HR: 14:10h
AN: C23B-03    [Abstracts]
TI: Permafrost and Climate Change: Here Today, Gone Tomorrow. A Coupled Climate Model Projection for the 20th and 21st Centuries.
AU: * Lawrence, D M
EM: dlawren@ucar.edu
AF: NCAR/CGD, P.O.Box 3000, Boulder, CO 80307 United States
AU: Slater, A G
EM: aslater@cires.colorado.edu
AF: CIRES/NSIDC, 449 UCB Univ. of Colorado, Boulder, CO 80309-0449 United States
AB: The representation of permafrost is examined in a fully coupled climate model, the Community Climate System Model version 3 (CCSM3). Permafrost and frozen ground is explicitly modeled in CCSM3, including interactive hydrology. We examine five member ensembles of CCSM3 integrations of 20th century climate as well as a number of IPCC SRES emission scenarios, including the A2 and commitment scenarios, that were conducted at NCAR in support of the fourth IPCC assessment report (AR4). Permafrost during the late 20th century is reasonably simulated in CCSM3, particularly in terms of the spatial extent which agrees well with observational estimates. Under the A2 emission scenario, permafrost, excluding the Antarctic and Greenland ice sheets, nearly completely disappears by the end of the 21st century. The impact of the dramatic loss of permafrost on surface fluxes of moisture and energy and on runoff to the Arctic Ocean is assessed. Among other impacts, total column soil water decreases, despite significantly stronger precipitation, due to enhanced drainage through the ice-free soil column. However, despite the fact that column soil water is reduced, there is more liquid soil water available for plants. The potentially positive climate feedback related to the likely increase in methane emissions from the newly active soil carbon pools will also be discussed.
DE: 0702 Permafrost (0475)
DE: 1626 Global climate models (3337, 4928)
DE: 1630 Impacts of global change (1225)
DE: 1655 Water cycles (1836)
SC: Cryosphere [C]
MN: Fall Meeting 2005