Fighting Global Warming with Food

Low-carbon choices for dinner

Posted: 24-Jul-2007; Updated: 28-Jul-2009

There are lots of ways Americans can help fight climate change and reduce U.S. dependence on foreign oil. Buying a car or truck with better gas mileage. Using compact fluorescent bulbs. For those who choose it, even eating just a little less meat can help.

Why food choices affect climate change

Farmers are a critical part of our economy. They not only feed us, they’re also at the frontline of conserving America’s environmental resources and fighting global warming.
Just as with any other business, farming requires burning fossil fuels to make fertilizer, run tractors and process and transport food. It takes many calories of grains to make one calorie of meat, and animals and manure produce greenhouse gases like methane and nitrous oxide. As a result, producing meat emits more greenhouse gases than growing crops.

You don’t have to be a vegetarian to make a difference

Even small dietary changes can make a big difference.
If every American skipped one meal of chicken per week and substituted vegetables and grains, for example, the carbon dioxide savings would be the same as taking more than half a million cars off of U.S. roads. And speaking of cars, it takes fuel to transport food, so buying from local farmers and ranchers cuts emissions even if you don’t cut out any meat.

Equivalent emissions savings from weekly dietary changes

If every American had one meat-free meal per week, it would be the same as taking more than 5 million cars off our roads. Having one meat-free day per week would be the same as taking 8 million cars off American roads.

The details—how were these savings calculated?

These calculations are based on a recent paper by researchers at the University of Chicago.

All emissions savings are relative to an “average American diet” (according to data from the UN, 3,774 calories of food are produced per American per day, with 27.7% calories from animal-based products, of which 54% are meats, 41% dairy and 5% eggs). In this diet Americans eat, on average, 199 calories per day from chicken, 209 from pork and 119 from beef.
The “less chicken,” “less pork” and “less beef” diets assume that every American eats one day’s worth less chicken, pork or beef per week. The “one meal with no meat” diet assumes that every American eats 350 fewer calories from meat each week (this is about one-third the average daily meat intake, or one meal’s worth of meat).
For the “one meal with no meat” and “one day with no meat”, avoided calories from assorted meats are in the same proportions as they are consumed in the mean American diet. In all diets, dairy and egg intake remains unchanged and calories frommeat are replaced with calories from plant-based foods.
The emissions savings from these dietary choices are calculated assuming that themeat not consumed by Americans is also not consumed by others outside the U.S., and thus results in a decrease in overall meat production. To the extent that American consumption were replaced by foreign consumption, the overall GHG emission reductions estimated here would be smaller on a global scale.
CO₂ emissions are based on previously published values of the amount of fossil fuel used (and thus the amount of CO₂ emitted) to produce different types of foods. Non-CO₂ emissions (given as “CO₂ equivalents”) from animal-based foods (eggs, dairy, and various meats) are based on data from the U.S. Department of Energy. Only methane and nitrous oxide from animal digestion and manure management are considered. The calculation assumes there are no non-CO₂ emissions from crop production.
Nationwide emissions savings and their car equivalents are calculated assuming 300 million Americans and average car emissions of 35 pounds of CO₂ per day.

Sources

G Eshel and PA Martin, “Diet, energy, and global warming,” Earth Interactions 10, Paper No. 9 (2006): 1-17.
www.census.gov/main/www/popclock.html and www.fightglobalwarming.com/page.cfm?tagID=263

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