Strong rhetorical differences between the European Union and the United States on climate matters have been evident for almost two decades. Since the mid-2000s, such differences are becoming visible in their respective climate policies as well. We propose three explanations for differences in climate policy outcomes in the EU and the US. First, the agenda-setting privileges of their policy-makers are significantly different, influencing how agenda setters shape policies and link issues, such as energy and climate policy. Second, while issue linkage has helped overcome distributional obstacles in the EU, it has led to more complexity and greater policy obstacles in the US. Finally, legislative rules, procedures, and norms have constrained the coalition-building efforts of lawmakers in the two systems in different ways, affecting negotiation processes and outcomes. Such differences in agenda-setting privileges, potential for issue linkages, and legislative procedures in the EU and the US have left them wide apart in international climate negotiations.

The European Union has played a leading role in pushing for the establishment, ratification, and meaningful implementation of the Kyoto Protocol to the United Nations Framework Convention on Climate Change , although it still has significant efforts to make to achieve its target of an 8 percent cut of greenhouse gas by 2008–2012 relative to the 1990 level. This article explores the political factors behind continued EU leadership in climate change. It argues that a few individual states (including Sweden, the Netherlands, Denmark, Germany, and the UK) played an essential role in establishing the EU's agenda in this domain. However, the decentralized governance structure of the EU has also encouraged a process of mutual reinforcement, whereby individual states, the European Commission, and the European Parliament are competing for leadership.

In 2001, the Japanese government committed to ratify the Kyoto Protocol to the United Nations Framework Convention on Climate Change against industry pressures and in spite of the US decision to withdraw from the agreement. This commitment was crucial for the survival of the protocol. Japan has subsequently introduced substantial—yet, mostly voluntary—measures. To explain the puzzle of Japan's ratification, this article builds upon the agenda-setting literature and advances the concept of embedded symbolism. During the 1990s, political leaders elevated climate change and the Kyoto Protocol to the level of a national symbol. Thus, although in 2001 successful implementation of the Kyoto target looked extremely difficult and industry opposition was strong, the symbolism of Kyoto backed by strong public support tipped the balance in favor of ratification.