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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ftdoajarticles:oai:doaj.org/article:ec3a3a0f67f44ac7b0357256121cd547 2023-05-15T13:34:55+02:00 A simple stress-based cliff-calving law T. Schlemm A. Levermann 2019-09-01T00:00:00Z https://doi.org/10.5194/tc-13-2475-2019 https://doaj.org/article/ec3a3a0f67f44ac7b0357256121cd547 EN eng Copernicus Publications https://www.the-cryosphere.net/13/2475/2019/tc-13-2475-2019.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-13-2475-2019 1994-0416 1994-0424 https://doaj.org/article/ec3a3a0f67f44ac7b0357256121cd547 The Cryosphere, Vol 13, Pp 2475-2488 (2019) Environmental sciences GE1-350 Geology QE1-996.5 article 2019 ftdoajarticles https://doi.org/10.5194/tc-13-2475-2019 2022-12-31T04:30:58Z 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 glacier Greenland Ice Sheet Ice Shelf The Cryosphere Tidewater Directory of Open Access Journals: DOAJ Articles Greenland The Cryosphere 13 9 2475 2488 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Environmental sciences GE1-350 Geology QE1-996.5 |
spellingShingle |
Environmental sciences GE1-350 Geology QE1-996.5 T. Schlemm A. Levermann A simple stress-based cliff-calving law |
topic_facet |
Environmental sciences GE1-350 Geology QE1-996.5 |
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 |
T. Schlemm A. Levermann |
author_facet |
T. Schlemm A. Levermann |
author_sort |
T. Schlemm |
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 |
Copernicus Publications |
publishDate |
2019 |
url |
https://doi.org/10.5194/tc-13-2475-2019 https://doaj.org/article/ec3a3a0f67f44ac7b0357256121cd547 |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Antarc* Antarctica glacier Greenland Ice Sheet Ice Shelf The Cryosphere Tidewater |
genre_facet |
Antarc* Antarctica glacier Greenland Ice Sheet Ice Shelf The Cryosphere Tidewater |
op_source |
The Cryosphere, Vol 13, Pp 2475-2488 (2019) |
op_relation |
https://www.the-cryosphere.net/13/2475/2019/tc-13-2475-2019.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-13-2475-2019 1994-0416 1994-0424 https://doaj.org/article/ec3a3a0f67f44ac7b0357256121cd547 |
op_doi |
https://doi.org/10.5194/tc-13-2475-2019 |
container_title |
The Cryosphere |
container_volume |
13 |
container_issue |
9 |
container_start_page |
2475 |
op_container_end_page |
2488 |
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1766059051257430016 |