LONDON — About two years ago, I realized that the military in various countries were starting to do climate-change scenarios in-house — scenarios that started with the scientific predictions about rising temperatures, falling crop yields and other physical effects, and examined what that would do to politics and strategy.
The scenarios predicted the proliferation of failed states because governments could not feed their people; waves of climate refugees washing up against the borders of more fortunate countries; even wars between countries that shared the same rivers.
So I started interviewing everybody I could get access to — not only senior military people but scientists, diplomats and politicians. About 70 interviews, a dozen countries and 18 months later, I have reached four conclusions that I didn't suspect when I began the process: