Despite acknowledged selectivity of data, the role asked of IPCC nations expands with every meeting. Such a role goes far beyond assessment, but is perhaps unavoidable, given the necessity to think that we know what might scientifically be happening as results of human activity. Participants at COP6 are depending on IPCC work. The process appears to divide workers and not seek their collaboration in the end result. Politicians write the policy summaries, not the scientists.
Politicians leave much out of the final reports.
Rarely is underlying work in total agreement. Some chapters may actually disagree with each other and may have reached two different conclusions, but final reports are cleansed to present one supportive position.