Summary

Decision makers ’ growing call for advice on strategies and actions to mitigate climate change and energy security threats creates a twin new challenge for economy-energy-environment modellers. First, the focus on short-term mitigation strategies requires the integration of expert judgment on short term trends within longer-term scenarios; second, the modelling framework should be constructed so as to facilitate interaction with both decision makers and a large variety of sectoral and technology experts. WEM-ECO is a hybrid model coupling the bottom-up technology-rich IEA WEM model with the top-down general equilibrium model IMACLIM-R. The iterative coupling procedure can be implemented at different levels depending on the time horizon considered and the uncertainty about technological and economic parameters. The WEM-ECO modular framework serves as a bridge and analytical framework for discussion between different communities of experts, while ensuring the internal consistency of the IEA energy-economy scenarios. The paper describes how the model architecture was specifically designed to facilitate the incorporation of expert judgment and facilitate convergence towards a common set of internally consistent scenarios. The lessons drawn from the interaction process between the various experts and the central role played by the model as an integrator of different visions within a consistent view of the future are discussed