International audienceTo assess the sustainability of future development pathways requires models to compute long-run Economy-Energy-Environment scenarios. This paper presents the IMACLIM-R framework, aimed at investigating climate, energy and development inter-related issues. The model was built in an attempt to address three methodological challenges: to incoporate knowledge from economics and engineering sciences, to support the dialogue with and between stakeholders, to produce scenarios with a strong consistency, concerning especially the interplay between development patterns, technology and growth. These goals led to the development of a recursive structure articulating a static general equilibrium framework including innovative features and sectorspecific dynamic modules now concerning energy, transportation and industry. This paper provides the general rationale of the model and the description of all its components

This paper envisages endogenous technical change that results from the interplay between the economic growth engine, consumption, technology and localization patterns. We perform numerical simulations with the recursive dynamic general equilibrium model Imaclim-R to study how modeling induced technical change affects costs of CO 2 stabilization. Imaclim-R incorporates innovative specifications about final consumption of transportation and energy to represent critical stylized facts such as rebound effects and demand induction by infrastructures and equipments. Doing so brings to light how induced technical change may not only lower stabilization costs thanks to pure technological progress, but also trigger induction of final demand-effects critical to both the level of the carbon tax and the costs of policy given a specific stabilization target. Finally, we study the sensitivity of total stabilization costs to various parameters including both technical assumptions as accelerated turnover of equipments and non-energy choices as alternative infrastructure policies.

Abstract.Interactions between food demand, biomass energy and forest preservation are driving both food prices and land-use changes, regionally and globally. This study presents a new model called Nexus Land-Use version 1.0 which describes these interactions through a generic representation of agricultural intensification mechanisms within agricultural lands. The Nexus Land-Use model equations combine biophysics and economics into a single coherent framework to calculate crop yields, food prices, and resulting pasture and cropland areas within 12 regions inter-connected with each other by international trade. The representation of cropland and livestock production systems in each region relies on three components: (i) a biomass production function derived from the crop yield response function to inputs such as industrial fertilisers; (ii) a detailed representation of the livestock production system subdivided into an intensive and an extensive component, and (iii) a spatially explicit distribution of potential (maximal) crop yields prescribed from the Lund-Postdam-Jena global vegetation model for managed Land (LPJmL). The economic principles governing decisions about land-use and intensification are adapted from the Ricardian rent theory, assuming cost minimisation for farmers. In contrast to the other land-use models linking economy and biophysics, crops are aggregated as a representative product in calories and intensification for the representative crop is a non-linear function of chemical inputs. The model equations and parameter values are first described in details. Then, idealised scenarios exploring the impact of forest preservation policies or rising energy price on agricultural intensification are described, and their impacts on pasture and cropland areas are investigated.

This article explores the critical role of labour market imperfections in climate stabilization cost formation, using a dynamic recursive energy-economy model that represents a second-best world with market imperfections and short-run adjustment constraints along a long-term growth path. The degree of rigidity of the labour markets is a central parameter, and a systematic sensitivity analysis of the model results confirms this. When labour markets are represented as highly flexible, the model results are in the usual range of the existing literature; that is, less than 2% GDP losses in 2030 for a stabilization target at 550 ppm CO 2 equivalent. However, when labour market rigidities are accounted for, mitigation costs increase dramatically. Accompanying measures are identified, namely labour subsidies, which guarantee against the risk of large stabilization costs in the case of high rigidities of the labour markets. This complements the usual view that mitigation is a long-term matter that depends on technology, innovation, investment and behavioural change. The results support the view that mitigation is also a shorter-term issue and a matter of transition with regard to the labour market.Keywords: climate policy costs; labour market rigidities; second-best world; sensitivity analysis Le rôle déterminant des imperfections du marché du travail dans la formation des coûts de l'atténuation du changement climatique est exploré, avec un modèle de l'interface énergie-économie, récursif et dynamique, qui représente un monde de second rang avec des imperfections du marché du travail et des contraintes d'ajustement de court terme le long d'une trajectoire de croissance à long terme. Le degré de rigidité des marchés du travail est un paramètre central, ceci étant confirmé par une analyse de sensibilité systématique des résultats. Lorsque les marchés du travail sont représentés comme très flexibles, les résultats se situent dans la fourchette habituelle de la littérature existante (c'est-à-dire moins de 2% de pertes de PIB mondial en 2030 pour une cible de stabilisation à 550 ppm équivalent CO 2 ). Cependant, lorsque les rigidités du marché du travail sont prises en compte, le coût de l'atténuation augmente très significativement. Des mesures d'accompagnement, à savoir des subventions sur le travail, garantissent contre le risque de coûts de la stabilisation élevés dans le cas de fortes rigidités sur le marché du travail. Cette vision complète la conception habituelle selon laquelle l'atténuation est une question de long terme qui dépend de la technologie, de l'innovation, de l'investissement et des changements de comportements. L'article signale que l'atténuation est aussi un problème de plus court terme et une question de transition sur les marchés du travail.Mots clés : analyse de sensibilité; coût des politiques climatiques; monde de second rang; rigidités des marchés du travail

Interactions between food demand, biomass energy and forest preservation are driving both food prices and land-use changes, regionally and globally. This study presents a new model called Nexus Land-Use version 1.0 which describes these interactions through a generic representation of agricultural intensification mechanisms. The Nexus Land-Use model equations combine biophysics and economics into a single coherent framework to calculate crop yields, food prices, and resulting pasture and cropland areas within 12 regions inter-connected with each other by international trade. The representation of cropland and livestock production systems in each region relies on three components: (i) a biomass production function derived from the crop yield response function to inputs such as industrial fertilisers; (ii) a detailed representation of the livestock production system subdivided into an intensive and an extensive component, and (iii) a spatially explicit distribution of potential (maximal) crop yields prescribed from the Lund-Postdam-Jena global vegetation model for managed Land (LPJmL). The economic principles governing decisions about land-use and intensification are adapted from the Ricardian rent theory, assuming cost minimisation for farmers. The land-use modelling approach described in this paper entails several advantages. Firstly, it makes it possible to explore interactions among different types of biomass demand for food and animal feed, in a consistent approach, including indirect effects on land-use change resulting from international trade. Secondly, yield variations induced by the possible expansion of croplands on less suitable marginal lands are modelled by using regional land area distributions of potential yields, and a calculated boundary between intensive and extensive production. The model equations and parameter values are first described in details. Then, idealised scenarios exploring the impact of forest preservation policies or rising energy price on agricultural intensification are described, and their impacts on pasture and cropland areas are investigated