Early deglacial Atlantic overturning decline and its role in atmospheric CO 2 rise inferred from carbon isotopes (δ 13 C)
The reason for the initial rise in atmospheric CO 2 during the last deglaciation remains unknown. Most recent hypotheses invoke Southern Hemisphere processes such as shifts in midlatitude westerly winds. Coeval changes in the Atlantic meridional overturning circulation (AMOC) are poorly quantified,...
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ftdoajarticles:oai:doaj.org/article:7af261af795642edb9f32d3e3e89eef8 2023-05-15T16:39:05+02:00 Early deglacial Atlantic overturning decline and its role in atmospheric CO 2 rise inferred from carbon isotopes (δ 13 C) A. Schmittner D. C. Lund 2015-02-01T00:00:00Z https://doi.org/10.5194/cp-11-135-2015 https://doaj.org/article/7af261af795642edb9f32d3e3e89eef8 EN eng Copernicus Publications http://www.clim-past.net/11/135/2015/cp-11-135-2015.pdf https://doaj.org/toc/1814-9324 https://doaj.org/toc/1814-9332 1814-9324 1814-9332 doi:10.5194/cp-11-135-2015 https://doaj.org/article/7af261af795642edb9f32d3e3e89eef8 Climate of the Past, Vol 11, Iss 2, Pp 135-152 (2015) Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 article 2015 ftdoajarticles https://doi.org/10.5194/cp-11-135-2015 2022-12-31T03:34:36Z The reason for the initial rise in atmospheric CO 2 during the last deglaciation remains unknown. Most recent hypotheses invoke Southern Hemisphere processes such as shifts in midlatitude westerly winds. Coeval changes in the Atlantic meridional overturning circulation (AMOC) are poorly quantified, and their relation to the CO 2 increase is not understood. Here we compare simulations from a global, coupled climate–biogeochemistry model that includes a detailed representation of stable carbon isotopes (δ 13 C) with a synthesis of high-resolution δ 13 C reconstructions from deep-sea sediments and ice core data. In response to a prolonged AMOC shutdown initialized from a preindustrial state, modeled δ 13 C of dissolved inorganic carbon (δ 13 C DIC ) decreases in most of the surface ocean and the subsurface Atlantic, with largest amplitudes (more than 1.5‰) in the intermediate-depth North Atlantic. It increases in the intermediate and abyssal South Atlantic, as well as in the subsurface Southern, Indian, and Pacific oceans. The modeled pattern is similar and highly correlated with the available foraminiferal δ 13 C reconstructions spanning from the late Last Glacial Maximum (LGM, ~19.5–18.5 ka BP) to the late Heinrich stadial event 1 (HS1, ~16.5–15.5 ka BP), but the model overestimates δ 13 C DIC reductions in the North Atlantic. Possible reasons for the model–sediment-data differences are discussed. Changes in remineralized δ 13 C DIC dominate the total δ 13 C DIC variations in the model but preformed contributions are not negligible. Simulated changes in atmospheric CO 2 and its isotopic composition (δ 13 C CO 2 ) agree well with ice core data. Modeled effects of AMOC-induced wind changes on the carbon and isotope cycles are small, suggesting that Southern Hemisphere westerly wind effects may have been less important for the global carbon cycle response during HS1 than previously thought. Our results indicate that during the early deglaciation the AMOC decreased for several thousand years. We propose that the ... Article in Journal/Newspaper ice core North Atlantic Directory of Open Access Journals: DOAJ Articles Pacific Indian Climate of the Past 11 2 135 152 |
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English |
topic |
Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 |
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Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 A. Schmittner D. C. Lund Early deglacial Atlantic overturning decline and its role in atmospheric CO 2 rise inferred from carbon isotopes (δ 13 C) |
topic_facet |
Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 |
description |
The reason for the initial rise in atmospheric CO 2 during the last deglaciation remains unknown. Most recent hypotheses invoke Southern Hemisphere processes such as shifts in midlatitude westerly winds. Coeval changes in the Atlantic meridional overturning circulation (AMOC) are poorly quantified, and their relation to the CO 2 increase is not understood. Here we compare simulations from a global, coupled climate–biogeochemistry model that includes a detailed representation of stable carbon isotopes (δ 13 C) with a synthesis of high-resolution δ 13 C reconstructions from deep-sea sediments and ice core data. In response to a prolonged AMOC shutdown initialized from a preindustrial state, modeled δ 13 C of dissolved inorganic carbon (δ 13 C DIC ) decreases in most of the surface ocean and the subsurface Atlantic, with largest amplitudes (more than 1.5‰) in the intermediate-depth North Atlantic. It increases in the intermediate and abyssal South Atlantic, as well as in the subsurface Southern, Indian, and Pacific oceans. The modeled pattern is similar and highly correlated with the available foraminiferal δ 13 C reconstructions spanning from the late Last Glacial Maximum (LGM, ~19.5–18.5 ka BP) to the late Heinrich stadial event 1 (HS1, ~16.5–15.5 ka BP), but the model overestimates δ 13 C DIC reductions in the North Atlantic. Possible reasons for the model–sediment-data differences are discussed. Changes in remineralized δ 13 C DIC dominate the total δ 13 C DIC variations in the model but preformed contributions are not negligible. Simulated changes in atmospheric CO 2 and its isotopic composition (δ 13 C CO 2 ) agree well with ice core data. Modeled effects of AMOC-induced wind changes on the carbon and isotope cycles are small, suggesting that Southern Hemisphere westerly wind effects may have been less important for the global carbon cycle response during HS1 than previously thought. Our results indicate that during the early deglaciation the AMOC decreased for several thousand years. We propose that the ... |
format |
Article in Journal/Newspaper |
author |
A. Schmittner D. C. Lund |
author_facet |
A. Schmittner D. C. Lund |
author_sort |
A. Schmittner |
title |
Early deglacial Atlantic overturning decline and its role in atmospheric CO 2 rise inferred from carbon isotopes (δ 13 C) |
title_short |
Early deglacial Atlantic overturning decline and its role in atmospheric CO 2 rise inferred from carbon isotopes (δ 13 C) |
title_full |
Early deglacial Atlantic overturning decline and its role in atmospheric CO 2 rise inferred from carbon isotopes (δ 13 C) |
title_fullStr |
Early deglacial Atlantic overturning decline and its role in atmospheric CO 2 rise inferred from carbon isotopes (δ 13 C) |
title_full_unstemmed |
Early deglacial Atlantic overturning decline and its role in atmospheric CO 2 rise inferred from carbon isotopes (δ 13 C) |
title_sort |
early deglacial atlantic overturning decline and its role in atmospheric co 2 rise inferred from carbon isotopes (δ 13 c) |
publisher |
Copernicus Publications |
publishDate |
2015 |
url |
https://doi.org/10.5194/cp-11-135-2015 https://doaj.org/article/7af261af795642edb9f32d3e3e89eef8 |
geographic |
Pacific Indian |
geographic_facet |
Pacific Indian |
genre |
ice core North Atlantic |
genre_facet |
ice core North Atlantic |
op_source |
Climate of the Past, Vol 11, Iss 2, Pp 135-152 (2015) |
op_relation |
http://www.clim-past.net/11/135/2015/cp-11-135-2015.pdf https://doaj.org/toc/1814-9324 https://doaj.org/toc/1814-9332 1814-9324 1814-9332 doi:10.5194/cp-11-135-2015 https://doaj.org/article/7af261af795642edb9f32d3e3e89eef8 |
op_doi |
https://doi.org/10.5194/cp-11-135-2015 |
container_title |
Climate of the Past |
container_volume |
11 |
container_issue |
2 |
container_start_page |
135 |
op_container_end_page |
152 |
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1766029416940437504 |