THE ONSET OF GIS-1/YOUNGER DRYAS IN THE CENTRAL SOUTH ATLANTIC

We have cored, sampled and analysed peat and lake sediments from Isla de los Estados, east of Terra del Fuego, and from Nightingale Island in the central South Atlantic, situated at the southern and northern limit of the Southern Hemisphere Westerlies (SHW), respectively. These localities are thus strategically situated to temporally map latitudinal changes of the SHW. While the Estados records span the last 16000 years, one of the Nightingale records covers the last 36000 years. Detailed radiocarbon measurements of the deposits have been combined with a set of multi-proxy analyses to analyse changes in wind strength and humidity, which are supposed to be closely related to the strength of the SHW. Temperature is another regionally important climatic forcing factor of the bipolar seesaw effect during the Last Termination, and we aim at deciphering the different climate signals. The onset of Greenland Interstadial 1/Younger Dryas is marked by a distinct cooling in the North Atlantic, but shows up in most of the Antarctic ice cores as a gradual warming after the Antarctic Cold Reversal (ACR). This occurs at ca 13000 cal yr BP, just before the onset of the Younger Dryas, and is the onset of the Holocene climate optimum in the circum-Antarctic region. An important plaeoclimatic issue is how far north this pattern can be discerned: is it restricted to the Antarctic-subAntarctic region south of the Antarctic circum-Polar Current or can this pattern be seen in records farther north? We will here present new data that will shed light on this topical issue.