Monday, December 12, 2011


From: Edward Cook <>
To: Keith Briffa <>
Subject: An idea to pass by you
Date: Wed, 3 Sep 2003 08:32:11 -0400

Hi Keith,

After the meeting in Norway, where I presented the Esper stuff as
described in the extended abstract I sent you, and hearing Bradley's
follow-up talk on how everybody but him has fucked up in
reconstructing past NH temperatures over the past 1000 years (this is
a bit of an overstatement on my part I must admit, but his air of
papal infallibility is really quite nauseating at times), I have come
up with an idea that I want you to be involved in. Consider the
tentative title:

"Northern Hemisphere Temperatures Over The Past Millennium: Where Are
The Greatest Uncertainties?"

Authors: Cook, Briffa, Esper, Osborn, D'Arrigo, Bradley(?), Jones
(??), Mann (infinite?) - I am afraid the Mike and Phil are too
personally invested in things now (i.e. the 2003 GRL paper that is
probably the worst paper Phil has ever been involved in - Bradley
hates it as well), but I am willing to offer to include them if they
can contribute without just defending their past work - this is the
key to having anyone involved. Be honest. Lay it all out on the table
and don't start by assuming that ANY reconstruction is better than
any other.

Here are my ideas for the paper in a nutshell (please bear with me):

1) Describe the past work (Mann, Briffa, Jones, Crowley, Esper, yada,
yada, yada) and their data over-laps.

2) Use the Briffa&Osborn "Blowing Hot And Cold" annually-resolved
recons (plus Crowley?) (boreholes not included) for comparison
because they are all scaled identically to the same NH extra-tropics
temperatures and the Mann version only includes that part of the NH
(we could include Mann's full NH recon as well, but he would probably
go ballistic, and also the new Mann&Jones mess?)

3) Characterize the similarities between series using unrotated
(maybe rotated as well) EOF analysis (correlation for pure
similarity, covariance for differences in amplitude as well) and
filtering on the reconstructions - unfiltered, 20yr high-pass, 100-20
bandpass, 100 lowpass - to find out where the reconstructions are
most similar and different - use 1st-EOF loadings as a guide, the
comparisons of the power spectra could also be done I suppose

4) Do these EOF analyses on different time periods to see where they
differ most, e.g., running 100-year EOF windows on the unfiltered
data, running 300-year for 20-lp data (something like that anyway),
and plot the 1st-EOF loadings as a function of time

5) Discuss where the biggest differences lie between reconstructions
(this will almost certainly occur most in the 100 lowpass data),
taking into account data overlaps

6) Point out implications concerning the next IPCC assessment and EBM
forcing experiments that are basically designed to fit the lower
frequencies - if the greatest uncertainties are in the >100 year
band, then that is where the greatest uncertainties will be in the
forcing experiments

7) Publish, retire, and don't leave a forwarding address

Without trying to prejudice this work, but also because of what I
almost think I know to be the case, the results of this study will
show that we can probably say a fair bit about <100 year
extra-tropical NH temperature variability (at least as far as we
believe the proxy estimates), but honestly know fuck-all about what
the >100 year variability was like with any certainty (i.e. we know
with certainty that we know fuck-all).

Of course, none of what I have proposed has addressed the issue of
seasonality of response. So what I am suggesting is strictly an
empirical comparison of published 1000 year NH reconstructions
because many of the same tree-ring proxies get used in both seasonal
and annual recons anyway. So all I care about is how the recons
differ and where they differ most in frequency and time without any
direct consideration of their TRUE association with observed

I think this is exactly the kind of study that needs to be done
before the next IPCC assessment. But to give it credibility, it has
to have a reasonably broad spectrum of authors to avoid looking like
a biased attack paper, i.e. like Soon and Balliunas.

If you don't want to do it, just say so and I will drop the whole
idea like a hot potato. I honestly don't want to do it without your
participation. If you want to be the lead on it, I am fine with that


Dr. Edward R. Cook
Doherty Senior Scholar and
Director, Tree-Ring Laboratory
Lamont-Doherty Earth Observatory
Palisades, New York 10964 USA
Phone: 845-365-8618
Fax: 845-365-8152

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