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Published on: March 31, 2023
Ice-shelf collapse from subsurface warming as a trigger for Heinrich events
Shaun A Marcott1, Peter U Clark, Laurie Padman
1Department of Geosciences, Oregon State University, Corvallis, OR 97331, USA. marcotts@geo.oregonstate.edu
Summary
Climate warming, not ice sheet instability, likely triggered Heinrich events. Subsurface ocean warming increased ice shelf melt, leading to Hudson Strait Ice Stream acceleration and massive iceberg discharge.
Area of Science:
- Paleoclimatology
- Glaciology
- Oceanography
Background:
- Heinrich events, episodic iceberg discharges from the Laurentide Ice Sheet, were previously attributed to internal ice-sheet dynamics.
- Their occurrence correlates with significant reductions in the Atlantic meridional overturning circulation (AMOC).
Purpose of the Study:
- To investigate the role of climate in triggering Heinrich events.
- To understand the mechanisms linking AMOC reductions to ice-sheet dynamics.
Main Methods:
- Analysis of Mg/Ca data from benthic foraminifera in the northwest Atlantic.
- Climate-model simulations incorporating ocean-ice shelf interactions.
Main Results:
- Paleoceanographic data reveal basin-wide subsurface ocean warming (approx. 2°C) preceding Heinrich events.
- Climate model simulations show this warming increased basal melt rates of ice shelves fronting the Hudson Strait Ice Stream (HSIS) by ~6 times.
- This enhanced melt leads to ice shelf destabilization and HSIS acceleration.
Conclusions:
- Climate control, specifically ocean warming linked to AMOC reduction, is a primary driver of Heinrich events.
- The findings suggest a mechanism where ocean warming destabilizes ice shelves, leading to catastrophic iceberg discharge from major ice streams.
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