Comment on "The spatial extent of 20th-century warmth in the context of the past 1200 years".
Osborn and Briffa (Reports, 10 February 2006, p. 841) identified anomalous periods of warmth or cold in the Northern Hemisphere that were synchronous across 14 temperature-sensitive proxies. However, their finding that the spatial extent of 20th-century warming is exceptional ignores the effect of proxy screening on the corresponding significance levels. After appropriate correction, the significance of the 20th-century warming anomaly disappears.
Bürger
Gerd
G
Freie Universität-Berlin, Institut für Meteorologie, Carl-Heinrich-Becker-Weg 6-10, D-12165 Berlin, Germany. gerd.buerger@met.fu-berlin.de