Climate of the Past Discussions www.clim-past-discuss.net 1814-9340 1814-9359 6 4 2010 10.5194/cpd-6-1337-2010 http://www.clim-past-discuss.net/6/1337/2010/ http://www.clim-past-discuss.net/6/1337/2010/cpd-6-1337-2010.html http://www.clim-past-discuss.net/6/1337/2010/cpd-6-1337-2010.pdf 1337 1350 2010-07-12 Uncertainty of the CO₂ threshold for melting a hard Snowball Earth Y. Hu yyhu@pku.edu.cn J. Yang Dept. of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing 100871, China One of the critical issues of the Snowball Earth hypothesis is how high level of CO₂ is required for triggering the deglaciation. Using Community Atmospheric Model version 3 (CAM3), we study the problem for the CO₂ threshold. Our simulations show large differences from previous results (Pierrehumbert, 2004, 2005). 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