Canada and the European Union are among the io largest emitters of greenhouse gas emissions, accounting for two and 14 percent respectively of global carbon dioxide emissions. Both have large environmental communities and strong environmental regulatory capacities, and both are parties to most major multilateral environmental agreements. The European Union pushed strongly for the ratification of the Kyoto protocol after the United States pulled out of the agreement in 2001, threatening the future of the regime. Canada, which had been one of the first countries to sign the Kyoto protocol, joined the EU in ratifying it in 2002.Despite these similarities, Canada and the EU in recent years have had very different experiences with climate policy implementation and have taken substantially different positions towards the establishment of postKyoto climate reduction goals. Canada committed to reducing its greenhouse gas emissions by six percent of 1990 levels by 2012. The EU-15 (that is, the 15 members of the European Community at the time the Kyoto protocol was formulated) committed to an eight-percent reduction over the same time frame.The EU-15 are well on track to meeting their Kyoto protocol target and could even surpass it. At the end of 2008, greenhouse gas emissions in the EU-15 were 6.9 percent below 1990 base year emissions. The remaining cuts that need to be made can be achieved through a combination of planned domestic mitigation measures and reliance on the Kyoto flexibility mechanisms (emissions trading, joint implementation, and the clean development mechanism).Future EU emission targets are based on the EU-27 membership. In late 2007, the EU set a target to reduce EU-27 greenhouse gas emissions by 20 percent of 1990 levels by 2020, independent of other country actions in the international climate negotiations. The EU has stated it will move to a 30-percent reduction target if other countries take comparable action. The EU-27 are also making progress on their 20-percent reduction goal. Emissions in 2008 were 11.3 percent below 1990 levels.1In contrast, Canada is far from meeting its Kyoto emissions reduction target and has set a weak goal for 2020. Canadian emissions were 24.1 percent higher at the end of 2008 than in 1990, or 31.5 percent above the Canadian Kyoto target. To put this into perspective, US emissions were 14 percent higher in 2008 than in 1990.2 Canadian emissions have been growing faster than those of any other G8 country. At the Copenhagen climate conference in December 2009, Canada set a new climate target: a 17-percent reduction in greenhouse gas emissions by 2020, relative to 2005 emission levels.3 The World Resources Institute calculated that this is equivalent to a three-percent increase in emissions over 1990 levels, or a 19-percent increase when land use, land use change, and forestry measures are included in the calculation.4The Conservative minority government that has been in power since 2006 has questioned the Kyoto protocol's fairness, Canada's ability to meet its target, and the economic impact that mitigation efforts required by Kyoto would have on the economy.5 In November 2009, in the run-up to the Copenhagen climate convention, the Canadian senate defeated a bill introduced by the opposition that called for cuts in greenhouse gas emissions by 25 percent of 1990 levels.6What explains the differences in Canadian and European approaches to climate change and are the differences really as large as these figures suggest? Clearly, at the aggregate level, the EU has outperformed Canada. Yet when the performance of Canadian provinces and EU member-states is considered, the picture is more nuanced. Both within Canada and the EU there are substantial differences among provinces/member-states in their greenhouse gas performance and support for strong climate policies. This article compares the opportunities and constraints that federalism places on Canada and the EU in terms of their climate policymaking. …