There are lots of reasons somebody might want to buy local food — freshness, distinct flavour, or even a desire to keep their dollars in their own community.

"But if you're doing it to save the planet," University of Toronto professor Pierre Desrochers says, "you're being misguided."

People shop for vegetables at the farmers' market in Berkeley, Calif., in September 2008. Locally grown produce has become increasingly popular, but the environmental benefits of the practice shouldn't be overstated, a University of Toronto professor says. (Eric Risberg/Associated Press)

A geography lecturer at the school's Mississauga campus, Desrochers recently authored a policy paper that calls into question the environmental benefit of buying locally grown food.

As globalization and environmental issues grow in prominence, a "buy local" food movement has arisen that maintains locally produced food is not only fresher and better tasting, but also better for the environment, Desrochers says.

The concept of "food miles" — the distance food has travelled from production to consumption — has been adopted as the best way of gauging a food's environmental impact.

Food miles a flawed concept, academic says

The problem, Desrochers says, is that food miles are based on a faulty premise. Namely, that transportation is the major contributor to a food's greenhouse gas output.

"People who've never been involved in agricultural production tend to minimize the requirements," he says. Only about 10 per cent of the energy consumed in food production is related to transportation. "So to argue that the closer you are to your food, the better, is a real over-simplification."

"Food miles are, at best, a marketing fad," Desrochers says in his report.

He uses the example of strawberries. Highly efficient farms in California produce roughly 17 times as many strawberries as a typical Ontario producer using the same amount of land and resources.

"When you're that efficient you can invest in better handling and storage," he says. "The environmental impact of transportation isn't very significant."

Moving that food to consumers via highly efficient rail, ocean freight or even comparatively costly air is a better move, environmentally, than trying to re-create the ideal growing conditions for the fruit in Canada, he says.

His paper is full of similar examples. European studies found that British farmers emit 2,394 kilograms of carbon dioxide for every tonne of tomatoes they produce. But Spanish farmers produce only 630 kilograms of carbon dioxide for the same amount.

'Food miles are, at best, a marketing fad.'—U of T Prof. Pierre Desrochers

Kenyan rose producers emit 6,000 kilograms of CO2 for every 12,000 cut flowers they sell in Europe, whereas their Dutch competitors generate 35,000 kilograms to accomplish the same task.

"Protectionist European farmers have been hiding behind the buy local movement for a while, but Kenya is just a lot better place to grow green beans [and other crops] than Western Europe," he says.

Desrochers is not against the idea of buying local for certain items. "Just be aware of the concept of seasons and geography."

"A 100-mile diet might be quite economical and varied in Vancouver," he says. "But it's quite a different story in Edmonton, for example."

The real enemies of environmentally conscious food consumers, he says, are food subsidies that encourage agricultural production in certain areas for the wrong reasons.

An Environmental Assessment Institute report put the total value of environmental subsidies at $376 billion worldwide in 2006.

Barriers like that, Desrochers's paper says, "end up being harmful to both the environment and the economy."