You may have estimated your own carbon footprint, but do you know the footprint of that apple you’re about to buy?
Do you know its food miles?
The term food miles — the distance food travels from production to plate — was coined by a British professor in London in the 1990s. A related word emerged in 2003 when four women in California’s Bay Area declared themselves “locavores” — people who eat food grown within their locale.
The main idea: to ensure freshness, support local producers and slash the average number of miles food travels from farm to dinner table from an average of 1,500 to something like 56.
Locavore had legs. A mere three years later, it was The New Oxford American Dictionary’s 2007 word of the year. Trendy restaurants were quick to tout their use of locally grown food. New farmers’ markets sprouted, and old ones blossomed. Food miles and the benefits of keeping food production close to consumption became concepts worthy of study in agriculture and environmental studies programs throughout the country.
But locavore is not a new idea. Back in the old days, Grandma spent weeks putting up canned fruits and vegetables and kept a cellar for root crops. She was the ultimate locavore.
Grandma didn’t have much of a choice if she wanted to keep fruits and vegetables in her diet over the winter. Some might say the complexity of the food system and the choices we have today are part of the problem — not only in evaluating the increasing distances our food travels but in the larger picture of its carbon footprint, which really gets complicated.
A more pertinent measure of agriculture’s impact on the planet than food miles, some researchers say, is to look at greenhouse gas (GHG) emissions associated with the entire food delivery system.
Two researchers at Carnegie Mellon University in Pittsburgh found, while analyzing the whole food cycle — from production of fertilizer for crops to that steamed veggie on your plate — that food miles contributed about 11 percent of total GHG emissions. Production was responsible for about 83 percent of the total, and final delivery from producer to retailer was responsible for about 4 percent.
Authors Christopher L. Weber and H. Scott Matthews wrote in Environmental Science & Technology that different food groups have widely varying ranges of GHG intensity. Red meat, for example, is about 150 percent more GHG intensive than chicken or fish.
If you want to address global warming, they concluded, you would do better to modify your diet to limit red meat. Just shifting fewer than one day a week from red meat and dairy products to chicken, fish, eggs or a vegetable-based diet will result in more GHG reduction than buying all locally sourced food.
Talk about taking the air out of a locavore — how can not transporting food 1,500 miles, processing and packaging it and refrigerating and storing it for days have so limited an impact, one might ask?
One answer is that the Weber-Matthews study didn’t break down the 83 percent of production costs, and many of those costs fall when food is grown and sold locally and fall even more when it is grown organically.
The GHG emissions tally in the Weber-Matthews study included methane and nitrous oxide emissions from cattle operations — which, together, are much higher than carbon dioxide emissions. Also included were emissions from gas-fired power plants for nitrogenous fertilizer production and transportation.
This would not be a factor in an organic farm, say locavores (who tend to support organic farms, most of which produce their own fertilizers). They also could argue that the costs of refrigeration — both for transport and in the home — are less with locally purchased food, as are processing and packaging costs.
An Earth Policy Institute report released in 2005 analyzed energy use (as opposed to the broader analysis of GHG emissions). The study by Danielle Murray revealed growing food accounts for 21 percent of the 10 quadrillion Btu the U.S. food system uses each year. Murray breaks the remaining 79 percent into home refrigeration and preparation (a surprising 31 percent); processing (16 percent); transport (14 percent); packaging and restaurants (7 percent each); and food retail (4 percent).
Founded in 2001 by Lester Brown and Rhea Janise Kauffman, the Earth Policy Institute prepares studies and publishes books on sustainable systems with an emphasis on agriculture and renewable energy.
Janet Larsen, director of research for the organization, deems the Weber-Matthews report “an important contribution” to the food cycle debate, although she points out that the authors drew data from 1997 and noted in the study that food miles have increased since that time. Increasingly, she said, it’s becoming clear that the GHG emissions associated with eating high on the food chain are the main problem when considering global warming.
Like others studied on the topic, Larsen believes food miles still have a role to play in the general debate. “There’s so many reasons to go local, and food miles is one of them,” she said. “For many people, the bigger draw is knowing where your food is coming from — and also taste and nutrition values.”
Some are holding up the food miles concept to carbon footprinting and finding surprising dichotomies. The British Broadcasting Company recently posted a story by Caroline Stacey on its Web site that analyzed Britain’s food cycle — a third of the carbon footprint of United Kingdom households.
Stacey noted that one report suggested growing tomatoes in Spain and importing them by lorry is more energy efficient than growing them in a heated greenhouse in the U.K. Another study — by Lincoln University in New Zealand — “concluded that rearing and distributing British lamb produces more CO2 emissions than importing the meat 11,000 miles by sea.”
The reason: New Zealand farmers use more renewable energy and less fertilizer.
The Carbon Trust, a government-funded independent company in the U.K., has developed a label that will show carbon emission in grams. Walkers brand cheese and onion crisps are the first to be adorned, but smoothies are also being measured, and Stacey reported that it’s been shown that only a quarter of the carbon emission tally on a mango and passion fruit smoothie can be attributed to the fruits’ journey from India. (Food miles would be in the thousands.)
This would seem to jibe with the Weber-Matthew report and others in terms of carbon footprint since international transport has a relatively low percentage of the carbon footprint when considering overall costs of production. Unlike most fruit, mangoes don’t require air transport; they can come by boat, which releases about 0.2 per million ton-kilometer GHG emissions as compared to the 10 per million ton-kilometer attributed to air travel.
Amid all of this information, taking a trip to the grocery store can be a little disconcerting. The food cycle and its attendant costs are so complicated they would try the patience of Job.
What Can You Do?
Say you’re looking to lower your food’s carbon footprint.
You want to buy an apple. But fruit has a fairly high carbon footprint because of the need — with fresh and frozen produce — for refrigeration. The plus side with fresh fruit: no need for packaging or processing. Many apples readily available today are grown in New Zealand; you opt for the American apple, which only had to be trucked, not flown, saving big in food miles but not necessarily in carbon footprint. (The BBC story noted that although air-freighted produce accounts for less than 1 percent of total U.K. food miles, it is responsible for about 11 percent of the total GHG emissions.)
You also have been hungry for a good old hamburger. Do you buy the beef raised organically, frozen and shipped 2,000 miles? Or do you buy the conventionally raised beef that is freshly ground and comes from a few hundred miles away? Remember, organic growing has a lower carbon footprint, and refrigeration is expensive. Or do you skip that and go with chicken or tofu, as recommended by Weber and Matthews?
Months pass, and it’s winter. You’re really hungry for a cherry. You don’t want to buy those tempting cherries flown to California from New Zealand and trucked from there.
If you’re altruistic, you may shrug off the cost of air transport because New Zealand is generally more environmentally conscientious in agriculture and uses renewable energy.
Other factors come into play as well. About 1 million African farmers’ incomes are tied to global sales of fruits and vegetables. Do you really want to penalize the poorest producers in the global economy to lower your food’s carbon footprint? What do you suppose those African farmers’ carbon footprint is?
You could try a canned or frozen fruit grown on this continent, but you wouldn’t be saving a whole lot in GHG emissions because of the costs of processing, packaging and, for the frozen goods, constant refrigeration. (Don’t forget refrigeration is a key part of energy use, and trucking accounts for about 39 percent of the GHG emissions in the Weber-Matthews study.)
If you want to really get serious and eliminate the general confusion, you could be like Grandma and grow your own fruit and vegetables or buy them in bulk and can them yourself.
Of course, you’ll have to buy a whole lot of jars, prepare to pay a higher utility bill, acquire some new skills and take a month or more off from your job.
Did I say this was going to be easy?
Locavore or carbon footprint: Pick your passion.
Sign up for our free e-newsletter.
Are you on Facebook? Click here to become our fan.
