Must read: Gut Check: Here’s the Meat of the Problem
According to a 2006 United Nations report, livestock accounts for 18 percent of worldwide greenhouse gas emissions.
. . . Two researchers at the University of Chicago estimated that switching to a vegan diet would have a bigger impact than trading in your gas guzzler for a Prius (PDF). A study out of Carnegie Mellon University found that the average American would do less for the planet by switching to a totally local diet than by going vegetarian one day a week.