One of the four scenarios of our future given in the IPCC’s AR5 (2013) is the basis for almost all the disturbing and often apocalyptic forecasts of future climate: RCP8.5. Climate scientists often describe it as the “business as usual scenario”. Scientists, activists, and journalists use horrific forecasts based on RCP8.5 as a core argument for massive public policy action.
Here is an important fact seldom mentioned: RCP8.5 is an unlikely scenario, assuming large changes in long-standing trends of population growth and technology evolution. It cannot be accurately represented as a “business as usual” scenario.
This insight undercuts a large body of the peer-reviewed studies since AR5, and a larger fraction of the scary stories in the general media.
I revised my original post about RCP8.5. You can see the new shorter and clearer version at Climate Etc, the website of eminent climate scientist Judith Curry — where it has sparked a lively discussion (already 125 comments).
Go to Climate Etc and see for yourself.