The fact is, for all of these other secondary effects etc... we just don't know. It's too complicated of a system.
So as a result, we've got a prediction of something between "somewhat bad" and "catastrophically-is-an-understatement bad" with a maximum likelihood estimate of "really really bad."
No. I believe what you're saying is very likely to be true, but we know there's both positive and negative feedback and we don't really know how they really will interplay and where all the tipping points are.
There may even be significant phase delay in these mechanisms and so we could even get oscillation.
Edit: I'd be happy for you to educate me how I'm wrong btw, since that would mean I've missed something significant, which would make me happy! So please do tell me if you know of such a mechanism.
There are all kinds of things that have time lags from years to centuries, though, that could cause ringing (ocean heat uptake, rates of carbon uptake as the biosphere adapts and shifts, etc).
Indeed, we have evidence of ringing in the geologic climate record-- like Dansgaard-Oeschger events. We also live with ringing in weather systems like El Nino. Warming intensifying or creating new modes of oscillation would not be that surprising.
I wish this comment was higher up.
The big thing under-discussed about climate change is that the deeper we get into it, the harder it is to predict and understand.
I recall Dr. Richard Alley discussing how Thwaites Glacier collapsing wasn't factored into any IPCC reports; but ultimately pointed out it was for good reason because it's simply not possible to model these things and their consequences accurately.
I don't do any climate modeling, but I do a lot of other modeling and forecasting: the biggest assumption we make in all statistical models is that the system itself more or less stays statistically similar to what it currently is and what we have seen in past. As soon as you drop that assumption you're increasingly in the world of wild guessing. If you wanted me to build you a RAM price prediction model 2 years ago, I could have done a pretty good job. Ask for one today and your better off asking someone with industry but no modeling experience what they think might happen.
This is the hidden threat of climate change most people are completely unaware of: we can know it will be bad when certain things happen, we know they will happen in the nearish future, but we can't really say exactly how and when they'll unfold with any meaningful confidence.