U.S. household food purchasing a major source of greenhouse gas emissions

Creative commons: Scott Warman

U.S. household food purchasing a major source of greenhouse gas emissions

The United States emitted a little more than 5 billion metric tons of climate warming gases in 2013, ranking in the top five globally for per capita emissions and second to China in total emissions. Three big sources of emissions in the U.S. include activities integral to our daily lives: transportation, electricity, and industrial activity. We drive in cars, fly in airplanes, use electricity for heating, cooling, lighting, and electronics in our homes. All of these consumption activities generate greenhouse gases. Another integral part of our lives is food. Foods don’t cause emissions the same way a car or airplane does. There is no tailpipe on the hamburger you purchase at a restaurant. So it’s not surprising that people don’t think of food when they think of climate warming gases. 

By the time a food reaches you, climate warming gases have already been emitted (and are consequently “embedded” in it) as a byproduct of the processes involved in growing, processing, and distributing food. For example, the digestive processes of cows release methane, a potent greenhouse gas.  Restaurants use electricity to fire up the grill or to light the seating area. Determining the amount of embedded emissions generated along food’s complex journey is essential to finding ways to mitigate greenhouse gases produced by the food system. 

The goal of our recent research, published in the journal Food Policy, was to comprehensively estimate the embedded emissions caused by the massive supply chain that delivers food to U.S. households.  Emissions caused during agricultural production, in food processing, in transporting food on trucks, trains, ships, and airplanes, and from retail and restaurant activities were all included in our estimates. 

Results indicate that 16% of total U.S. greenhouse gas emissions in 2013 resulted from household food purchasing alone, which is equivalent to 900 million metric tons of carbon dioxide per year (roughly Germany’s total greenhouse gases in a year). 20% of food-related emissions for the average household came from one category: red meat.

Other key findings were that higher household food spending was associated with higher emissions, and that emissions generated by food purchases were higher for households with higher education levels and incomes. This presents an opportunity for mitigation in the food system: households with the most financial resources likely have the most flexibility to shift their food purchases towards more climate-friendly options.  

As noted by researchers who also study food system emissions, food has a short “lock-in” period, meaning we can change what we eat quickly. As consumers, we can take advantage of this convenient feature to immediately reduce our food-related emissions. Try buying less food and throwing less away. Or, try reducing (but not necessarily eliminating) red meat purchases in favor of healthy, plant-based options. Some of these changes, as emerging evidence suggests, may be better for your health and wallet, to boot. 

Now, eating is a pleasurable activity, so we are not suggesting that people stop enjoying what they eat. We are especially not suggesting that people sacrifice their calorie and nutrient needs in the name of climate mitigation. We are, however, suggesting that food consumption should be thought of like other consumption activity. The more you purchase or consume, the more natural resources you use and the more greenhouse gases you generate.  

To be sure, your choices alone won’t make the difference on climate change. But, there is some compelling evidence, nicely summarized in this recent article, that your choices may snowball into something more impactful. Your new climate friendly diet may inspire your friends or family to eat one less burger a week. In turn, they may inspire others to change, too. When social norms start to shift, real change is more likely to happen in the halls of Congress.