Locally grown, but is that lettuce really ‘green’?

U. CHICAGO (US)— When it comes to food, local is where it’s at for those concerned about their carbon footprint. But Pamela Martin from the University of Chicago says the idea that local foods are more sustainable is really just an assumption. She and her students are crunching the numbers, determined to find out if regional agriculture really does have a green edge over conventional framing.

Martin hopes to establish baseline data on the environmental impact of local agriculture. “Is it just as or more energy efficient than conventional agriculture? If so, let’s use that knowledge when we are putting policies into place. Or is it not even as efficient? And if not, can we improve its energy efficiency?”

She points to a growing list of cities, including Chicago, adopting initiatives designed to foster more investment in local and regional agriculture, all based on the assumption that doing so will help reduce greenhouse-gas emissions. Martin, assistant professor in geophysical sciences at Chicago, says it may not be that simple.

“There are a lot of qualitative ideas about this and some intuition, but not a lot of hard numbers.”

Urban food chain
In January, Martin launched a yearlong course to get those numbers. Titled, “Feeding the City: The Urban Food Chain,” the course doubles as a research project. A portion of the course consists of a paid internship for 12 students, who will spend the summer working and collecting data at an urban or rural small farm.

“They’re responsible for communicating with the farmer during this whole time, helping them keep records, because this is all about record-keeping,” Martin explains. Her team of undergraduates from a variety of disciplines will document all farm inputs, both direct and indirect (fuel and seed consumption, for example), and output (yield).

Six other students will supplement the interns’ work. Their tasks will range from collecting data about the farms’ locations and distribution networks—right down to the size of trucks used to transport their food into the city—to evaluating the relevant research literature.

The calculus of food

“We’re trying to calculate energy efficiency from food grown in this way, and also look at the greenhouse-gas emissions. As the study progresses, we hope to use the data we collect to develop new environmental metrics, ” Martin says.

The farms participating in the project each raise a diversity of crops in hundreds of varieties. Traditional farms, by contrast, usually grow only one or two crops and varieties.

Collaborating with Martin on related agriculture projects are two Chicago colleagues, an economist and a law professor. David Weisbach, the Walter J. Blum Professor in Law, and Martin are working together to explore the practicality of a tax-credit system for greenhouse gas emissions related to agriculture.

The economics of efficiency
Work with Sabina Shaikh, instructor in economics and the social sciences collegiate division, will attempt to establish a relationship between economic factors and environmental efficiency on the farms.

“Farmers can really see their economic viability or their economic efficiency. The environmental impact is not so easy to see,” Martin

A challenge Chicago graduate student Esther Bowen encountered when she began working on her senior thesis in environmental studies. Bowen, a teaching assistant for Martin’s course, recruited the farms participating in the study and coordinates student involvement. For her senior thesis, with Martin as her adviser, she set out to determine what food the dining halls bought, and what they should buy under a sustainable food program.

“I realized, no one really knows what ‘sustainable’ means for food in such a situation,” Bowen says. So instead, she examined the carbon impact per unit weight of organic versus locally grown fruits and vegetables, framing a question often faced by environmentally minded consumers when local, organic options are limited. According to Bowen’s study, on the whole, buying local foods can potentially result in greater carbon emissions savings.

“But, it’s just one metric and there is incomplete data, and there are a lot of other metrics that need to be investigated,” Bowen adds. “If anything, it’s a call for more research.”

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