The base version of the CLIMNEG world simulation (CWS) model is a multi-region economy–climate derived from the RICE model of Nordhaus and Yang [1996]. Like RICE, the CWS model is an optimal growth model for the world economy, coupled with a basic representation of the carbon cycle and climate system [Nordhaus and Boyer, 1999b]. CWS has been applied in several studies, mainly focusing on the issue of coalition formation in climate policy [Eyckmans and Tulkens, 2003, 2005, Eyckmans and Bertrand, 2000].

The «climatic» part starts from greenhouse gas emissions and computes concentrations and resulting temperatures. As it is a simple model, the key objective when designing and setting the model parameters is to make its main results consistent with current complex models (coupled atmosphere-ocean general circulation models, also called GCMs). We follow the summary work done for the 4th assessement report (AR4, Solomon S. and Manning, 2007) of the IPCC regarding the key parameters that summarize the behaviour of a complex model, such as climate sensitivity.