Carbon footprint labels involving traffic lights foster sustainable food choices

One reason consumers buy unsustainable products is that judging the environmental impact of food choices is very difficult. This study examines whether using carbon footprint labels to convey relevant impact information increases the tendency to choose low-carbon food items. In a pre-registered online experiment, 1,126 participants chose between low-CO2 and high-CO2 products 14 times (e.g., chili sin carne versus chili con carne or margarine versus butter). The two alternatives were either presented without labels (control), with a label communicating the food alternative's relative sustainability within its food category (traffic light), with a label communicating the absolute carbon emissions in kg CO2 (absolute), or with a label communicating both the relative sustainability and absolute carbon emissions (combined). The results show that the traffic light label and the combined label increased the chance of choosing a low-CO2 (versus a high-CO2) food item. There were no interactions between carbon footprint labels and environmental concern / cognitive reflection. Our research contributes to the discussion on the effectiveness and practical relevance of carbon footprint labels by testing a specific traffic light design and demonstrating the limited impact of communicating absolute carbon emissions.