Timing of Deglacial AMOC Variability from a High-resolution Seawater Cadmium Reconstruction

Abstract

A new, high-resolution record of benthic seawater Cd (Cdw) was generated from a Florida Straits sediment core at 546 m water depth. The record provides additional evidence for Cdw below modern values in this channel during the Younger Dryas and Heinrich Stadial 1 - climatological periods associated with ice sheet melt. Lower Cdw values are interpreted as a weakening of the Atlantic Meridional Overturning Circulation (AMOC), reflecting a decreased northward transport of southern-sourced higher-nutrient intermediate waters by the surface return flow of AMOC. Comparison of this new Cdw record with previously published neodymium isotope and δ18O records from the same core shows synchronous transitions, further illustrating the connection between Cdw levels and AMOC strength in the Florida Straits. An increase in Cdw near 16 ka bolsters existing evidence for a resumption of upper branch AMOC strength approximately midway through Heinrich Stadial 1.