Rapid climate changes in the tropical Atlantic region during the last deglaciation

Abstract

THE climate system is capable of changing abruptly from one stable mode to another1–3. Rapid climate oscillations—in particular the Younger Dryas cold period during the last deglaciation—have long been recognized from records throughout the North Atlantic region4–14, and the distribution of these records at mostly high latitudes suggests that the changes were caused by rapid reorganizations of the North Atlantic thermohaline circulation6,8,10,15. But events far from the North Atlantic region that are synchronous with the Younger Dryas16–19 raise the possibility that a more global forcing mechanism was responsible20. Here we present high-resolution records of laminated sediments of the last deglaciation from the Cariaco basin (tropical Atlantic Ocean) which show many abrupt sub-decade to century-scale oscillations in surface-ocean biological productivity that are synchronous with climate changes at high latitudes. We attribute these productivity variations to changes in or duration of up-welling rate (and hence nutrient supply) caused by changes in trade-wind strength, which is in turn influenced by the thermo-haline circulation through its effect on sea surface temperature6,21. Abrupt climate changes in the tropical Atlantic during the last deglaciation are thus consistent with a North Atlantic circulation forcing mechanism.