What's the carbon footprint of your dinner?

First, here's a graphic that's getting a lot of attention, just published by The Environmental Working Group, a Washington lobbying organization:

Full Lifecycle Greenhouse Gas Emissions from Common Proteins and Vegetables

Here's a graphic (thanks, Len!) showing some of the same foods with their carbon footprint for 1000 calories instead of for one kilo:

Greenhouse Gas Emissions for 1000 calories of Common Proteins and Vegetables

The first graph comes from the EWG's "Meat Eater's Guide," discussing the impact of meat eating on the environment. It illustrates the carbon footprint of common foods, measured in kilograms of carbon expended to produce a kilogram of edible food. I find the idea of comparing various foods by their carbon footprint be effective, but comparing the foods by weight seems misleading. Comparing a kilogram of tomatoes to a kilogram of edible beef seems rather naive: after all, the kilo of tomatoes supplies you with around 180 calories, while a kilo of steak is 2010 calories. Comparing these to cheese is even less helpful: a kilogram of cheddar has just over 4000 calories. To me, calorie content is a better measure of nutritional value than weight, and if you look at some of the foods from this point of view, the profile is very different, as you can see in the second graphic.

Comparing beef to lentils still gets the same result: the carbon footprint of beef is over 30 times as high as the carbon used to deliver a plate of lentils to a diner. However, in between, the differences don't come out so consistent -- cheese turns out to be a much more responsible carbon-conserving choice if you look at its calorie value.

Note: calorie values are based on the information in the USDA online calorie counter.