Sensitivity of the Northern Hemisphere climate of the Last Glacial Maximum to sea surface temperatures

The role of prescribing sea surface temperature in paleoclimate atmospheric simulations has been investigated by comparing Last Glacial Maximum AGCMs experiments using different SSTs data sets as well as coupled atmosphere/oceanic mixed layer models. Changes in the SSTs and sea-ice margin generate different patterns of zonal asymmetries in the atmospheric circulation that are responsible for reorganisation of heat and moisture transport, leading to important variations of Northern Hemisphere regional climates, particularly in winter. Additional sensitivity experiments have been carried out to isolate the individual role of North Pacific and North Atlantic SSTs anomalies. We found that changes in North Pacific SSTs have a much stronger impact over all the northern continental surfaces, including Europe and Siberia, than changes in the North Atlantic SSTs. As these SSTs anomalies are of the order of the typical errors generated by coupled ocean-atmosphere models, this suggests that these more complete models will likely still have problems in simulating the regional climate change at the LGM. Received: 11 October 1999 / Accepted: 9 June 2000