RCP What?: Predictions of Global Emissions

The IPCC relies heavily on computer models of climate that purport to predict global temperatures in the future. If we assume for a moment that the models are accurate given correct inputs then the main factors that determine future temperatures are future greenhouse gas emissions and emission of other things like aerosols. The IPCC organizes the future into 4 possible scenarios. These are named RCPx where x is the greenhouse gas forcing in W/m[SUP]2[/SUP] that would result by the year 2100. The most extreme scenario is RCP8.5. This is the scenario that is always presented to the public as being the likely outcome if nothing is done about global warming. However, this scenario includes some pretty unlikely assumptions. For one thing it assumes coal consumption will increase drastically when 50% of coal mining in the world is already uneconomical. RCP8.5 assumes that the world would return to a 19th century style of energy production when even China is moving away from coal (I assume it's because they can't breath). Coal consumption has peaked in several nations, both rich and poor, and global consumption of coal fell by 1.2% in 2012. RCP8.5 also assumes that population growth in Africa won't decline even though it has declined everywhere else in the world. It assumes that there will be no technological developments in energy production, that fusion power won't appear, for example.

RCP8.5 isn't the business as usual scenario, it's what would happen if several things went very wrong. Going by the government climate scientists writing for the IPCC and subsequent work done on climate sensitivity, the more likely scenarios are milder.

https://fabiusmaximus.com/2015/07/13/coal-climate-apocalypse-87192/