The Climate Diet
What we eat affects greenhouse gas emissions — and the trend is encouraging.
Changing dietary patterns in the United States are leading to lower emissions of food-related, climate-warming gases, and half of the reduction can be attributed to eating less beef. The intriguing findings come from a UW study recently published in the Journal of Cleaner Production.
Every choice we make as consumers has a climate impact, which is often measured in terms of its “carbon footprint” — that is, the amount of greenhouse gases emitted in the process of producing a good or providing a service.
“The greenhouse gases of our food system are one of the largest portions of our footprint as a nation,” says Clare Bassi MS’21, who led the study.
Globally, food systems contribute about one quarter of all human-caused greenhouse gas emissions. That includes emissions associated with food production, processing, transportation, cooking, and waste. Bassi focused on what individuals can most easily control: what they choose to eat. She analyzed eating habits reported by more than 39,000 U.S. adults in a national survey from 2003 to 2018 and calculated the average daily greenhouse gas emissions associated with diet. Different foods have very different environmental impacts: animal products and processed foods are often much more carbon-intensive than minimally processed and plant-based foods.
In just 15 years, the carbon footprint of the U.S. diet fell by more than 35 percent. Lower consumption of beef, dairy, chicken, pork, and eggs accounted for more than 75 percent of the observed diet-related carbon dioxide savings during the study period; beef alone was responsible for nearly half of the drop.
“The trend is quite exciting,” Bassi says. “Over the study period, national greenhouse gas savings from dietary changes alone are roughly equivalent to offsetting emissions from every single passenger vehicle in the country for nearly two years.”
She also examined trends based on demographic factors, such as sex, age, household income, race, and ethnicity. Every subgroup she analyzed showed a 30 to 50 percent reduction in diet-related greenhouse gas emissions.
These positive trends are encouraging, she notes, but Americans are still exceeding our fair share of food-related emissions compared to other parts of the world: the average U.S. diet-related carbon footprint in 2018 was still nearly twice as high as global targets for minimizing global warming.
“People’s actions are making a difference,” Bassi says, “but we still have a long way to go.”
Published in the Fall 2022 issue