If you see one of the posters right outside Prof. Cohen’s office, you will notice that there is a diagram titled “Eat Smart, Your Food Choices Affect the Climate” that shows each food and consuming 4 oz of certain food has a carbon footprint that is equivalent to a certain number of car miles driven. For example, at the best choice, eating 4 oz of lentils is equivalent to driving about 0.1 miles, while at the worst case scenario, eating lamb would be equivalent to driving about 7 miles.

http://www.earthfirst.net.au/eat-smart-how-your-food-choices-affect-the-climate.html