What precisely was settled? Analogy alert!! It is settled science that SARS-CoV-2 is the virus that causes the COVID-19 disease. It is the details that are uncertain, like how long-term Covid occurs or how the virus will mutate in the future.
It is settled science that anthropogenic greenhouse gases are significantly changing the global climate at increasingly faster rates. It is the details that are uncertain, like when the Greenland ice mass will disappear or ocean fisheries collapse.
Seems pretty straightforward. The climate scientists who are doing the heavy lifting on climate change (like the one’s writing the IPCC reports and creating the different climate models) fully understand what RCP8.5 means.
Plus upthread are links demonstrating that the supposedly “extreme” RCP8.5 scenario happens to be the most accurate predictor of global CO2 emissions from 2005 to about 2050. How extreme can RCP8.5 be if it is accurately tracking actual emissions?
So what again are you ranting about?
To put it another way. If you were doing climate research, which RCP scenario would you use? RCP8.5, which has tracked CO2 emissions from 2005-2020 to within 1% of what has been observed, or the remaining RCPs that have underestimated emissions during the same time period?