This paper is based on the perception that the inertia of climate and socio-economic systems are key parameters in the climate change issue. In a ﬁrst part, it develops and implements a new approach based on a simple integrated model with a particular focus on an innovative transient impact and adaptation modeling. In a second part, a climate-economy feedback is deﬁned and characterized. It is found that : (i) it has a long characteristic time, which lies between 50 and 100 years depending on the hypotheses. This time-scale is long when compared to the system’s other time-scales, and the feedback cannot act as a natural damping process of climate change ; (ii) mitigation has to be anticipated since the feedback of an emission reduction on the economy can be signiﬁcant only after a 20-year delay and is really eﬃcient only after at least 50 years ; (iii) even discounted, production changes due to an action on emissions are signiﬁcant over more than one century ; (iv) the IPCC methodology, that neglects the feedback from impacts to emissions, is acceptable up to 2100, whatever is the level of impacts. This analysis allows also to deﬁne a climatic cost of growth as the additional climate change damages due to the additional emissions linked to economic growth.
Keywords : Climate change, impacts, economic growth, feedback analysis