Enhanced ocean oxygenation during Cenozoic warm periods
Dissolved oxygen (O2) is essential for most ocean ecosystems, fuelling organisms’ respiration and facilitating the cycling of carbon and nutrients. Oxygen measurements have been interpreted to indicate that the ocean’s oxygen-deficient zones (ODZs) are expanding under global warming. However, models...
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ftethz:oai:www.research-collection.ethz.ch:20.500.11850/569914 2023-05-15T18:25:40+02:00 Enhanced ocean oxygenation during Cenozoic warm periods Auderset, Alexandra Moretti, Simone Taphorn, Björn Ebner, Pia-Rebecca Kast, Emma Wang, Xingchen T. Schiebel, Ralf Sigman, Daniel M. Haug, Gerald H. Martínez-García, Alfredo 2022-09-01 application/application/pdf https://hdl.handle.net/20.500.11850/569914 https://doi.org/10.3929/ethz-b-000569914 en eng Nature info:eu-repo/semantics/altIdentifier/doi/10.1038/s41586-022-05017-0 info:eu-repo/semantics/altIdentifier/wos/000849436200012 http://hdl.handle.net/20.500.11850/569914 doi:10.3929/ethz-b-000569914 info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International Nature, 609 (7925) Biogeochemistry Palaeoceanography Palaeoclimate info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion 2022 ftethz https://doi.org/20.500.11850/56991410.3929/ethz-b-00056991410.1038/s41586-022-05017-0 2023-03-13T00:41:18Z Dissolved oxygen (O2) is essential for most ocean ecosystems, fuelling organisms’ respiration and facilitating the cycling of carbon and nutrients. Oxygen measurements have been interpreted to indicate that the ocean’s oxygen-deficient zones (ODZs) are expanding under global warming. However, models provide an unclear picture of future ODZ change in both the near term and the long term. The paleoclimate record can help explore the possible range of ODZ changes in warmer-than-modern periods. Here we use foraminifera-bound nitrogen (N) isotopes to show that water-column denitrification in the eastern tropical North Pacific was greatly reduced during the Middle Miocene Climatic Optimum (MMCO) and the Early Eocene Climatic Optimum (EECO). Because denitrification is restricted to oxygen-poor waters, our results indicate that, in these two Cenozoic periods of sustained warmth, ODZs were contracted, not expanded. ODZ contraction may have arisen from a decrease in upwelling-fuelled biological productivity in the tropical Pacific, which would have reduced oxygen demand in the subsurface. Alternatively, invigoration of deep-water ventilation by the Southern Ocean may have weakened the ocean’s ‘biological carbon pump’, which would have increased deep-ocean oxygen. The mechanism at play would have determined whether the ODZ contractions occurred in step with the warming or took centuries or millennia to develop. Thus, although our results from the Cenozoic do not necessarily apply to the near-term future, they might imply that global warming may eventually cause ODZ contraction. ISSN:0028-0836 ISSN:1476-4687 Article in Journal/Newspaper Southern Ocean ETH Zürich Research Collection Pacific Southern Ocean |
institution |
Open Polar |
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ETH Zürich Research Collection |
op_collection_id |
ftethz |
language |
English |
topic |
Biogeochemistry Palaeoceanography Palaeoclimate |
spellingShingle |
Biogeochemistry Palaeoceanography Palaeoclimate Auderset, Alexandra Moretti, Simone Taphorn, Björn Ebner, Pia-Rebecca Kast, Emma Wang, Xingchen T. Schiebel, Ralf Sigman, Daniel M. Haug, Gerald H. Martínez-García, Alfredo Enhanced ocean oxygenation during Cenozoic warm periods |
topic_facet |
Biogeochemistry Palaeoceanography Palaeoclimate |
description |
Dissolved oxygen (O2) is essential for most ocean ecosystems, fuelling organisms’ respiration and facilitating the cycling of carbon and nutrients. Oxygen measurements have been interpreted to indicate that the ocean’s oxygen-deficient zones (ODZs) are expanding under global warming. However, models provide an unclear picture of future ODZ change in both the near term and the long term. The paleoclimate record can help explore the possible range of ODZ changes in warmer-than-modern periods. Here we use foraminifera-bound nitrogen (N) isotopes to show that water-column denitrification in the eastern tropical North Pacific was greatly reduced during the Middle Miocene Climatic Optimum (MMCO) and the Early Eocene Climatic Optimum (EECO). Because denitrification is restricted to oxygen-poor waters, our results indicate that, in these two Cenozoic periods of sustained warmth, ODZs were contracted, not expanded. ODZ contraction may have arisen from a decrease in upwelling-fuelled biological productivity in the tropical Pacific, which would have reduced oxygen demand in the subsurface. Alternatively, invigoration of deep-water ventilation by the Southern Ocean may have weakened the ocean’s ‘biological carbon pump’, which would have increased deep-ocean oxygen. The mechanism at play would have determined whether the ODZ contractions occurred in step with the warming or took centuries or millennia to develop. Thus, although our results from the Cenozoic do not necessarily apply to the near-term future, they might imply that global warming may eventually cause ODZ contraction. ISSN:0028-0836 ISSN:1476-4687 |
format |
Article in Journal/Newspaper |
author |
Auderset, Alexandra Moretti, Simone Taphorn, Björn Ebner, Pia-Rebecca Kast, Emma Wang, Xingchen T. Schiebel, Ralf Sigman, Daniel M. Haug, Gerald H. Martínez-García, Alfredo |
author_facet |
Auderset, Alexandra Moretti, Simone Taphorn, Björn Ebner, Pia-Rebecca Kast, Emma Wang, Xingchen T. Schiebel, Ralf Sigman, Daniel M. Haug, Gerald H. Martínez-García, Alfredo |
author_sort |
Auderset, Alexandra |
title |
Enhanced ocean oxygenation during Cenozoic warm periods |
title_short |
Enhanced ocean oxygenation during Cenozoic warm periods |
title_full |
Enhanced ocean oxygenation during Cenozoic warm periods |
title_fullStr |
Enhanced ocean oxygenation during Cenozoic warm periods |
title_full_unstemmed |
Enhanced ocean oxygenation during Cenozoic warm periods |
title_sort |
enhanced ocean oxygenation during cenozoic warm periods |
publisher |
Nature |
publishDate |
2022 |
url |
https://hdl.handle.net/20.500.11850/569914 https://doi.org/10.3929/ethz-b-000569914 |
geographic |
Pacific Southern Ocean |
geographic_facet |
Pacific Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
Nature, 609 (7925) |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1038/s41586-022-05017-0 info:eu-repo/semantics/altIdentifier/wos/000849436200012 http://hdl.handle.net/20.500.11850/569914 doi:10.3929/ethz-b-000569914 |
op_rights |
info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International |
op_doi |
https://doi.org/20.500.11850/56991410.3929/ethz-b-00056991410.1038/s41586-022-05017-0 |
_version_ |
1766207256843517952 |