Local Foods Could Make for Greener Grocers

There was a time not so long ago when people tended to select the ingredients for their meals either from what was available that week at local markets or from out-of-season home-canned, -smoked, or -pickled goods in the family larder. No longer. Maryland cooks can pick up New Zealand lamb or Icelandic salmon any time of the year. Montana markets offer tropical bananas year-round. Indiana families can dine on Arizona tomatoes in January, even if they don’t taste as good as the locally grown ones do in August.

These two prototype ecolabels note not only the mileage a food has traveled to market in Iowa, but also indicate the efficiency of its transport. The locally grown potatoes (above) get a moderate energy-impact rating. Pirog, et al. 2002

By contrast, these pineapples, which came from Hawaii via planes and long-distance truck, get branded with a “very-high” energy impact. Pirog, et al. 2002

This chart compares, by food, how many times farther a type of produce travels to reach Iowa consumers from conventional sources, as opposed to those from local growers. Pirog, et al. 2002

Today, most people in the United States eat an international diet. Even produce from many domestic sources travels 1,000 miles or more before reaching your local grocery.

Despite that, most of us know that fresh foods are perishable. That’s why items that travel the least and end up on the dinner table quickest tend to taste the best and harbor the fewest germs.

But there’s another reason to select locally grown foods: It generally takes considerably less fuel to ship them to groceries, restaurants, and other buyers. And less fuel translates to smaller emissions of carbon dioxide (CO2) by fossil-fuel-burning ships, trucks, and trains, observes Rich Pirog of the Leopold Center for Sustainable Agriculture at Iowa State University. As a major greenhouse gas, excess CO2 in the atmosphere can foster global warming.

Over the past few years, Pirog has been looking for a way to tell shoppers whether the green groceries they’re about to buy are part of the problem or part of, in Pirog’s words, “the load less traveled.” He’s now testing on focus groups prototype point-of-sale labels–he calls them ecolabels–that indicate how much energy it took to transport produce to a buyer. Pirog concedes that supermarkets may not warm to ecolabels, as they could discourage consumption of a wide range of much-traveled foods. However, “hopefully, they will be valuable to the farmers” in marketing their goods to wholesalers or even at roadside stands.

Moreover, ecolabels could be good for homeland security analyses, Pirog asserts. That’s because today, a large share of fresh food is collected and warehoused centrally, then distributed on big trucks. This centralization means that a single terrorism act to contaminate food or disrupt distribution could have a widespread impact. Ecolabels signaling long-distance travel would highlight which foods are most vulnerable, Pirog says.

Picturing food miles

To help consumers distinguish between local and potentially road-weary foods, the Iowa State team’s prototype ecolabels include not only a mileage reading, but also a “transport environmental impact,” or TEI, rating. The latter takes into account the way food was moved–on fuel-efficient ships or trains versus energy-hungry trucks or fuel-guzzling planes.

This chart compares, by food, how many times farther a type of produce travels to reach Iowa consumers from conventional sources, as opposed to those from local growers.
Pirog, et al. 2002

These TEI distinctions can be very important, Pirog notes. A scientist in Britain discovered that trucking a pound of fruit from France into England via the 31 mile, largely underwater Channel Tunnel takes more fuel–and releases more CO2–than importing that pound of fruit by sea from New Zealand. Similarly, Pirog has found, “a Costa Rican pineapple that is shipped to Florida and then trucked to Iowa has a slightly lower TEI rating than table grapes coming [to Iowa] from California”–even though the pineapple traveled considerably farther.

In the United States, where 90 percent of domestic fruits and vegetables travel by truck, the TEI wouldn’t be much different from a straight indication of miles that a product has traveled.

What most consumers probably don’t realize, Pirog says, is that the majority of their food makes a long haul. In a new report from his center called “Checking the Food Odometer,” he calculates the average distance that 16 popular types of produce take to Iowa restaurants and conference centers. For locally grown and distributed goods, the average was about 56 miles. For those that take a more typical route from the lowest-cost provider and through a distributor, the average was 1,500 miles.

For instance, a locally distributed, Iowa-grown apple moved just 61 miles to its buyer, but the average apple coming through the conventional distribution system came from 1,726 miles away. Locally grown garlic and spinach traveled just 31 and 36 miles, respectively, while their conventionally distributed counterparts traveled some 1,800 miles.

The Pirog group’s analysis shows that for the 16 produce items studied, those supplied by conventional sources traveled nearly 27 times as far to Iowa buyers as did their locally grown counterparts.

Building a preference for low-mileage foods

Some grocers have recognized that many people choose locally grown foods for their fresher, better taste. Pirog notes that some supermarkets even include in their weekly newspaper ads the names of local farmers from whom the stores have bought produce.

In several surveys, Pirog notes, consumers have acknowledged a willingness to pay slightly more for fresher, better tasting foods. Most consumers will also choose locally grown foods over those from distant sources–and pay a small premium for them–as long as those local foods taste at least as good, he says.

For now, says Pirog, “the jury is still out” as to whether consumers would downgrade the importance of taste and price in favor of doing what’s best for the environment. If not, ecolabels will need to play up taste more than environmental issues in the buy-local message.

However, Pirog points out, environmentally conscious consumers should keep in mind that, although “buy local” suggests energy efficiency, the motto can’t serve as dogma. The real focus should be on identifying foods that use the fewest resources to reach the dinner table. For that, scientists will have to perform sophisticated analyses of not only transportation costs, but also of resources used during food production.

By way of example, he notes that Spanish tomatoes can be delivered to Swedish consumers at a lower environmental cost than that of locally grown ones. How? The Spanish tomatoes are raised in warm, open fields, while the Dutch and Scandinavian ones have to be grown in greenhouses warmed with fossil fuels.

To date, the Iowa State team has focused on fresh produce because that’s where most transportation data are. In the future, the researchers hope to expand their food-traveling analyses to meats, canned goods, and other comestibles.

Janet Raloff

Janet Raloff is the Editor, Digital of Science News Explores, a daily online magazine for middle school students. She started at Science News in 1977 as the environment and policy writer, specializing in toxicology. To her never-ending surprise, her daughter became a toxicologist.

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