Interaction between ice sheet dynamics and sea surface characteristics in the Labrador Sea during the last 50 ka

The study of the history of ice sheet retreat provides important insights into the interaction between ice sheets and oceans, especially under a sustained warming climate. The decay of ice sheets may affect the surrounding ocean environment, and changes in sea surface conditions can, in turn, affect the ice sheet stability. However, interactions between ice sheet dynamics and sea surface characteristics are still not fully understood. Here, we show sedimentary records from the eastern Labrador Sea, proximal to the Laurentide Ice Sheet (LIS) and the Greenland Ice Sheet (GrIS). These records span the last 50 ka, i.e., the last glacial-deglacial-Holocene period. The XRF, biomarker, and planktic/benthic foraminifer data document the collapse of the LIS/iceberg discharge during Heinrich Events (i.e., HE5, HE4, HE2, and HE1) and the occurrence of meltwater plumes from the GrIS and the LIS during the last deglaciation. Such meltwater discharges have caused surface freshening in the Labrador Sea and, consequently, decreased sea surface temperatures and open-water phytoplankton productivity. Enhanced Irminger Current inflow might have caused (sub-)surface warming in the Labrador Sea and triggered the retreat of ice sheets/meltwater discharge. In contrast to relatively low primary production during the glacial period, the Last Glacial Maximum was characterized by increased sea ice algae and phytoplankton production, suggesting the presence of a polynya in front of the southern GrIS.