A conceptual framework for mapping uncertainty in integrated assessment

At a time when Integrated Assessment Modelling is increasingly providing the scientific basis for policy development in relation to air quality and climate change, scientists and modellers are facing a dilemma: How can we effectively address uncertainty? Whereas policy makers demand quantifications of uncertainty from these state-of-the-art models, the increasingly complex and inter-dependent scientific domains and spheres of human activity captured by the models means that scientists can rarely provide better than qualitative representations of uncertainty. Using the context of the UK Integrated Assessment Model we present a conceptual framework within which uncertainties in different components of integrated assessment models can be classified. We show how an hierarchy of uncertainties can be identified which will assist policy makers in understanding where an uncertainty arises and to what extent it may impact upon policy development. Policy makers must still make the decisions. This generic conceptual framework will help scientists and modellers to provide policy makers with an understanding of uncertainties involved whilst highlighting that models are only heuristic tools designed to help make the decision and understand the potential impacts of that decision in an inherently uncertain world.