RESPONSE OF THE HIGH-LATITUDE NORTHERN-HEMISPHERE TO ORBITAL CLIMATE FORCING - EVIDENCE FROM THE NORDIC SEAS

Sediment cores from the Nordic (Greenland, Iceland, and Norwegian) sea s provide evidence that this area acts as an initial responder to the forcing effect of orbitally driven changes in insolation on the climat e system, as postulated by J. Imbrie et al. The deltaO-18 record of th e cores documents a widespread initial deglacial signal in the area be tween 15 and 13 ka, approximately 1000 yr before other deglacial signa ls from other parts of the Northern Hemisphere. An even earlier meltwa ter event has been dated to 16,090 +/-185 yr B.P. north of Iceland, at the initial rise of Northern Hemisphere insolation after the last gla cial maximum. During the period with lowered surface salinities, the N ordic seas were still cold. Reconstructions of the surface-water condi tions of the area show that, as the summer insolation values of the No rthern Hemisphere reached half of maximum values, a sea-ice-free corri dor opened along Norway at approximately 13.4 ka. Nearly contemporaneo us fluctuations of the polar front and the sea-surface temperatures wi th the insolation changes indicate that the Nordic seas are very sensi tive to insolation forcing, especially in regions close to the sea-ice margin. A decrease in sea-surface temperature and an increase in the areal extent of sea-ice cover since 7 ka indicate that the area is cur rently on the way to glacial conditions, supporting the predictions ma de earlier by J. Imbrie et al.