In his Figure 5 under a section entitled «A New Northern Hemisphere Summer Temperature Record» he shows that the mid to late 20th century temperature as determined from tree ring analysis is far warmer than any period in the past that his analysis includes (this only goes back to 1400 AD). (realclimate.org)
Tree ring analysis by dendrochronologist Mike Baillie, of the Queen's University of Belfast, shows abnormally little growth in Irish oak in 536 and another sharp drop in 542, after a partial recovery. (sciencedaily.com)
Tree ring analysis dated the posts to 1290 to 1250 B.C.E, and excitement grew when preliminary digs unearthed intact pottery and rare Bronze Age textiles. (sciencemag.org)