The Fifth Assessment Report (AR5) did not use the SRES scenarios, but instead introduced the Representative Concentration Pathways (RCPs). The latter represent different greenhouse gas concentration trajectories without explicit linkage to particular global socio-economic pathways (Table 13).

RCP	Meaning
RCP 2.6	A low-emission scenario that assumes significant mitigation efforts, leading to peak radiative forcing at around 2.6 W/m² before declining by 2100.
RCP 4.5	A stabilization scenario where radiative forcing stabilizes at 4.5 W/m² by 2100 without overshooting the target.
RCP 6.0	Another stabilization scenario with radiative forcing stabilizing at 6.0 W/m² by 2100, achieved with some mitigation.
RCP 8.5	A high-emission scenario with no significant mitigation efforts, resulting in radiative forcing reaching 8.5 W/m² by 2100.

RCPs express radiative forcing levels (in watts per square meter) reached by the year 2100 relative to pre-industrial levels. They are a quantitative measure of the influence of greenhouse gases and other factors on the energy balance of the Earth’s atmosphere, and therefore directly outcome-related.

As RCPs directly focus on the impact of emissions on radiative forcing, they facilitate a clearer understanding of the climate response to different socio-economic pathways and provide a more versatile tool for studies on climate change impacts, mitigation and adaptation.

Note:
In publications 112, 115, and 117, we used RCP 8.5 to identify climate change hotspots in Africa. At the time, RCP 8.5 was considered the best representation of cumulative emissions from 2005 to 2020, leading us to conclude that the Earth was on track for a worst-case scenario in terms of greenhouse gas emissions.