A new study shows that produce from urban agriculture has six times the carbon footprint of conventional farms when emissions are linked to food alone—but the calculation changes when the social benefits of urban growing are factored into a more holistic assessment.
“Although there remains lots of work to do in better understanding how to holistically assess urban agriculture, the project represents a useful first attempt at defining best practices that support urban agriculture that’s good for the climate in addition to being good for cities,” the study’s co-lead author, Jason Hawes, a doctoral student at University of Michigan’s School for Environment and Sustainability, told The Energy Mix.
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Recently published in the journal Nature Cities, the article by Hawes and colleagues compares the carbon footprint of conventionally grown food and vegetables against produce from 73 urban farms and gardens across five big cities in the United States and Europe. Unlike previous studies, which mainly focused on high-tech options likevertical indoor farms, this study emphasizes “open-air, soil-based” growing options that “comprise the bulk of food-growing spaces in cities.”
It finds that the carbon footprint of foods grown from urban agriculture (UA) is six times greater per serving than from conventional farming, with a few exceptions. Urban produce is carbon-competitive only against crops like tomatoes, which are conventionally grown in carbon-intensive greenhouses, or crops like asparagus that are usually air-freighted.
“Competitiveness depends on growing practices, both in urban and conventional settings,” the researchers explain, suggesting that urban growers could boost their carbon competitiveness by selecting crops that conventionally have a big footprint. They also find that urban farms tend to be the most climate friendly, outperforming individual growing plots and community gardens, in many cases.
The best ways for urban farmers and gardeners to boost their carbon-competitiveness is to extend infrastructure lifetimes and use urban waste as inputs, the researchers say.
But they note another factor that helps balance out UA’s high carbon footprint—one that does