Being pedantic, the IPCC produces summaries and digests. It does not represent nature and isn't a proper study of scientific research. The ephemeral folks (at least here in the US they serve only temporarily and should be active researchers in their own right) in the meeting room considering research grant proposals would probably find some research proposal that was nothing other than a directed attack at the IPCC as entirely political and certainly not scientific. I'm having a hard time thinking of how such a proposal could be framed as science.
More, it's hard to suggest some kind of research proposal where the outcome is "already known," as Rich's inane suggestion would have it. Research is, almost by definition, an "examining and finding out." Somehow it boggles my mind to imagine a conclusion as a proposal for research. Why should it be funded?
On the other hand, a research grant proposal that specified some independent approach to address an older question in a new way might find funding support by the investigator when it was re-presented to the teams later on. Or one that picks up upon some of the assumptions applied in tentative conclusions formed from earlier research and attempts to test them through an approach that appears workable. Novel ideas do get attention, particularly if the approach seems well reasoned.
Everything is done in bits and pieces, with "an aim to establish general rules determining reciprocal connections of objects and events in time and space." It's frankly not about the IPCC, which is not nature but more about summarizing what present knowledge says about global climate. As you've repeatedly pointed out, they just summarize. I can't see the IPCC itself as a valid target of research.
Jon