Rapid Climate Change at Siple Dome, Antarctica

The 1004 m deep ice core from Siple Dome, Antarctica contains a paleoclimate record that spans at least the last 100,000 years. The most striking features of the paleoclimate record are two intervals at roughly 15 and 20 kyr BP. Both events are characterized by a transition period of reduced ice accumulation followed by an abrupt and persistent increase in surface temperatures. For the 15 kyr event the duration of the transition period was less than a few hundred years and ice accumulation dropped to zero or negative rates. The magnitude of the increase in surface temperature was at least 3 degrees and ice accumulation rates where similar before and after the event. For the 20 kyr event the duration of the transition period was less than 100 years and possibly as short as 50 years. The magnitude of the step increase in surface temperature was about 5 degrees and the ice accumulation rate was at least one-third lower after the event than before. Deuterium excess measurements indicate the two events had differe