Shifts in the position of the North Equatorial Current and rapid productivity changes in the western Tropical Atlantic during the last glacial

Abstract

High-resolution, well-dated calcareous dinoflagellate cyst and organic carbon records from a 58 kyr sediment core (M35003-4) located southeast of the island of Grenada show that rapid and pronounced changes in cyst association and accumulation and organic carbon deposition occured, controlled by (1) a significant southward shift in the position of the North Equatorial Current during the last glacial period and the Younger Dryas cold interval and (2) rapid changes in local productivity in marine isotopic stage 3 that are associated with variations in Orinoco River nutrient discharge and coastal upwelling strength. Prominent cyst accumulation peaks representing extremely oligotrophic and stratified thermocline conditions mimic the Greenland ice core and northern Atlantic Dansgaard/Oeschger stadials and Heinrich events. We provide new evidence for a coupled tropical/high-latitude Atlantic climate system during the last glacial period and suggest that changes in the zonality of the low-latitude winds may play an important role in modulating rapid interhemispheric climate variability.