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Where shelf-ice turns passive

Written by Olivier Gagliardini.

 

NCC JohannesThe decadal record of ice-shelf recession and break-up on the Antarctic Peninsula reveals that these vast slabs of floating ice restrain the sea-level relevant outflow from the upstream, well-grounded tributary glaciers. One of the key questions in projecting this outflow for the whole of Antarctica is how far ice-front recession may progress before important dynamic consequences are anticipated. This question is addressed in a recently published article in Nature Climate Change which relies on a continental-scale data assimilation with Elmer/Ice. Details of this assimilation were already presented in an accompanying article published earlier in The Cryosphere. The aim of the data assimilation was to quantify the buttressing effect on ice shelves relying on the inferred stress regime. If maximum buttressing showed values below a threshold, which itself was inferred from generic calving experiments, ice was considered dynamically passive. As long as the calving only removes this passive shelf-ice (PSI) portion, no important dynamic consequences are expected. The results show that 13 % of the total ice-shelf surface of Antarctica hold PSI with contrasting results across the continent. The presented analysis draws again the attention to the Amundsen and Bellingshausen sea sectors, where the PSI area fraction is notably lower, with regional averages of 7 and 5 %, respectively.

News written by Johannes J. Fürst.

Fürst, J. J., G. Durand, F. Gillet-Chaulet, L. Tavard, M. Rankl, M. Braun and O. Gagliardini, 2016. The safety band of Antarctic ice shelves, Nature Climate Change, doi:10.1038/NCLIMATE2912.

 

 

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