Combining two different measurements and pretending they are the same thing and mischaracterizing what data show has not been limited to tree ring data. — Prof. Richard EsenbergSure sounds like a pretty devastating indictment, don't it.
Only problem is, that is not at all what was done.
Page 2 of 12:
"Front cover: Northern Hemisphere temperatures were reconstructed for the past 1000 years (up to 1999) using palaeoclimatic records (tree rings, corals, ice cores, lake sediments, etc.), along with historical and long instrumental records. The data are shown as 50-year smoothed differences from the 1961–1990 normal. Uncertainties are greater in the early part of the millennium (see page 4 for further information). For more details, readers are referred to the PAGES newsletter (Vol. 7, No. 1: March 1999, also available at http://www.pages.unibe.ch) and the National Geophysical Data Center (http://www.ngdc.noaa.gov)."
Page 4 of 12:
"Our knowledge of pre-20th century temperature variations in the Northern Hemisphere has increased dramatically in recent years. The availability of natural archives of past temperature such as tree rings, banded corals, ice cores and lake sediments, in addition to historical and long instrumental records, has enabled [Northern Hemisphere] temperature variations to be reconstructed for the last 1000 years at an annual resolution. It is not yet possible to do the same for the Southern Hemisphere due to the lack of adequate palaeoclimatic records. Despite their different emphases on annual or extended summer seasonal temperatures and their different geographical biases, all the reconstructions (shown on the front cover as 50-year smoothed differences from the 1961–1990 normal) indicate that against the background of the millenium as a whole, the 20th century was unusually warm."
The only person pretending and mischaracterizing here is Prof. Esenberg. Why he chooses these hills to die on is anybody's guess.