IPCC 

Please read up on how the IPCC works. It does not do science itself. What it does is summarize the literature. When you write "Members of the IPCC also concluded" then it shows that you've misunderstood how the IPCC works. Hegerl et al. is Chapter 9 in the AR4 which is a summary of a large number of papers. (and in this case from a large number of models).