The Locavore's Dilemma
In recent years many environmentalists have fixated on the notion of eating as close to home as possible. There are plenty of good reasons for doing so: preserving agricultural open space, supporting family farms, and keeping regional food traditions alive, to name a few. However, one of the most widely cited reasons--reducing greenhouse-gas emissions associated with transporting the food to market, sometimes known as "food miles"--may be greatly overstated.
According to a new study be Christopher Weber and H. Scott Matthews in Environmental Science and Technology, a much larger source of greenhouse emissions is the production phase--the fertilizers, feed, and other inputs it takes to produce the food. This accounts for 83 percent of the average U.S. household's carbon footprint for food consumption.
Transportation as a whole represents only 11% of life-cycle GHG emissions, and final delivery from producer to retail contributes only 4%. . . . [F]or the average American household, "buying local" could achieve, at maximum, around a 4-5% reduction in GHG emissions due to large sources of both CO2 and non-CO2 emissions in the production of food."
Sounds like bad news, right? Despair not! According to the authors' lifecycle analyses, it's far more important what one eats rather than how close it is:
Shifting less than 1 day per week's (i.e., 1/7 of total calories) consumption of red meat and /or dairy to other protein sources or a vegetable-based diet could have the same climate impact as buying all household food from local providers.
Put in other terms, eating totally local would result in GHG reductions equivalent to driving 1,000 miles less per year, while eschewing red meat for one day would be the same as driving 1,160 miles less. Meatless Monday, here we come!