Andrew Dessler, Professor of Atmospheric Sciences at Texas A&M University, uploaded a good short video where he talks about how likely it would be that climate sensitivity is less than 2 degrees. It puts some of the more recent papers into context as to why they might be underestimating climate sensitivity:
My only nitpick about this video is that he didn’t mention that if you look at how our planet has reacted in the distant past a low climate sensitivity isn’t supported. If you do a review of these studies it shows that the climate sensitivity of our planet is somewhere between 2 and 4.5 degrees (with a few big jumps upwards, but those are the exception).
This alone is a very strong indicator that these recent sensitivity studies underestimate climate sensitivity. Like Dessler said this could be because not all the forcings are reckoned for. Although another big contributor to this could be that the climate is very noisy in the short-term. This last one is something that has been brought up a few times in the context of these studies.
Gauging the climate sensitivity of our planet is not easy, but so far there isn’t a solid case that this has been grossly overestimated.