Food Miles and Climate Change

This is a topic I've been thinking a lot about lately. Lots of well-intentioned people say that sourcing food locally, or indeed, growing it yourself, is the most eco-friendly option. But this article from Environmental Science and Technology (via Freakonomics via Andrew Sullivan) explains why this may not be so:

Transportation as a whole represents only 11% of life-cycle GHG emissions, and final delivery from producer to retail contributes only 4%. Different food groups exhibit a large range in GHG-intensity; on average, red meat is around 150% more GHG-intensive than chicken or fish. Thus, we suggest that 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 reduction than buying all locally sourced food.

The authors here are referring to the US. I live in the UK (though I am American), and I don't know about the corresponding numbers. But I'm going to do some looking and find out.