Have you heard this about global warming?

I thought this was super interesting, and it was something I've never heard in such defnite terms.  I was watching Bill Mayer on HBO the other night (I love him, such a quick witted, straight forward host...we don't always agree but he cracks me up), and he had on the woman who founded PETA.  She was speaking about the "other inconvenient" truth affecting our global environmental issue, that being that the single worst contributor to the global warming issue is the production of meat for eating.  Bigger than all the SUV's, all the factories building cars, EVERYTHING.  Apparently the physical raising of cattle does it (which I had heard, the cow "gas" and "beltching" is bad), but also the manure, and the pure inefficiency of raising so many crops to feed the animals (ie 20 lbs of corn to make 1 lb of cow).  Anyway, I thought the whole thing fascinating, because it is something that is definitely not being highlighted about the global warming issue, everyone would rather focus on the SUV's.  My big question is can I drive an Escalade if I give up meat??  (just kidding of course)  :-).  Such a bummer to love big cars AND steak.  Signed, ME {lv}