“Shifting totally away from red meat and dairy toward chicken/fish/eggs or a vegetable-based diet reduces GHG [greenhouse gas] emissions equivalent to 5340 mi/yr (8590 km/yr) or 8100 mi/yr (13 000 km/yr), respectively.”
“Food Miles and the Relative Climate Impacts of Food Choices in the United States.” Christopher Weber and H. Scott Matthews. Environmental Science and Technology. Apr. 2008.