Stability of the West Antarctic ice sheet in a warming world

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Nature Geoscience
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Ice sheets are expected to shrink in size as the world warms, which in turn will raise sea level. The West Antarctic ice sheet is of particular concern, because it was probably much smaller at times during the past million years when temperatures were comparable to levels that might be reached or exceeded within the next few centuries. Much of the grounded ice in West Antarctica lies on a bed that deepens inland and extends well below sea level. Oceanic and atmospheric warming threaten to reduce or eliminate the floating ice shelves that buttress the ice sheet at present. Loss of the ice shelves would accelerate the flow of non-floating ice near the coast. Because of the slope of the sea bed, the consequent thinning could ultimately float much of the ice sheet's interior. In this scenario, global sea level would rise by more than three metres, at an unknown rate. Simplified analyses suggest that much of the ice sheet will survive beyond this century. We do not know how likely or inevitable eventual collapse of the West Antarctic ice sheet is at this stage, but the possibility cannot be discarded. For confident projections of the fate of the ice sheet and the rate of any collapse, further work including the development of well-validated physical models will be required.

At a glance


  1. Rates of elevation change along the Amundsen Coast of West Antarctica as determined from ICESAT by Pritchard et al..
    Figure 1: Rates of elevation change along the Amundsen Coast of West Antarctica as determined from ICESAT by Pritchard et al.9.

    The results are gridded from individual tracks such as those shown in the inset for PIG. Figure reproduced from ref. 9, © 2009 NPG.

  2. Map of Antarctica with red-brown colours indicating the bed elevation of the marine portions of the WAIS.
    Figure 2: Map of Antarctica with red-brown colours indicating the bed elevation of the marine portions of the WAIS14.

    The gray shaded regions show the East Antarctic ice sheet and the portions of West Antarctica likely to exist following a collapse of the marine ice sheet. Blue shaded regions show areas of East Antarctica where the bed is more than 200 m below sea level. Figure reproduced with permission from ref. 14, © 2009 AAAS.

  3. MODIS image (centre panel) with history of retreat leading up to the collapse of the Larsen B ice shelf.
    Figure 3: MODIS image (centre panel) with history of retreat leading up to the collapse of the Larsen B ice shelf98.

    The side plots show the flow speed before and after the collapse. Note there was little or no speedup on Flask and Leppard glaciers, which flow into the remnant ice shelf and remain well buttressed. Figure reproduced with permission from ref. 98, © 2004 AGU.


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  1. Applied Physics Laboratory, Polar Science Center, University of Washington, 1013 NE 40th Street, Seattle, Washington 98105-6698, USA

    • Ian Joughin
  2. Department of Geosciences, and Earth and Environmental Systems Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA

    • Richard B. Alley

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