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Nat Commun. 2015 Nov 26;6:8910. doi: 10.1038/ncomms9910.

Rapid Holocene thinning of an East Antarctic outlet glacier driven by marine ice sheet instability.

Author information

1
Antarctic Research Centre, Victoria University of Wellington, Kelburn, Wellington 6012, New Zealand.
2
School of Geography, Environment and Earth Sciences, Victoria University of Wellington, Kelburn, Wellington 6012, New Zealand.
3
GNS Science, Avalon, Lower Hutt 5011, New Zealand.
4
Climate Change Research Centre, University of New South Wales, Sydney 2052, Australia.
5
Laboratory of Ion Beam Physics, Department of Physics, ETH Zurich, Otto Stern Weg 5, 8093 Zurich, Switzerland.
6
Department of Geological Sciences, Stockholm University, 10691 Stockholm, Sweden.

Abstract

Outlet glaciers grounded on a bed that deepens inland and extends below sea level are potentially vulnerable to 'marine ice sheet instability'. This instability, which may lead to runaway ice loss, has been simulated in models, but its consequences have not been directly observed in geological records. Here we provide new surface-exposure ages from an outlet of the East Antarctic Ice Sheet that reveal rapid glacier thinning occurred approximately 7,000 years ago, in the absence of large environmental changes. Glacier thinning persisted for more than two and a half centuries, resulting in hundreds of metres of ice loss. Numerical simulations indicate that ice surface drawdown accelerated when the otherwise steadily retreating glacier encountered a bedrock trough. Together, the geological reconstruction and numerical simulations suggest that centennial-scale glacier thinning arose from unstable grounding line retreat. Capturing these instability processes in ice sheet models is important for predicting Antarctica's future contribution to sea level change.

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