Students reduce carbon footprints after studying food system’s environmental impact

May 9, 2019

By UCLA Samueli Newsroom

A UCLA-led study published in the journal Climatic Change found that college students who learned more about the environmental impact of their food choices made dietary changes that are better for the environment.

According to Jennifer Jay, the UCLA professor who led the research, if the entire U.S. population made the same types of changes in their diets, the reduction in greenhouse gas emissions, the major cause of climate change, would be significant.

“If the small changes we observed are extrapolated across the United States, the savings in greenhouse gases would represent one-third of the reduction prescribed in the 2013 President’s Climate Action Plan,” she said.

Previous research on the connection between food and climate change have only offered projections of what the possible impact would be if a large group of people shifted their diets. The UCLA study is the first to use real-world data.

Researchers compared the eating habits of UCLA first-year students in two courses for a period spanning two consecutive academic quarters, or about 23 weeks. Half of the students were enrolled in a class focused on the link between food and the environment; the other half were in a course about covering cosmology and evolution. Students in both courses were surveyed on their diets at the beginning and end of the research period.

The researchers found that students in the course about food decreased their weekly consumption of beef by 28% — about one serving per week. That, along with other changes in what they ate, resulted in a dietary carbon footprint that was 16% lower for those students than for the students in the cosmology course. A person’s dietary carbon footprint includes all of the greenhouse gases generated in the production of the food they eat.

(The study also found that women in the cosmos course lowered their beef consumption by a half serving per week, while men in that course increased their beef consumption by one-and-a-half servings per week.)

“There has been a growing public awareness that individual choices on energy use — from driving electric cars, to turning down thermostats to installing solar roofs — can have a positive impact on the environment,” said Jay, who co-taught the course on food and the environment, and is a UCLA professor of civil and environmental engineering at the UCLA Samueli School of Engineering. “But we don’t have the same level of public awareness when it comes to what we eat, and our dietary choices can impact environmental health.

“This study shows for the first time that education can play an important and quantifiable role in mitigating climate change through even modest voluntary food shifts.”

Reducing beef consumption would help slow the rate of climate change because of livestock’s sizeable influence on greenhouse gas emissions. A 2013 United Nations study concluded that emissions from livestock make up 14.5% of the world’s human-caused greenhouse gas emissions — mostly due to methane, a potent greenhouse gas that cattle and other animals produce when they are digesting their food.

The study also found that women in the food science course increased their consumption of vegetables, eating an average of more than nine servings of vegetables a week, up from just over seven per week. Women in the other course reported eating between six and seven serving per week, both at the beginning and end of the study.

“While the students decreased consumption of certain animal products, the total protein levels remained the same for men and actually increased for women,” said Dr. Wendy Slusser, associate vice provost for the Semel Healthy Campus Initiative Center at UCLA and a co-author of the study. “In other words, the female students were replacing beef with other protein-rich foods, such as beans.”

Jay also has been teaching a seminar at UCLA that, in addition to covering the environmental impacts of food, also includes simple cooking demonstrations to show that eating a low-carbon-footprint diet can be both easy and affordable. Hannah Malan, a doctoral student at the UCLA Fielding School of Public Health and a co-author of the study, has already analyzed preliminary data on the eating habits of students taking that class.

“It looks like even small-scale and more practical interventions can still result in environmentally beneficial dietary changes that are similar to the ones we saw among students in the two-quarter course,” she said.

Jay is a member of the Menus of Change University Research Collaborative, which in tests at UCLA, UC Davis and Stanford University, is reviewing the effectiveness of the educational materials she has developed.

Among the study’s other authors are UCLA faculty members Anthony Friscia, Deepak Rajagopal and May Wang; UCLA staff members Raffaella D’Auria, J. Cully Nordby and Marc Levis; Andy Rice, a former UCLA postdoctoral scholar now at Miami University in Ohio; and Emily Wesel, a high school student who was a research intern in Jay’s lab. Other authors are from UC Santa Barbara and the Natural Resources Defense Council.

Jay, D’Auria, Nordby and Rajagopal are also members of the UCLA Institute of the Environment and Sustainability


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