Multi- stage : a rule-based evolution of future commitments under the climate change convention

Résumé En Fr

This article presents the regional emission targets corresponding to different climate regimes for differentiating commitments beyond 2012 on the basis of the Multi-Stage approach. This approach assumes a gradual increase in the number of Parties involved and their level of commitment according to participation and differentiation rules. The analysis focuses on two global greenhouse gas emission profiles resulting in CO2-equivalent concentrations stabilising at 550 and 650 ppmv in 2100 and 2150, respectively. Three Multi-Stage cases have been developed in order to assess different types of thresholds. These share three consecutivestages representing different commitments: stage 1 – no quantitative commitments; stage 2 – emission–limitation targets and stage 3 – emission reduction targets. The analysis shows that by 2025 all three cases result in emission reduction objectives for all Annex I regions of at least 30–55% below their 1990 levels for 550 ppmv, whereas for 650 ppmv target they range from 0 to 20%. Furthermore, early participation is required of the major non-Annex I regions through emission limitation targets i.e. before 2025 and 2050 for the 550 and 650 ppmvtargets, respectively. The first participation threshold for adopting emission–limitation targets on the basis of a capability–responsibility index (as introduced here) can provide for a balanced and timely participation of non-Annex I regions. Major strengths and weaknesses of the climate regimes are discussed and important obstacles and pre-conditions for their feasibilityand acceptability are highlighted.

Cet article présente un mode d'allocation de droits d'émissions de gaz à effet de serre par pays dans le contexte post-2012 (ou post-Kyoto) basé sur le système «Multi-Stage». Ce système considère une participation graduelle de différents pays à des engagements contraignants de réduction de leurs émissions en fonction de critères mixtes de capacité/responsabilité. Deux scénarios d'émissions globales sont étudiés, correspondant à une concentration de gaz à effet de serre de 650 ppmv pour le premier et 550 ppmv pour le second (en équivalent CO2). L'article détaille les résultats analytiques du «Multi-Stage», et le compare avec une allocation des droits d'émissions selon le principe de la convergence des émissions par habitant.