Carrot, stick, or both? Price incentives for sustainable food choice in competitive environments

2025-12-15

AI Summary

Meat consumption is a major contributor to global agricultural carbon emissions, yet existing price-intervention studies are largely confined to simplified experimental settings. This study conducts a large-scale, sequential crossover field experiment in real-world, competitive university dining environments in Switzerland to systematically evaluate the impact of three pricing interventions—vegetarian discounts, meat surcharges, and their combination—on meal choices and associated carbon footprints. Its key contribution lies in being the first to empirically validate hybrid pricing mechanisms in an open, multi-option, real-world context. Results show that both the meat surcharge alone and the combined intervention significantly increase vegetarian selection rates (the combination yields a +16.6% increase), reduce per-meal carbon emissions by 11.3%, and incur no loss in sales or revenue. Both interventions prove effective among habitual meat-eaters; notably, the combined strategy mitigates spillover effects that otherwise offset environmental gains.

Technology Category

• Game Theory and Economic Paradigms: Social Choice / Voting
• Multiagent Systems: Mechanism Design
• Search and Optimization: Mixed Discrete/Continuous Search

Application Category

• Economics, Online Markets and Human Computation: The sharing economy
• Security and Privacy: Large-scale security measurements
• User Modeling, Personalization and Recommendation: Accountability, Transparency, and Ethics for personalization

Abstract

Meat consumption is a major driver of global greenhouse gas emissions. While pricing interventions have shown potential to reduce meat intake, previous studies have focused on highly constrained environments with limited consumer choice. Here, we present the first large-scale field experiment to evaluate multiple pricing interventions in a real-world, competitive setting. Using a sequential crossover design with matched menus in a Swiss university campus, we systematically compared vegetarian-meal discounts (-2.5 CHF), meat surcharges (+2.5 CHF), and a combined scheme (-1.2 CHF=+1.2 CHF) across four campus cafeterias. Only the surcharge and combined interventions led to significant increases in vegetarian meal uptake--by 26.4% and 16.6%, respectively--and reduced CO2 emissions per meal by 7.4% and 11.3%, respectively. The surcharge, while effective, triggered a 12.3% drop in sales at intervention sites and a corresponding 14.9% increase in non-treated locations, hence causing a spillover effect that completely offset environmental gains. In contrast, the combined approach achieved meaningful emission reductions without significant effects on overall sales or revenue, making it both effective and economically viable. Notably, pricing interventions were equally effective for both vegetarian-leaning customers and habitual meat-eaters, stimulating change even within entrenched dietary habits. Our results show that balanced pricing strategies can reduce the carbon footprint of realistic food environments, but require coordinated implementation to maximize climate benefits and avoid unintended spillover effects.

Problem

• Evaluating price interventions for sustainable food choices in competitive settings
• Assessing meat surcharges and vegetarian discounts on meal selection and emissions
• Measuring spillover effects and economic viability of combined pricing strategies

Innovation

• Combined vegetarian discount and meat surcharge pricing strategy
• Real-world field experiment in competitive campus cafeterias
• Balanced pricing reduces emissions without harming sales