We derive a global social welfare function that is consistent with the burden sharing in the Kyoto Protocol and in one proposal for a post-Kyoto treaty. The Kyoto Protocol favored the EU, while the EU post-Kyoto proposal puts more weight on the wellbeing of other OECD countries at the expense of EU residents. Ignoring income differences, the EU proposal for a post-Kyoto treaty favors developing countries. However, if income differences are taken into account, the EU proposal is not at all generous to developing countries. © 2010 Elsevier Ltd.