Sea surface temperature in the Indian sector of the Southern Ocean over the Late Glacial and Holocene

• Published in: Climate of the Past
• Main Authors: Orme, Lisa Claire, Crosta, Xavier, Miettinen, Arto, Divine, Dmitry, Husum, Katrine, Isaksson, Elisabeth, Wacker, Lukas, Mohan, Rahul, Ther, Olivier, Ikehara, Minoru
• Other Authors: Norwegian Polar Institute, National University of Ireland Maynooth (Maynooth University), Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), University of Helsinki, Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology Zürich (ETH Zürich), Kochi University
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2020
• Subjects: [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; Indian; Southern Ocean; ice core
• Online Access: https://hal.archives-ouvertes.fr/hal-02913100; https://hal.archives-ouvertes.fr/hal-02913100/document; https://hal.archives-ouvertes.fr/hal-02913100/file/Orme_CP2020.pdf; https://doi.org/10.5194/cp-16-1451-2020

International audience Centennial-and millennial-scale variability of Southern Ocean temperature over the Holocene is poorly known, due to both short instrumental records and sparsely distributed high-resolution temperature reconstructions, with evidence for past temperature variations in the region coming mainly from ice core records. Here we present a high-resolution (∼ 60 year), diatom-based sea surface temperature (SST) reconstruction from the western Indian sector of the Southern Ocean that spans the interval 14.2 to 1.0 ka (cal-ibrated kiloyears before present). During the late deglacia-tion, the new SST record shows cool temperatures at 14.2-12.9 ka and gradual warming between 12.9 and 11.6 ka in phase with atmospheric temperature evolution. This supports the evolution of the Southern Ocean SST during the deglacia-tion being linked with a complex combination of processes and drivers associated with reorganisations of atmospheric and oceanic circulation patterns. Specifically, we suggest that Southern Ocean surface warming coincided, within the dating uncertainties, with the reconstructed slowdown of the Atlantic Meridional Overturning Circulation (AMOC), rising atmospheric CO 2 levels, changes in the southern westerly winds and enhanced upwelling. During the Holocene the record shows warm and stable temperatures from 11.6 to 8.7 ka followed by a slight cooling and greater variability from 8.7 to 1 ka, with a quasi-periodic variability of 200-260 years identified by spectral analysis. We suggest that the increased variability during the mid-to late Holocene reflects the establishment of centennial variability in SST connected with changes in the high-latitude atmospheric circulation and Southern Ocean convection.