RCP 8.5—A scenario of comparatively high greenhouse gas emissions

TLDR

RCP8.5 assumes high population growth, slow income growth, modest technological change, and energy‑intensity improvements, resulting in the highest long‑term greenhouse‑gas emissions among Representative Concentration Pathways. This paper summarizes the main characteristics of the RCP8.5 scenario. Using the IIASA Integrated Assessment Framework and the MESSAGE model, the authors extend RCP8.5 with spatially explicit air‑pollution projections, enhanced land‑use and land‑cover change projections, and scenario variants that incorporate different mitigation policy levels. The modeling shows it is technically feasible to reduce RCP8.5 forcing to levels comparable to other RCPs (2.6–6 W/m²) and that climate‑policy‑driven changes in global energy supply and demand can yield significant co‑benefits for local air pollution.

Abstract

This paper summarizes the main characteristics of the RCP8.5 scenario. The RCP8.5 combines assumptions about high population and relatively slow income growth with modest rates of technological change and energy intensity improvements, leading in the long term to high energy demand and GHG emissions in absence of climate change policies. Compared to the total set of Representative Concentration Pathways (RCPs), RCP8.5 thus corresponds to the pathway with the highest greenhouse gas emissions. Using the IIASA Integrated Assessment Framework and the MESSAGE model for the development of the RCP8.5, we focus in this paper on two important extensions compared to earlier scenarios: 1) the development of spatially explicit air pollution projections, and 2) enhancements in the land-use and land-cover change projections. In addition, we explore scenario variants that use RCP8.5 as a baseline, and assume different degrees of greenhouse gas mitigation policies to reduce radiative forcing. Based on our modeling framework, we find it technically possible to limit forcing from RCP8.5 to lower levels comparable to the other RCPs (2.6 to 6 W/m2). Our scenario analysis further indicates that climate policy-induced changes of global energy supply and demand may lead to significant co-benefits for other policy priorities, such as local air pollution.