Clim. Past Discuss., 6, 1473-1501, 2010
© Author(s) 2010. This work is distributed
under the Creative Commons Attribution 3.0 License.
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This discussion paper has been under review for the journal Climate of the Past (CP). Please refer to the corresponding final paper in CP.
Rapid changes in ice core gas records – Part 2: Understanding the rapid rise in atmospheric CO2 at the onset of the Bølling/Allerød
P. Köhler1, G. Knorr1,2, D. Buiron3, A. Lourantou3,*, and J. Chappellaz3
1Alfred Wegener Institute for Polar and Marine Research (AWI), P.O. Box 120161, 27515 Bremerhaven, Germany
2School of Earth and Ocean Sciences, Cardiff University, Cardiff, Wales, UK
3Laboratoire de Glaciologie et Géophysique de l'Environnement, (LGGE, CNRS, Université Joseph Fourier-Grenoble), 54b rue Molière, Domaine Universitaire BP 96, 38402 St. Martin d'Hères, France
*now at: Laboratoire d'Océanographie et du Climat (LOCEAN), Institut Pierre Simon Laplace, Université P. et M. Curie (UPMC), Paris, France

Abstract. During the last glacial/interglacial transition the Earth's climate underwent rapid changes around 14.6 kyr ago. Temperature proxies from ice cores revealed the onset of the Bølling/Allerød (B/A) warm period in the north and the start of the Antarctic Cold Reversal in the south. Furthermore, the B/A is accompanied by a rapid sea level rise of about 20 m during meltwater pulse (MWP) 1A, whose exact timing is matter of current debate. In situ measured CO2 in the EPICA Dome C (EDC) ice core also revealed a remarkable jump of 10±1 ppmv in 230 yr at the same time. Allowing for the age distribution of CO2 in firn we here show, that atmospheric CO2 rose by 20–35 ppmv in less than 200 yr, which is a factor of 2–3.5 larger than the CO2 signal recorded in situ in EDC. Based on the estimated airborne fraction of 0.17 of CO2 we infer that 125 Pg of carbon need to be released to the atmosphere to produce such a peak. Most of the carbon might have been activated as consequence of continental shelf flooding during MWP-1A. This impact of rapid sea level rise on atmospheric CO2 distinguishes the B/A from other Dansgaard/Oeschger events of the last 60 kyr, potentially defining the point of no return during the last deglaciation.

Citation: Köhler, P., Knorr, G., Buiron, D., Lourantou, A., and Chappellaz, J.: Rapid changes in ice core gas records – Part 2: Understanding the rapid rise in atmospheric CO2 at the onset of the Bølling/Allerød, Clim. Past Discuss., 6, 1473-1501, doi:10.5194/cpd-6-1473-2010, 2010.
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