NOAA/WDS Paleoclimatology - Atlantic Deglacial Mg/Ca SST and d18Osw Reconstructions

During the last deglaciation (ca. 21-10 ka), freshening of the North Atlantic surface likely caused reductions in Atlantic meridional overturning circulation (AMOC); the mechanisms related to AMOC recovery remain poorly understood. Here we present three new deglacial surface temperature and d18Oseawater (d18Osw) reconstructions from the western subtropical North and South Atlantic. Similarities to tropical Caribbean and western Atlantic d18Osw records suggest that a salty surface water mass accumulated in the western Atlantic from 27°S to 33°N during periods of reduced AMOC. However, d18Osw decreases led deep AMOC resumption by hundreds of years. We suggest that the northward export of salt previously trapped in the western Atlantic resulted in the early establishment of a shallow overturning circulation that eventually culminated in deep AMOC resumption, implying that AMOC may constitute a self-limiting system.