spread of fruits and vegetables peppers kiwi salad healthy living USDA/ARS photo by Peggy Greb

Urban ag provides only small environmental benefits

New analysis of urban ag in northeastern U.S. finds regional "green" benefits consumers expect could be meager, at best.

"Buy local" sounds like a great environmental slogan epitomized for city dwellers by urban agriculture. However, when it comes to growing fruits and vegetables in vacant lots and on rooftops in cities, is the practice really better for the planet than conventional farming?

A new analysis of urban agriculture in the northeastern U.S., reported in the American Chemical Society's (ACS) journal Environmental Science & Technology, has found that the regional "green" benefits consumers expect could be meager, at best.

On the face of it, urban agriculture seems to offer clear environmental benefits, ACS said. The conventional system requires trucks to crisscross the country delivering food but releasing greenhouse gases. Rural farms can also require clearing huge swaths of forest land for crops. Some analyses have suggested that bringing agriculture into urban cities has lowered food-related greenhouse gas emissions.

However, the data used in those reports did not apply to the cold northeastern U.S. climate, where urban agriculture is starting to take root. Therefore, Benjamin P. Goldstein, Morten Birkved and colleagues from the Technical University of Denmark revisited the issue and included data from city farms in the region.

Crunching the data with the help of computer models, the researchers determined that, under optimal conditions, urban agriculture in Boston, Mass., would reduce food-related carbon emissions by only 1.1-2.9% per year and would increase land impacts by less than 1% per year.

In addition, the analysis showed that consumers in the Northeast who are really determined to lower their food-related carbon footprint should minimize purchases of meat and dairy products. That's because most urban agriculture currently operating in the northeastern U.S. doesn't include cows, other livestock and dairy production, and those account for 40-50% or more of agricultural greenhouse gas emissions and land use.

However, growing fruits and vegetables in high-density areas could have other benefits. For example, the practice could provide city residents with easier access to fresh produce.

The paper's abstract is available at http://pubs.acs.org/doi/abs/10.1021/acs.est.7b01011.

ACS is a not-for-profit organization chartered by Congress. ACS is the world's largest scientific society and a global leader in providing access to chemistry-related research through its multiple databases, peer-reviewed journals and scientific conferences. ACS does not conduct research but publishes and publicizes peer-reviewed scientific studies. Its main offices are in Washington, D.C., and Columbus, Ohio.

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