In 2006, Osborn and Briffa published a paper on "The Spatial Extent of 20th-Century Warmth in the Context of the Past 1200 Years", and concluded that "comparison with instrumental temperatures shows the spatial extent of recent warmth to be of greater significance than that during the medieval period." They reexamined the questions raised in the Baliunas and Soon study, but used different statistical methodology, restricted themselves to records that were validated as temperature proxies, and considered the timing of temperature anomalies in different regions to examine whether they had happened at the same time, or were from different periods reflecting local rather than global changes. They found that by far the most widespread warming had occurred after the mid 20th century.
