Does buying local reduce fuel consumption? Redux

In November I wrote this post about how long distance shopping may use less fossil fuel than buying locally.  I created scenarios on the back of the proverbial envelope but I felt they were probably in the ballpark.

If you don't want to trust my half-assed calculation it turns out someone else with far more cred has done the math. They reached a similar result. A chap from Carnegie Mellon wrote a paper on the topic in the Journal of Environmental Science & Technology. No, I'm not a subscriber. He was interviewed in Celia Barbour's recent Oprah.com article about online shopping (which mentions Zingerman.com having "the perfect Reuben"). Here's an excerpt:

I couldn't reconcile my growing habit with my purported support for sustainable eating. 

Then I talked to Christopher Weber, research assistant professor of civil and environmental engineering at Carnegie Mellon University, who recently co-wrote a study on the carbon footprint of e-tailing and found that it's surprisingly modest -- if you buy direct from the producer.

"The biggest reason you see greenhouse-gas savings is that you don't drive to and from the store," he says. Indeed, "customer transport" accounts for 65 percent of the energy spent on traditional shopping. "Then the store itself needs to be lit and heated," he said. Add to that distribution and warehousing, and the UPS guy starts to look more and more like Al Gore.

Here's a link to Chris's entire paper. If you want to lower your food carbon footprint he gives this advice:

...dietary shift can be a more effective means of lowering an average household’s food-related climate footprint than “buying local.” Shifting less than one day per week’s worth of calories from red meat and dairy products to chicken, fish, eggs, or a vegetable-based diet achieves more GHG [Green House Gas] reduction than buying all locally sourced food.

Last but not least, the caveat I gave in my last post still stands. There are many good reasons to buy local foods—especially vegetables in season. For one, they usually taste better.