Readers have written in to say that it was not the job of the IPCC to provide a self-contained exposition of the scientific issues pertaining to increased CO2. I’ve looked at a couple of statements of the role of the IPCC and there’s certainly nothing that prohibits them from providing a coherent explanation.
IPCC’s website (About) says:
The IPCC was established to provide the decision-makers and others interested in climate change with an objective source of information about climate change. The IPCC does not conduct any research nor does it monitor climate related data or parameters. Its role is to assess on a comprehensive, objective, open and transparent basis the latest scientific, technical and socio-economic literature produced worldwide relevant to the understanding of the risk of human-induced climate change, its observed and projected impacts and options for adaptation and mitigation. IPCC reports should be neutral with respect to policy, although they need to deal objectively with policy relevant scientific, technical and socio economic factors. They should be of high scientific and technical standards, and aim to reflect a range of views, expertise and wide geographical coverage.
One of the differences between the attitude of climate scientists and the public to IPCC is that realclimate scientists put the priority on IPCC as a literature review, while I believe that the public presumes mistakenly that the IPCC carries out independent due diligence, like an engineer or auditor would. Clearly review of recent literature is central to the mandate expressed above.
Now here is another statement of IPCC’s role, which is related to the above, but different.
2. The role of the IPCC is to assess on a comprehensive, objective, open and transparent basis the scientific, technical and socio-economic information relevant to understanding the scientific basis of risk of human-induced climate change, its potential impacts and options for adaptation and mitigation. IPCC reports should be neutral with respect to policy, although they may need to deal objectively with scientific, technical and socio-economic factors relevant to the application of particular policies.
You’ll notice that review of the latest literature does not appear in this statement of role, although the latest literature would obviously be relevant to discharging the assessment of information set out in this statement of role. The second one seems to be the older statement. It would be interesting to know when the phrase about reviewing the latest literature was inserted in the IPCC mandate and whether this phrasing was approved by member governments or merely by the secretariat.