The stability of present-day Antarctic grounding lines – Part B: Possible commitment of regional collapse under current climate
Observations of ocean-driven grounding line retreat in the Amundsen Sea Embayment in Antarctica give rise to the question of a collapse of the West Antarctic Ice Sheet. Here we analyse the committed evolution of Antarctic grounding lines under present-day climate conditions to locate the underlying...
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ftcopernicus:oai:publications.copernicus.org:tcd103470 2023-05-15T13:23:50+02:00 The stability of present-day Antarctic grounding lines – Part B: Possible commitment of regional collapse under current climate Reese, Ronja Garbe, Julius Hill, Emily A. Urruty, Benoît Naughten, Kaitlin A. Gagliardini, Olivier Durand, Gael Gillet-Chaulet, Fabien Chandler, David Langebroek, Petra M. Winkelmann, Ricarda 2022-05-31 application/pdf https://doi.org/10.5194/tc-2022-105 https://tc.copernicus.org/preprints/tc-2022-105/ eng eng doi:10.5194/tc-2022-105 https://tc.copernicus.org/preprints/tc-2022-105/ eISSN: 1994-0424 Text 2022 ftcopernicus https://doi.org/10.5194/tc-2022-105 2022-06-06T16:22:43Z Observations of ocean-driven grounding line retreat in the Amundsen Sea Embayment in Antarctica give rise to the question of a collapse of the West Antarctic Ice Sheet. Here we analyse the committed evolution of Antarctic grounding lines under present-day climate conditions to locate the underlying steady states that they are attracted to and understand the reversibility of large-scale changes. To this aim, we first calibrate the sub-shelf melt module PICO with observed and modelled melt sensitivities to ocean temperature changes. Using the new calibration, we run an ensemble of historical simulations from 1850 to 2015 with the Parallel Ice Sheet Model to create model instances of possible present-day ice sheet configurations. Then, we extend a subset of simulations best representing the present-day ice sheet for another 10,000 years to investigate their evolution under constant present-day climate forcing. We test for reversibility of grounding line movement if large-scale retreat occurs. While we find parameter combinations for which no retreat happens in the Amundsen Sea Embayment sector, we also find admissible model parameters for which an irreversible retreat takes place. Hence, it cannot be ruled out that the grounding lines – which are not engaged in an irreversible retreat at the moment as shown in our companion paper (Part A, Urruty et al., subm.) – will evolve towards such a retreat under current climate conditions. Importantly, an irreversible collapse in the Amundsen Sea Embayment sector evolves on millennial timescales and is not inevitable yet, but could become so if forcing on the climate system is not reduced in the future. In contrast, we find that allowing ice shelves to regrow to their present geometry means that large-scale grounding line retreat into marine basins upstream of Filchner-Ronne and Ross ice shelves is reversible. Other grounding lines remain close to their current positions in all configurations under present-day climate. Text Amundsen Sea Antarc* Antarctic Antarctica Ice Sheet Ice Shelves Copernicus Publications: E-Journals Antarctic Amundsen Sea West Antarctic Ice Sheet |
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Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
Observations of ocean-driven grounding line retreat in the Amundsen Sea Embayment in Antarctica give rise to the question of a collapse of the West Antarctic Ice Sheet. Here we analyse the committed evolution of Antarctic grounding lines under present-day climate conditions to locate the underlying steady states that they are attracted to and understand the reversibility of large-scale changes. To this aim, we first calibrate the sub-shelf melt module PICO with observed and modelled melt sensitivities to ocean temperature changes. Using the new calibration, we run an ensemble of historical simulations from 1850 to 2015 with the Parallel Ice Sheet Model to create model instances of possible present-day ice sheet configurations. Then, we extend a subset of simulations best representing the present-day ice sheet for another 10,000 years to investigate their evolution under constant present-day climate forcing. We test for reversibility of grounding line movement if large-scale retreat occurs. While we find parameter combinations for which no retreat happens in the Amundsen Sea Embayment sector, we also find admissible model parameters for which an irreversible retreat takes place. Hence, it cannot be ruled out that the grounding lines – which are not engaged in an irreversible retreat at the moment as shown in our companion paper (Part A, Urruty et al., subm.) – will evolve towards such a retreat under current climate conditions. Importantly, an irreversible collapse in the Amundsen Sea Embayment sector evolves on millennial timescales and is not inevitable yet, but could become so if forcing on the climate system is not reduced in the future. In contrast, we find that allowing ice shelves to regrow to their present geometry means that large-scale grounding line retreat into marine basins upstream of Filchner-Ronne and Ross ice shelves is reversible. Other grounding lines remain close to their current positions in all configurations under present-day climate. |
format |
Text |
author |
Reese, Ronja Garbe, Julius Hill, Emily A. Urruty, Benoît Naughten, Kaitlin A. Gagliardini, Olivier Durand, Gael Gillet-Chaulet, Fabien Chandler, David Langebroek, Petra M. Winkelmann, Ricarda |
spellingShingle |
Reese, Ronja Garbe, Julius Hill, Emily A. Urruty, Benoît Naughten, Kaitlin A. Gagliardini, Olivier Durand, Gael Gillet-Chaulet, Fabien Chandler, David Langebroek, Petra M. Winkelmann, Ricarda The stability of present-day Antarctic grounding lines – Part B: Possible commitment of regional collapse under current climate |
author_facet |
Reese, Ronja Garbe, Julius Hill, Emily A. Urruty, Benoît Naughten, Kaitlin A. Gagliardini, Olivier Durand, Gael Gillet-Chaulet, Fabien Chandler, David Langebroek, Petra M. Winkelmann, Ricarda |
author_sort |
Reese, Ronja |
title |
The stability of present-day Antarctic grounding lines – Part B: Possible commitment of regional collapse under current climate |
title_short |
The stability of present-day Antarctic grounding lines – Part B: Possible commitment of regional collapse under current climate |
title_full |
The stability of present-day Antarctic grounding lines – Part B: Possible commitment of regional collapse under current climate |
title_fullStr |
The stability of present-day Antarctic grounding lines – Part B: Possible commitment of regional collapse under current climate |
title_full_unstemmed |
The stability of present-day Antarctic grounding lines – Part B: Possible commitment of regional collapse under current climate |
title_sort |
stability of present-day antarctic grounding lines – part b: possible commitment of regional collapse under current climate |
publishDate |
2022 |
url |
https://doi.org/10.5194/tc-2022-105 https://tc.copernicus.org/preprints/tc-2022-105/ |
geographic |
Antarctic Amundsen Sea West Antarctic Ice Sheet |
geographic_facet |
Antarctic Amundsen Sea West Antarctic Ice Sheet |
genre |
Amundsen Sea Antarc* Antarctic Antarctica Ice Sheet Ice Shelves |
genre_facet |
Amundsen Sea Antarc* Antarctic Antarctica Ice Sheet Ice Shelves |
op_source |
eISSN: 1994-0424 |
op_relation |
doi:10.5194/tc-2022-105 https://tc.copernicus.org/preprints/tc-2022-105/ |
op_doi |
https://doi.org/10.5194/tc-2022-105 |
_version_ |
1766375705763905536 |