According to this interesting post by Ira Glickstein at WUWT, climate sensitivity is multi-modal. My take on Glickstein's excellent post is is that the sensitivity is either multi-modal, in which case there is no global sensitivity to CO2, or the sensitivity is so uncertain that we don't know what's going on anyway. In other words, the idea of climate sensitivity is blown out of the water and so are computer models using it - ie all of them.
The post is very clearly written, very easy to understand and well worth a read even if you aren't too comfortable with the technical stuff. As one guy (mpaul) says in the comments:-
"The average human has one testicle and one ovary."