The impact of climate change and integrated modelling: The share of uncertainty [Impacts du changement climatique et modélisation intégrée, la part de l'arbitraire]

Abstract : To what extent should States curb current and future greenhouse gas emissions? Integrated assessment models are commonly used to build or at least legitimize policy making. Although these models should not be viewed automatically as black boxes, they are particularly complex and are built on restrictive assumptions. Hence results derived from such models need to be taken with caution and on no account as " scientific truth". The aim of this paper is to provide a deeper insight into some of the key methods and assumptions these models are based on. We focused our work on climate change response functions. Assumptions and methods selected to evaluate the influence of climate change impacts will indeed strongly orientate the results derived from integrated assessment models based on cost-benefit concepts. It is therefore essential to point out their chief characteristics and limitations. © NSS-Dialogues, EDP Sciences 2004.