The ipcc are nothing more than a newspaper, they do not themselves check or monitor the stuff that they publish.
If I had some junior type of science degree I could make any allegations that I want to and publish with them.
It does not signify that I have to know what I am talking about or have knowledge of, as long as I can call myself a scientist and I produce the sort of report that pursues their agenda
So their reports are not of scientific truth but purely peoples opinions, the same as opinions on a variety of subjects, good and bad that we see published daily in the media