Do you know the real price of a piece of beef? Here is a nice, round number to chew on: The environmental cost of beef is ten times that of dairy, eggs or poultry. This means that if you chose to eat a steak over an omelet, (assuming they have equal amounts of protein) the ecological footprint of your meal will go from a size 5 to a size 50.
Drs. Ron Milo, Gidon Eshel, research students Alon Shepon and Tamar Makov realized that even though we might try to make the right choices in our diets, we’re likely to base them on the pronouncements of experts. The problem is that neither we nor they have a wealth of real, useful figures for comparison. So the team created a framework based on the American agricultural system and the basic American diet, and set about adding up the environmental costs for the most widely consumed animal-based proteins.
Adding up, of course, sounds like simple math. Creating aggregate numbers from the agricultural and environmental data and coming up with figures that would actually reflect reality was not. (Read the scientific paper in PNAS for the math.) And then the researchers managed to convert the inputs – land use, greenhouse gas release, irrigation and nitrogen in fertilizer – into units of output. Amount of nitrogen released into the environment per calorie of chicken, for example.
Here are some additional figures: Beef cattle require, on average, 28 times more land to provide them with food, 11 times more irrigation water, release 5 times more greenhouse gases and use 5 times as much nitrogen, in the form of fertilizer, as do eggs or poultry. While those numbers may vary a bit between grazed cattle or feed-lot cattle (the study addressed different forms of feed), the main problem is that cattle are just not efficient at converting the various inputs into edible protein.
Pork by the way, as much as it hurts a Jewish person to say this, is much more efficient – close to the environmental cost of poultry, eggs and dairy, which were all more or less tied for third place. The surprisingly high cost of dairy, says Milo, is again tied to cows’ inefficiency in producing protein, which, in turn necessitates the use of large quantities of resources, particularly water, for producing milk.
Now that these researchers have led the way, we might hope to see more comparisons – grain- and plant-based foods, for example, or Asian versus Western diets. More importantly, these numbers will hopefully help stir the debate on how we can make the transition to more sustainable agriculture for the future.