Variability of the North Atlantic thermohaline circulation during the last interglacial period

Abstract

Studies of natural climate variability are essential for evaluating its future evolution. Greenland ice cores suggest that the modern warm period (the Holocene) has been relatively stable for the past 9,000 years. Much less is known about other warm interglacial periods, which comprise less than 10% of the climate record during the past 2.5 million years. Here we present high-resolution ocean sediment records of surface and deep-water variables from the Bermuda Rise spanning the last interglacial period, about 118,000–127,000 years ago. In general, deep-water chemical changes are coincident with transitions in surface climate at this site. The records do not show any substantial fluctuations relative to the much higher variability observed during the preceding and subsequent cool climates. The relatively stable interglacial period begins and ends with abrupt changes in deep-water flow. We estimate, using ^(230)Th measurements to constrain the chronology, that transitions occur in less than 400 years.