Can Social Comparisons and Moral Appeals Induce a Modal Shift Towards Low-Emission Transport Modes?

To reduce CO2 emissions, some companies have introduced mobility budgets that employees can spend on leisure and commuting trips, as an alternative to subsidized company cars. Given their novelty, little is known about how mobility budgets should be designed to encourage sustainable transportation choices. Since prices play a limited role in this subsidized setting, our study focuses on behavioral interventions. In a field experiment with 341 employees of a large German company, we test whether social comparisons, either in isolation or in combination with a climate-related moral appeal, can change the use of different means of transportation. We find strong evidence for a reduction in car-related mobility in response to the combined treatment, which is driven by changes in taxi and ride-sharing services. This is accompanied by substitution towards micromobility, i.e., transport modes such as shared e-scooters or bikes, but not towards public transport. We do not find robust evidence for effects of the social comparison alone. Furthermore, survey evidence suggests that effects may be driven by a climate-aware minority and that participants indeed felt a moral obligation to comply with the social norm. Our results demonstrate that small, norm-based nudges can change transportation behavior, albeit for a limited time.