seen on Greenland’s west coast. SAT changes on the ice sheet and a key marginal glacier closely followed nearby coastal temperatures over the last 20 years.

Hanna, Edward; Mernild, Sebastian H.; Cappelen, John; Steffen, Konrad

2012-12-01

344

Method of relieving pain and treating inflammatory conditions in warm-blooded animals  

US Patent & Trademark Office Database

The present invention provides a method of relieving pain and of treating inflammatory conditions in warm-blooded animals, including humans, which comprises administering to a warm-blooded animal suffering from an inflammatory condition a phenyl-alkanoic acid salt of the general formula: ##STR1## wherein R.sub.1 is a hydrogen atom or a methyl radical, R.sub.2 is a halogen atom or an alkyl radical containing up to 5 carbon atoms, which may be straight-chained or branched, for example an isobutyl radical, or is a cyclohexyl radical or is a phenoxy or benzoyl radical, which may be substituted by one or two halogen atoms, R.sub.3 is a hydrogen atom or an allyloxy radical or R.sub.2 and R.sub.3, together with the phenyl nucleus to which they are attached, represent a naphthyl ring system containing a methoxy substituent, B is a primary, secondary or tertiary amino group or a guanidino or amidino group and n is a whole number not greater than 5, for example B is an amino group and n is 3 (ornithine), B is an amino group and n is 4 (lysine) or B is a guanidino radical and n is 3 (arginine).

1981-07-21

345

Investigating climatic drivers of the warming hole through empirical downscaling of eastern U.S. summertime maximum temperatures  

NASA Astrophysics Data System (ADS)

Global average temperatures have increased over the past century, but not all regions of the world have experienced warming. The central United States has experienced less warming than western and eastern portions of the country, with some stations experiencing cooling trends during the period of 1948-2009, leading researchers to dub the area a "warming hole." The causes of this anomaly have been investigated via general circulation models (GCMs) and regional climate model downscaling of GCM output, but conclusions have been limited. This research identifies important drivers of June, July, and August (JJA) mean maximum daily temperature (Tmax) in the region which includes the "warming hole" by developing a model for Tmax using empirical downscaling of large scale variables and local precipitation. First, robust trend analysis is used to determine temperature trends across the country for two time periods: 1948--2009, and 1978--2009; and to locate stations which have experienced cooling, or minimal warming. Second, 19 surface and upper air variables are investigated to identify the optimal independent predictors of Tmax. Station-by-station models of T max are produced from National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis sea level pressure, 500 mb geopotential heights, total (meridional and zonal) 850 mb winds in the area of frequent LLJs, as well as station precipitation and assessed for quality. Measures of skill include analysis of error and variance in the modeled time series, as well values of beta-weighted regression coefficients. Third, trends from the modeled time series are calculated and compared with the observed trends. The models show that 500 mb heights have a strong positive correlation with Tmax across the study area, while precipitation widely and uniformly correlates with lower Tmax. Sea level pressure has a negative correlation with Tmax in much of the study area. The LLJ predictor provides novel insight into the climatic drivers in the vicinity of the warming hole, indicating that moisture advection driving nocturnal precipitation plays a role in depressing Tmax.

Wagner, Audrey Romaine

346

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.

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

2013-01-01

347

Global negative vegetation feedback to climate warming responses of leaf litter decomposition rates in cold biomes  

Microsoft Academic Search

Whether climate change will turn cold biomes from large long-term carbon sinks into sources is hotly debated because of the great potential for ecosystem-mediated feedbacks to global climate. Critical are the direction, magnitude and generality of climate responses of plant litter decomposition. Here, we present the first quantitative analysis of the major climate-change-related drivers of litter decomposition rates in cold

Johannes H. C. Cornelissen; Bodegom van P. M; M. A. P. A. Aerts; T. V. Gallaghan; Logtestijn van R. S. P; Juha Alatalo; F. Stuart Chapin; Renato Gerdol; Jon Gudmundsson; Dylan Gwynn-Jones; Anne E. Hartley; David S. Hik; Annika Hofgaard; I. S. Jonsdottir; Staffan Karlsson; Julia A. Klein; Jim Laundre; Borgthor Magnusson; A. Michelsel; Ulf Molau; Vladimir G. Onipchenko; Helen M. Quested; Sylvi M. Sandvik; Inger K. Schmidt; Gus R. Shaver; B. Solhleim; Nadejda A. Soudzilovskaia; A. Stenstrom; Anne Tolvanen; O. Totland; Naoya Wada; Jeffrey M. Welker; Xinquan Zhao

2007-01-01

348

Regional climatic warming drives long-term community changes of British marine fish  

Microsoft Academic Search

Climatic change has been implicated as the cause of abundance fluctuations in marine fish populations worldwide, but the effects on whole communities are poorly understood. We examined the effects of regional climatic change on two fish assemblages using independent datasets from inshore marine (English Channel, 1913-2002) and estuarine environments (Bristol Channel, 1981-2001). Our results show that climatic change has had

Martin J. Genner; David W. Sims; Victoria J. Wearmouth; Emily J. Southall; Alan J. Southward; Peter A. Henderson; Stephen J. Hawkins

2004-01-01

349

Response of the North American Corn Belt to Climatic Warming, CO sub 2.  

National Technical Information Service (NTIS)

The climate of the North American corn belt was characterized to estimate the effects of climatic change on that agricultural region. Heat and moisture characteristics of the current corn belt were identified and mapped based on a simulated climate for a ...

1983-01-01

350

Warming to a Redefinition of International Security: The Consolidation of a Norm Concerning Climate Change  

Microsoft Academic Search

The fundamental idea of this article is that the enormity and nature of the challenges created by climate change are redefining the understanding and definition of international security. The threats posed by climate change have become considered security threats, especially since 2007. I also argue that an international norm concerning climate change started emerging and became consolidated around the same

Denise Garcia

2010-01-01

351

Reducing Global Warming and Adapting to Climate Change: The Potential of Organic Agriculture  

Microsoft Academic Search

Climate change mitigation is urgent, and adaptation to climate change is crucial, particularly in agriculture, where food security is at stake. Agriculture, currently responsible for 20-30% of global greenhouse gas emissions (counting direct and indirect agricultural emissions), can however contribute to both climate change mitigation and adaptation. The main mitigation potential lies in the capacity of agricultural soils to sequester

Adrian Muller; Joergen Olesen; Laurence Smith; Joan Davis; Karolína Dytrtová; Andreas Gattinger; Nic Lampkin; Urs Niggli

2012-01-01

352

From Vegetation Zones to Climatypes: Effects of Climate Warming on Siberian Ecosystems  

Microsoft Academic Search

\\u000a Evidence for global warming over the past 200 years is overwhelming, based on both direct weather observation and indirect\\u000a physical and biological indicators such as retreating glaciers and snow\\/ice cover, increasing sea level, and longer growing\\u000a seasons (IPCC 2001, 2007). On the background of global warming at a rate of 0.6°C during the twentieth century (IPCC 2001),\\u000a the temperature increase

N. M. Tchebakova; G. E. Rehfeldt; E. I. Parfenova

353

Changes in alpine plant growth under future climate conditions  

Microsoft Academic Search

Alpine shrub- and grasslands are shaped by extreme climatic conditions such as a long-lasting snow cover and a short vegetation period. Such ecosystems are expected to be highly sensitive to global environmental change. Prolonged growing seasons and shifts in temperature and precipitation are likely to affect plant phenology and growth. In a unique experiment, climatology and plant growth was monitored

A. Rammig; T. Jonas; N. E. Zimmermann; C. Rixen

2009-01-01

354

Changes in alpine plant growth under future climate conditions  

Microsoft Academic Search

Alpine shrub- and grasslands are shaped by extreme climatic conditions such as a long-lasting snow cover and a short vegetation period. Such ecosystems are expected to be highly sensitive to global environmental change. Prolonged growing seasons and shifts in temperature and precipitation are likely to affect plant phenology and growth. In a unique experiment, climatology and plant growth was monitored

A. Rammig; T. Jonas; N. E. Zimmermann; C. Rixen

2010-01-01

355

Hydration during exercise in warm, humid conditions: effect of a caffeinated sports drink.  

PubMed

Caffeine is regarded as a diuretic despite evidence that hydration is not impaired with habitual ingestion. The purpose of this study was to determine whether a caffeinated sports drink impairs fluid delivery and hydration during exercise in warm, humid conditions (28.5 degrees C, 60% relative humidity). Sixteen cyclists completed 3 trials: placebo (P), carbohydrate-electrolyte (CE), and caffeinated (195 mg/L) sports drink (CAF+CE). Subjects cycled for 120 min at 60-75%VO2max followed by 15 min of maximal-effort cycling. Heart rate and rectal temperature were similar until the final 15 min, when these responses and exercise intensity were higher with CAF+CE than with CE and P. Sweat rate, urine output, plasma- volume losses, serum electrolytes, and blood deuterium-oxide accumulation were not different. Serum osmolality was higher with CAF+CE vs. P but not CE. The authors conclude that CAF+CE appears as rapidly in blood as CE and maintains hydration and sustains cardiovascular and thermoregulatory function as well as CE during exercise in a warm, humid environment. PMID:17507741

Millard-Stafford, Mindy L; Cureton, Kirk J; Wingo, Jonathan E; Trilk, Jennifer; Warren, Gordon L; Buyckx, Maxine

2007-04-01

356

Premonsoon aerosol characterization and radiative effects over the Indo-Gangetic Plains: Implications for regional climate warming  

NASA Astrophysics Data System (ADS)

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 Wm-2 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 ˜550 nm) with diurnal mean surface and top-of-atmosphere forcing values ranging from -11 to -79.8 Wm-2 and +1.4 to +12 Wm-2, 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 ˜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 ± 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.

2010-09-01

357

Experimental Warming and Precipitation Effects on Plant Community Composition, Productivity, Nutrient Availability, and Soil Respiration in Pacific Northwest Prairies along a Natural Climate Gradient  

NASA Astrophysics Data System (ADS)

Climate change effects on soil respiration and carbon stores in grasslands globally may have significant implications for future atmospheric carbon dioxide concentrations. Climate change may also may negatively impact native plant species and favor exotic species. We are experimentally increasing temperature by 3 degrees C and increasing precipitation by 25% above ambient in three upland prairie sites along a natural climate gradient from southwestern Oregon to central-western Washington to determine how future climate change will affect (i) plant community composition and the relative success of native versus introduced plant species and (ii) above- and belowground carbon and nutrient dynamics. Sixty plots (20 at each site) were restored by mowing, raking, and herbicide application followed by the sowing of the same 34 native grass and forb species in each plot. Differences in total cover, net primary productivity, and community composition were much greater among sites than among treatments within sites in both 2010--the establishment year, and 2011-the first full year of treatment. Strong successional dynamics occurred over the two years as competition intensified, but these were dependent on a site-treatment interaction, with lower native plant survival in heated plots because of competitive exclusion by exotic, invasive plants. A strong treatment - season interaction in canopy cover (as determined by canopy reflectance) also occurred, with heating causing greater cover during the wet season and lower cover during the dry season. This effect was strongest in the southernmost site which experiences earlier and more intense drought conditions. There were also strong site, treatment, and season interactions on nutrient availability as determined by cation-anion exchange resins. Heating increased nutrient availability in all but the northernmost site during the growing season, and that site also had much lower nutrient availability, but overall availability and site and treatment effects were less during the winter. Plant dynamics among the sites are likely strongly controlled by these differences in nutrient availability. In the winter, heating increased soil respiration, but this effect was lost as the sites warmed and dried during the growing season, with this switch in treatment effect occurring earlier in the spring in the southernmost site. Overall, we have observed many significant effects of the warming and precipitation treatments on plant and ecosystem dynamics, but these effects are often seasonally dependent and of lesser importance than strong differences among sites, driven by differences in soils and the pressure from invasive species. Our experiment shows the importance of placing climate change impacts on natural ecosystems within a context of local ecosystem controls.

Bridgham, S. D.; Pfeifer-Meister, L.; Tomaszewski, T.; Reynolds, L.; Goklany, M.; Wilson, H.; Johnson, B. R.

2011-12-01

358

Analyses of the warm season rainfall climatology of the northeastern US using regional climate model simulations and radar rainfall fields  

NASA Astrophysics Data System (ADS)

We examine the warm season (April-September) rainfall climatology of the northeastern US through analyses of high-resolution radar rainfall fields from the Hydro-NEXRAD system and regional climate model simulations using the weather research and forecasting (WRF) model. Analyses center on the 5-year period from 2003 to 2007 and the study area includes the New York-New Jersey metropolitan region covered by radar rainfall fields from the Fort Dix, NJ WSR-88D. The objective of this study is to develop and test tools for examining rainfall climatology, with a special focus on heavy rainfall. An additional emphasis is on rainfall climatology in regions of complex terrain, like the northeastern US, which is characterized by land-water boundaries, large heterogeneity in land use and cover, and mountainous terrain in the western portion of the region. We develop a 5-year record of warm season radar rainfall fields for the study region using the Hydro-NEXRAD system. We perform regional downscaling simulations for the 5-year study period using the WRF model. Radar rainfall fields are used to characterize the interannual, seasonal and diurnal variation of rainfall over the study region and to examine spatial heterogeneity of rainfall. Regional climate model simulations are characterized by a wet bias in the rainfall fields, with the largest bias in the high-elevation regions of the model domain. We show that model simulations capture broad features of the interannual, seasonal, and diurnal variation of rainfall. Model simulations do not capture spatial gradients in radar rainfall fields around the New York metropolitan region and land-water boundaries to the east. The model climatology of convective available potential energy (CAPE) is used to interpret the regional distribution of warm season rainfall and the seasonal and diurnal variability of rainfall. We use hydrologic and meteorological observations from July 2007 to examine the interactions of land surface processes and rainfall from a regional perspective.

Yeung, June K.; Smith, James A.; Villarini, Gabriele; Ntelekos, Alexandros A.; Baeck, Mary Lynn; Krajewski, Witold F.

2011-02-01

359

Climate warming and the decline of zooplankton in the California current  

SciTech Connect

Since 1951, the biomass of macrozooplankton in waters off southern California has decreased by 80 percent. During the same period, the surface layer warmed-by more than 1.5{degrees}C in some places-and the temperature differences across the thermocline increased. Increased stratification resulted in less lifting of the thermocline by wind-driven upwelling. A shallower source of upwelled waters provided less inorganic nutrient for new biological production and hence supported a smaller zooplankton population. Continued warming could lead to further decline of zooplankton. 10 refs., 5 figs.

Roemmich, D.; McGowan, J. [Univ. of California, San Diego, CA (United States)

1995-03-03

360

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

1999-02-01

361

Acclimation of photosynthesis and respiration to simulated climatic warming in northern and southern populations of Acer saccharum: laboratory and field evidence.  

PubMed

Physiological acclimation and genotypic adaptation to prevailing temperatures may influence forest responses to future climatic warming. We examined photosynthetic and respiratory responses of sugar maple (Acer saccharum Marsh.) from two portions of the species' range for evidence of both phenomena in a laboratory study with seedlings. A field study was also conducted to assess the impacts of temperature acclimation on saplings subjected to an imposed temperature manipulation (4 degrees C above ambient temperature). The two seedling populations exhibited more evidence of physiological acclimation to warming than of ecotypic adaptation, although respiration was less sensitive to short-term warming in the southern population than in the northern population. In both seedling populations, thermal compensation increased photosynthesis by 14% and decreased respiration by 10% in the warm-acclimated groups. Saplings growing in open-top field chambers at ambient temperature and 4 degrees C above ambient temperature showed evidence of temperature acclimation, but photosynthesis did not increase in response to the 4 degrees C warming. On the contrary, photosynthetic rates measured at the prevailing chamber temperature throughout three growing seasons were similar, or lower (12% lower on average) in saplings maintained at 4 degrees C above ambient temperature compared with saplings maintained at ambient temperature. However, the long-term photosynthetic temperature optimum for saplings in the field experiment was higher than it was for seedlings in either the 27 or the 31 degrees C growth chamber. Respiratory acclimation was also evident in the saplings in the field chambers. Saplings had similar rates of respiration in both temperature treatments, and respiration showed little dependence on prevailing temperature during the growing season. We conclude that photosynthesis and respiration in sugar maple have the potential for physiological acclimation to temperature, but exhibit a low degree of genetic adaptation. Some of the potential for acclimation to a 4 degrees C increase above a background of naturally fluctuating temperatures may be offset by differences in water relations, and, in the long term, may be obscured by the inherent variability in rates under field conditions. Nevertheless, physiologically based models should incorporate seasonal acclimation to temperature and permit ecotypic differences to influence model outcomes for those species with high genetic differentiation between regions. PMID:12651476

Gunderson, Carla A.; Norby, Richard J.; Wullschleger, Stan D.

2000-01-01

362

Justice in a Warming World: Global and Intergenerational Justice and Climate Change  

Microsoft Academic Search

Recent discussions on global climate change have brought to our attention the largely disruptive influence of human activity on the planet and its inhabitants. Moral philosophers have added to the discourse their concerns about the unprecedented environmental problem of global climate change which threatens, and increasingly so, human welfare and the stability of the planet. The circumstances should be of

Mazen Zehairi

2012-01-01

363

Global warming and biodiversity: Evidence of climate-linked amphibian declines in Italy  

Microsoft Academic Search

Amphibians are among the most endangered animals on Earth, and climatic shifts are among the hypothesized factors in their decline. We used spatial patterns of recent amphibian declines in Italy to test hypotheses pertaining to three potential, nonexclusive factors: climate change, habitat alteration, and high levels of incident solar radiation. This study was based on patterns of presence in a

Manuela D’Amen; Pierluigi Bombi

2009-01-01

364

CLIMATE WARMING AND THE CARBON CYCLE IN THE PERMAFROST ZONE OF THE FORMER SOVIET UNION  

EPA Science Inventory

The continuous permafrost zone of the former Soviet Union occupies 5% of the land surface area of the earth and stores a significant amount of carbon. limate warming could disrupt the balance between carbon (C) accumulation and decomposition processes within the permafrost zone. ...

365

Water-Vegetation Interaction in Mediterranean Climate Zones Under Global Warming  

Microsoft Academic Search

Water shortage controls biotic production over much of the land surface. Global warming will exacerbate water limitation in arid and semiarid areas, but high CO2 concentrations should increase plant water use efficiency; the net impact on vegetation productivity and water availability is uncertain. We analyzed the response of vegetation to historic and future (SRES A2) fossil CO2 emissions in the

N. Y. Krakauer; I. F. Fung

2006-01-01

366

Exceptional aerobic scope and cardiovascular performance of pink salmon (Oncorhynchus gorbuscha) may underlie resilience in a warming climate.  

PubMed

Little is known of the physiological mechanisms underlying the effects of climate change on animals, yet it is clear that some species appear more resilient than others. As pink salmon (Oncorhynchus gorbuscha) in British Columbia, Canada, have flourished in the current era of climate warming in contrast to other Pacific salmonids in the same watershed, this study investigated whether the continuing success of pink salmon may be linked with exceptional cardiorespiratory adaptations and thermal tolerance of adult fish during their spawning migration. Sex-specific differences existed in minimum and maximum oxygen consumption rates (M(O2,min) and M(O2,max), respectively) across the temperature range of 8 to 28°C, reflected in a higher aerobic scope (M(O2,max)-M(O2,min)) for males. Nevertheless, the aerobic scope of both sexes was optimal at 21°C (T(opt)) and was elevated across the entire temperature range in comparison with other Pacific salmonids. As T(opt) for aerobic scope of this pink salmon population is higher than in other Pacific salmonids, and historic river temperature data reveal that this population rarely encounters temperatures exceeding T(opt), these findings offer a physiological explanation for the continuing success of this species throughout the current climate-warming period. Despite this, declining cardiac output was evident above 17°C, and maximum attainable swimming speed was impaired above ?23°C, suggesting negative implications under prolonged thermal exposure. While forecasted summer river temperatures over the next century are likely to negatively impact all Pacific salmonids, we suggest that the cardiorespiratory capacity of pink salmon may confer a selective advantage over other species. PMID:21865520

Clark, Timothy D; Jeffries, Kenneth M; Hinch, Scott G; Farrell, Anthony P

2011-09-15

367

The role of water vapor feedback in unperturbed climate variability and global warming  

SciTech Connect

To understand the role of water vapor feedback in unperturbed surface temperature variability, a version of the Geophysical Fluid Dynamics Laboratory coupled ocean-atmosphere model is integrated for 1,000 yr in two configurations, one with water vapor feedback and one without. To understand the role of water vapor feedback in global warming, two 500-yr integrations were also performed in which CO{sub 2} was doubled in both model configurations. The final surface global warming in the model with water vapor feedback is 3.38 C, while in the one without it is only 1.05 C. However, the model`s water vapor feedback has a larger impact on surface warming in response to a doubling of CO{sub 2} than it does on internally generated, low-frequency, global-mean surface temperature anomalies. Water vapor feedback`s strength therefore depends on the type of temperature anomaly it affects. Finally, the authors compare the local and global-mean surface temperature time series from both unperturbed variability experiments to the observed record. The experiment without water vapor feedback does not have enough global-scale variability to reproduce the magnitude of the variability in the observed global-mean record, whether or not one removes the warming trend observed over the past century. In contrast, the amount of variability in the experiment with water vapor feedback is comparable to that of the global-mean record, provided the observed warming trend is removed. Thus, the authors are unable to simulate the observed levels of variability without water vapor feedback.

Hall, A. [Princeton Univ., NJ (United States). Atmospheric and Oceanic Sciences Program; Manabe, Syukuro [Geophysical Fluid Dynamics Lab., Princeton, NJ (United States)

1999-08-01

368

Agricultural pests under future climate conditions: downscaling of regional climate scenarios with a stochastic weather generator  

Microsoft Academic Search

As a consequence of current and projected climate change in temperate regions of Europe, agricultural pests and diseases are expected to occur more frequently and possibly to extend to previously unaffected regions. Given their economic and ecological relevance, detailed forecasting tools for various pests have been developed, which model the infestation depending on actual weather conditions. Assessing the future risk

M. Hirschi; S. Stöckli; M. Dubrovsky; C. Spirig; M. W. Rotach; P. Calanca; J. Samietz

2010-01-01

369

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

370

Agricultural pests under future climate conditions: downscaling of regional climate scenarios with a stochastic weather generator  

NASA Astrophysics Data System (ADS)

As a consequence of current and projected climate change in temperate regions of Europe, agricultural pests and diseases are expected to occur more frequently and possibly to extend to previously unaffected regions. Given their economic and ecological relevance, detailed forecasting tools for various pests have been developed, which model the infestation depending on actual weather conditions. Assessing the future risk of pest-related damages therefore requires future weather data at high temporal and spatial resolution. In particular, pest forecast models are often not based on screen temperature and precipitation alone (i.e., the most generally projected climate variables), but might require input variables such as soil temperature, in-canopy net radiation or leaf wetness. Here, we use a stochastic weather and a re-sampling procedure for producing site-specific hourly weather data from regional climate change scenarios for 2050 in Switzerland. The climate change scenarios were derived from multi-model projections and provide probabilistic information on future regional changes in temperature and precipitation. Hourly temperature, precipitation and radiation data were produced by first generating daily weather data for these climate scenarios and then using a nearest neighbor re-sampling approach for creating realistic diurnal cycles. These hourly weather time series were then used for modeling important phases in the lifecycle of codling moth, the major insect pest in apple orchards worldwide. First results indicate a shift in the occurrence and duration of phases relevant for pest disease control for projected as compared to current climate (e.g. the flight of the codling moth starts about ten days earlier in future climate), continuing an already observed trend towards more favorable conditions for this insect during the last 20 years.

Hirschi, M.; Stöckli, S.; Dubrovsky, M.; Spirig, C.; Rotach, M. W.; Calanca, P.; Samietz, J.

2010-09-01

371

Antarctic climate variability during the past few centuries based on ice cores from coastal Dronning Maud Land and its implications on climatic teleconnections and recent warming  

NASA Astrophysics Data System (ADS)

The role of Antarctic climate variables within the global system and its spatial and temporal complexity are still poorly understood due to the limited and very short periods of observational data collected over a few decades. In order to reconstruct the coastal Antarctic variability during the past five centuries with annual to sub-annual resolution, two firn/ice cores (62 and 65 m) from the central Dronning Maud Land region were studied for proxy parameters like stable isotope and dust records. While the IND-25/B5 provided high-resolution records of the past 100 years (1905-2005), the IND-22/B4 core represented the past ~470 years (1530-2002) of climate change. The IND-25/B5 ?18O record revealed a significant relation to the Southern Annular Mode (SAM), except during certain intervals (1918-1927, 1938-1947 & 1989-2005), when linkage to the El Niño Southern Oscillation (ENSO) was established through the in-phase relation between SAM and ENSO. However, on a decadal scale, a significant relationship between ?18O and SAM is observed that overrides the intermittent the influence of ENSO. Significant shifts in the deuterium excess record were also observed during periods of ENSO interaction. This may imply a change in moisture source during the periods of stronger ENSO teleconnections. The extended records of IND-22/B4 exhibited relatively more negative ?18O values during periods of reduced solar activity like the Dalton and Maunder Minima, suggesting influence of solar activity on Antarctic climate. The estimated surface air temperatures using the ?18O profiles of two ice cores revealed a significant warming by 0.6-1°C per century, with greatly enhanced warming during the past few decades (~0.4°C per decade).

Meloth, T.; Naik, S.; Laluraj, C. M.; Chaturvedi, A.; Ravindra, R.

2010-12-01

372

The transferability of hydrological models under nonstationary climatic conditions  

NASA Astrophysics Data System (ADS)

This paper investigates issues involved in calibrating hydrological models against observed data when the aim of the modelling is to predict future runoff under different climatic conditions. To achieve this objective, we tested two hydrological models, DWBM and SIMHYD, using data from 30 unimpaired catchments in Australia which had at least 60 yr of daily precipitation, potential evapotranspiration (PET), and streamflow data. Nash-Sutcliffe efficiency (NSE), modified index of agreement (d1) and water balance error (WBE) were used as performance criteria. We used a differential split-sample test to split up the data into 120 sub-periods and 4 different climatic sub-periods in order to assess how well the calibrated model could be transferred different periods. For each catchment, the models were calibrated for one sub-period and validated on the other three. Monte Carlo simulation was used to explore parameter stability compared to historic climatic variability. The chi-square test was used to measure the relationship between the distribution of the parameters and hydroclimatic variability. The results showed that the performance of the two hydrological models differed and depended on the model calibration. We found that if a hydrological model is set up to simulate runoff for a wet climate scenario then it should be calibrated on a wet segment of the historic record, and similarly a dry segment should be used for a dry climate scenario. The Monte Carlo simulation provides an effective and pragmatic approach to explore uncertainty and equifinality in hydrological model parameters. Some parameters of the hydrological models are shown to be significantly more sensitive to the choice of calibration periods. Our findings support the idea that when using conceptual hydrological models to assess future climate change impacts, a differential split-sample test and Monte Carlo simulation should be used to quantify uncertainties due to parameter instability and non-uniqueness.

Li, C. Z.; Zhang, L.; Wang, H.; Zhang, Y. Q.; Yu, F. L.; Yan, D. H.

2012-04-01

373

Global flood risks under changing climate and socioeconomic conditions  

NASA Astrophysics Data System (ADS)

Worldwide major flood events result in both economic losses and large numbers of casualties. Recent global scale studies indicate that in many regions of the world discharge extremes are likely to increase under changing climate conditions. However, few studies have so far examined how these changes in climate conditions may affect flood risk (defined here as the probability of a flood multiplied by the consequences). In the current study we investigate the impacts of changing climate and socioeconomic conditions on flood extents and depths, and also assess the potential impacts on flood risk. The study is conducted on a global scale, thereby indicating in which regions of the world flood risk is likely to change most. To assess global food risk under changing conditions, we combined socio-economic data from the Integrated Model to Assess the Global Environment (IMAGE) framework of the Netherlands Environmental Assessment Agency (PBL) with high resolution maps of inundation depth (1 km). To this end, projections from a number of GCMs were bias-corrected and used to force the global hydrological model PCR-GLOBWB which simulates (amongst other variables) global maps with daily flood volumes on a 0.5 degree resolution. These time series were used to derive flood volume maps for multiple return periods, which were downscaled to inundation depth maps at 1 km resolution using a 1 km resolution DEM. Finally, these high resolution flood maps were combined with spatial datasets on future GDP and population density from the IMAGE model. Results are presented on both the global scale and at the country level. We believe that the obtained flood extend and flood risk maps can assist development agencies in planning climate adaptation investments that aim to reduce flood risks.

Sperna Weiland, Frederiek; Ward, Philip; Bouwman, Arno; Ligtvoet, Willem; van Beek, Rens; Winsemius, Hessel

2013-04-01

374

Deglacial Warming in the Gulf of Mexico Preceded Laurentide Ice Sheet Meltwater Input: Implications for Tropical Climate Forcing  

NASA Astrophysics Data System (ADS)

As part of the Western Hemisphere Warm Pool (WHWP), the Gulf of Mexico is an important source of heat and moisture to the North American continent and the higher latitudes. Orca Basin on the Louisiana slope in the northern Gulf of Mexico is ideally located to record deglacial WHWP sea-surface temperature (SST) warming in relation to meltwater input from the Laurentide Ice Sheet (LIS). Paired ?18O and Mg/Ca data on planktic foraminifera (Globigerinoides ruber, white variety) from cores EN32-PC4 and -PC6 are used to separate deglacial changes in SST and ?18Oseawater due to low-salinity meltwater. In core EN32-PC4, Mg-SST increases from near full-glacial values of about 24°C at ca. 15 ka 14C to >28°C at ca. 12.8 ka 14C, including a sharp increase of >3°C from 14.2-13.3 ka 14C. This warming clearly precedes the peak of meltwater input (minimum Gs. ruber ?18O) by nearly 2 k.y. Furthermore, Mg-SST and global ?18Oseawater changes can be subtracted from Gs. ruber ?18O to isolate the influence of meltwater (ice-volume corrected ?18Oseawater), which can be interpreted in terms of salinity variations. This exercise indicates a peak in meltwater input at 12 ka 14C, close to the timing of meltwater pulse 1A. If confirmed in EN32-PC6, these results suggest that (1) subtropical deglacial SST warming preceded LIS decay, and (2) the origin of sea-level rise during mwp-1A was primarily meltwater derived from the LIS. Extending paired Mg-SST and ?18O data on Gs. ruber into Marine Isotope Stage (MIS) 3 further illuminates the phasing of WHWP changes relative to high-latitude climate variability. Preliminary results indicate significant SST variability that can be correlated to Dansgaard-Oeschger events of the Greenland ice core records. In addition, ?18O data on Gs. ruber (pink variety) indicate at least one interval of significant meltwater input in mid-MIS 3. Our continuing work will test the hypothesis that the tropical/subtropical Atlantic is an important driver of regional to global climate change.

Flower, B. P.; Hastings, D. W.; Hill, H. W.; Hollander, D. J.; Lodico, J.; Quinn, T. M.

2002-12-01

375

Regional climatic warming drives long-term community changes of British marine fish.  

PubMed Central

Climatic change has been implicated as the cause of abundance fluctuations in marine fish populations worldwide, but the effects on whole communities are poorly understood. We examined the effects of regional climatic change on two fish assemblages using independent datasets from inshore marine (English Channel, 1913-2002) and estuarine environments (Bristol Channel, 1981-2001). Our results show that climatic change has had dramatic effects on community composition. Each assemblage contained a subset of dominant species whose abundances were strongly linked to annual mean sea-surface temperature. Species' latitudinal ranges were not good predictors of species-level responses, however, and the same species did not show congruent trends between sites. This suggests that within a region, populations of the same species may respond differently to climatic change, possibly owing to additional local environmental determinants, interspecific ecological interactions and dispersal capacity. This will make species-level responses difficult to predict within geographically differentiated communities.

Genner, Martin J.; Sims, David W.; Wearmouth, Victoria J.; Southall, Emily J.; Southward, Alan J.; Henderson, Peter A.; Hawkins, Stephen J.

2004-01-01

376

Cloud tuning in a coupled climate model: Impact on 20th century warming  

NASA Astrophysics Data System (ADS)

Climate models incorporate a number of adjustable parameters in their cloud formulations. They arise from uncertainties in cloud processes. These parameters are tuned to achieve a desired radiation balance and to best reproduce the observed climate. A given radiation balance can be achieved by multiple combinations of parameters. We investigate the impact of cloud tuning in the CMIP5 GFDL CM3 coupled climate model by constructing two alternate configurations. They achieve the desired radiation balance using different, but plausible, combinations of parameters. The present-day climate is nearly indistinguishable among all configurations. However, the magnitude of the aerosol indirect effects differs by as much as 1.2 Wm - 2, resulting in significantly different temperature evolution over the 20th century.

Golaz, J.-C.; Golaz, Jean-Christophe; Levy, Hiram

2013-05-01

377

Potential climate change effects on warm-season livestock production in the Great Plains  

Microsoft Academic Search

Projected production responses were derived for confined swine and beef and for milk-producing dairy cattle based on climate\\u000a change projections in daily ambient temperature. Milk production from dairy cattle and the number of days to grow swine and\\u000a beef cattle were simulated. Values were obtained for three central United States transects and three climate scenarios which\\u000a were based on projected

Terry L. Mader; Katrina L. Frank; John A. Harrington Jr; G. Leroy Hahn; John A. Nienaber

2009-01-01

378

Deglacial abrupt climate change in the Atlantic Warm Pool: A Gulf of Mexico perspective  

Microsoft Academic Search

During the last deglaciation, Greenland ice core and North Atlantic sediment records exhibit multiple abrupt climate events including the Younger Dryas cold episode (12.9–11.7 ka). However, evidence for the presence of the Younger Dryas in the Gulf of Mexico (GOM) and the relationship between GOM sea surface temperature (SST) and high-latitude climate change is less clear. We present new Mg\\/Ca-SST

Carlie Williams; Benjamin P. Flower; David W. Hastings; Thomas P. Guilderson; Kelly A. Quinn; Ethan A. Goddard

2010-01-01

379

Mode shift in the Indian Ocean climate under global warming stress  

NASA Astrophysics Data System (ADS)

A 115-year coral record from Kenya has been found to preserve the history of rainfall anomalies in East Africa in relation to global warming-induced Indian Ocean Dipole (IOD) variability. The coral IOD index demonstrates a dominantly decadal periodicity in the early part of the 20th century. This low-frequency IOD occurred more frequently before 1924 with mostly quasi-biennial ranging from 18 months to 3 years events since 1960. The mode shift has also coincided with an intensified coupling with Indian summer monsoon rainfall. We suggest that a warming of the western Indian Ocean, which has attenuated and replaced the El Niño/Southern Oscillation effect over the Indian Ocean, has driven the observed shift.

Nakamura, Nobuko; Kayanne, Hajime; Iijima, Hiroko; McClanahan, Timothy R.; Behera, Swadhin K.; Yamagata, Toshio

2009-12-01

380

Global warming in a coupled climate model including oceanic eddy-induced advection  

NASA Astrophysics Data System (ADS)

The Gent and McWilliams (GM) parameterization for large-scale water transport caused by mesoscale oceanic eddies is introduced into the oceanic component of a global coupled ocean-atmosphere model. Parallel simulations with and without the GM scheme are performed to examine the effect of this parameterization on model behavior under constant atmospheric CO2 and on the model response to increasing CO2. The control (constant CO2) runs show substantial differences in the oceanic stratification and extent of convection, similar to differences found previously using uncoupled ocean models. The transient (increasing CO2) runs show moderate differences in the rate of oceanic heat sequestration (less in the GM case), as expected based on passive tracer uptake studies. However, the surface warming is weaker in the GM case, especially over the Southern Ocean, which is contrary to some recent supposition. Reasons for the reduced warming in the GM case are discussed.

Hirst, Anthony C.; Gordon, Hal B.; O'Farrell, Siobhan P.

381

The warm Cretaceous climate: Role of the long-term carbon cycle  

SciTech Connect

An annual energy-balance model is coupled to a steady state formulation of the long-term CO{sub 2} cycle to investigate the possible sources of the global warming at the Cretaceous. It is found that paleogeography solely is an insufficient factor but that the different latitudinal distribution of continental masses 100 My ago influenced the CO{sub 2} cycle and favored a larger content of the atmospheric CO{sub 2} level. A larger rate of tectonic activity and the possible influence of the vegetation in a CO{sub 2} richer atmosphere provide further sources of atmospheric carbon dioxide increase. The combination of these factors, together with a more vigorous poleward heat transport, provides CO{sub 2} levels 5 to 15 times larger than today and a global surface warming within the 6-12C estimated from paleoindicators.

Gerard, J.C.; Dols, V. (Universite de Liege (Belgium))

1990-09-01

382

Climatic prospects in the case of an extended, CO2-induced warming  

Microsoft Academic Search

The global climatological consequences of CO2-induced warming of 4-5 C are discussed in a review of recent theooretical models. At a critical CO2 threshold of 662 ppm + or - 10-15 percent, the partial disintegration of the ice sheet in western Antarctica accompanied by a rise of 5-7 m in sea level and\\/or the disappearance of the perennial Arctic sea

H. Flohn

1985-01-01

383

Mode shift in the Indian Ocean climate under global warming stress  

Microsoft Academic Search

A 115-year coral record from Kenya has been found to preserve the history of rainfall anomalies in East Africa in relation to global warming-induced Indian Ocean Dipole (IOD) variability. The coral IOD index demonstrates a dominantly decadal periodicity in the early part of the 20th century. This low-frequency IOD occurred more frequently before 1924 with mostly quasi-biennial ranging from 18

Nobuko Nakamura; Hajime Kayanne; Hiroko Iijima; Timothy R. McClanahan; Swadhin K. Behera; Toshio Yamagata

2009-01-01

384

The borehole temperature record of climate warming in the mid-continent of North America  

Microsoft Academic Search

Ground-surface temperature (GST) histories, determined from a carefully selected set of twenty-nine borehole temperature profiles, show a warming trend over the last century that increases systematically with latitude in the mid-continent of North America. Except one site in north Texas, the borehole locations lie within a 500 × 1000 km transect that extends from the Kansas-Nebraska border into southern Manitoba.

W. D. Gosnold; P. E. Todhunter; W. Schmidt

1997-01-01

385

Climatic Warming and the Decline of Zooplankton in the California Current  

Microsoft Academic Search

Since 1951, the biomass of macrozooplankton in waters off southern California has decreased by 80 percent. During the same period, the surface layer warmed-by more than 1.5^circC in some places-and the temperature difference across the thermocline increased. Increased stratification resulted in less lifting of the thermocline by wind-driven upwelling. A shallower source of upwelled waters provided less inorganic nutrient for

Dean Roemmich; John McGowan

1995-01-01

386

Climate warming and the decline of zooplankton in the California current  

Microsoft Academic Search

Since 1951, the biomass of macrozooplankton in waters off southern California has decreased by 80 percent. During the same period, the surface layer warmed-by more than 1.5°C in some places-and the temperature differences across the thermocline increased. Increased stratification resulted in less lifting of the thermocline by wind-driven upwelling. A shallower source of upwelled waters provided less inorganic nutrient for

D. Roemmich; J. McGowan

1995-01-01