New research shows that shifting to lower-meat diets would allow cities to source more—or all—of their food locally.
New research shows that shifting to lower-meat diets would allow cities to source more—or all—of their food locally.
December 2, 2020
This has been a banner year for local food. As the pandemic disrupted large-scale food processing and national and international supply chains, many consumers turned to local-food options like community supported agriculture programs, local meat processors, and urban farms. While the supply chain has since stabilized, many local food advocates are hoping that this new emphasis can help make the food system more resilient in the face of other challenges, like the climate crisis.
Now, a new study from Tufts University provides the most comprehensive answers yet to an underlying, fundamental question: With the majority of people concentrated in cities, how possible is it to localize food production in the U.S.?
“It depends—based on the type of food [produced on surrounding land], based on where you live, and based on the type of diet,” said Julie Kurtz, who spearheaded the research as a master’s student alongside lead author Christian Peters at Tufts’ Friedman School of Nutrition Science and Policy.
Using data on the populations of major metropolitan areas, estimated productivity of the surrounding farmland, and food needs across seven different diets, researchers found that many cities—especially those in the middle of the country and the Northwest—could feed their entire populations with food produced within 155 miles. On the other hand, many coastal cities would need to source food from much further distances to feed their large populations.
Kurtz, who is now a research analyst at the International Food Policy Research Institute, said that the city-by-city data, now publicly available, will allow officials and policymakers to evaluate exactly what is possible and what the barriers are in their specific regions.
And while generalizations are difficult, there was one big takeaway: In all regions, shifting to lower-meat diets increased the potential to localize food production. “That’s where our model shows the most immediate opportunity,” Kurtz said. “When you move to a 20 percent omnivorous diet . . . that’s where pretty much the entire country can go local, with the exception of part of Florida and part of California.”
Of course, local food systems face many barriers beyond the mere existence of adequate farmland, including how to finance expensive infrastructure and compete with international corporations that produce vast amounts of cheap food. And while there are many ongoing debates on the benefits of localizing, experts say this kind of research is important to having a more informed conversation about the potential.
One barrier in realizing the full potential of local food systems, said Ricardo Salvador, director of the food and environment program at the Union of Concerned Scientists (UCSUS), is that many people now have a hard time imagining a world in which strawberries and pineapple are not available in Vermont in January.
“It then creates this expectation that unless we have that globalized industrial food system, we can’t feed ourselves, that there really is no other meaningful alternative,” Salvador said. “The majority of us are so blinded by that fact that we won’t even be open-minded about how much more we could do in terms of local and regional production.” This study, he said, provides data to back up what is possible.
Cities, Farmland, and Diets Across America
Over the past two decades, the body of research on the capacity of local and regional systems to feed a given population has been growing. But researchers have primarily analyzed specific foodsheds by state or region, or looked at agricultural land carrying capacity on a broader scale.
Tufts’ Peters is a leader in the field, and the new study, published in Environmental Science and Technology in September, builds on the methodologies and data developed in his previous research.
As a result, the researchers were able to paint an in-depth, national picture of local foodshed capacity. Their model analyzes data on the population of 378 metropolitan areas, county-level production capacity of cropland and grazing land, and a simulation of the land use of different diets that estimates the land requirements of 22 types of food. It takes into account food loss and waste, but does not account for potential changes in production related to climate change.
“It’s potent because it’s comprehensive,” said Salvador, who was involved in helping fund related research done by Peters more than a decade ago.
That comprehensive nature led to more conservative estimates of local food potential compared to past studies. For example, a 2015 study found that based on the standard American diet, 90 percent of the cities in the U.S. could feed their populations with food produced within 100 miles.
But, as Kurtz explained, her team’s model imposed additional restrictions, incorporating the need for grazing land, for example, separating out annual and perennial cropland, and accounting for the food needs of local rural populations. As a result, the study found only 26 percent of the metro areas included could feed their populations within that same distance while sticking to the standard American diet, which involves eating meat and other animal products multiple times a day.
The need for grazing land to satisfy the demand for beef is one reason people in many regions would have to source food from farther away, and why diets that include less of both can reduce that distance. Even cattle that spend the last part of their lives in concentrated animal feeding operations (CAFOs) spend most of their lives out on pasture.
Columbus, Ohio, for example, has enough cropland within about 200 miles to feed its population, but the range would need to extend out about 700 miles to include enough grazing land. If everyone in the city switched to a diet that included meat and other animal products at just 20 percent of meals, there would be enough grazing land within just 20 miles.
Switching to vegetarian diets that eliminate meat but include milk and eggs would decrease the amount of land needed to localize production at a similar rate. However, switching to vegan diets did not further shrink the radius needed to grow local food.
The study also improved on past research by accounting for potential competition between metropolitan areas within the same foodsheds, something regional models have generally failed to do. “If Boston and New York are suddenly competing for the same farmland and food, then you have to decide who wins,” Kurtz explained. “The nice thing with our model is that it accounts for all of that competition.”
That phenomenon contributes to the fact that the team found local food potential is more limited in Southern California, the Northeast, and Florida, where large metropolitan areas are closer together and would be sourcing from the same farmland.
The model does not go as deep as considering which crops the land in each region can provide seasonally. It assumes cropland that is currently producing a certain amount of corn per year could be used to produce an equivalent amount of tomatoes or oats, for example. But the mapping of available land based on type could provide a framework for local planning and production decisions.
“The framework suggests which regions need to prioritize local crops due to limited land resources, and which regions may have more expansive capacity to include land-intensive crops such as grains and pulses, or local livestock systems,” the authors write.
For instance, efforts to expand perennial grain production to reap climate benefits might benefit from the regional mapping of current perennial cropland the study provides. Regions that are currently growing significant corn and soy for animal feed or ethanol would be able to see how much food for local residents that same cropland could provide if production were shifted.
Limitations and Opportunities
Of course, land is very rarely the main limitation to regional production, a fact illustrated by the study’s finding that some of the metro areas with the most available nearby land also have some of the most underutilized local foodsheds. For example, 2017 USDA data found that only five percent of all Iowa farms sold food locally. But cropland—currently used primarily to grow corn and soy for global markets—is so abundant there, that the Tufts study found several small cities in the state, including Iowa City, Ames, and Dubuque, could rely on crops within about a 10-mile radius or less.
For that reason, in a 2014 review of foodshed studies, researchers noted that the entire method of analysis can make a complex issue look unrealistically simple. “The relocalization of foodsheds is not as simple as manipulating numbers . . . or even protecting more farmland via policy and regulation. Instead, [it] requires significant policy, business, behavioral, cultural, and economic shifts, in everything from production practices and supply chains to shopping and eating habits,” the paper notes.
Kurtz said the paper could provide limited help in addressing those shifts, mentioning the influence of agribusiness in keeping farmland in globally traded commodity crops and the transformation of labor and processing that increased localization would require. “Just because we have arable land doesn’t mean that we have the infrastructure in place to process all of the food, and that’s going to be really important,” said Becca Jablonski, a food systems extension economist at Colorado State University who works on rural and regional development.
For example, as the pandemic has increased the demand for local meat, small slaughterhouses have struggled to increase their capacity, leaving farmers and ranchers with nowhere to process animals.
But since the study put clear numbers on each city’s realistic local food radius, Jablonski sees real potential for it to contribute to more accurate definitions of foodsheds, which she said can help guide more effective, equitable regional food policies.
Those policies often determine which rural farms have access to the profitable market opportunities that regional food systems provide, such as farmers’ markets and institutional buying programs.
“We have 80 percent of our population living in urban areas, and [they] tend to be setting the policies—they make decisions about what’s included in ‘local’ and what’s not,” she said. “Essentially you can think of the definition of ‘local’ as setting the rules of the game; if you’re inside the area considered local, you get to participate.”
UCSUS’s Salvador added, “There are any number of farm families and rural economies that could be strengthened and thrive if they were the source of the supply for the major metropolitan areas in this study.” And he sees those thriving food economies all over the country as potential insurance against disruptions caused by crises like COVID-19.
“One of the multiple lessons of the pandemic is that we have become so dependent on the linearized industrial food system, so that if one [part of the supply chain] is disrupted, it has huge ripple effects throughout the entire food system,” he said. “Rather than take that as a one-off, rare vulnerability, we should actually learn that we need a more resilient, much more distributed food system.”
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