Your Food Footprint

There are lots of reasons to eat locally produced food but in my mind the most important one is the taste. Another important factor is the potential for locally produced food to have less of an environmental impact than food that has been shipped across the country or over the ocean. Unfortunately, it's not always easy to tell how much carbon has been released by the production of the food we eat. From the fertilizers (which are often petroleum based) to tractors and combines, to the trucks and trains and ships that transport the food, a lot of carbon based fuel is burned to get that loaf of bread or fresh salad on your table.

One of the worst offenders is beef, especially grain-fed beef. Two researchers from CMU's Engineering school's Public Policy department published research this spring that suggested that changing only one day per week's meat and dairy-based calories to chicken, fish, or vegetables would have about the same impact on greenhouse gases as shifting to an entirely locally produced diet. That's how bad beef is for the environment. Here is an excerpt from an article about their research:

Weber and colleague Scott Matthews, also of Carnegie Mellon, conducted a life-cycle assessment of greenhouse gases emitted during all stages of growing and transporting food consumed in the U.S. They found that transportation creates only 11% of the 8.1 metric tons (t) of greenhouse gases (in CO₂ equivalents) that an average U.S. household generates annually as a result of food consumption. The agricultural and industrial practices that go into growing and harvesting food are responsible for most (83%) of its greenhouse gas emissions.

For perspective, food accounts for 13% of every U.S. household's 60 t share of total U.S. emissions; this includes industrial and other emissions outside the home. By comparison, driving a car that gets 25 miles per gallon of gasoline for 12,000 miles per year (the U.S. average) produces about 4.4 t of CO₂. Switching to a totally local diet is equivalent to driving about 1000 miles less per year, Weber says.

Driving less and using more fuel efficient vehicles are obviously important parts of dealing with climate change, but eating less beef is more important by several orders of magnitude. A nice side benefit is the healthier heart you end up with if you replace beef with more vegetables and whole grains in your diet.

From a public policy perspective, I think that a carbon tax is probably the best way to encourage more intelligent choices by the public. Eating beef has a large cost to the environment associated with it that is largely hidden to the public. A carbon tax would capture the cost to the environment from growing the grain (fertilizers, transportation, etc.) that feeds the cattle as well as the environment costs of transporting the beef. Grass-fed beef would become less expensive relative to grain-fed beef.

When choosing what to eat, the items that do more damage to the environment ought to cost more. Often the relative price difference of our food reflects the power of different lobbies (the corn lobby is why high fructose corn syrup is so cheap, and therefore why it is in so much of our food) as much as anything else. If the price of food included the cost to the environment, then consumers could make more informed choices.