Does urban farming actually reduce carbon emissions?

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One of the questions I get asked most often — at conferences, after talks, from journalists — is whether urban agriculture is actually good for the climate. The intuition is appealing. Local food, shorter supply chains, no trucks crossing the country. But sustainability research has a long track record of complicating appealing intuitions, and this one is no exception.

The paper I’ve been working toward since the early days of the FEW-meter project is finally out. Working with Benjamin Goldstein, Joshua Newell, Erica Dorr, Silvio Caputo, and a large international team, we published the largest-ever life cycle assessment comparing the carbon footprints of food from urban agriculture and conventional farming — 73 sites across the US and Europe — in Nature Cities.

The headline number is striking: on average, food grown at urban farms and gardens has a carbon footprint roughly six times higher than its conventionally grown counterpart — 420 grams of CO₂ equivalent per serving at urban sites, versus about 70 grams per serving for conventional agriculture. That’s a big gap, and it deserves some unpacking before anyone draws the wrong conclusions.

The main driver is infrastructure. Urban farms and gardens tend to rely on raised beds, imported growing media, fencing, irrigation systems, and in some cases high tunnels or other structures. The materials and energy embedded in all of that add up — and when you divide those costs by the relatively modest yields of a community garden, the per-serving carbon footprint climbs fast. Conventional agriculture, producing at massive scale, amortizes infrastructure costs to nearly nothing per unit of food.

But the average obscures a lot. About a quarter of the individually managed gardens in our sample actually outperformed conventional agriculture on a carbon-per-serving basis. What made the difference? Three things stood out: long-term site use (spreading infrastructure costs over many years), circular inputs like compost and rainwater harvesting, and strategic crop selection.

That third factor is one I find especially interesting. The comparison matters enormously. When we compare urban tomatoes to tomatoes grown in a heated greenhouse elsewhere or flown in from overseas, the urban farm looks much better. When we compare to field-grown California tomatoes in July, the urban farm looks much worse. The carbon case for urban agriculture depends heavily on what you’re substituting — and the best case is growing crops that would otherwise be produced in energy-intensive ways.

So what does this mean for urban farmers, advocates, and policymakers? I don’t think it means urban agriculture is bad for the climate. It means the climate benefits don’t come automatically. They require deliberate choices: invest in durable infrastructure, adopt circular inputs, and grow strategically. Urban farming that does those things can genuinely reduce emissions — it just doesn’t happen by default.

This is not a reason to stop growing food in cities. It is a reason to be more thoughtful about how we grow it.

Hawes, J. K., Goldstein, B. P., Newell, J. P., Dorr, E., Caputo, S., Fox-Kämper, R., Grard, B., Ilieva, R. T., et al. (2024). Comparing the carbon footprints of urban and conventional agriculture. Nature Cities, 1, 1–10. https://doi.org/10.1038/s44284-023-00023-3

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