Apparently there are probability curves involved in those models also. I think this is a "hand waving" exercise to make themselves sound like they are on top of the situation.
I suspect that this must mean that at each "decision" point in the computer model the dice are rolled using the probability function to decide what will happen.
The lady in purple ( I refuse to find out her name, because I will be biased against anything she writes) discusses the positive feedback loop associated with CO2 causing warming causing increased evaporation causing more greenhouse gas which will warm the earth more causing more warming causing more greenhouse gas...
They can't seem to get it through their heads that their isn't any more energy for the gasses to absorb, which is why this happens.
Unfortunately my degree is not in Climate Science, so my opinion doesn't count.