One Reason Eating Locally Won't Stop Global Warming, and 3 Reasons It Might

If I buy a bag of apples grown in an upstate New York orchard, their journey from the apple orchard to the fruit bowl on my Brooklyn countertop is much shorter than the trip taken by a bag of apples from New Zealand. So it stands to reason that they'd have a smaller carbon footprint, right?

Not necessarily.

Since the "eat locally" movement began to surge a few years ago -- "locavore" was the New Oxford American Dictionary's 2007 word of the year -- it's been tightly associated with stopping global warming. The connecting thread is "food miles": the distance food travels between producer and consumer, and how much greenhouse gas gets pumped into the atmosphere in the process.

But the data suggest that it's not how far my apple traveled, but how it got here, that makes the difference.

In a recent study of the "climate impact" of food miles, published this past spring in the scientific journal Environmental Science and Technology, researchers at Carnegie Mellon University did a full analysis of all the greenhouse gases emitted during every phase of growing and transporting foods eaten in the U.S. They did an input-output life cycle assessment, counting not just the carbon dioxide created when the food is shipped, but also all the greenhouse gases (including methane and nitrous oxide) pumped out by growing and harvesting the food -- right down to the fossil fuels used in the manufacture of tractors and fertilizers.

The Carnegie Mellon team concluded that farm production accounts for an overwhelming 83% of its global warming impact, while transportation accounts for only 11%. (That means about 0.89 metric tons of greenhouse gases, out of a total 8.1 metric tons of greenhouse gases that the average American household generates each year as a result of food consumption.)

Carnegie Mellon's Christopher Weber, the lead author of the study, suggested that the dietary change that can have the biggest effect on global warming is not eating local, but eating less meat -- something I've explored here on globalwarming.change.org as well.

So okay, a desire to cut your carbon footprint isn't de facto a good reason to favor local foods -- unless that food-from-far-away arrives via airplane. But here are a few non-scientific reasons eating locally can help stop global warming:

1. Buying your food from local producers helps strengthen the local and regional economy. Since local and state governments are, for now, the ones on the front lines of preparing for climate destabilization, setting up carbon credit auctions, and promoting sustainable communities, a strong local economy will ultimately contribute to funding those efforts.
2. Eating locally helps smaller farmers stay in business. So instead of sprouting homes and strip malls, which are likely to be net emitters of excess carbon, their land grows plants that take up carbon as they grow and release it when they are harvested. This is at essence a closed loop that releases no new carbon into the atmosphere (although external factors such as fuel for farm equipment, or pesticide and fertilizer use, can shift the balance).
3. Touchy-feely alert on this last one: Often eating more local foods means getting out into your community and talking with new people -- by joining a farm share, shopping at a greenmarket, or even growing your own in a shared garden. You may well make friends and acquaintances who share your values, and also share knowledge and ideas about living more sustainably.

Image source: U.S. Department of Agriculture, Agricultural Research Service