The hypothesis of the IPCC was, and remains, that human greenhouse gas emissions (especially of carbon dioxide) are causing dangerous global warming. The IPCC concentrates its analyses of climate change on only the last few hundred years, and has repeatedly failed to give proper weight to the geological context of the 150-year-long instrumental record. When viewed in historical context, and assessed against empirical data, the greenhouse hypothesis fails. There is no evidence that late-twentieth-century rates of temperature increase were unusually rapid or reached an unnaturally high peak; no human-caused greenhouse signal has been measured or identified despite the expenditure since 1990 of many billions of dollars searching for it; and global temperature, which peaked within the current natural cycle in 1998, has been declining since 2002 despite continuing increases in carbon dioxide emission.Agreed.
Therefore, science reality in 2008 is that the IPCC’s hypothesis of dangerous, human-caused global warming has been repeatedly tested and failed. In contrast, the proper null hypothesis that the global climatic changes that we observe today are natural in origin has yet to be disproven.
(via Maggie's Farm)