The Article begins with a brief sketch of the climate regime as it has evolved under the UNFCCC and its Kyoto Protocol. It then highlights the main features of current approaches taken by the United States and the EU toward climate policy and to the global climate regime. Next, it explores some of the factors that might account for European and American policy trajectories. This discussion turns from the internal politics of the EU and the United States, to their respective identities as international actors and leaders, to European and American attitudes towards international law, and finally to the salience of international environmental norms for EU and U.S. policies. The Article concludes with an evaluation of the likely implications of these factors for the future of the U.N. climate regime and for the respective leadership roles of the EU and the United States within the regime
