Boston Globe
07-22-07
The localvore's dilemma
Sometimes buying local food helps in the battle against climate change.
Sometimes it doesn't. And sometimes, it's just too confusing to decide.
By Drake Bennett
AT VARIOUS POINTS in the coming months, a few hundred of Vermont's most
ethical eaters will take the "Localvore Challenge." The actual dates of the
challenge vary from town to town, but the idea is that, for a single meal, or a day,
or an entire week, participants will eat only food that was grown or raised within
100 miles of where they live.
Vermont's localvores (also known as "locavores" or "locatarians") and their
counterparts around the country are part of a burgeoning movement. In recent
years, as large companies with globe-straddling supply networks have come to
dominate organic agriculture, "local" has emerged as the new watchword of
conscientious consumption. Over the past year and a half, the interest in local
food has been fueled by best-selling memoirs and manifestos about local eating
and dietary self-sufficiency, such as Barbara Kingsolver's "Animal, Vegetable,
Miracle," Bill McKibben's "Deep Economy," and Michael Pollan's "The
Omnivore's Dilemma."
The case for local food is several-fold: It tastes better, its proponents argue, and
preserves species biodiversity. It shores up small-scale economies and
communities in the face of globalization and cultural homogenization. It even,
some of its advocates claim, protects against terrorism: a decentralized food
system could limit the impact of a virus or other bio-agent introduced into the
food supply.
One of the arguments most often heard, however, is about energy. And at a time
of rising concern about climate change, the great distances that most of our food
travels are a potent symbol of the system's profligacy and cost in greenhouse
gases. For local-food activists, "food miles" have become a favored measure of
environmental impact. Food activists in the US and especially in Western Europe
have pushed to put the term on menus and grocery-store labels.
"[T]he typical item of food on an American's plate travels some fifteen hundred
miles to get there," Michael Pollan writes in "The Omnivore's Dilemma," "and is
frequently better traveled and more worldly than its eater."
But a gathering body of evidence suggests that local food can sometimes
consume more energy -- and produce more greenhouse gases -- than food
imported from great distances. Moving food by train or ship is quite efficient,
pound for pound, and transportation can often be a relatively small part of the
total energy "footprint" of food compared with growing, packaging, or, for that
matter, cooking it. A head of lettuce grown in Vermont may have less of an
energy impact than one shipped up from Chile. But grow that Vermont lettuce
late in the season in a heated greenhouse and its energy impact leapfrogs the
imported option. So while local food may have its benefits, helping with climate
change is not always one of them.
"All things being equal, it's better if food only travels 10 miles," says Peter
Tyedmers, an ecological economist at Nova Scotia's Dalhousie University.
"Sometimes all things are equal; many times they aren't."
The new research is part of an ambitious attempt to understand how food -- and
the massive, almost impossibly complex system that produces and moves it
across the globe -- affects the environment. For several years in Europe, and
increasingly here in the US as well, food analysts have started to adopt a
methodology called Life Cycle Assessment -- a comprehensive accounting of all
of the resources that go into the food network, from fertilizer and fuel to the
concrete and steel used to build a packing plant and the electricity used to keep it
cool.
These researchers laud the public interest in food and its environmental impact,
but their work, they say, shows that "local" is not the best way to think about food
and energy, or the best basis for food-buying decisions. Some of these
researchers are trying to devise more accurate ways of telling consumers the
climate impact of their food choices. But they are discovering that the task can be
tricky. The key, they argue, is to find a way to label foods that is both accurate
and simple enough for consumers to accept.
Their work also highlights a more fundamental challenge for local-food
enthusiasts. Michael Pollan states this challenge starkly: "Local means local in
season," he says. In places like Boston, it means not only summers of fresh
berries and arugula but January diets heavy on root vegetables and canned
tomatoes. Can such a movement ever find mainstream acceptance?
The American food-supply network can do certain tasks very well, and one of
them is to efficiently ship things over very large distances. The costs in energy
can be high: air shipping is by far the most fuel-intensive, and is the fastest
growing sector of food transport. However, it still only accounts for a small
minority of the food shipments into and throughout the country.
Judged by unit of weight, ship and rail transport in particular are highly energy
efficient. Financial considerations force shippers to pack as much as they can
into their cargo containers, whether they're being carried by ship, rail, or truck,
and to ensure that they rarely make a return trip empty. And because of their
size, container ships and trains enjoy impressive economies of scale. The
marginal extra energy it takes to transport a single bunch of bananas packed in
with 60,000 tons of other cargo on a container ship is more than an order of
magnitude less than that required to move them with a couple hundred pounds of
cargo in a car or small truck
"Local food systems are often built around small-scale logistics," says Chris
Foster, a research fellow at England's Manchester Business School and coauthor of a December 2006 study on the environmental impacts of food
production and consumption commissioned for Britain's Department for
Environment, Food and Rural Affairs. "You begin to make more trips in cars.
More food is shifted around in small trucks and vans, which are relatively energyinefficient ways of moving."
The difference can be dramatic, according to Rich Pirog, a food-systems
researcher at Iowa State University's Leopold Center for Sustainable
Agriculture. A bag of potatoes shipped from Idaho to Boston by rail, he
estimates, is likely to require less energy in transit than the same bag of potatoes
driven from Maine to Boston in a farmer's truck. In recent decades, the national
food-distribution system has shifted from rail to trucking, so fuel use has risen,
but that still doesn't necessarily make local the best energy option.
A study Pirog did of Iowa's food supply in 2001 suggested that a transition to a
more localized food system, at least in Iowa's case, would cut fuel use over
today's international system. But the same study found that a multi-state regional
system would be better still. The trucks transporting food in that model would be
bigger and more efficient per unit of food than in the local model, while not
traveling as far as in a national model.
How food travels, in other words, matters as much as how far it travels, and what
happens on the farm or in the kitchen can leave a much bigger energy footprint
than what happens between them.
"Often it's those activities and behaviors at the two ends of the production system
that tend to dominate," says Peter Tyedmers. Food analysts point out that, per
pound of food, the grocery shopper's drive home from the store or farmer's
market can often use more energy than the entire rest of the supply chain.
Do you think eating "local" food makes a difference when it comes to climate
change?
Life Cycle Assessment -- in essence an exhaustive itemization of a product's
every environmental impact -- was originally developed by engineers and
chemists in the late 1960s for durable goods like cars and household appliances.
Only in recent years has it started to be applied to food. Most of the food
research has been done in Europe, where energy costs are higher than in the US
and climate change has been a less contentious issue.
A few LCA studies -- of tomatoes in Sweden, of apples and lettuce in Great
Britain -- suggest that in certain situations and certain seasons, the imported
option is more energy-efficient than the local one.
During the European winter, it takes far less energy to grow produce outdoors in
a warm climate like Spain or North Africa or New Zealand than in a heated
greenhouse in Sweden or England. The energy that goes into heating that
greenhouse, the studies found, or to storing locally grown fruit at a temperature
cold enough to keep it for any length of time beyond the end of the growing
season, can easily outweigh the energy required to ship produce from a warmer
country.
One of few comprehensive studies done in North America compared the energy
used to bring consumers British Canadian farmed salmon and Alaskan wild
salmon, according to Tyedmers, who led the work. The results have yet to be
published, but Tyedners says that he found that everything from the method of
fishing to the source of a region's electricity to the form in which the fish was
transported ended up being more important factors than shipping distance.
And for cattle, the greatest climate impact comes not from hauling cows and milk
and steaks around the country, but from cow burps. Cows are impressive
emitters of methane, a greenhouse gas that is 20 times more potent than carbon
dioxide (contrary to popular belief, most of it comes out the front of the cow, not
the rear). A cow with a bit of indigestion can contribute as much to global
warming in a day as the average SUV.
But if "food miles" are such a crude measure, what's an environmentally
concerned grocery shopper to look to? Some food activists are targeting the
ends of the food production process -- farmers both in the US and Europe are
looking at ways to heat greenhouses with renewable energy, or to avoid heating
them at all even during winter, and both the British government and Ben & Jerry's
recently announced efforts to modify cow feed to reduce methane production.
Others are working to wring inefficiencies out of the local food-distribution system
by getting farmers to consolidate their produce into larger trucks making fewer
trips.
More broadly, though, some food analysts are trying to introduce LCA thinking to
consumers. The Swedish government, as well as the British retailer Tesco, has
announced plans to affix products with "carbon labels" that announce just how
much carbon was emitted in production and distribution. Here in the US, Bon
Appetit Management Company, a corporate caterer that serves Yahoo!, MIT and
others, plans to introduce a similar measure next spring.
Rich Pirog sees this as a start. Ultimately, he envisions a series of labels: In
addition to nutrition information, a box of cereal or a bunch of green beans would
bear stickers relaying their carbon emissions along with their fair-trade
credentials. The risk in such a scheme, however, is that consumers, given too
much information, absorb none of it.
Message Board Do you think eating "local" food makes a difference when it
comes to climate change?
For their part, some localvores are suspicious of such labeling proposals. "To me
the whole idea of calculating out the carbon impact way overcomplicates
something that should be pretty simple," says Robin McDermott, co-founder of
the Mad River Valley Locavores. Even if it turned out that an imported bunch of
tomatoes were somehow more environmentally friendly than a local one, she
says, she'd still go with local. "There's the taste," she says, "and you're
supporting local farmers."
Michael Pollan hastens to point out that eating locally is only part of a larger food
ethic. The problem isn't merely, he argues, that we ship our lettuce across the
country; the problem is that people living in New England, a place naturally
unfriendly to large-scale lettuce production, feel entitled to eat lettuce in
February. Before World War II, he points out, Americans ate locally and in
season because they had no choice.
"It's a new idea," he says, "this expectation that we can have a salad all year
round."
Drake Bennett is the staff writer for Ideas. E-mail drbennett@globe.com.