When we are told “The average meal travels 1,200 miles from the farm to your plate,” we’re being told the raw distance that food has been shipped and trucked. This is commonly referred to as “food miles,” and more food miles is commonly argued to be worse for the environment than fewer food miles. One problem with this assumption is that it doesn’t take into account any food production, as Lincoln University’s study points out to us. It may actually use less energy to produce and ship lamb from New Zealand to the UK than to produce it in the UK. It may use less energy to truck or ship tomatoes from Spain than to grow them in UK greenhouses. (I’m saying “may” here because, who knows, maybe the greenhouse in the UK uses wind power.) Differences in food production can create serious offsets of transportation pollution.

Another problem with “food miles” is illustrated by the UK Department for Environment, Food, and Rural Affairs (DEFRA) report data that 48 percent of food miles come from cars being driven to the supermarket. So my average meal’s food miles decrease significantly if I walk to the store on a regular basis. Now this doesn’t mean that the vans and trucks carrying the food don’t have environmental impact, but it does illustrate how inadequate a simple distance measurement is for expressing that impact.

What DEFRA suggests instead is considering these four indicators: Transport mode (air, sea, land), transport efficiency (how large a load, how efficient the vehicle is), differences in food production systems (see Lincoln study) and wider economic and social costs and benefits. So rather than “buying local” instead of “buying global,” we might “buy shipping” as opposed to “buying air freight,” just as one example. Our grocery labeling system is not currently set up to support these indicators, and they are certainly more complicated than “food miles.” But they are more accurate.

But the DEFRA report also confirms that transport of food has environmental impact. I think that this is what leads to the local food environmental argument, which is certainly a valid one, even if “food miles” doesn’t quite cut it. And DEFRA does have some suggestions for win-win policies that we, and companies, can follow. One pretty cool finding was that if you usually drive to get your groceries, ordering them online and having them delivered to your home is massively effective in reducing both the traffic congestion and emissions associated with that last leg of the food’s journey to your table. (There’s no delivery in Walla Walla so tell your parents.)

DEFRA’s last indicator points to the larger context of the local food debate. The environmental argument for local food, which we have just seen is not always applicable, comes from a very different political background than the protectionism argument, but they both end up at the same place. The protectionist argument for local food (Support the US economy, buy local) is against free trade and against globalization. The environmentalist argument tends to also argue against free trade (for fair trade instead). Anytime you involve free and fair trade, social justice concerns start coming in (on both sides of the equation, too, I might add) that complicate the ethics of every argument.

The problem with all of these complications is that activism doesn’t work if you have to get everybody you want to reach to read a 40-page report. Information can be paralyzing, and slogans (like “buy local”) bridge the gap between activists who are up on current research and the public, who understandably aren’t. The question is, then, should we be advocating “local food” as the best thing for the environment when we know that it isn’t in every case, and might not be the best choice from a social justice perspective?