Stabilizing CO₂ concentrations with incomplete international cooperation

Many stabilization scenarios have examined the implications of stabilization on the assumption that all regions and all sectors of all of the world's economies undertake emissions mitigations wherever and whenever it is cheapest to do so. This idealized assumption is just one of many ways in which emissions mitigation actions could play out globally, but not necessarily the most likely. This paper explores the implications of generic policy regimes that lead to stabilization of CO₂ concentrations under conditions in which non-Annex I regions delay emissions reductions and in which carbon prices vary across participating regions. The resulting stabilization scenarios are contrasted with the idealized results. Delays in the date by which non-Annex I regions begin to reduce emissions raise the price of carbon in Annex I regions relative to the price of carbon in Annex I in an idealized regime for any given CO₂ concentration limit. This effect increases the longer the delay in non-Annex I accession, the lower the non-Annex I carbon prices relative to the Annex I prices, and the more stringent the stabilization level. The effect of delay is very pronounced when CO₂ concentrations are stabilized at 450 ppmv, however the effect is much less pronounced at 550 ppmv and above. For long delays in non-Annex I accession, 450 ppmv stabilization levels become infeasible.