Abstract for: A system dynamics modeling framework for endogenizing human behavior change in global-scale integrated assessment models

Integrated Assessment Models have come to occupy a pivotal role in evaluating the multifaceted and complex interactions of the human-climate systems for informing climate change mitigation and adaptation policies. However, current models often lack explicit representations of human behavior and social systems necessary for assessing demand-side policies. In this paper, we introduce and provide a detailed description of our modeling framework for endogenizing human behavior change in the global-scale FRIDA model, specifically focusing on behavioral processes related to environmentally significant diet choices. The framework models human behavior as a function of three sources of motivations (perceived accessibility, descriptive norms, and personal norms), constrained by accessibility and past behavior. Consistent with literature, our results show that endogenizing behavior change leads to lower baseline climate projections. However, we found that a pro-environmental behavioral response, indicated by both a reduction of consumption and substitution of animal products, may not be an enduring phenomenon: behavior change could reverse in the future from weakening threat perceptions over time. Our work contributes to the limited work on human behavior in climate models, extending current representations to include more dynamic complexity. It also contributes to the system dynamics field for modeling social norms and risk perceptions.