Jack Wright: “Judgment and Constraints: The Use of Climate Mitigation Models in Decision Making”

Abstract

Computational models are now key decision aids in government, the legal system, and the private sector. But not all models are equal.

In the face of the climate change, policy makers must decide what to do. Enter a set of large and influential climate mitigation models: Integrated Assessment Models (IAMs), which promise detailed quantitative analysis of different potential policy pathways. But in contrast to climate models and weather models, the role of accepted knowledge and observational feedback in IAMs is much more limited. I will argue that IAMs should therefore not be seen as primarily empirically determined, but as tools that structured expert judgements.

IAMs are not the only models that have been developed to meet the demand of science-based analysis to support urgent action in a domain where our knowledge is limited. Moreover, very few will deny that modeler judgment is an essential and unavoidable part of modelling. But how much room there is for judgment, contra how much the outputs are constrained by other factors, differs. And this makes a difference. It is important to recognise the degree of space for modeller judgment in such models, as this has implications for their role in collective decision making.