Read here and here. As most sentient beings have finally come to realize over the past twelve months, the IPCC is a political organization, with a political agenda, using non-scientific means to mislead, misinform and misrepresent. Or, to put it in more colorful terms, the United Nation's IPCC is a non-repentant agency of climate science bullshit, and any "scientific" claim emanating from this agency should be intently scrutinized and parsed to determine its veracity and objectivity (lack thereof).
The latest evidence that the IPCC is guilty of non-scientific, political propaganda at the minimum, with the IPCC potentially being an accessory to science incompetence (malfeasance?)? One word answer: Amazongate.
1. [Dr. Roger Pielke, Jr] "The bottom line here? The IPCC did indeed make a claim in its report that is unsubstantiated in the literature that it cited in support of the claim. Further, the specific claim being made also appears to be unsubstantiable -- that is, there is nothing in the literature to support the specific claims being made.....For the IPCC this degree of sloppiness and lack of attention to accuracy is troubling. Those claiming that there is nothing to see here are simply wrong -- the IPCC botched this one. The various defenses of this issue are an embarrassment.....Pretending that it did not cannot help either the IPCC or the cause for action, and will likely have the opposite effect, as anyone who takes a moment to look at the issue, as I did, will see the same evidence that I did."
2. [Nasa funded peer-reviewed study] "A new study, funded by Nasa, has found that the most serious drought in the Amazon for more than a century had little impact on the rainforest's vegetation. The findings appear to disprove claims by the Intergovernmental Panel on Climate Change (IPCC) that up to 40% of the Amazon rainforest could react drastically to even a small reduction in rainfall and could see the trees replaced by tropical grassland. The IPCC has already faced intense criticism for using a report by environmental lobby group WWF as the basis for its claim, which in turn had failed to cite the original source of the research. Scientists have now spoken out against the 40% figure contained in the IPCC report and say that recent research is suggesting that the rainforest may be more resilient to climate change than had been previously thought.....senior researcher in the new study, criticised the IPCC’s claim that a “even a slight reduction in precipitation” would cause drastic changes in the rainforest.....He said: “There was more than a slight reduction in precipitation during the drought of 2005. It is that particular claim of the IPCC that our analysis rejects.”"
The UN's IPCC has become a global climate science joke that is definitely controlled and managed by political, ideological hacks. The harm to science credibility that the IPCC has perpetrated is immeasurable and will continue for the foreseeable future. In terms of objective, honest climate science, the IPCC is not to be trusted, ever.