Ice-shelf collapse from subsurface warming as a trigger for Heinrich events

Episodic iceberg-discharge events from the Hudson Strait Ice Stream (HSIS) of the Laurentide Ice Sheet, referred to as Heinrich events, are commonly attributed to internal ice-sheet instabilities, but their systematic occurrence at the culmination of a large reduction in the Atlantic meridional over...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences
Main Authors: Marcott, Shaun A., Clark, Peter U., Padman, Laurie, Klinkhammer, Gary P., Springer, Scott R., Liu, Zhengyu, Otto-bliesner, Bette L., Carlson, Anders E., Ungerer, Andy, Padman, June, He, Feng, Cheng, Jun, Schmittner, Andreas
Format: Article in Journal/Newspaper
Language:English
Published: Natl Acad Sciences 2011
Subjects:
paleoceanography
paleoclimatology
abrupt climate change
Hudson
Hudson Strait
Antarc*
Antarctica
Ice Sheet
Ice Shelf
Northwest Atlantic
Online Access:https://archimer.ifremer.fr/doc/00227/33819/32479.pdf
https://archimer.ifremer.fr/doc/00227/33819/32480.pdf
https://doi.org/10.1073/pnas.1104772108
https://archimer.ifremer.fr/doc/00227/33819/
Description
Summary:Episodic iceberg-discharge events from the Hudson Strait Ice Stream (HSIS) of the Laurentide Ice Sheet, referred to as Heinrich events, are commonly attributed to internal ice-sheet instabilities, but their systematic occurrence at the culmination of a large reduction in the Atlantic meridional overturning circulation (AMOC) indicates a climate control. We report Mg/Ca data on benthic foraminifera from an intermediate-depth site in the northwest Atlantic and results from a climate-model simulation that reveal basin-wide subsurface warming at the same time as large reductions in the AMOC, with temperature increasing by approximately 2 C over a 1-2 kyr interval prior to a Heinrich event. In simulations with an ocean model coupled to a thermodynamically active ice shelf, the increase in subsurface temperature increases basal melt rate under an ice shelf fronting the HSIS by a factor of approximately 6. By analogy with recent observations in Antarctica, the resulting ice-shelf loss and attendant HSIS acceleration would produce a Heinrich event.

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