Sack Lunch Seminar (SLS)

I will present a suite of records from a 950 m-depth sediment core from the western North Atlantic, a site influenced by Antarctic Intermediate Water (AAIW) in the modern ocean. The data suggest that northern sourced waters dominated the water mass mixture during the LGM, and that AAIW was shallower than ~850m. A d18O decrease early in Heinrich Stadial 1 (HS1) is attributed to the incorporation of deglacial meltwater into the northern sourced waters that continued to influence the site. Two interpretations for the mid-to-late HS1 data will be discussed, having opposite implications for the vigor of the Atlantic Meridional Overturning Circulation (AMOC) during this interval. After HS1, the data conform to the consensus view of AMOC variability – increased AAIW presence during the Bolling-Allerod and the Holocene, when the AMOC was strong, and reduced AAIW presence during the Younger Dryas when the AMOC was weak.