Late Pliocene Presence / Absence of IRD in the North Atlantic

The late Pliocene was the most recent time in Earth's history to have greater than Pre-Industrial atmospheric concentrations of CO2 and global mean annual temperatures, similar to climate model predictions for the end of this century, and smaller than modern ice sheets. The nature of Northern Hemisphere ice sheets during this period remains poorly constrained. For the first time, we combine outputs derived from a climate model with a thermodynamic iceberg model in order to decipher source regions of ice rafted debris (IRD) found in sediment cores from the North Atlantic Ocean in order to elucidate the nature of ice sheet variability during the late Pliocene. Specifically, we compare the geographical extent of iceberg melt predicted using four scenarios of late Pliocene Northern Hemisphere ice volume (three representing different glacial scenarios approximating Marine Isotope Stage (MIS) M2, and one representing a typical interglacial condition within the mid-Piacenzian Warm Period (mPWP)) with IRD data from core sites in the North Atlantic. Our results suggest ice volume during MIS M2 was greater than during the Pre-Industrial era but less than has been previously suggested. In addition, marine-terminating glaciers were still present during the mPWP. Iceberg model trajectories suggest East Greenland as a potential source of icebergs in accordance with the presence/absence of IRD at sediment core sites within the Labrador Sea. Other potential source regions are also suggested by the model, such as West Greenland and East Canada, and could be differentiated by geochemical provenance testing of late Pliocene North Atlantic IRD.