Definition: Integrated assessment models (IAMs)

Integrated assessment models are used to study both the impacts of climate change as well as adaptation and mitigation pathways (Füssel 2010). IAMs are used as an important tool within a range of scientific fields and disciplines such as climate, environment, and sustainability sciences, and have become increasingly important in policymaking concerning a range of questions (Ellenbeck and Lilliestam 2019). They are extensively relied upon in formulating emission scenarios that serve as a basis for IPCC projections of future climate change, as well as one of the main ways by which the social and economic impacts of future climate change are systematically assessed (van Vuuren et al. 2011).   

Simpler models, such as William Nordhaus’ Dynamic Integrated Climate Economy (DICE) model (see e.g., Nordhaus 2018), are essentially built up from a relatively small number of equations and typically couple macroeconomic models to very rudimentary climate models.