The War of the Graphs - Climate Change: Identification and Projections - page 31

When questioned, Overpeck did not confirm or deny whether he had
made such a statement, but he did write the email 3 with the subject “The new
“warm period myths””, addressed to Keith Briffa in 2005: “I get the sense
that I am not the only one who would like to deal a mortal blow to
the misuse of supposed warm period terms and myths in the literature….pure
rubbish”. He also asks whether Mr. Briffa has any “cool” figures in this
regard. Mr. Briffa is indeed the author of a reconstruction, made famous
after being truncated by Phil Jones (Director of the CRU ), in order to “hide
the decline” 4 . Indeed, from the 1960s, proxies have indicated a decline,
which is incompatible with the increase in thermometric temperatures.
Michael Mann has a similar mindset, writing to Phil Jones in 2003, and
copying in other luminaries of the climatological community
(including Overpeck): “It would be nice to try to “contain” the putative
“Medieval Warm Period”” 5 . In the Jones & Mann reconstruction included in
our datasets, the medieval peak is not completely hidden, as it was in the
original hockey stick graph, but it has indeed been extremely well
“contained”.
On the other hand, the Loehle reconstruction shows the highest medieval
temperatures in our collection, up to 0.3 or 0.4 ° C higher than in the Jones &
Mann reconstruction, though without reaching the levels of the Lamb graph.
Loehle, member of the Society of American Foresters and an expert in his
field, preferred to eliminate the proxies given by tree rings, which were
given pride of place by Jones and Mann, and are known for their tendency to
reduce large-scale climatic variations. It was harshly received: “… The
Loehle paper is awful as you know…” 6 . In AR5, (Chapter 5: Information
from Paleoclimate Archives), Table 5.1 nevertheless includes this
reconstruction, with the warning “almost no tree rings”.
3 These emails were not intended to be made public. But since “Climategate”, they could no
longer be ignored.
4 Email from 16/11/99, from Phil Jones to: R. Bradley, M. Mann, M. Hughes Cc: K. Briffa,
T. Osborn: “… I've just completed Mike's Nature trick of adding in the real temps to each
series for the last 20 years (ie from 1981 onwards) and from 1961 for Keith's to hide the
decline….”.
5 Email from 04/06/2003, from Michael Mann to Phil Jones, R. Bradley, Keith Briffa, Tom
Crowley, Michael Oppenheimer, Jonathan Overpeck, Kevin Trenberth, Tom Wigley.
6 Email from 05/12/2007, from Phil Jones to Michael Mann.