The part you may want starts around footnote 20, in a paragraph that notes 4 degrees as a median projection from the IPCC, with up to 8 degrees at the high end of the curve without factoring in permafrost melt and its associated carbon release or any of a variety of other exacerbating factors (footnoted in the article).
There are ways to calculate how much effort or expense is reasonable to attempt to mitigate a risk, I believe that's often part of the job description of actuaries. Part of it involves figuring out what the cost is if the event in question happens, then what the likelihood of the event is.
The doomsday scenarios may be uncertain, but they do not (to my layman's understand) seem impossible https://en.wikipedia.org/wiki/Clathrate_gun_hypothesis
The IPCC, which is the official authority on climate change, believes that there will be 2-3 degrees C increase in temperature over the next century.
When someone can rationally talk about what will happen in the IPCC predicted scenarios, which is the scientific consensus, then I will listen to them.
If you are some crank, who is talking about 1000 parts per million of C02, and 10 degrees C temp increase by 2100, well then you shouldn't be taken seriously.