To perhaps make Ezra Klein's point a bit more briefly there's no reason to frame the question of whether or not we should reduce meat consumption for environmental reasons as a question or whether or not we should all become vegetarians. Most of us who eat meat in the developed world eat a sufficient amount of meat that we could eat less meat without giving meat up entirely. And since people eat food multiple times every day, this is the kind of thing where small reductions in the meat content of the average meal would have a substantial impact over the course of a year.