The provision of information about transport‐related carbon dioxide (CO2) emissions to the traveler can be seen as an instrument to increase the likelihood of more sustainable choices being made by individuals. However, as transport‐related CO2 emissions are largely seen as a ‘social’ cost rather than a ‘private’ cost to the individual, the behavioral engagement with and response to information on environmental effects of travel choices may be limited. It is argued that framing, studied in a range of contexts, can be used to enhance the evaluation of choice attributes and promote more sustainable choices. An experiment is reported that examines the effect of valence framing of amounts of CO2 emissions on the perceived differences between alternative amounts. Through the use of positive and negative terms, the information is framed to focus attention either on the potential of a travel mode to provide environmental benefit (positive frame) or on its potential to reduce environmental loss (negative frame). Survey participants’ estimates of CO2 amounts were compared for positive and negative framing of the same information using an ordered logit model. The findings imply that negative framing is more effective than positive framing in highlighting differences between CO2 amounts of alternative travel modes and therefore is likely to influence travel‐related choices.
