Preprints
https://doi.org/10.5194/tcd-9-1705-2015
https://doi.org/10.5194/tcd-9-1705-2015

  17 Mar 2015

17 Mar 2015

Review status: this preprint has been withdrawn by the authors.

Comparing ice discharge through West Antarctic Gateways: Weddell vs. Amundsen Sea warming

M. A. Martin1, A. Levermann1,2, and R. Winkelmann1,2 M. A. Martin et al.
  • 1Potsdam Institute for Climate Impact Research, Potsdam, Germany
  • 2University of Potsdam, Potsdam, Germany

Abstract. Future changes in Antarctic ice discharge will be largely controlled by the fate of the floating ice shelves, which exert a back-stress onto Antarctica's marine outlet glaciers. Ice loss in response to warming of the Amundsen Sea has been observed and investigated as a potential trigger for the marine ice-sheet instability. Recent observations and simulations suggest that the Amundsen Sea Sector might already be unstable which would have strong implications for global sea-level rise. At the same time, regional ocean projections show much stronger warm-water intrusion into ice-shelf cavities in the Weddell Sea compared to the observed Amundsen warming. Here we present results of numerical ice sheet modelling with the Parallel Ice Sheet Model (PISM) which show that idealized, step-function type ocean warming in the Weddell Sea leads to more immediate ice discharge with a higher sensitivity to small warming levels than the same warming in the Amundsen Sea. This is consistent with the specific combination of bedrock and ice topography in the Weddell Sea Sector which results in an ice sheet close to floatation. In response to even slight ocean warming, ice loss increases rapidly, peaks and declines within one century. While the cumulative ice loss in the Amundsen Sea Sector is of similar magnitude after five centuries of continued warming, ice loss increases at a slower pace and only for significantly higher warming levels. Although there is more marine ice stored above sea level in close vicinity of the grounding line compared to the Weddell Sea Sector, the ice sheet is farther from floatation and the grounding line initially retreats more slowly.

This preprint has been withdrawn.

M. A. Martin et al.

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Interactive discussion

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Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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M. A. Martin et al.

M. A. Martin et al.

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This preprint has been withdrawn.

Short summary
Numerical ice sheet modelling shows that idealized, step-function type ocean warming in the Weddell Sea, where the ice sheet is close to floatation, leads to more immediate ice discharge with a higher sensitivity to small warming levels than the same warming in the Amundsen Sea. While the cumulative ice loss in the Amundsen Sea Sector is of similar magnitude after five centuries of continued warming, ice loss increases at a slower pace and only for significantly higher warming levels.