Buying locally, but not in winter and not if it requires driving to more stores

We've all heard that buying locally-grown produce is better for the environment because of the fuel consumed to transport goods, but that isn't always the case. If you can buy locally-grown tomatoes in the middle of winter, it's likely because they've been grown in heated greenhouses over several weeks, which is far worse in terms of carbon emissions than buying tomatoes that have been transported from another country where they were grown without artificial heating. Indeed, the environmental impact of transportation is typically a drop in the ocean compared to the many different resources that go into producing our food. These resources will include the energy consumed to make it possible to grow crops in areas and seasons that are colder or drier than where they naturally grow, but also processing of food into more complex products like chocolate bars and ready-meals. As a general rule, the more processing involved, the more energy required, and this is a far more important factor to attend to in the supermarket aisle than whether something is produced locally.

If you can buy food that is both in season and locally-produced, you can avoid the burden placed on the environment by heated greenhouses and transportation at the same time, but even here there is a catch. If shoppers end up driving to more stores in their local area in search of locally-produced items, they can do more harm than good because there are vastly more cars carrying shoppers to local stores than there are supply vehicles transporting products to these stores. Even a tiny increase in the average length of a very large number of short but inefficient shopping trips will collectively consume more fuel than the relatively small number of supply vehicles that move goods efficiently in bulk through large distribution networks.

The desire to buy locally-produced goods may also conflict with humanitarian concerns to support the economies of less developed parts of the world. On the other hand, the idea of buying locally-produced goods has long been embraced without any particular environmental motive by people who see it as a virtue to support the economy of one's own region above others, a stance that is viewed by some as patriotic and by others as selfish depending on how widely one draws one's circle of concern. In any case, we can expect this motive to filter and distort the environmental messages that reach the public.

These complications naturally lead to an awful lot of confusion and few of us have the time to research the environmental consequences of every little decision we make in daily life. Nevertheless, there are some general rules of thumb we can follow. First, pay more attention to how much energy is required to produce your food (along with everything else you buy) than where it comes from. Second, if you need something that happens to be out of season where you live, buy an alternative that is grown in a region where it is in season. Third, avoid driving greater distances to shop for locally-grown produce. Instead, if you have to drive to the store, choose the most locally-grown alternative among the alternatives available at your most local store.