Enhanced Atlantic Meridional Overturning Circulation supports the Last Glacial Inception |
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| Authors: | Abel Guihou Sylvain Pichat Aline Govin Silvia Nave Elisabeth Michel Jean-Claude Duplessy Philippe Telouk Laurent Labeyrie |
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| Institution: | 1. Laboratoire des Sciences du Climat et de l’Environnement/IPSL, CEA/CNRS/UVSQ, 91198 Gif sur Yvette, France;2. Laboratoire de Géologie de Lyon, Ecole Normale Supérieure de Lyon et Université Claude Bernard, CNRS, 46 allée d’Italie, Lyon 69007, France;3. Laboratório Nacional de Energia e Geologia, Unidade de Geologia Marinha, Lisboa, Portugal;1. Department of Earth Sciences, University of Oxford, Oxford, UK;2. School of Environmental Sciences, University of East Anglia, Norwich, UK;3. Department of Earth Sciences, University of Cambridge, Cambridge, UK;4. College of Life and Environmental Sciences, University of Exeter, Exeter, UK;5. Alfred-Wegener-Institut für Polar- und Meeresforschung, Bremerhaven, Germany;1. Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ, USA;2. Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY, USA;3. Department of Earth Sciences, Durham University, Durham, UK;4. Lawrence Livermore National Laboratory, Livermore, CA, USA;5. Department of Ocean Sciences, University of California, Santa Cruz, CA, USA;1. Research School of Earth Sciences, The Australian National University, Canberra, ACT 0200, Australia;2. The Godwin Laboratory for Palaeoclimate Research, Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK;3. State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi''an 710075, China;4. Department of Earth Sciences, SUNY Oswego, Oswego, NY 13126, USA;5. Ocean and Earth Science, University of Southampton, National Oceanography Centre, Southampton SO14 3ZH, UK;1. School of Environmental and Life Sciences, The University of Newcastle, Callaghan 2308, NSW, Australia;2. School of Geography, University of Melbourne, Victoria 3010, Australia;3. EDYTEM, UMR CNRS 5204, Université de Savoie-Mont Blanc, 73376 Le Bourget Du Lac-Cedex, France;4. School of Earth Sciences, The University of Melbourne, Parkville 3010, Australia;1. Godwin Laboratory for Palaeoclimate Research, Department of Earth Sciences, University of Cambridge, Cambridge, CB2 3EQ, United Kingdom;2. Research School of Earth Sciences The Australian National University, Canberra, Australia |
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| Abstract: | 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 (231Pa/230Th) 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. |
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