While many people know about the ethical reasons to stop eating meat, a new Yale report shows that most Americans are unaware of the environmental impact they could have by adopting a more plant-based diet.

Researchers at the Yale School of Forestry and Environmental Studies conducted a national survey-based study on the connection between global warming and the American diet. The survey, which solicited over 1,000 responses, asked questions ranging from the composition of people’s diets to their knowledge of how diet impacts climate change. The survey was administered in December of last year, and the report was released on Feb. 13.

“Food waste is a big piece of the overall contribution of the food system to greenhouse gases,” said Anthony Leiserowitz, an FES senior research scientist and one of the principal investigators on the report. “Here in the United States, the average American throws away about a third of the food they buy, so that basically means that for every three bags of groceries that somebody buys, it’s almost like they’re throwing one of them out.”

Food production is a leading contributor to greenhouse gas emissions, accounting for 30 percent of all emissions. Livestock production contributes most to emissions, while growing fruits and vegetables contributes least.

Food waste is also a major contributor to greenhouse gases. The report explains that 56 percent of Americans never compost their food waste. Changing this habit would have a major impact on the environment.

“They’re putting [their food] in the trash which means it ends up usually in a landfill, where it decomposes and turns into methane, and methane is a super potent greenhouse gas […] much more heat-trapping than regular, old carbon dioxide,” said Leisowitz.

The report showed that although only 4 percent of Americans are vegan or vegetarian, 94 percent said they are willing to eat more fruits and vegetables, and 55 percent said they would be open to consuming plant-based meat alternatives. According to the report, this discrepancy stems from a general lack of information on the environmental impact of what they eat.

“[Americans] don’t really hear about it in the media, and most Americans aren’t looking for information about the environmental impact of different foods, and most are also not talking to their family and friends about the environmental impact of their food,” said Matthew Ballew, another principal investigator for the report, who completed his postdoctoral fellowship at Yale last year.

According to the report, 64 percent of Americans said they have never been asked to eat more plant-based foods, and 51 percent said they would if they were more informed about the environmental benefits.

Though environmental considerations play a large role in people’s decisions regarding their diet, the report concludes that people are more interested in their health.

“The number one reason why people are interested in adopting a plant-based diet […] is for their own health,” said Leisowitz.

This report is unique both in its comprehensive scope and its emphasis on public opinion. Ballew said that it would be worth administering the survey every other year to trace how perception of diet and global warming changes over time, both in the United States and other parts of the world. “It would be incredibly valuable to look at other countries and their perceptions of food and climate change and what actions they’re taking,” he said.

The research was conducted by the Yale Program on Climate Change Communication, which was founded in 2005.

Charlotte Zimmer | charlotte.zimmer@yale.edu