This paper investigates the long-run effects of climate change on conflict by examining cooling from 1400-1900 CE, a period that includes most of the Little Ice Age. We construct a geo-referenced and digitized database of conflicts in Europe, North Africa, and the Near East from 1400-1900, which we merge with historical temperature data. We first show that during this time, cooling is associated with increased conflict. Then, turning to the dynamics of cooling, we allow the effects of cooling over a fifty-year period to depend on the extent of cooling during the preceding fifty-year period. We find that the effect of cooling on conflict is significantly larger if the same location experienced cooling during the preceding period. We interpret this as evidence that the adverse effect of climate change intensifies with its duration.