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

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  • Tom Bradwell
    University of Stirling
  • David Small
    NERC (British Geological Survey)
  • Derek Fabel
    Scottish Universities Environmental Research Centre
  • Rachel Smedley
    University of Liverpool
  • Chris Clark
    University of Sheffield
  • Margot Saher
  • Louise Callard
    Durham University
  • Richard Chiverrell
    Liverpool University
  • Dayton Dove
    NERC (British Geological Survey)
  • Steven Moreton
    NERC Radiocarbon Facility, East Kilbride
  • David Roberts
    Durham University
  • Geoff Duller
    Aberystwyth University
  • Colm O'Cofaigh
    Durham University
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.
Original languageEnglish
Article numbereaau1380
Pages (from-to)eaau1380
JournalScience Advances
Volume5
Issue number4
Early online date3 Apr 2019
DOIs
Publication statusPublished - 24 Apr 2019
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