I cannot get to the site, but:

At 3C ? Probably and maybe more, but it is hard to know.

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

It's cold, but not that cold.

We need better models.

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.