Holocene long- and short-term climate changes off Adélie Land, East Antarctica

• Published in: Geochemistry, Geophysics, Geosystems
• Main Authors: Crosta, X., Debret, Maxime, Denis, D., Courty, M. A., Ther, O.
• Other Authors: Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-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), Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Histoire naturelle de l'Homme préhistorique (HNHP), Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2007
• Subjects: thermohaline circulation; Antarctica; sea ice; Holocene; insolation; [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology; Antarc*; East Antarctica; Sea ice; Southern Ocean
• Online Access: https://insu.hal.science/insu-00375925; https://insu.hal.science/insu-00375925/document; https://insu.hal.science/insu-00375925/file/2007GC001718.pdf; https://doi.org/10.1029/2007GC001718

International audience Diatom data from a marine sediment core give insight on Holocene changes in sea-surface conditions and climate at high southern latitudes off Adélie Land, East Antarctica. The early to mid-Holocene was warmer than the late Holocene with a transition at ∼4000 calendar years B. P. Sea ice was less present and spring-summer growing season was greater during the warm period relative to the cold one, thus limiting sea ice diatom production and favoring more open ocean diatom to develop. The long-term Holocene climatic evolution in East Antarctica is explained by a combination of a delayed response to local seasonal insolation changes coupled to the long memory of the Southern Ocean. Abrupt variations of the diatom relative abundances, indicating rapid climate changes, are superimposed to the Holocene long-term trends. Spectral analyses calculate robust frequencies at ∼1600 a (where “a” is years), ∼1250 a, ∼1050 a, ∼570 a, ∼310 a, ∼230 a, ∼150–125 a, ∼110 a, ∼90 a, and ∼66 a. Such periods are very close to solar activity cyclicities, except for the periods at ∼310 a and ∼1250 a, which are close to internal climate variability cyclicities. Wavelet analyses estimate the same periods but indicate nonstationary cyclicities. Rapid climate changes at high southern latitudes may therefore be explained by a combination of external (solar) and internal (thermohaline circulation) forcings.