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Accueil > IMACLIM > Description des modèles IMACLIM > IMACLIM-S


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IMACLIM-static version

Full presentation of the model

IMACLIM-S is a general equilibrium framework designed to assess the macroeconomic impacts of a price- or quantity-based carbon constraint and their sensitivity to the technical abatement costs and to the employed policy tools (tax reforms, trading systems, standards). It allows for describing economies with a) sub-optimal equilibria (unemployment, trade unbalances) b) behaviours of the underlying technical systems that cannot be approximated by well-behaved specifications of production functions for large departures from the reference scenario.

Relying on static analysis, it provides insights that are valid only if it can be assumed that the transition from the reference to the carbon constrained equilibrated pathway is completed and does not imply any transitory disequilibrium that would affect this derived equilibrium .

The main feature of IMACLIM-S is that assumptions regarding both the baseline projection of the energy system and its price-response at the projected time horizon are grounded on information from a bottom-up energy model , with a few ad hoc hypotheses guaranteeing the existence and uniqueness of the derived equilibrium :

- the baseline projection is devised to be price- and quantity-consistent with a bottom-up projection of the energy system, based on shared assumptions regarding main drivers as GDP and population growth.

- the response of the IO coefficients and of consumers to new relative prices is captured through envelopes of the functions generated at t+n by various carbon prices as they result from the bottom-up information ; this comes to use variable point elasticity to capture the bias in technical change induced by the carbon constraint. Notably, the use of envelope functions allows for representing technical asymptotes and technological breakthroughs.

In order to capture the rate and not only the direction of technical progress induced by climate policies IMACLIM-S carries out a comparative static analysis of an endogenous growth mechanism ; investment triggers a Hicks-neutral technical progress affecting factors productivity for the composite good, but total productivity is governed by cumulated experience measured by capital stocks as a proxy. Crowding-out effects of biasing the direction of technical change are computed by withdrawing the investment dedicated to carbon abatement from total investment (under assumption of constant saving ratio) modulo spillover assumptions.

The developed version of IMACLIM-S is calibrated for 14 world regions for three goods (composite, energy, fossil fuels) ; for more in depth scrutiny of issues such as the role of fiscal reforms, competitiveness of exposed carbon intensive industry or the distributive effects, it is preferable to use a version with 9 sectors and two regions (the concerned country or region and the rest of the world can be used.

Different national versions of IMACLIM-S have been developed for France, Brazil, South Africa and are currently under development (China, India, Saoudi Arabia).