Weak environmental regulation has global consequences. When domestic regulation fails, the international community can target emitters with trade policy. I develop a dynamic empirical framework for evaluating trade policy as a substitute for domestic regulation, and I apply the framework to the market for palm oil, a major driver of deforestation and global CO 2 emissions. Relative to business as usual, a domestic production tax of 50% reduces CO 2 emissions by 7.4 Gt from 1988 to 2016, amountin