Food-Miles Study Spotlights Why We Need Local Food Back on the Menu

It's been 15 years since Alisa Smith and J.B. MacKinnon published their book "Plenty," more accurately titled "The 100 Mile Diet-A Year of Local Eating" in Canada, and people have been arguing about the benefits of local food ever since. Do "food miles" actually matter? A new study concludes that global food miles account for nearly 20% of total food-systems emissions and that these emissions are between 3.5 and 7.5 times higher than previously estimated.

In 2020, Hannah Richie of Our World in Data concluded that eating local is "one of the most misguided pieces of advice... GHG emissions from transportation make up a very small amount of the emissions from food and what you eat is far more important than where your food traveled from." She suggested that giving up beef was far more significant.

But when researching my book, "Living the 1.5 Degree Lifestyle," I concluded that Richie, and the studies she based her article on, grossly underestimated the impact of the cold chain. For fruits and vegetables, in particular, the transportation could be as much as 50% of their full carbon footprint. I concluded, "I don't think we should ever say that food miles don't matter, because they add up too. I can't put a hard number on it, but local food still matters."

Now, the aforementioned new study from the University of Sydney in Australia puts a hard number on it—and it's big. The authors note most previous studies just measured the food miles in tkm—the transport of a metric tonne of food one kilometer—without considering all the upstream emissions. An example they give is the shipping of fertilizer from Canada by truck to Brazil, where it is used to grow soybeans that are fed to pigs that are then shipped to China.

Like Richie, the researchers acknowledge the impact of beef, with meat production being 27% of food-system emissions and fully 39% of the 7.1 gigatonnes of carbon dioxide (CO2) emissions from food production. But food-mile emissions are still a whopping 3 gigatonnes, and refrigerated transport of vegetables and dairy amount to over half of that. This is not a number that can be ignored. The authors write:

Although "food-miles" are not and should not be considered the only indication of the environmental impact of food, they are a characteristic of every food commodity... we report that global food-miles emissions are 3.5 to 7.5 times higher than previous estimates, a finding that requires reconsideration of policies governing global food trade and consumption. In particular, vegetable and fruit consumption make up more than a third of global food-miles emissions, and almost double their production-related emissions."

The authors also state "food-mile emissions are driven by the affluent world... high income countries represent only 12.5% of the world's population, but are associated with 52% and 46% of international food-miles and emissions, respectively."

Perhaps most importantly, they conclude, unlike Richie, that what we eat is important but so is where it traveled from.

"To mitigate food system environmental impact, we conclude that the strategy of dietary change to reduce animal product consumption and promote plant-bast foods must at least be coupled with switching toward more local production in high-income countries. This strategy could be supported by tapping into the considerable potential of peri-urban [zones of transition from rural to urban land uses] agriculture in nourishing large numbers of urban residents. Our findings thus contribute to public advocacy in providing a more nuanced argument for the notion of sourcing food more locally where appropriate."

The argument really isn't so nuanced. Farmland is continuing to be paved over for subdivisions, and those peri-urban zones are particularly at risk. Fuel is getting expensive, raising transport costs. Many places that our food comes from, like California, are running out of water. And eating a seasonal diet is probably almost as important as eating a local one; hothouse tomatoes may be grown up the road but their footprint from natural gas heating the greenhouses is huge.

The message of this study is pretty clear: Local food is back on the menu.