In 1993, a Swedish researcher calculated that the ingredients of a typical Swedish breakfast-apple, bread, butter, cheese, coffee, cream, orange juice, sugar-travelled a distance equal to the circumference of the Earth before reaching the Scandinavian table. In 2005, a researcher in Iowa found that the milk, sugar, and strawberries that go into a carton of strawberry yogurt collectively journeyed 2,211 miles just to get to the processing plant. As the local-food movement has come of age, this concept of “food miles” has come to dominate the discussion.
The concept offers a kind of convenient shorthand for describing a food system that’s centralized, industrialized, and complex almost to the point of absurdity. And, since our food is transported all those miles in ships, trains, trucks, and planes, attention to food miles also links up with broader concerns about the emissions of carbon dioxide and other greenhouse gases from fossil fuel-based transport.
So is eating local food better? And what exactly is “local food” in the first place? How local is local?
One problem with trying to determine whether local food is greener is that there’s no universally accepted definition of local food.
There’s some evidence that a popular understanding of local food is, at least in some places, coalescing around a 100-mile limit. A 2008 Leopold Institute survey of consumers throughout the United States found that two-thirds considered local food to mean food grown within 100 miles. Still, a variety of other definitions also persist. Sometimes local means food grown within a county, within a state or province, or even, in the case of some small European nations, within the country. All of those are perfectly valid ways of thinking about local. But they don’t have all that much to do with environmental costs and benefits.
In any case food miles don’t tell the whole story. “Food miles are a good measure of how far food has travelled. But they’re not a very good measure of the food’s environmental impact.”
That impact depends on how the food was transported, not just how far. For example, trains are 10 times more efficient at moving freight, ton for ton, than trucks are. So you could eat potatoes trucked in from 100 miles away, or potatoes shipped by rail from 1,000 miles away, and the greenhouse gas emissions associated with their transport from farm to table would be roughly the same.
The environmental impact of food also depends on how it is grown. Swedish researcher Annika Carlsson-Kanyama led a study that found it was better, from a greenhouse-gas perspective, for Swedes to buy Spanish tomatoes than Swedish tomatoes, because the Spanish tomatoes were grown in open fields while the local ones were grown in fossil-fuel-heated greenhouses.
However, what if water shortages require Spanish growers to install energy-intensive irrigation systems? And what if greenhouses in northern Europe were heated with renewable energy?
Perhaps it’s inevitable that consumers gravitate to a focus on food miles-the concept represents the last step before food arrives on our tables, the part of the agricultural supply chain that’s most visible to us. And indeed, all other things being equal, it’s better to purchase something grown locally than the same thing grown far away.
But a broader, more comprehensive picture of all the trade-offs in the food system requires tracking greenhouse gas emissions through all phases of a food’s production, transport, and consumption. And life-cycle analysis (LCA), a research method that provides precisely this “cradle-to-grave” perspective, reveals that food miles represent a relatively small slice of the greenhouse-gas pie.
The other clear result that emerges from these analyses is that what you eat matters at least as much as how far it travels, and agriculture’s overwhelming “hotspots” are red meat and dairy production. In part that’s due to the inefficiency of eating higher up on the food chain-it takes more energy, and generates more emissions, to grow grain, feed it to cows, and produce meat or dairy products for human consumption, than to feed grain to humans directly.
“Broadly speaking, eating fewer meat and dairy products and consuming more plant foods in their place is probably the single most helpful behavioural shift one can make” to reduce food-related greenhouse gas emissions.
Additionally, farmers who market locally are often relatively small in scale, and can more feasibly adopt environmentally beneficial practices such as growing a diversity of crops, planting cover crops, leaving weedy field borders or planting hedgerows that provide a refuge for native biodiversity, and integrating crop and livestock production. In short, the production practices matter a lot more than where the food was actually grown. If buying local also means buying with better production practices then that’s great, that’s going to make a huge difference.
So, is local food greener? Not necessarily. But look at the question from the opposite direction: if you’re a consumer interested in greener food, the local food economy is currently a good place to find it. By the same token, a farmer who sells in the local food economy might be more likely to adopt or continue sustainable practices in order to meet this customer demand.
Yet there are limits to this common-sense approach. In many areas, the climate is such that eating local, seasonal, field-grown produce would be a pretty bleak proposition for much of the year. Large concentrations of people live in areas not suited to growing certain staple crops; it’s one thing to forego bananas, but quite another to give up wheat. And population density itself works against relocalization of the food system. Most of the land within 100 miles of large cities such as New York is itself very built up; where will the farmland to feed us all locally come from?
Local food is delicious, but the problem-and perhaps the solution-is global.
Join us next week to read about an initiative started in Canada to address food miles and associated issues.