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

TitleIce-shelf collapse from subsurface warming as a trigger for Heinrich events
Publication TypeJournal Article
Year of Publication2011
AuthorsMarcott, S. A., P. U. Clark, L. Padman, G. P. Klinkhammer, S. R. Springer, Z. Y. Liu, B. L. Otto-Bliesner, A. E. Carlson, A. Ungerer, J. Padman, F. He, J. Cheng, and A. Schmittner
JournalProceedings of the National Academy of Sciences of the United States of America
Date PublishedAug 16
ISBN Number0027-8424
Accession NumberISI:000293895100020
Keywordsabrupt climate change, circulation, deglaciation, greenland ice, last glacial period, mechanism, north-atlantic, ocean, paleoceanography, paleoclimatology, rapid changes, sheet, temperature

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.

URL<Go to ISI>://000293895100020