This paper summarizes the key characteristics of the RCP8.5 scenario, which represents a high greenhouse gas emissions pathway. RCP8.5 combines assumptions about high population growth, slow income growth, modest technological change, and energy intensity improvements, leading to high energy demand and GHG emissions without climate change policies. Compared to other Representative Concentration Pathways (RCPs), RCP8.5 is the scenario with the highest greenhouse gas emissions. The paper focuses on two main extensions: spatially explicit air pollution projections and enhanced land-use and land-cover change projections. It also explores scenario variants using RCP8.5 as a baseline and different levels of greenhouse gas mitigation policies to reduce radiative forcing. The modeling framework, including the IIASA Integrated Assessment Framework and the MESSAGE model, is described, and the results of RCP8.5 and mitigation scenarios are presented. The analysis indicates that it is technically possible to limit forcing from RCP8.5 to levels comparable to other RCPs (2.6 to 6 W/m²). Additionally, climate policy-induced changes in global energy supply and demand may lead to significant co-benefits for local air pollution control.This paper summarizes the key characteristics of the RCP8.5 scenario, which represents a high greenhouse gas emissions pathway. RCP8.5 combines assumptions about high population growth, slow income growth, modest technological change, and energy intensity improvements, leading to high energy demand and GHG emissions without climate change policies. Compared to other Representative Concentration Pathways (RCPs), RCP8.5 is the scenario with the highest greenhouse gas emissions. The paper focuses on two main extensions: spatially explicit air pollution projections and enhanced land-use and land-cover change projections. It also explores scenario variants using RCP8.5 as a baseline and different levels of greenhouse gas mitigation policies to reduce radiative forcing. The modeling framework, including the IIASA Integrated Assessment Framework and the MESSAGE model, is described, and the results of RCP8.5 and mitigation scenarios are presented. The analysis indicates that it is technically possible to limit forcing from RCP8.5 to levels comparable to other RCPs (2.6 to 6 W/m²). Additionally, climate policy-induced changes in global energy supply and demand may lead to significant co-benefits for local air pollution control.