HR: 1340h
AN: U43A-0856    [Abstracts]
TI: Sensitivity of Arctic Sea Ice to Global Warming Forcing in Observations and Climate Model Simulations
AU: * Zhang, X
EM: xdz@iarc.uaf.edu
AF: International Arctic Research Center, University of Alaska Fairbanks, 930 Koyukuk Dr., Fairbanks, AK 99775, United States
AB: Response of Arctic sea ice coverage to global warming forcing exhibits a large diversity across climate models and across climate model ensemble members, as shown in our recent study for the IPCC AR4. This constitutes a major source of uncertainty in estimating climate sensitivity. Arctic sea ice, as an essential component of climate system, greatly impacts global energy balance due to its high radiative reflectance and associated albedo feedback. Extension and retreat of sea ice coverage accordingly contribute to variability of and change in global mean surface air temperature. In particular, Arctic sea ice coverage shrinks rapidly in recent decades and this shrinkage would be accelerated under global warming scenario. This would lead to an intensification of albedo feedback and, in turn, a further amplification of surface air temperature increase over the Arctic region. In order to improve understanding of the origin of the above-mentioned uncertainty, we analyzed sensitivity of Arctic sea ice cover to the change in surface air temperature in observations and in 20 IPCC AR4 climate models, including their multiple ensemble members for each model. The results show divergent sensitivity across models and even across ensemble members in the same model, with most of them differing from observations. Also, the sensitivity differs in climate change. Detailed and quantitative analysis from this study also helps better understanding and reducing uncertainty in assessment of climate change feedback processes and future climate change projections.
DE: 1620 Climate dynamics (0429, 3309)
DE: 1621 Cryospheric change (0776)
DE: 3305 Climate change and variability (1616, 1635, 3309, 4215, 4513)
DE: 4207 Arctic and Antarctic oceanography (9310, 9315)
DE: 4540 Ice mechanics and air/sea/ice exchange processes (0700, 0750, 0752, 0754)
SC: Union [U]
MN: 2007 Fall Meeting