James McWilliams, author of Just Food, discusses in a recent issue of Forbes magazine how the practice of buying local does not necessarily support the aim of reducing environmental impact.

McWiliams begins by citing a 2006 academic study in New Zealand that determined Londoners could reduce their environmental impact by purchasing lamb imported from New Zealand rather than lamb produced in England, because factors other than transportation often play a far larger role in environmental impact.

Mcwilliams continues by discussing how economies of scale in production can positively distribute environmental costs:

To choose a locally grown apple over an apple trucked in from across the country might seem easy. But this decision ignores economies of scale. To take an extreme example, a shipper sending a truck with 2,000 apples over 2,000 miles would consume the same amount of fuel per apple as a local farmer who takes a pickup 50 miles to sell 50 apples at his stall at the green market. The critical measure here is not food miles but apples per gallon.

We’ve argued on this website before that locavore policies constitute a new form of protectionism. This is true, but likely not a very compelling line of reasoning for locavores.

In this case, the economically efficient and environmentally efficient solutions do not have to be polarly aligned. Locavores should understand how their actions may fail to uphold the values they are rooted in, because of logistics and unintended consequences that haven’t been thoroughly considered. It’s even more important to view with a skeptical eye any legislation, government purchases, or changes in trade policy based on the reasoning that local consumption equates to environmentally friendly consumption.