Q. My sister, a vegetarian, says that swearing off of meat does more good for the environment than shopping at the farmers market. I say buying all of our food from local farms, including beef and pork, has more impact. Who’s right?

– Luisa, ME

A. Well, this isn't to say that you have to go veggie to be green, but actually Luisa, your sister is right. Sure, buying a pound of grass-fed, organic ground beef from a farm just fifty miles from your home is undoubtedly better than, say, buying a pound of factory-farmed hamburger from a store where it might have been imported from 1,000 miles away.

But a recent study from Carnegie Mellon found that “food miles” — the distance that food travels between the farm and your plate—accounted for only 11 percent of the carbon footprint left by the average household’s groceries. That means that in the larger debate you and your sister were having, reducing meat consumption trumps local sourcing. Producing the food in the first place is what sucks up a lot of energy and produces emissions — and meat is the most CO2-intensive food item you can possibly go for.

Besides the energy and transportation involved in feeding and housing the animals, there are also the emissions produced by the cows themselves to consider. Cattle and other ruminants exhale nitrous oxide, plus, their ‘output’ gives off methane. Both nitrous oxide and methane leave a substantial climate footprint, explains Chris Weber, PhD, the study’s author.

So when you crunch the numbers, as Weber did, it turns out that going veggie, or even just sticking with poultry and fish, just one day a week makes as much impact as getting your entire menu locally. That’s not to say there aren’t plenty of good reasons to shop at the farmers’ market. Less is still better than more when it comes to food miles, and farmers’ market vendors often stick to organic and other eco-friendly methods. Bottom line: DO BOTH. To really reduce your impact, reduce your meat consumption and buy from sustainable, local farms.

Story by Sarah Schmidt. This article originally appeared in Plenty in June 2008. This story was added to MNN.com.

Copyright Environ Press 2008