Iberian Margin Paleotemperatures and the Bipolar Seesaw
Présentation orale sur invitation / Invited oral presentation International audience The last glacial cycle provides the opportunity to investigate large changes in the Atlantic Meridional Overturning Circulation (AMOC) beyond the small fluctuations evidenced from modern measurements. Paleotemperatu...
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ftccsdartic:oai:HAL:hal-04370031v1 2024-02-11T10:04:17+01:00 Iberian Margin Paleotemperatures and the Bipolar Seesaw Davtian, Nina Bard, Edouard Collège de France - Chaire Evolution du climat et de l'océan 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)-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) Institut de Ciencia i Tecnologia Ambientals (ICTA) Universitat Autònoma de Barcelona (UAB) San Francisco (CA), United States 2023-12-11 https://hal.science/hal-04370031 en eng HAL CCSD American Geophysical Union hal-04370031 https://hal.science/hal-04370031 AGU23 https://hal.science/hal-04370031 AGU23, Dec 2023, San Francisco (CA), United States. pp.PP41A-03 [SDU]Sciences of the Universe [physics] [PHYS]Physics [physics] [SDE]Environmental Sciences info:eu-repo/semantics/conferenceObject Conference papers 2023 ftccsdartic 2024-01-13T23:43:36Z Présentation orale sur invitation / Invited oral presentation International audience The last glacial cycle provides the opportunity to investigate large changes in the Atlantic Meridional Overturning Circulation (AMOC) beyond the small fluctuations evidenced from modern measurements. Paleotemperature records from Greenland and the North Atlantic show an abrupt variability, called Dansgaard–Oeschger (DO) events, which is associated with abrupt changes of the AMOC. These DO events also have Southern Hemisphere counterparts via the thermal bipolar seesaw, a concept describing the meridional heat transport leading to asynchronous temperature changes between both hemispheres. However, temperature records from the North Atlantic show more pronounced DO cooling events during massive releases of icebergs known as Heinrich (H) events, contrary to ice-core–based temperature records from Greenland. Here, we present two high-resolution temperature records from the southern Iberian Margin, which are derived from two independent paleotemperature proxies (RI-OH′ and UK′37). Both temperature records from the southern Iberian Margin faithfully reflect the contrasting DO cooling amplitudes with and without H events. We show that temperature records from the southern Iberian Margin better support the classical thermal bipolar seesaw model than do ice-core–based temperature records from Greenland. We also introduce an extended thermal bipolar seesaw model that considers the contrasting DO cooling amplitudes with and without H events in the southern Iberian Margin, and a Bipolar Seesaw Index to discriminate DO cooling events with and without H events. Our data-model comparison emphasizes the role of the thermal bipolar seesaw in the abrupt temperature variability of both hemispheres with a clear enhancement during DO cooling events with H events, implying a relationship that is more complex than a simple flip-flop between two climate states linked to a tipping point threshold. Conference Object Greenland ice core North Atlantic Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) Greenland Flop ENVELOPE(-56.753,-56.753,-61.028,-61.028) |
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Open Polar |
collection |
Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) |
op_collection_id |
ftccsdartic |
language |
English |
topic |
[SDU]Sciences of the Universe [physics] [PHYS]Physics [physics] [SDE]Environmental Sciences |
spellingShingle |
[SDU]Sciences of the Universe [physics] [PHYS]Physics [physics] [SDE]Environmental Sciences Davtian, Nina Bard, Edouard Iberian Margin Paleotemperatures and the Bipolar Seesaw |
topic_facet |
[SDU]Sciences of the Universe [physics] [PHYS]Physics [physics] [SDE]Environmental Sciences |
description |
Présentation orale sur invitation / Invited oral presentation International audience The last glacial cycle provides the opportunity to investigate large changes in the Atlantic Meridional Overturning Circulation (AMOC) beyond the small fluctuations evidenced from modern measurements. Paleotemperature records from Greenland and the North Atlantic show an abrupt variability, called Dansgaard–Oeschger (DO) events, which is associated with abrupt changes of the AMOC. These DO events also have Southern Hemisphere counterparts via the thermal bipolar seesaw, a concept describing the meridional heat transport leading to asynchronous temperature changes between both hemispheres. However, temperature records from the North Atlantic show more pronounced DO cooling events during massive releases of icebergs known as Heinrich (H) events, contrary to ice-core–based temperature records from Greenland. Here, we present two high-resolution temperature records from the southern Iberian Margin, which are derived from two independent paleotemperature proxies (RI-OH′ and UK′37). Both temperature records from the southern Iberian Margin faithfully reflect the contrasting DO cooling amplitudes with and without H events. We show that temperature records from the southern Iberian Margin better support the classical thermal bipolar seesaw model than do ice-core–based temperature records from Greenland. We also introduce an extended thermal bipolar seesaw model that considers the contrasting DO cooling amplitudes with and without H events in the southern Iberian Margin, and a Bipolar Seesaw Index to discriminate DO cooling events with and without H events. Our data-model comparison emphasizes the role of the thermal bipolar seesaw in the abrupt temperature variability of both hemispheres with a clear enhancement during DO cooling events with H events, implying a relationship that is more complex than a simple flip-flop between two climate states linked to a tipping point threshold. |
author2 |
Collège de France - Chaire Evolution du climat et de l'océan 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)-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) Institut de Ciencia i Tecnologia Ambientals (ICTA) Universitat Autònoma de Barcelona (UAB) |
format |
Conference Object |
author |
Davtian, Nina Bard, Edouard |
author_facet |
Davtian, Nina Bard, Edouard |
author_sort |
Davtian, Nina |
title |
Iberian Margin Paleotemperatures and the Bipolar Seesaw |
title_short |
Iberian Margin Paleotemperatures and the Bipolar Seesaw |
title_full |
Iberian Margin Paleotemperatures and the Bipolar Seesaw |
title_fullStr |
Iberian Margin Paleotemperatures and the Bipolar Seesaw |
title_full_unstemmed |
Iberian Margin Paleotemperatures and the Bipolar Seesaw |
title_sort |
iberian margin paleotemperatures and the bipolar seesaw |
publisher |
HAL CCSD |
publishDate |
2023 |
url |
https://hal.science/hal-04370031 |
op_coverage |
San Francisco (CA), United States |
long_lat |
ENVELOPE(-56.753,-56.753,-61.028,-61.028) |
geographic |
Greenland Flop |
geographic_facet |
Greenland Flop |
genre |
Greenland ice core North Atlantic |
genre_facet |
Greenland ice core North Atlantic |
op_source |
AGU23 https://hal.science/hal-04370031 AGU23, Dec 2023, San Francisco (CA), United States. pp.PP41A-03 |
op_relation |
hal-04370031 https://hal.science/hal-04370031 |
_version_ |
1790600856999034880 |