Sensitivity of Heinrich-type ice-sheet surge characteristics to boundary forcing perturbations
Heinrich-type ice-sheet surges are one of the prominent signals of glacial climate variability. They are characterised as abrupt, quasi-periodic episodes of ice-sheet instabilities during which large numbers of icebergs are released from the Laurentide ice sheet. The mechanisms controlling the timin...
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ftcopernicus:oai:publications.copernicus.org:egusphere103179 2023-05-15T16:39:36+02:00 Sensitivity of Heinrich-type ice-sheet surge characteristics to boundary forcing perturbations Schannwell, Clemens Mikolajewicz, Uwe Ziemen, Florian Kapsch, Marie-Luise 2023-01-23 application/pdf https://doi.org/10.5194/egusphere-2022-332 https://egusphere.copernicus.org/preprints/2022/egusphere-2022-332/ eng eng doi:10.5194/egusphere-2022-332 https://egusphere.copernicus.org/preprints/2022/egusphere-2022-332/ eISSN: Text 2023 ftcopernicus https://doi.org/10.5194/egusphere-2022-332 2023-01-30T17:22:43Z Heinrich-type ice-sheet surges are one of the prominent signals of glacial climate variability. They are characterised as abrupt, quasi-periodic episodes of ice-sheet instabilities during which large numbers of icebergs are released from the Laurentide ice sheet. The mechanisms controlling the timing and occurrence of Heinrich-type ice-sheet surges remain poorly constrained to this day. Here, we use a coupled ice sheet–solid Earth model to identify and quantify the importance of boundary forcing for the surge cycle length of Heinrich-type ice-sheet surges for two prominent ice streams of the Laurentide ice sheet – the land-terminating Mackenzie ice stream and the marine-terminating Hudson ice stream. Both ice streams show responses of similar magnitude to surface mass balance and geothermal heat flux perturbations, but Mackenzie ice stream is more sensitive to ice surface temperature perturbations, a fact likely caused by the warmer climate in this region. Ocean and sea-level forcing as well as different frequencies of the same forcing have a negligible effect on the surge cycle length. The simulations also highlight the fact that only a certain parameter space exists under which ice-sheet oscillations can be maintained. Transitioning from an oscillatory state to a persistent ice streaming state can result in an ice volume loss of up to 30 % for the respective ice stream drainage basin under otherwise constant climate conditions. We show that Mackenzie ice stream is susceptible to undergoing such a transition in response to all tested positive climate perturbations. This underlines the potential of the Mackenzie region to have contributed to prominent abrupt climate change events of the last deglaciation. Text Ice Sheet Copernicus Publications: E-Journals Hudson |
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Copernicus Publications: E-Journals |
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English |
description |
Heinrich-type ice-sheet surges are one of the prominent signals of glacial climate variability. They are characterised as abrupt, quasi-periodic episodes of ice-sheet instabilities during which large numbers of icebergs are released from the Laurentide ice sheet. The mechanisms controlling the timing and occurrence of Heinrich-type ice-sheet surges remain poorly constrained to this day. Here, we use a coupled ice sheet–solid Earth model to identify and quantify the importance of boundary forcing for the surge cycle length of Heinrich-type ice-sheet surges for two prominent ice streams of the Laurentide ice sheet – the land-terminating Mackenzie ice stream and the marine-terminating Hudson ice stream. Both ice streams show responses of similar magnitude to surface mass balance and geothermal heat flux perturbations, but Mackenzie ice stream is more sensitive to ice surface temperature perturbations, a fact likely caused by the warmer climate in this region. Ocean and sea-level forcing as well as different frequencies of the same forcing have a negligible effect on the surge cycle length. The simulations also highlight the fact that only a certain parameter space exists under which ice-sheet oscillations can be maintained. Transitioning from an oscillatory state to a persistent ice streaming state can result in an ice volume loss of up to 30 % for the respective ice stream drainage basin under otherwise constant climate conditions. We show that Mackenzie ice stream is susceptible to undergoing such a transition in response to all tested positive climate perturbations. This underlines the potential of the Mackenzie region to have contributed to prominent abrupt climate change events of the last deglaciation. |
format |
Text |
author |
Schannwell, Clemens Mikolajewicz, Uwe Ziemen, Florian Kapsch, Marie-Luise |
spellingShingle |
Schannwell, Clemens Mikolajewicz, Uwe Ziemen, Florian Kapsch, Marie-Luise Sensitivity of Heinrich-type ice-sheet surge characteristics to boundary forcing perturbations |
author_facet |
Schannwell, Clemens Mikolajewicz, Uwe Ziemen, Florian Kapsch, Marie-Luise |
author_sort |
Schannwell, Clemens |
title |
Sensitivity of Heinrich-type ice-sheet surge characteristics to boundary forcing perturbations |
title_short |
Sensitivity of Heinrich-type ice-sheet surge characteristics to boundary forcing perturbations |
title_full |
Sensitivity of Heinrich-type ice-sheet surge characteristics to boundary forcing perturbations |
title_fullStr |
Sensitivity of Heinrich-type ice-sheet surge characteristics to boundary forcing perturbations |
title_full_unstemmed |
Sensitivity of Heinrich-type ice-sheet surge characteristics to boundary forcing perturbations |
title_sort |
sensitivity of heinrich-type ice-sheet surge characteristics to boundary forcing perturbations |
publishDate |
2023 |
url |
https://doi.org/10.5194/egusphere-2022-332 https://egusphere.copernicus.org/preprints/2022/egusphere-2022-332/ |
geographic |
Hudson |
geographic_facet |
Hudson |
genre |
Ice Sheet |
genre_facet |
Ice Sheet |
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eISSN: |
op_relation |
doi:10.5194/egusphere-2022-332 https://egusphere.copernicus.org/preprints/2022/egusphere-2022-332/ |
op_doi |
https://doi.org/10.5194/egusphere-2022-332 |
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1766029932011454464 |