There is a movement of people who really want people to eat food that is produced locally. Their argument seems to be primarily about the environmental impacts of moving food long distances. In particular, they are concerned about carbon emissions and the climate change they contribute to. The local food movement does not seem like a good way to deal with this for the following reasons.
First, charging for carbon emissions will solve the problem more comprehensively. Changes in consumer behavior can only go so far. In particular, if the local food movement manages to reduce carbon emissions in food production because it reduces fuel consumption, that will just free up the saved fuel to be used elsewhere. This is a problem that befalls a lot of these consumer-focused approaches to reducing fossil fuel consumption. Reducing demand will, in all likelihood, just cause the price of fossil fuels to fall, which will lead to others buying up and using the fuels for other purposes. So these kinds of micro reductions in carbon emissions do not reduce aggregate emissions; they just move them around.
Second, even if we ignore point one, food being local does not necessarily tell us anything about its overall carbon footprint. Activists within the movement talk often of food miles under the assumption that the farther food travels to get to you, the more emissions it contributes. This is obviously wrong. For instance, suppose John drives 1 lbs of tomatoes 1 mile to the farmer’s market. Now suppose, Sally drives 3 lbs of tomatoes 2 miles to the farmer’s market. John’s food has fewer food miles, but Sally’s food has less miles per unit of food and, all else equal, less emissions per unit of food.
Moreover, the local food calculus fails to take into consideration the different rate of emissions per mile of different transportation systems. Moving a unit of food by train is way less fuel-intensive than moving it by road vehicle for instance. So moving food long distances can easily emit less than moving food short distances if 1) it allows for bundling large amounts food all together (into a rail car for instance), and 2) if it involves transportation methods that are less fuel-intensive than those used locally. Those two considerations by themselves, combined or separately, allow that far-flung food is way less carbon-intensive than local food. It just depends.
Third, local food flies in the face of specialization and the kinds of gains it allows. Some areas of the world are just much more suited to food production. Centralizing food production into those areas should allow for less resource use (waste) than spreading it out into areas that are ill-suited for food production. There is little reason, for instance, to try farming food in the middle of New York City or Boston or other such areas. In addition to wasting very valuable land on low-value production, such a move reduces the overall density of those areas. That is, people end up more spread out in a world where urban land is being used for community gardens than if that same land is being used for housing or other structures. Being more spread out will mean longer commutes and longer commutes means more fossil fuel consumption.
At the very minimum, the local food people should be more explicit about their aims and push for “low-emission food” or something like that. Food being local is neither necessary nor sufficient for it to be low-emission. But then again, this all assumes that the local food stuff is so motivated. I suspect there is a non-trivial amount of lifestyle branding stuff going on, the same stuff that gets people watery-eyed about businesses whose owners live nearby and businesses that are small. If this kind of sentimentality is also what’s driving a large part of the local food advocacy, then those advocates may not necessarily care about the difficulties local food has actually achieving its nominal goals.