There is EVERY reason to assume that the models have improved and will improve. The question is, and always has been, how human action has perturbed the biosphere's equilibrium. It is important to know that. We will find that out the same way we've discovered everything else, including how airplanes fly, by conducting research and not by relying on gut feelings and entrenched ideology. Humans did not stop acquiring new knowledge just because some of us got old(er).
On very complex issues there is often the trend, 'the more we know, the more we realize how little we know'.
I find it very bizarre that any scientist could truthfully express certainty about the effects of rising CO2 levels on global warming when even the causes of the previous, most recent change in climate, The Little Ice Age, are not fully understood.
Suggested causes of the previous cooling period include, changing orbital cycles around the sun, low sunspot activity, volcanic eruptions, changes in ocean circulation, decreases in human population in certain areas, increases in human populations in other areas at high altitudes, and/or the inherent variability of climate.
All of those factors might have had a role, including other (so far) unknown factors. Calculating the magnitude and interrelatedness of such factors with any certainty does not yet seem possible, but one fact does seem certain; the current warm period is generally more benign than that bloody awful cold period of The Little Ice Age.
Here's a nice wikipedia article for those who are interested.
https://en.wikipedia.org/wiki/Little_Ice_Age