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Stability of the West Antarctic ice sheet in a warming world

Abstract

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.

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Figure 1: Rates of elevation change along the Amundsen Coast of West Antarctica as determined from ICESAT by Pritchard et al.9.
Figure 2: Map of Antarctica with red-brown colours indicating the bed elevation of the marine portions of the WAIS14.
Figure 3: MODIS image (centre panel) with history of retreat leading up to the collapse of the Larsen B ice shelf98.

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Acknowledgements

We acknowledge the contributions from the papers cited in this Review, and just as importantly the immense body of WAIS research that could not be cited due to space constraints. Comments by M. Maki improved the manuscript. The US National Science Foundation supported I.J.'s (ANT-0636719 and ANT-0424589) and R.B.A's (ANT-0424589, ANT-0539578, ANT-0944286 and ANT-0909335) effort. Additional support for RBA was provided by NASA (NNX10AI04G).

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Joughin, I., Alley, R. Stability of the West Antarctic ice sheet in a warming world. Nature Geosci 4, 506–513 (2011). https://doi.org/10.1038/ngeo1194

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