To: "Janice Lough" <firstname.lastname@example.org>
Subject: Re: liked the paper
Date: Fri Aug 6 09:26:49 2004
Most of the data series in most of the plots have just appeared on the CRU web site.
Go to data then to paleoclimate. Did this to stop getting hassled by the skeptics for the
data series. Mike Mann refuses to talk to these people and I can understand why. They are
just trying to find if we've done anything wrong. I sent one of them loads of series
and he barely said a thankyou. It seems they are now going for Tom Crowley, Lonnie
Thompson and Gordon Jacoby as most of their series are not on web sites.
Below is a link to an awful piece by Legates. He told me he is a writing a paper, but
wrote the press release first ! The pdf is worth getting for a couple of sentences, when
said that MJ restricted their use of paleo series to those that had correlations with
instrumental data ! It is a classic. 'Our uncertainty estimates are based solely on how
the proxy records match the observed data' !
The Legates piece must have been sent to loads of environment correspondents across
the world and a number of op-ed pieces appeared. Some were awful. Most have had
responses from Ray Bradley, Caspar Amman and others.
Hope all is well with you and all the best to all. Glad you enjoyed the paper.
PS Do you want to get involved in IPCC this time? I'm the CLA of the atmospheric obs.
chapter with Kevin Trenberth and we'll be looking for Contributing Authors to help the
Lead Authors we have. Paleo is in a different section this time led by Peck and Eystein
Janssen. Keith is a lead author as well.
Phil Jones has made a valid point in that some of the articles cited
in my critique do not 'directly' address problems with Mann and Jones (MJ)
but rather, address problems with earlier works by Mann, Bradley, and
Hughes (MBH) and other colleagues. Fair enough - I have changed the
critique to reflect that fact. The revised version has been posted since
July 19 at:
However, I still contend that most of my original arguments - namely, the
problems with the shaft, blade, and sheath - apply equally to Mann and
Jones as well as the other Mann et al. manifestations of the 'hockey
MJ incorporate data from a number of the same sources as those used
by MBH; for example, Mann's unpublished PC1 from the western North
American tree-ring data, Cook's Tasmanian tree rings, Thompson's Quelccaya
and Dunde ice core oxygen isotope records (the latter embedded in Yang's
Chinese composite), and Fisher's stacked Greenland ice core oxygen isotope
record. Calibration and verification of MJ includes the flawed MBH curve.
Thus, any errors in MBH effectively undermine the calibration-verification
results of MJ, leaving this study unsupported and any problems with the
underlying common proxies identified in critiques of MBH will also result
in identical problems in MJ.
My criticism regarding the blade is that 0.6 deg C warming for the
last century is noted by the IPCC whereas MJ (and other M et al
representations) have up to 0.95 deg C warming in their observed record.
See MJ's figure 2 where for the global and NH reconstruction, their
estimates for 2000 exceed +0.4 and +0.5 (nearly +0.6), respectively.
MJ's NH curve is included in the attached graph. Thus, I stand by my
criticism of MJ on this point, which is more egregious in MJ than other M
et al representations.
>From Jones: "The trend over the 20th century in the Figure and in the
instrumental data. IPCC quotes 0.6 deg C over the 1901-2000 period. Fact
- but Legates is eyeballing the curve to get 0.95 deg C. A figure isn't
given in Mann and Jones (2003). Take it from me the trend is about the
same as the instrumental record."
Funny, but there IS a figure in MJ - see their Figure 2. As for me
'eyeballing' an apparently non-existent curve, I attach a figure from Soon
et al. (2004) that contains a portion of MJ's Figure 2 to allow others to
decide for themselves whether MJ suggest a twentieth century warming of
0.6 deg C or 0.95 deg C. Moreover, maybe someone can explain why every
time Mann and his colleagues draft another curve, the temperature in 2000
gets warmer and warmer after the fact...
My criticisms regarding the sheath (largely from a paper on which I
am working) stem from the characterization of the uncertainty by MJ that
arises solely from the 'fit' statistics to the 1600-1855 period using
cross-validation with, not observations, but composites of three
previously compiled reconstructions, including that developed by MBH - the
focus of known flaws and errors in the shaft. Note that some of the same
data are used in both MBH and MJ, which doesn't allow for a truly
independent cross-validation. My rather obvious point was not that fit
statistics should not be included (as Jones asserts) but that MJ included
no errors in either input realization (observations or proxy data) or
other obvious sources of error. The claim by MBH and MJ is that only the
model lack-of-fit contributes to uncertainty is inherently flawed.
Considerable errors exist in the representation of both fields -
annual temperatures from both observations and proxy records - and must be
incorporated. Clearly, there is a spatial bias associated with
observations that are biased away from the oceans, high latitudes, and
high altitudes. The spatial problem is far more pronounced when only a
handful of proxies are used to represent the global temperatures at
earlier time periods. Both MBH and MJ are equally guilty in this regard.
David R. Legates
At 15:55 06/08/2004 +1000, you wrote:
Just finished reading your paper with Mike M in Rev of Geophysics which I
very much enjoyed - will let you know when it hits the Mission Beach
Hope all is well
Janice M. Lough
Principal Research Scientist
Australian Institute of Marine Science
PMB 3, Townsville MC
Tel: (07) 47 534248
Fax: (07) 47 725852
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