Brittany Patterson in Scientific American:
Bacon lovers of the world, rejoice! Or at the least take solace that your beloved pork belly may be better for the environment in terms of greenhouse gas emissions than the lettuce that accompanies it on the classic BLT.
This is according to a new study by researchers at Carnegie Mellon University who found that if Americans were to switch their diets to fall in line with the Agriculture Department's 2010 dietary recommendations, it would result in a 38 percent increase in energy use, 10 percent bump in water use and a 6 percent increase in greenhouse gas emissions.
The reason for this is because on a per-calorie basis, many fruits, vegetables, dairy and seafood—the foods the USDA pushes in the guidelines over sugary processed food and fats—are relatively resource-intensive, the study finds. Lettuce, for example, produces three times more greenhouse gas emissions than bacon.
“You cannot just jump and assume that any vegetarian diet is going to have a low impact on the environment,” said Paul Fischbeck, professor of social and decision sciences and engineering and public policy and one of the authors of the study. “There are many that do, but not all. You can't treat all fruits and veggies as good for the environment.”
The researchers conducted a meta-analysis of life-cycle assessments quantifying the water, energy use and emissions for more than 100 foods. They found fruits have the largest water and energy footprint per calorie. Meat and seafood have the highest greenhouse gas emissions per calorie.