Brief interstadial events in the Santa Barbara basin, NE Pacific, during the past 60 kyr

THE instability of the Northern Hemisphere glacial climate over the past 100 kyr has been revealed by at least 20 brief warm (interstadial) episodes, called Dansgaard-Oeschger events, recorded in Greenland ice cores(1-3) and in North Atlantic sedimentary records(4,5). A few of these events have been recognized elsewhere(6-8). Here we describe a record of ocean oxygenation and circulation from the Santa Barbara basin in the northeast Pacific Ocean which correlates well,vith the Greenland ice-core records. We see 19 of the 20 Dansgaard-Oeschger events, in the form of laminated sediments deposited under anoxic conditions, and we can correlate at least 16 of these with the 17 ice-core interstadials of the past 60 kyr. Thus, these short-term events were not restricted to the North Atlantic region. The events had substantial ecological and oceanographic effects in the Santa Barbara basin, including changes in benthic faunal populations and in the age and composition of bottom waters. Similar ventilation changes have been seen in the Gulf of California(9,10), suggesting that these changes may have been widespread and synchronous along the northeast Pacific margin. These results suggest sensitivity of broad areas of the ocean-atmosphere-cryosphere system to short-term climate change.