The food we eat traverses great distances – sometimes hundreds or thousands of miles – to reach our plates. Mapping the trajectories of processed foods often means drawing zig-zags across the globe, connecting faraway fields, factories, distribution centers, and store shelves.
The concept of “food miles” was created in the 1990s to warn consumers of the connection between long-distance food transportation and mounting global carbon emissions. Recent estimates figure that, in the U.S., processed food typically travels over 1,300 miles and fresh produce over 1,500 miles before it’s consumed. Ultimately, the further food travels, the more fossil fuels are needed, which in turn results in more greenhouse gas emissions that fuel climate change.
Just ten companies – among them Nestlé, Mondolez, and Unilever – control almost all large food and beverage companies in the world. This powerful oligopoly of food suppliers has left less room for small, local farmers, and means more and more of our food is transported across the country – or the globe – before being eaten. Take Iowa, for example: in 1870, 100% of all apples consumed in the state were also produced there. By the end of the 20th century, however, only 15% of apples consumed in Iowa were grown by Iowan farmers.
The globalization of our food supply has also allowed consumers to become accustomed to foods grown only in other regions – think of coffee, which isn’t grown anywhere in the contiguous U.S. – or out-of-season foods that must be transported from warmer climates. Strawberries bought at a local farmers’ market during their summer growing season, for example, will have a lower food mileage than those shipped from California and purchased at a grocery store in December.
How Are Food Miles Calculated?
Several different methods have been devised over the years to calculate food miles. The Weighted Average Source Distance (WASD) formula developed by Annika Carlsson-Kanyama in 1997 considers the weight of the transported food and the distance it travels from the place of production to the place of sale. To analyze foods with multiple ingredients – including many processed foods, like bread, packaged desserts, snacks, etc. – The Leopold Center for Sustainable Agriculture developed the Weighted Total Source Distance (WTSD) formula, which calculates the weight and distance traveled of each individual ingredient.
The WASD and WTSD are helpful formulas, but the Weighted Average Emissions Ratio (WAER) formula – developed in 2004 by the nonprofit LifeCycles – is perhaps the most illustrative, as it takes into account the greenhouse gas emissions associated with each mode of transportation employed. It’s not the literal miles that matter, after all, so much as the climate cost associated with those miles.
The Impact of Faraway Food
Both transportation and agriculture are major culprits in human-caused climate change. In the U.S., transportation accounts for the largest share of national greenhouse gas emissions, and, according to the IPCC, agriculture accounts for one-fifth of worldwide CO2 emissions. The U.S. food system in particular stands out, consuming more energy than all of France annually.
Within this food system, transportation comprises 14% of all energy used. The size of a food’s carbon footprint also has to do with where it was produced: The Leopold Center found that conventionally sourced food costs four to seventeen times more fuel than local food and produces five to seventeen times more CO2. For processed foods, the impact is even larger. Think of a frozen lasagna: the wheat for the pasta might be grown in Kansas, the tomatoes and spinach for the sauce in California, the beef raised in Texas, and the cheese made in Wisconsin. Some of these materials might even need to be transported from the farm to another location to be processed – like the wheat to be made into sheets of lasagna noodles – before making its way to a factory for assembly, packaging, and ultimate distribution to grocery stores.
Then there’s mode of transportation: water, road, rail, or air, in order of most to least efficient. Transporting food by plane creates 50% more greenhouse gas emissions than transporting it by sea. A 2005 study found that, while air transportation accounts for only 1% of food transportation in the UK, it is responsible for 11% of the country’s emissions.
Food mileage should also factor in how food is procured by the customer. In our car-based society, where car ownership rates by household have remained above 90% for a decade, many shoppers drive to a store to purchase their groceries. In 2015, researchers found that the median distance to the nearest food store for Americans was 0.9 miles, and that 40% of the population lived further than 1 mile from a food store, frequently necessitating driving.
Debate Over Food Miles
Climate and agricultural scientists don’t all agree on the benefits or accuracy of food miles when determining the environmental impact of food products.
Many argue that this metric doesn’t represent the complete carbon footprint of food production or adequately account for its environmental impacts beyond emissions, such as pesticide use and water pollution. “Working out carbon footprints is horribly complicated,” said African agriculture expert Gareth Edwards-Jones of Bangor University in an interview with The Guardian. “It is not just where something is grown and how far it has to travel, but also how it is grown, how it is stored, how it is prepared.”
Local food is often espoused as the greener option, but this isn’t always the case. For example, heating a greenhouse in the Northeast to grow tomatoes in the winter might actually be a more carbon-intensive process than shipping the tomatoes from California. A Swedish study found that tomatoes imported to Sweden from Spain were actually less energy-intensive than those grown locally in greenhouses.
Some companies and organizations have instead begun using the Life Cycle Assessment (LCA) method to analyze the impact of their products. This method takes into account all stages in the life cycle of the product, from production to processing to packaging to transportation to disposal. The analysis goes beyond carbon emissions and considers other valuable factors like air and water pollution, use of natural resources, and impacts on human health.
How to Reduce Food Miles
The food miles framework may be a work in progress, but it remains a useful tool to help you reduce your environmental impact through smarter food choices.
To estimate the food miles associated with your favorite products, use this food miles calculator, or do your own research on where the products come from. It might be unrealistic to expunge all faraway foods from your diet – given price and convenience – but some items may be replaceable with local alternatives. Consider joining a CSA to get fresh produce from nearby farms at regular intervals, or buying from local producers at a farmers’ market. Better yet, grow your own food! The only food mileage you’ll rack up then will be the distance from your yard to your kitchen.
Eating seasonal produce will also ensure that your produce wasn’t shipped across the country to reach your plate. While you can’t always be sure if something was transported by plane, many perishables that need to be eaten quickly after harvesting – such as berries – are, so refraining from eating these products until they’re in season is sure to cut back on CO2.
Lastly, it’s worth nothing that there are many other ways beyond food miles to minimize your food-related emissions. Limiting or cutting out meat and dairy is among the most impactful of changes, as 57% of emissions from food production are attributed to animal-based food (including the production of livestock feed). Going fully vegan or vegetarian is great, but not imperative; just reducing animal products in your diet makes a difference. Lastly, instead of tossing food scraps in the trash, compost them at home to keep organic waste out of landfills.
Linnea graduated from Skidmore College in 2019 with a Bachelor's degree in English and Environmental Studies, and now lives in Brooklyn, New York. Along with her most recent position at Hunger Free America, she has interned with the Sierra Club in Washington, DC, Saratoga Living Magazine, and Philadelphia's NPR Member Station, WHYY.