Alleged CRU Emails - 25 results below

The below are part of a series of alleged emails from the Climate Research Unit at the University of East Anglia, released on 20 November 2009.

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Original Filename: 1141068509.txt | Return to the index page | Permalink | Earlier Emails | Later Emails

From: "Rob Wilson" <rob.wilson@xxxxxxxxx.xxx>
To: "Tim Osborn" <t.osborn@xxxxxxxxx.xxx>
Subject: Re: Emailing: Wilson et al. technical comment
Date: Mon, 27 Feb 2006 14:28:xxx xxxx xxxx
Reply-to: "Rob Wilson" <rob.wilson@xxxxxxxxx.xxx>
Cc: "rosanne" <rdd@xxxxxxxxx.xxx>, <K.briffa@xxxxxxxxx.xxx>

Hi Tim,

yes, we processed our own RCS chronology using Jan's Jaemtland data.

I also agree that using Jaemtland or not would make little difference to the results.

Rosanne is presenting at this NAS meeting on Thursday which McIntyre is obviously going to
use as a forum to muddy the waters even further. He has given us a hard time about the use
of Gaspe and the Polar Urals chronologies and their influence on the 'hockey stick' trend
over the past 2 centuries. However, removing these series makes little difference to our
results in the past few centuries.

am just going through your e-mails w.r.t. the coral paper - it is a huge help

thanks

Rob

----- Original Message -----

From: [1]Tim Osborn

To: [2]Rob Wilson

Cc: [3]rosanne ; [4]K.briffa@xxxxxxxxx.xxx

Sent: Monday, February 27, 2006 2:23 PM

Subject: Re: Emailing: Wilson et al. technical comment

Thanks for the very clear answers Rob.
We didn't use Jaemtland and you did, that is why McIntyre suggested
that we disagreed. But in fact our reason for excluding it was not
that it didn't correlate with temperature positively, but that we
didn't even calculate a correlation because the RCS chronology series
we received stopped in 1827 rather than 1978.
It is true that the full set of core data from Jan Esper span the
range 1xxx xxxx xxxx, but the RCS chronology we received spanned the range
1xxx xxxx xxxxonly - and this matches the replication diagram in Esper et
al.
([5]http://www.sciencemag.org/content/vol295/issue5563/images/data/2250/DC1/1066208S2_me
d.gif)
which stops then for Jaemtland.
Presumably you obtained the set of core data and did your own RCS
processing etc., rather than using the Esper et al. RCS chronologies?
Anyway, I think that clears up our supposed "differences" over
Jaemtland, though do let me know if you have any more points to
add. Our results would have been very little affected by including
Jaemtland anyway!
Cheers
Tim
At 09:58 25/02/2006, Rob Wilson wrote:
>Moring Tim,
>answers in red.
>
>
>on a related matter, Science have forwarded me some
>questions/requests from McIntyre about our paper that they'd like our
>response to. One of them states that "D'Arrigo et al. (2006) have
>reported directly opposite findings in respect to the correlation
>between their RCS chronology and gridcell temperature for Jaemtland
>and the two foxtail series."
>I am not sure where he got that from.
>We used Jaemtland - it is a good site.
>We did not use the foxtail data for similar reasons for us not using
>the Bristlecone pine data (see below) .
>
>We didn't give a correlation for Jaemtland so it is hard for you to
>have obtained the "opposite of nothing"! But anyway, I wanted to ask
>whether in fact your Jaemtland differed from the one we used. The
>one we used should be the same as Esper et al., with data provided by
>Ed Cook. You seem to be citing Naurzbaev and Vaganov (1999) for your
>Jaemtland record which seems odd. And its start and finish years
>differ from the series I got, so I'm guessing that the data are
>different and thus there's no reason why different data would have
>consistent correlations. Also, do you know what correlation and for
>what season (annual-mean?) you got for Jaemtland?
>We also used the Esper data.
>The N+V reference is completely wrong. I checked with Rosanne. Not
>sure how that got in. The N+V reference is actually for Taymir.
>Apologies for that - hopefully there are no more mistakes like that.
>Anyway, to clarify what we did to the data, here is an exert from
>the report I wrote for Rosanne 2 years ago.
>
>"The data from this site were those utilised by Jan Esper for his
>Science paper. After removing a few low correlated series, the final
>data-set consists of 156 radii over the period 1xxx xxxx xxxx.
>Unfortunately however, the period 1xxx xxxx xxxxis represented by only
>one radius and replication is only reasonable from the mid 14th century. "
>
>In the end, I used the period represented by 10 or more series - 1xxx xxxx xxxx.
>This should agree with the data you have.
>
>As for correlations with temperature, Jaemtland is OK.
>Against the relevant local 5x5 Land CRU (version 1) grid, the STD
>and RCS chrons correlate with the Jun-Sep season at 0.48 over the
>1xxx xxxx xxxxperiod. No residual problems were found with this
>relationship. All screening was done up to 1970 so that potential
>divergence would not effect the screening process. In this situation
>though, there was no divergence for the 1xxx xxxx xxxxperiod.
>
>
>On your (D'Arrigo et al.) exclusion of the Boreal/Upperwright series,
>it wasn't clear which (one or more) of the 3 reasons listed applied
>to these: (1) no significant temperature correlation, (2) significant
>precip correlation, (3) too far south.
>I know that the temperature signal is debatable in such records, but
>I seem to recall you saying that on the longer time scales they (and
>I think you were referring to Boreal/Upperwright, but I may have been
>mistaken) showed some agreement with the N. American series from this
>recent paper, giving some support at least for a temperature
>signal. Is my recollection correct?
>As I said earlier, I did not look at the Foxtail data.
>However, I have played with the BP data.
>The sites I utilised are described in this extract.
>
>"Of the 10 Bristlecone pine chronologies sent to me, 3 chronologies
>were identified to express a significant summer temperature signal
>using correlation analysis against local gridded data. These three
>sites also load upon the same principal component in a PCA using all
>10 chronologies. These three sites are: Hermit Hill (N = 38;
>1xxx xxxx xxxx) and Windy Ridge (N = 29; 1xxx xxxx xxxx) from Colorado and
>Sheep Mountain (N = 71; xxx xxxx xxxx) from California (Figure 1)."
>
>The correlation of the STD and RCS chronologies against local
>gridded July-Sep mean temperatures is 0.38 and 0.34 respectively.
>
>I have also showed you a comparative plot of the RCS chronology with
>my North American average series and the comparison is pretty good
>for most of the record and certainly there does not seem to be any
>obvious inflation of index values in the 20th century.
>
>So - why did we not use this site:
>well
>(1) Steve Macintyre was kicking up a fuss about these data and we
>felt that perhaps it might be opening us to criticism if we used them
>(2) These data are have been reported to also show a precipitation
>signal. I did some analysis on a site basis, but cannot find the
>results. However, the precipiation signal in the 3 chrons used was
>also weak. The temperature signal is stronger. This agrees with the
>BP vs NA chronology comparison.
>(3) As this was a low latitude site, then we would also need to
>include other low latitude sites - e.g. from the Himalayas. Jan
>would not let me use his data for this region, so in the end, we
>decided to keep the data-set as high latitude as possible. Quebec,
>Alps and Mongolia being the most southerly sites.
>
>I hope this answers your queries. Rosanne is presenting at the NAS
>meeting next week, and we have been trying to address many of the
>criticisms of Macintyre that he is posting on his blog. I think Jan
>making his data available was probably bad timing.
>
>Rob
Dr Timothy J Osborn
Climatic Research Unit
School of Environmental Sciences, University of East Anglia
Norwich NR4 7TJ, UK
e-mail: [6]t.osborn@xxxxxxxxx.xxx
phone: xxx xxxx xxxx
fax: xxx xxxx xxxx
web: [7]http://www.cru.uea.ac.uk/~timo/
sunclock: [8]http://www.cru.uea.ac.uk/~timo/sunclock.htm

References

1. mailto:t.osborn@xxxxxxxxx.xxx
2. mailto:rob.wilson@xxxxxxxxx.xxx
3. mailto:rdd@xxxxxxxxx.xxx
4. mailto:K.briffa@xxxxxxxxx.xxx
5. http://www.sciencemag.org/content/vol295/issue5563/images/data/2250/DC1/1066208S2_med.gif
6. mailto:t.osborn@xxxxxxxxx.xxx
7. http://www.cru.uea.ac.uk/~timo/
8. http://www.cru.uea.ac.uk/~timo/sunclock.htm

Original Filename: 1141072471.txt | Return to the index page | Permalink | Earlier Emails | Later Emails

From: Jonathan Overpeck <jto@u.arizona.edu>
To:

Original Filename: 1141143688.txt | Return to the index page | Permalink | Earlier Emails | Later Emails

From: Jonathan Overpeck <jto@u.arizona.edu>
To: Tim Osborn <t.osborn@xxxxxxxxx.xxx>
Subject: Re: latest draft of 2000-year section text
Date: Tue, 28 Feb 2006 11:21:xxx xxxx xxxx
Cc: Keith Briffa <k.briffa@xxxxxxxxx.xxx>, rahmstorf@xxxxxxxxx.xxx, cddhr@xxxxxxxxx.xxx, joos <joos@xxxxxxxxx.xxx>, Eystein Jansen <eystein.jansen@xxxxxxxxx.xxx>

<x-flowed>
Hi Tim, Keith and Stefan - We certainly can't get into the details of
the debate, both for space reasons, and because K & T have gotten us
away from the more "defensive" impression our FOD gave reviewers and
others. Although I share Stefan's concern that we almost have to
hammer the misinformation to death, I think we'll be ok dealing with
it succinctly, and focusing on the bigger picture - Mann et al., and
all the controversy is history - we know much more now, and it makes
for stronger statements. Keith and Tim have done a nice job balancing
all this, and we have to hope that all the Mann et al controversy
will start sounding as dated as it is. I know I make that point
pretty clearly when I talk to the media.

BUT, I leave it to Keith and Tim to tweak the discussion to reflect
Stafan's concern as appropriate.

thanks, Peck

>Hi Stefan,
>
>our (Keith and mine) understanding of this issue is that Burger et
>al. (2006, Tellus, already published and therefore citable) already
>point out the von Storch et al. (2004) mistake in implementing the
>Mann et al. (1998) method. But we haven't stated this (or cited the
>Science in press comment) because Burger et al. also demonstrate
>that when they implement the method without the detrending step
>(i.e., following the Mann et al. approach more accurately than von
>Storch et al. did) then the bias is still there, though of smaller
>magnitude than von Storch et al. (2004) suggested. Given that we
>already say that the extent of any bias is uncertain, it does not
>seem necessary to go into the details any further by discussing the
>implementation by von Storch et al. of the Mann et al. method.
>
>Finally, I think (though here it is less clear from their paper and
>I am relying on my recollection of talking to Gerd Burger) that
>Burger et al. also show that the amount of noise von Storch et al.
>added to create the pseudo-proxies yields a pseudo-reconstruction
>that has much better verification skill than obtained by Mann et al.
>(1998) for their real reconstruction. If they increase the noise
>added (deteriorating the "skill" of the pseudo-proxies) until they
>get similar verification statistics as Mann et al. report, then the
>size of the bias gets bigger. In fact, the bias they obtain with
>the higher noise but "correct" no-detrending method is actually very
>similar to the bias von Storch et al. reported with lower noise but
>incorrect detrending method! So where does that leave us? I don't
>think there's room to put all this in. Of course the magnitude of
>the bias cannot be determined from any pseudo-proxy simulation
>anyway, and will be different for different models.
>
>We'd be interested to know if your (or others on the cc list)
>interpretation of Burger et al. (2006) is significantly different to
>this.
>
>Cheers
>
>Tim
>
>At 16:42 28/02/2006, Stefan Rahmstorf wrote:
>>Hi Keith and others,
>>
>>attached is the draft Keith sent on 21 Feb of the 2000-year
>>section, with comments and edits (grey) from me.
>>
>>I note that Von Storch et al. 2004 is cited without it being
>>mentioned that they did not implement the Mann et al. method
>>correctly - by detrending before calibration, the performance of
>>the method was greatly degraded in their model. I guess you left
>>this out because the comment to Science showing this is still in
>>press? Will it be added once this has been published? I think it is
>>a major point, as it was such a high-profile paper - Von Storch's
>>contention that the "hockey stick" is "nonsense" (cited in the US
>>Senate) is based on a mistake.
>>
>>Cheers, Stefan
>>
>>--
>>To reach me directly please use: rahmstorf@xxxxxxxxx.xxx
>>(My former addresses @pik-potsdam.de are read by my assistant Brigitta.)
>>
>>Stefan Rahmstorf
>>www.ozean-klima.de
>>www.realclimate.org
>>
>>
>
>Dr Timothy J Osborn
>Climatic Research Unit
>School of Environmental Sciences, University of East Anglia
>Norwich NR4 7TJ, UK
>
>e-mail: t.osborn@xxxxxxxxx.xxx
>phone: xxx xxxx xxxx
>fax: xxx xxxx xxxx
>web: http://www.cru.uea.ac.uk/~timo/
>sunclock: http://www.cru.uea.ac.uk/~timo/sunclock.htm

--
Jonathan T. Overpeck
Director, Institute for the Study of Planet Earth
Professor, Department of Geosciences
Professor, Department of Atmospheric Sciences

Mail and Fedex Address:

Institute for the Study of Planet Earth
715 N. Park Ave. 2nd Floor
University of Arizona
Tucson, AZ 85721
direct tel: xxx xxxx xxxx
fax: xxx xxxx xxxx
http://www.geo.arizona.edu/
http://www.ispe.arizona.edu/
</x-flowed>

Original Filename: 1141145428.txt | Return to the index page | Permalink | Earlier Emails | Later Emails

From: Jonathan Overpeck <jto@u.arizona.edu>
To: "Wahl, Eugene R" <wahle@xxxxxxxxx.xxx>
Subject: Fwd: RE: Wahl Ritson Ammann Science article on vonStorch 04
Date: Tue, 28 Feb 2006 11:50:xxx xxxx xxxx
Cc: "Keith Briffa" <k.briffa@xxxxxxxxx.xxx>, "Eystein Jansen" <eystein.jansen@xxxxxxxxx.xxx>, "Caspar Ammann" <ammann@xxxxxxxxx.xxx>, rahmstorf@xxxxxxxxx.xxx, Eystein Jansen <eystein.jansen@xxxxxxxxx.xxx>

<x-flowed>
Eugene - quite timely. Keith and Tim are doing the final revision
tomorrow, and we've actually been debating if the vonStorch issue was
handled just right.

thx, peck

>X-Sieve: CMU Sieve 2.2
>Subject: RE: Wahl Ritson Ammann Science article on vonStorch 04
>Date: Tue, 28 Feb 2006 13:38:xxx xxxx xxxx
>Thread-Topic: Wahl Ritson Ammann Science article on vonStorch 04
>Thread-Index: AcY3ZrWjPf6A8R9vTWeSE3GvqmgKLAFLDcogAACcoIA=
>From: "Wahl, Eugene R" <wahle@xxxxxxxxx.xxx>
>To: "Jonathan Overpeck" <jto@u.arizona.edu>
>Cc: "Keith Briffa" <k.briffa@xxxxxxxxx.xxx>,
> "Eystein Jansen" <eystein.jansen@xxxxxxxxx.xxx>,
> "Caspar Ammann" <ammann@xxxxxxxxx.xxx>
>
>Sorry, I sent the message without the text. [The "send" button is next
>to the "insert" button on my software!!] Here it is.
>
>-----Original Message-----
>From: Wahl, Eugene R
>Sent: Tuesday, February 28, 2006 1:32 PM
>To: 'Jonathan Overpeck'
>Cc: Keith Briffa; Eystein Jansen; 'Caspar Ammann'
>Subject: RE: Wahl Ritson Ammann Science article on vonStorch 04
>
>Hello Jonathan, Keith, and Eystein:
>
>I don't yet have any word from Steve Schneider concerning the
>Wahl-Ammann article on the MBH/MM issues...
>
>...HOWEVER, here is something that slipped under my radar screen, about
>which I should have made you aware previously. I've attached the
>ACCEPTED version of the Wahl-Ritson-Ammann comment article on the
>vonStorch et al. 2004 Science paper. This the article that criticizes
>MBH for very large low-frequency amplitude losses. The final acceptance
>from Science just came TODAY, and is copied below.
>
>In this comment article (specifically requested to be expanded to 1000
>words by the Science editors), we note that the calibration and
>verification performance of the MBH method as implemented in VS04 show
>really poor LF fidelity--which cannot happen if the MBH method is
>implemented according to its original form. We note this, which is
>explained by a significant omission on the part of VS04 in implementing
>the MBH methodology (a detrending step that was only disclosed later
>last year in a conference proceedings paper). We also comment on
>physical and statistical reasons why detrending is not appropriate in
>this context. We conclude that the large amplitude losses VS04 claims
>are simply not correct.
>
>I am imagining that this contextualization of the VS04 critique would
>also be relevant for your chapter, and it can now be considered "in
>press" as the from our Science correspondent notes below. I would think
>this acceptance makes it "citable". If not, I understand.
>
>
>NOTE THAT THIS ARTICLE IS SUBJECT TO THE USUAL SCIENCE EMBARGO RULES. I
>DO NOT BELIEVE THAT THIS MEANS CITATION IS EMBARGOED. (Cf. 5th
>paragraph in copied message below, which supports citation.)
>
>
>Peace, Gene
>
>*******************************
>
>Dr. Eugene R. Wahl
>Asst. Professor of Environmental Studies
>Alfred University
>
>607.871.2604
>
>
>********************** copied message below ********************
>
>
>February 28, 2006 received 10:31 am EST
>
>Dear Dr. Wahl,
>
>Below is the formal acceptance of your manuscript. The paper is
>technically not "in press" yet, though I assume that either "accepted"
>or "in press" would be acceptable.
>
>
>Dear Dr. Wahl,
>
>We are pleased to accept your revised Technical Comment on the paper by
>von Storch et al. for publication.
>
>The text of your comment will be edited to conform to *Science* style
>guidelines. Before publication you will receive galley proofs for
>author corrections. Please return the marked and corrected proofs, by
>fax or overnight express, within 48 hours of receipt.
>
>For authors with NIH grants intending to deposit the accepted version of
>their paper on PubMed Central, the following text must be displayed as a
>footnote with an asterisk to the manuscript title:
>
>"This manuscript has been accepted for publication in Science. This
>version has not undergone final editing. Please refer to the complete
>version of record at http://www.sciencemag.org/. This manuscript may
>not be reproduced or used in any manner that does not fall within the
>fair use provisions of the Copyright Act without the prior, written
>permission of AAAS."
>
>As noted in our License for Publication, the manuscript cannot be posted
>sooner than 6 months after final publication of the paper in Science.
>
>As you know, the full text of technical comments and responses appears
>on our website, Science Online, with abstracts published in the Letters
>section of the print *Science*.
>
>Thanks for your patience during this long process, and thanks for
>publishing in *Science*.
>
>Sincerely,
>
>Tara S. Marathe
>Associate Online Editor, Science
>tmarathe@xxxxxxxxx.xxx
>
>*********************** end copied message ******************
>
>Content-Type: application/msword;
> name="1120866RevisedText.doc"
>Content-Description: 1120866RevisedText.doc
>Content-Disposition: attachment;
> filename="1120866RevisedText.doc"
>
>
>Content-Type: image/jpeg;
> name="1120866Fig.jpg"
>Content-Description: 1120866Fig.jpg
>Content-Disposition: attachment;
> filename="1120866Fig.jpg"
>

--
Jonathan T. Overpeck
Director, Institute for the Study of Planet Earth
Professor, Department of Geosciences
Professor, Department of Atmospheric Sciences

Mail and Fedex Address:

Institute for the Study of Planet Earth
715 N. Park Ave. 2nd Floor
University of Arizona
Tucson, AZ 85721
direct tel: xxx xxxx xxxx
fax: xxx xxxx xxxx
http://www.geo.arizona.edu/
http://www.ispe.arizona.edu/
</x-flowed>

Attachment Converted: "c:eudoraattach1120866RevisedText1.doc"

Attachment Converted: "c:eudoraattach1120866Fig1.jpg"

Original Filename: 1141151539.txt | Return to the index page | Permalink | Earlier Emails | Later Emails

From: "Wahl, Eugene R" <wahle@xxxxxxxxx.xxx>
To: "Jonathan Overpeck" <jto@u.arizona.edu>
Subject: RE: Wahl Ritson Ammann Science article on vonStorch 04
Date: Tue, 28 Feb 2006 13:32:xxx xxxx xxxx
Cc: "Keith Briffa" <k.briffa@xxxxxxxxx.xxx>, "Eystein Jansen" <eystein.jansen@xxxxxxxxx.xxx>, "Caspar Ammann" <ammann@xxxxxxxxx.xxx>

Hello Jonathan, Keith, and Eystein:

I don't yet have any word from Steve Schneider concerning the
Wahl-Ammann article on the MBH/MM issues...

...HOWEVER, here is something that slipped under my radar screen, about
which I should have made you aware previously. I've attached the
ACCEPTED version of the Wahl-Ritson-Ammann comment article on the
vonStorch et al. 2004 Science paper. This the article that criticizes
MBH for very large low-frequency amplitude losses. The final acceptance
from Science just came today, and is copied below.

In this comment article (specifically requested to be expanded to 1000
words by the Science editors), we note that the calibration and
verification performance of the MBH method as implemented in VS04 show
really poor LF fidelity--which cannot happen if the MBH method is
implemented according to its original form. We note this, which is
explained by a significant omission on the part of VS04 in implementing
the MBH methodology (a detrending step that was only disclosed later
last year in a conference proceedings paper). We also comment on
physical and statistical reasons why detrending is not appropriate in
this context. We conclude that the large amplitude losses VS04 claims
are simply not correct.

I am imagining that this contextualization of the VS04 critique would
also be relevant for your chapter, and it can now be considered "in
press" as the from our Science correspondent notes below. I would think
this acceptance makes it "citable". If not, I understand.

NOTE THAT THIS ARTICLE IS SUBJECT TO THE USUAL SCIENCE EMBARGO RULES. I
DO NOT BELIEVE THAT THIS MEANS CITATION IS EMBARGOED. (Cf. 4th
paragraph in copied message below that supports citation.)

Peace, Gene

*******************************

Dr. Eugene R. Wahl
Asst. Professor of Environmental Studies
Alfred University

607.871.2604

********************** copied message below ********************

Dear Dr. Wahl,

Below is the formal acceptance of your manuscript. The paper is
technically not "in press" yet, though I assume that either "accepted"
or "in press" would be acceptable.

Dear Dr. Wahl,

We are pleased to accept your revised Technical Comment on the paper by
von Storch et al. for publication.

The text of your comment will be edited to conform to *Science* style
guidelines. Before publication you will receive galley proofs for
author corrections. Please return the marked and corrected proofs, by
fax or overnight express, within 48 hours of receipt.

For authors with NIH grants intending to deposit the accepted version of
their paper on PubMed Central, the following text must be displayed as a
footnote with an asterisk to the manuscript title:

"This manuscript has been accepted for publication in Science. This
version has not undergone final editing. Please refer to the complete
version of record at http://www.sciencemag.org/. This manuscript may
not be reproduced or used in any manner that does not fall within the
fair use provisions of the Copyright Act without the prior, written
permission of AAAS."

As noted in our License for Publication, the manuscript cannot be posted
sooner than 6 months after final publication of the paper in Science.

As you know, the full text of technical comments and responses appears
on our website, Science Online, with abstracts published in the Letters
section of the print *Science*.

Thanks for your patience during this long process, and thanks for
publishing in *Science*.

Sincerely,

Tara S. Marathe
Associate Online Editor, Science
tmarathe@xxxxxxxxx.xxx

*********************** end copied message ******************

Original Filename: 1141164645.txt | Return to the index page | Permalink | Earlier Emails | Later Emails

From: Tim Osborn <t.osborn@xxxxxxxxx.xxx>
To: Stefan Rahmstorf <rahmstorf@xxxxxxxxx.xxx>, Keith Briffa <k.briffa@xxxxxxxxx.xxx>
Subject: Re: latest draft of 2000-year section text
Date: Tue, 28 Feb 2006 17:10:45 +0000
Cc: jto@u.arizona.edu,eystein.jansen@xxxxxxxxx.xxx, Fortunat Joos <joos@xxxxxxxxx.xxx>,drind@xxxxxxxxx.xxx

<x-flowed>
Hi Stefan,

our (Keith and mine) understanding of this issue is that Burger et
al. (2006, Tellus, already published and therefore citable) already
point out the von Storch et al. (2004) mistake in implementing the
Mann et al. (1998) method. But we haven't stated this (or cited the
Science in press comment) because Burger et al. also demonstrate that
when they implement the method without the detrending step (i.e.,
following the Mann et al. approach more accurately than von Storch et
al. did) then the bias is still there, though of smaller magnitude
than von Storch et al. (2004) suggested. Given that we already say
that the extent of any bias is uncertain, it does not seem necessary
to go into the details any further by discussing the implementation
by von Storch et al. of the Mann et al. method.

Finally, I think (though here it is less clear from their paper and I
am relying on my recollection of talking to Gerd Burger) that Burger
et al. also show that the amount of noise von Storch et al. added to
create the pseudo-proxies yields a pseudo-reconstruction that has
much better verification skill than obtained by Mann et al. (1998)
for their real reconstruction. If they increase the noise added
(deteriorating the "skill" of the pseudo-proxies) until they get
similar verification statistics as Mann et al. report, then the size
of the bias gets bigger. In fact, the bias they obtain with the
higher noise but "correct" no-detrending method is actually very
similar to the bias von Storch et al. reported with lower noise but
incorrect detrending method! So where does that leave us? I don't
think there's room to put all this in. Of course the magnitude of
the bias cannot be determined from any pseudo-proxy simulation
anyway, and will be different for different models.

We'd be interested to know if your (or others on the cc list)
interpretation of Burger et al. (2006) is significantly different to this.

Cheers

Tim

At 16:42 28/02/2006, Stefan Rahmstorf wrote:
>Hi Keith and others,
>
>attached is the draft Keith sent on 21 Feb of the 2000-year section,
>with comments and edits (grey) from me.
>
>I note that Von Storch et al. 2004 is cited without it being
>mentioned that they did not implement the Mann et al. method
>correctly - by detrending before calibration, the performance of the
>method was greatly degraded in their model. I guess you left this
>out because the comment to Science showing this is still in press?
>Will it be added once this has been published? I think it is a major
>point, as it was such a high-profile paper - Von Storch's contention
>that the "hockey stick" is "nonsense" (cited in the US Senate) is
>based on a mistake.
>
>Cheers, Stefan
>
>--
>To reach me directly please use: rahmstorf@xxxxxxxxx.xxx
>(My former addresses @pik-potsdam.de are read by my assistant Brigitta.)
>
>Stefan Rahmstorf
>www.ozean-klima.de
>www.realclimate.org
>
>
>

Dr Timothy J Osborn
Climatic Research Unit
School of Environmental Sciences, University of East Anglia
Norwich NR4 7TJ, UK

e-mail: t.osborn@xxxxxxxxx.xxx
phone: xxx xxxx xxxx
fax: xxx xxxx xxxx
web: http://www.cru.uea.ac.uk/~timo/
sunclock: http://www.cru.uea.ac.uk/~timo/sunclock.htm

</x-flowed>

Original Filename: 1141169545.txt | Return to the index page | Permalink | Earlier Emails | Later Emails

From: Stefan Rahmstorf <rahmstorf@xxxxxxxxx.xxx>
To: Tim Osborn <t.osborn@xxxxxxxxx.xxx>
Subject: Re: latest draft of 2000-year section text
Date: Tue, 28 Feb 2006 18:32:25 +0100
Cc: Keith Briffa <k.briffa@xxxxxxxxx.xxx>, jto@u.arizona.edu, eystein.jansen@xxxxxxxxx.xxx, Fortunat Joos <joos@xxxxxxxxx.xxx>, drind@xxxxxxxxx.xxx

Hi Tim,
my simplistic interpretation as an outside observer of this field is:
VS04 published a high-profile analysis in Science concluding that the performance of the
MBH method is disastrously bad. Subsequently, VS in the media called the MBH result
"nonsense", accused Nature of putting their sales interests above peer review when
publishing MBH, and called the IPCC "stupid" and "irresponsible" for highlighting the
results of MBH. This had *major* political impact - I know this e.g. from EU negotiators
who were confronted with this stuff by their US colleagues.
Then it turns out that they implemented the method incorrectly. If it is done as MBH did,
variance is still somewhat underestimated in the same pseudoproxy test, but only a little,
within the error bars given by MBH and shown by IPCC. Certainly nothing dramatic - one
could conclude that the method works reasonably well but needs improvement. This would have
been a technical discussion with not much political impact.
What VS and their colleagues are doing now, rather than publishing a correction of their
mistake, is saying: "well, but if we add a lot more noise, or use red noise, then the MBH
method is still quite bad..."
The question here is: should our IPCC chapter say something to correct the wrong impression
which had the political impact, namely that the MBH method is disastrously bad? This is not
the same as the legitimate discussion about the real errors in proxy reconstructions, which
accepts that these reconstructions have some errors but are still quite useful, rather than
being "nonsense".
Cheers, Stefan
--
To reach me directly please use: [1]rahmstorf@xxxxxxxxx.xxx
(My former addresses @pik-potsdam.de are read by my assistant Brigitta.)

Stefan Rahmstorf
[2]www.ozean-klima.de
[3]www.realclimate.org

References

1. mailto:rahmstorf@xxxxxxxxx.xxx
2. http://www.ozean-klima.de/
3. http://www.realclimate.org/

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From: "Wahl, Eugene R" <wahle@xxxxxxxxx.xxx>
To: "Jonathan Overpeck" <jto@u.arizona.edu>
Subject: RE: Wahl Ammann Climatic Change article on MBH/MM
Date: Tue, 28 Feb 2006 21:42:xxx xxxx xxxx
Cc: "Keith Briffa" <k.briffa@xxxxxxxxx.xxx>, "Eystein Jansen" <eystein.jansen@xxxxxxxxx.xxx>, "Caspar Ammann" <ammann@xxxxxxxxx.xxx>

Hello all:

Good news this day. The Wahl-Ammann paper also has been given fully accepted status today by Stephen Schneider. I copy his affirmation of this below, and after that his remark from earlier this month regarding this status being equivalent to "in press". I hope this meets the deadline of before March 1 for citation.

Peace, Gene

********************************* first copied message **************************************

RE: provision of Wahl and Ammann ms 3321 to NAS committee
Stephen H Schneider [shs@xxxxxxxxx.xxx]
You replied on 2/28/2006 9:33 PM.
Follow up
To: Wahl, Eugene R
Cc: katarina kivel

Hello from Sydney. I have now read your responses the the rereviewer and
am satisfied you have done more than an adequate job. The paper is now
accepted and you can post it where you wish with that designation. Let me
know if there is anything else to do. Congratulations, Steve

********************************* second copied message **************************************

RE: Wahl and Ammann ms 3321
Stephen H Schneider [shs@xxxxxxxxx.xxx]
You replied on 2/28/2006 7:06 PM.
Follow up
To: Wahl, Eugene R
Cc: katarina kivel

your interpretation is fine--get me the revision soon so I have time to
assess your responses in light of reviews in time! Look forward to
recievieng it, Steve

On Sat, 11 Feb 2006, Wahl, Eugene R wrote:

> Hello Steve:
>
> Caspar and I expect to have the final manuscript to you in xxx xxxx xxxxdays with all the revisions you requested in December. I have recently had some correspondance with Jonathan Overpeck about this, in his IPCC role. He says that the paper needs to be in press by the end of February to be acceptable to be cited in the SOD. [I had thought that we had passed all chance for citation in the next IPCC report back in December, but Peck has made it known to me this is not so.]
>
> He and I have communicated re: what "in press" means for Climatic Change, and I agreed to contact you to have a clear definition. What I have understood from our conversations before is that if you receive the mss and move it from "provisionally accepted" status to "accepted", then this can be considered in press, in light of CC being a journal of record.
>
> Peace, Gene
> Dr. Eugene R. Wahl
> Asst. Professor of Environmental Studies
> Alfred University
>

*************************** end of copied messages *********************

Dr. Eugene R. Wahl
Asst. Professor of Environmental Studies
Alfred University

xxx xxxx xxxx
1 Saxon Drive
Alfred, NY 14802

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From: Susan Solomon <ssolomon@xxxxxxxxx.xxx>
To: <wg1-ar4-las@xxxxxxxxx.xxx>, wg1-ar4-las@xxxxxxxxx.xxx, <wg1-ar4-re@xxxxxxxxx.xxx>, wg1-ar4-re@xxxxxxxxx.xxx
Subject: [Wg1-ar4-las] Inappropriate Press Reports
Date: Wed, 1 Mar 2006 10:17:xxx xxxx xxxx
Cc: renate christ <RChrist@xxxxxxxxx.xxx>, bubu jallow2 <dwr@xxxxxxxxx.xxx>, bubu jallow1 <bubujallow@xxxxxxxxx.xxx>, Jian Liu <Jianliu@xxxxxxxxx.xxx>, jouzel <jouzel@xxxxxxxxx.xxx>, IPCC Chair <chairipcc@xxxxxxxxx.xxx>

Dear Colleagues,
It has come to our attention that certain preliminary results of the WG1 draft report may
have been provided inappropriately to the press, particularly the Guardian and the BBC.
Due to the nature of some of the specific material now appearing in the press (i.e.,
specific numbers discussed in our last LA meeting but not yet presented to others; see
http://www.guardian.co.uk/frontpage/story/0,,1719608,00.html),
and the nature in which it is being cited (i.e., a 'source' as indicated in
http://news.bbc.co.uk/1/hi/sci/tech/4761804.stm), there may be a connection to someone
inside our team, and this is both extremely disappointing and concerning to us.

As you will all be well aware, all of our findings are currently under development and
cannot be quoted or cited until the report is officially finalized at the end of January,
2007. Please do not give anyone the impression that you can currently represent
information on behalf of the IPCC, or provide information about the draft material in the
report. To do so would be not only a great discourtesy to your colleagues but may allow
others to question the credibility of the IPCC process.

We have previously circulated the attached LAGuide.pdf and are recirculating that here. We
would like to emphasize here that this applies to everyone involved in the report,
including review editors as well as authors, co-chairs, and bureau members. Please let us
know immediately at ipcc-wg1@xxxxxxxxx.xxx if you find any aspect of this document
unacceptable to you.

We cannot overstate the importance of our all paying scrupulous attention to ensuring that
IPCC draft results are not revealed in any way that could lead to their appearing in a
press venue prior to formal approval. Please redouble your efforts to avoid being
misquoted, or misidentified as representing the IPCC's draft fourth assessment report.
Best regards,

Susan Solomon, Martin Manning and Qin Dahe

Attachment Converted: "c:eudoraattachLAGuide1.pdf"
_______________________________________________ Wg1-ar4-las mailing list
Wg1-ar4-las@xxxxxxxxx.xxx http://lists.joss.ucar.edu/mailman/listinfo/wg1-ar4-las

Original Filename: 1141246541.txt | Return to the index page | Permalink | Earlier Emails | Later Emails

From: Stefan Rahmstorf <rahmstorf@xxxxxxxxx.xxx>
To: Fortunat Joos <joos@xxxxxxxxx.xxx>
Subject: Re: latest draft of 2000-year section text
Date: Wed, 01 Mar 2006 15:55:41 +0100
Cc: Jonathan Overpeck <jto@u.arizona.edu>, Tim Osborn <t.osborn@xxxxxxxxx.xxx>, Keith Briffa <k.briffa@xxxxxxxxx.xxx>, cddhr@xxxxxxxxx.xxx, Eystein Jansen <eystein.jansen@xxxxxxxxx.xxx>

Hi all,
let me add to Fortunat that I feel Keith and Tim have done a tremendous job in very thorny
terrain. And I agree with Peck - science has moved way past the "hockey stick" debate, and
it is great how our chapter shows that.
Nevertheless, we should remember that the Von Storch et al. (2004) critique was a
fundamental methodological critique that applies to *all* (or at least most) proxy
reconstructions - it is not just a Storch vs. Mann quarrel (although it is that as well, of
course). Hence it is worth mentioning their error, else this could still call the entirety
of our conclusions from that section into question.
Currently, our draft just says:

At present, the extent of any such bias in specific reconstructions is uncertain

This is true, but leaves in my view slightly too much room for interpretation - like, it
would still encompass the interpretation that the bias of all reconstructions is
desastrous, so they are all "nonsense" in Von Storch's words.
What about saying something along the lines:
"At present, the extent of any such bias in specific reconstructions is uncertain, although
probably not as large as suggested by Von Storch et al. (2004), whose work was affected by
a calibration error (Wahl, Ritson and Amman, 2006)."
Regards, Stefan
p.s. Tim: Are you convinced the more recent papers by the VS group use the correct
calibration? In those curves that are intended to show the pseudoproxies perform poorly
even when calibrated correctly, as long as you add a lot more noise, I wonder why the
pseudoproxies perform poorly even within the calibration interval, where they now should be
calibrated to properly reproduce the 20th C warming trend, and they don't?

Original Filename: 1141250377.txt | Return to the index page | Permalink | Earlier Emails | Later Emails

From: Tim Osborn <t.osborn@xxxxxxxxx.xxx>
To: Stefan Rahmstorf <rahmstorf@xxxxxxxxx.xxx>, Fortunat Joos <joos@xxxxxxxxx.xxx>
Subject: Re: latest draft of 2000-year section text
Date: Wed, 01 Mar 2006 16:59:37 +0000
Cc: Jonathan Overpeck <jto@u.arizona.edu>,Keith Briffa <k.briffa@xxxxxxxxx.xxx>, cddhr@xxxxxxxxx.xxx,Eystein Jansen <eystein.jansen@xxxxxxxxx.xxx>

<x-flowed>
Hi again Stefan,

At 14:55 01/03/2006, Stefan Rahmstorf wrote:
What about saying something along the lines:

>"At present, the extent of any such bias in specific reconstructions
>is uncertain, although probably not as large as suggested by Von
>Storch et al. (2004), whose work was affected by a calibration error
>(Wahl, Ritson and Amman, 2006)."

This sounds good and Keith is currently working your suggested
wording into the paragraph in question.

>p.s. Tim: Are you convinced the more recent papers by the VS group
>use the correct calibration? In those curves that are intended to
>show the pseudoproxies perform poorly even when calibrated
>correctly, as long as you add a lot more noise, I wonder why the
>pseudoproxies perform poorly even within the calibration interval,
>where they now should be calibrated to properly reproduce the 20th C
>warming trend, and they don't?

I am not certain, of course. And yes, there is a link between the
degree to which the trend over the calibration period is captured and
the amplitude of long-term fluctuations in the reconstruction. That
many of Burger's multitude of methods do not obtain the full warming
trend, while Mann et al. do, is certainly a concern here. But it is
also true (and I have myself analysed this one year before von Storch
et al. was published - if only I'd realised the implications I could
have had another Science paper! :-)) that correct implementation of a
regression method, keeping the trend in, can still lead to a massive
underestimation of that trend. So there's still more work to be done
on this topic!

Cheers

Tim

Dr Timothy J Osborn
Climatic Research Unit
School of Environmental Sciences, University of East Anglia
Norwich NR4 7TJ, UK

e-mail: t.osborn@xxxxxxxxx.xxx
phone: xxx xxxx xxxx
fax: xxx xxxx xxxx
web: http://www.cru.uea.ac.uk/~timo/
sunclock: http://www.cru.uea.ac.uk/~timo/sunclock.htm

</x-flowed>

Original Filename: 1141267802.txt | Return to the index page | Permalink | Earlier Emails | Later Emails

From: Keith Briffa <k.briffa@xxxxxxxxx.xxx>
To: oyvind.paasche@xxxxxxxxx.xxx
Subject: Text here for 6.6 BUT not references -help
Date: Wed Mar 1 21:50:xxx xxxx xxxx
Cc: jto@u.arizona.edu,Eystein Jansen <eystein.jansen@xxxxxxxxx.xxx>,t.m.melvin@xxxxxxxxx.xxx

Peck
here is a version you can look at. The text in blue , I suggest deleting.
please also see my message to Oyvind below
Oyvind
here is a word file that is very near to the final version for this stage, of the 6.6
section.
NOTE that we (really Tom Melvin here) have had a nightmare with trying to get references in
endnote and keeping the text as I wrote it . We need to work on finding and sorting a few
references - but in working today , Tom found endnote reordering the references being
called out in the text - actually moving them into incorrect places! To meet todays
deadline I am sending this word file version of my text , which except for possible minor
typos , is the version that I consider done (with the exception of changes Peck may wish to
make to the Regional section).
Tomorrow , could you please liaise with Tom here (see his email cc'd) to discuss how to
get the same text associated with the correct references in the way you want.Tom, as far as
I understand is mostly there - but whether his version of this text corresponds with what
it should say now - is beyond my comprehension. I have had enough of this system and I
think we should have simply used word. I am sure there will be minor formatting problems
and inconsistencies in the way cross referencing is done in what I am sending . I am also
sure that knowing which reference was meant and which is now cited will take some sorting .
Please let Tom know how you wish to proceed with this as soon as you know and he may be
able to comply. Thanks - now I am going home
Keith

--
Professor Keith Briffa,
Climatic Research Unit
University of East Anglia
Norwich, NR4 7TJ, U.K.

Phone: xxx xxxx xxxx
Fax: xxx xxxx xxxx
[1]http://www.cru.uea.ac.uk/cru/people/briffa/

References

1. http://www.cru.uea.ac.uk/cru/people/briffa/

Original Filename: 1141393414.txt | Return to the index page | Permalink | Earlier Emails | Later Emails

From: Jonathan Overpeck <jto@u.arizona.edu>
To: <oyvind.paasche@xxxxxxxxx.xxx>, Keith Briffa <k.briffa@xxxxxxxxx.xxx>, Eystein Jansen <eystein.jansen@xxxxxxxxx.xxx>
Subject: last minute changes.
Date: Fri, 3 Mar 2006 08:43:xxx xxxx xxxx

<x-flowed>
Hi Keith - pls cc everything regarding change to

Original Filename: 1141398437.txt | Return to the index page | Permalink | Earlier Emails | Later Emails

From: Jonathan Overpeck <jto@u.arizona.edu>
To: Keith Briffa <k.briffa@xxxxxxxxx.xxx>
Subject: Re: photographs and other visuals for Science
Date: Fri, 3 Mar 2006 10:07:xxx xxxx xxxx
Cc: Eystein Jansen <eystein.jansen@xxxxxxxxx.xxx>

<x-flowed>
Hi Keith - thanks. Plan sounds good, and I will use this email to
start the "do for next draft" file. Thanks, peck

>Peck
>
>we do need to say something , but as I said in an earlier message ,
>not without more consideration. We should not write something curt
>on this - ditto the Co2 possible fertilisation . In the push to do
>all this other stuff , we have had to leave it - to discuss later
>how to include an uncertainty issues bit about recent environmental
>mess ups . The D'arrigo paper is not convincing , but we have to do
>some work to show why , instead of just saying this . The divergence
>issue is NOT universal , and not unrelated to very recent period
>bias arising from processing methods . It is VERY LIKELY not the
>threshold problem D'Arrigo thinks it is. We need money here to work
>on this and losing our last application to Europe has messed us up.
>For now we can not include anything. I will work on text for the
>next iteration.
>
>At 16:05 03/03/2006, you wrote:
>>Hi Richard - this issue is one that we refer to in our key
>>uncertainty table. I believe Keith Briffa was one of the first to
>>write about it, and it is an important issue. I haven't seen R's
>>paper or results myself, but I bet Keith has. I'm cc'ing this to
>>him to see what he thinks.
>>
>>thanks, peck
>>
>>>Know anything about the "divergence problem" in tree rings? R D'arrigo
>>>talked to the NRC yesterday. I didn't get to talk to her afterward, but
>>>it looked to me that they have redrilled a bunch of the high-latitude tree
>>>rings that underlie almost all of the high-res reconstructions, and the
>>>tree rings are simply missing the post-1970s warming, with reasonably high
>>>confidence. She didn't seem too worried, but she apparently has a paper
>>>just out in JGR. It looked to me like she had pretty well killed the
>>>hockey stick in public forum--they go out and look for the most-sensitive
>>>trees at the edge of the treeline, flying over lots and lots of
>>>trees that are
>>>lesss sensitive but quite nearby, and when things get a little warmer, the
>>>most-sensitive trees aren't anymore, and so the trees miss the extreme
>>>warming of the recent times, and can't reliably be counted as catching
>>>the extreme warmth of the MWP if there was extreme warmth then.
>>>Because as far as I can tell the hockey stick really was a
>>>tree-ring
>>>record, regardless of how it was labelled as multiproxy, this looks to me
>>>to be a really big deal. And, a big deal that may bite your chapter...
>>>--Richard
>>
>>
>>--
>>Jonathan T. Overpeck
>>Director, Institute for the Study of Planet Earth
>>Professor, Department of Geosciences
>>Professor, Department of Atmospheric Sciences
>>
>>Mail and Fedex Address:
>>
>>Institute for the Study of Planet Earth
>>715 N. Park Ave. 2nd Floor
>>University of Arizona
>>Tucson, AZ 85721
>>direct tel: xxx xxxx xxxx
>>fax: xxx xxxx xxxx
>>http://www.geo.arizona.edu/
>>http://www.ispe.arizona.edu/
>
>--
>Professor Keith Briffa,
>Climatic Research Unit
>University of East Anglia
>Norwich, NR4 7TJ, U.K.
>
>Phone: xxx xxxx xxxx
>Fax: xxx xxxx xxxx
>
>http://www.cru.uea.ac.uk/cru/people/briffa/

--
Jonathan T. Overpeck
Director, Institute for the Study of Planet Earth
Professor, Department of Geosciences
Professor, Department of Atmospheric Sciences

Mail and Fedex Address:

Institute for the Study of Planet Earth
715 N. Park Ave. 2nd Floor
University of Arizona
Tucson, AZ 85721
direct tel: xxx xxxx xxxx
fax: xxx xxxx xxxx
http://www.geo.arizona.edu/
http://www.ispe.arizona.edu/
</x-flowed>

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From: "Tim Osborn" <t.osborn@xxxxxxxxx.xxx>
To: k.briffa@xxxxxxxxx.xxx
Subject: [Fwd: Re: data request to SCIENCE for 1120514]
Date: Tue, 7 Mar 2006 08:22:xxx xxxx xxxx(GMT)
Reply-to: t.osborn@xxxxxxxxx.xxx
Cc: t.osborn@xxxxxxxxx.xxx

Keith - see below. I bet it won't be the end of the episode! - Tim

---------------------------- Original Message ----------------------------
Subject: Re: data request to SCIENCE for 1120514
From: "Jesse Smith" <hjsmith@xxxxxxxxx.xxx>
Date: Mon, March 6, 2006 8:03 pm
To: t.osborn@xxxxxxxxx.xxx
--------------------------------------------------------------------------

Dear Dr. Osborn,

Thank you for your clear and careful response to the requests made by
Dr. McIntyre, which we forwarded to you: it was quite satisfactory, we
believe, and will greatly help Brooks (Hanson) in crafting his reply to
Dr. McIntyre. I hope that this will be the end of this episode, but if
it is not, we will be in touch again.

Best regards,

Jesse Smith

=======================
Dr. Jesse Smith
Senior Editor
----------------------------------------------
Science
1200 New York Avenue, NW
Washington, DC 20005
USA
----------------------------------------------
(2xxx xxxx xxxx
(2xxx xxxx xxxx(FAX)
hjsmith@xxxxxxxxx.xxx
=======================

>>> Tim Osborn <t.osborn@xxxxxxxxx.xxx> 3/3/2006 11:22:17 AM >>>

Dear Jesse Smith and Brooks Hanson,

thank you for your patience while waiting for our reply. Before
responding to the specific data requests, we would like to say that
it is our view that we should provide sufficient data to enable all
the main elements of our analysis to be checked, but that we are not
obliged to provide the data that would enable the research reported
in other papers to be checked, even if we cite those other papers or
use results reported in those other papers. You will see how this
view has determined our response to some of the requests.

Now to the requests themselves, numbered according to the numbering
system of Steve McIntyre's email.

(1) As you know, we provided (in advance of publication) the 14
smoothed and normalised proxy records to WDC-Paleo that enable the
main parts of our analysis to be replicated. The only part of our
analysis for which the unsmoothed data are required is to calculate
the correlations against temperature that we reported for some of the
series (not those that had already been reported by Mann and Jones,
as indicated in our Table S1). These unsmoothed data for all 14
series are now also archived at WDC-Paleo, which will enable those
correlations that we reported in Table S1 to be checked. These
unsmoothed data were archived on Thursday 23rd February, in response
to a request by a different colleague. This should cover this request
in full.

(2) Our Table S1 provides the full citation to the source of our
data, funnily enough given in the column labelled "Data
source". Some of these may or may not have publicly archived their
data, but our WDC-Paleo entry now contains the series that we were
originally provided with (i.e., the unsmoothed data that we refer to
in item (1) above). The "Orig source" column in our table was our
effort to ensure that original work on collecting/processing these
data is acknowledged, because it is important for us to acknowledge
that work even when we obtained the data from a secondary study. We
did not intend to imply that the data that we had used would match
the data in these original sources, because various different
versions might exist (due, e.g., to different methods of processing
the data, or due to updated measurements, etc.). That is why we made
the source of our data clear.

(a-c) We have not yet had time to double check the ITRDB citations
that we provided for these three records, but we will do so as soon
as we have time. Our data source was in fact Esper et al. (2002) and
this is correct, so the concern over the accuracy of these ITRDB
citations does not limit the ability for others to check our work.

(d-f) The original studies that we cite are definitely correct for
these two records. We have provided sufficient data for our analysis
of these records to be checked. We have not provided extra data to
enable other people's studies to be checked, nor do we feel obliged to
do so.

(g) These series from Esper et al. (2002) were considered by us and
then rejected. As we understand it, Esper et al. have made available
their site RCS records and therefore these four records could be
obtained from Esper et al. If this is not the case, we could provide
these four rejected series.

(3) D'Arrigo et al. (2006) do *not* report directly opposite findings
in respect to the correlations we obtain for Jaemtland and
Boreal/Upperwright. Neither paper reports any correlations involving
these series versus temperature. Both papers list more than one
reason why series might be rejected. For example, our reasons were
"We removed series from (S1) that did not correlate positively with
their local annual or summer temperatures (Table S1), or which did
not extend into the period with instrumental temperature to allow a
correlation to be calculated." The latter is our reason for
excluding Jaemtland, not the former: the Jaemtland series that we
obtained from Esper et al. (2002) has no data after 1827 and so no
correlation was calculated. The Jaemtland series used by D'Arrigo et
al. continues through to 1978 due to the inclusion of additional
data. Similarly, D'Arrigo et al. list a number of reasons for
excluding series, but they do not state which one(s) were used to
exclude Boreal and Upperwright, though in fact none disagreed with
our criteria anyway!

We have not separately stored the temperature time series used to
obtain the correlations reported in our Table S1 and to do so
requires some changes to our program, which we have not done because
there does not appear to be a need to do so (given our explanation
above of the situation regarding our paper versus D'Arrigo et al.,
2006).

Because Steve McIntyre has explicitly stated that he is unable to
verify our results for the Boreal/Upperwright case, we have extracted
the temperatures we used for that case only and attach them here as a
text file. We hope that he can use them to reassure himself about
the correlations that we obtained.

(4)
(a) We explicitly state that we did not use the Esper et al. (2002)
Jasper series, so there is no expectation that they should be
identical. Esper et al. (2002) have, we believe, made their version
available and we have made available the series that we used via
WDC-Paleo.

(b) Similarly, we explicitly state that we did not used the Esper et
al. (2002) Tornetrask series and data are available as for (a).

(c) We are not obliged to confirm anything that Esper et al. (2002)
did.

(5) This request is not relevant to our paper, as discussed at the
start of this email.

(6) Same as (5).

We hope that we have dealt with these requests to a more than
satisfactory extent, but please let us know if you feel that we should
do more.

Best regards

Tim Osborn and Keith Briffa

At 19:30 23/02/2006, you wrote:
>Dear Dr. Osborn,
>
>We have just received an email from Steve McIntyre (pasted below),
>with a long and very specific list of alleged deficiencies in the
>availability of data by which to evaluate your recent paper, "The
>Spatial Extent of 20th-Century Warmth in the Context of the Past
>1200 Years," and others. Wishing to deal with this issue in a
>conscientious and reasonable way, we are passing the email along to
>you as a request for data, without taking a position on the validity
>of any particular point. We would like to have your confidential
>response to this request, keeping in mind the stated policy of
>SCIENCE that "Any reasonable request for materials, methods, or data
>necessary to verify the conclusions of the experiments reported must
>be honored." Please return your response by email directly to me,
>and CC: Brooks Hanson, our Deputy Editor
>(<mailto:bhanson@xxxxxxxxx.xxx>bhanson@xxxxxxxxx.xxx). We appreciate your
>cooperation, as well as the time and effort that a reply may
>take. Feel free to contact me if you have any questions about this
issue.
>
>
>Sincerely,
>
>Jesse Smith
>
>*******START OF EMAIL FROM S. MCINTYRE*********
>Dear Dr Hanson,
>
>Thank you for your prompt response to my letter in respect to Osborn
>and Briffa [2006], Esper et al [2002] and Thompson et al [1989;
>1997]. I appreciate your efforts in this and realize that you are
>frustrated at being criticized. However, if you reflect on the
>matter, I'm sure that you will agree that the problem stems entirely
>from the original authors failing to comply with Science's data
>archiving policy.
>
>It will come as no surprise to you that I do not believe that the
>additional data, useful as it is, comes anywhere near discharging
>Science's obligations under its data policies for reasons that I
>will set out in detail below. I will discuss the shortfalls in
>connection with what I understand to be one of Science's governing
>policies
><http://www.sciencemag.org/feature/contribinfo/prep/gen_info.dtl#datadep>http://www.sciencemag.org/feature/contribinfo/prep/gen_info.dtl#datadep)

>:
>
>Science supports the efforts of databases that aggregate published
>data for the use of the scientific community. Therefore, before
>publication, large data sets . must be deposited in an approved
>database and an accession number provided for inclusion in the
published paper.
>
>Since the issue pertains to how Science discharges its policies, it
>is my position that you, rather than the original authors, are the
>appropriate arbiter of that. (Additionally, the authors have refused
>all requests in the past and I see no reason why their behavior
>would now differ.)
>
>Status of Each Request:
>
> 1. Digital versions of all 14 series as used in their
> final compilations;
>
>I have inspected the archive at
><ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/osborn2006/osborn2006.txt>ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/osborn2006/osborn2006.txt,

>to which you directed me. This consists of smoothed (and re-scaled)
>versions of the 14 series and is relevant to the request, but does
>not satisfy it. The authors specifically discuss correlations of
>these series to temperature, which requires consideration of the
>pre-smoothed series. Accordingly, I re-iterate my original request
>for digital versions of the 14 series.
>
>2. For each of the tree ring sites analysed (both the 11
>retained and Esper site not used, including Gotland, Jaemtland,
>Mackenzie Mts and Zhaschiviersk), an exact data citation to a public
>archive (e.g. WDCP) for the data set used; or, in the alternative,
>an archive of the data set at the Science website. In cases, where
>the publicly archive dataset for a site is related to but different
>from the version used by Osborn and Briffa, please archive the data
>set as used.
>
>I was able to reasonably reconcile the smoothed series to original
>sources in public archives and accordingly have no issue with data
>provenance for the following Osborn and Briffa series: the Mann PC1
>(#1); #5 Chesapeake; - #6 - Fisher's Greenland O18 stack; #7 -
>Netherlands documentary; #14 - Yang's China composite (although
>there are problems in the Thompson series used in this composite).
>For other users less familiar with nuances of series versions, I
>recommend that the SI be modified to provide accurate data citations
>for these 5 series.
>
>The problems mostly pertain to tree ring data, which make up the
>other 9 series. In three cases, Osborn and Briffa provided data
>citations for sites in public archives (#4 - Quebec- cana169; #8 -
>Tirol - germ21; #11 - Mangazeja - russ067, russ068). In each of
>these 3 cases, the Esper version reconciles to the Osborn version
>(up to re-scaling). However, they do not reconcile to the original
data sets.
>
>axxx xxxx xxxxthe dataset germ21, cited by Osborn-Briffa for series #8-
>Tirol, has values from 1466 to 1837, while the archived version goes
>from 1324 to 1975. Obviously the data set has not been cited
>accurately or is incomplete.
>
>bxxx xxxx xxxxthe series cana169 goes from 1352 to 1989, while the Osborn
>version (#4 - Quebec) goes from 1352 to 1947. Again, it appears
>that the data set has not been cited accurately or is incomplete.
>Additionally, while I have been able to substantially replicate the
>features of other RCS chronologies, my efforts to reproduce the
>archived result from cana169 lead to a series with a significantly
>different shape.
>
>cxxx xxxx xxxxone of the two cited data sets (russ067) does not contain
>measurements at WDCP. However, the versions "mangazla" and
>"mangazpc" in the Schweingruber section of WDCP appear to have the
>data for russ067 and russ068. However, these data sets only yield
>values from 1246 to 1969, while the archived Osborn version (#11 -
>Mangazeja) goes from 1246 to 1990. Some additional data must exist
>somewhere, but has not been archived at WDCP to date.
>
>Two sites (#9 - Tornetrask; #13 - Mongolia) have WDCP measurement
>archives (swed019; mong003 respectively), but there are
>inconsistencies between the data as archived and the length of the
>Osborn and Briffa versions.
>
>dxxx xxxx xxxxthe WDCP archive for Tornetrask ends in 1990, which is
>inconsistent with the Osborn version which ends in 1993. This
>indicates that the data sets are not the same.
>
>exxx xxxx xxxxsimilarly, the WDCP archive for Sol Dav, Mongolia begins in
>900, while the Osborn version begins in 800.
>
>For the following 5 sites, no archive of the measurements exists at
>all - a direct breach of Science's archiving policy:
>
>fxxx xxxx xxxxJasper/Icefields, Boreal, Upper Wright, Taimyr, Yamal,
>
>Accordingly, I re-iterate my request that the measurement data
>consistent with the archived site chronologies be archived for each
>of the above items 2(a)- 2(f), as well as corresponding information
>for the following 4 sites considered in Osborn and Briffa:
>
>gxxx xxxx xxxxGotland, Jaemtland, Mackenzie; Zhaschiviersk
>
>3. Digital versions of the specific gridcell temperature series
>used in each of the reported temperature correlations together with
>version date.
>
>As noted in my previous request, D'Arrigo et al [2006] have reported
>directly opposite findings in respect to the correlation between
>their RCS chronology and gridcell temperature for: Jaemtland and the
>two foxtail series. I have specifically been unable to verify their
>claim in respect to bristlecones. Accordingly, I re-iterate the
>request for the digital versions of the temperature data used in
>these calculations. (In connection with a similar request, Nature
>required Mann et al. to archive the exact temperature data used in
MBH98.)
>
>4. Exact data citations to a public archive for all datasets
>used, or, if such do not exist, an archive of the data set at the
>Science website.
>
>While most Osborn versions match Esper versions up to re-scaling,
>they differ in three cases, and a separate Esper version is required
>in two of them:
>
>axxx xxxx xxxxthe Esper version for the Jasper data is different than the
>Osborn and Briffa version (as noted in Osborn and Briffa) and both
>data sets need to be made available;
>
>bxxx xxxx xxxxsimilarly, there are differences between the version of the
>Tornetrask series archived by Esper and the one archived by Osborn,
>again requiring examination of both data sets;
>
>cxxx xxxx xxxxthe Polar Urals version of Esper differs from the Yamal
>version of Briffa. It is possible that the Esper version used a
>combination of data sets russ021 and russ176 (if so, would you
>please confirm this.)
>
>5. A clear and operational definition distinguishing "linear"
>and "nonlinear" trees, preferably with source code showing any
>differences in methodology.
>
>While the provision of site chronologies for 13 Esper sites is
>appreciated, one site (Mongolia) was unaccountably omitted. The
>corresponding information is requested.
>
>While the provision of the site chronologies was interesting and
>appreciated, according to my reading of Esper et al [2002], these
>site chronologies were not used in the calculations in the article,
>which distinguished between "linear" and "nonlinear". No operational
>definition is provided. combined with the unavailability of the bulk
>of the data, the calculations of "linear" and "nonlinear"
>chronologies cannot be replicated even from the recent information
>regarding Esper et al [2002] and this remains unresolved.
>
>6. Thompson provides a complete archive of both Dunde and
>Guliya ice cores, including both isotope and chemical data.
>
>While I appreciate that Thompson has provided sample information on
>(only) 2 Kilimanjaro cores, he did not provide the requested
>accompanying chemical information necessary for their
>interpretation. The Kilimanjaro data is obviously of little help
>with the Dunde and Guliya data.
>
>The U.S. Global Change Research Program required archiving of data
>commencing in 1991 and the World Data Center for Paleoclimatology
>has been in existence since then and has been online since 1994.
>Accordingly there was an adequate facility for the archiving of the
>Guliya core when it was published in 1997.
>
>I realize that the Dunde core was published in 1989, at a time when
>your present archiving policies were not in effect. However,
>Thompson has published versions of this series in other journals
>which are inconsistent with the version published in Science. I
>cannot imagine that you are content with such a situation. Even if
>you did not have policies at the time, I am sure that you can give a
>very firm request to Thompson and I find it difficult to believe
>that Thompson would refuse a direct request from Science to provide
>this data. If he has refused a direct request, then that too is
>relevant information, upon which I would appreciate confirmation.
>
>Again, I apologize for putting you in the middle of this and for the
>public nature of the exchange. However, some of this has been going
>on far too long with minimal results, leaving no alternative.
>However, I assure you that I will be equally public in commending
>you if and when you resolve matters. In my opinion, you should
>simply do the following:
>
>xxx xxxx xxxx send a copy of your data archiving policy to each
>of the authors: Osborn-Briffa; Esper et al. and Thompson;
>
>xxx xxxx xxxx tell Osborn-Briffa and Esper et al. that you
>expect them to comply with the policy which was in effect at the
>time of publication or else you will retract the article.
>
>xxx xxxx xxxx tell Thompson that, if he wants to publish at
>Science in the future, he should immediately clean up his archive
>for the earlier articles.
>
>Obviously there has been some inadequate housekeeping in the past. I
>can understand this and my concern is not with the past. My concern
>is with the present. You have an opportunity to remedy the situation
>now and no one will criticize Science for ensuring that paleoclimate
>authors meet Science's data archiving policies. On the other hand,
>you will be justly criticized both by me and others if you don't do
so.
>
>
>
>Regards,
>
>Stephen McIntyre
>
>********END OF EMAIL FROM S. MCINTYRE**********
>*******************************************
>
>=======================
>Dr. Jesse Smith
>Senior Editor
>----------------------------------------------
>Science
>1200 New York Avenue, NW
>Washington, DC 20005
>USA
>----------------------------------------------
>(2xxx xxxx xxxx
>(2xxx xxxx xxxx(FAX)
><mailto:hjsmith@xxxxxxxxx.xxx>hjsmith@xxxxxxxxx.xxx
>=======================

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From: Jonathan Overpeck <jto@u.arizona.edu>
To: cddhr@xxxxxxxxx.xxx, Eystein Jansen <eystein.jansen@xxxxxxxxx.xxx>, rahmstorf@xxxxxxxxx.xxx, Bette Otto-Bleisner <ottobli@xxxxxxxxx.xxx>, joos <joos@xxxxxxxxx.xxx>, Dominique Raynaud <raynaud@xxxxxxxxx.xxx>, "James Zachos" <jzachos@xxxxxxxxx.xxx>, Valerie Masson-Delmotte <Valerie.Masson@xxxxxxxxx.xxx>, Keith Briffa <k.briffa@xxxxxxxxx.xxx>, t.osborn@xxxxxxxxx.xxx
Subject: Fwd: Re: [Wg1-ar4-ch06] Chapter 6 glossary edited version
Date: Tue, 7 Mar 2006 12:02:xxx xxxx xxxx

Hi folks - seems the listserv is down again. Please take a look at the attached draft chap
6 glossary and send comments to me and David Rind today if you have any (Jim Z - hope you
can look at the way we've butchered the preQ defns). Eystein and I would like to send to
TSU tonight if we can.

Thanks, Peck

Date: Tue, 7 Mar 2006 11:45:xxx xxxx xxxx
To: David Rind <drind@xxxxxxxxx.xxx>
From: Jonathan Overpeck <jto@u.arizona.edu>
Subject: Re: [Wg1-ar4-ch06] Chapter 6 glossary edited version
Cc:
Bcc: wg1-ar4-ch06@xxxxxxxxx.xxx, fons_baede@xxxxxxxxx.xxx
X-Attachments: :Macintosh HD:329718:Chapter 6 glossaryJTO.doc:

Hi David (and those who have contributed) - thanks!
I've attached a revised version, with my edited sections highlighted in yellow. I've
tried to update some definitions to be more accurate (agree w/ Stefan, by the way,
regarding D/O events), and also to standardize mention of time intervals.
Also, I don't think we want to cite the sources you have cited, since these were only
the sources used to get going. I think many of the definitions are updated significantly
by our team.
If you get any other feedback today, great. Please forward me and Eystein your final
version at the end of the day, and we'll send to the TSU (and Fons). If you get no
additional input, just let us know and we can send in the attached version w/ the yellow
shading removed.

Thanks again, Peck

--

Jonathan T. Overpeck
Director, Institute for the Study of Planet Earth
Professor, Department of Geosciences
Professor, Department of Atmospheric Sciences
Mail and Fedex Address:
Institute for the Study of Planet Earth
715 N. Park Ave. 2nd Floor
University of Arizona
Tucson, AZ 85721
direct tel: xxx xxxx xxxx
fax: xxx xxxx xxxx
http://www.geo.arizona.edu/
http://www.ispe.arizona.edu/

--

Jonathan T. Overpeck
Director, Institute for the Study of Planet Earth
Professor, Department of Geosciences
Professor, Department of Atmospheric Sciences
Mail and Fedex Address:
Institute for the Study of Planet Earth
715 N. Park Ave. 2nd Floor
University of Arizona
Tucson, AZ 85721
direct tel: xxx xxxx xxxx
fax: xxx xxxx xxxx
http://www.geo.arizona.edu/
http://www.ispe.arizona.edu/

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From: Jonathan Overpeck <jto@u.arizona.edu>
To: Keith Briffa <k.briffa@xxxxxxxxx.xxx>
Subject: Fwd: divergence
Date: Wed, 8 Mar 2006 15:18:xxx xxxx xxxx
Cc: ralley@xxxxxxxxx.xxx, Eystein Jansen <eystein.jansen@xxxxxxxxx.xxx>, Bette Otto-Bleisner <ottobli@xxxxxxxxx.xxx>, joos <joos@xxxxxxxxx.xxx>, t.osborn@xxxxxxxxx.xxx, "Ricardo Villalba" <ricardo@xxxxxxxxx.xxx>

<x-flowed>
Hi gang - Richard is raising important issues, and Keith is going to
respond in some detail on Friday when he gets back. I am cc'ing this
to a broader group of IPCC Chap 6 folks so that we make sure we (chap
6) deal with the issues correctly. I'm hoping that Keith will cc to
us all, and we'll go from there.

For those just in on the issue raised by Richard. There is a paper
written by Rosanne D'Arrigo that apparently casts serious doubt on
the ability of tree ring data to reconstruct the full range of past
temperature change - particularly temperatures above mid-20th century
levels. Chap 6 obviously has to deal with this more in the next
draft, so Eystein and I would like to get on top of it starting this
week.

Keith or Richard - do you have a copy of this paper? Is it accepted?

Thanks, Peck

>X-Sieve: CMU Sieve 2.2
>Date: Wed, 8 Mar 2006 11:55:xxx xxxx xxxx(EST)
>From: <ralley@xxxxxxxxx.xxx>
>To: jto@u.arizona.edu
>Cc: k.briffa@xxxxxxxxx.xxx
>Subject: divergence
>
>Peck--Thanks. The big issue may be that you don't just have to convince me
>now; if the NRC committee comes out as being strongly negative on the
>hockey stick owing to RD'A's talk, then the divergence between IPCC and NRC
>will be a big deal in the future regardless. The NRC committee is accepting
>comments now (I don't know for how long)... As I noted, my observations
>of the NRC committee members suggest rather strongly to me that they now
>have serious doubts about tree-rings as paleothermometers (and I do,
>too...at least until someone shows me why this divergence problem really
>doesn't matter). --Richard

--
Jonathan T. Overpeck
Director, Institute for the Study of Planet Earth
Professor, Department of Geosciences
Professor, Department of Atmospheric Sciences

Mail and Fedex Address:

Institute for the Study of Planet Earth
715 N. Park Ave. 2nd Floor
University of Arizona
Tucson, AZ 85721
direct tel: xxx xxxx xxxx
fax: xxx xxxx xxxx
http://www.geo.arizona.edu/
http://www.ispe.arizona.edu/
</x-flowed>

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From: Phil Jones <p.jones@xxxxxxxxx.xxx>
To: Eystein Jansen <Eystein.Jansen@xxxxxxxxx.xxx>, Jonathan Overpeck <jto@u.arizona.edu>
Subject: Re: Climate Audit
Date: Thu, 09 Mar 2006 13:48:31 +0000
Cc: Keith Briffa <k.briffa@xxxxxxxxx.xxx>

<x-flowed>

Dear All,
A lot of good points raised by the horizontal Eystein. Keith is
hoping to do something on the recent tree growth issue.

What this sad crowd (nice words - I'll use the phrase again) don't
realise is that the satellite data now agree with the surface. This is
said in Ch 3 and will come home more forcefully once the CCSP
report on vertical temperature trends comes out. This should be
April or May according to Tom Karl who is overseeing it all. I say
should as it apparently has to be approved by the White House!
Peck will know why this is and the expertise of the people doing
the approval!

I can say for certain (100% - not any probable word that IPCC
would use) is that the surface temperature data are correct.

McIntyre is determined and the blog does influence people, unfortuately
the media. As you say as issues are partially closed, they will move on
to others.

Cheers
Phil

At 12:50 09/03/2006, Eystein Jansen wrote:
>Hi Phil, thanks for the greetings. The back is status quo-like, so today
>the neurosurgeons concluded I need a surgery to take care of the hernia
>that creates the pains. Will take place in a week or two, and I will be
>out of work for a month afterwards, but should be up and going in good
>time for Wengen and for LA4.
>
>One side effect of being stranded and in horisontal working mode is more
>time to browse the net, thus I have monitored the Climate Audit page.
>Looking at the discussions after the NAS panel meeting we should expect
>focus now to be sidetracked from PC-analyses and over to the issue of bad
>proxies and divergence from temperature in the last 50 years. Thus this
>last aspect needs to be tackled more candidly in AR4 than in the SOD, and
>we need to discuss how to do this, soon. The Key expert here is Keith and
>I guess we should be able to assess the situation based on his and
>D

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From: <ralley@xxxxxxxxx.xxx>
To: eystein.jansen@xxxxxxxxx.xxx, joos@xxxxxxxxx.xxx, jto@u.arizona.edu, k.briffa@xxxxxxxxx.xxx, ottobli@xxxxxxxxx.xxx, p.jones@xxxxxxxxx.xxx, ricardo@xxxxxxxxx.xxx
Subject: NRC and IPCC millennial temperatures
Date: Sat, 11 Mar 2006 15:27:xxx xxxx xxxx(EST)
Cc: mmanning@xxxxxxxxx.xxx, ssolomon@xxxxxxxxx.xxx

Friends in the IPCC WG1 AR4--

My impression is that, for good reasons, the US NRC panel looking at
the record of temperatures over the last millennium or two is not going
to strongly endorse the ability of proxies to detect warming above the level
of a millennium ago, and that a careful re-examination of the
Chapter 6 wording and its representation in the TS and SPM would
be wise. Some of you have seen some of the discussion that follows,
in some of the rapid-fire emails over the last day or two, but I'd like
to clarify a little.

Please note that I am NOT on the NRC committee, do not speak for them, and
have no "inside" knowledge of what they are doing. I was asked to
testify to them, and I heard remarks from some other speakers and questions
from the committee in public forum. I did NOT represent the IPCC to the
committee, either; I stated that although I was proud to be participating
with the IPCC, I absolutely was not speaking for, representing, or presaging
anything in the IPCC. (I was, however, favorably quite impressed with the NRC
committee and their efforts.) Someone else may have a different impression of
what went on; this is mine.

Among the presentations, involving borehole temperatures, corals, glaciers and
ice cores, and historical records, that which to me seemed to interest
the committee most was from Rosanne d'Arrigo, who reported (among many other
things) on a just-published study in which northern tree-ring sites were
revisited and updated, and in which many of those sites failed to track the
recent warming documented instrumentally. She did not make a big deal out
of this, but several of the questions afterward from the committee focused on
this "divergence" problem. (And to note, Rosanne did not discover the
divergence problem, which has been around and discussed for a while; her
testimony, including the recent large effort to update some tree-ring records,
stirred interest from some committee members.)

I would also note that one of the committee members was asking each presenter
whether the presenter believed that temperatures could be reconstructed for
1000 years ago within 0.5 C, and that the presenters were answering with some
qualified version of "no".

My guess is that the NRC committee will put these things together, find some
papers on ozone damage and CO2 fertilization, consider Rosanne's statement
that the preferred temperature-sensitive trees are rare and in restricted places
(and thus that a prolonged warming could easily move those trees out of the
sensitive band), and conclude that tree-ring reconstructions include larger
errors than are returned by any of the formal statistics from calibration
or aggregation of records, and thus that there is less confidence than
previously believed in the relative warmth of recent versus Medieval times.
I also consider it possible that they will point out the difficulty of using
a composite temperature history consisting of proxy and instrumental data if
some of the proxy data do not track the more-recent part of the instrumental
data.

The IPCC must be the IPCC, not the NRC. But, if the IPCC and NRC look very
different, there will be much comment, and we will have to be very sure.
More importantly, I believe that real issues are raised here, and that
better discussion of this should be included in chapter 6, and probably
brought forward at least into the TS. I know I'm not in chapter 6, I know
I'm not a tree-ring expert, and I know I'm sticking my nose in where it might
not belong or be welcome. But the flurry of emails in the last couple of days
has not convinced me that this one can be ignored; indeed, I am more convinced
that there exist issues that the IPCC must discuss more thoroughly.

My impression of the status (and my thoughts about what chapter 6 might say)
from a whole lot of quick reading, your emails, and the testimony and
questions I heard, is along the lines of:

--> The TAR highlighted a temperature history composited from multi-proxy
paleoclimatic indicators plus the instrumental record, showing anomalous
recent warmth, with the recent warmth emerging well above the 95% confidence
interval for the last millennium.

--> The multi-proxy paleoclimatic indicators reflect tree-ring results more
than any other source.

--> Tree-ring records are responsive to many factors, and great care and
effort go into isolating the temperature signal from other signals.

--> Tree-ring data, in common with essentially all paleoclimatic data, are not
collected in a continually updated "operational" fashion analogous to that used
for meteorological data, so the data sets end at different times; data used
in the multi-proxy reconstructions cited in the TAR ended between the 1990s
and the 1940s. This difficulty motivated the need to include instrumental
as well as proxy data in the reconstructions.

--> In those data, there was some suggestion of non-temperature influences
on the tree-ring reconstructions; in particular, some of the
most-recent records did not record the full amplitude of the instrumental
warming. This has come to be known as the "divergence" issue.

--> Much research has been conducted since the TAR, and additional evidence
of divergence has emerged in some records, causing some aggregated
reconstructions from proxy records to show less warming than does the
instrumental record.

--> There are many hypotheses for non-temperature influences on tree-ring
records, including: (i) recent damage (as by ozone); (ii) recent fertilization
(as by CO2); and (iii) decreasing sensitivity of tree-ring growth to
temperature with increasing temperature (once it's warm enough, the trees are
primarily responsive to other things). The nature of these and their timing
relative to the interval in which tree-ring data were calibrated to
instrumental records would control the effects on climate reconstructions.
In general: (i) would mean that recent warmth is underestimated but warmth
from a millennium ago is not; (ii) would mean that recent warmth is
overestimated but warmth from a millennium ago is not; and (iii) would mean
that both recent warmth and warmth from a millennium ago are underestimated.

--> Various arguments have been advanced to support (i), (ii), or (iii),
with many workers in the field favoring (i). Nonetheless, further
characterizing recent non-temperature influences on tree-ring growth
remains an open research question, and no broad consensus has emerged on
(i), (ii), (iii), or something else.

--> These considerations do not affect the conclusion that recent warmth
is anomalous over the last few centuries; the strong correlations of the
proxy data with temperature over the instrumental record, and the strong
tree-ring signals, are evident.

--> These considerations do not affect the best estimate that recent warmth
is greater than that of a millennium ago; the central estimate from proxy data
of latter-twentieth-century warmth is still above that of a millennium ago, with
greater spatial conherence recently in the signal.

--> These considerations do somewhat affect the confidence that can be attached
to the best estimate of recent warmth versus that of a millennium ago. If the
paleoclimatic data could be confidently be interpreted as paleotemperatures,
then joining the paleoclimatic and instrumental records would be appropriate,
and the recent warmth would clearly be anomalous over the last millennium and
beyond. By demonstrating that some tree-ring series chosen for temperature
sensitivity are not fully reflecting temperature changes, the divergence issue
widens the error bars and so reduces confidence in the comparison between
recent and earlier warmth.

--Richard

Richard B. Alley
Evan Pugh Professor
Department of Geosciences, and Earth and Environmental Systems Institute
The Pennsylvania State University
517 Deike Building
University Park, PA 16802, USA
ph. xxx xxxx xxxx
fax xxx xxxx xxxx
email rba6@xxxxxxxxx.xxx

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From: Jonathan Overpeck <jto@u.arizona.edu>
To: drdendro@xxxxxxxxx.xxx, Keith Briffa <k.briffa@xxxxxxxxx.xxx>, Eystein Jansen <eystein.jansen@xxxxxxxxx.xxx>
Subject: NRC study
Date: Mon, 13 Mar 2006 16:29:xxx xxxx xxxx

<x-flowed>
Hi Ed and Keith - I hate to say it, but Richard's take on the
political aspects of the NRC vs. IPCC reports seem worth some extra
effort. Since you were both invited to speak with the NRC committee,
I would suggest that you both (together or separately) submit formal
comments asap. I don't know when the comment period starts or ends,
but I'm guessing you have to work fast. I'm also thinking that you
two might want to get out a peer-reviewed paper on the topic really
soon too. I worry that the hole will continue to deepen for
dendroclimate if you two don't act to clarify what we know/don't
know, and when it is safe (and why) to use dendroclimate data to
address the issue of long-term variation in temperature.

Please don't construe my suggestions or comments as pro/con dendro,
but rather just as someone who wants the truth - whatever it is - to
be communicated clearly, and as best we know it. But, I do think that
if Richard is suspect, dendro has a real problem. He doesn't have a
personal bias in this, and is clearly trying harder than most to
understand what's really going on with climate and the proxies.

Effort now might save time later.

Also, are you both going to be at the Swiss mtg in June? We really
have to get this all ironed out better before the next (last) draft
of the IPCC AR4.

Thanks, Peck
--
Jonathan T. Overpeck
Director, Institute for the Study of Planet Earth
Professor, Department of Geosciences
Professor, Department of Atmospheric Sciences

Mail and Fedex Address:

Institute for the Study of Planet Earth
715 N. Park Ave. 2nd Floor
University of Arizona
Tucson, AZ 85721
direct tel: xxx xxxx xxxx
fax: xxx xxxx xxxx
http://www.geo.arizona.edu/
http://www.ispe.arizona.edu/
</x-flowed>

Original Filename: 1142314357.txt | Return to the index page | Permalink | Earlier Emails | Later Emails

From: Jonathan Overpeck <jto@u.arizona.edu>
To: edwardcook <drdendro@xxxxxxxxx.xxx>
Subject: Re: NRC study
Date: Tue, 14 Mar 2006 00:32:xxx xxxx xxxx
Cc: Keith Briffa <k.briffa@xxxxxxxxx.xxx>, Eystein Jansen <eystein.jansen@xxxxxxxxx.xxx>

Hi Ed - thanks for trying to fit something in quick for the NRC group. I'm not sure about
Richard's full motives, but I think he has his heart in the right place - that the NRC
Committee might have gotten the impression he did, and this will be reflected in their
report, perhaps in a way that is even less satisfactory to you and Keith. And, this report
will likely have enormous political potential. It needs to get things as right as possible
from the start. So... time well spent on the part of you and Keith. Thanks much, peck

Hi Peck,

Being in Bangkok, on to PACLIM, on to CONCORD in Mendoza, back to Bangkok, and back to
NY on May 1 makes it difficult for me to do much, but I will do what I can to salvage a
bad situation. The longish emails I sent out to you all contain much of what I would
write. The main point to make, one that Richard seems to be totally oblivious to, is
that there is no evidence for loss of sensitivity prior to the 20th century in a
large-scale NH sense like that seen in the 20th century. On the other hand, there is
evidence that there was not a loss of sensitivity in a large-scale NH sense in my QSR
paper (Fig. 6). I acknowledge the weakness in the data prior to about 1200, but even so
the regional comparisons only show divergence between north and south in the 20th
century, with none indicated during the putative MWP. So why is Richard and the NRC
panel apparently stating without evidence that divergence probably is a problem in the
past and, therefore, tree rings cannot be trusted to reconstruct past temperatures? It
is honestly unscientific when the only evidence that I have seen refutes that premise,
and it plays unfairly into McIntyre's hand. I almost admit to being very irritated that
Richard should anoint himself as the arbitrator of this debate. He knows nothing
substantive about tree rings. In that sense, he is just like Ray Bradley.

Cheers,

Ed

On Mar 14, 2006, at 6:29 AM, Jonathan Overpeck wrote:

Hi Ed and Keith - I hate to say it, but Richard's take on the political aspects of the
NRC vs. IPCC reports seem worth some extra effort. Since you were both invited to speak
with the NRC committee, I would suggest that you both (together or separately) submit
formal comments asap. I don't know when the comment period starts or ends, but I'm
guessing you have to work fast. I'm also thinking that you two might want to get out a
peer-reviewed paper on the topic really soon too. I worry that the hole will continue to
deepen for dendroclimate if you two don't act to clarify what we know/don't know, and
when it is safe (and why) to use dendroclimate data to address the issue of long-term
variation in temperature.

Please don't construe my suggestions or comments as pro/con dendro, but rather just as
someone who wants the truth - whatever it is - to be communicated clearly, and as best
we know it. But, I do think that if Richard is suspect, dendro has a real problem. He
doesn't have a personal bias in this, and is clearly trying harder than most to
understand what's really going on with climate and the proxies.

Effort now might save time later.

Also, are you both going to be at the Swiss mtg in June? We really have to get this all
ironed out better before the next (last) draft of the IPCC AR4.

Thanks, Peck

--

Jonathan T. Overpeck

Director, Institute for the Study of Planet Earth

Professor, Department of Geosciences

Professor, Department of Atmospheric Sciences

Mail and Fedex Address:

Institute for the Study of Planet Earth

715 N. Park Ave. 2nd Floor

University of Arizona

Tucson, AZ 85721

direct tel: xxx xxxx xxxx

fax: xxx xxxx xxxx

[1]http://www.geo.arizona.edu/

[2]http://www.ispe.arizona.edu/

--

Jonathan T. Overpeck
Director, Institute for the Study of Planet Earth
Professor, Department of Geosciences
Professor, Department of Atmospheric Sciences

Mail and Fedex Address:
Institute for the Study of Planet Earth
715 N. Park Ave. 2nd Floor
University of Arizona
Tucson, AZ 85721
direct tel: xxx xxxx xxxx
fax: xxx xxxx xxxx
http://www.geo.arizona.edu/
http://www.ispe.arizona.edu/

References

1. http://www.geo.arizona.edu/
2. http://www.ispe.arizona.edu/

Original Filename: 1142389768.txt | Return to the index page | Permalink | Earlier Emails | Later Emails

From: Jonathan Overpeck <jto@u.arizona.edu>
To: edwardcook <drdendro@xxxxxxxxx.xxx>
Subject: Re: NRC Committee on Surface Temperature Reconstructions
Date: Tue, 14 Mar 2006 21:29:xxx xxxx xxxx
Cc: Eystein Jansen <eystein.jansen@xxxxxxxxx.xxx>, Keith Briffa <k.briffa@xxxxxxxxx.xxx>

Hi Ed (and Keith) - this looks good. For what it's worth, here are some comments:

1. I agree Keith should send in an independent letter by email too (I'd put both on
letterhead or at least include as pdf attachments, so email forwarding wouldn't have the
chance of messing it up) .

2. I would say right up front - first line that you'd like your letter (s) to go to all
committee members, if possible with a cc to you. Don't leave any wriggle room.

3. cc to G. North and B. Otto-Bliesner - again, so there is no doubt that this gets to
everyone

4. no need to mention IPCC. Focus on the science and the NRC review. Don't want to
introduce extra politics.

Thanks both for doing this - I agree there is a real need to ensure that the panel has the
science from the experts.

Best, peck

Hi everyone,
Here is a draft of what I want to quickly send to
Ian Kraucunas, Ph.D.
Board on Atmospheric Sciences and Climate
National Research Council of The National Academies
500 Fifth Street NW, Keck 705
Washington, DC 20001
Email: ikraucunas@xxxxxxxxx.xxx
Phone: (2xxx xxxx xxxx
Fax: (2xxx xxxx xxxx
He originally invited me to talk before the NRC. I do not have any other information on
who to send it too. Please let me know what you think, but don't be too pedantic or
critical at this stage. I get the feeling we have very little time to make an impact on
the NRC committee and its report. I personally think that I am correct as far as I can
take the argument. Let me know if I should send this on to Richard as well.
Ed
Dear Ian,
I have heard via emails and telephone conversations about some rather serious
developments that could have an unfairly negative impact on the use of tree rings for
reconstructing past climate and the upcoming IPCC assessment, especially that related to
surface temperatures. Apparently as part of her talk Rosanne D'Arrigo mentioned the
phenomenon of "divergence" between instrumental temperatures and tree growth in the
latter few decades of the 20th century. The large-scale nature of this phenomenon was
first described in Nature by Keith Briffa back in 1998 (Briffa et al., 1998) and to this
day its cause is not well understood at all. A number of hypotheses have been mentioned,
which range from natural (climatic change) to anthropogenic (i.e. pollution related),
but the actual cause is still unknown.
Somewhat alarmingly, it is my impression now the the NRC committee members and other
influential participants of the meeting have come to the conclusion that the observed
20th century "divergence" calls into serious question the value of the tree-ring
reconstructions of temperatures over the past millennium. The implicit assumption being
made is that the "divergence" is being caused by climatic change related to 20th century
warming, conditions that could have also prevailed back during the Medieval Warm Period
(MWP) some xxx xxxx xxxxyears in the past. If this were the case, then the concerns of the
committee would be justified. However, the available evidence does not support such a
conclusion. In a paper I published in Quaternary Science Reviews in 2004 (Cook et al.,
2004), I reviewed the properties and interpretation of the tree-ring data used in the
Esper et al. (2002) paper published in Science. The reasonably well distributed set of
tree-ring data in both boreal and more temperate latititude sites around the Northern
Hemisphere allowed me to split up the data into sub-regional ensembles, including 8
sites in the 55-70

Original Filename: 1142457385.txt | Return to the index page | Permalink | Earlier Emails | Later Emails

From: Tim Osborn <t.osborn@xxxxxxxxx.xxx>
To: oyvind.paasche@xxxxxxxxx.xxx,Eystein Jansen <Eystein.Jansen@xxxxxxxxx.xxx>
Subject: Re: Fwd: Re: Fwd: Ch06 Figure Check
Date: Wed, 15 Mar 2006 16:16:25 +0000
Cc: Jonathan Overpeck <jto@u.arizona.edu>,Keith Briffa <k.briffa@xxxxxxxxx.xxx>

<x-flowed>
Here's the next one

---------------------
Dear Oyvind,

sorry for the delay, I've been off work for a couple of days due to
unexpected family illness.

here are the EPS format figures. I'll send in separate emails due to
their size. I've tried to number them correctly according to the new
numbering, though please open them to check they look ok.

One thing to note is that I have separate files for the two panels of
the MWP box figure, and also the forcings/models figure is also in
two files. They are all labelled appropriately, with the panel part
in the filename, so I hope this is no problem!?

You should get these files:

ipccar4_fig6.10.eps
ipccar4_fig6.11.eps
ipccar4_fig6.12.eps
ipccar4_fig6.13abcd.eps & ipccar4_fig6.13e.eps
ipccar4_box6.4_fig1a.eps & ipccar4_box6.4_fig1b.eps

Please let me know if they don't all arrive!

Cheers

Tim

At 09:00 08/03/2006, Eystein Jansen wrote:
>Dear Tim and Bette,
>first I wish to thank you again for your particularly outstanding
>and hard work for the SOD. Your work in particular really has made
>the new draft a lot better than the FOD.
>There is one small remaining issue, however, as noted by the TSU in
>the message posted below. We need high res version, i.e. eps. files
>of your figures. At present we only have the ones sent in word files.
>Could you send the eps. files to us and

Original Filename: 1142469228.txt | Return to the index page | Permalink | Earlier Emails | Later Emails

From: edwardcook <drdendro@xxxxxxxxx.xxx>
To: Jonathan Overpeck <jto@u.arizona.edu>, Keith Briffa <k.briffa@xxxxxxxxx.xxx>, Eystein Jansen <eystein.jansen@xxxxxxxxx.xxx>
Subject: Fwd: Comment on NRC Workshop
Date: Wed, 15 Mar 2006 19:33:48 +0700
Cc: edwardcook <drdendro@xxxxxxxxx.xxx>

Hi Gents, Here is what I just sent off to NRC, cc'd to Gerry North and Bette Otto-Bliesner.
Ed Begin forwarded message: > From: edwardcook > Date: March 15, 2006 7:23:23 PM GMT+07:00
> To: "Kraucunas, Ian" > Cc: edwardcook , g-north@xxxxxxxxx.xxx, > ottobli@xxxxxxxxx.xxx > Subject:
Comment on NRC Workshop > > Ian Kraucunas, Ph.D. > Board on Atmospheric Sciences and
Climate > National Research Council of The National Academies > 500 Fifth Street NW, Keck
705 > Washington, DC 20001 > > Dear Dr. Kraucunas, > > I request that this document (also
attached as Cook_NRC.pdf) and > the attached scientific paper (2001_Cook_QSR.pdf) be
forwarded to > all NRC committee members who participated in the recent NRC > workshop
"Surface Temperature Reconstructions for the Past 2,000 > Years: Synthesis of Current
Understanding and Challenges for the > Future", ideally with a cc to me when this is done.
I have heard > via emails and telephone conversations about a serious concern > raised
about tree rings by some committee members and invited > participants at the NRC workshop.
This concern could have an > unfairly negative impact on the use of tree rings for >
reconstructing past climate, especially that related to surface air > temperatures, hence
my letter to you and the committee. As part of > her talk, Dr. Rosanne D'Arrigo mentioned
the discovery of > "divergence" between instrumental temperatures and tree growth > during
the last few decades of the 20th century at selected boreal > sites in the Northern
Hemisphere. The affected trees > systematically under-responded to increasing temperatures,
i.e. > they grew more slowly than they should have based on a well-fitted > linear response
model applied to the data prior to the onset of > "divergence". The large-scale occurrence
of this change in > responsiveness has also been described by Keith Briffa (Briffa et >
al., 1998) in Nature. A number of hypotheses have been proposed to > explain it, which
range from natural (climatic change) to > anthropogenic (pollution related), but the actual
cause is still > unknown. This phenomenon needed to be mentioned by Dr. D'Arrigo, > but it
appears to have taken on a level of specious importance that > is not justified by the
evidence. > > Perhaps not surprisingly, but also somewhat alarmingly, it is my >
understanding that some NRC committee members and other influential > participants have
come to the conclusion that the observed 20th > century "divergence" calls into serious
question the value of the > tree-ring reconstructions of temperatures over the past >
millennium. The implicit assumption apparently being made is that > the "divergence" being
caused by environmental conditions in the > 20th century could have also prevailed back
during times like the > Medieval Warm Period (MWP) some xxx xxxx xxxxyears in the past. If >
this were the case, then the concern raised by some at the workshop > would be justified.
However, the available evidence does not > support such a conclusion. In a paper I
published in Quaternary > Science Reviews in 2004 (Cook et al., 2004), I reviewed the >
properties and interpretation of the tree-ring data used in the > Esper et al. (2002) paper
published in Science. The reasonably > well distributed set of tree-ring data in both
boreal and more > temperate latitude sites around the Northern Hemisphere allowed me > to
split up the data into sub-regional ensembles, including 8 sites > in the 55-70° north
band and 6 sites in the 30-55° south band. > The purpose was to demonstrate the overall
robustness of the multi- > centennial temperature signal in the tree-ring data. This plot >
from the QSR paper is embedded below and the paper is sent being > sent as an attachment.
The importance of this plot to the > "divergence" debate follows next. > > In their paper,
Briffa et al. (1998) showed that the "divergence" > between tree growth and temperatures
was largely restricted to the > region covered by the north band described in Cook et al.
(2004). > Consistent with that finding, the north ensemble mean shown below > (blue curve)
reveals a serious downturn in growth after about > 1950. This is an expression of the
large-scale "divergence" > described by Briffa et al. (1998) and also by Dr. D'Arrigo in
her > NRC talk. In contrast, the south ensemble mean (red curve) shows > the opposite
growth trajectory after 1950, i.e. a substantial > growth increase that is much more
consistent with 20th century > warming. If one then follows the plots back in time, all
sub- > region ensemble means track each other remarkably well at multi- > centennial time
scales even when they enter the putative MWP > xxx xxxx xxxxyears ago. In fact, at no time
prior to the 20th century > is there a separation between north and south that is at all >
comparable to that found after 1950. This result indicates that no > large-scale
"divergence" of the order found during the 20th century > occurred during the MWP even
though that period is suggested to > have been somewhat warmer than average overall. It
thus refutes > the argument that "divergence" of the kind found in the 20th > century could
very well have happened in the past, thus implying > that tree rings cannot produce
reliable reconstructions of past > temperatures. It also supports the existence of an
admittedly > unknown anthropogenic cause of the 20th century "divergence". The > lack of
any known cause is unfortunate, but this would be true > regardless of how the importance
of "divergence" is interpreted. > > I am not aware of ANY evidence that demonstrates the
occurrence of > large-scale "divergence" between tree growth and climate prior to > the
20th century. Indeed, the available evidence indicates just > the opposite. In my opinion
it is therefore unjustified to call > into question the use of tree rings for
reconstructing temperatures > over the past millennium based on a naïve and inappropriate
> extrapolation of the growth "divergence" problem into the past when > it appears to be
unique to the 20th century. The NRC committee > members must consider this in their report
if it is to have the > necessary scientific credibility that is expected of it. > >
References > > Briffa, K.R., Schweingruber, F.H., Jones, P.D., Osborn, T.J., > Shiyatov,
S.G., Vaganov, E.A. 1998. Reduced sensitivity of recent > tree-growth to temperature at
high northern latitudes. Nature 391: > xxx xxxx xxxx. > > Esper, J., Cook, E.R., Schweingruber,
F.H. 2002. Low-frequency > signals in long tree-ring chronologies for reconstructing past >
temperature variability. Science 295: 2xxx xxxx xxxx. > > Cook, E.R., Esper, J., D'Arrigo, R.D.
2004. Extra-tropical Northern > Hemisphere land temperature variability over the past 1000
years. > Quaternary Science Reviews 23(20-22): 2xxx xxxx xxxx. > > Sincerely, > > Edward R. Cook
> > ================================== > Dr. Edward R. Cook > Doherty Senior Scholar and >
Director, Tree-Ring Laboratory > Lamont-Doherty Earth Observatory > Palisades, New York
10964 USA > Email: drdendro@xxxxxxxxx.xxx > Phone: xxx xxxx xxxx> Fax: xxx xxxx xxxx>
================================== > ? ? ? Hi Gents,

Here is what I just sent off to NRC, cc'd to Gerry North and Bette Otto-Bliesner.

Ed
Begin forwarded message:

From: edwardcook <[1]drdendro@xxxxxxxxx.xxx>

Date: March 15, 2006 7:23:23 PM GMT+07:00

To: "Kraucunas, Ian" <[2]IKraucunas@xxxxxxxxx.xxx>

Cc: edwardcook <[3]drdendro@xxxxxxxxx.xxx>, [4]g-north@xxxxxxxxx.xxx, [5]ottobli@xxxxxxxxx.xxx

Subject: Comment on NRC Workshop

Ian Kraucunas, Ph.D.

Board on Atmospheric Sciences and Climate

National Research Council of The National Academies

500 Fifth Street NW, Keck 705

Washington, DC 20001

Dear Dr. Kraucunas,

I request that this document (also attached as Cook_NRC.pdf) and the attached scientific
paper (2001_Cook_QSR.pdf) be forwarded to all NRC committee members who participated in the
recent NRC workshop "Surface Temperature Reconstructions for the Past 2,000 Years:
Synthesis of Current Understanding and Challenges for the Future", ideally with a cc to me
when this is done. I have heard via emails and telephone conversations about a serious
concern raised about tree rings by some committee members and invited participants at the
NRC workshop. This concern could have an unfairly negative impact on the use of tree rings
for reconstructing past climate, especially that related to surface air temperatures, hence
my letter to you and the committee. As part of her talk, Dr. Rosanne D'Arrigo mentioned
the discovery of "divergence" between instrumental temperatures and tree growth during the
last few decades of the 20th century at selected boreal sites in the Northern Hemisphere.
The affected trees systematically under-responded to increasing temperatures, i.e. they
grew more slowly than they should have based on a well-fitted linear response model applied
to the data prior to the onset of "divergence". The large-scale occurrence of this change
in responsiveness has also been described by Keith Briffa (Briffa et al., 1998) in Nature.
A number of hypotheses have been proposed to explain it, which range from natural (climatic
change) to anthropogenic (pollution related), but the actual cause is still unknown. This
phenomenon needed to be mentioned by Dr. D'Arrigo, but it appears to have taken on a level
of specious importance that is not justified by the evidence.

Perhaps not surprisingly, but also somewhat alarmingly, it is my understanding that some
NRC committee members and other influential participants have come to the conclusion that
the observed 20th century "divergence" calls into serious question the value of the
tree-ring reconstructions of temperatures over the past millennium. The implicit
assumption apparently being made is that the "divergence" being caused by environmental
conditions in the 20th century could have also prevailed back during times like the
Medieval Warm Period (MWP) some xxx xxxx xxxxyears in the past. If this were the case, then
the concern raised by some at the workshop would be justified. However, the available
evidence does not support such a conclusion. In a paper I published in Quaternary Science
Reviews in 2004 (Cook et al., 2004), I reviewed the properties and interpretation of the
tree-ring data used in the Esper et al. (2002) paper published in Science. The reasonably
well distributed set of tree-ring data in both boreal and more temperate latitude sites
around the Northern Hemisphere allowed me to split up the data into sub-regional ensembles,
including 8 sites in the 55-70

What are others looking for?