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abstracts
Forcing of deglacial climate change and implications for greenhouse warming
Jeremy Shakun
Understanding how the climate system responds to forcings is critical to a complete theory of past changes in the earth’s climate as well as predicting the magnitude of future global warming. For example, climate models exhibit a considerable range in climate sensitivity, or the equilibrium response of global temperature to a doubling of atmospheric CO2 and empirical approaches have so far been unable to significantly reduce this uncertainty. The termination of the most recent ice age provides what is perhaps the best opportunity to address this issue as the climate forcings and response were very large and are relatively well-constrained by geological records. Here, I show that the dominant mode of global temperature variability during the last deglaciation was strongly related to rising greenhouse gas concentrations, while ocean circulation played a secondary role in driving climate change. Quantifying the temperature response to greenhouse forcing during this time suggests climate sensitivity is at or above the upper end of the Intergovernmental Panel on Climate Change’s best estimate. Thus, anthropogenic warming may be greater than has been generally expected.
Jeremy Shakun, Department of Geosciences, Oregon State University,104 Wilkinson Hall, Corvallis, OR 97331, United States, shakunj@geo.oregonstate.edu
Session: F1: Climate Forcings
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