For the first time, researchers have developed a data set quantifying what the social cost of carbon—the measure of the economic harm from carbon dioxide emissions—will be for the globe’s nearly 200 countries, and the results are surprising. Although much previous research has focused on how rich countries benefit from the fossil fuel economy, while damages accrue primarily to the developing world, the top three counties with the most to lose from climate change are the United States, India and Saudi Arabia—three major world powers. The world’s largest CO2 emitter, China, also places in the top five countries with the highest losses.