I've been saying this for years: climate science isn't science (in the falsifiable sense), climate is nonlinear and humans don't like to rock the boat. This is especially true with a big, cross-disciplinary project like the IPCC report.

(Yes, I understand parts of climate science are falsifiable... I'm at least semi-educated as a former meteorologist and former PDE guy. But the conclusions of the IPCC report are not testable.)