At the end of January, multiple publications including Modern Farmer and Bloomberg ran eye-catching stories on the results of a research study published in Nature. Forbes declared that, “Urban Farming Has a Shockingly High Climate Cost,” a headline that was outright wrong in terms of the study’s findings. Earth.com led with a single, out-of-context data point: “Urban agriculture’s carbon footprint is 6x greater than normal farms.”
On Instagram, urban farmers and gardeners began to express anger and frustration. Some commented on media company posts; others posted their own critiques. In February, students at the University of Michigan, where the study was conducted, organized a letter to the researchers pointing out issues with the study.
The issue most cited across critiques was simple: When urban farms were separated from community gardens in the study, the higher rate of greenhouse gas emissions reported essentially disappeared.
Now, two months later, national advocates for the multi-faceted benefits of growing food and green spaces in cities are working to counter what they see as harmful narratives created by a study they say had design flaws to begin with and was then poorly communicated to the public. Of special concern is funding for the U.S. Department of Agriculture’s (USDA) fledgling Office of Urban Agriculture and Innovative Production, which Congress has been shorting since it was established. A coalition of groups have been pushing to change that in the upcoming farm bill.
“We hope the damage isn’t already done, but we fear that publicity around this paper will minimize the advocacy of urban farmers and partners over the past many years and possibly undermine the continued and necessary investment in urban agricultural communities,” reads a letter sent to the study authors by Michigan Food and Farming Systems, the Organic Farming Research Foundation, Pasa Sustainable Agriculture, and the Ohio Ecological Food and Farm Association.
“We hope the damage isn’t already done, but we fear that publicity around this paper will minimize the advocacy of urban farmers and partners over the past many years…”
Their overall critiques of the study start with the sample set of “urban farms.”
In a conversation with Civil Eats, lead author Jason Hawes, a Ph.D. student at the University of Michigan, said this his team compiled “the largest data set that we know of” on urban farming. It included 73 urban farms, community gardens, and individual garden sites in Europe and the United States. At each of those sites, the research team worked with farmers and gardeners to collect data on the infrastructure, daily supplies used, irrigation, harvest amounts, and social goods.
That data was then used to calculate the carbon emissions embodied in the production of food at each site and those emissions were compared to carbon emissions of the same foods produced at “conventional” farms. Overall, they found greenhouse gas emissions were six times higher at the urban sites—and that’s the conclusion the study led with.
But not only is 73 a tiny number compared to the data that exists on conventional production agriculture, said Omanjana Goswami, an interdisciplinary scientist at the Union of Concerned Scientists (UCS), but lumping community gardens in with urban farms set up for commercial production and then comparing that to a rural system that has been highly tuned and financed for commercial production for centuries doesn’t make sense.
“It’s almost like comparing apples to oranges,” she said. “The community garden is not set up to maximize production.”
In fact, the sample set was heavily tilted toward community and individual gardens and away from urban farms. In New York City, for example, the only U.S. city represented, seven community gardens run by AmeriCorps were included. Brooklyn Grange’s massive rooftop farms—which on a few acres produce more than 100,000 pounds of produce for markets, wholesale buyers, CSAs, and the city’s largest convention center each year—were not.
And what the study found was that when the small group of urban farms were disaggregated from the gardens, those farms were “statistically indistinguishable from conventional farms” on emissions. Aside from one high-emission outlier, the urban farms were carbon-competitive.
“They call out the fact that that tiny sample of seven urban farms that are actually production-focused, competitive with conventional agriculture, but that one line just got buried,” said Hannah Quigley, a policy specialist at the National Sustainable Agriculture Coalition (NSAC). This aspect was especially frustrating to urban farming advocates because, as the groups who sent the letter point out, one of their biggest challenges in working with policymakers in D.C. is to get them to “regard urban farming as farming.”
Hawes said he found the critiques around lumping community gardens and urban farms together “reasonable” but that he stood by the method. He hadn’t considered including backyard gardens in rural areas in the sample, he said, even though city gardens were. “We were not necessarily attempting to compare urban and rural food production,” he said. “In fact, we chose to use the word conventional specifically because it pointed to the sort of ‘conventional food supply chain,’ which is often what urban agriculture producers are attempting to intervene in.”
