If CO2 and methane double (which we are closing in on) that locks in 1.0 to 1.2 degrees Celsius or 1.8 to 2.2 degrees Fahrenheit of warming. 100% settled, but note the range of uncertainty. This depends on all of the previous pieces.
My recollection from IPCC AR5 is that this particular bit isn’t settled. The other stuff is settled, but this one isn’t.
I think the range in AR5 is much wider, and different than previous AR issues, and the variance in the modeling is so wide they don’t even issue an expected value as in previous editions. If I recall correctly, the lower bound is more like 0.6, and the higher bound is up around 7. Correct me if I’m wrong. I can’t find my copy of AR5 right now. And that’s the number we need to be able to craft policy.
My other main gripe with AR5 is they seem to be diminishing other warming effects without looking as deeply into them as they need to. Land use and cloud cover were biggies, related to albedo. It’s been a while since I read it, but if I recall, AR5 seemed to state that deforesting half the world’s forests, as we’ve done in the last 100 years, combined with all our urbanization which causes heat you can literally see from space, had a net cooling effect on the planet. That doesn’t pass the sniff test, for me anyway.
I’m not against climate science. I think we need a lot more of it.