Dynamical processes involved in the retreat of marine ice sheets
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...
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International Glaciological Society
2001
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ftnerc:oai:nora.nerc.ac.uk:19614 2023-05-15T13:45:12+02:00 Dynamical processes involved in the retreat of marine ice sheets Hindmarsh, Richard C.A. Le Meur, E. 2001 http://nora.nerc.ac.uk/id/eprint/19614/ unknown International Glaciological Society Hindmarsh, Richard C.A. orcid:0000-0003-1633-2416 Le Meur, E. 2001 Dynamical processes involved in the retreat of marine ice sheets. Journal of Glaciology, 47 (157). https://doi.org/10.3189/172756501781832269 <https://doi.org/10.3189/172756501781832269> Publication - Article PeerReviewed 2001 ftnerc https://doi.org/10.3189/172756501781832269 2023-02-04T19:32:26Z 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. Article in Journal/Newspaper Antarc* Antarctic Ice Sheet Ice Shelf Journal of Glaciology Natural Environment Research Council: NERC Open Research Archive Antarctic West Antarctic Ice Sheet Payne ENVELOPE(167.867,167.867,-72.817,-72.817) Journal of Glaciology 47 157 271 282 |
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Open Polar |
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Natural Environment Research Council: NERC Open Research Archive |
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ftnerc |
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unknown |
description |
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. |
format |
Article in Journal/Newspaper |
author |
Hindmarsh, Richard C.A. Le Meur, E. |
spellingShingle |
Hindmarsh, Richard C.A. Le Meur, E. Dynamical processes involved in the retreat of marine ice sheets |
author_facet |
Hindmarsh, Richard C.A. Le Meur, E. |
author_sort |
Hindmarsh, Richard C.A. |
title |
Dynamical processes involved in the retreat of marine ice sheets |
title_short |
Dynamical processes involved in the retreat of marine ice sheets |
title_full |
Dynamical processes involved in the retreat of marine ice sheets |
title_fullStr |
Dynamical processes involved in the retreat of marine ice sheets |
title_full_unstemmed |
Dynamical processes involved in the retreat of marine ice sheets |
title_sort |
dynamical processes involved in the retreat of marine ice sheets |
publisher |
International Glaciological Society |
publishDate |
2001 |
url |
http://nora.nerc.ac.uk/id/eprint/19614/ |
long_lat |
ENVELOPE(167.867,167.867,-72.817,-72.817) |
geographic |
Antarctic West Antarctic Ice Sheet Payne |
geographic_facet |
Antarctic West Antarctic Ice Sheet Payne |
genre |
Antarc* Antarctic Ice Sheet Ice Shelf Journal of Glaciology |
genre_facet |
Antarc* Antarctic Ice Sheet Ice Shelf Journal of Glaciology |
op_relation |
Hindmarsh, Richard C.A. orcid:0000-0003-1633-2416 Le Meur, E. 2001 Dynamical processes involved in the retreat of marine ice sheets. Journal of Glaciology, 47 (157). https://doi.org/10.3189/172756501781832269 <https://doi.org/10.3189/172756501781832269> |
op_doi |
https://doi.org/10.3189/172756501781832269 |
container_title |
Journal of Glaciology |
container_volume |
47 |
container_issue |
157 |
container_start_page |
271 |
op_container_end_page |
282 |
_version_ |
1766216848995516416 |