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Extending the history of atmospheric CH 4 concentrations back to 650 kyr ago

European Geosciences Union  General Assembly 2005 Vienna, Austria, 24 - 29 April 2005. Extending the history of atmospheric CH 4 concentrations back to 650 kyr ago. R. Spahni 1 , J. Chappellaz 2 , G. Hausammann 1 , L. Loulergue 2 , T. F. Stocker 1 , J. Jouzel 3

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Extending the history of atmospheric CH 4 concentrations back to 650 kyr ago

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  1. European Geosciences Union  General Assembly 2005Vienna, Austria, 24 - 29 April 2005 Extending the history of atmospheric CH4 concentrations back to 650 kyr ago R. Spahni1, J. Chappellaz2, G. Hausammann1, L. Loulergue2, T. F. Stocker1, J. Jouzel3 (1) Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland (2) Laboratoire de Glaciologie et Géophysique de l’Environnement (LGGE, CNRS-UJF), Grenoble, France (3) Laboratoire des Sciences du Climat et de l‘Environnement (UMR CEA-CNRS), CE Saclay, Gif-Sur-Yvette, France (spahni@climate.unibe.ch)

  2. Outlook A. Short introduction B. Available CH4 records (Vostok, Dome C) C. New CH4 measurements for MIS 12 to 16 and first interpretations

  3. Reconstructing atmospheric CH4 • ice sample size: ~40g • melt and refreeze technique for the extraction of the air • analysis by gas chromatography • reproducibility of ~10ppbv

  4. EPICA Dome C & Vostok ice cores Delmotte et al. (2004) EPICA Community Members (2004) Petit et al. (1999)

  5. EPICA Dome C & Vostok ice cores New data!

  6. Climate shift

  7. Climate shift

  8. Measured CH4 data

  9. Missing Termination from MIS 14 to 13

  10. Last Glacial Period MIS 3 Huber et al. (submitted 2004)

  11. Millennial Scale Variations Oppo et al. (1998)McManus et al. (1999)

  12. Conclusions for MIS 16 to 12 • Consistent with the temperature proxy dD, mean CH4 levels • were lower during interglacials 15 and 13 than in the • consecutive interglacials 11, 9, 7, 5 and 1. • High correlation to Antarctic temperature on glacial- • interglacial time scales • the climatic transition from MIS 14 to 13 is saw tooth shaped • instead of showing a clear termination • rapid CH4 increases are observed  millennial scale • variations similar to the Last Glacial Period seem to be a • robust feature of our climate system Thank you for your attention

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