According to this report, producing 2.2lbs of edible beef produces as much greenhouse gas at driving three house straight:
Most of this comes from the methane release from the cows, and this is spread out over the lifetime of the cow.
This report comes on the heals of a court decision saying that the EPA does not have to enforce environment rules on farms it has agreements with, and those farms can not be sued for violations of EPA rules:
Why are we not enforcing EPA rules on farms? I suspect it is because it would cause the price of the Big Mac to skyrocket and business interests are lobbying hard to keep the American institution of cattle "ranching" (sorry, I have trouble considering feed lots real ranching) free of having to meet EPA standards.
I love beef, be it hamburgers, steak, or even liver, but I see how fat I am and most of America is and I can't help but think that if we can enforce the EPA rules and help the environment AND as a side affect cause people to eat less red meat, it would be a boon for our nation.
I believe that if we get rid of feed lots and return to free range cattle without hormones it would raise the price of beef, reduce the amount of cattle producing methane, and help our diets.
The downside is that without legislation regulating beef imports, demanding foriegn raised beef have the same standards for emissions and the way the cattle was raised, it would just mean cheap foriegn beef would destroy the U.S. beef industry.
I also believe that our nation being dependent on any other nation for a needed resource, be it food or fuel, is a threat to national security. I don't think we should keep local food production industries safe with tariffs and subsidies, but rather by making it so that all imported food must me raised/made by the standards we have here.