Subtropical Atlantic salinity variability and Atlantic meridional circulation during the last deglaciation

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 delta O-18(seawater) (delta O-18(sw)) reconstructions from the western subtropical North and South Atlantic. Similarities to tropical Caribbean and western Atlantic delta O-18(sw) records suggest that a salty surface water mass accumulated in the western Atlantic from 27 degrees S to 33 degrees N during periods of reduced AMOC. However, delta O-18(sw) 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.