Ice-stream demise dynamically conditioned by trough shape and bed strength

Bradwell, Tom; Small, David; Fabel, Derek; Smedley, Rachel K.; Clark, Chris D.; Saher, Margot H.; Callard, S. Louise; Chiverrell, Richard C.; Dove, Dayton; Moreton, Steven G.; Roberts, David H.; Duller, Geoff A. T.; Ó Cofaigh, Colm. 2019 Ice-stream demise dynamically conditioned by trough shape and bed strength. Science Advances, 5 (4), eaau1380. 10.1126/sciadv.aau1380

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Abstract/Summary

Ice sheet mass loss is currently dominated by fast-flowing glaciers (ice streams) terminating in the ocean as ice shelves and resting on beds below sea level. The factors controlling ice-stream flow and retreat over longer time scales (>100 years), especially the role of three-dimensional bed shape and bed strength, remain major uncertainties. We focus on a former ice stream where trough shape and bed substrate are known, or can be defined, to reconstruct ice-stream retreat history and grounding-line movements over 15 millennia since the Last Glacial Maximum. We identify a major behavioral step change around 18,500 to 16,000 years ago—out of tune with external forcing factors—associated with the collapse of floating ice sectors and rapid ice-front retreat. We attribute this step change to a marked geological transition from a soft/weak bed to a hard/strong bed coincident with a change in trough geometry. Both these factors conditioned and ultimately hastened ice-stream demise.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1126/sciadv.aau1380
ISSN:	2375-2548
Date made live:	02 Aug 2019 10:48 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/524611

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