HR: 08:30h
AN: C31B-03    [Abstracts]
TI: Amplified Arctic Warming and Ice-Albedo Feedback in the AR4 Climate Models
AU: * Winton, M
EM: Michael.Winton@noaa.gov
AF: GFDL/NOAA, P.O. Box 308 Princeton University, Princeton, NJ 08542 United States
AB: The role of ice-albedo feedback, as well of that of other feedbacks and forcings, in the amplified temperature response of the Arctic to increased CO2 is studied using diagnostics from 12 climate models participating in the IPCC fourth assessment report (AR4). At the time of CO2 doubling, these models have an Arctic (60N-90N) warming that is, on average, 1.9 times their global warmings. Applying a zero-dimensional energy balance model to the Arctic and global regions, an expression is derived that gives the Arctic amplification as a function of forcings and feedbacks in the two regions. The ice-albedo feedback, the longwave feedback and the net top-of-atmosphere forcing (equal to the sum of the surface flux and the atmospheric heat flux convergence) contribute to the Arctic amplification. The CO2 forcing and the non-ice-albedo shortwave feedback oppose Arctic amplification. Possible reasons for the differences in Arctic and global feedbacks and forcings as well as their intermodel variations are discussed.
DE: 0736 Snow (1827, 1863)
DE: 0738 Ice (1863)
DE: 1620 Climate dynamics (0429, 3309)
DE: 1626 Global climate models (3337, 4928)
DE: 1637 Regional climate change
SC: Cryosphere [C]
MN: Fall Meeting 2005