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The Cryosphere An interactive open-access journal of the European Geosciences Union
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Discussion papers
https://doi.org/10.5194/tc-2018-252
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/tc-2018-252
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 15 Jan 2019

Research article | 15 Jan 2019

Review status
This discussion paper is a preprint. It is a manuscript under review for the journal The Cryosphere (TC).

Scaling of instability time-scales of Antarctic outlet glaciers based on one-dimensional similitude analysis

Anders Levermann1,2,3 and Johannes Feldmann1 Anders Levermann and Johannes Feldmann
  • 1Potsdam Institute for Climate Impact Research (PIK), Potsdam, Germany
  • 2LDEO, Columbia University, New York, USA
  • 3Institute of Physics, University of Potsdam, Potsdam, Germany

Abstract. Recent observations and ice-dynamic modeling suggest that a marine ice sheet instability (MISI) might have been triggered in West Antarctica. The corresponding outlet glaciers, Pine Island Glacier (PIG) and Thwaites Glacier (TG), showed significant retreat during at least the last two decades. While other regions in Antarctica have the topographic predisposition for the same kind of instability it is so far unclear how fast these instabilities would unfold if they were initiated. Here we employ the concept of similitude to estimate the characteristic time scales of several potentially MISI-prone outlet glaciers around the Antarctic coast. The proposed one-dimensional scaling approach combines observational and model data with a scaling analysis of the governing equations for fast ice flow. Evaluating outlet-characteristic ice and bed geometry, surface mass balance and basal friction in the relevant region near the grounding line, we assume that the inferred time scales correspond to the outlet-specific initial responses time to potential destabilization. Our results suggest that TG and PIG have the fastest responses time of all investigated outlets, with TG responding about 1.25 to 2 times as fast as PIG, while other outlets around Antarctica would be up to ten times slower if destabilized. These results have to be viewed in light of the strong assumptions made in their derivation. These include the absence of ice-shelf buttressing, the one-dimensionality of the approach and the uncertainty of the available data, meaning strong caveats of the approach. We argue however that the current topographic situation and the physical conditions of the MISI-prone outlet glaciers carry the information of their respective time scale and that this information can be partially extracted through a similitude analysis. The one-dimensional analysis is only a first step. Whether a two-dimensional analysis is possible is beyond the scope of this study.

Anders Levermann and Johannes Feldmann
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Anders Levermann and Johannes Feldmann
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Short summary
Using scaling analysis we propose that all potential marine ice-sheet instabilities in Antarctica will be slower than the currently observed instability in Amundsen Sea Sector.
Using scaling analysis we propose that all potential marine ice-sheet instabilities in...
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