Presentation by Ogutu Keroboto, on Friday the 16th of December about « a simple integrated assessment approach to global change simulation and evaluation ».

Abstract. We formulate and study a simple Coupled Climate–Economy–Biosphere (CoCEB) model. This highly idealized model constitutes the basis of our integrated assessment approach to understanding the various feedbacks involved in the system. CoCEB is composed of a physical climate module, based on Earth’s energy balance, and an economy module that uses endogenous economic growth with physical and human capital accumulation. We concentrate on the interactions between the two subsystems: the effect of climate on the economy, via damage functions, and the effect of the economy on climate, via control of greenhouse gas emissions. Simple functional forms of the relation between the two subsystems permit simple interpretations of the coupled effects. The CoCEB model is used to evaluate hypotheses on the long-term effect of investment in emission abatement, and on the comparative efficacy of different approaches to abatement. In this study, we consider investments in low-carbon technologies as well as carbon capture and storage (CCS) and deforestation reduction. The CoCEB model is highly flexible and transparent; as such, it allows one to easily formulate and compare different functional representations of climate change mitigation policies. Using different mitigation measures and their cost estimates, as found in the literature, one is able to compare these measures in a coherent way. While many studies in the climate–economic literature treat abatement costs merely as an unproductive loss of income, this paper shows that mitigation costs do slow down economic growth over the next few decades, but only up to the mid-21st century or even earlier; growth reduction is compensated later on by having avoided negative impacts of climate change on the economy. Our results also indicate that an increased investment in CCS will not suffice to reduce carbon dioxide (CO2) emissions, and that a reduction of deforestation would be as effective as investment in low- and zero-carbon or CCS technologies for reducing climate damage.