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Observed rapid bedrock uplift in Amundsen Sea Embayment promotes ice-sheet stability

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Science  22 Jun 2018:
Vol. 360, Issue 6395, pp. 1335-1339
DOI: 10.1126/science.aao1447

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A quick rebound for Antarctic crust

Earth's crust deforms under the load of glaciers and ice sheets. When these masses are removed, the crust rebounds at a time scale determined by the viscosity of the upper mantle. Using GPS, Barletta et al. found that the viscosity of the mantle under the West Antarctic Ice Sheet is much lower than expected. This means that as ice is lost, the crust rebounds much faster than previously expected. Although estimates of total ice loss have to be revised upward, the surprising finding indicates that the ice sheet may stabilize against catastrophic collapse.

Science, this issue p. 1335

Abstract

The marine portion of the West Antarctic Ice Sheet (WAIS) in the Amundsen Sea Embayment (ASE) accounts for one-fourth of the cryospheric contribution to global sea-level rise and is vulnerable to catastrophic collapse. The bedrock response to ice mass loss, glacial isostatic adjustment (GIA), was thought to occur on a time scale of 10,000 years. We used new GPS measurements, which show a rapid (41 millimeters per year) uplift of the ASE, to estimate the viscosity of the mantle underneath. We found a much lower viscosity (4 × 1018 pascal-second) than global average, and this shortens the GIA response time scale to decades up to a century. Our finding requires an upward revision of ice mass loss from gravity data of 10% and increases the potential stability of the WAIS against catastrophic collapse.

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