Poleward Shift in the Southern Hemisphere Westerly Winds Synchronous With the Deglacial Rise in CO2
The Southern Hemisphere westerly winds influence deep ocean circulation and carbon storage. While the westerlies are hypothesized to play a key role in regulating atmospheric CO2 over glacial-interglacial cycles, past changes in their position and strength remain poorly constrained. Here, we use a c...
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ftethz:oai:www.research-collection.ethz.ch:20.500.11850/621967 2023-12-03T10:30:11+01:00 Poleward Shift in the Southern Hemisphere Westerly Winds Synchronous With the Deglacial Rise in CO2 Gray, William R. de Lavergne, Casimir Jnglin Wills, Robert id_orcid:0 000-0002-7776-2076 Menviel, Laurie Spence, Paul Holzer, Mark Kageyama, Masa Michel, Elisabeth 2023-07 application/application/pdf https://hdl.handle.net/20.500.11850/621967 https://doi.org/10.3929/ethz-b-000621967 en eng Wiley info:eu-repo/semantics/altIdentifier/doi/10.1029/2023PA004666 info:eu-repo/semantics/altIdentifier/wos/001021050700001 http://hdl.handle.net/20.500.11850/621967 doi:10.3929/ethz-b-000621967 info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by-nc/4.0/ Creative Commons Attribution-NonCommercial 4.0 International Paleoceanography and Paleoclimatology, 38 (7) info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion 2023 ftethz https://doi.org/20.500.11850/62196710.3929/ethz-b-00062196710.1029/2023PA004666 2023-11-06T00:51:26Z The Southern Hemisphere westerly winds influence deep ocean circulation and carbon storage. While the westerlies are hypothesized to play a key role in regulating atmospheric CO2 over glacial-interglacial cycles, past changes in their position and strength remain poorly constrained. Here, we use a compilation of planktic foraminiferal δ18O from across the Southern Ocean and emergent relationships within an ensemble of climate models to reconstruct changes in the Southern Hemisphere surface westerlies over the last deglaciation. We infer a 4.8° (2.9–7.1°, 95% confidence interval) equatorward shift and about a 25% weakening of the westerlies during the Last Glacial Maximum (20 ka) relative to the mid-Holocene (6.5 ka). Climate models from the Palaeoclimate Modeling Intercomparison Project substantially underestimate this inferred equatorward wind shift. According to our reconstruction, the poleward shift in the westerlies over deglaciation closely mirrors the rise in atmospheric CO2 (R2 = 0.98). Experiments with a 0.25° resolution ocean-sea-ice-carbon model suggest that shifting the westerlies equatorward reduces the overturning rate of the ocean below 2 km depth, leading to a suppression of CO2 outgassing from the polar Southern Ocean. Our results support a role for the westerly winds in driving the deglacial CO2 rise, and suggest outgassing of natural CO2 from the Southern Ocean is likely to increase as the westerlies shift poleward due to anthropogenic warming. ISSN:2572-4525 ISSN:2572-4517 Article in Journal/Newspaper Sea ice Southern Ocean ETH Zürich Research Collection Southern Ocean |
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Open Polar |
collection |
ETH Zürich Research Collection |
op_collection_id |
ftethz |
language |
English |
description |
The Southern Hemisphere westerly winds influence deep ocean circulation and carbon storage. While the westerlies are hypothesized to play a key role in regulating atmospheric CO2 over glacial-interglacial cycles, past changes in their position and strength remain poorly constrained. Here, we use a compilation of planktic foraminiferal δ18O from across the Southern Ocean and emergent relationships within an ensemble of climate models to reconstruct changes in the Southern Hemisphere surface westerlies over the last deglaciation. We infer a 4.8° (2.9–7.1°, 95% confidence interval) equatorward shift and about a 25% weakening of the westerlies during the Last Glacial Maximum (20 ka) relative to the mid-Holocene (6.5 ka). Climate models from the Palaeoclimate Modeling Intercomparison Project substantially underestimate this inferred equatorward wind shift. According to our reconstruction, the poleward shift in the westerlies over deglaciation closely mirrors the rise in atmospheric CO2 (R2 = 0.98). Experiments with a 0.25° resolution ocean-sea-ice-carbon model suggest that shifting the westerlies equatorward reduces the overturning rate of the ocean below 2 km depth, leading to a suppression of CO2 outgassing from the polar Southern Ocean. Our results support a role for the westerly winds in driving the deglacial CO2 rise, and suggest outgassing of natural CO2 from the Southern Ocean is likely to increase as the westerlies shift poleward due to anthropogenic warming. ISSN:2572-4525 ISSN:2572-4517 |
format |
Article in Journal/Newspaper |
author |
Gray, William R. de Lavergne, Casimir Jnglin Wills, Robert id_orcid:0 000-0002-7776-2076 Menviel, Laurie Spence, Paul Holzer, Mark Kageyama, Masa Michel, Elisabeth |
spellingShingle |
Gray, William R. de Lavergne, Casimir Jnglin Wills, Robert id_orcid:0 000-0002-7776-2076 Menviel, Laurie Spence, Paul Holzer, Mark Kageyama, Masa Michel, Elisabeth Poleward Shift in the Southern Hemisphere Westerly Winds Synchronous With the Deglacial Rise in CO2 |
author_facet |
Gray, William R. de Lavergne, Casimir Jnglin Wills, Robert id_orcid:0 000-0002-7776-2076 Menviel, Laurie Spence, Paul Holzer, Mark Kageyama, Masa Michel, Elisabeth |
author_sort |
Gray, William R. |
title |
Poleward Shift in the Southern Hemisphere Westerly Winds Synchronous With the Deglacial Rise in CO2 |
title_short |
Poleward Shift in the Southern Hemisphere Westerly Winds Synchronous With the Deglacial Rise in CO2 |
title_full |
Poleward Shift in the Southern Hemisphere Westerly Winds Synchronous With the Deglacial Rise in CO2 |
title_fullStr |
Poleward Shift in the Southern Hemisphere Westerly Winds Synchronous With the Deglacial Rise in CO2 |
title_full_unstemmed |
Poleward Shift in the Southern Hemisphere Westerly Winds Synchronous With the Deglacial Rise in CO2 |
title_sort |
poleward shift in the southern hemisphere westerly winds synchronous with the deglacial rise in co2 |
publisher |
Wiley |
publishDate |
2023 |
url |
https://hdl.handle.net/20.500.11850/621967 https://doi.org/10.3929/ethz-b-000621967 |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Sea ice Southern Ocean |
genre_facet |
Sea ice Southern Ocean |
op_source |
Paleoceanography and Paleoclimatology, 38 (7) |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1029/2023PA004666 info:eu-repo/semantics/altIdentifier/wos/001021050700001 http://hdl.handle.net/20.500.11850/621967 doi:10.3929/ethz-b-000621967 |
op_rights |
info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by-nc/4.0/ Creative Commons Attribution-NonCommercial 4.0 International |
op_doi |
https://doi.org/20.500.11850/62196710.3929/ethz-b-00062196710.1029/2023PA004666 |
_version_ |
1784255884475498496 |