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...
Main Authors: | , |
---|---|
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Göttingen : Copernicus GmbH
2019
|
Subjects: | |
Online Access: | https://oa.tib.eu/renate/handle/123456789/4907 https://doi.org/10.34657/3536 |
id |
ftleibnizopen:oai:oai.leibnizopen.de:Oi_ReYsBBwLIz6xGo9Rp |
---|---|
record_format |
openpolar |
spelling |
ftleibnizopen:oai:oai.leibnizopen.de:Oi_ReYsBBwLIz6xGo9Rp 2023-11-12T04:07:43+01:00 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 CC BY 4.0 Unported https://creativecommons.org/licenses/by/4.0/ 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 550 article Text 2019 ftleibnizopen https://doi.org/10.34657/3536 2023-10-30T00:35:12Z 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. Leibniz_Fonds publishedVersion Article in Journal/Newspaper Antarc* Antarctica Arctic glacier Greenland Ice Sheet Ice Shelf Iceberg* Tidewater Unknown |
institution |
Open Polar |
collection |
Unknown |
op_collection_id |
ftleibnizopen |
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 550 |
spellingShingle |
cliff geometry glacier dynamics ice sheet ice shelf ice thickness iceberg calving sea level change stress field water depth Antarctica Arctic Greenland 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 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. Leibniz_Fonds publishedVersion |
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 |
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_rights |
CC BY 4.0 Unported https://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.34657/3536 |
_version_ |
1782328287875301376 |