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Climatic interpretation of the recently extended Vostok ice records |
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| Authors: | J Jouzel C Waelbroeck B Malaize M Bender J R Petit M Stievenard N I Barkov J M Barnola T King V M Kotlyakov V Lipenkov C Lorius D Raynaud C Ritz T Sowers |
| Institution: | (1) Laboratoire de Modélisation du Climat et de l'Environnement, CEA/DSM CE Saclay, 91191 Gif/Yvette, France;(2) Graduate School of Oceanography, University of Rhode Island, 02882-1197 Narraganssett, RI, USA;(3) Laboratoire de Glaciologie et Géophysique de l'Environnement, CNRS, BP96, 38402 St Martin d'Hères, France;(4) Arctic and Antarctic Research Institute, Beringa Street 38, 199226 St Petersburg, Russia;(5) Institute of Geography, Staromonetny, per 29, 109017 Moscow, Russia;(6) Geosciences Dept, 447 Deike Bfdg, Penn State University, 16802 University Park, PA, USA |
| Abstract: | A new ice core drilled at the Russian station of Vostok in Antarctica reached 2755 m depth in September 1993. At this depth, the glaciological time scale provides an age of 260 ky BP (±25). We refine this estimate using records of dust and deuterium in the ice and of  18O of O2 in the entrapped air. 18O of O2 is highly correlated with insolation over the last two climatic cycles if one assumes that the EGT chronology overestimates the increase of age with depth by 12% for ages older than 112 ky BP. This modified age-depth scale gives an age of 244 ky BP at 2755 m depth and agrees well with the age-depth scale of Walbroeck et al. (in press) derived by orbital tuning of the Vostok D record. We discuss the temperature interpretation of this latter record accounting for the influence of the origin of the ice and using information derived from deuterium-excess data. We conclude that the warmest period of stage 7 was likely as warm as today in Antarctica. A remarkable feature of the Vostok record is the high level of similarity of proxy temperature records for the last two climatic cycles (stages 6 and 7 versus stages 1–5). This similarity has no equivalent in other paleorecords. |
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