A suite of simulations, done with a new high-resolution climate model (CM2.5) developed at GFDL, were used to study the observed long-term decline of winter rainfall over parts of southern Australia. In response to anthropogenic increases in greenhouse gases and reduction in stratospheric ozone, the model is able to capture many aspects of the observed drying, especially over southwest Australia. The model projects a continued decline in winter rainfall throughout the rest of the 21st century, with significant implications for regional water resources.
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GFDL Research Highlights
The insensitivity of the global climate response once emissions cease in simplified coupled climate models has been used to argue for lack of committed warming based on past carbon emissions. Additional studies have also demonstrated that the cessation of carbon emissions results in a stabilization or decrease of global mean surface air temperature. Such studies generally assume either a 1%/year increase or an instantaneous doubling/quadrupling of atmospheric CO2.
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The rapid change in summer Arctic sea ice could have significant large scale climatic, ecological, and economic impacts. Understanding the mechanisms for the recent rapid decline in summer Arctic sea ice will help to predict future changes in summer Arctic sea ice and associated climatic, ecological, and economic impacts.
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May 14th, 2014 - The Poleward Migration of the Location of Tropical Cyclone Maximum Intensity
Tropical cyclones (TCs), including hurricanes and typhoons, are a major hazard around the globe, including North America. TCs have exhibited variability and change on a variety of timescales, including multi-decadal changes.
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The impact of the late 20th century changes of anthropogenic aerosols from local (i.e., South Asia) and remote (i.e., outside South Asia) sources on the South Asian summer monsoon is a rather unexplored topic. It has important implications for strategies to control regional pollution and understand its effect in climate. GFDL scientists investigated the impact of this change in aerosols on the South Asian monsoon. This work provides new insights into the pathway by which global anthropogenic aerosols affect long-term variations of the monsoon hydroclimate, which is still uncertain and largely debated in the scientific community.
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February 14th, 2014 - Changing Ocean may Challenge Atlantic Cod
This study uses climate projections from GFDL’s Earth system model (ESM2.1) to force an individual-based model for the larval stages of North Atlantic Cod at each of 5 cod spawning sites across the North Atlantic. The behavioral and physiological state of thousands of cod larvae is modeled in response to ESM projected physical and biological changes. The ESM-IBM coupling provides a unique means of exploring the mechanistic response of cod larvae to climate forcing.
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February 6th, 2014 - Solving the mystery of Hawaiian ozone changes
A potent greenhouse gas and biological irritant, ozone near the Earth surface is also a health-damaging air pollutant, regulated by the U.S. Environmental Protection Agency. Shifts in atmospheric circulation have caused Asian ozone pollution reaching Hawaii to rise unexpectedly in autumn since mid-1990s, according to this study. The findings, published in Nature Geoscience, imply that decade-long variability in climate must be considered when attributing observed ozone changes to human-induced trends in precursor emissions.
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This study advances our understanding of the physical processes controlling the dynamics of ice streams – pathways for ice discharge from the interior of ice sheets to surrounding oceans – and the leading source of uncertainty in projections of global sea level rise in the 21st century.
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The authors compared observations to model results, using 23 different CMIP5 models to simulate internal climate variability and the response to anthropogenic and natural forcing. The models were used to investigate the causes of the unusual warmth during March-May 2012 that occurred over the eastern U.S. The 20thcentury warming trend that was observed in this region is consistent with the CMIP5 multi-model ensemble results of All-Forcing runs but not consistent with model runs that did not include external forcing. The long-term trends in the models are predominantly due to anthropogenic forcing. Therefore, we interpret the extreme warmth of March-May 2012 over the eastern U.S. as very likely attributable, at least in part, to anthropogenic forcing. The CMIP5 models’ central estimate of the contribution of anthropogenic forcing to the March-May 2012 anomaly is about 35% in terms of magnitude. Moreover, the model results suggest that the risk of a warm anomaly in the eastern U.S. as large as that seen in March-May 2012 has now increased by about a factor of 10 due to long-term climate warming—primarily anthropogenic in origin.
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Planktonic food web dynamics shape biogeochemical cycles and global patterns of ocean productivity across trophic levels. Primary production alone, for example, is a poor predictor of cross-ecosystem differences in fisheries yields. Predictive capability improves only after consideration of factors such as the number and efficiency of trophic links separating phytoplankton and fish. Limited representation and validation of planktonic food web dynamics within the present generation of Earth System Models limits both their resolution of biogeochemical processes and their utility for assessing climate impacts on living marine resources.
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