emphasises the fact that not only the long-term concentration levels, but also the trajectory taken over time to reach that outcome are of interest . RCPS usually refer to the portion of the concentration pathway extending up to 2100, for which integrated assessment models produced corresponding emission scenarios. Extended concentration pathways describe extensions of the RCPs from 2100 to 2300 that were calculated using simple rules generated by stakeholder consultations, and do not represent fully consistent scenarios. Four RCPs produced from integrated assessment models were selected from the published literature and are used in the Fifth IPCC Assessment and are also used in this Assessment for comparison, spanning the range from approximately below 2°C warming to high  warming best-estimates by the end of the 21st century: A RCP2.6, RCP4.5 and RCP6.0, and RCP8.5.
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report