THE 2-STEP SHAPE AND TIMING OF THE LAST DEGLACIATION IN ANTARCTICA

The two-step character of the last deglaciation is well recognized in Western Europe, in Greenland and in the North Atlantic. For example, i n Greenland, a gradual temperature decrease started at the Bolling (B) around 14.5 ky BP, spanned through the Allerod (A) and was followed b y the cold Younger Dryas (YD) event which terminated abruptly around 1 1.5 ky BP. Recent results suggest that this BA/YD sequence may have ex tended throughout all the Northern Hemisphere but the evidence of a la te transition cooling is still poor for the Southern Hemisphere. Here we present a detailed isotopic record analyzed in a new ice core drill ed at Dome B in East Antarctica that fully demonstrates the existence of an Antarctic cold reversal (ACR), These results suggest that the tw o-step shape of the last deglaciation has a worldwide character but th ey also point to noticeable interhemispheric differences, Thus, the co ldest part of the ACR, which shows a temperature drop about three time s weaker than that recorded during the YD in Greenland, may have prece ded the YD. Antarctica did not experienced abrupt changes and the two warming periods started there before they started in Greenland. The li nks between Southern and Northern Hemisphere climates throughout this period are discussed in the light of additional information derived fr om the Antarctic dust record.