The link between climate change and war seems to be clear enough, but skeptics will be shaken by the research conducted by Solomon Hsiang and his colleagues of Columbia University connecting El Niño oscillations and internal conflict over the last six decades (“Seasons of Discontent,” August 27, 2011). Niños are movements of warm water across the equatorial Pacific that increase tropical temperatures and reduce rainfall around the tropical world. These oscillations influence food production, as well. The research shows a clear link between Niños, which take place once or twice a decade, and internal conflict in ninety-three countries affected by the oscillations. Most of these countries are quite poor, which is why they cannot adapt to changes in climate. As you suggest, people in these countries adapt to climate only by fighting each other. It is clear that rising global temperatures increase the likelihood of both internal and external conflict across the globe, including the eighty-two countries not affected by Niños. But the remaining skeptics had better look into military contingency plans regarding climate change. And the American military is the best place to start. Global as it is, it cannot leave climate change to chance.