1. Extending the history of atmospheric CH 4 concentrations back to 650 kyr ago European Geosciences Union European Geosciences Union General Assembly 2005 Vienna, Austria, 24 - 29 April 2005 R. Spahni 1, J. Chappellaz 2, G. Hausammann 1, L. Loulergue 2, T. F. Stocker 1, J. Jouzel 3 (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. A. Short introduction B. Available CH 4 records (Vostok, Dome C) C. New CH 4 measurements for MIS 12 to 16 and first interpretations Outlook

3. Reconstructing atmospheric CH 4 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) Petit et al. (1999) EPICA Community Members (2004)

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

6. Climate shift

8. Measured CH 4 data

9. Missing Termination from MIS 14 to 13

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

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

12. Conclusions for MIS 16 to 12 Consistent with the temperature proxy  D, mean CH 4 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 Thank you for your attention rapid CH 4 increases are observed  millennial scale variations similar to the Last Glacial Period seem to be a robust feature of our climate system