Environmentalist food writer Michael Pollan recently made a provocative statement at the Poptech conference that quickly went viral on the Internet, that "A vegan in a hummer has a lighter carbon footprin than a meat eater in a Prius." 

Environmental experts and bloggers immediately  jumped on it and crunched the numbers to see if he could be right.  What they came up with to challenge his claim is fascinating and instructive, as is Pollan's reaction to theirs.  Read all about it here. 

Note:  The question is clearly academic, because one would be hard-pressed to find any vegan willing to travel in a Hummer, whereas it's safe to say that most Prius drivers indulge in flesh eating.