Asynchronous warming and δ18O evolution of deep Atlantic water masses during the last deglaciation
The large-scale reorganization of deep ocean circulation in the Atlantic involving changes in North Atlantic Deep Water (NADW) and Antarctic Bottom Water (AABW) played a critical role in regulating hemispheric and global climate during the last deglaciation. However, changes in the relative contribu...
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Online Access: | https://doi.org/10.1073/pnas.1704512114 |
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ftncar:oai:drupal-site.org:articles_21121 2023-09-05T13:12:12+02:00 Asynchronous warming and δ18O evolution of deep Atlantic water masses during the last deglaciation Zhang, Jiaxu (author) Liu, Zhengyu (author) Brady, Esther C. (author) Oppo, Delia W. (author) Clark, Peter U. (author) Jahn, Alexandra (author) Marcott, Shaun A. (author) Lindsay, Keith (author) 2017-10-02 https://doi.org/10.1073/pnas.1704512114 en eng Proceedings of the National Academy of Sciences--Proc Natl Acad Sci USA--0027-8424--1091-6490 articles:21121 ark:/85065/d7w66p9v doi:10.1073/pnas.1704512114 Copyright 2017 Author(s). Published under license by the National Academy of Sciences. article Text 2017 ftncar https://doi.org/10.1073/pnas.1704512114 2023-08-14T18:47:49Z The large-scale reorganization of deep ocean circulation in the Atlantic involving changes in North Atlantic Deep Water (NADW) and Antarctic Bottom Water (AABW) played a critical role in regulating hemispheric and global climate during the last deglaciation. However, changes in the relative contributions of NADW and AABW and their properties are poorly constrained by marine records, including delta O-18 of benthic foraminiferal calcite (delta O-18(c)) . Here, we use an isotope-enabled ocean general circulation model with realistic geometry and forcing conditions to simulate the deglacial water mass and delta O-18 evolution. Model results suggest that, in response to North Atlantic freshwater forcing during the early phase of the last deglaciation, NADW nearly collapses, while AABW mildly weakens. Rather than reflecting changes in NADW or AABW properties caused by freshwater input as suggested previously, the observed phasing difference of deep delta O-18(c) likely reflects early warming of the deep northern North Atlantic by similar to 1.4 degrees C, while deep Southern Ocean temperature remains largely unchanged. We propose a thermodynamic mechanism to explain the early warming in the North Atlantic, featuring a strong middepth warming and enhanced downward heat flux via vertical mixing. Our results emphasize that the way that ocean circulation affects heat, a dynamic tracer, is considerably different from how it affects passive tracers, like delta O-18, and call for caution when inferring water mass changes from delta O-18(c) records while assuming uniform changes in deep temperatures. DE-SC0006744 Article in Journal/Newspaper Antarc* Antarctic NADW North Atlantic Deep Water North Atlantic Southern Ocean OpenSky (NCAR/UCAR - National Center for Atmospheric Research/University Corporation for Atmospheric Research) Antarctic Southern Ocean Proceedings of the National Academy of Sciences 114 42 11075 11080 |
institution |
Open Polar |
collection |
OpenSky (NCAR/UCAR - National Center for Atmospheric Research/University Corporation for Atmospheric Research) |
op_collection_id |
ftncar |
language |
English |
description |
The large-scale reorganization of deep ocean circulation in the Atlantic involving changes in North Atlantic Deep Water (NADW) and Antarctic Bottom Water (AABW) played a critical role in regulating hemispheric and global climate during the last deglaciation. However, changes in the relative contributions of NADW and AABW and their properties are poorly constrained by marine records, including delta O-18 of benthic foraminiferal calcite (delta O-18(c)) . Here, we use an isotope-enabled ocean general circulation model with realistic geometry and forcing conditions to simulate the deglacial water mass and delta O-18 evolution. Model results suggest that, in response to North Atlantic freshwater forcing during the early phase of the last deglaciation, NADW nearly collapses, while AABW mildly weakens. Rather than reflecting changes in NADW or AABW properties caused by freshwater input as suggested previously, the observed phasing difference of deep delta O-18(c) likely reflects early warming of the deep northern North Atlantic by similar to 1.4 degrees C, while deep Southern Ocean temperature remains largely unchanged. We propose a thermodynamic mechanism to explain the early warming in the North Atlantic, featuring a strong middepth warming and enhanced downward heat flux via vertical mixing. Our results emphasize that the way that ocean circulation affects heat, a dynamic tracer, is considerably different from how it affects passive tracers, like delta O-18, and call for caution when inferring water mass changes from delta O-18(c) records while assuming uniform changes in deep temperatures. DE-SC0006744 |
author2 |
Zhang, Jiaxu (author) Liu, Zhengyu (author) Brady, Esther C. (author) Oppo, Delia W. (author) Clark, Peter U. (author) Jahn, Alexandra (author) Marcott, Shaun A. (author) Lindsay, Keith (author) |
format |
Article in Journal/Newspaper |
title |
Asynchronous warming and δ18O evolution of deep Atlantic water masses during the last deglaciation |
spellingShingle |
Asynchronous warming and δ18O evolution of deep Atlantic water masses during the last deglaciation |
title_short |
Asynchronous warming and δ18O evolution of deep Atlantic water masses during the last deglaciation |
title_full |
Asynchronous warming and δ18O evolution of deep Atlantic water masses during the last deglaciation |
title_fullStr |
Asynchronous warming and δ18O evolution of deep Atlantic water masses during the last deglaciation |
title_full_unstemmed |
Asynchronous warming and δ18O evolution of deep Atlantic water masses during the last deglaciation |
title_sort |
asynchronous warming and δ18o evolution of deep atlantic water masses during the last deglaciation |
publishDate |
2017 |
url |
https://doi.org/10.1073/pnas.1704512114 |
geographic |
Antarctic Southern Ocean |
geographic_facet |
Antarctic Southern Ocean |
genre |
Antarc* Antarctic NADW North Atlantic Deep Water North Atlantic Southern Ocean |
genre_facet |
Antarc* Antarctic NADW North Atlantic Deep Water North Atlantic Southern Ocean |
op_relation |
Proceedings of the National Academy of Sciences--Proc Natl Acad Sci USA--0027-8424--1091-6490 articles:21121 ark:/85065/d7w66p9v doi:10.1073/pnas.1704512114 |
op_rights |
Copyright 2017 Author(s). Published under license by the National Academy of Sciences. |
op_doi |
https://doi.org/10.1073/pnas.1704512114 |
container_title |
Proceedings of the National Academy of Sciences |
container_volume |
114 |
container_issue |
42 |
container_start_page |
11075 |
op_container_end_page |
11080 |
_version_ |
1776199354078461952 |