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The Cryosphere An interactive open-access journal of the European Geosciences Union
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Preprints
https://doi.org/10.5194/tcd-8-2043-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/tcd-8-2043-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.

  25 Apr 2014

25 Apr 2014

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This preprint was under review for the journal TC but the revision was not accepted.

Quantifying the Jakobshavn Effect: Jakobshavn Isbrae, Greenland, compared to Byrd Glacier, Antarctica

T. Hughes1, A. Sargent2, J. Fastook3, K. Purdon4, J. Li5, J.-B. Yan5, and S. Gogineni6 T. Hughes et al.
  • 1School of Earth and Climate Sciences, Climate Change Institute, University of Maine, Orono, USA
  • 2Department of Mathematics and Statistics, University of Maine, Orono, USA
  • 3Computer Sciences Department, Climate Change Institute, University of Maine, Orono, USA
  • 4Center for Remote Sensing of Ice Sheets, Geography Department, University of Kansas, Lawrence, USA
  • 5Center for Remote Sensing of Ice Sheets, University of Kansas, Lawrence, USA
  • 6Center for Remote Sensing of Ice Sheets, Department of Electrical Engineering and Computer Science, University of Kansas, Lawrence, USA

Abstract. The Jakobshavn Effect is a series of positive feedback mechanisms that was first observed on Jakobshavn Isbrae, which drains the west-central part of the Greenland Ice Sheet and enters Jakobshavn Isfjord at 69°10'. These mechanisms fall into two categories, reductions of ice-bed coupling beneath an ice stream due to surface meltwater reaching the bed, and reductions in ice-shelf buttressing beyond an ice stream due to disintegration of a laterally confined and locally pinned ice shelf. These uncoupling and unbuttressing mechanisms have recently taken place for Byrd Glacier in Antarctica and Jakobshavn Isbrae in Greenland, respectively. For Byrd Glacier, no surface meltwater reaches the bed. That water is supplied by drainage of two large subglacial lakes where East Antarctic ice converges strongly on Byrd Glacier. Results from modeling both mechanisms are presented here. We find that the Jakobshavn Effect is not active for Byrd Glacier, but is active for Jakobshavn Isbrae, at least for now. Our treatment is holistic in the sense it provides continuity from sheet flow to stream flow to shelf flow. It relies primarily on a force balance, so our results cannot be used to predict long-term behavior of these ice streams. The treatment uses geometrical representations of gravitational and resisting forces that provide a visual understanding of these forces, without involving partial differential equations and continuum mechanics. The Jakobshavn Effect was proposed to facilitate terminations of glaciation cycles during the Quaternary Ice Age by collapsing marine parts of ice sheets. This is unlikely for the Antarctic and Greenland ice sheets, based on our results for Byrd Glacier and Jakobshavn Isbrae, without drastic climate warming in high polar latitudes. Warming would affect other Antarctic ice streams already weakly buttressed or unbuttressed by an ice shelf. Ross Ice Shelf would still protect Byrd Glacier.

T. Hughes et al.

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T. Hughes et al.

T. Hughes et al.

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