I would have expected organizations such as the Sierra Club, The WWF, Greenpeace, and the Union of Concerned Scientists to be mentioned among this group, but The IPCC should not if it is to have any credibility.
It’s interesting that the IPCC reports mix scientific literature with the more questionable gray literature from some of these organizations. Some of that same gray literature has been the source of disputes and outright erroneous claims. I have to wonder how much this mixture contributes to the perception of some that criticism of the IPCC as an “attack on science”.