At 3C ? Probably and maybe more, but it is hard to know. But I think we are headed to 4C with the way things are playing out.

But there is one variable, Nuclear War. I expect that will happen as the climate gets worse and worse. That war could drop us into a cold streak. After that ? Everyone gone ?

This book could give us a kind of a preview into what we are headed for. But in your mind replace nitrogen with CO2

https://www.goodreads.com/book/show/1189676.The_Nitrogen_Fix

The reality is we are on track to break 2C by 2050, and there is nothing that can be done about it. 3C is a real risk later in the century.

Tens to hundreds of millions will be impacted so a realistic range needs to be calculated such that risk mitigation can begin.

I do not like how they have to use circumspect language say the emperor has no clothes...

"The four billion figure is an educated worst-case estimate, not a robust scientific projection."

The only reason "educated" is plausible here is because the people making the silly wild ass guesses have been edumacated; too bad it's not pertinent to the guess.