This paper aims at exploring the implications of various international climate regimes for differentiating future commitments compatible with Article 2 of the Climate Change Convention, i.e., stabilising the greenhouse gas concentration at a ‘non-dangerous’ level. Three climate regimes explored are: (1) the Multi-stage approach, with a gradual increase in the number of Parties involved and their level of commitment according to participation and differentiation rules; (2) the Convergence approach, with universal participation and a convergence of per capita emissions and (3) the Triptych sector and technology-oriented approach, with universal participation in which the emission allowances are determined by applying differentiation rules according to sector, e.g., convergence of per capita emissions in the domestic sector, and efficiency and de-carbonisation targets in the energy-intensive industrial and power-producing sectors. The FAIR (Framework to Assess International Regimes for the differentiation of commitments) model is used to explore the implications of these regimes for future emission allowances. It was not the objective to reach any conclusions about what type of regime would be preferred. Analysis of the three approaches shows that substantive reductions of Annex I emissions will be needed for stabilising CO2 concentration at 450 ppmv by 2100, as well as timely participation of the non-Annex I regions in global emissions control.
