Apparent Climate Sensitivity to Changes in Global Radiative Forcing: Patterns from the Last Deglaciation

A G Lapenis (Department of Geography and Planning and Department of Earth and Atmospheric Sinces, State University of New York at Albany, Albany, NY 12222; ph. 518-442-4586; fax 518-442-4494; Internet: alapenis@csc.albany.edu); H S Kheshgi (Exxon Research and Engineering Company, Annandale, NJ 08801; ph. 908-730-2531; fax 908-730-3301; Internet: hskhesh@erenj.com)

The asynchronous behavior of the main components of global radiative forcing during the last deglaciation is used to extract signals of these forcings from paleotemperature records from seventeen deep-sea cores along a N-S transect of the Atlantic Ocean, and two polar ice-core records. The response of surface temperature at all latitudes to decreases in global albedo was warming, reaching maxima at the Vostok (Antarctica) and GRIP (Greenland) sites. Forcing by increasing greenhouse gas concentrations combined with decreasing aerosols contributed to warming over the subtropical and subarctic oceanic gyres but cooling in the regions of Gulf Stream migration, West African upwelling, and Equatorial divergence. The pattern of temperature response to albedo forcing might be explained by the large changes of continental ice-sheets at high latitudes and migration of the sea ice border. The unusual cooling response at some regions to increases in greenhouse gases (and decreased aerosols) might be related to changes in meridional heat transport and rearrangement of deep oceanic circulation during the period of deglaciation.