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Climate Sensitivity Estimated from Temperature Reconstructions of the Last Glacial Maximum

Author:
Schmittner, Andreas, Urban, Nathan M., Shakun, Jeremy D., Mahowald, Natalie M., Clark, Peter U., Bartlein, Patrick J., Mix, Alan C., Rosell-Melé, Antoni
Source:
Science 2011 v.334 no.6061 pp. 1385-1388
ISSN:
0036-8075
Subject:
carbon, carbon dioxide, climate, climate change, climate models, emissions, simulation models, surface temperature, uncertainty
Abstract:
Assessing the impact of future anthropogenic carbon emissions is currently impeded by uncertainties in our knowledge of equilibrium climate sensitivity to atmospheric carbon dioxide doubling. Previous studies suggest 3 kelvin (K) as the best estimate, 2 to 4.5 K as the 66% probability range, and nonzero probabilities for much higher values, the latter implying a small chance of high-impact climate changes that would be difficult to avoid. Here, combining extensive sea and land surface temperature reconstructions from the Last Glacial Maximum with climate model simulations, we estimate a lower median (2.3 K) and reduced uncertainty (1.7 to 2.6 K as the 66% probability range, which can be widened using alternate assumptions or data subsets). Assuming that paleoclimatic constraints apply to the future, as predicted by our model, these results imply a lower probability of imminent extreme climatic change than previously thought.
Agid:
174555