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NSF Award:

Collaborative Research: Ice-flow history of the Thwaites Glacier, West Antarctica  (University of Texas at Austin)

IPY: Collaborative Proposal: Constraining the Mass-Balance Deficit of the Amundsen Coast's Glaciers  (University of Washington)

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Nearly 40 years of satellite imagery reveals that west Antarctic ice shelves floating in the Amundsen Sea are steadily losing their grip on adjacent bay walls. The research, by glaciologists at The University of Texas at Austin, suggests that the retreat pattern could potentially amplify an accelerating loss of ice to the sea.

The imagery record created in this study will give scientists a better understanding of the recent evolution of west Antarctica's ice shelves. Knowing why these changes occur is critical for predicting future changes. Previously, most computer models have neglected this specific pattern of ice-shelf retreat.

The Amundsen Sea Embayment is one of the few places in Antarctica with good long-term satellite coverage of its coastline. This comprehensive record shows clearly that the ice shelves changed substantially between the beginning of the Landsat satellite record in 1972 and late 2011. These changes were especially rapid during the past decade. The affected ice shelves include the floating extensions of the rapidly thinning Thwaites and Pine Island glaciers.

Normally, the ice shelves grip onto rocky bay walls or slower ice masses at their very edge. However, as that grip continues to loosen, these already-thinning ice shelves lose their ability to hold back upstream ice. The fractured edges retreat inland until the detached icebergs finally drift out to the open sea. On satellite images this retreat resembles a cracked mirror. The pattern is believed to be a symptom, rather than a trigger, of the recent glacier acceleration in this region. However, it could also generate additional acceleration.

Images (1 of )

  • rifts and surface crevasses near pine island glacier's grounding line
  • fracturing in the amundsen sea ice shelves captured by satellites
Rifts and surface crevasses near Pine Island Glacier's grounding line.
Ian Joughin, University of Washington
Satellite images capture fracturing in the Amundsen Sea ice shelves.
Joseph MacGregor, The University of Texas at Austin

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