To imagine the kind of future a hotter, dryer climate may bring, and the geopolitical challenges it will create, look no farther than two parts of the world that Donald Trump wants America to control: Greenland and the Panama Canal.The president-elect in recent days has insisted that both places are critical to United States national security. He’s called to reclaim control the Panama Canal from Panama and acquire Greenland from Denmark, both sovereign territories with their own governments.They have something else in common as well: Both are significantly affected by climate change in ways that present looming challenges to global...