“In a high-emissions scenario where little is done to curb planet-heating gases, global mortality rates will be raised by 73 deaths per 100,000 people by the end of the century”
https://www.theguardian.com/us-news/2020/aug/04/rising-globa...
That's an assessment based on what we know, but there's a lot we don't. For instance, it's possible that climate change could lead to a large scale collapse of food chains that could pose an existential risk to humanity.
It's also plausible that climate change will lead to resource shortages that result in wars between nuclear powers, and the nuclear calamity that follows kills us all.