VARIABILITY OF THE NORTH-ATLANTIC THERMOHALINE CIRCULATION DURING THELAST INTERGLACIAL PERIOD

Studies of natural climate variability are essential for evaluating it s future evolution. Greenland ice cores suggest that the modern warm p eriod (the Holocene) has been relatively stable for the past 9,000 yea rs(1,2). Much less is known about other warm interglacial periods, whi ch comprise less than 10% of the climate record during the past 2.5 mi llion years(3-7). Here we present high-resolution ocean sediment recor ds of surface and deep-water variables from the Bermuda Rise spanning the last interglacial period, about 118,000-127,000 years ago. In gene ral, deep-water chemical changes are coincident with transitions in su rface climate at this site. The records do not show any substantial fl uctuations relative to the much higher variability observed during the preceding and subsequent cool climates. The relatively stable intergl acial period begins and ends with abrupt changes in deep-water now. We estimate, using Th-230 measurements to constrain the chronology, that transitions occur in less than 400 years.