Salon had a very intersting article recently that took a second look at the assumption that eating local necessary reduces your carbon footprint. The author, based in San Francisco, compared the fuel used per pound of produce for bringing local and non-local items to his nearby markets. Because the Bay Area growers drove smaller trucks, the fuel used per pound was usually higher than the corresponding ratio for non-local produce, which came in high-capacity trucks from places like Arizona and Mexico. For example:
Apple distributors got almost all their apples from Washington’s Yakima Valley, about 700 miles away. (Safeway’s California stores get Granny Smith apples from Stockton during fall and winter, and from Washington the rest of the year.) While the two local apple farmers traveled one-tenth the distance, their loads averaged less than 700 pounds — and generated six times more carbon dioxide per pound of apples than the semi-trailer trucks.
The article did acknowledge (though perhaps not thoroughly enough) that this discrepancy may be unique to California, where the line between local and non-local is blurrier:
Local oranges didn’t fare much better. Part of the reason is that “conventional” oranges are local, too. Distributors shipped most of their oranges from California’s Central Valley, a mere 200 miles from San Francisco and the home of several farmers market vendors.
Conventional oranges in my supermarket here in DC are still going to be from California. Indeed, in those grocery stores that list the place of origin of each item (such as Whole Foods), it often feels like almost everything in the produce section comes from California. So instead of dealing with distances of a few hundred miles for “conventional” produce, we’re looking at 3,000.
Or perhaps even more. The author noted that his calculations for non-local produce included only the mega-truck’s distance driven between the distributor and the far-away grocery store. But presumably the produce has to travel at least some distance from the mega-farm to the distributor to get to the mega-truck, and perhaps that distance is traversed in smaller vehicles than the eventual mega-truck. The article touches on this idea, but then provides no follow-up:
For one, I’d asked the wholesalers how far their produce traveled to the terminal market — but what about the extra leg from the terminal market to the retail store? For that matter, how much carbon dioxide was emitted while consolidating 45,000 pounds of produce from various farms into one semi-trailer truck? And how about the distance traveled by the consumers themselves, whether to the grocery store or to the Farmers Market? What kind of cars did they drive?
Food researchers felt my pain. “There are so many complexities,” says Holly Hill, author of a 2008 food miles review for the National Sustainable Agriculture Information Service. “Trying to make those real exact calculations is nearly impossible.”
Which is too bad. It would be good to know those calculations. Of course, any time you’re able to grow food yourself, your mileage will be definitively low.