By Elizabeth Weise, USA TODAY
With Americans looking to reduce their "carbon footprints," food seems an obvious place to start.
Choosing a diet with a smaller carbon footprint means choosing foods that are processed in ways that emit less carbon dioxide — a heat-trapping "greenhouse" gas — into the atmosphere. In general, experts say, it breaks down to these guidelines:
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•Cut down on meat. "That doesn't mean never eat meat, it means eat less of it," says Gail Feenstra, a food systems analyst at the University of California-Davis Agricultural Sustainability Institute.
Meat is less efficient because we eat the animal that eats the grain instead of eating the grain ourselves. It takes about 15 pounds of feed to make 1 pound of beef, 6 pounds of feed for 1 pound of pork and 5 pounds of feed for 1 pound of chicken, the Department of Agriculture estimates. For catfish, it's about 2 pounds of feed per pound of fish.
Add to the feed the cost of raising, transporting and producing cattle, and beef is by far the least energy-efficient meat. Nathan Fiala, a doctoral candidate in environmental economics at the University of California-Irvine, estimates it requires about 15 pounds of carbon dioxide to produce 1 pound of beef.
"A family of four that gives up eating beef one day a week has basically traded in their pickup for a Prius," he says.
•Eat what's in season. In winter, most produce is trucked in from Mexico and Central America or comes from Florida or heated greenhouses in Canada, Feenstra says.
•The less processed, the better. Boil a potato instead of buying au gratin dried potatoes in a box. Make oatmeal instead of eating frozen waffles. Eat an apple instead of a fruit snack bar.
•Organic is good but not always best. In general, organic foods grown locally have the most gentle environmental footprint, Feenstra says. In addition to the carbon savings in transportation, such foods rely on animal manure as fertilizer. Most conventional fertilizers rely on ammonia made from natural gas. One ton of fertilizer requires about 33,000 cubic feet of natural gas.
But the carbon-footprint benefits of organic foods become less clear over larger distances because of the efficiency of the nationwide distribution systems for mass-produced foods.
On its own, a tomato — organic or not — that comes from 1,500 miles away seems more wasteful than one that comes from 60 miles away, says James McWilliams, an agricultural historian at the University of Texas-Austin. "But that comparison is meaningless unless you say how many came in each shipment and how many gallons of fuel did it take for each tomato," says McWilliams, whose Just Food: How Locavores Are Endangering the Future of Food and How We Can Truly Eat Responsibly will be published this year.
•Don't drive far to shop. How far people travel to buy their groceries can overshadow all previous stages of a food's life cycle.
"If you bought cherries from a store that were grown in your area, but you had to travel 10 miles one way to get to the store and didn't do anything on the way, they'd actually have the same carbon footprint as if you ate cherries that were flown in," says Laura Stec, co-author of Cool Cuisine: Taking the Bite Out of Global Warming.
•Buy only what you need. "If you buy things and then let them rot in your refrigerator, all of the greenhouse emissions throughout the supply chain that went into producing and storing and processing them are a complete waste," Feenstra says.
At least throw them into the compost bin rather than the trash, "so the nutrients are recycled back into your garden," she says.
Start with small steps in reducing your environmental footprint, because "if it ain't fun, it won't get done," Stec says. "We don't want to turn the whole food system into just taking a pill because it's the lowest carbon footprint, for heaven's sake!"
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