Food Miles

by Jeremy Cohen Hoffing May 2, 2010

“How far your food travels has serious consequences for your health and the climate”

The term “food miles” refers to the distance your food travels, from where it was grown to where it is bought and consumed. Many foods you eat today travel long distances by planes, trains, ships and trucks, which all use large amounts of energy and pollute the environment. The typical American prepared meal contains, on average, ingredients from at least five countries outside the United States.

The Leopold Center for Sustainable Agriculture, a leading researcher of food miles in the U.S., has conducted several studies calculating the distance certain foods traveled to reach the Chicago Terminal Market. Grapes, lettuce, spinach, broccoli, cauliflower and green peas traveled over 2,000 miles to reach the Chicago market.

Another study conducted in Ontario investigated the food miles associated with 58 commonly eaten, imported foods. The study found that each food item traveled an average of 2,811 miles, producing 51,709 tons of greenhouse gas emissions annually. None of these calculations include the distance that consumers drive to shop for food, which may have an even greater impact then the environmental cost of importing the food itself.

The modes of transportation also have a significant effect on the amount of pollution being generated. Importing food by airplane contributes to much greater emissions of greenhouse gases than imports by ship. In 2005, the import of fruits, nuts, and vegetables into California by airplane released more than 70,000 tons of C02, which is equivalent to more than 12,000 cars on the road. Air transport is the fastest growing mode of food distribution, and results in 11% of the UK’s C02 emissions.

How Are Food Miles Calculated?

Calculating food miles depends on how many ingredients the food has and what mode of transport is used to carry the item. The Weighted Total Source Distance (WTSD) formula, developed by the Leopold Center for Sustainable Agriculture, accounts for multiple-ingredient foods by calculating the weight and distance traveled for each ingredient. The formula they use is as follows:

WTSD = Σ (W * D * T * R) Ingredient

Where:

W = Weight of each ingredient (per container)

D = Shipping distance between ingredient origin and destination

T = Percent of total amount shipped from each origin per ingredient

R = Ratio of shipping weight to processed weight.

For a more detailed report on food miles formulas and calculations, you can visit Leopold Center’s publication, Calculating food miles for a multiple ingredient food product.

What You Can Do To Help

By purchasing food that is grown locally, you can reduce fuel consumption and greenhouse gas emissions associated with importing and transporting food. A large portion of fuel consumption and pollution is also due to the distance that consumers drive to food markets, so try walking or bicycling to the market instead. Not only will you reduce pollution, but the exercise will improve your health too!

Sources

http://www.farmlandinfo.org/documents/37291/foodmiles.pdf

http://attra.ncat.org/attra-pub/foodmiles.html

http://www.forbes.com/2007/11/11/economics-food-local-forbeslife-food07-cx_th_1113local.html