Colin Moulder-McComb might seem an unlikely climate change refugee. The middle-aged video game developer is a middle-class Midwesterner, not an impoverished resident of a small island nation threatened by sea-level rise. But the resident of Grosse Pointe Park, Mich., an affluent, inner-ring suburb of Detroit where he lives with his wife and two kids, says global warming is destroying his family’s quality of life. In 2016, heavy rains caused their basement to fill with 36 inches of water. “We thought it was a one-and-done, so we refurnished the basement,” he recalled. After all, they had been living in southeast Michigan...