Last decades of the 20C warmer than in past 400 years

High Confidence in Surface Temp Reconstructions Since A.D. 1600
National Research Council Report.

There is sufficient evidence from tree rings, boreholes, retreating glaciers, and other "proxies" of past surface temperatures to say with a high level of confidence that the last few decades of the 20th century were warmer than any comparable period in the last 400 years, according to a new report from the National Research Council. Less confidence can be placed in proxy-based reconstructions of surface temperatures for A.D. 900 to 1600, said the committee that wrote the report, although the available proxy evidence does indicate that many locations were warmer during the past 25 years than during any other 25-year period since 900. Very little confidence can be placed in statements about average global surface temperatures prior to A.D. 900 because the proxy data for that time frame are sparse, the committee added.
http://nationalacademies.org/morenews/20060622.html

Full text of report
http://fermat.nap.edu/catalog/11676.html