(Bloomberg) -- Climate labels on fast-food menus can help steer people in the US away from ordering beef — the food with the worst impact on the climate —  and towards meals that are better for the planet, according to new research.

Food systems contribute roughly a third of global greenhouse gas emissions, and much of it coming from raising cows and other livestock. As people look for climate solutions to rapidly cut down their greenhouse gas emissions, “one of the biggest changes we can make is reducing the red meat we consume,” says Julia Wolfson, an associate professor at Johns Hopkins Bloomberg School of Public Health and one of the researchers behind the new study. (The Johns Hopkins Bloomberg School of Public Health is supported by Michael R. Bloomberg, founder of Bloomberg LP and Bloomberg Philanthropies.)

In search of ways to shift consumer behavior, Wolfson and colleagues at Johns Hopkins, Harvard University and the University of Michigan created an experiment to test two types of climate labels on fast-food menus. The researchers specifically targeted fast food because it’s a major source of beef consumption in the US. More than one-third of Americans consume fast food on a given day.

Using a large fast-food chain’s menu as a model, the researchers came up with three menu versions: one without climate labels, a second with red labels under every beef option noting “high climate impact,” and a third with green labels noting “low climate impact” under chicken, fish and vegetarian meals. Roughly 5,000 participants were randomly assigned to view one of the three menus and then prompted to select an item they would hypothetically like to order for dinner.

The group that avoided beef looked at menus with the high-impact label, with 61% of them ordering a more sustainable option, according to the study in the medical journal JAMA Open Network. More than half of people who saw the low-impact labels, 54.4%, made a more sustainable choice, and just less than half of those who saw no labels at all decided to avoid beef.“The main takeaway is that both labels effectively increased the proportion of participants who ordered a sustainable item,” says Wolfson, “but the most effective was the high climate impact label on the red meat item.”That finding "is consistent with previous research showing that negative-framed messages may be more influential than positive ones," says Lindsey Smith Taillie, a nutrition epidemiologist at the University of North Carolina at Chapel Hill who was not involved in the study. She cited research showing that labels on the front of  packages warning of "high in sugar" foods can lead to reduced consumption.Kristie Ebi, a climate and health professor at the University of Washington who was also not involved in the study, sees the result as a sign “that with more information, the American public could make better choices in terms of healthiness and in terms of sustainability.” More research is needed to determine the most effective climate labeling, and Ebi suggested looking to the history of warning labels on cigarettes which have since “been improved in terms of their effectiveness.” While the research suggests climate labels could help move the needle on eating more sustainably in a fast-food setting, it’s not definitive proof. “This was an online study with a hypothetical food choice,” says Wolfson. “It will be really important to see in the future if these results and the magnitude of these impacts would be replicated in real world settings where people are making real choices, they are spending their real money and they are then having to really eat the foods they select.”

The researchers also found that people who selected the non-beef or more sustainable option, regardless of the climate labels they saw, were more likely to view that choice as healthier — even if that wasn’t necessarily the case.  “It’s really important how we think about striking that balance when trying to nudge consumer behavior towards both more sustainable selections as well as healthier options,” says Wolfson.Ebi pointed out that none of the menu items in the labeling study were actually healthy, regardless of their climate impact.  “This suggests that fast-food restaurants need further encouragement to provide healthier food choices.”

©2022 Bloomberg L.P.