CO2 data influence eating behavior

25 Jan 2023

A field trial has shown that labeling the carbon footprint of food prompts people to eat more sustainably.

Visitors to canteens pay attention to information on climate-friendly nutrition, an experiment at the LMU shows. | © picture alliance / SZ Photo | Florian Peljak

Labeling the carbon footprint of food prompts people to eat more sustainably: This was the key finding for TRR 266 Accounting for Transparency researchers from LMU Munich, HU Berlin and Aalto University in Finland in a recent field trial. How the information is presented turned out to be the critical factor: The effect was greatest when CO2 information was visualized as traffic light colors or displayed in the form of cost to the environment.

The ten-day field trial was conducted at one of the Munich Student Union’s largest canteens: the one in Leopoldstrasse. During the experiment, more than 8,000 visitors to the canteen saw not only the usual menu information (such as the prices and main ingredients of each dish), but also details of the carbon footprint.

It depends on the form used to present the CO2 information

“Our study shows that presenting emissions data reduces demand for CO2-intensive dishes such as meat and fish, thereby reducing the overall CO2 footprint of the selected meal,” explains Joachim Gassen, Professor of Financial Accounting and Auditing at the Humboldt University (HU) in Berlin.

The form used to present the CO2 information was changed once a day during the trial period to see which had the greatest influence on consumers’ behavior. Some visitors, for instance, were informed of the environmental cost of their lunch in euro terms. On displays, others saw how much of their daily carbon budget was taken up by the meal they chose. Still others were informed of the CO2 emissions (in grams) caused by the given meal.

These details were flanked by traffic-light-based color coding (in green, yellow and red). The most powerful effect was achieved when visitors learned the cost (in euros) of the environmental damage caused by their lunch. In this way, as much as nearly ten percent fewer CO2 emissions were caused by meals purchased than when no information about CO2 emissions was provided.

A starting point for government agencies and companies to support more sustainable behavior

“Our experiment makes it clear that information about the carbon footprint can lead to a change in consumers’ behavior. This insight in turn can help government agencies and the business community to adopt suitable measures for a more sustainable future,” says Thorsten Sellhorn, Professor of Account, Auditing and Analysis at LMU. “For example, companies could make a voluntary decision to display CO2 information for food and for other products and services.”

The experiment was very important not only to the team of researchers, but also to the canteen management: “Sustainability and environmental awareness are important values to which we attach great importance in the running of our canteens. So, we were only too glad to support this project,” says Ralf Daumann, Head of University Catering at the Munich Student Union.

For more information about the study and to use the accompanying video and photographic materials, please visit the website of the Accounting for Transparency Collaborative Research Center: Can Carbon Footprint Information Influence Consumer Choice?

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