Greenhouse Gas Concentration Records Extended Back to 800,000 Years From the EPICA Dome C Ice Core

HR: 08:05h
AN: PP31E-01 [Abstracts]
TI: Greenhouse Gas Concentration Records Extended Back to 800,000 Years From the EPICA Dome C Ice Core
AU: * Chappellaz, J
EM: jerome@lgge.obs.ujf-grenoble.fr
AF: Laboratoire de Glaciologie et Geophysique de l'Environnement (CNRS - University of Grenoble), 54 rue Moliere Domaine Universitaire, Saint Martin d'Heres, 38400, France
AU: Luethi, D
EM: luethi@climate.unibe.ch
AF: Climate and Environmental Physics, Physics Institute, University of Bern Sidlerstrasse 5, Bern, CH-3012, Switzerland
AU: Loulergue, L
EM: loulergue@lgge.obs.ujf-grenoble.fr
AF: Laboratoire de Glaciologie et Geophysique de l'Environnement (CNRS - University of Grenoble), 54 rue Moliere Domaine Universitaire, Saint Martin d'Heres, 38400, France
AU: Barnola, J
EM: barnola@lgge.obs.ujf-grenoble.fr
AF: Laboratoire de Glaciologie et Geophysique de l'Environnement (CNRS - University of Grenoble), 54 rue Moliere Domaine Universitaire, Saint Martin d'Heres, 38400, France
AU: Bereiter, B
EM: burnito@climate.unibe.ch
AF: Climate and Environmental Physics, Physics Institute, University of Bern Sidlerstrasse 5, Bern, CH-3012, Switzerland
AU: Blunier, T
EM: blunier@climate.unibe.ch
AF: Climate and Environmental Physics, Physics Institute, University of Bern Sidlerstrasse 5, Bern, CH-3012, Switzerland
AU: Jouzel, J
EM: jouzel@dsm-mail.saclay.cea.fr
AF: Laboratoire des Sciences du Climat et de l'Environnement (IPSL-CEA-CNRS-University of Versailles St Quentin), CE Saclay Annexe Orme des Merisiers, Gif sur Yvette, 91191, France
AU: Lefloch, M
EM: lefloch@lgge.obs.ujf-grenoble.fr
AF: Laboratoire de Glaciologie et Geophysique de l'Environnement (CNRS - University of Grenoble), 54 rue Moliere Domaine Universitaire, Saint Martin d'Heres, 38400, France
AU: Lemieux, B
EM: lemieux@lgge.obs.ujf-grenoble.fr
AF: Laboratoire de Glaciologie et Geophysique de l'Environnement (CNRS - University of Grenoble), 54 rue Moliere Domaine Universitaire, Saint Martin d'Heres, 38400, France
AU: Masson-Delmotte, V
EM: Valerie.Masson@cea.fr
AF: Laboratoire des Sciences du Climat et de l'Environnement (IPSL-CEA-CNRS-University of Versailles St Quentin), CE Saclay Annexe Orme des Merisiers, Gif sur Yvette, 91191, France
AU: Raynaud, D
EM: domraynaud@lgge.obs.ujf-grenoble.fr
AF: Laboratoire de Glaciologie et Geophysique de l'Environnement (CNRS - University of Grenoble), 54 rue Moliere Domaine Universitaire, Saint Martin d'Heres, 38400, France
AU: Schilt, A
EM: schilt@climate.unibe.ch
AF: Climate and Environmental Physics, Physics Institute, University of Bern Sidlerstrasse 5, Bern, CH-3012, Switzerland
AU: Siegenthaler, U
EM: siegenthaler@climate.unibe.ch
AF: Climate and Environmental Physics, Physics Institute, University of Bern Sidlerstrasse 5, Bern, CH-3012, Switzerland
AU: Spahni, R
EM: spahni@climate.unibe.ch
AF: Climate and Environmental Physics, Physics Institute, University of Bern Sidlerstrasse 5, Bern, CH-3012, Switzerland
AU: Stocker, T
EM: stocker@climate.unibe.ch
AF: Climate and Environmental Physics, Physics Institute, University of Bern Sidlerstrasse 5, Bern, CH-3012, Switzerland
AB: The deep ice core recovered from Dome Concordia in the framework of EPICA, the European Project for Ice Coring in Antarctica, has extended the record of Antarctic climate history back to 800,000 years [Jouzel et al., 2007]. We present the current status of measurements of CO₂, CH₄ and N₂O on air trapped in the bubbles of the Dome C ice core. CO₂ is measured in two laboratories using different techniques (laser absorption spectroscopy or gas chromatography on samples of 8 and 40 g of ice which are mechanically crushed or milled, respectively). CH₄ and N₂O are extracted using a melt-refreeze technique and then measured by gas chromatography (in two laboratories for CH₄). The greenhouse gas concentrations have now been measured on the lowest 200 m of the Dome C core, going back to Marine Isotope Stage 20 (MIS 20) as verified by a consistent gas age/ice age difference determined at termination IX [Jouzel et al., 2007]. The atmospheric CO₂ concentration mostly lagged the Antarctic temperature with a rather strong correlation throughout the eight and a half glacial cycles, but with significantly lower CO₂ values between 650 and 750 kyr BP. Its lowest level ever measured in ice cores (172 ppmv) is observed during MIS 16 (minimum centered at 667 kyr BP according to the EDC3 chronology) redetermining the natural span of CO₂ to 172-300 ppmv. With 2245 individual measurements, the CH₄ concentration is now reconstructed over 800,000 years from a single core, with an average time resolution of 380 years. Spectral analyses of the CH₄ signal show an increasing contribution of precession during the last four climatic cycles compared with the four older ones, suggesting an increasing impact of low latitudes sources/sinks. Millennial scale features in this very detailed signal allows us to compare their occurrence with ice volume reconstructions and the isotopic composition of precipitation over the East Antarctic plateau. N₂O is still affected by glaciological artefacts involving dust content in the ice, and its exact temporal evolution remains to be deciphered. These measurements represent the basis of the so-called "EPICA Challenge" [Wolff et al., 2005]: they will put the climate and carbon cycle modelers under the challenge of fully understanding how orbital parameters and climate system configurations could have built such tight coupling between atmospheric composition and natural climate change during the late Quaternary. Jouzel et al., Science 317, 793-796, 10 August 2007 Wolff et al., EOS 86, N°38, 341-345, 20 September 2005
DE: 0330 Geochemical cycles (1030)
DE: 1610 Atmosphere (0315, 0325)
DE: 1620 Climate dynamics (0429, 3309)
DE: 3344 Paleoclimatology (0473, 4900)
DE: 4900 PALEOCEANOGRAPHY (0473, 3344)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting