This paper uses historical fluctuations in temperature within countries to identify its
effects on aggregate economic outcomes. We find three primary results. First, higher
temperatures substantially reduce economic growth in poor countries. Second, higher
temperatures appear to reduce growth rates, not just the level of output. Third, higher
temperatures have wide-ranging effects, reducing agricultural output, industrial output,and political stability. These findings inform debates over climate’s role in economicdevelopment and suggest the possibility of substantial negative impacts of highertemperatures on poor countries.