Friday, May 1, 2009

We air what we eat

There are many reasons to eat locally grown foods: to support local agriculture, buy the freshest food, and reduce energy use and greenhouse gases associated with food transportation, among others. But two researchers have recently shown that the average American can reduce greenhouse gas emissions even more by eating less red meat and dairy.

Christopher Weber and Scott Matthews of Carnegie Mellon did a comprehensive analysis of the amount of greenhouse gases emitted by various aspects of food production and transport for the journal Environmental Science and Technology. Although food travels long distances, 83% of the greenhouse gases associated with food are emitted during its production. Each dollar spent on red meat and dairy products, because of the amount of grain and land required to produce them and the amount of methane cows produce, results in about 2 1/2 to 3 times more greenhouse gases than each dollar spent on chicken, fish, eggs, cereals, and other foods. Because of these facts, skipping dairy and/or meat one day a week would have the same impact as buying all your food locally. So in addition to buying as much locally-grown food as possible, reducing our red meat and dairy consumption can have a big effect on our carbon footprint. There are many variables in this equation, including whether your beef is grass-fed or grain-fed (grass-fed has less impact due to fossil fuel use in grain production) and whether you eat meat or dairy at all, but these values hold true in general for the US population (and almost surely for other nations as well). Whether or not you eat meat or dairy, reducing your consumption of produce that's traveled a long distance, which is usually true of out of season produce, can reduce carbon emissions significantly. For a good summary of the article, see The Daily Score blog here.

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