Long-Term Multi-Gas Scenarios to Stabilise Radiative Forcing - Exploring Costs and Benefits Within an Integrated Assessment Framework

Abstract

This paper presents a set of multi-gas mitigation scenarios that aim for stabilisation of greenhouse gas radiative forcing in 2150 at levels from 3.7 to 5.3 W/m2. At the moment, non-CO2 gasses (methane, nitrous oxide, PFCs, HFCs and SF6) contribute to about a quarter of the global emissions. The analysis shows that including these non-CO2 gases in mitigation analysis is crucial in formulating a cost-effective response. For stabilisation at 4.5 W/m2, a multi-gas approach leads to 40% lower costs than an approach that would focus at CO2-only. Within the assumptions used in this study, the non-CO2 gasses contribution to total reduction is very large under less stringent targets (up to 60%), but declines under stringent targets. While stabilising at 3.7 W/m2 obviously leads to larger environmental benefits than the 4.5 W/m2 case (temperature increase in 2100 are 1.9 and 2.3oC, respectively), the costs of the lower target are higher (0.80% and 0.34% of GDP in 2100, respectively). Improving knowledge on how future reduction potential for non-CO2 gasses could develop is shown to be a crucial research question.