Revisiting the impact of the Drake Passage opening on ocean circulation and Eocene climate - A model study with paleo-friendly conditions

• Main Authors: Toumoulin, Agathe, Donnadieu, Yannick, Ladant, Jean-Baptiste, Dupont-Nivet, Guillaume
• Other Authors: Centre Européen de Recherche et d'Enseignement des Géosciences de l'Environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-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), Michigan Technological University (MTU), Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS)
• Format: Conference Object
• Language: English
• Published: HAL CCSD 2019
• Subjects: [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics; Antarctic; Southern Ocean; Drake Passage; Antarc*
• Online Access: https://insu.hal.science/insu-02090782

International audience The impact of the Drake Passage (DP) opening on climate is being debated for dozens of years. Indeed, being one ofthe major geographical changes occurring during the Eocene and at the beginning of a global climate cooling, it hasoften generated a lot of interest. To date, even though the overall signal remains unclear, it is considered as one ofthe main potential cause of the contemporaneous climate change. Several model studies have been aiming to assessthe importance of this gateway opening through different more or less complex models. However, according to ourknowledge on palaeoenvironments, most of them considered unrealistic boundary conditions (notably a low pCO2or a today-like geography) that might corrupt the transposition of their results to the original deep-time context. Inorder to better understand if and how climate might have been affected by this gateway opening the DP questionis here evaluated using an up2date IPCC like model, the IPSL-CM5A2, and Eocene-friendly boundary conditions(1120ppm, 40Ma land-sea distribution including an open Panama Seaway). Four simulations have been performedusing a closed Drake configuration and different DP depths 100m, 300m and 1000m. Striking changes are visible,since the earliest changes of the gateway opening, in the oceans dynamics and the Southern Ocean properties.However, the Drake throughflow remains weak, by far less intense than a mature Antarctic Circumpolar Currentand effects on temperatures remain geographically constrained. These experiments should help to understand ifthe impact of the DP was progressive or rather non linear while the passage deepened. Our results are compared toNeodymium and d13C data and discussed in the broader context of the Eocene-Oligocene climatic transition.