There's a certain group of people that take the absolute worst predictions of climate science and just runs with it. Granted, there's a far larger group of people that think we'll be ok with business as usual. Neither is true.
I'm using BAU loosely here. I'm not referring to RCP 8.5. I have my own issues with the IPCC's estimates relying to much on direct air capture, but I don't think 5-6c is likely unless there's an unforseen feedback loop we haven't factored in.
I'd almost bet money on the eventual use of stratospheric sulfide injection to cool the planet. It's cheap enough that even a third world country could conceivably pay for it. We have no idea what the side effects will be, but it may well be worth the risk to avoid 3-4c of warming.
