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Proc Natl Acad Sci U S A. 2011 Aug 16;108(33):13415-9. doi: 10.1073/pnas.1104772108. Epub 2011 Aug 1.

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

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1
Department of Geosciences, Oregon State University, Corvallis, OR 97331, USA. marcotts@geo.oregonstate.edu

Abstract

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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PMID:
21808034
PMCID:
PMC3158189
DOI:
10.1073/pnas.1104772108
[Indexed for MEDLINE]
Free PMC Article
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