century. Since AR5 this has been thought to be very unlikely, but still possible as feedbacks are not well understood. RCP8.5, generally taken as the basis for worst-case climate change scenarios, was based on what proved to be overestimation of projected coal outputs. It is still used for predicting mid-century (and earlier) emissions based on current and stated policies. Projections based on the RCPs 21st century Mid- and late-21st century (2046–2065 and 2081–2100 averages, respectively) projections of global warming and global mean sea level rise from the IPCC Fifth Assessment Report (IPCC AR5 WG1) are tabulated below. The projections are relative to temperatures and sea levels in the late-20th to early-21st centuries (1986–2005 average). Temperature projections can be converted to a reference period of 1850–1900 or 1980–99 by adding 0.61 or 0.11 °C, respectively. Across all RCPs, global mean temperature is projected to rise by 0.3 to 4.8 °C by the late 21st century. According to a 2021 study in which plausible AR5 and SSP scenarios of emissions are selected, Across all RCPs, global mean sea level is projected to rise by 0.26 to 0.82 m by the late-21st century. 23rd century AR5 also projects changes in climate beyond the 21st century. The extended RCP2.6 pathway assumes sustained net negative anthropogenic GHG emissions after the year 2070. "Negative emissions" means that in total, humans absorb more GHGs from the atmosphere than they release. The extended RCP8.5 pathway assumes continued anthropogenic GHG emissions after 2100. In the extended RCP 2.6 pathway, atmospheric CO2 concentrations reach around 360 ppmv by 2300, while in the extended RCP8.5 pathway, CO2 concentrations reach around 2000 ppmv in 2250, which is nearly seven times the pre-industrial level. For the extended RCP2.6 scenario, global warming of 0.0 to 1.2 °C is projected for the late-23rd century (2281–2300 average), relative to 1986–2005. For the extended RCP8.5, global warming of 3.0 to 12.6 °C is projected over the same time period. Up to 2500 In 2021, researchers who found that projecting effects of greenhouse gas emissions only for dates up to 2100 – as widely practiced in research and policy-making – is short-sighted modelled RCP climate change scenarios and their effects for dates up to 2500. See also Coupled Model Intercomparison Project Shared Socioeconomic Pathways References Note: The following references are cited in this article using Template:Harvard citation no brackets: . [Archived . External links Special Issue: The representative