This guest post is an excerpt from Cooler Smarter: Practical Steps for Low-Carbon Living, written by the Union of Concerned Scientists and published by Island Press. Find out more at www.coolersmarter.org
If the verdict is still out on organic food, what about food produced locally? Can we reduce our carbon emissions by buying local food? Are “food miles”—the miles traveled by our dinner from farm to table—a good measure of global warming impact?
At first glance, it sounds as if local must be better. If the choice is between identical food identically grown nearby or far away, local food is certainly the clear winner because it entails fewer transportation emissions. But suppose the local food is produced on a farm with higher emissions; how does that compare with the savings in transportation? In northern states, for instance, is it better to buy tomatoes grown in local, heated greenhouses or those grown in open-air fields hundreds of miles away?
To answer this question, researchers at Carnegie Mellon University studied food miles and the emissions resulting from U.S. food purchases. They calculated the total transportation requirements—and transportation emissions—of food production, not just delivery of food from farm to retail but also delivery of fertilizer, equipment, and other inputs to the farm.
Their results show that transportation accounts for only 11 percent of the carbon emissions caused by food production. Of that amount, so-called upstream transportation of inputs to the farm (or to farm suppliers) accounts for some seven percent of overall food-related transportation emissions. Most notably, perhaps, final delivery—the trip from the farm to the supermarket—accounts for just 4 percent of total food emissions on average. By comparison, production of the food accounts for 83 percent of the carbon emissions, with warehousing and wholesale and retail operations making up the small remainder.
What does this mean for you? The emissions from producing food are so much greater than those from transporting it that transportation makes up only a tiny part of your carbon “foodprint.” Even if local food eliminated all the emissions from transportation, long-distance food produced on a farm with 5 percent lower emissions might actually contribute less to global warming.
Next: the important factors that determine a farm’s footprint