Southern Ocean during the ice ages: A review of the Antarctic surface isolation hypothesis, with comparison to the North Pacific
The Southern Ocean is widely recognized as a potential cause of the lower atmospheric concentration of COâ‚‚ during ice ages, but the mechanism is debated. Focusing on the Southern Ocean surface, we review biogeochemical paleoproxy data and carbon cycle concepts that together favor the view that bot...
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ftcaltechauth:oai:authors.library.caltech.edu:jezxk-hzh35 2024-10-13T14:02:30+00:00 Southern Ocean during the ice ages: A review of the Antarctic surface isolation hypothesis, with comparison to the North Pacific Sigman, Daniel M. Fripiat, François Studer, Anja S. Kemeny, Preston C. MartÃnez-GarcÃa, Alfredo Hain, Mathis P. Ai, Xuyuan Wang, Xingchen Ren, Haojia Haug, Gerald H. 2021-02-15 https://doi.org/10.1016/j.quascirev.2020.106732 unknown Elsevier https://doi.org/10.1016/j.quascirev.2020.106732 eprintid:108405 info:eu-repo/semantics/openAccess Other Quaternary Science Reviews, 254, Art. No. 106732, (2021-02-15) Paleoclimatology Paleoceanography Pleistocene Ice ages Stable isotopes Nitrogen Atmospheric CO2 Southern Ocean North Pacific Ocean circulation Biological pump info:eu-repo/semantics/article 2021 ftcaltechauth https://doi.org/10.1016/j.quascirev.2020.106732 2024-09-25T18:46:42Z The Southern Ocean is widely recognized as a potential cause of the lower atmospheric concentration of COâ‚‚ during ice ages, but the mechanism is debated. Focusing on the Southern Ocean surface, we review biogeochemical paleoproxy data and carbon cycle concepts that together favor the view that both the Antarctic and Subantarctic Zones (AZ and SAZ) of the Southern Ocean played roles in lowering ice age COâ‚‚ levels. In the SAZ, the data indicate dust-driven iron fertilization of phytoplankton growth during peak ice age conditions. In the ice age AZ, the area-normalized exchange of water between the surface and subsurface appears to have been reduced, a state that we summarize as "isolation" of the AZ surface. Under most scenarios, this change would have stemmed the leak of biologically stored COâ‚‚ that occurs in the AZ today. SAZ iron fertilization during the last ice age fits with our understanding of ocean processes as gleaned from modern field studies and experiments; indeed, this hypothesis was proposed prior to evidentiary support. In contrast, AZ surface isolation is neither intuitive nor spontaneously generated in climate model simulations of the last ice age. In a more prospective component of this review, the suggested causes for AZ surface isolation are considered in light of the subarctic North Pacific (SNP), where the paleoproxies of productivity and nutrient consumption indicate similar upper ocean biogeochemical changes over glacial cycles, although with different timings at deglaciation. Among the proposed initiators of glacial AZ surface isolation, a single mechanism is sought that can explain the changes in both the AZ and the SNP. The analysis favors a weakening and/or equatorward shift in the upwelling associated with the westerly winds, occurring in both hemispheres. This view is controversial, especially for the SNP, where there is evidence of enhanced upper water column ventilation during the last ice age. We offer an interpretation that may explain key aspects of the AZ and SNP ... Article in Journal/Newspaper Antarc* Antarctic Southern Ocean Subarctic Caltech Authors (California Institute of Technology) Antarctic Southern Ocean The Antarctic Pacific Quaternary Science Reviews 254 106732 |
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Open Polar |
collection |
Caltech Authors (California Institute of Technology) |
op_collection_id |
ftcaltechauth |
language |
unknown |
topic |
Paleoclimatology Paleoceanography Pleistocene Ice ages Stable isotopes Nitrogen Atmospheric CO2 Southern Ocean North Pacific Ocean circulation Biological pump |
spellingShingle |
Paleoclimatology Paleoceanography Pleistocene Ice ages Stable isotopes Nitrogen Atmospheric CO2 Southern Ocean North Pacific Ocean circulation Biological pump Sigman, Daniel M. Fripiat, François Studer, Anja S. Kemeny, Preston C. MartÃnez-GarcÃa, Alfredo Hain, Mathis P. Ai, Xuyuan Wang, Xingchen Ren, Haojia Haug, Gerald H. Southern Ocean during the ice ages: A review of the Antarctic surface isolation hypothesis, with comparison to the North Pacific |
topic_facet |
Paleoclimatology Paleoceanography Pleistocene Ice ages Stable isotopes Nitrogen Atmospheric CO2 Southern Ocean North Pacific Ocean circulation Biological pump |
description |
The Southern Ocean is widely recognized as a potential cause of the lower atmospheric concentration of COâ‚‚ during ice ages, but the mechanism is debated. Focusing on the Southern Ocean surface, we review biogeochemical paleoproxy data and carbon cycle concepts that together favor the view that both the Antarctic and Subantarctic Zones (AZ and SAZ) of the Southern Ocean played roles in lowering ice age COâ‚‚ levels. In the SAZ, the data indicate dust-driven iron fertilization of phytoplankton growth during peak ice age conditions. In the ice age AZ, the area-normalized exchange of water between the surface and subsurface appears to have been reduced, a state that we summarize as "isolation" of the AZ surface. Under most scenarios, this change would have stemmed the leak of biologically stored COâ‚‚ that occurs in the AZ today. SAZ iron fertilization during the last ice age fits with our understanding of ocean processes as gleaned from modern field studies and experiments; indeed, this hypothesis was proposed prior to evidentiary support. In contrast, AZ surface isolation is neither intuitive nor spontaneously generated in climate model simulations of the last ice age. In a more prospective component of this review, the suggested causes for AZ surface isolation are considered in light of the subarctic North Pacific (SNP), where the paleoproxies of productivity and nutrient consumption indicate similar upper ocean biogeochemical changes over glacial cycles, although with different timings at deglaciation. Among the proposed initiators of glacial AZ surface isolation, a single mechanism is sought that can explain the changes in both the AZ and the SNP. The analysis favors a weakening and/or equatorward shift in the upwelling associated with the westerly winds, occurring in both hemispheres. This view is controversial, especially for the SNP, where there is evidence of enhanced upper water column ventilation during the last ice age. We offer an interpretation that may explain key aspects of the AZ and SNP ... |
format |
Article in Journal/Newspaper |
author |
Sigman, Daniel M. Fripiat, François Studer, Anja S. Kemeny, Preston C. MartÃnez-GarcÃa, Alfredo Hain, Mathis P. Ai, Xuyuan Wang, Xingchen Ren, Haojia Haug, Gerald H. |
author_facet |
Sigman, Daniel M. Fripiat, François Studer, Anja S. Kemeny, Preston C. MartÃnez-GarcÃa, Alfredo Hain, Mathis P. Ai, Xuyuan Wang, Xingchen Ren, Haojia Haug, Gerald H. |
author_sort |
Sigman, Daniel M. |
title |
Southern Ocean during the ice ages: A review of the Antarctic surface isolation hypothesis, with comparison to the North Pacific |
title_short |
Southern Ocean during the ice ages: A review of the Antarctic surface isolation hypothesis, with comparison to the North Pacific |
title_full |
Southern Ocean during the ice ages: A review of the Antarctic surface isolation hypothesis, with comparison to the North Pacific |
title_fullStr |
Southern Ocean during the ice ages: A review of the Antarctic surface isolation hypothesis, with comparison to the North Pacific |
title_full_unstemmed |
Southern Ocean during the ice ages: A review of the Antarctic surface isolation hypothesis, with comparison to the North Pacific |
title_sort |
southern ocean during the ice ages: a review of the antarctic surface isolation hypothesis, with comparison to the north pacific |
publisher |
Elsevier |
publishDate |
2021 |
url |
https://doi.org/10.1016/j.quascirev.2020.106732 |
geographic |
Antarctic Southern Ocean The Antarctic Pacific |
geographic_facet |
Antarctic Southern Ocean The Antarctic Pacific |
genre |
Antarc* Antarctic Southern Ocean Subarctic |
genre_facet |
Antarc* Antarctic Southern Ocean Subarctic |
op_source |
Quaternary Science Reviews, 254, Art. No. 106732, (2021-02-15) |
op_relation |
https://doi.org/10.1016/j.quascirev.2020.106732 eprintid:108405 |
op_rights |
info:eu-repo/semantics/openAccess Other |
op_doi |
https://doi.org/10.1016/j.quascirev.2020.106732 |
container_title |
Quaternary Science Reviews |
container_volume |
254 |
container_start_page |
106732 |
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1812817839075098624 |