The global climate regime, as represented by the Kyoto Protocol, may be on a collision course with the global trade policy regime, as represented by the WTO (World Trade Organization). Environmentalists fear that international trade will undercut reductions in greenhouse gas emissions as dirty production migrates to non-participating countries, a phenomenon known as leakage. Meanwhile businesspeople fear the effects on their own competitiveness of the same phenomenon. These fears have now become prominent in the policy-making process. In early 2008, legislation to enact long-term targets for reduced emission of greenhouse gases included provisions for possible barriers against imports from countries perceived as non-participating--in both Washington, DC (where the bills have not yet passed) and in Brussels (where the EU Commission Directive has gone into effect). Such provisions could be interpreted as violations of the rules of the WTO, which poses the nightmare scenario of a WTO panel rejecting a major country's climate change legislation. In light of the hostile feelings that such a scenario would unleash, it would be a nightmare for the supporters of the WTO and free trade as much as for the supporters of the Kyoto Protocol and environmental protection. The issue is just the latest and largest instance of fears among many environmentalists that the WTO is an obstacle to their goals in general. The issue transcends institutions. For the critics, the WTO is a symbol of globalization, and their fears attach also to that larger phenomenon. The first part of this paper discusses the broader issue of whether environmental goals in general are threatened by free trade and the WTO. The second half of the paper focuses exclusively on the narrower question of trade aspects of nations' efforts to implement climate change policy and whether they are likely to come into conflict with the WTO.