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 ice discharges during Heinrich events. Ice discharges were as high as 165 mSv (1 mSv = 103 m3 s−1) during Heinrich event 4 and as low as 4 mSv during Heinrich event 3. The present-day Greenland Ice Sheet ice discharge is less than that of Heinrich event 4, but comparable within uncertainty to that of most other Heinrich events of the last glaciation. However, future ice discharge from the Greenland Ice Sheet is expected to decrease as it recedes from marine-terminating outlets. Our study suggests that the current level of Greenland Ice Sheet ice discharge likely will not go on for long enough to cause a catastrophic disruption to the Atlantic overturning circulation by the end of the century.
This work is currently in press at Science.