Global warming: warmest period globally since 900 CE

Osborne and Briffa have reported in Science that the warm period of the mid-late 20th century has extended over a far greater geographical area than the "Medevil Warm Period" and the "Little Ice Age:"

Periods of widespread warmth or cold are identified by positive or negative deviations that are synchronous across a number of temperature-sensitive proxy records drawn from the Northern Hemisphere. The most significant and longest duration feature during the last 1200 years is the geographical extent of warmth in the middle to late 20th century. Positive anomalies during 890 to 1170 and negative anomalies during 1580 to 1850 are consistent with the concepts of a Medieval Warm Period and a Little Ice Age, but comparison with instrumental temperatures shows the spatial extent of recent warmth to be of greater significance than that during the medieval period.   

Science 10 February 2006:
Vol. 311. no. 5762, pp. 841 - 844
DOI: 10.1126/science.1120514

                                                                                                                                                                                                                  

Full  article in Science (subscription)