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Is Local Food Better? Yes, But There's More
http://www.worldwatch.org/node/6064?emc=el&m=227941&l=4&v=e4096cd8f2

by Sarah DeWeerdt
Published on Monday, April 20, 2009 by World Watch Magazine

In 1993, a Swedish researcher calculated that the ingredients of a typical
Swedish breakfast-apple, bread, butter, cheese, coffee, cream, orange
juice, sugar-traveled a distance equal to the circumference of the Earth
before reaching the Scandinavian table. In 2005, a researcher in Iowa found
that the milk, sugar, and strawberries that go into a carton of strawberry
yogurt collectively journeyed 2,211 miles (3,558 kilometers) just to get to
the processing plant. As the local-food movement has come of age, this
concept of "food miles" (or "-kilometers")-roughly, the distance food
travels from farm to plate-has come to dominate the discussion,
particularly in the United States, the United Kingdom, and parts of Western
Europe.

The concept offers a kind of convenient shorthand for describing a food
system that's centralized, industrialized, and complex almost to the point
of absurdity. And, since our food is transported all those miles in ships,
trains, trucks, and planes, attention to food miles also links up with
broader concerns about the emissions of carbon dioxide and other greenhouse
gases from fossil fuel-based transport.

In the United States, the most frequently cited statistic is that food
travels 1,500 miles on average from farm to consumer. That figure comes
from work led by Rich Pirog, the associate director of the Leopold Center
for Sustainable Agriculture at Iowa State University (he is also behind the
strawberry-yogurt calculations referenced above). In 2001, in some of the
country's first food-miles research, Pirog and a group of researchers
analyzed the transport of 28 fruits and vegetables to Iowa markets via
local, regional, and conventional food distribution systems. The team
calculated that produce in the conventional system-a national network using
semitrailer trucks to haul food to large grocery stores-traveled an average
of 1,518 miles (about 2,400 kilometers). By contrast, locally sourced food
traveled an average of just 44.6 miles (72 kilometers) to Iowa markets.

In light of such contrasts, the admonition to "eat local" just seems like
common sense. And indeed, at the most basic level, fewer transport miles do
mean fewer emissions. Pirog's team found that the conventional food
distribution system used 4 to 17 times more fuel and emitted 5 to 17 times
more CO2 than the local and regional (the latter of which roughly meant
Iowa-wide) systems. Similarly, a Canadian study estimated that replacing
imported food with equivalent items locally grown in the Waterloo, Ontario,
region would save transport-related emissions equivalent to nearly 50,000
metric tons of CO2, or the equivalent of taking 16,191 cars off the road.

What's "Local"?

But what exactly is "local food" in the first place? How local is local?

One problem with trying to determine whether local food is greener is that
there's no universally accepted definition of local food. Alisa Smith and
J.B. MacKinnon, authors of The 100-Mile Diet, write that they chose this
boundary for their experiment in eating locally because "a 100-mile radius
is large enough to reach beyond a big city and small enough to feel truly
local. And it rolls off the tongue more easily than the ‘160-kilometer
diet.'" Sage Van Wing, who coined the term "locavore" with a friend when
she was living in Marin County, California, was inspired to eat local after
reading Coming Home to Eat, a chronicle of author Gary Paul Nabhan's own
year-long effort to eat only foods grown within 250 miles of his Northern
Arizona home. She figured that if Nabhan could accomplish that in the
desert, she could do even better in the year-round agricultural cornucopia
that is Northern California, so she decided to limit herself to food from
within 100 miles.

There's some evidence that a popular understanding of local food is, at
least in some places, coalescing around this 100-mile limit. A 2008 Leopold
Institute survey of consumers throughout the United States found that
two-thirds considered local food to mean food grown within 100 miles.
Still, a variety of other definitions also persist. Sometimes local means
food grown within a county, within a state or province, or even, in the
case of some small European nations, within the country. In the United
Kingdom, reports Tara Garnett of the Food Climate Research Network, "on the
whole, organizations supporting local are now less likely to put numbers on
things." Meanwhile, rural sociologist Clare Hinrichs, of Pennsylvania State
University, has found that in Iowa local has shifted from signifying food
grown within a county or a neighboring one to food grown anywhere in the
state. For some in the agricultural community, promoting and eating "local
Iowa food" is almost a kind of food patriotism, aimed at counteracting the
forces of globalization that have put the state's family farmers at risk.

All of those are perfectly valid ways of thinking about local. But they
don't have all that much to do with environmental costs and benefits.

Tradeoffs

In any case, warns Pirog, food miles/kilometers don't tell the whole story.
"Food miles are a good measure of how far food has traveled. But they're
not a very good measure of the food's environmental impact."

That impact depends on how the food was transported, not just how far. For
example, trains are 10 times more efficient at moving freight, ton for ton,
than trucks are. So you could eat potatoes trucked in from 100 miles away,
or potatoes shipped by rail from 1,000 miles away, and the greenhouse gas
emissions associated with their transport from farm to table would be
roughly the same.

The environmental impact of food also depends on how it is grown. Swedish
researcher Annika Carlsson-Kanyama led a study that found it was better,
from a greenhouse-gas perspective, for Swedes to buy Spanish tomatoes than
Swedish tomatoes, because the Spanish tomatoes were grown in open fields
while the local ones were grown in fossil-fuel-heated greenhouses.

That seems obvious, but there are subtler issues at play as well. For
example, Spain has plenty of the warmth and sunshine that tomatoes crave,
but its main horticultural region is relatively arid and is likely to
become more drought-prone in the future as a result of global climate
change. What if water shortages require Spanish growers to install
energy-intensive irrigation systems? And what if greenhouses in northern
Europe were heated with renewable energy?

Perhaps it's inevitable that we consumers gravitate to a focus on food
miles-the concept represents the last step before food arrives on our
tables, the part of the agricultural supply chain that's most visible to
us. And indeed, all other things being equal, it's better to purchase
something grown locally than the same thing grown far away. "It is true
that if you're comparing exact systems, the same food grown in the same
way, then obviously, yes, the food transported less will have a smaller
carbon footprint," Pirog says.

But a broader, more comprehensive picture of all the tradeoffs in the food
system requires tracking greenhouse gas emissions through all phases of a
food's production, transport, and consumption. And life-cycle analysis
(LCA), a research method that provides precisely this "cradle-to-grave"
perspective, reveals that food miles represent a relatively small slice of
the greenhouse-gas pie.

In a paper published last year, Christopher Weber and H. Scott Matthews, of
Carnegie Mellon University, wove together data from a variety of U.S.
government sources into a comprehensive life-cycle analysis of the average
American diet. According to their calculations, final delivery from
producer or processor to the point of retail sale accounts for only 4
percent of the U.S. food system's greenhouse gas emissions. Final delivery
accounts for only about a quarter of the total miles, and 40 percent of the
transport-related emissions, in the food supply chain as a whole. That's
because there are also "upstream" miles and emissions associated with
things like transport of fertilizer, pesticides, and animal feed. Overall,
transport accounts for about 11 percent of the food system's emissions.

By contrast, Weber and Matthews found, agricultural production accounts for
the bulk of the food system's greenhouse gas emissions: 83 percent of
emissions occur before food even leaves the farm gate. A recent life-cycle
analysis of the U.K. food system, by Tara Garnett, yielded similar results.
In her study, transport accounted for about a tenth of the food system's
greenhouse gas emissions, and agricultural production accounted for half.
Garnett says the same general patterns likely also hold for Europe as a
whole.

There's Something about Dairy

The other clear result that emerges from these analyses is that what you
eat matters at least as much as how far it travels, and agriculture's
overwhelming "hotspots" are red meat and dairy production. In part that's
due to the inefficiency of eating higher up on the food chain-it takes more
energy, and generates more emissions, to grow grain, feed it to cows, and
produce meat or dairy products for human consumption, than to feed grain to
humans directly. But a large portion of emissions associated with meat and
dairy production take the form of methane and nitrous oxide, greenhouse
gases that are respectively 23 and 296 times as potent as carbon dioxide.
Methane is produced by ruminant animals (cows, goats, sheep, and the like)
as a byproduct of digestion, and is also released by the breakdown of all
types of animal manure. Nitrous oxide also comes from the breakdown of
manure (as well as the production and breakdown of fertilizers).

In Garnett's study, meat and dairy accounted for half of the U.K. food
system's greenhouse gas emissions. In fact, she writes, "the major
contribution made by agriculture itself reflects the GHG [greenhouse gas]
intensity of livestock rearing." Weber and Matthews come to a similar
conclusion: "No matter how it is measured, on average red meat is more
GHG-intensive than all other forms of food," responsible for about 150
percent more emissions than chicken or fish. In their study the
second-largest contributor to emissions was the dairy industry.

Nor are these two studies unique in their findings. A group of Swedish
researchers has calculated that meat and dairy contribute 58 percent of the
total food emissions from a typical Swedish diet. At a global level, the UN
Food and Agriculture Organization has estimated that livestock account for
18 percent of all greenhouse gas emissions-more even than all forms of
fossil fuel-based transport combined.

"Broadly speaking, eating fewer meat and dairy products and consuming more
plant foods in their place is probably the single most helpful behavioral
shift one can make" to reduce food-related greenhouse gas emissions,
Garnett argues.

Weber and Matthews calculated that reducing food miles to zero-an
all-but-impossible goal in practice-would reduce the greenhouse gas
emissions associated with the food system by only about 5 percent,
equivalent to driving 1,000 miles less over the course of a year. By
comparison, replacing red meat and dairy with chicken, fish, or eggs for
one day per week would save the equivalent of driving 760 miles per year.
Replacing red meat and dairy with vegetables one day a week would be like
driving 1,160 miles less. "Thus," they write, "we suggest that dietary
shift can be a more effective means of lowering an average household's
food-related climate footprint than ‘buying local.'"

However, Weber acknowledges, "these calculations were done assuming that
local foods are no different than non-local foods." And that's not always
the case. For example, local-food advocates also emphasize eating seasonal
(often meaning field-grown) and less-processed foods. Those qualities,
along with shorter distances from farm to table, will also contribute to
lower emissions compared to the "average" diet.

Food marketed in the local food economy-at farmers' markets and through
community-supported agriculture (CSA) schemes-is frequently also organic.
Organic food often (though not always) is associated with lower greenhouse
gas emissions than conventionally grown food, because organics don't
generate the emissions associated with production, transport, and
application of synthetic fertilizers and pesticides.

Organic food also has other environmental benefits: less use of toxic
chemicals promotes greater farmland biodiversity, and organic fields
require less irrigation under some conditions. Because local food is so
frequently talked about in terms of food miles, its environmental benefits
have largely been couched in terms of greenhouse gas emissions. But food's
carbon footprint "can't be the only measuring stick of environmental
sustainability," notes Gail Feenstra, a food systems analyst at the
University of California at Davis Sustainable Agriculture Research and
Education Program.

Finally, farmers who market locally are often relatively small in scale,
and can more feasibly adopt environmentally beneficial practices such as
growing a diversity of crops, planting cover crops, leaving weedy field
borders or planting hedgerows that provide a refuge for native
biodiversity, and integrating crop and livestock production. In short,
Weber says, "the production practices matter a lot more than where the food
was actually grown. If buying local also means buying with better
production practices then that's great, that's going to make a huge
difference."

Of course, the relationship between local food marketing and sustainable
agricultural practices is far from perfect. A small farmer can still spray
pesticides and plow from road to road. Not all farmers-market vendors are
organic. Clare Hinrichs, who calls herself an "ardent" farmers-market
shopper, nevertheless acknowledges that "the actual consequences-both
intended or unintended-[of local food systems] haven't really been all that
closely or systematically studied."

How Green Is My Valley?

So, is local food greener? Not necessarily. But look at the question from
the opposite direction: if you're a consumer interested in greener food,
the local food economy is currently a good place to find it. By the same
token, a farmer who sells in the local food economy might be more likely to
adopt or continue sustainable practices in order to meet this customer
demand. If local food has environmental benefits, they aren't all-or
perhaps even mainly-intrinsic to local-ness. Or, as Hinrichs has written,
"it is the social relation, not the spatial location, per se, that accounts
for this outcome."

For local food advocates like Sage Van Wing, that interaction between
producer and consumer, between farmer and eater, is precisely the point.
Regarding food miles, Van Wing says, "I'm not interested in that at all."
For her, purchasing an apple isn't just about the greenhouse gas emissions
involved in producing and transporting the fruit, "it's also about how
those apples were farmed, how the farm workers were treated"-a broad array
of ecological, social, and economic factors that add up to sustainability.
Interacting directly with the farmer who grows her food creates a "standard
of trust," she says.

Christopher Weber, who followed a vegan diet for 10 years and calls himself
"somewhat of a self-proclaimed foodie," agrees: "That's one thing that's
really great about local food, and one of the reasons that I buy locally,
is because you can actually know your farmer and know what they're doing."

Van Wing says that her approach to local food has evolved over time-she
started out trying to eat within a 100-mile radius, but now she simply
tries to get each food item from the closest source feasible. Foods that
can't be grown nearby are either rare treats or have disappeared from her
diet altogether. "I just don't do things that don't make sense," she says.
Her statement echoes journalist and sustainable-agriculture guru Michael
Pollan, who in his recent book In Defense of Food offers a common-sense
guide to eating ethically and well: "Eat food. Not too much. Mostly
plants." You could sum up the ecological case for eating locally by adding
one more sentence: "Mostly what's in season and grown not too far away."

Yet there are limits to this common-sense approach. In many areas, the
climate is such that eating local, seasonal, field-grown produce would be a
pretty bleak proposition for much of the year. Large concentrations of
people live in areas not suited to growing certain staple crops; it's one
thing to forego bananas, but quite another to give up wheat. And population
density itself works against relocalization of the food system. Most of the
land within 100 miles of large cities such as New York is itself very built
up; where will the farmland to feed us all locally come from? (By the same
token, that very situation makes preservation of what farmland remains all
the more important, a goal that buying from local farmers can help
advance.)

In this sense, life-cycle analyses of the current food system offer a
paradoxically hopeful perspective, because they suggest that, if the goal
is to improve the environmental sustainability of the food system as a
whole, then there are a variety of public policy levers that we can pull.
To be sure, promoting more localized food production and distribution
networks would reduce transport emissions. But what if a greater investment
in rail infrastructure helped to reverse the trend toward transporting more
food by inefficient semi-truck? What if fuel economy standards were
increased for the truck fleet that moves our food? Or, to name one
encompassing possibility, what if a carbon-pricing system incorporated some
of the environmental costs of agriculture that are currently externalized?
Local food is delicious, but the problem-and perhaps the solution-is
global.