He's not talking about 'farting' when he telling people to become a vegetarian. A 2006
United Nations report suggests "livestock are responsible for 18% of
greenhouse gas emissions, far greater than that of transportation." How much energy do you think it takes to raise a cow compared to the equivalent in nutrition by way of plants? That is what this person is trying to point out. Whether the statistics are right, whether you agree or not, please at least try to think about what a person is saying and not assume that everyone on the planet is as dumb as you are.