Enhanced Atlantic Meridional Overturning Circulation supports the Last Glacial Inception

• Published in: Quaternary Science Reviews
• Main Authors: Guihou, Abel, Pichat, Sylvain, Govin, Aline, Nave, Silvia, Michel, Elisabeth, Duplessy, Jean-Claude, Telouk, Philippe, Labeyrie, Laurent
• Other Authors: Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Climat et Magnétisme (CLIMAG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Paléocéanographie (PALEOCEAN), Institut Universitaire de France, CEA, CNRS, UVSQ ENS Lyon, Universite de Lyon, INSU-CNRS PNEDC, INSU-CNRS, Past4Future, FCT : 06-EuroMARC-FP-008, EUROMARC/0002/2007, GRICES/CNRS
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2011
• Subjects: Paleoceanography; AMOC; Glacial inception; Last Interglacial; 231Pa/230Th; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Ice Sheet; north atlantic current; North Atlantic
• Online Access: https://insu.hal.science/insu-00683865; https://doi.org/10.1016/j.quascirev.2011.03.017

International audience The Atlantic Meridional Overturning Circulation (AMOC) is a key feature of the climate system. However, its role during climate change is still poorly constrained particularly during an Interglacial to Glacial climate transition and the associated global cooling. We present here the first reconstruction of the evolution of the vertical structure of the rate of the AMOC from the Last Interglaciation to the subsequent glaciation (128,000-60,000 years ago) based on sedimentary ((231)Pa/(230)Th) records. We show a deep AMOC during the interglacial warmth Marine Isotope Stage (MIS) 5.5 and a shallower glacial one during glacial MIS 4. The change between these two patterns occurred mostly during the glacial inception, i.e. the transition from MIS 5.5 to MIS 5.4. Our data show that AMOC was enhanced during this latter transition as a consequence of a large increase of the overturning rate of the Intermediate Waters, above 2500 m. We suggest that this AMOC pattern required a reinforced Gulf Stream-North Atlantic Current system that ultimately supported ice-sheet growth by providing heat and moisture to the Northern high latitudes. From MIS 5.4 to MIS 5.1, the AMOC was broadly continuous below 2000 m and supported periods of ice-sheet growth. As a result, a glacial AMOC is triggered at the beginning of MIS 4 due to the extension of ice-sheet and the subsequent reorganization of deep-water formation. This study highlights the role of intermediate waters as a major player during climate change