When researchers rack up the carbon emitted across the world, the standard trends emerge: Europeans put less CO2 into the atmosphere than Americans, but China's rapid ascent is sending its emissions shooting past those of the United States. However, this week in the Proceedings of the National Academy of Sciences, Stanford University researchers attempt to rejigger the numbers to reflect not just where the emissions are produced, but who is responsible for them—who's buying and consuming the products that cause those emissions. After study global trade databases, Steven Davis and Ken Caldiera say that in 2004,