Time Magazine: It can be difficult in the middle of winter — especially if you live in the frigid Northeastern U.S., as I do — to remain convinced that global warming will be such a bad thing. Beyond the fact that people prefer warmth to cold, there’s a reason the world’s population is clustered in the Tropics and subtropics: warmer climates usually mean longer and richer growing seasons. So it’s easy to imagine that on a warmer globe, the damage inflicted by more frequent and severe heat waves would be …