The climate change debate in the United States has now moved beyond arguments about whether climate change is real and man-made to focus on what the country should do about the threat. This Essay takes on and debunks the "climate change winner" argument. That argument asserts that the United States is likely to fare well in a warmer world, at least compared to most other states, and therefore should invest less, rather than more, in mitigation efforts. We explain that existing estimates of the impact of climate change on the United. States systematically understate the likely economic impact of climate change, and we provide rough estimates of what a more complete accounting would reveal. Existing estimates fail to account for a variety of the costs that climate change will impose, and ignore the ways in which climate change impacts abroad are likely to spill over into the United States. By looking more carefully at these omitted costs, this Essay shows that the United States, acting in its own self-interest, should try to combat climate change. A more complete accounting of the costs reveals that the United States would be better off paying the full cost of climate change mitigation (if doing so were possible) rather than allowing the world to continue in a "business as usual "fashion. This conclusion is even stronger if Europe and perhaps the rest of the Organisation for Economic Co-operation and Development (OECD) are assumed to shoulder some of the costs. The point is not that the United States or the OECD should actually bear these costs alone, or even that it would. be possible to do so, but rather that there is a strong case for action by the United States even if some countries refuse to cooperate. This Essay shows that the United States has reason to take prompt and aggressive action to address climate change, not out of benevolence or guilt, but out of self-interest.