Read here. Since the Climategate revelations, the IPCC has literally become the laughingstock of the science community. And more recently, they soiled their reputation even further by pre-announcing what they plan to tell policymakers in 2014. (Objective science? Fuh'get about it!)
Unfortunately for the IPCC, the real science research continues, and much of the new research finds the 2007 IPCC report to be wrong in its assessments and claims.
The latest IPCC "settled science" to become unsettled is the condition of the Antarctic peninsula. It's that piece of slender geography jutting out into the polar ocean that IPCC scientists and Hollywood celebrities tout as the "unprecedented" AGW canary. Ironically, because the climate has changed recently in that area, it's now allowed scientists to conduct more research on the past Antarctic conditions. And the result of those efforts? They've now discovered the canary has had multiple lives there, including during the Medieval Warming Period some 1,000 years ago, before industrial-sized human emissions.
"Hall et al. conclude that "ice was at or behind its present position at ca. 700-970 cal. yr B.P. [Medieval Warming Period] and during at least two earlier times, represented by the dates of shells, in the mid-to-late Holocene," which means, in their words, that "the present state of reduced ice on the western Antarctic Peninsula is not unprecedented,".....This finding thus prompted the U.S. scientists to ask another important question: "How widespread is the event at 700-970 cal yr B.P.?" Starting first with the Antarctic Peninsula itself, they write that (1) "Khim et al. (2002) noted a pronounced high-productivity (warm) event between 500 and 1000 cal. yr B.P. in magnetic susceptibility records from Bransfield Basin," that (2) "dates of moss adjacent to the present ice front in the South Shetland Islands (Hall, 2007) indicate that ice there was no more extensive between ca. 650 and 825 cal. yr B.P. than it is now," and that (3) "Bentley et al. (2009) reported that evidence for warming at this time seems restricted to the Western Antarctic Peninsula and is seen best in some (although not all) marine cores (i.e., Domack et al., 2003)," all of which observations suggest, in their words, that "at least in the western and northern Antarctic Peninsula area," the warmth they discovered "is not an anomalous event."" [Hall, B.L., Koffman, T. and Denton, G.H. 2010]