Buy local food for its freshness. Buy it to preserve open space and support the local economy. But don't do it to save the planet.
The flawed logic of food miles: here's where we went wrong.
We always knew that there was something wrong about eating air-freighted raspberries in the dead of winter, and when the term food miles entered the enlightened lexicon it gave us a way to quantify it. Food miles taught us to measure the distance that food travels from farm to plate and to calculate the related carbon emissions based on that mileage. Fewer miles was supposed to mean less environmental impact.
If only it were that simple.
At first glance monitoring food miles seems to be a fine way to reduce carbon emissions. Now we know that it's not how far the food travels that counts, but how it's grown and how it gets to market. If you're not careful, cutting food miles can actually increase your food’s carbon footprint.
Miles are only part of food's carbon impact, and they turn out to be a pretty small part.
Studies show that 83% of the carbon emissions produced by the food system come from food production and 5% from wholesale and retail activities. On average only 4% of total emissions are generated by delivery transport from the producer to the retailer. And closer is not necessarily better. Unless your local farmer or wholesaler makes deliveries in a hybrid truck, a big rig hauling tons of produce in a single, long-distance load will produce less carbon dioxide per pound of food. Air-freighted winter raspberries, though, are never the right choice: food that flies can produce up to 15x more carbon emissions than food that's trucked in, and 100x the emissions than if it traveled by ship.
Whatever the mode of transportation, the environmental impact of food miles is dwarfed by the carbon emissions produced by food production. And once again, local doesn't always mean better. Even after accounting for the food miles, fruits and vegetables that can be grown outdoors in distant, tropical climates will nearly always be greener than local crops that have to be grown in greenhouses.
The key to eating local foods is to eat with the seasons.
When food is local and in season, the emissions created by both production and transport are limited. And of course fresh, local, seasonal foods just taste so much better.
The National Restaurant Association named local foods a 'hot trend in 2013.' Lay’s potato chips is running commercials featuring farmers who bring the simple happiness of farm life to big cities across America— including one whose ‘local farm’ covers 17,000 acres in 11 states. See how Big Food is co-opting the local food movement in Gigabiting's Buying Local: Is it style over substance?
Gigabiting: where food meets culture and technology.
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