Is This True?

I’ve complained about Rolling Stone’s liberal BS in the past (though I will forever subscribe for occasional music-related bits I enjoy, so ultimately it’s “shame on me”) and recently wrote about interesting articles I read in the last of the 40th Anniversary Issues. This month’s RS featured letters to the editor regarding a few of the articles, and the one that popped out at me was from a person complaining about the fact that despite featuring noted environmentalists, including now Nobel-Prize-Winning Al Gore, not one of them mentioned the fact that global meat production’s negative impacts on the environment are even worse that those produced by the sum of auto manufacturers.

I plead ignorance: is this true? I’ve seen and read a lot about global warming, especially endless railing against auto manufacturers, ever-increasingly stringent CAFÉ standards, etc. But not once have I ever seen mentioned that meat production has such a drastically negative impact on the environment. Is this true? Can someone send me a link to this so I can learn more about it? If it is true, how come the first time I’d ever heard of it was in a letter to the editor of Rolling Stone?

Note, I’m not going to turn vegetarian either way, just as I’m not going to stop driving my 400-hp sports car that happens to get 30 mpg on the freeway. For now, I just want to be informed.