Multi-gas emission envelopes to meet greenhouse gas concentration targets: Costs versus certainty of limiting temperature increase

Abstract

This paper presents a set of technically feasible multi-gas emission pathways (envelopes) for stabilising greenhouse gas concentration at 450, 550 and 650 ppm CO2-equivalent and their trade-offs between direct abatement costs and probabilities to meet temperature targets. There are different pathways within the envelope. Delayed response pathways initially follow the upper boundary of the emission envelope and reduce more by the end of the century. In contrast, early action pathways first follow the lower boundary and then the upper boundary. The latter require an early peak in the global emissions but keeps the option open for shifting to lower concentration targets in the future. Costs eva..