Climate change: scenarios and integrated modelling

This paper examines the genealogy of long-term studies in economics and its mobilisation in climate change research. Long-term studies differ from short-term forecasting and planning not only in their length of foresight but also by taking account of strategic and policy objectives. These strategic considerations are not within the scope of longue duree historians, nor are they integrated into econometrics or national accounting practices of forecasting. Only planning and prospective analysis include this dimension. The method of scenarios is then at the core of long-term studies and prospective approaches. The conception and use of scenarios is reviewed through various national and international studies since the 1970s - DATAR, OCDE, CPB and, finally, the IPCC scenarios report - as well as their implementation in integrated assessment models (IMAGE, for example).