During the last glacial period, massive discharges of icebergs repeatedly flushed the North Atlantic. Termed Heinrich events, the release of icebergs disrupted ocean circulation and led to globally recorded climate change. Ice-rafted debris, the sedimentary signature of iceberg melting, offers clues on when, where, and how much icebergs melted in the past.
I compiled 230Thxs-based mass flux and utilize a novel method to quantify the freshwater flux. Freshwater fluxes between 20° and 70° N were as high as 0.11 Sv during Heinrich event 4 and as low as 0.0012 Sv during event 3. Our results are one to two order of magnitude lower than previous estimates. However, since different methods are liable to unique sets of uncertainties, we see our results as mostly a validation of the previous estimates. A band of high mass flux between 40° and 60° N exists in the western North Atlantic and tapers off in the east. We revise Heinrich event 5 to a radiocarbon-derived age of 48 ka instead of 45 ka as commonly believed.