This paper compares the efficacy of two green nudges that aim to increase low-emission meal choices. The paper explores a direct approach through the use of displaying carbon emissions data (a green nudge) as well as an indirect approach of displaying nutrient data (a green nudge 'by proxy'). In the reported experiment, carbon footprint labelling outperformed the control group by 11.5 percentage points whereas nutrient data labelling outperformed the control group by 24 percentage points. The experiment was conducted online with 600 UK students (every participant was male, aged 18-25, and was non-vegan and non-vegetarian). While further studies are required, the results suggest that simple low-cost or no-cost labelling and signage interventions may be an effective strategy for increasing more sustainable meal choices. The paper introduces and discusses the terms nudge by proxy, polynudge, environmentalist bias, and scientist bias. The paper makes the case for future experiments that further explore the potential of indirect and multidimensional approaches to non-prohibitive interventions.

behavioural economics, behavioural science, consumer psychology, nudge theory, green nudges, product labels, plant-based, vegan, sustainability, nudge by proxy, polynudge, scientist bias, environmentalist bias