For sure, but they may also use simple projection or just current levels already, as negative feedbacks are already accounted for. These will start breaking from 2030 however, so we might see further acceleration until equalization is reached.

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.