Changes in the geometry and strength of the Atlantic meridional overturning circulation during the last glacial (20–50 ka)

• Published in: Climate of the Past
• Main Authors: Burckel, Pierre, Waelbroeck, Claire, Luo, Yiming, Roche, Didier M., Pichat, Sylvain, Jaccard, Samuel L., Gherardi, Jeanne, Govin, Aline, Lippold, Jörg, Thil, François
• Other Authors: Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Paléocéanographie (PALEOCEAN), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Department of Oceanography Halifax (DO), Dalhousie University Halifax, Vrije Universiteit Amsterdam Amsterdam (VU), Modélisation du climat (CLIM), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement Lyon (LGL-TPE), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Oeschger Centre for Climate Change Research (OCCR), University of Bern, Glaces et Continents, Climats et Isotopes Stables (GLACCIOS), Climat et Magnétisme (CLIMAG), Géochrononologie Traceurs Archéométrie (GEOTRAC)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2016
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; Antarctic; Greenland; Antarc*; NADW; North Atlantic Deep Water; North Atlantic
• Online Access: https://hal.archives-ouvertes.fr/hal-01587574; https://hal.archives-ouvertes.fr/hal-01587574/document; https://hal.archives-ouvertes.fr/hal-01587574/file/cp-12-2061-2016.pdf; https://doi.org/10.5194/cp-12-2061-2016

International audience We reconstruct the geometry and strength of the Atlantic meridional overturning circulation during the Hein-rich stadial 2 and three Greenland interstadials of the 20– 50 ka period based on the comparison of new and published sedimentary 231 Pa / 230 Th data with simulated sedimentary 231 Pa / 230 Th. We show that the deep Atlantic circulation during these interstadials was very different from that of the Holocene. Northern-sourced waters likely circulated above 2500 m depth, with a flow rate lower than that of the present-day North Atlantic deep water (NADW). Southern-sourced deep waters most probably flowed northwards below 4000 m depth into the North Atlantic basin and then southwards as a return flow between 2500 and 4000 m depth. The flow rate of this southern-sourced deep water was likely larger than that of the modern Antarctic bottom water (AABW). Our results further show that during Heinrich stadial 2, the deep Atlantic was probably directly affected by a southern-sourced water mass below 2500 m depth, while a slow, southward-flowing water mass originating from the North Atlantic likely influenced depths between 1500 and 2500 m down to the equator.