HR: 11:05h
AN: PP31D-04    [PDF]
TI: Milankovitch Forcing of Last Interglacial Warming of the Arctic
AU: * Otto-Bliesner, B L
EM: ottobli@ucar.edu
AF: National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80305 United States
AB: The Arctic climate response at the Last Interglacial (LIG) to Milankovitch changes of solar radiation is simulated using the fully coupled, non-flux corrected National Center for Atmospheric Research (NCAR) Community Climate System Model (CCSM2). The model is forced with trace gas concentrations and solar insolation changes for 130 ka. At 70§N, positive solar insolation anomalies at the top of the atmosphere occur from March-July with a maximum anomaly in excess of 70 W m-2 in May. The Arctic positive solar anomalies exceed those of the Holocene from 133-127 ka. During the LIG summers, the CCSM indicates warming up to 3§C over the Arctic Ocean and significant reduction in sea ice. The large positive solar anomalies in late spring-early summer allow sea ice to melt earlier resulting in enhanced summer warming of circum-Arctic ocean waters. Greenland warms by 1-5§C during the summer months with surface temperatures above freezing in the southern and coastal areas. The depth of snow remaining year-round decreases along the northern, western and southern edges of the Greenland ice cap. These simulations agree with proxy evidence of summer warming over the circum-Arctic land areas but underestimate the magnitude of warming over Siberia and southern Greenland. Feedbacks with vegetation and land ice, both fixed at present-day distributions in the LIG simulations, will need to be explored in additional simulations. Summer Arctic sea ice retreat and Greenland warming simulated by the CCSM for the LIG and increasing atmospheric CO2 levels will be compared.
DE: 1620 Climate dynamics (3309)
DE: 3309 Climatology (1620)
DE: 3344 Paleoclimatology
DE: 9315 Arctic region
DE: 9604 Cenozoic
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting