Full lifecycle greenhouse gas emissions from common proteins and vegetables. Copyright © Environmental Working Group, www.ewg.org. Reprinted with permission.
Assistant Professor of Environmental Health and Exposure Disparities, Harvard T. H. Chan School of Public Health
Gary Adamkiewicz, instructor of From Farm to Fork: Why What You Eat Matters, discusses the nuances of food miles and their impact on our climate.
I am dependent on foreign oil.
Not that kind. Olive.
Whether it’s grapes from Chile or olive oil from Italy, odds are, you consumed something today that logged more than 1,000 miles from the farm to your fork. Concerns about the effects of this transport on our climate have inspired many to embrace their inner “locavore” by limiting the food miles on their dinner plate.
Will buying local food slow climate change?
The short answer is that buying local food is a good principle, but not a universal rule. Some of the biggest climate effects can happen before a corn cob leaves the farm or a steer leaves the feedlot.
To quantify this, we need to account for all steps in the lifecycle of our food, from cradle to grave. Transportation is just one slice of that lifecycle. The figure below, based on an analysis by the Environmental Working Group (EWG), illustrates this fact by separating the effect of production from emissions once the food leaves the farm.
Lamb, beef, and pork are among the biggest climate offenders. And these effects are not driven by their transport. In fact, a 2013 United Nations report showed that globally, livestock represent 14% of all greenhouse gas emissions. This would be comparable to emissions from cars, trucks, buses and other transport combined.
For the climate, your dinner might increase your carbon footprint more than your driving.
What’s driving production emissions?
For produce, production emissions can include the energy that goes into chemical fertilizers and pesticides, the diesel-powered farm equipment, or greenhouses heated to extend the growing season.
For livestock, it’s all that and more because we grow large quantities of feed grain. It can take more than 10 pounds of grain to produce one pound of beef. If that grain is energy-intensive, that beef is going to be much more so. And by the way, cows and other ruminant animals also belch methane, which has 21 times the greenhouse potential of carbon dioxide.
Global Climate Change