A simple stress-based cliff-calving law
Over large coastal regions in Greenland and Antarctica the ice sheet calves directly into the ocean. In contrast to ice-shelf calving, an increase in calving from grounded glaciers contributes directly to sea-level rise. Ice cliffs with a glacier freeboard larger than ≈100 m are currently not observ...
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fttibhannoverren:oai:oa.tib.eu:123456789/4907 2023-05-15T13:55:48+02:00 A simple stress-based cliff-calving law Schlemm, T. Levermann, A. 2019 application/pdf https://oa.tib.eu/renate/handle/123456789/4907 https://doi.org/10.34657/3536 eng eng Göttingen : Copernicus GmbH ISSN:1994-0416 DOI:https://doi.org/10.5194/tc-13-2475-2019 https://oa.tib.eu/renate/handle/123456789/4907 https://doi.org/10.34657/3536 CC BY 4.0 Unported https://creativecommons.org/licenses/by/4.0/ frei zugänglich CC-BY Cryosphere 13 (2019), Nr. 9 cliff geometry glacier dynamics ice sheet ice shelf ice thickness iceberg calving sea level change stress field water depth Antarctica Arctic Greenland ddc:550 status-type:publishedVersion doc-type:article doc-type:Text 2019 fttibhannoverren https://doi.org/10.34657/3536 https://doi.org/10.5194/tc-13-2475-2019 2022-07-25T16:17:59Z Over large coastal regions in Greenland and Antarctica the ice sheet calves directly into the ocean. In contrast to ice-shelf calving, an increase in calving from grounded glaciers contributes directly to sea-level rise. Ice cliffs with a glacier freeboard larger than ≈100 m are currently not observed, but it has been shown that such ice cliffs are increasingly unstable with increasing ice thickness. This cliff calving can constitute a self-amplifying ice loss mechanism that may significantly alter sea-level projections both of Greenland and Antarctica. Here we seek to derive a minimalist stress-based parametrization for cliff calving from grounded glaciers whose freeboards exceed the 100 m stability limit derived in previous studies. This will be an extension of existing calving laws for tidewater glaciers to higher ice cliffs. To this end we compute the stress field for a glacier with a simplified two-dimensional geometry from the two-dimensional Stokes equation. First we assume a constant yield stress to derive the failure region at the glacier front from the stress field within the glacier. Secondly, we assume a constant response time of ice failure due to exceedance of the yield stress. With this strongly constraining but very simple set of assumptions we propose a cliff-calving law where the calving rate follows a power-law dependence on the freeboard of the ice with exponents between 2 and 3, depending on the relative water depth at the calving front. The critical freeboard below which the ice front is stable decreases with increasing relative water depth of the calving front. For a dry water front it is, for example, 75 m. The purpose of this study is not to provide a comprehensive calving law but to derive a particularly simple equation with a transparent and minimalist set of assumptions. Article in Journal/Newspaper Antarc* Antarctica Arctic glacier Greenland Ice Sheet Ice Shelf Iceberg* Tidewater Renate - Repositorium für Naturwissenschaften und Technik (TIB Hannover) Arctic Greenland |
institution |
Open Polar |
collection |
Renate - Repositorium für Naturwissenschaften und Technik (TIB Hannover) |
op_collection_id |
fttibhannoverren |
language |
English |
topic |
cliff geometry glacier dynamics ice sheet ice shelf ice thickness iceberg calving sea level change stress field water depth Antarctica Arctic Greenland ddc:550 |
spellingShingle |
cliff geometry glacier dynamics ice sheet ice shelf ice thickness iceberg calving sea level change stress field water depth Antarctica Arctic Greenland ddc:550 Schlemm, T. Levermann, A. A simple stress-based cliff-calving law |
topic_facet |
cliff geometry glacier dynamics ice sheet ice shelf ice thickness iceberg calving sea level change stress field water depth Antarctica Arctic Greenland ddc:550 |
description |
Over large coastal regions in Greenland and Antarctica the ice sheet calves directly into the ocean. In contrast to ice-shelf calving, an increase in calving from grounded glaciers contributes directly to sea-level rise. Ice cliffs with a glacier freeboard larger than ≈100 m are currently not observed, but it has been shown that such ice cliffs are increasingly unstable with increasing ice thickness. This cliff calving can constitute a self-amplifying ice loss mechanism that may significantly alter sea-level projections both of Greenland and Antarctica. Here we seek to derive a minimalist stress-based parametrization for cliff calving from grounded glaciers whose freeboards exceed the 100 m stability limit derived in previous studies. This will be an extension of existing calving laws for tidewater glaciers to higher ice cliffs. To this end we compute the stress field for a glacier with a simplified two-dimensional geometry from the two-dimensional Stokes equation. First we assume a constant yield stress to derive the failure region at the glacier front from the stress field within the glacier. Secondly, we assume a constant response time of ice failure due to exceedance of the yield stress. With this strongly constraining but very simple set of assumptions we propose a cliff-calving law where the calving rate follows a power-law dependence on the freeboard of the ice with exponents between 2 and 3, depending on the relative water depth at the calving front. The critical freeboard below which the ice front is stable decreases with increasing relative water depth of the calving front. For a dry water front it is, for example, 75 m. The purpose of this study is not to provide a comprehensive calving law but to derive a particularly simple equation with a transparent and minimalist set of assumptions. |
format |
Article in Journal/Newspaper |
author |
Schlemm, T. Levermann, A. |
author_facet |
Schlemm, T. Levermann, A. |
author_sort |
Schlemm, T. |
title |
A simple stress-based cliff-calving law |
title_short |
A simple stress-based cliff-calving law |
title_full |
A simple stress-based cliff-calving law |
title_fullStr |
A simple stress-based cliff-calving law |
title_full_unstemmed |
A simple stress-based cliff-calving law |
title_sort |
simple stress-based cliff-calving law |
publisher |
Göttingen : Copernicus GmbH |
publishDate |
2019 |
url |
https://oa.tib.eu/renate/handle/123456789/4907 https://doi.org/10.34657/3536 |
geographic |
Arctic Greenland |
geographic_facet |
Arctic Greenland |
genre |
Antarc* Antarctica Arctic glacier Greenland Ice Sheet Ice Shelf Iceberg* Tidewater |
genre_facet |
Antarc* Antarctica Arctic glacier Greenland Ice Sheet Ice Shelf Iceberg* Tidewater |
op_source |
Cryosphere 13 (2019), Nr. 9 |
op_relation |
ISSN:1994-0416 DOI:https://doi.org/10.5194/tc-13-2475-2019 https://oa.tib.eu/renate/handle/123456789/4907 https://doi.org/10.34657/3536 |
op_rights |
CC BY 4.0 Unported https://creativecommons.org/licenses/by/4.0/ frei zugänglich |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.34657/3536 https://doi.org/10.5194/tc-13-2475-2019 |
_version_ |
1766262650766884864 |