Valuing Diverse Climate Impacts in Integrated Assessment Models


Some studies on the impacts of climate change use a “damage” function that assigns a dollar value to the physical effects of climate change. U.S. Department of Energy researchers at the Massachusetts Institute of Technology’s (MIT) Joint Program on the Science and Policy of Global Change believe that this approach is limited because of the large uncertainty surrounding climate change. The MIT Integrated Global Systems Model (IGSM), described in a special edition of Climate Change, integrates the Earth system with an economic model that allows researchers to describe human activities that contribute to environmental change or are affected by it. The MIT approach also provides an opportunity to understand the complex dynamics of the system’s interactions. For example, the possible effects of tropospheric ozone on crop productivity and yields can be explored individually as part of a process representation rather than a blended, generalized economic assumption. One challenge is the ability to describe specific physical relationships in the Earth system that are not known because the climate system has not yet experienced those changes (e.g., connecting climate change to outbreaks of pests). In the IGSM, the researchers confront this and other challenges by focusing on physical impacts that can be described and quantified and by conducting uncertainty analyses to better understand the full range of potential future effects. This mixed approach of valuing impacts, evaluating physical and biological effects, and working to better describe uncertainties in the Earth system can contribute to understanding the options and implications for various mitigation and adaptation strategies.


Reilly, J., et al. 2012. “Valuing Climate Impacts in Integrated Assessment Models: The MIT IGSM,” Climatic Change, DOI: 10.1007/s 10584-012-0635-x.