Abstract for: Assessing the impacts of endogenous behavioural change on food demand in a feedback-based global integrated assessment model

Demand-side strategies, including pro-environmental dietary behaviour change, are recog-nized as critical levers for climate mitigation. Yet most assessments rely on exogenous demand trajectories, limiting their ability to capture the complex dynamics of behavioural change. Using the fully coupled feedback-based FRIDAv2.1 model, which endogenizes dietary behaviours, we assess how climate-friendly diet shifts propagate through the food and climate systems. We first conduct a variance-based sensitivity analysis to identify which behavioural pa-rameters most strongly influence dietary outcomes within FRIDA’s endogenous behav-ioural framework. We then design scenario experiments that perturb these high-leverage mechanisms to test conditions under which earlier and more persistent pro-environmental dietary arise and to quantify their mitigation consequences. Sensitivity analysis reveals that socioeconomic accessibility, risk-linked personal norms, and sociocultural valuation parameters dominate dietary outcome variance. Scenario exper-iments show that durable reductions in animal products and total food demand emerge on-ly when multiple levers are activated together; isolated interventions remain vulnerable to stalling and rebound dynamics. Resultant diet shifts substantially reduce agricultural emis-sions but exert limited influence on long-term global temperature and sea-level rise without parallel energy-related reductions. Overall, we demonstrate how endogenizing behavioural change exposes non-linear, path-dependent dynamics that common exogenous assessment frameworks cannot reveal; in turn, providing a more realistic basis for designing and evaluating demand-side climate policy. Our findings highlight both the potential and fragility of diet shifts as a mitigation lever: effective climate policy must prioritize energy behaviour change and decarbonization, while promoting dietary behavioural change as a complement.