U.N. climate panel confronts implausibly hot forecasts of future warming
sciencemag.org
sciencemag.org
Not sure how, when there are zero credible plans for cutting emissions (they are accellerating), or sequester 40+ Gigaton CO2 per year. Nothing so far addresses extra releases from burning biomass, acidification of oceans and declining albedo.
Any serious measure can use uncertainty and other measures in combination.
Economy tends to undershoot existential risks, so think bailouts until the supply-lines break down. We already saw the world flirting with this just from the Corona-situation.
Mitigations tend to be reactive, rather than proactive, and may overshoot for individual random events compared to overall preparedness.
Such complex models will come with flaws. The concern is however that scientists find few significant redeeming factors overall. The concern is that the older models are too conservative even.
Complete collapse of the current civilization and population drops of 90% or even 99% aren't impossible. But there's an enormous difference between a 99% loss and a 100% loss.