Weaker AMOC at the Last Glacial MaximumWeaker AMOC at the Last Glacial Maximum
International audience Despite its role in heat, salt, and nutrient transport, the state of the Atlantic MeridionalOverturning Circulation (AMOC) at the Last Glacial Maximum (LGM) is still debated. Here, using a carbon-isotope enabled Earth system model, we perform a series of LGM experiments in whi...
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ftccsdartic:oai:HAL:hal-03544786v1 2023-12-17T10:21:41+01:00 Weaker AMOC at the Last Glacial MaximumWeaker AMOC at the Last Glacial Maximum Menviel, Laurie Spence, Paul Skinner, Luke Kazuyo, Tachikawa Friedrich, Tobias Missiaen, Lise Yu, Jimin Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE) Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE) New Orleans and Online, United States 2021-12-13 https://hal.science/hal-03544786 en eng HAL CCSD hal-03544786 https://hal.science/hal-03544786 AGU fall meeting https://hal.science/hal-03544786 AGU fall meeting, Dec 2021, New Orleans and Online, United States [SDU.STU]Sciences of the Universe [physics]/Earth Sciences info:eu-repo/semantics/conferenceObject Conference papers 2021 ftccsdartic 2023-11-19T00:17:05Z International audience Despite its role in heat, salt, and nutrient transport, the state of the Atlantic MeridionalOverturning Circulation (AMOC) at the Last Glacial Maximum (LGM) is still debated. Here, using a carbon-isotope enabled Earth system model, we perform a series of LGM experiments in which the AMOC state is varied. The simulated phosphate, δ13C, ventilation age and eps(Nd) distributions are compared to available North Atlantic LGM records. We find that proxy records are consistent with a shallower and ∼50% weaker AMOC compared to PI. This is associated with a 3º equatorward shift of the sea ice edge and convection sites in the Norwegian Sea. The shoaling of North Atlantic Deep Waters (NADW) allows for an incursion of Antarctic Bottom Water (AABW) in the North Atlantic, despite a 40% weakening of AABW transport. While the Deep Western Boundary Current in the northwest Atlantic weakens with NADW, the mid-depth southward flow on the east side of the north Mid-Atlantic Ridge strengthens, consistent with paleo-records. This northeast Atlantic intensification is due to a change in density gradients: a weaker AMOC reduces the transport of equatorial waters to the northeast Atlantic, thus weakening the North Atlantic zonal density gradient. Such a weaker oceanic circulation at the LGM leads to an increase in deep ocean dissolved inorganic carbon (DIC) concentration, and thus a larger vertical DIC gradient, which would have contributed to lowering atmospheric CO2 concentration Conference Object Antarc* Antarctic NADW North Atlantic Northeast Atlantic Northwest Atlantic Norwegian Sea Sea ice Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) Antarctic Norwegian Sea Mid-Atlantic Ridge Orleans ENVELOPE(-60.667,-60.667,-63.950,-63.950) |
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Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) |
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ftccsdartic |
language |
English |
topic |
[SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
spellingShingle |
[SDU.STU]Sciences of the Universe [physics]/Earth Sciences Menviel, Laurie Spence, Paul Skinner, Luke Kazuyo, Tachikawa Friedrich, Tobias Missiaen, Lise Yu, Jimin Weaker AMOC at the Last Glacial MaximumWeaker AMOC at the Last Glacial Maximum |
topic_facet |
[SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
description |
International audience Despite its role in heat, salt, and nutrient transport, the state of the Atlantic MeridionalOverturning Circulation (AMOC) at the Last Glacial Maximum (LGM) is still debated. Here, using a carbon-isotope enabled Earth system model, we perform a series of LGM experiments in which the AMOC state is varied. The simulated phosphate, δ13C, ventilation age and eps(Nd) distributions are compared to available North Atlantic LGM records. We find that proxy records are consistent with a shallower and ∼50% weaker AMOC compared to PI. This is associated with a 3º equatorward shift of the sea ice edge and convection sites in the Norwegian Sea. The shoaling of North Atlantic Deep Waters (NADW) allows for an incursion of Antarctic Bottom Water (AABW) in the North Atlantic, despite a 40% weakening of AABW transport. While the Deep Western Boundary Current in the northwest Atlantic weakens with NADW, the mid-depth southward flow on the east side of the north Mid-Atlantic Ridge strengthens, consistent with paleo-records. This northeast Atlantic intensification is due to a change in density gradients: a weaker AMOC reduces the transport of equatorial waters to the northeast Atlantic, thus weakening the North Atlantic zonal density gradient. Such a weaker oceanic circulation at the LGM leads to an increase in deep ocean dissolved inorganic carbon (DIC) concentration, and thus a larger vertical DIC gradient, which would have contributed to lowering atmospheric CO2 concentration |
author2 |
Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE) Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE) |
format |
Conference Object |
author |
Menviel, Laurie Spence, Paul Skinner, Luke Kazuyo, Tachikawa Friedrich, Tobias Missiaen, Lise Yu, Jimin |
author_facet |
Menviel, Laurie Spence, Paul Skinner, Luke Kazuyo, Tachikawa Friedrich, Tobias Missiaen, Lise Yu, Jimin |
author_sort |
Menviel, Laurie |
title |
Weaker AMOC at the Last Glacial MaximumWeaker AMOC at the Last Glacial Maximum |
title_short |
Weaker AMOC at the Last Glacial MaximumWeaker AMOC at the Last Glacial Maximum |
title_full |
Weaker AMOC at the Last Glacial MaximumWeaker AMOC at the Last Glacial Maximum |
title_fullStr |
Weaker AMOC at the Last Glacial MaximumWeaker AMOC at the Last Glacial Maximum |
title_full_unstemmed |
Weaker AMOC at the Last Glacial MaximumWeaker AMOC at the Last Glacial Maximum |
title_sort |
weaker amoc at the last glacial maximumweaker amoc at the last glacial maximum |
publisher |
HAL CCSD |
publishDate |
2021 |
url |
https://hal.science/hal-03544786 |
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New Orleans and Online, United States |
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ENVELOPE(-60.667,-60.667,-63.950,-63.950) |
geographic |
Antarctic Norwegian Sea Mid-Atlantic Ridge Orleans |
geographic_facet |
Antarctic Norwegian Sea Mid-Atlantic Ridge Orleans |
genre |
Antarc* Antarctic NADW North Atlantic Northeast Atlantic Northwest Atlantic Norwegian Sea Sea ice |
genre_facet |
Antarc* Antarctic NADW North Atlantic Northeast Atlantic Northwest Atlantic Norwegian Sea Sea ice |
op_source |
AGU fall meeting https://hal.science/hal-03544786 AGU fall meeting, Dec 2021, New Orleans and Online, United States |
op_relation |
hal-03544786 https://hal.science/hal-03544786 |
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1785537596298887168 |