This piece in the Wall Street Journal argues:
The seeds of an agricultural revolution are taking root in cities around the world—a movement that boosters say will change the way that urbanites get their produce and solve some of the world's biggest environmental problems along the way.
There some problems with this line of reasoning. Here are just a few:
- As pointed out by Harvard professor Ed Glaeser last year, some of the biggest environmental problems comes from commuters driving into the city. Diverting potential living space to crop-growing space keeps some people out in the suburbs who would otherwise live in town. The environmental costs of their commutes is likely much higher than any environmental benefits from local food.
- More generally, there are very high opportunity costs to land in the city. In non-economic terms: land in the city is really valuable because there are many alternative uses for it. While I have no issue if a city-based farm is sufficiently profitable to out-compete all the other alternative uses for the land, it is much more difficult to argue that such activities are deserving of public praise or funding.
- As we pointed out in a piece last year, transportation accounts for a relatively small portion of the environmental impacts of food production (and the overall cost of food for that matter). The implication of this insight is that production costs (and emissions) are often lower if you produce food where it can be most efficiently grown and then ship it to where it is consumed.
- Using greenhouses to grow produce (such as tomatoes) in northern climates (e.g., New York, Chicago, Boston) is likely to produce many more carbon emissions than growing produce in the naturally warm environments like Florida and shipping north (see this review).
Here is a nice review of the existing research on the topic. The authors say:
Thus, advocacy for ‘local’ food suggests that it is generally better overall to consume local food than food produced ‘non-locally’. However, a priori reasoning would question the universality of such claims, as every location is local to someone, but all locations are non-local to most people.and
We conclude that food miles are a poor indicator of the environmental and ethical impacts of food production.