Picture Source: http://www.treehugger.com/20090925-nicholas-stern.jpg
I just read this article on the Times Online. Unfortunately, factory farms are the major cause for this concern, not the farmers that raise purely grass fed animals. While grass raised cows and pigs actually put back nutrients into the land, factory type "farms" take away and leave it a toxic, deadly environment.
What is also sad is this guy, Lord Stern, is talking out of both sides of his mouth. He is not a vegetarian but believes that people should be to fight global climate change. He needs to be more focused on the pollution and destruction that a factory farm has on the environment and not group in all beef and pork farmers in the same catagory. You can check it out for yourself by clicking on the link above.