Climate change is a global commons problem. The costs of emissions in any given country are mostly borne by foreigners. Absent strong measures to overcome this dynamic, pursuit of national self-interest will lead peo-ple and countries to underinvest in decarbonization, relative to what is best for the world as a whole. And we do see such underinvestment. Many countries are not on track to meet their Paris Agreement pledges, and those pledges, even if met, are not ambitious enough to meet the headline temperature stabilization goals of the agreement. This is the fairly banal pursuit of national interest in the climate domain. But we’ve also seen the emergence of a stranger phenomenon: climate nationalism, or the pursuit of global climate goals through nationalistic means. These means include discriminatory subsidies for green technology production and deployment; proposed carbon tariffs, hoarding of green technology and critical minerals, and unilateral deployment of high-leverage geoen-gineering. Each of these policy interventions could be deployed in ways that reduce net climate risk and are generally deployed by policymakers that understand themselves to be doing so. However, the nationalist ele-ments of these policies often undermine their effectiveness in mitigating climate risk and generate their own costs, both for the implementing country and the world. Nonetheless, some scholars defend these policy approaches on their merits and others insist that they are necessary to build the domestic coalitions needed to enact strong climate change miti-gation policies. This paper assesses the tradeoffs involved in climate na-tionalism and sets forth a framework for assessing climate policies that contain nationalist elements, including how the governments of countries harmed by the nationalist provision and international legal institutions like the WTO should respond.