The 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 CO2 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...
Main Authors: | , , , , , , , , , |
---|---|
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
2020
|
Subjects: | |
Online Access: | http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/319017 https://dipot.ulb.ac.be/dspace/bitstream/2013/319017/3/Sigman_et_al_2021.pdf |
id |
ftunivbruxelles:oai:dipot.ulb.ac.be:2013/319017 |
---|---|
record_format |
openpolar |
spelling |
ftunivbruxelles:oai:dipot.ulb.ac.be:2013/319017 2023-05-15T13:54:45+02:00 The Southern Ocean during the ice ages: A review of the Antarctic surface isolation hypothesis, with comparison to the North Pacific Sigman, Daniel D.M. Fripiat, François Studer, Anja S. Kemeny, P. C. Martínez-García, Alfredo Hain, Mathis M.P. Ai, Xuyuan Wang, Xingchen Ren, Haojia Haug, Gerald H. 2020-12-26 1 full-text file(s): application/pdf http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/319017 https://dipot.ulb.ac.be/dspace/bitstream/2013/319017/3/Sigman_et_al_2021.pdf en eng uri/info:doi/10.1016/j.quascirev.2020.106732 uri/info:pii/S0277379120306946 uri/info:scp/85098498882 https://dipot.ulb.ac.be/dspace/bitstream/2013/319017/3/Sigman_et_al_2021.pdf http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/319017 1 full-text file(s): info:eu-repo/semantics/openAccess Quaternary science reviews, 254 Sciences exactes et naturelles Atmospheric CO2 Biological pump Ice ages Nitrogen North Pacific Ocean circulation Paleoceanography Paleoclimatology Pleistocene Southern Ocean Stable isotopes info:eu-repo/semantics/article info:ulb-repo/semantics/articlePeerReview info:ulb-repo/semantics/openurl/article 2020 ftunivbruxelles 2022-06-12T21:59:48Z The Southern Ocean is widely recognized as a potential cause of the lower atmospheric concentration of CO2 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 CO2 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 CO2 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 observations. ... Article in Journal/Newspaper Antarc* Antarctic Southern Ocean Subarctic DI-fusion : dépôt institutionnel de l'Université libre de Bruxelles (ULB) Antarctic Pacific Southern Ocean The Antarctic |
institution |
Open Polar |
collection |
DI-fusion : dépôt institutionnel de l'Université libre de Bruxelles (ULB) |
op_collection_id |
ftunivbruxelles |
language |
English |
topic |
Sciences exactes et naturelles Atmospheric CO2 Biological pump Ice ages Nitrogen North Pacific Ocean circulation Paleoceanography Paleoclimatology Pleistocene Southern Ocean Stable isotopes |
spellingShingle |
Sciences exactes et naturelles Atmospheric CO2 Biological pump Ice ages Nitrogen North Pacific Ocean circulation Paleoceanography Paleoclimatology Pleistocene Southern Ocean Stable isotopes Sigman, Daniel D.M. Fripiat, François Studer, Anja S. Kemeny, P. C. Martínez-García, Alfredo Hain, Mathis M.P. Ai, Xuyuan Wang, Xingchen Ren, Haojia Haug, Gerald H. The Southern Ocean during the ice ages: A review of the Antarctic surface isolation hypothesis, with comparison to the North Pacific |
topic_facet |
Sciences exactes et naturelles Atmospheric CO2 Biological pump Ice ages Nitrogen North Pacific Ocean circulation Paleoceanography Paleoclimatology Pleistocene Southern Ocean Stable isotopes |
description |
The Southern Ocean is widely recognized as a potential cause of the lower atmospheric concentration of CO2 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 CO2 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 CO2 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 observations. ... |
format |
Article in Journal/Newspaper |
author |
Sigman, Daniel D.M. Fripiat, François Studer, Anja S. Kemeny, P. C. Martínez-García, Alfredo Hain, Mathis M.P. Ai, Xuyuan Wang, Xingchen Ren, Haojia Haug, Gerald H. |
author_facet |
Sigman, Daniel D.M. Fripiat, François Studer, Anja S. Kemeny, P. C. Martínez-García, Alfredo Hain, Mathis M.P. Ai, Xuyuan Wang, Xingchen Ren, Haojia Haug, Gerald H. |
author_sort |
Sigman, Daniel D.M. |
title |
The Southern Ocean during the ice ages: A review of the Antarctic surface isolation hypothesis, with comparison to the North Pacific |
title_short |
The Southern Ocean during the ice ages: A review of the Antarctic surface isolation hypothesis, with comparison to the North Pacific |
title_full |
The Southern Ocean during the ice ages: A review of the Antarctic surface isolation hypothesis, with comparison to the North Pacific |
title_fullStr |
The Southern Ocean during the ice ages: A review of the Antarctic surface isolation hypothesis, with comparison to the North Pacific |
title_full_unstemmed |
The 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 |
publishDate |
2020 |
url |
http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/319017 https://dipot.ulb.ac.be/dspace/bitstream/2013/319017/3/Sigman_et_al_2021.pdf |
geographic |
Antarctic Pacific Southern Ocean The Antarctic |
geographic_facet |
Antarctic Pacific Southern Ocean The Antarctic |
genre |
Antarc* Antarctic Southern Ocean Subarctic |
genre_facet |
Antarc* Antarctic Southern Ocean Subarctic |
op_source |
Quaternary science reviews, 254 |
op_relation |
uri/info:doi/10.1016/j.quascirev.2020.106732 uri/info:pii/S0277379120306946 uri/info:scp/85098498882 https://dipot.ulb.ac.be/dspace/bitstream/2013/319017/3/Sigman_et_al_2021.pdf http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/319017 |
op_rights |
1 full-text file(s): info:eu-repo/semantics/openAccess |
_version_ |
1766260859200339968 |