Effects of emissions labels on consumer choice of lower-emission flights

Air travel generates disproportionate greenhouse gas emissions, without viable supply-side mitigation options. Demand-side measures, such as emissions information at the point-of-sale, are thus gaining interest. In a pre-registered experiment with a nationally representative sample (N = 1,000), we tested whether current emissions labelling systems shift consumers towards lower-emission flights. Participants were randomised to see either (i) no emissions information, (ii) absolute emissions values, (iii) absolute values with a relative emissions label or (iv) absolute values with a relative label and a contextual marker on the lowest-emitting flight (the number of trees needed to absorb the difference in emissions between this flight and the median). In the first task, participants selected hypothetical holidays from an online booking site. The study’s focus on environmental impact was concealed. Absolute emissions values had no effect, but the relative and ‘trees’ labels modestly increased low-emission flight selection (4-6%-points). In the second task, participants were instructed and incentivised to select the lowest-emission flight. Absolute emissions improved identification by over 40%-points, with no further benefit of additional labels. The relative labels caused some participants to choose higher-emitting flights (e.g., long-haul flights with large relative reductions). A final task measured comprehension of labels and showed widespread confusion: two-in-three misinterpreted the reference point for relative labels and few correctly identified the factors that are considered in label calculations. Overall, the findings imply that emissions labels, as currently implemented, are unlikely to reduce aviation emissions meaningfully and risk amplifying rather than correcting misperceptions by potentially greenwashing aviation.