Optimization of CO_2 emissions using coupled integral climate response and simplified cost models. A sensitivity study

A cost-benefit analysis for greenhouse warming based on a structurally simplified globally integrated coupled climate-economic costs model SIAM (Structural Integrated Assesment Model) is used to compute optimal paths of global CO_2 emissions which minimize the net sum of climate damage and mitigation costs. The climate model is represented by a linearized inpulse-response model calibrated against a coupled ocean-atmosphere general circulation climate model and a three-dimensional global carbon-cycle model. The cost terms are represented by strongly simplified expressions designed for the study of the sensitivity of the computed optimal emission paths with respect to critical input assumptions. These include the discount rates assumed for mitigation and damage costs, the inertia of the socio-economic system, and the dependence of climate damages on the change in temperature and the rate of change of temperature. Different assumptions regarding these parameters are believed to be the origin of the marked divergences of existing cost-benefit analyses based on more sophisticated economic models. The long memory of the climate system implies that very long time horizons of several hundred years are needed to optimize CO_2 emissions on time scales relevant for a policy of sustainable development. Cost-benefit analyses over shorter time scales of a century or two can lead to dangerous underestimates of the long term climatic impact of increasing greenhouse-gas emissions38 refs.Available from TIB Hannover: RR 1347(192) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman