Here is a discussion on the mission of the IPCC that I copied from the blog "Classical Values"

The IPCC Mandateby Simon
What is the Intergovernmental Panel on Climate Change (IPCC) statement of purpose? Is the organization supposed to find the cause of global climate change and report on what can be done? Why no.
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.Hmmm. They already have their minds made up. Only human induced climate change is of interest to them.
So how do they go about their job? Do they do science? Why no.
The IPCC does not carry out research nor does it monitor climate related data or other relevant parameters. It bases its assessment mainly on peer reviewed and published scientific/technical literature.OK so they pick the papers that go into their various reports. And the reports are mainly backed by peer reviewed science. Mainly. I wonder what is the minor component. Doesn't say. Voodoo? Phase of the moon? Politics? I have my suspicions.
Richard Lindzen has his suspicions as well.
So how is it that we don't have more scientists speaking up about this junk science? It's my belief that many scientists have been cowed not merely by money but by fear. An example: Earlier this year, Texas Rep. Joe Barton issued letters to paleoclimatologist Michael Mann and some of his co-authors seeking the details behind a taxpayer-funded analysis that claimed the 1990s were likely the warmest decade and 1998 the warmest year in the last millennium. Mr. Barton's concern was based on the fact that the IPCC had singled out Mr. Mann's work as a means to encourage policy makers to take action. And they did so before his work could be replicated and tested--a task made difficult because Mr. Mann, a key IPCC author, had refused to release the details for analysis. The scientific community's defense of Mr. Mann was, nonetheless, immediate and harsh. The president of the National Academy of Sciences--as well as the American Meteorological Society and the American Geophysical Union--formally protested, saying that Rep. Barton's singling out of a scientist's work smacked of intimidation.
All of which starkly contrasts to the silence of the scientific community when anti-alarmists were in the crosshairs of then-Sen. Al Gore. In 1992, he ran two congressional hearings during which he tried to bully dissenting scientists, including myself, into changing our views and supporting his climate alarmism. Nor did the scientific community complain when Mr. Gore, as vice president, tried to enlist Ted Koppel in a witch hunt to discredit anti-alarmist scientists--a request that Mr. Koppel deemed publicly inappropriate. And they were mum when subsequent articles and books by Ross Gelbspan libelously labeled scientists who differed with Mr. Gore as stooges of the fossil-fuel industry.
Sadly, this is only the tip of a non-melting iceberg. In Europe, Henk Tennekes was dismissed as research director of the Royal Dutch Meteorological Society after questioning the scientific underpinnings of global warming. Aksel Winn-Nielsen, former director of the U.N.'s World Meteorological Organization, was tarred by Bert Bolin, first head of the IPCC, as a tool of the coal industry for questioning climate alarmism. Respected Italian professors Alfonso Sutera and Antonio Speranza disappeared from the debate in 1991, apparently losing climate-research funding for raising questions.
And then there are the peculiar standards in place in scientific journals for articles submitted by those who raise questions about accepted climate wisdom. At Science and Nature, such papers are commonly refused without review as being without interest. However, even when such papers are published, standards shift. When I, with some colleagues at NASA, attempted to determine how clouds behave under varying temperatures, we discovered what we called an "Iris Effect," wherein upper-level cirrus clouds contracted with increased temperature, providing a very strong negative climate feedback sufficient to greatly reduce the response to increasing CO2. Normally, criticism of papers appears in the form of letters to the journal to which the original authors can respond immediately. However, in this case (and others) a flurry of hastily prepared papers appeared, claiming errors in our study, with our responses delayed months and longer. The delay permitted our paper to be commonly referred to as "discredited." Indeed, there is a strange reluctance to actually find out how climate really behaves. In 2003, when the draft of the U.S. National Climate Plan urged a high priority for improving our knowledge of climate sensitivity, the National Research Council instead urged support to look at the impacts of the warming--not whether it would actually happen.Well, well, well. If you set out to look for man made climate change it seems as if you will find it.
Which brings up another ancient rule. The golden rule. He who has the gold makes the rules.