Model Projections of an Imminent Transition to a More Arid Climate in
01 Jan 2007-
TL;DR: There is a broad consensus among climate models that this region will dry in the 21st century and that the transition to a more arid climate should already be under way, and the levels of aridity of the recent multiyear drought or the Dust Bowl and the 1950s droughts will become the new climatology of the American Southwest within a time frame of years to decades.
About: The article was published on 2007-01-01 and is currently open access. It has received 1922 citations till now.
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United States Geological Survey1, University of Arizona2, University of Batna3, Oregon State University4, Los Alamos National Laboratory5, Centre national de la recherche scientifique6, Swiss Federal Institute for Forest, Snow and Landscape Research7, Natural Resources Canada8, University of California, Berkeley9, University of Granada10, Northern Research Institute11, Forest Research Institute12, Food and Agriculture Organization13, University of Montana14, Northern Arizona University15
TL;DR: In this paper, the authors present the first global assessment of recent tree mortality attributed to drought and heat stress and identify key information gaps and scientific uncertainties that currently hinder our ability to predict tree mortality in response to climate change and emphasizes the need for a globally coordinated observation system.
5,811 citations
Cites background from "Model Projections of an Imminent Tr..."
...…likely to include further increases in mean temperature (about 2–4 8C globally) with significant drying in some regions (Christensen et al., 2007; Seager et al., 2007), as well as increases in frequency and severity of extreme droughts, hot extremes, and heat waves (IPCC, 2007a; Sterl et al.,…...
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...…reconstructions of drought in Algeria show that this early 2000s dry period was the most severe drought since at least the middle of the 15th century (Touchan et al., 2008), consistent with climate change projections for a trend of increasing aridity in this region (Seager et al., 2007)....
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TL;DR: In this paper, the authors look at observations and model projections from 1923 to 2010, to test the ability of models to predict future drought conditions, which inspires confidence in their projections of drought.
Abstract: Historical records show increased aridity over many land areas since 1950. This study looks at observations and model projections from 1923 to 2010, to test the ability of models to predict future drought conditions. Models are able to capture the greenhouse-gas forcing and El Nino–Southern Oscillation mode for historical periods, which inspires confidence in their projections of drought.
3,385 citations
TL;DR: A hydraulically based theory considering carbon balance and insect resistance that allowed development and examination of hypotheses regarding survival and mortality was developed, and incorporating this hydraulic framework may be effective for modeling plant survival andortality under future climate conditions.
Abstract: Summary Severe droughts have been associated with regional-scale forest mortality worldwide. Climate change is expected to exacerbate regional mortality events; however, pre- diction remains difficult because the physiological mechanisms underlying drought survival and mortality are poorly understood. We developed a hydraulically based theory considering carbon balance and insect resistance that allowed development and examination of hypotheses regarding survival and mortality. Multiple mechanisms may cause mortality during drought. A common mechanism for plants with isohydric
3,302 citations
Cites background from "Model Projections of an Imminent Tr..."
...Climate models generally agree that over the next 50 yr the Earth’s surface temperatures will increase along with shifts in precipitation that result in greater drought severity and frequency (Cook et al., 2004; IPCC, 2007; Seager et al., 2007)....
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...This simple exercise assumes no physiological acclimation, but is conservative relative to climate predictions for the next century (IPCC, 2007; Seager et al., 2007)....
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TL;DR: Wiley et al. as mentioned in this paper reviewed recent literature on the last millennium, followed by an update on global aridity changes from 1950 to 2008, and presented future aridity is presented based on recent studies and their analysis of model simulations.
Abstract: This article reviews recent literature on drought of the last millennium, followed by an update on global aridity changes from 1950 to 2008. Projected future aridity is presented based on recent studies and our analysis of model simulations. Dry periods lasting for years to decades have occurred many times during the last millennium over, for example, North America, West Africa, and East Asia. These droughts were likely triggered by anomalous tropical sea surface temperatures (SSTs), with La Ni˜ na-like SST anomalies leading to drought in North America, and El-Ni˜ no-like SSTs causing drought in East China. Over Africa, the southward shift of the warmest SSTs in the Atlantic and warming in the Indian Ocean are responsible for the recent Sahel droughts. Local feedbacks may enhance and prolong drought. Global aridity has increased substantially since the 1970s due to recent drying over Africa, southern Europe, East and South Asia, and eastern Australia. Although El Ni˜ no-Southern Oscillation (ENSO), tropical Atlantic SSTs, and Asian monsoons have played a large role in the recent drying, recent warming has increased atmospheric moisture demand and likely altered atmospheric circulation patterns, both contributing to the drying. Climate models project increased aridity in the 21 st century over most of Africa, southern Europe and the Middle East, most of the Americas, Australia, and Southeast Asia. Regions like the United States have avoided prolonged droughts during the last 50 years due to natural climate variations, but might see persistent droughts in the next 20–50 years. Future efforts to predict drought will depend on models’ ability to predict tropical SSTs. 2010 JohnWiley &Sons,Ltd.WIREs Clim Change2010 DOI:10.1002/wcc.81
2,651 citations
TL;DR: The climate change that takes place due to increases in carbon dioxide concentration is largely irreversible for 1,000 years after emissions stop, showing that thermal expansion of the warming ocean provides a conservative lower limit to irreversible global average sea level rise.
Abstract: The severity of damaging human-induced climate change depends not only on the magnitude of the change but also on the potential for irreversibility. This paper shows that the climate change that takes place due to increases in carbon dioxide concentration is largely irreversible for 1,000 years after emissions stop. Following cessation of emissions, removal of atmospheric carbon dioxide decreases radiative forcing, but is largely compensated by slower loss of heat to the ocean, so that atmospheric temperatures do not drop significantly for at least 1,000 years. Among illustrative irreversible impacts that should be expected if atmospheric carbon dioxide concentrations increase from current levels near 385 parts per million by volume (ppmv) to a peak of 450–600 ppmv over the coming century are irreversible dry-season rainfall reductions in several regions comparable to those of the “dust bowl” era and inexorable sea level rise. Thermal expansion of the warming ocean provides a conservative lower limit to irreversible global average sea level rise of at least 0.4–1.0 m if 21st century CO2 concentrations exceed 600 ppmv and 0.6–1.9 m for peak CO2 concentrations exceeding ≈1,000 ppmv. Additional contributions from glaciers and ice sheet contributions to future sea level rise are uncertain but may equal or exceed several meters over the next millennium or longer.
2,604 citations
References
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TL;DR: In this paper, the authors examined some aspects of the hydrological cycle that are robust across the models, including the decrease in convective mass fluxes, the increase in horizontal moisture transport, the associated enhancement of the pattern of evaporation minus precipitation and its temporal variance, and decrease in the horizontal sensible heat transport in the extratropics.
Abstract: Using the climate change experiments generated for the Fourth Assessment of the Intergovernmental Panel on Climate Change, this study examines some aspects of the changes in the hydrological cycle that are robust across the models. These responses include the decrease in convective mass fluxes, the increase in horizontal moisture transport, the associated enhancement of the pattern of evaporation minus precipitation and its temporal variance, and the decrease in the horizontal sensible heat transport in the extratropics. A surprising finding is that a robust decrease in extratropical sensible heat transport is found only in the equilibrium climate response, as estimated in slab ocean responses to the doubling of CO2, and not in transient climate change scenarios. All of these robust responses are consequences of the increase in lower-tropospheric water vapor.
3,811 citations
01 Jul 2000
TL;DR: Nakicenovic, N., Alcamo, J., Davis, G., Vries, B. van; Victor, N.; Zhou, D. de; Fenhann, J.; Gaffin, S.; Gregory, K.; Grubler, A.; Jung, T. La; Michaelis, L.; Mori, S; Morita, T.; Pepper, W.; Pitcher, H.; Price, L., Riahi, K; Rogner, H-H.; Sankovski, A; Schlesinger, M.; Shuk
Abstract: Author(s): Nakicenovic, N.; Alcamo, J.; Davis, G.; Vries, B. de; Fenhann, J.; Gaffin, S.; Gregory, K.; Grubler, A.; Jung, T.Y.; Kram, T.; Rovere, E.L. La; Michaelis, L.; Mori, S.; Morita, T.; Pepper, W.; Pitcher, H.; Price, L.; Riahi, K.; Roehrl, A.; Rogner, H-H.; Sankovski, A.; Schlesinger, M.; Shukla, P.; Smith, S.; Swart, R.; Rooijen, S. van; Victor, N.; Zhou, D.
3,431 citations
TL;DR: Using gridded drought reconstructions that cover most of the western United States over the past 1200 years, it is shown that this drought pales in comparison to an earlier period of elevated aridity and epic drought in AD 900 to 1300, an interval broadly consistent with the Medieval Warm Period.
Abstract: The western United States is experiencing a severe multiyear drought that is unprecedented in some hydroclimatic records. Using gridded drought reconstructions that cover most of the western United States over the past 1200 years, we show that this drought pales in comparison to an earlier period of elevated aridity and epic drought in AD 900 to 1300, an interval broadly consistent with the Medieval Warm Period. If elevated aridity in the western United States is a natural response to climate warming, then any trend toward warmer temperatures in the future could lead to a serious long-term increase in aridity over western North America.
1,524 citations
1,306 citations
TL;DR: In this article, a consistent poleward and upward shift and intensification of the storm tracks is found in an ensemble of 21st century climate simulations performed by 15 coupled climate models.
Abstract: [1] A consistent poleward and upward shift and intensification of the storm tracks is found in an ensemble of 21st century climate simulations performed by 15 coupled climate models. The shift of the storm tracks is accompanied by a poleward shift and upward expansion of the midlatitude baroclinic regions associated with enhanced warming in the tropical upper troposphere and increased tropopause height. The poleward shift in baroclinicity is augmented in the Southern Hemisphere and partially offset in the Northern Hemisphere by changes in the surface meridional temperature gradient. The poleward shift of the storm tracks also tends to be accompanied by poleward shifts in surface wind stress and precipitation, and a shift towards the high index state of the annular modes. These results highlight the integral role that the storm tracks play in the climate system, and the importance of understanding how and why they will change in the future.
1,124 citations