Reconciling top-down and bottom-up energy/economy models: a case of TIAM-FR and IMACLIM-R

Recent global economic and environmental forecasts consistently show a trend of continuous decline in natural resources, degradation of environmental quality, increasing vulnerability of economic growth as a result of environmental stress, competition for land and natural resources, soaring energy prices and climate change. These forecasts partly rest on significant efforts by the scientific community over the past three decades to improve knowledge of the interactions between economic growth and the environment; particularly modelling methods have developed to become increasingly applied to the assessment of the environmental and economic consequences of various energy demand and greenhouse gas policies. However, the significantly diverging viewpoints of models developed by energy engineers, or ‘bottom-up’ (BU) models, and those developed by economists, or ‘top-down’ (TD) models, hinder effective dialogue and mutual understanding between researchers from different academic backgrounds. The purpose of this paper is to promote a constructive dialogue between modellers from each side of the modelling paradigms, based on a comparative critique of the BU TIAM-FR model and the TD IMACLIM-R model. The comparison terms extend from the theoretical foundations of each model to their structure and specifications, and applicability to policy assessment. Preliminary numerical simulations are developed to demonstrate the relevance of linking the two models, while the technical challenges and methodological limitations of coupled simulations are addressed.