Rapid fragmentation of Thwaites Eastern Ice Shelf

Benn, Douglas I.; Luckman, Adrian; Åström, Jan A.; Crawford, Anna J.; Cornford, Stephen; Bevan, Suzanne; Zwinger, Thomas; Gladstone, Rupert; Alley, Karen; Pettit, Erin; Bassis, Jeremy

doi:10.5194/tc-16-2545-2022

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Rapid fragmentation of Thwaites Eastern Ice Shelf

Douglas I. Benn, Adrian Luckman

, Jan A. Åström, Anna J. Crawford

, Stephen Cornford

, Suzanne Bevan

, Thomas Zwinger

, Rupert Gladstone

, Karen Alley, Erin Pettit

, Jeremy Bassis

The Cryosphere, Volume: 16, Issue: 6, Pages: 2545 - 2564

Swansea University Authors: Adrian Luckman , Stephen Cornford , Suzanne Bevan

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DOI (Published version): 10.5194/tc-16-2545-2022

Abstract

Ice shelves play a key role in the dynamics of marine ice sheets by buttressing grounded ice and limiting rates of ice flux to the oceans. In response to recent climatic and oceanic change, ice shelves fringing the West Antarctic Ice Sheet (WAIS) have begun to fragment and retreat, with major implic...

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Published in:	The Cryosphere
ISSN:	1994-0424
Published:	Copernicus GmbH 2022
Online Access:	Check full text
URI:	https://cronfa.swan.ac.uk/Record/cronfa60470

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In response to recent climatic and oceanic change, ice shelves fringing the West Antarctic Ice Sheet (WAIS) have begun to fragment and retreat, with major implications for ice-sheet stability. Here, we focus on the Thwaites Eastern Ice Shelf (TEIS), the remaining pinned floating extension of Thwaites Glacier. We show that TEIS has undergone a process of fragmentation in the last 5 years, including brittle failure along a major shear zone, formation of tensile cracks on the main body of the shelf, and a release of tabular bergs on both the eastern and western flanks. Simulations with the Helsinki Discrete Element Model (HiDEM) show that this pattern of failure is associated with high backstress from a submarine pinning point at the distal edge of the shelf. We show that a significant zone of shear, upstream of the main pinning point, developed in response to the rapid acceleration of the shelf between 2002 and 2006, seeding damage on the shelf. Subsequently, basal melting and positive feedback between damage and strain rates weakened TEIS, allowing damage to accumulate. Thus, although backstress on TEIS has likely diminished over time as the pinning point shrunk, accumulation of damage has ensured that the ice in the shear zone remained the weakest link in the system. Experiments with the BISICLES ice-sheet model indicate that additional damage to or unpinning of TEIS is unlikely to trigger significantly increased ice loss from WAIS, but the calving response to the loss of TEIS remains highly uncertain. It is widely recognised that ice-shelf fragmentation and collapse can be triggered by hydrofracturing and/or unpinning from ice-shelf margins or grounding points. Our results indicate a third mechanism, backstress triggered failure, that can occur if and when an ice shelf is no longer able to withstand stress imposed by pinning points. In most circumstances, pinning points are essential for ice-shelf stability, but as ice shelves thin and weaken, the concentration of backstress in damaged ice upstream of a pinning point may provide the seeds of their demise.</abstract><type>Journal Article</type><journal>The Cryosphere</journal><volume>16</volume><journalNumber>6</journalNumber><paginationStart>2545</paginationStart><paginationEnd>2564</paginationEnd><publisher>Copernicus GmbH</publisher><placeOfPublication/><isbnPrint/><isbnElectronic/><issnPrint/><issnElectronic>1994-0424</issnElectronic><keywords/><publishedDay>27</publishedDay><publishedMonth>6</publishedMonth><publishedYear>2022</publishedYear><publishedDate>2022-06-27</publishedDate><doi>10.5194/tc-16-2545-2022</doi><url/><notes/><college>COLLEGE NANME</college><department>Biosciences Geography and Physics School</department><CollegeCode>COLLEGE CODE</CollegeCode><DepartmentCode>BGPS</DepartmentCode><institution>Swansea University</institution><apcterm/><funders>Funding was provided by the National Science Foundation (NSF: grant nos. 1738896 and 1929991) and Natural Environment Research Council (NERC: grant no. 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spelling	2022-12-14T09:52:23.7694653 v2 60470 2022-07-13 Rapid fragmentation of Thwaites Eastern Ice Shelf 008cb668b2671b653a88677f075799a9 0000-0002-9618-5905 Adrian Luckman Adrian Luckman true false 17ae00ff2346b8c23d7e2b34341610a4 0000-0003-1844-274X Stephen Cornford Stephen Cornford true false 758d19253522c8c306d4eea0e6e484f6 0000-0003-2649-2982 Suzanne Bevan Suzanne Bevan true false 2022-07-13 BGPS Ice shelves play a key role in the dynamics of marine ice sheets by buttressing grounded ice and limiting rates of ice flux to the oceans. In response to recent climatic and oceanic change, ice shelves fringing the West Antarctic Ice Sheet (WAIS) have begun to fragment and retreat, with major implications for ice-sheet stability. Here, we focus on the Thwaites Eastern Ice Shelf (TEIS), the remaining pinned floating extension of Thwaites Glacier. We show that TEIS has undergone a process of fragmentation in the last 5 years, including brittle failure along a major shear zone, formation of tensile cracks on the main body of the shelf, and a release of tabular bergs on both the eastern and western flanks. Simulations with the Helsinki Discrete Element Model (HiDEM) show that this pattern of failure is associated with high backstress from a submarine pinning point at the distal edge of the shelf. We show that a significant zone of shear, upstream of the main pinning point, developed in response to the rapid acceleration of the shelf between 2002 and 2006, seeding damage on the shelf. Subsequently, basal melting and positive feedback between damage and strain rates weakened TEIS, allowing damage to accumulate. Thus, although backstress on TEIS has likely diminished over time as the pinning point shrunk, accumulation of damage has ensured that the ice in the shear zone remained the weakest link in the system. Experiments with the BISICLES ice-sheet model indicate that additional damage to or unpinning of TEIS is unlikely to trigger significantly increased ice loss from WAIS, but the calving response to the loss of TEIS remains highly uncertain. It is widely recognised that ice-shelf fragmentation and collapse can be triggered by hydrofracturing and/or unpinning from ice-shelf margins or grounding points. Our results indicate a third mechanism, backstress triggered failure, that can occur if and when an ice shelf is no longer able to withstand stress imposed by pinning points. In most circumstances, pinning points are essential for ice-shelf stability, but as ice shelves thin and weaken, the concentration of backstress in damaged ice upstream of a pinning point may provide the seeds of their demise. Journal Article The Cryosphere 16 6 2545 2564 Copernicus GmbH 1994-0424 27 6 2022 2022-06-27 10.5194/tc-16-2545-2022 COLLEGE NANME Biosciences Geography and Physics School COLLEGE CODE BGPS Swansea University Funding was provided by the National Science Foundation (NSF: grant nos. 1738896 and 1929991) and Natural Environment Research Council (NERC: grant no. NE/S006605/1). Rupert Gladstone is supported by Academy of Finland (grant no. 322430), Thomas Zwinger by grant no. 322978. 2022-12-14T09:52:23.7694653 2022-07-13T09:09:26.5385443 Faculty of Science and Engineering School of Biosciences, Geography and Physics - Geography Douglas I. Benn 1 Adrian Luckman 0000-0002-9618-5905 2 Jan A. Åström 3 Anna J. Crawford 0000-0003-3620-1130 4 Stephen Cornford 0000-0003-1844-274X 5 Suzanne Bevan 0000-0003-2649-2982 6 Thomas Zwinger 0000-0003-3360-4401 7 Rupert Gladstone 0000-0002-1582-3857 8 Karen Alley 9 Erin Pettit 0000-0002-6765-9841 10 Jeremy Bassis 11 60470__24814__37463924a2c24cd5aa754c92ae999c17.pdf 60470.pdf 2022-08-02T16:59:47.9703844 Output 20609319 application/pdf Version of Record true © Author(s) 2022. This work is distributed under the Creative Commons Attribution 4.0 License. true eng https://creativecommons.org/licenses/by/4.0/
title	Rapid fragmentation of Thwaites Eastern Ice Shelf
spellingShingle	Rapid fragmentation of Thwaites Eastern Ice Shelf Adrian Luckman Stephen Cornford Suzanne Bevan
title_short	Rapid fragmentation of Thwaites Eastern Ice Shelf
title_full	Rapid fragmentation of Thwaites Eastern Ice Shelf
title_fullStr	Rapid fragmentation of Thwaites Eastern Ice Shelf
title_full_unstemmed	Rapid fragmentation of Thwaites Eastern Ice Shelf
title_sort	Rapid fragmentation of Thwaites Eastern Ice Shelf
author_id_str_mv	008cb668b2671b653a88677f075799a9 17ae00ff2346b8c23d7e2b34341610a4 758d19253522c8c306d4eea0e6e484f6
author_id_fullname_str_mv	008cb668b2671b653a88677f075799a9_*_Adrian Luckman 17ae00ff2346b8c23d7e2b34341610a4__Stephen Cornford 758d19253522c8c306d4eea0e6e484f6_**_Suzanne Bevan
author	Adrian Luckman Stephen Cornford Suzanne Bevan
author2	Douglas I. Benn Adrian Luckman Jan A. Åström Anna J. Crawford Stephen Cornford Suzanne Bevan Thomas Zwinger Rupert Gladstone Karen Alley Erin Pettit Jeremy Bassis
format	Journal article
container_title	The Cryosphere
container_volume	16
container_issue	6
container_start_page	2545
publishDate	2022
institution	Swansea University
issn	1994-0424
doi_str_mv	10.5194/tc-16-2545-2022
publisher	Copernicus GmbH
college_str	Faculty of Science and Engineering
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description	Ice shelves play a key role in the dynamics of marine ice sheets by buttressing grounded ice and limiting rates of ice flux to the oceans. In response to recent climatic and oceanic change, ice shelves fringing the West Antarctic Ice Sheet (WAIS) have begun to fragment and retreat, with major implications for ice-sheet stability. Here, we focus on the Thwaites Eastern Ice Shelf (TEIS), the remaining pinned floating extension of Thwaites Glacier. We show that TEIS has undergone a process of fragmentation in the last 5 years, including brittle failure along a major shear zone, formation of tensile cracks on the main body of the shelf, and a release of tabular bergs on both the eastern and western flanks. Simulations with the Helsinki Discrete Element Model (HiDEM) show that this pattern of failure is associated with high backstress from a submarine pinning point at the distal edge of the shelf. We show that a significant zone of shear, upstream of the main pinning point, developed in response to the rapid acceleration of the shelf between 2002 and 2006, seeding damage on the shelf. Subsequently, basal melting and positive feedback between damage and strain rates weakened TEIS, allowing damage to accumulate. Thus, although backstress on TEIS has likely diminished over time as the pinning point shrunk, accumulation of damage has ensured that the ice in the shear zone remained the weakest link in the system. Experiments with the BISICLES ice-sheet model indicate that additional damage to or unpinning of TEIS is unlikely to trigger significantly increased ice loss from WAIS, but the calving response to the loss of TEIS remains highly uncertain. It is widely recognised that ice-shelf fragmentation and collapse can be triggered by hydrofracturing and/or unpinning from ice-shelf margins or grounding points. Our results indicate a third mechanism, backstress triggered failure, that can occur if and when an ice shelf is no longer able to withstand stress imposed by pinning points. In most circumstances, pinning points are essential for ice-shelf stability, but as ice shelves thin and weaken, the concentration of backstress in damaged ice upstream of a pinning point may provide the seeds of their demise.
published_date	2022-06-27T20:25:29Z
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score	11.047609

Rapid fragmentation of Thwaites Eastern Ice Shelf

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