The IPCC only claims that to be 95-100%.
Literally the only thing the IPCC is virtually certain of is that the upper oceans warmed since 1970.
If you are pointing at studies that haven't been incorporated by the IPCC, then they are definitely subject to doubt. This isn't some deterministic problem you can repeat in a lab and science the shit out of. This is heuristics, fudges, and elbow grease type science where we do our best and then compare against the same type of work of others.
Yes. Though that sounds like weasel words, the word change is missing.
It was 100% proven that human contribution is the main and most important culprit of (the current) climate change. Also that human released CO2 is the most important mechanism.