The idea that animal products in particular (above all other foods) contribute to global warming is fairly established by studies such as one called "Diet, Energy, and Global Warming" published by University of Chicago researchers a few years ago. It is true. When considering only conventional, factory farmed meat, the less you eat of it the better. I became a vegetarian for that very reason. The silver lining is that the flaw isn't in animal products themselves but in how we produce them.
A friend of mine, Judith McGeary, produces sustainable lamb, chicken, turkey, and eggs on her small Texas farm. The sheep graze on pasture, harvesting their own food. Judith tries to source feed for the chickens and turkeys locally when possible.
Most of all, the farm represents an enormous carbon sink. Instead of collecting manure in polluting, smelly lagoons like a factory farm, Judith lets nature take its course. Dung beetles on her land take care of all of the manure and they improve the soil at the same time.
Then she sells the meat to local customers who use little oil to transport the meat home. She uses a lot of energy for refrigeration but she offsets it with solar panels on her roof. Her new home, currently under construction, will be a green building.See also : Jill Richardson's blog La Vida Locavore, and previous posts in this blog tagged "food"