DEGLACIAL MELTWATER DISCHARGE, NORTH-ATLANTIC DEEP CIRCULATION, AND ABRUPT CLIMATE CHANGE

High-resolution paleogeochemical data from the North Atlantic Ocean indicate that in the interval 15,000 to 10,000 C-14 years before present (B.P.) North Atlantic Deep Water (NADW) production was decreased or eliminated four times: at about 14,500 (and probably older), 13,500, 12,000 and 10,500 years B.P. Each of these changes occurred at the same time as abrupt events of meltwater discharge to the surface ocean (inferred from oxygen isotope studies of planktonic foraminifera and from glacial geological studies on land). In addition, each of these times may be associated with brief episodes of cooler climate in the North Atlantic region, the best example of which is the Younger Dryas cooling of 10,500 years ago. These results support models linking meltwater discharge, decreased NADW production, and decreased North Atlantic heat flux.