Global and Annex I emissions corridors for the 21st century

We analyze global and Annex I emissions corridors for the 21st century. Emissions corridors represent the range of admissible emissions futures which observe some predefined constraints. They are calculated on the conceptual and methodological basis of the tolerable windows approach. We assess the sensitivity of the corridors to limits on the non-intolerable magnitude of climate change, the acceptable rate of emissions reductions and the feasible transition pace towards a decarbonizing economy. In addition we consider the influence of climate sensitivity on the corridors. While we calculate the global emissions corridors for the idealized assumption of a single global emitter, the Annex I emissions corridors are computed for the case of two emitters that have to obtain equal per capita emissions rights as of the year 2050. Results show a large dependence of the corridors on the climate change limit and the climate sensitivity. When the limits are varied within their plausible range, we move from a climate policy regime with vanishing emissions corridors to a regime, where no action seems necessary. The economic parameters have a much larger impact on the the Annex I corridors than on the global emissions corridors. Due to the long term requirement of equal per capita emissions rights, the size of Annex I emissions corridors is strongly influenced by the emissions reductions capabilities of the Annex I countries in the long as well as in the short run.