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Dynamical processes involved in the retreat of marine ice sheets

Hindmarsh, Richard C.A.; Le Meur, E.. 2001 Dynamical processes involved in the retreat of marine ice sheets. Journal of Glaciology, 47 (157). 10.3189/172756501781832269

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Abstract/Summary

Marine ice sheets with mechanics described by the shallow-ice approximation by definition do not couple mechanically with the shelf. Such ice sheets are known to have neutral equilibria. We consider the implications of this for their dynamics and in particular for mechanisms which promote marine ice-sheet retreat. The removal of ice-shelf buttressing leading to enhanced flow in grounded ice is discounted as a significant influence on mechanical grounds. Sea-level rise leading to reduced effective pressures under ice streams is shown to be a feasible mechanism for producing postglacial West Antarctic ice-sheet retreat but is inconsistent with borehole evidence. Warming thins the ice sheet by reducing the average viscosity but does not lead to grounding-line retreat. Internal oscillations either specified or generated via a MacAyeal-Payne thermal mechanism promote migration. This is a noise-induced drift phenomenon stemming from the neutral equilibrium property of marine ice sheets. This migration occurs at quite slow rates, but these are sufficiently large to have possibly played a role in the dynamics of the West Antarctic ice sheet after the glacial maximum. Numerical experiments suggest that it is generally true that while significant changes in thickness can be caused by spatially uniform changes, spatial variability coupled with dynamical variability is needed to cause margin movement.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.3189/172756501781832269
Programmes: BAS Programmes > Antarctic Science in the Global Context (2000-2005) > Global Interactions of the Antarctic Ice Sheet
ISSN: 0022-1430
Date made live: 18 Sep 2012 13:33
URI: http://nora.nerc.ac.uk/id/eprint/19614

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