Rapid shift and millennial-scale variations in Holocene North Pacific Intermediate Water ventilation
The Pacific hosts the largest oxygen minimum zones (OMZs) in the world ocean, which are thought to intensify and expand under future climate change, with significant consequences for marine ecosystems, biogeochemical cycles, and fisheries. At present, no deep ventilation occurs in the North Pacific...
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Online Access: | https://oceanrep.geomar.de/id/eprint/43032/ https://oceanrep.geomar.de/id/eprint/43032/7/5365.full.pdf https://doi.org/10.1073/pnas.1714754115 |
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ftoceanrep:oai:oceanrep.geomar.de:43032 2023-05-15T17:52:38+02:00 Rapid shift and millennial-scale variations in Holocene North Pacific Intermediate Water ventilation Lembke-Jene, Lester Tiedemann, Ralf Nürnberg, Dirk Gong, Xun Lohmann, Gerrit 2018-05-22 text https://oceanrep.geomar.de/id/eprint/43032/ https://oceanrep.geomar.de/id/eprint/43032/7/5365.full.pdf https://doi.org/10.1073/pnas.1714754115 en eng National Academy of Sciences https://oceanrep.geomar.de/id/eprint/43032/7/5365.full.pdf Lembke-Jene, L., Tiedemann, R., Nürnberg, D. , Gong, X. and Lohmann, G. (2018) Rapid shift and millennial-scale variations in Holocene North Pacific Intermediate Water ventilation. Open Access PNAS Proceedings of the National Academy of Sciences of the United States of America, 115 (21). pp. 5365-5370. DOI 10.1073/pnas.1714754115 <https://doi.org/10.1073/pnas.1714754115>. doi:10.1073/pnas.1714754115 cc_by_4.0 info:eu-repo/semantics/openAccess Article PeerReviewed 2018 ftoceanrep https://doi.org/10.1073/pnas.1714754115 2023-04-07T15:39:51Z The Pacific hosts the largest oxygen minimum zones (OMZs) in the world ocean, which are thought to intensify and expand under future climate change, with significant consequences for marine ecosystems, biogeochemical cycles, and fisheries. At present, no deep ventilation occurs in the North Pacific due to a persistent halocline, but relatively better-oxygenated subsurface North Pacific Intermediate Water (NPIW) mitigates OMZ development in lower latitudes. Over the past decades, instrumental data show decreasing oxygenation in NPIW; however, long-term variations in middepth ventilation are potentially large, obscuring anthropogenic influences against millennial-scale natural background shifts. Here, we use paleoceanographic proxy evidence from the Okhotsk Sea, the foremost North Pacific ventilation region, to show that its modern oxygenated pattern is a relatively recent feature, with little to no ventilation before six thousand years ago, constituting an apparent Early–Middle Holocene (EMH) threshold or “tipping point.” Complementary paleomodeling results likewise indicate a warmer, saltier EMH NPIW, different from its modern conditions. During the EMH, the Okhotsk Sea switched from a modern oxygenation source to a sink, through a combination of sea ice loss, higher water temperatures, and remineralization rates, inhibiting ventilation. We estimate a strongly decreased EMH NPIW oxygenation of ∼30 to 50%, and increased middepth Pacific nutrient concentrations and carbon storage. Our results (i) imply that under past or future warmer-than-present conditions, oceanic biogeochemical feedback mechanisms may change or even switch direction, and (ii) provide constraints on the high-latitude North Pacific’s influence on mesopelagic ventilation dynamics, with consequences for large oceanic regions. Article in Journal/Newspaper okhotsk sea Sea ice OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) Okhotsk Pacific Proceedings of the National Academy of Sciences 115 21 5365 5370 |
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Open Polar |
collection |
OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) |
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ftoceanrep |
language |
English |
description |
The Pacific hosts the largest oxygen minimum zones (OMZs) in the world ocean, which are thought to intensify and expand under future climate change, with significant consequences for marine ecosystems, biogeochemical cycles, and fisheries. At present, no deep ventilation occurs in the North Pacific due to a persistent halocline, but relatively better-oxygenated subsurface North Pacific Intermediate Water (NPIW) mitigates OMZ development in lower latitudes. Over the past decades, instrumental data show decreasing oxygenation in NPIW; however, long-term variations in middepth ventilation are potentially large, obscuring anthropogenic influences against millennial-scale natural background shifts. Here, we use paleoceanographic proxy evidence from the Okhotsk Sea, the foremost North Pacific ventilation region, to show that its modern oxygenated pattern is a relatively recent feature, with little to no ventilation before six thousand years ago, constituting an apparent Early–Middle Holocene (EMH) threshold or “tipping point.” Complementary paleomodeling results likewise indicate a warmer, saltier EMH NPIW, different from its modern conditions. During the EMH, the Okhotsk Sea switched from a modern oxygenation source to a sink, through a combination of sea ice loss, higher water temperatures, and remineralization rates, inhibiting ventilation. We estimate a strongly decreased EMH NPIW oxygenation of ∼30 to 50%, and increased middepth Pacific nutrient concentrations and carbon storage. Our results (i) imply that under past or future warmer-than-present conditions, oceanic biogeochemical feedback mechanisms may change or even switch direction, and (ii) provide constraints on the high-latitude North Pacific’s influence on mesopelagic ventilation dynamics, with consequences for large oceanic regions. |
format |
Article in Journal/Newspaper |
author |
Lembke-Jene, Lester Tiedemann, Ralf Nürnberg, Dirk Gong, Xun Lohmann, Gerrit |
spellingShingle |
Lembke-Jene, Lester Tiedemann, Ralf Nürnberg, Dirk Gong, Xun Lohmann, Gerrit Rapid shift and millennial-scale variations in Holocene North Pacific Intermediate Water ventilation |
author_facet |
Lembke-Jene, Lester Tiedemann, Ralf Nürnberg, Dirk Gong, Xun Lohmann, Gerrit |
author_sort |
Lembke-Jene, Lester |
title |
Rapid shift and millennial-scale variations in Holocene North Pacific Intermediate Water ventilation |
title_short |
Rapid shift and millennial-scale variations in Holocene North Pacific Intermediate Water ventilation |
title_full |
Rapid shift and millennial-scale variations in Holocene North Pacific Intermediate Water ventilation |
title_fullStr |
Rapid shift and millennial-scale variations in Holocene North Pacific Intermediate Water ventilation |
title_full_unstemmed |
Rapid shift and millennial-scale variations in Holocene North Pacific Intermediate Water ventilation |
title_sort |
rapid shift and millennial-scale variations in holocene north pacific intermediate water ventilation |
publisher |
National Academy of Sciences |
publishDate |
2018 |
url |
https://oceanrep.geomar.de/id/eprint/43032/ https://oceanrep.geomar.de/id/eprint/43032/7/5365.full.pdf https://doi.org/10.1073/pnas.1714754115 |
geographic |
Okhotsk Pacific |
geographic_facet |
Okhotsk Pacific |
genre |
okhotsk sea Sea ice |
genre_facet |
okhotsk sea Sea ice |
op_relation |
https://oceanrep.geomar.de/id/eprint/43032/7/5365.full.pdf Lembke-Jene, L., Tiedemann, R., Nürnberg, D. , Gong, X. and Lohmann, G. (2018) Rapid shift and millennial-scale variations in Holocene North Pacific Intermediate Water ventilation. Open Access PNAS Proceedings of the National Academy of Sciences of the United States of America, 115 (21). pp. 5365-5370. DOI 10.1073/pnas.1714754115 <https://doi.org/10.1073/pnas.1714754115>. doi:10.1073/pnas.1714754115 |
op_rights |
cc_by_4.0 info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.1073/pnas.1714754115 |
container_title |
Proceedings of the National Academy of Sciences |
container_volume |
115 |
container_issue |
21 |
container_start_page |
5365 |
op_container_end_page |
5370 |
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1766160314160644096 |