Dear Ed, Tom, Keith, etc.
In keeping w/ the spirit of Tom's and Keith's emails, I wanted to stress, before we all
break for the weekend, that this is ultimately about the science, its not personal. If my
comments seemed to assail e.g. Keith's motives or integrity, etc. I believe that they were
misunderstood (as  I tried to clarify that in my previous message), but I can see that
there was a potential for misunderstanding of my message (precision in wording is very
important) given the high levels of sensitivity in this debate. So I wanted to leave no
uncertainty about that. And of course, I very much apologize to Keith (and Tim) if they
took them my comments that way. They, again, were most decidedly not intended that way.
I hope we can resolve the scientific issues objectively, and w/out injecting or any
personal feelings into any of this. There are some substantial scientific differences here,
lets let them play out the way they are supposed to, objectively, and in the peer reviewed
literature.
Enjoy the weekend all.
cheers,
Mike
At 01:35 PM 4/12/02 -0400, Ed Cook wrote:
Hi Mike, Tom, etc,
Okay, I am quite happy to give this debate a rest, although I am sure that the issues
brought up will still be grounds for scientific debate. I admit to getting a bit riled
when I saw the ECS results on the MWP described as "perilous" because I regard that as
being an unfair characterization of the work presented. Be that as it may, my reply to
Science will be very carefully worded so as not to inflame the issues. Nuff said. Have a
good weekend. I certainly intend to do so.
Ed
Ed and others,
I thought I too should chime in here one last time...
I'll leave it to you, Malcolm, Keith and others to debate out the issue of any
additional uncertainties, biases, etc. that might arise from RCS in the presence of
limited samples. That is beyond my range of expertise. But since this is a new and
relatively untested approach, and it is on the basis of this approach that other
estimates are being argued to be "underestimates", we would indeed have been remiss now
to point this out in our letter.
The wording "perilous" perhaps should be changed, by I very much stand by the overall
sentiment expressed by Malcolm in our piece with regard to RCS.
One very important additional point that Malcolm makes in his message is that
conservative estimates of uncertainties, appropriate additional caveats, etc. were
indeed all provided in MBH99, and I have always been careful to interpret our results in
the context of these uncertainties and caveats. IPCC '2001 was careful to do so to, and
based its conclusions within the context of the uncertainties (hence the choice of the
conservative term "likely" in describing the apparently unprecedented nature of late
20th century warmth) and, moreover, on the collective results of many independent
reconstructions. Briffa & Osborn would have you believe that IPCC '2001's conclusions in
this regard rested on MBH99 alone. Frankly, Keith and Tim, I believe that is unfair to
the IPCC, whether or not one cares about being fair to MBH or not.
What is unfortunate here then is that Esper et al has been "spun" i to argue that MBH99
underestimates the quantity it purports to estimate, full Northern Hemisphere annual
mean temperature. Given the readily acknowledged level of uncertainty in both estimates,
combined with the   "apples and oranges" nature of the comparison between the two (which
I have sought to clarify in my letter to Science, and in my messages to you all, and the
comparison plot I provided),   I believe it is either sloppy or disingenuous reasoning
to argue that this is the case. The fact that this sloppiness also readily serves the
interests of the skeptics is quite unfortunate, but it is indeed beside the point!
It would probably also be helpful for me to point out, without naming names, that many
of our most prominent colleagues in the climate research community, as well government
funding agency representatives,  have personally contacted me over the past few weeks to
express their dismay at the way they believe this study was spun. I won't get into the
blame game, because there's more than enough of that to go around. But when the leaders
of our scientific research community and our funding managers personally alert us that
they believe the credibility of our field has been damaged, I think it is time for some
serious reflection on this episode.
that's my final 2 cents,
Mike
At 10:21 AM 4/12/02 -0400, Ed Cook wrote:
Just a few comments here and then I'm done.
Dear Ed and Mike and others,
All of our attempts, so far, to estimate hemisphere-scale
temperatures for the period around 1000 years ago are
based on far fewer data than any of us would like. None
of the datasets used so far has anything like the
geographical distribution that experience with recent
centuries indicates we need, and no-one has yet found a
convincing way of validating the lower-frequency
components of them against independent data. As Ed
wrote, in the tree-ring records that form the backbone of
most of the published estimates, the problem of poor
replication near the beginnings of records is particularly
acute, and ubiquitous. I would suggest that this problem
probably cuts in closer to 1600 than 1400 in the several
published series. Therefore, I accept that everything we
are doing is preliminary, and should be treated with
considerable caution.
Therefore, I would guess that you would apply the word "perilous" to everyones'
large-scale NH reconstructions covering the past 500-1000 years including those that you
have been involved in. Why the sudden increase in caution now? It sounds very
self-serving to me for you to call ECS "perilous" and not describe every other
large-scale reconstruction in that way as well.
I differ from Ed, and his co-authors,
in believing that these problems have a special
significance for the particular implementation of RCS
they used, in the light of one of their conclusions that
depends heavily on that implementation.
As I understand what Ed, Keith and Hal Fritts have
written at various times about RCS, and from my own
limited experience with the method, it is extremely
important to have strong replication, and I don't see 50-70
samples probably from 25-35 trees as a big sample. For
reference, most chronologies used in dendroclimatology
are based on 10-40 trees, that is 20-80 samples at 2 cores
per tree for a single "site", usually a few hectares.
Here are two passages from Briffa et al., 1992:
page 114, column 1, last paragraph, "For a chronology
composed of the same number of samples, one would
therefore expect a larger statistical uncertainty using this
approach than in a chronology produced using
standardization curves fitted to the data from individual
trees...............The RCS method therefore requires greater
chronology depth (i.e. greater sample replication) to
provide the same level of confidence in its representation
of the hypothetical "true" chronology." ECS mention this
issue.
As I said in my previous email, we hid nothing in terms of the uncertainty concerning
the pre-1200 interval. Are you suggesting that we should not have even shown those
results? If so, that is ridiculous.
page 114, column 1, third paragraph, there is a discussion
of the problems arising from applying RCS when pith age
is not known, "In the ring-width data, the final
standardization curve probably slightly underestimates
the width of young trees and could therefore impart a
small positive bias to the standardized ring-width indices
for young rings in a number of series. However, this
effect will be insignificant when the biased indices are
realigned according to calendar growth years and
averaged with many other series." The problem here is
that this latter condition is not met (in my view), and the
"small positive bias" that may be retained could turn out
to be important to the most controversial conclusion of
ECS (the Medieval question).
I can't speak for Jan here, but most of the data he used came from Schweingruber's lab.
I believe that pains were taken to estimate the pith offset and that Jan used this
information in his RCS analyses. Jan would be best to comment here. In any case, Jan has
done a number of experiments in which he has artificially added large pith offset errors
into the RCS analysis and the resulting bias is small. So, I do not believe that your
"view" is correct.
I also suspect that Keith
and colleagues underestimated both the size and
variability of the loss of years at the beginning of records,
but the point stands even if this is not so. So far as I can
see, ECS do not mention this issue, at least in the context
of a possible positive bias.
Are you claiming that the only possible bias is positive? I can show you examples of a
probable negative bias using RCS.
The discussion of RCS in the
supplementary materials seems to assume good
replication.
It was a generic description of the method. The replication is clearly shown in the
supplementary materials section as well as in the main paper. If you don't like the
replication, that is your opinion. I would love to have more replication as well. Who
wouldn't. But we did show the uncertainties, which you seem to ignore in your criticism.
Ironically, the ECS estimates of warmth in the MWP are not that dissimilar to those seen
in MBH, as ECS Fig. 3 shows. Are the MBH estimates of MWP warmth also similarly biased?
ECS, as Ed rightly points out, clearly indicate, in both
words and diagrams at several points in their paper and in
the supplementary materials, that the number of sites and
number of samples they used decreases sharply before
1200. Even so, ECS gives  prominence (second sentence
of the abstract, for example) to the reconstruction in that
very period, and makes a comparison with the magnitude
of 20th-century warming. All the methods, and their
realizations so far, have significant problems. In our letter
(Mike and I) we draw attention to a specific problem with
this implementation of RCS that has a special bearing on
the reconstruction of a period to which ECS have drawn
attention. Hence the strong note of caution about the ECS
conclusion on the comparison between the 10th/11th and
late 20th centuries.
I hope it's clear from this that I don't disagree with the
general proposition that all existing reconstructions of
hemipsphere-scale temperatures 1000 years ago (or even
for all the first half of the second millennium AD) should
be viewed as very preliminary. If anyone is interested I
attach a short note on the replication in the year AD 1000
of records used in MBH99 to give an idea of what we are
up against.
There is obviously a lot more we can debate about here. I will simply stop here by
saying that I stand by the results shown in ECS and will say so in my reply to your
letter, pointing out that the use of the word "perilous" could be just as easily be
applied to MBH.
We all have a lot to do. I see four important tasks - 1)
more investigation of the strengths and limitations of
methods like RCS and age-banding - for example, how
many samples would have been enough in this case, does
the RC change through time? and so on; 2) use of tree-
ring records where the loss of low-frequency information
is least - those with long segments from open stands; 3)
the search for tree-ring parameters without age/size
related trend; 4) the development of completely
independent proxies with intrinsically better low-
frequency fidelity.
Cheers, Malcolm
The Briffa et al reference is to the 1992 paper, Climate
Dynamics, 7:111-119
Hi Ed,
OK--thanks for your response. I'll let Malcolm respond to the
technical issues regarding RC. I'm not really qualified to do so
myself anyway. Your other points are well taken...
Cheers,
Mike
At 12:09 PM 4/11/02 -0400, Edward Cook wrote:
Hi Mike,
Thanks for the reply. I too do not want to see anything
personal in our disagreements. It would be a shame if it got to
that and it shouldn't. I don't think that the science we are
talking about is sufficiently known yet to claim the "truth",
which is why we are having some of our disagreements. I mainly
wanted to clarify some issues relating to some criticisms of the
ECS results that I thought were not totally fair. My biggest
complaint is with Malcolm's contribution to your letter because it
really isn't fair to use such words as "perilous". ECS did not
hide anything and the uncertainties are clearly indicated in EGS
>     Figs. 2 and 3. So, you can make your own judgement. However,
Malcolm's opinion does not invalidate the ECS record. If Malcolm's
statement is correct, than ALL previous estimates of NH
temperature over the past 1000 years are "perilous", especially
before AD 1400 when the number of series available declines
significantly in most records.
Ed
Ed,
It will take some time to digest these comments, but my
initial response is one of some disappointment. I will
resist the temptation to make the letter to Science
available to the others on this list, because of my fears of
violating the embargo policy (I know examples of where doing so
has led to Science retracting a piece form publication). So thanks
for also resisting the temptation to do so...
But I must point out that the piece by Malcolm and me
is very similar in its content to the letter of clarification that
you and I originally crafted to send to Science some weeks ago,
before your co-author objected to your involvement! If there is no
objection on your part, I'd be happy to send that to everyone,
because it is not under consideration in Science (a quite
unfortunate development, as far as I'm concerned). The only real
change from that version is the discussion of the use of RCS. That
is in large part Malcolm's contribution, but I stand behind what
>     Malcolm says. I think there are some real sins of omission with
regard to the use of RCS too, and it would be an oversight on our
part now to comment on these.
Finally, with regard to the scaling issues, let me simply
attach a plot which speaks more loudly than several
pages possibly could The plot takes Epser et al (not
smoothed, but the annual values) and scales it against the
full Northern Hemisphere instrumental record 1856-1990
annual mean record, and compares against the entire 20th
century instrumental record (1856-1999), as well as with
MBH99 and its uncertainties.
Suppose that Esper et al is indeed representative of the
fullNorthern Hemisphere annual mean, as MBH99
purports to be. To the extent that differences emerge
between the two in assuming such a scaling, I interpret
them as differences which exist due to the fact that the
extratropical Northern Hemisphere series and full
Northern Hemisphere series likely did not co-vary in the
past the same way they co-vary in the 20th century (when
both are driven predominantly, in a relative sense, by
anthropogenic forcing, rather than natural forcing and
internal variability). What the plot shows is quite
remarkable. Scaled in this way, there is remarkably little
difference between Esper et al and MBH99 in the first
place (the two reconstructions are largely within the error
estimates of MBH99!)!, but moreover, where they do
differ, this could be explainable in terms of patterns of
enhanced mid-latitude continental response that were
discussed, for example, in Shindell et al (2001) in
Science last December. So I think this plot says a lot. Its
say that there are some statistically significant
differences, but certainly no grounds to use Esper et al to
contradict MBH99 or IPCC '2001 as, sadly, I believe at
least one of the published pieces tacitly appears to want
to do.
It is shame that such a plot, which I think is a far more
meaningful comparison of the two records, was not
shown in either Esper et al or the Briffa & Osborn
commentary. I've always given the group of you adequate
opportunity for commentary on anything we're about to
publish in Nature or Science. I am saddened that many of
my colleagues (and, I have always liked to think friends)
didn't affort me the same opportunity before this all
erupted in our face. It could have been easily avoided.
But that's water under the bridge.
>
Finally, before any more back-and-forths on this, I want
to make sure that everyone involved understands that
none of this was in any way ever meant to be personal, at
least not on my part (and if it ever has, at least on my
part, seemed that way, than I offer my apologies--it was
never intended that way). This is completely about the
"science". To the extent that I (and/or others) feel that the
science has been mis-represented in places, however, I personally
will work very hard to make sure that a more balanced view is
available to the community. Especially because the implications
are so great in this case. This is what I sought to do w/ the NYT
piece and my NPR interview, and that is what I've sought to do
(and Malcolm to, as far as I'm concerned) with the letter to
Science. Being a bit sloppy w/ wording, and omission, etc. is
something we're all guilty of at times. But I do consider it
somewhat unforgivable when it is obvious how that sloppiness can
be exploited. And you all know exactly what I'm talking about!
So, in short, I think are some fundamental issues over
which we're in disagreement, and where those exist, I will
not shy away from pointing them out. But I hope that is
not mis-interpreted as in any way personal.
I hope that suffices,
>
Mike
p.s. It seemed like an omission to not cc in Peck and
Scott Rutherford on this exchange, so I've done that. I
hope nobody minds this addition...
At 10:57 AM 4/11/02 -0400, Edward Cook wrote:
Hi Mike and Malcolm,
I have received the letter that you sent to Science
and will respond to it here first in some detail and
later in edited and condensed form in Science.
Since much of what you comment and criticize on
has been disseminated to a number of people in
your (Mike's) somewhat inflammatory earlier
emails, I am also sending this lengthy reply out to
everyone on that same email list, save those at
Science. I hadn't responded in detail before, but
do so now because your criticisms will soon be in
the public domain. However, I am not attaching
your letter to Science to this email since that is
not yet in the public domain. It is up to you to
send out your submitted letter to everyone if you
wish.
I must say at the beginning that some parts of
your letter to Science are as "flawed" as your
claims about Esper et al. (hereafter ECS). The
Briffa/Osborn perspectives piece points out an
important scaling issue that indeed needs further
examination. However, to claim as you do that
they show that the ECS 40-year low-pass
temperature reconstruction is "flawed" begs the
question: "flawed" by how much? It is not at all
clear that scaling the annually resolved RCS
chronology to annually resolved instrumental
temperatures first before smoothing is the correct
way to do it. The ECS series was never created to
examine annual, or even decadal, time-scale
temperature variability. Rather, as was clearly
indicated in the paper, it was created to show how
one can preserve multi-centennial climate
variability in certain long tree-ring records, as a
refutation of Broecker's truly "flawed" essay. As
ECS showed in their paper (Table 1), the high-
frequency correlations with NH mean annual
temperatures after 20-year high-pass filtering is
only 0.15. That result was expected and it makes
no meaningful difference if one uses only extra-
tropical NH temperature data. So, while the
amplitude of the temperature-scaled 40-year low-
pass ECS series might be on the high end (but
still plausible given the gridded borehole
temperature record shown in Briffa/Osborn),
scaling on the annually resolved data first would
probably have the opposite effect of excessively
>     reducing the amplitude. I am willing to accept an
intermediate value, but probably not low enough
to satisfy you. Really, the more important result
from ECS is the enhanced pattern of multi-
centennial variability in the NH extra-tropics over
the past 1100 years. We can argue about the
amplitude later, but the enhanced multi-centennial
variability can not be easily dismissed. I should
also point out, again, that you saw Fig. 3 in ECS
BEFORE it was even submitted to Science and
never pointed out the putative scaling "flaw" to
me at that time.
With regards to the issue of the late 20th century
warming, the fact that I did not include some
reference to or plot of the up-to-date instrumental
temperature data (cf. Briffa/Osborn) is what I
regard as a "sin of omission". What I said was
that the estimated temperatures during the MWP
in ECS "approached" those in the 20th century
portion of that record up to 1990. I don't consider
the use of "approached" as an egregious
overstatement. But I do agree with you that I
should have been a bit more careful in my
wording there. As you know, I have publicly
stated that I never intended to imply that the
MWP was as warm as the late 20th century (e.g.,
>     my New York Times interview). However, it is a
bit of overkill to state twice in the closing
sentences of the first two paragraphs of your
letter that the ECS results do not refute the
unprecedented late 20th century warming. I
would suggest that once is enough.
ECS were also very clear about the extra-tropical
nature of their data. So, what you say in your
letter about the reduced amplitude in your series
coming from the tropics, while perhaps worth
pointing out again, is beating a dead horse.
However, I must say that the "sin of omission" in
the Briffa/Osborn piece concerning the series
shown in their plot is a bit worrying. As they say
in the data file of series used in their plot (and in
Keith's April 5 email response to you),
Briffa/Osborn only used your land temperature
estimates north of 20 degrees and recalibrated the
mean of those estimates to the same domain of
land-only instrumental temperatures using the
same calibration period for all of the other non-
borehole series in the same way. I would have
preferred it if they had used your data north of
30N to make the comparisons a bit more one-to-
one. However, I still think that their results are
interesting. In particular, they reproduce much of
the reduced multi-centennial temperature
variability seen in your complete NH
reconstruction. So, if the amplitude of scaled
ECS multi-centennial variability is far too high
(as you would apparently suggest), it appears that
it is also too low in your estimates for the NH
extra-tropics north of 20N. I think that we have
to stop being so aggressive in defending our
series and try to understand the strengths and
weaknesses of each in order to improve them.
That is the way that science is supposed to work.
I must admit to being really irritated over the
criticism of the ECS tree-ring data standardized
using the RCS method. First of all, ECS
acknowledged up front the declining available
data prior to 1200 and its possible effect on
interpreting an MWP in the mean record. ECS
also showed bootstrap confidence intervals for
the mean of the RCS chronologies and showed
where the chronologies drop out. Even allowing
for the reduction in the number of represented
sites before 1400 (ECS Fig. 2d), and the
reduction in overall sample size (ECS Fig. 2b),
there is still some evidence for significantly
above average growth during two intervals that
can be plausibly assigned to the MWP. Of course
>     we would like to have had all 14 series cover the
past 1000-1200 years. This doesn't mean that we
can't usefully examine the data in the more
weakly replicated intervals. In any case, the
replication in the MWP of the ECS chronology is
at least as good as in other published tree-ring
estimates of large-scale temperatures (e.g., NH
extra-tropical) covering the past 1000+ years. It
also includes more long tree-ring records from the
NH temperate latitudes than ever before. So to
state that "this is a perilous basis for an estimate
of temperature on such a large geographic scale"
is disingenuous, especially when it is unclear how
many millennia-long series are contributing the
majority of the temperature information in the
Mann/Bradley/Hughes (MBH) reconstruction
prior to AD 1400. Let's be balanced here.
I basically agree with the closing paragraph of
your letter. The ECS record was NEVER
intended to refute MBH. It was intended, first
and foremost, to refute Broecker's essay in
Science that unfairly attacked tree rings. To this
extent, ECS succeeded very well. The
comparison of ECS with MBH was a logical
thing to do given that it has been accepted by the
>     IPCC as the benchmark reconstruction of NH
annual temperature variability and change over
the past millennium. Several other papers have
made similar comparisons between MBH and
other even more geographically restricted
estimates of past temperature. So, I don't
apologize in the slightest for doing so in ECS.
The correlations in Table 2 between ECS and
MBH were primarily intended to demonstrate the
probable large-scale, low-frequency temperature
signal in ECS independent of explicitly
calibrating the individual RCS chronologies
before aggregating them. The results should
actually have pleased you because, for the 20-200
year band, ECS and MBH have correlations of
0.60 to 0.68, depending on the period used.
Given that ECS is based on a great deal of new
data not used in MBH, this result validates to a
reasonable degree the temperature signal in MBH
in the 20-200 year band over the past 1000 years.
Given the incendiary and sometimes quite rude
emails that came out at the time when ECS and
Briffa/Osborn were published, I could also go
into the whole complaint about how the review
process at Science was "flawed". I will only say
that this is a very dangerous game to get into and
complaints of this kind can easily cut both ways.
I will submit an appropriately edited and
condensed version of this reply to Science.
Regards,
Ed
--
=================================
Dr. Edward R. Cook
Doherty Senior Scholar
Tree-Ring Laboratory
Lamont-Doherty Earth Observatory
Palisades, New York 10964 USA
Phone: 1-845-365-8618
Fax: 1-845-365-8152
Email: drdendro@ldeo.columbia.edu
=================================
_____________________________________________
__________________________
Professor Michael E. Mann
Department of Environmental Sciences, Clark Hall
University of Virginia
Charlottesville, VA 22903
_____________________________________________
__________________________
e-mail: mann@virginia.edu Phone: (434) 924-
7770FAX: (434) 982-2137
[1]
ml
Attachment converted: Macintosh HD:esper-
scaledcompare1980.jpg (JPEG/JVWR) (0008FDE3)
--
=================================
Dr. Edward R. Cook
Doherty Senior Scholar
Tree-Ring Laboratory
Lamont-Doherty Earth Observatory
Palisades, New York 10964 USA
Phone: 1-845-365-8618
Fax: 1-845-365-8152
Email: drdendro@ldeo.columbia.edu
=================================
> ____________________________________________________
___________________
Professor Michael E. Mann
Department of Environmental Sciences, Clark Hall
University of Virginia
Charlottesville, VA 22903
____________________________________________________
___________________
e-mail: mann@virginia.edu Phone: (434) 924-7770FAX: (434)
982-2137
[2]
Malcolm Hughes
Professor of Dendrochronology
Laboratory of Tree-Ring Research
University of Arizona
Tucson, AZ 85721
520-621-6470
fax 520-621-8229
--
==================================
Dr. Edward R. Cook
Doherty Senior Scholar
Tree-Ring Laboratory
Lamont-Doherty Earth Observatory
Palisades, New York 10964  USA
Email:  drdendro@ldeo.columbia.edu
Phone:  845-365-8618
Fax:    845-365-8152
==================================
_______________________________________________________________________
Professor Michael E. Mann
Department of Environmental Sciences, Clark Hall
University of Virginia
Charlottesville, VA 22903
_______________________________________________________________________
e-mail: mann@virginia.edu   Phone: (434) 924-7770   FAX: (434) 982-2137
[3]
_______________________________________________________________________
Professor Michael E. Mann
Department of Environmental Sciences, Clark Hall
University of Virginia
Charlottesville, VA 22903
_______________________________________________________________________
e-mail: mann@virginia.edu   Phone: (434) 924-7770   FAX: (434) 982-2137
[4]
References
1.
2.
3.
4.
5.


HI Tim,
Thanks for your message. Yes, you guys have us beat on the early monday end of things!
Your points are all taken. I think we all agree there is much work left to be done, more
than enough for all of us to continue to be involved in constructive collaboration, etc.
Scott and I, for example, are almost done writing up the work based on  your visit w/ us
last year, and will send the initial draft on to you, Keith, and the others involved in the
near future. It will be a good chance to try to address a lot of these questions in an
article of adequate length to discuss the nuances that unfortunately cannot be addressed in
a shorter piece.
I also appreciate your more detailed comments about the comparisons, etc. Your points are
all reasonable ones. We can maintain an honest difference about how well those points were
conveyed in the Science piece (for example, you can imagine how the statement in your piece
"This record has a smaller amplitude of century-to-century variability, and is consistently
at or near the upper limit of alternate records produced by other researchers" might indeed
have been interpreted as setting MBH99 apart as, in your words, an "outlier").
We have good reason to believe that our reconstruction *will* in fact nderestimate
extratropical temperature means but far less so full globe/hemisphere-means prior to the
18th century because the basis functions that primarily set the extratropics apart from the
full hemispheric patterns  (e.g., NAO type patterns and other anomaly patterns largely
carried by EOFs #2 and #3) start to drop out from our basis set prior to the 18th century,
while the pattern that best resolves the full global and/or hemispheric mean (with note
from MBH98,  particularly large loadings primarily in the tropics and subtropics) still
remains. That is why we have never published an *extratropical* temperature reconstruction
prior to the 18th century. I would be happy to discuss this point with you and Keith and
others in more detail. Thus, I have compared Esper et al w/ our records in the manner
described in my previous email, which I think allows us to diagnose the extent to which
differing high-latitude and full-hemispheric patterns may, at times, explain the somewhat
modest differences between the records when similarly scaled to the full hemispheric
1856-1990 mean, and always, within  the context of the diagnosed uncertainties. There is no
guarentee, as you say, that the uncertainties are correct, but I personally believe they'll
stand up over time. You can call me on this 10 years from now, and somebody will owe
somebody a beer...
In any case, I hope and fully expect we can all continue to all be engaged in constructive
interaction & hopefully continued collaboration.  It will require some sensitivity on all
our part to the larger issues surrounding our work, and the way it gets presented to the
broader community, but I don't think that should be all that difficult.
I look forward to these more constructive interactions. I'll do my best to foster them,
Mike
At 01:57 PM 4/15/02 +0100, Tim Osborn wrote:
Dear all,
well, the time zone may let you have the last word before the weekend, but we can get
the first word in on a Monday morning!
At 22:35 12/04/02, Michael E. Mann wrote:
In keeping w/ the spirit of Tom's and Keith's emails, I wanted to stress, before we all
break for the weekend, that this is ultimately about the science, its not personal. If
my comments seemed to assail e.g. Keith's motives or integrity, etc. I believe that they
were misunderstood (as  I tried to clarify that in my previous message), but I can see
that there was a potential for misunderstanding of my message (precision in wording is
very important) given the high levels of sensitivity in this debate. So I wanted to
leave no uncertainty about that. And of course, I very much apologize to Keith (and Tim)
if they took them my comments that way. They, again, were most decidedly not intended
that way.
Thanks for clarifying that, Mike.  I think that both Keith and I interpreted your
earlier e-mail as being more critical of us than you actually meant it to be.
Most issues surrounding the recent Esper et al. and Briffa & Osborn pieces seem to have
been covered adequately already.  There are just a couple of issues on which I'd like to
add a few comments, hopefully clarifying the situation rather than opening up more
avenues for debate.
The first relates to the purpose and style of the Briffa & Osborn piece.  Perspectives
are brief, non-technical and not peer-reviewed.  Our instructions were: "The Perspective
should provide an overview of recent research in the field and explain to the general
reader why the work is particularly exciting."  Is it any surprise then that we should
focus on the new insights provided by the Esper et al. work, and that it suggests a
different climate history than earlier work?  And that the constraints of the
perspectives format (in terms of length, audience and style) prevented us from listing
ALL the caveats and uncertainties related to this and earlier reconstructions and that
might be of relevance to their intercomparison?  I don't think it is surprising, nor do
I think we should be criticised for it.
Moreover, despite the constraints of the perspectives format, I think we were very
careful with our wording to avoid misleading the reader.  The reference to the IPCC, for
example, was not at all sloppy - the opposite, in fact, since it was very carefully
worded: the IPCC Synthesis Report is referred to, rather than the full TAR, and it is
quite true that there is a focus on the reconstruction of Mann et al. in the former.  As
Mike says, IPCC conclusions were based on other work too.  But I'd guess that many of
the readers of our perspective won't have read the full IPCC report, so we thought it
valid to focus on the difference between the new work and that shown in the Synthesis
Report (which more will have seen).  To do this is certainly not unfair to the IPCC.  It
would only have been unfair if we had implied that the IPCC had ignored this new work -
but of course we weren't doing that, because how could one expect the TAR to consider
work that is published a year after the TAR itself?  We were similarly careful with our
wording in our brief mention of the MWP, by saying it is "more pronounced" in Esper et
al. - this doesn't mean it is warmer than the others (and thus has no implications for
the IPCC conclusion of recent unusual warmth), rather it is pronounced because it is
followed by stronger cooling.
The second issue is our re-calibration of the reconstructions.  While it hasn't been
explicitly stated, I get the impression that this is considered by some to be a poor
thing to do.  The particular re-calibration we do has a number of effects, including
making the Mann et al. reconstruction appear more consistently at the top of the range
of alternatives.  But please let me assure you (Mike, Ray and Malcolm) that the reason
for re-calibrating the records is definitely *not* to make your record appear as an
outlier, and I hope you believe me.  Indeed, in Jones, Osborn & Briffa (2001: Science
292, 662-667) we showed various NH records *without* applying our re-calibration.
We produced our first comparison of records for an earlier Science perspectives piece in
1999 (Briffa & Osborn, 1999) and thought it would be useful to do a re-calibration to
remove some of the reasons for inter-reconstruction differences (which can be due to:
different proxy data, different statistical methods, different calibration target and
different calibration period).  The latter two reasons were removed by re-calibrating
against a common target series and over a common period.  We updated this in Briffa et
al. (2001) and acknowledged that the target series (in terms of its spatial and seasonal
definition) may not be optimal in all cases.  Indeed, it may be especially sub-optimal
for Mann et al., because their reconstruction approach combines the proxy records to
optimally reconstruct full NH, annual mean T (whereas we have selected land north of
20N, warm-season T as our target for the recalibration).  Despite this, we felt
justified in doing the recalibration because the Mann et al. series still outperformed
the others in terms of its correlation with the instrumental record over the calibration
period!  In our latest piece, we have updated the intercomparison in two ways (as well
as including new series): (i) we took the spatially-resolved gridded reconstructions of
Mann et al. and extracted only land boxes north of 20N; and (ii) we used annual, not
warm-season, temperature as the target.  The first of these (as explained by Keith and I
in an earlier e-mail, which is repeated below because it didn't get sent to all of you
firs time round) deals with all the points raised by Mike about tropical versus
extratropical differences.  I would again argue that we were not sloppy, because these
changes to our intercomparison were carefully thought out.
So that explains what we have done and why.  There is some sensitivity, clearly, to
calibration choices, which implies to me that the true uncertainty ranges are probably
larger than those estimated solely from the statistical properties of calibration
residuals (as used by Briffa et al., and [I think] by Mann et al.).  There is clearly
more progress to be made!
Best regards to you all
Tim
------------------------------------------
Date: Fri, 05 Apr 2002 17:17:55 +0100
To: "Michael E. Mann"
,p.jones@uea.ac.uk,
tcrowley@duke.edu,rbradley@geo.umass.edu,mhughes@ltrr.arizona.edu,
drdendro@ldeo.columbia.edu,rkerr@aaas.org,bhanson@aaas.org
From: Keith Briffa
Subject: Re: Briffa & Osborn piece
Cc: Tim Osborn
Dear Mike, (and interested colleagues)
Given the list of people to whom you have chosen to circulate your message(s), we
thought we should make a short, somewhat formal, response here.  I am happy to reserve
my informal response until we are face to face! We did not respond earlier because we
had more pressing tasks to deal with. This is not the place to go into a long or
over-detailed response to all of your comments but a few brief remarks might help to
clear up a couple of misconceptions.
You consider our commentary on Ed and Jan's paper
"more flawed than even the paper itself"
on the basis that scaling the relationship between full Northern Hemisphere and
extratropical Northern Hemisphere is *much* more problematic than even any of the
seasonal issues we discuss.  In fact we did not do this.  The curve labelled Mann99 in
our figure was, in fact, based on the average of only the land areas, north of 20
degrees N, extracted from your spatially-resolved reconstructions.  We then scaled it by
calibration against the instrumental annual temperatures from the same region.  This is,
just as you stress in your comments on the Esper et al. paper, what should have been
done.  We think that this single point addresses virtually of all your concerns.  We
can, of course, argue about what this means for the pre-1400 part of your
reconstruction, when only 1 EOF was reconstructed, but the essential message is that we
did our best to exclude the tropics (and the oceans too!) from your series so that it
could more readily be compared with the other records.
The fact that we have used only the extra-tropical land from your data is not clear from
the text, so we can see why you may not have appreciated this, but we think you will
concede that this fact negates much of what you say and that we acted "more correctly"
than you realised.  Blame *Science* for being so mean with their space allocation if you
want!  Remember that this was an unrefereed piece and we felt justified in concentrating
on one issue; that of the importance of the method of scaling and its effect on apparent
"absolute" reconstruction levels.  In our draft, we went on to say that this was crucial
for issues of simple model sensitivity studies and climate detection, citing the work of
Tom Crowley and Myles Allen, but this fell foul of the editor's knife.
You also express concerns about the calibration of Esper et al. (e.g., you say "if the
authors had instead used the actual (unsmoothed) instrumental record for the
extratropical northern hemisphere to scale their record, their reconstruction would be
much closer to MBH99").
This point is wholly consistent with our discussion in the perspective piece, and indeed
we show that in absolute terms the records are closer when Esper et al. is calibrated
using unsmoothed data  but since the variance is also reduced, the significance of the
differences may be just as high.
Finally, we have to say that we do not feel constrained in what we say to the media or
write in the scientific or popular press, by what the sceptics will say or do with our
results.  We can only strive to do our best and address the issues honestly.  Some
"sceptics" have their own dishonest agenda - we have no doubt of that.  If you believe
that I, or Tim, have any other objective but to be open and honest about the
uncertainties in the climate change debate, then I am disappointed in you also.
Best regards
Keith (and Tim)
------------------------------------------
Dr Timothy J Osborn                 | phone:    +44 1603 592089
Senior Research Associate           | fax:      +44 1603 507784
Climatic Research Unit              | e-mail:   t.osborn@uea.ac.uk
School of Environmental Sciences    | web-site:
University of East Anglia __________|   [1]~timo/
Norwich  NR4 7TJ         | sunclock:
UK                       |   [2]~timo/sunclock.htm
_______________________________________________________________________
Professor Michael E. Mann
Department of Environmental Sciences, Clark Hall
University of Virginia
Charlottesville, VA 22903
_______________________________________________________________________
e-mail: mann@virginia.edu   Phone: (434) 924-7770   FAX: (434) 982-2137
[3]
References
1. ~timo/
2. ~timo/sunclock.htm
3.
4.


Dear all,
well, the time zone may let you have the last word before the weekend, but we can get the
first word in on a Monday morning!
At 22:35 12/04/02, Michael E. Mann wrote:
In keeping w/ the spirit of Tom's and Keith's emails, I wanted to stress, before we all
break for the weekend, that this is ultimately about the science, its not personal. If
my comments seemed to assail e.g. Keith's motives or integrity, etc. I believe that they
were misunderstood (as  I tried to clarify that in my previous message), but I can see
that there was a potential for misunderstanding of my message (precision in wording is
very important) given the high levels of sensitivity in this debate. So I wanted to
leave no uncertainty about that. And of course, I very much apologize to Keith (and Tim)
if they took them my comments that way. They, again, were most decidedly not intended
that way.
Thanks for clarifying that, Mike.  I think that both Keith and I interpreted your earlier
e-mail as being more critical of us than you actually meant it to be.
Most issues surrounding the recent Esper et al. and Briffa & Osborn pieces seem to have
been covered adequately already.  There are just a couple of issues on which I'd like to
add a few comments, hopefully clarifying the situation rather than opening up more avenues
for debate.
The first relates to the purpose and style of the Briffa & Osborn piece.  Perspectives are
brief, non-technical and not peer-reviewed.  Our instructions were: "The Perspective should
provide an overview of recent research in the field and explain to the general reader why
the work is particularly exciting."  Is it any surprise then that we should focus on the
new insights provided by the Esper et al. work, and that it suggests a different climate
history than earlier work?  And that the constraints of the perspectives format (in terms
of length, audience and style) prevented us from listing ALL the caveats and uncertainties
related to this and earlier reconstructions and that might be of relevance to their
intercomparison?  I don't think it is surprising, nor do I think we should be criticised
for it.
Moreover, despite the constraints of the perspectives format, I think we were very careful
with our wording to avoid misleading the reader.  The reference to the IPCC, for example,
was not at all sloppy - the opposite, in fact, since it was very carefully worded: the IPCC
Synthesis Report is referred to, rather than the full TAR, and it is quite true that there
is a focus on the reconstruction of Mann et al. in the former.  As Mike says, IPCC
conclusions were based on other work too.  But I'd guess that many of the readers of our
perspective won't have read the full IPCC report, so we thought it valid to focus on the
difference between the new work and that shown in the Synthesis Report (which more will
have seen).  To do this is certainly not unfair to the IPCC.  It would only have been
unfair if we had implied that the IPCC had ignored this new work - but of course we weren't
doing that, because how could one expect the TAR to consider work that is published a year
after the TAR itself?  We were similarly careful with our wording in our brief mention of
the MWP, by saying it is "more pronounced" in Esper et al. - this doesn't mean it is warmer
than the others (and thus has no implications for the IPCC conclusion of recent unusual
warmth), rather it is pronounced because it is followed by stronger cooling.
The second issue is our re-calibration of the reconstructions.  While it hasn't been
explicitly stated, I get the impression that this is considered by some to be a poor thing
to do.  The particular re-calibration we do has a number of effects, including making the
Mann et al. reconstruction appear more consistently at the top of the range of
alternatives.  But please let me assure you (Mike, Ray and Malcolm) that the reason for
re-calibrating the records is definitely *not* to make your record appear as an outlier,
and I hope you believe me.  Indeed, in Jones, Osborn & Briffa (2001: Science 292, 662-667)
we showed various NH records *without* applying our re-calibration.
We produced our first comparison of records for an earlier Science perspectives piece in
1999 (Briffa & Osborn, 1999) and thought it would be useful to do a re-calibration to
remove some of the reasons for inter-reconstruction differences (which can be due to:
different proxy data, different statistical methods, different calibration target and
different calibration period).  The latter two reasons were removed by re-calibrating
against a common target series and over a common period.  We updated this in Briffa et al.
(2001) and acknowledged that the target series (in terms of its spatial and seasonal
definition) may not be optimal in all cases.  Indeed, it may be especially sub-optimal for
Mann et al., because their reconstruction approach combines the proxy records to optimally
reconstruct full NH, annual mean T (whereas we have selected land north of 20N, warm-season
T as our target for the recalibration).  Despite this, we felt justified in doing the
recalibration because the Mann et al. series still outperformed the others in terms of its
correlation with the instrumental record over the calibration period!  In our latest piece,
we have updated the intercomparison in two ways (as well as including new series): (i) we
took the spatially-resolved gridded reconstructions of Mann et al. and extracted only land
boxes north of 20N; and (ii) we used annual, not warm-season, temperature as the target.
The first of these (as explained by Keith and I in an earlier e-mail, which is repeated
below because it didn't get sent to all of you firs time round) deals with all the points
raised by Mike about tropical versus extratropical differences.  I would again argue that
we were not sloppy, because these changes to our intercomparison were carefully thought
out.
So that explains what we have done and why.  There is some sensitivity, clearly, to
calibration choices, which implies to me that the true uncertainty ranges are probably
larger than those estimated solely from the statistical properties of calibration residuals
(as used by Briffa et al., and [I think] by Mann et al.).  There is clearly more progress
to be made!
Best regards to you all
Tim
------------------------------------------
Date: Fri, 05 Apr 2002 17:17:55 +0100
To: "Michael E. Mann"
,p.jones@uea.ac.uk,
tcrowley@duke.edu,rbradley@geo.umass.edu,mhughes@ltrr.arizona.edu,
drdendro@ldeo.columbia.edu,rkerr@aaas.org,bhanson@aaas.org
From: Keith Briffa
Subject: Re: Briffa & Osborn piece
Cc: Tim Osborn
Dear Mike, (and interested colleagues)
Given the list of people to whom you have chosen to circulate your message(s), we
thought we should make a short, somewhat formal, response here.  I am happy to reserve
my informal response until we are face to face! We did not respond earlier because we
had more pressing tasks to deal with. This is not the place to go into a long or
over-detailed response to all of your comments but a few brief remarks might help to
clear up a couple of misconceptions.
You consider our commentary on Ed and Jan's paper
"more flawed than even the paper itself"
on the basis that scaling the relationship between full Northern Hemisphere and
extratropical Northern Hemisphere is *much* more problematic than even any of the
seasonal issues we discuss.  In fact we did not do this.  The curve labelled Mann99 in
our figure was, in fact, based on the average of only the land areas, north of 20
degrees N, extracted from your spatially-resolved reconstructions.  We then scaled it by
calibration against the instrumental annual temperatures from the same region.  This is,
just as you stress in your comments on the Esper et al. paper, what should have been
done.  We think that this single point addresses virtually of all your concerns.  We
can, of course, argue about what this means for the pre-1400 part of your
reconstruction, when only 1 EOF was reconstructed, but the essential message is that we
did our best to exclude the tropics (and the oceans too!) from your series so that it
could more readily be compared with the other records.
The fact that we have used only the extra-tropical land from your data is not clear from
the text, so we can see why you may not have appreciated this, but we think you will
concede that this fact negates much of what you say and that we acted "more correctly"
than you realised.  Blame *Science* for being so mean with their space allocation if you
want!  Remember that this was an unrefereed piece and we felt justified in concentrating
on one issue; that of the importance of the method of scaling and its effect on apparent
"absolute" reconstruction levels.  In our draft, we went on to say that this was crucial
for issues of simple model sensitivity studies and climate detection, citing the work of
Tom Crowley and Myles Allen, but this fell foul of the editor's knife.
You also express concerns about the calibration of Esper et al. (e.g., you say "if the
authors had instead used the actual (unsmoothed) instrumental record for the
extratropical northern hemisphere to scale their record, their reconstruction would be
much closer to MBH99").
This point is wholly consistent with our discussion in the perspective piece, and indeed
we show that in absolute terms the records are closer when Esper et al. is calibrated
using unsmoothed data  but since the variance is also reduced, the significance of the
differences may be just as high.
Finally, we have to say that we do not feel constrained in what we say to the media or
write in the scientific or popular press, by what the sceptics will say or do with our
results.  We can only strive to do our best and address the issues honestly.  Some
"sceptics" have their own dishonest agenda - we have no doubt of that.  If you believe
that I, or Tim, have any other objective but to be open and honest about the
uncertainties in the climate change debate, then I am disappointed in you also.
Best regards
Keith (and Tim)
------------------------------------------


Phil,
I can't quite see what all the fuss is about Watson - why should he be re-nominated
anyway?  Why should not an Indian scientist chair IPCC?  One could argue the CC issue is
more important for the South than for the North.  Watson has perhaps thrown his weight
about too much in the past.  The science is well covered by Susan Solomon in WGI, so why
not get an engineer/economist since many of the issues now raised by CC are more to do with
energy and money, than natural science.
If the issue is that Exxon have lobbied and pressured Bush, then OK, this is regrettable
but to be honest is anyone really surprised?  All these decisions about IPCC chairs and
co-chairs are deeply political (witness DEFRA's support of Martin Parry for getting the
WGII nomination).
Mike
At 07:17 20/04/02 +0100, you wrote:
There is more on the BBC Sci/Tech web site.
Phil
Date: Fri, 19 Apr 2002 18:24:58 -0600
From: Tom Wigley
X-Mailer: Mozilla 4.76 [en] (Windows NT 5.0; U)
X-Accept-Language: en
To: Phil Jones
, Sarah Raper
,
Mike Hulme
Subject: [Fwd: SSI Alert: IPCC Chair Vote]
You may not have seen this latest piece of politicalization by the
Bushies.
Tom.
*************************
-------- Original Message --------
Subject: SSI Alert: IPCC Chair Vote
Date: Fri, 19 Apr 2002 18:00:59 -0400
From: "SSI Mailbox"
*******************  EXECUTIVE SUMMARY  ********************
ISSUE: Today - April 19, 2002, the Intergovernmental Panel
on Climate Change (IPCC) plenary voted for Dr. Rajendra
Pachauri as the sole chair of the IPCC. Dr. Pachauri, an
economist and engineer, will replace Dr. Robert Watson, an
atmospheric chemist, as chair of the IPCC. This outcome was
actively sought by the Bush Administration at the behest of
the most conservative elements of the fossil fuel industry.
This development threatens to undermine the scientific
credibility and integrity of the IPCC and may weaken the job
this extraordinary body has done to bring the world's
attention to one of the most pressing environmental
problems.
ACTION: Monitor your local paper and respond to news stories
with a letter-to-the-editor.
MAIN MESSAGE: Given the Bush Administration's consistent
opposition to climate change mitigation, it is especially
imperative at this time that the scientific community and
Dr. Pachauri work together to ensure that the IPCC remains a
strong and credible scientific process.
DEADLINE: As soon as possible after the story runs in your
paper -- preferably the same day but no later than a day or
two after.
******************************************
*** THE ISSUE ***
According to a report by Associated Press today (appended
below), Dr. Rajendra Pachauri was elected as Chair of the
IPCC at a plenary meeting in Geneva. As you would be aware
from our earlier SSI alerts of the past several weeks, this
follows on from intense lobbying of the US government by the
fossil fuel industry to remove Dr. Robert Watson as Chair.
Although reports from Geneva are still sketchy, our sources
on the ground tell us that there was intense behind-the-
scenes lobbying by Saudi Arabia, with assistance from Don
Pearlman -- a well known oil and gas lobbyist with strong
connections to industry-backed organizations opposed to
climate change mitigation. Through their maneuvering, the
co-chair compromise approach -- comprised of former chair
Dr. Robert Watson and Dr. Pachauri -- was not considered.
As a result of this election, there is considerable concern
in the climate science and environmental communities --
reinforced by the intensive lobbying from fossil fuel
interests on this decision -- that the Bush Administration's
lack of support for former IPCC Chair Dr. Robert Watson
signals a more general lack of support for the IPCC as a
credible international scientific assessment process that
provides governments with sound information on climate
science, impacts, and solutions.
By supporting Dr. Pachauri for primarily political purposes,
the Bush Administration has seriously threatened the
scientific credibility of the IPCC process. The conservative
fossil fuel interests should be exposed for their role in
influencing the US government's stance on this issue, and
the IPCC process must remain a scientifically credible and
non-politicized process.
The next IPCC Climate Change Assessment is due out in five
years, and it is the chair's role to oversee this complex
process. The scientific community's voice is important in
this issue to ensure that the IPCC process remains strong
under the leadership of Dr. Pachauri and that the Bush
Administration does not erode the effectiveness of this
important international body.
*** THE ACTION ***
-- Monitor your local paper and respond to news stories with
a letter-to-the-editor.
Information on how and to whom to submit a LTE is usually
found right on the Letters Page in your paper. Many papers
now accept letters via email. If you can't find the
information you need, simply call the paper and ask how to
go about submitting a letter in response to a recently
published article.
To increase the chances that your letter will be published,
do the following:
- keep it under 200 words and stay focused on one or two
main points you'd like to make;
- focus on a local angle, if possible, that adds something
new to the story that appeared in your paper;
- be sure to include your name, address, and daytime phone
number; the paper will contact you before printing your
letter; and
- submit the letter on the same day the story appears, if
possible.
[For additional help with writing an effective letter to the
editor, you may turn to the reference guide on the SSI
member page at
.]
-- MAIN MESSAGE: Given the Bush Administration's consistent
opposition to climate change mitigation, it is especially
imperative at this time that the scientific community and
Dr. Pachauri work together to ensure that the IPCC remains a
strong and credible scientific process.
-- TIMING: Your letter to the editor should reach your paper
within a few days of the publication of the story to
increase the chances of it being published.
-- SPECIAL NOTE: If your paper did not carry the story at
all yet, send an LTE describing the story and emphasizing
that this issue is of great interest to the paper's
subscribers.
*** SUPPORTING MESSAGES ***
-- [Be sure to include a description of your scientific
expertise, your involvement with the IPCC process, or the
importance of the climate issue to your community.]
-- For the past 10 years, the IPCC's science has been the
foundation for sound policymaking on the climate issue. The
IPCC's unique intergovernmental approach to scientific
consensus has worked amazingly well but is now threatened.
-- It is disturbing that the Bush Administration sought and
received advice from the fossil fuel industry on the
leadership of an important scientific body such as the IPCC.
A politicized IPCC threatens the integrity and credibility
of the scientific process.
-- There are fears that it will now be easier for the US to
distance itself from the IPCC process. You may point out
that the US already rejected the Kyoto protocol last year.
-- It is vital that the scientific process for the next
Assessment Report (due out in another five years) not be
compromised so that the IPCC continues to produce sound
science on climate change.
-- The credibility of the IPCC's Third Assessment Report
(TAR) findings were strongly affirmed by the US National
Academy of Sciences (NAS), which published its supportive
report in response to President Bush's request for an
independent assessment on the state of climate science.
*** SUPPLEMENTAL INFORMATION ***
-- Dr Rajendra K. Pachauri is an Indian engineer and
economist. Pachauri, formerly one of the five vice chairs of
the IPCC, is highly regarded but will be the first non-
atmospheric chemist as chair of the IPCC.
-- For more information on the ExxonMobil memo urging the
Bush Administration to remove Dr. Watson from his position
as IPCC Chair, please see
.
-- For information on the Saudi/Pearlman connection, see the
summary by Jeremy Leggett, author of "The Carbon War", at
.
-- IPCC - Intergovernmental Panel on Climate Change: The
Intergovernmental Panel on Climate Change (IPCC) was
established in 1988 under the auspices of the United Nations
Environment Programme and the World Meteorological
Organization for the purpose of assessing "the scientific,
technical and socioeconomic information relevant for the
understanding of the risk of human-induced climate change."
To date, the IPCC has issued three comprehensive
assessments. The first assessment report (FAR) was released
in 1990, the second assessment report (SAR) was released in
1996, and the third assessment report (TAR) was released in
2001. These assessments are based on "published and peer
reviewed scientific technical literature"
For more information see
******************
NOTE: Please send us an email message that tells us what
action you took. If you actually send a letter, please send
us a "blind copy." (A blind copy simply means that you do
not indicate anywhere on your letter that you are sending a
copy to us.) Send to: ssi@ucsusa.org or UCS, 2 Brattle
Square, Cambridge, MA 02238-9105 (attn. Jason Mathers).
CHANGE OF EMAIL ADDRESS: Help us keep you posted! If your
email address will soon change, or if you'd like us to use a
different address, please let us know by sending a message
to ssi@ucsusa.org with your new address. Thanks!
***********
Associated Press
Fri Apr 19, 1:18 PM ET
U.S. scientist voted off international climate panel
By JONATHAN FOWLER, Associated Press Writer
GENEVA - A U.S. scientist was voted off an international
climate panel Friday following what campaigners claimed was
pressure from the oil industry and Washington.
Atmospheric scientist Robert Watson was seeking re-election
as head of the Intergovernmental Panel on Climate Change.
World Meteorological Organization (news - web sites)
spokeswoman Mo Lagarde said Watson was defeated by Indian
challenger Rajendra Pachauri. Some 76 countries supported
Pachauri, while 49 voted for Watson in the secret ballot,
she said.
Seven nations voted for Jose Goldemberg, a Brazilian (news -
web sites) who entered the race this week.
The WMO and the U.N. Environment Program jointly host the
IPCC's offices and organized the Geneva meeting.
Environmental groups have accused the administration of
President George W. Bush (news - web sites) of caving in to
a request from Exxon Mobil that it try to remove Watson, a
leading expert on global warming (news - web sites), because
he had consistently warned governments of the dangers of
climate change.
"The fossil fuel industry and the U.S. government will be
celebrating their success in kicking out Bob Watson, an
experienced scientist who understood that urgent action is
needed to tackle global climate change," said Kate Hampton,
international climate co-ordinator for British-based Friends
of the Earth (news - web sites). "The Bush administration
and its friends would rather shoot the messenger than listen
to the message," Hampton said in a statement.
The Swiss-based Worldwide Fund for Nature said it was
worried by the "apparent politicization" of the IPCC.
"WWF is concerned that oil and gas interests had too much to
say in the removal of Dr. Watson as chairman of what should
be an impartial, scientific body," said Jennifer Morgan,
Director of WWF's Climate Program.
But, Morgan said, the "IPCC is a vibrant group of scientists
and WWF looks forward to working closely with Dr. Pachauri
to protect the integrity of the IPCC and ensure that it
continues to produce sound science on climate change."
The U.S. State Department said earlier this month that it
would support Pachauri, who was the Indian government's
nominee, to become the next chair.
Two weeks ago, the Natural Resources Defense Council, a
Washington, D.C.-based environmental group, said the White
House's Council on Environmental Quality received a memo
from Exxon Mobil in February 2001 that asked, "Can Watson be
replaced now at the request of the U.S.?"
The memo, which the group said it obtained through the
Freedom of Information Act, also recommended that the
administration "restructure the U.S. attendance at upcoming
IPCC meetings to assure none of the Clinton/Gore proponents
are involved in any decisional activities."
U.S. officials were unavailable for comment.
Watson has been an outspoken proponent of the idea that
fossil fuel emissions contribute to rising global
temperatures. He has led the panel since 1996 and is also
the chief scientist of the World Bank (news - web sites).
Pachauri is an engineer and an economist and is the director
of the Tata Energy Research Institute in New Delhi, India.
Prof. Phil Jones
Climatic Research Unit        Telephone +44 (0) 1603 592090
School of Environmental Sciences    Fax +44 (0) 1603 507784
University of East Anglia
Norwich                          Email    p.jones@uea.ac.uk
NR4 7TJ
UK
----------------------------------------------------------------------------
References
1.
2.
3.
4.


Simon,
A version of this for In Tyndall please - you should add the relevant EPSRC web site if you
can track it down.
Mike
_________________________________
EPSRC invests in adventurous ideas
EPSRC is to establish an adventurous research fund. A total of £4.5 million has been
earmarked for research projects that include a mixture of disciplines and as such may face
barriers to selection under EPSRCs core research programmes. The pilot initiative will be
launched with a call for outline proposals at the end of May. The closing date will be at
end
of July. Those successful at the outline stage will be asked to submit full proposals by
December. The new funds principal novelty is an emphasis on funding people to work in
other disciplines or between disciplines. EPSRC will fund any research project that falls
within its centre of gravity. We are happy for it to be 49 per cent in another research
council remit, so long as the majority is in the EPSRC remit, says Hylton. Equally, EPSRC
has not capped how much money people can apply for. Another key difference is the way in
which the proposals will be evaluated. It will be a two-stage process with outline
proposals
followed by full proposals. The outline stages of applying to the adventure fund are to be
assessed anonymously. In addition, the initiative will have its own bespoke outline
application form, proposal form and referees assessment form. EPSRC also hopes the
initiative will go some way to changing UK research culture.


Hi Keith,
Of course, I agree with you. We both know the probable flaws in
Mike's recon, particularly as it relates to the tropical stuff. Your
response is also why I chose not to read the published version of his
letter. It would be too aggravating. The only way to deal with this
whole issue is to show in a detailed study that his estimates are
clearly deficient in multi-centennial power, something that you
actually did in your Perspectives piece, even if it was not clearly
stated because of editorial cuts. It is puzzling to me that a guy as
bright as Mike would be so unwilling to evaluate his own work a bit
more objectively.
Ed
>I have just read this lettter - and I think it is crap. I am sick to
>death of Mann stating his reconstruction represents the tropical
>area just because it contains a few (poorly temperature
>representative ) tropical series. He is just as capable of
>regressing these data again any other "target" series , such as the
>increasing trend of self-opinionated verbage he has produced over
>the last few years , and ...  (better say no more)
>Keith
>
--
==================================
Dr. Edward R. Cook
Doherty Senior Scholar
Tree-Ring Laboratory
Lamont-Doherty Earth Observatory
Palisades, New York 10964  USA
Email:	drdendro@ldeo.columbia.edu
Phone:	845-365-8618
Fax:	845-365-8152
==================================


Mike,
Checked with Keith and Tim.  The abstract is like one we would write - leaves all
options
open as to what will be presented.  At least AGU and EGS don't charge to get abstracts
printed. AMS have so many missing now with their charges that the book of abstracts is
ridiculous.  Fine for all three of us to be there and we look forward to seeing some
results
in the autumn. This will be when the real action begins.
The CCDD meeting in early Nov. might be at a good time to discuss some results.
Add an 'of'  between choice and actual on the third line.
Cheers
Phil
At 19:56 12/08/02 -0400, Michael E. Mann wrote:
Dear all,
The following is an abstract for a talk I've been invited to give at the winter AGU
meeting in a session on "Climate of the Past 2000 Years". I would like to summarize the
collaborative work that was begun by Scott, Tim and myself a couple summers ago during
Tim's visit here. Scott is working on finalizing the results of our analyses now, and a
draft should be available for review shortly that compares reconstructions based on our
covariance-based reconstruction method, using (i)  multiproxy, (ii) MXD, and (ii)
combined multiproxy+MXD datasets for different (cold, warm, annual) target seasonal
windows.   I'd like to invite everyone listed below to be authors on both this abstract,
and the paper that we're in the process of drafting, describing the results. I've kept
the abstract intentionally vague, so that we can work out an interpretation of the
results that we're all comfortable with in the months ahead, prior to the talk, and
submission of the paper.
I look forward to confirmation of your interest in being a co-author, and any  feedback
you have. I'd like to submit this by the end of the week, which will be my last
opportunity to do so prior to the AGU abstract deadline, owing to my travel schedule.
thanks in advance for getting back to me ASAP.
best regards,
Mike
_____________________________________________________________________________
Progress in Proxy-Based Reconstruction of Surface Temperature Variations in Past
Centuries
Michael E. Mann
Raymond Bradley
Keith Briffa
Malcolm Hughes
Philip Jones
Timothy Osborn
Scott Rutherford
Results are presented from a set experiments designed to control for the various factors
that may influence reconstructions of large-scale temperature patterns in past
centuries,  including (a) the choice actual proxy data used, (b) the reconstruction
methodology, (c) the spatial domain of the reconstruction and (d) the seasonal window
targeted. These experiments compare results based both on the global multiproxy data set
used by Mann and coworkers and the extratropical Northern Hemisphere maximum latewood
tree-ring density set used by Briffa and coworkers. Estimates of hemispheric mean
temperature trends are formed both through averaging of   large-scale patterns
reconstructed from full proxy data network, and through simple compositing of regional
temperature reconstructions. Northern hemisphere mean estimates are compared for the
full Northern hemisphere (tropics and extratropics, land and ocean), and extratropical
continents only, and using various (cold-season half year, warm-season half year, and
annual mean) seasonal targets for the reconstructions. Implications of these experiments
for the robustness of proxy-based reconstructions of past large-scale temperature trends
are discussed.
_______________________________________________________________________
Professor Michael E. Mann
Department of Environmental Sciences, Clark Hall
University of Virginia
Charlottesville, VA 22903
_______________________________________________________________________
e-mail: mann@virginia.edu   Phone: (434) 924-7770   FAX: (434) 982-2137
[1]
Prof. Phil Jones
Climatic Research Unit        Telephone +44 (0) 1603 592090
School of Environmental Sciences    Fax +44 (0) 1603 507784
University of East Anglia
Norwich                          Email    p.jones@uea.ac.uk
NR4 7TJ
UK
----------------------------------------------------------------------------
References
1.


Dear Keith,
thank you very much for editing our paper.
It's a pity you strike your name off the list of authors, you
make an important contribution to writing paper. Your corrections
and additions surely improve paper.
I would only notice the next sentence (page 8):
'The low interannual variability and the minimum occurrence of
cold extremes during the 20th century, argue that the most recent
decades of this long summer record represent the most favourable
climate conditions for tree growth within the last four
millennia.'
I'm not sure that this statement follows unambiguous from results
presented in this paper. Because mean temperatures during last
decades, according presented reconstruction, are not exceptional.
Besides, e.g. period about 1700 BC, according this
reconstruction, represent probably the same conditions taking
into account low variability, low occurrence of extremes and high
mean temperature.
May be to soften this statement and replace 'the most favourable'
with something like 'highly favourably' or 'probably the most
favourable'?
Thank you once more for invaluable assistance.
Best regards,
Rashit M. Hantemirov
(I'm sorry for the late answer, I just come back from the trip to
the north.)
Lab. of Dendrochronology
Institute of Plant and Animal Ecology
8 Marta St., 202
Ekaterinburg, 620144, Russia
e-mail: rashit@ipae.uran.ru
Fax: +7 (3432) 29 41 61; phone: +7 (3432) 29 40 92
#3


Iain (and Geoff),
Definitive explanations are always dangerous!  The reasoning behind this is as follows:
- the report only analysed and pictured seasonal and annual data (DJF,MAM, etc.) [in fact,
nearly all published maps of climate model outputs show changes in seasonal - 3-month -
averages].  This applying a uniform filter over 90 or 360 days.
- the requested datasets are at monthly time-steps.  The default option for this is in
effect applying a uniform 30-day filter.  [one might also conceive of weekly or daily
time-step files - e.g. changes in Week 13 for the 2050s for precip. for Medium-High or
changes for Julian day number 256 for the 2080s for Tmin for Low].
- these are all arbitrary choices of course, dictated by convention.  But the important
point it seems to me is again a signal to noise issue - the shorter the time-averaging
period, the weaker the S/N ratio [i.e., we have more confidence that averaged over a year,
Tmin in the UK will increase by, say, 2.7degC for certain scenario, than that for the same
scenarios Tmin on 13 June will increase - on average - by 2.6degC and on 14 June only by
2.3degC - is this difference between 2.6 on 13 June and 2.3 on 14 June really meaningful?
No - it is most likely due to noise - natural variability].
- this reasoning suggests that as the time-averaging period decreases, one should pay less
attention to small differences between adjacent time-averaged periods, e.g. if June precip.
goes down by 10%, is the fact that July precip. goes down by 20% and August by 5% really
meaningful?
-
At 10:13 11/09/02 +0100, Iain Brown (UKCIP) wrote:
Mike,
For the UKCIP Scenarios datasets - both 98 and 02 - temporal interpolation
was applied to the raw model data in the form of a 1-2-1 filter. This had
the effect of smoothing out monthly values so that there are not as abrupt
transitions between adjacent months.
Can you provide us with the definitive explanation for the interpolation?
Some users (eg. in the recent London study) have noted that there are
differences between the maps they have derived from the data and the maps in
the UKCIP02 report.
best wishes,
Iain
-----------------------------------
Dr. Iain Brown
UK Climate Impacts Programme
12 St. Michael's St.
Oxford
OX1 2DU


Gareth,
It seems to me, from reading your email, that you do not realize that
this is precisely what MAGICC/SCENGEN already does -- i.e., it uses the
scaling method that Ben Santer and I 'invented' in the late 1980s to get
time dependent patterns of future climate change. I am attaching a
description of the method as we employ it.
The current CDROM version uses only a SAR version of the UD-EBM. Of
course, there is a TAR version that Sarah used for the TAR, developed by
me and Sarah -- but mainly Sarah. This has not yet been put into
MAGICC/SCENGEN, although I am in the process of doing so (along with
making a number of other changes to the software). We do not normally
give the code for TAR/MAGICC to others unless it is as part of a
collaborative project. As Mike Hulme noted, what we can do for/with you
will have to be a joint decision with me and Sarah.
The issue of how well scaling works compared with a full AOGCM is both
important and of considerable interest to me (and Ben Santer). It is
something we have looked at in the past, cursorily, and which we were
planning to investigate more fully with the suite of PCM runs that we
have here. There are some tricky issues that need to be addressed.
So, perhaps we should pool our intellectual, modelling and data
resources?
Anyhow, check out the attached and get back to me with your views.
The 'new and improved version' of MAGICC/SCENGEN should be available in
beta-test form in about a month. It will have around 30 models in its
data base, and it does a lot of new things that I can tell you about
later.
Tom.
++++++++++++++++++++++++++++++++++
Mike Hulme wrote:
>
> Gareth,
>
> Thank you for endowing me with the grand title of co-ordinator of magic!!
>
> Such a position does not really exist here.  The model developers are Sarah
> Raper and Tom Wigley, to whom I am copying this reply, and it is the two of
> them that really need to grant your request.
>
> My role is more specifically in relation to the availability and
> distribution of the public domain version of MAGICC/SCENGEN Version 2.4 on
> CD-ROM and the accompanying manual.  However, your request is really for
> the TAR version of MAGICC and even the source code and that request I
> cannot grant.
>
> I would hope that either/or Sarah and Tom will reply to you directly.
>
> Best wishes,
>
> Mike
>
> At 11:54 13/09/02 +0100, you wrote:
> >Dear Dr Hulme,
> >         I believe that you are the MAGICC co-ordinator in the Climatic
> > Research
> >Unit. I hope you can assist me with the following request.
> >
> >         I would like to obtain a version of the Magicc model that would allow
> >the input of climate forcings (rather than emission scenerios).
> >
> >I am in the detection and attribution group within the Hadley Centre, Met
> >Office. I am working with Dr Peter Stott and Dr John Mitchell on a project
> >that
> >requires an EBM.
> >
> >What we want to use the EBM for is to simulate global mean temperatures for
> >different forcings which we can then multiply with equilibrium temperature
> >spatial patterns for the same forcings to create surrogate transient time
> >varying climate patterns. If the surrogate patterns compare favourably
> >with our
> >HadCM3 simulations, we will then want to investigate how the detection and
> >attribution of climate change (for the detection schemes we use) will be
> >affected by uncertainties in the forcings we use. We would like  to use
> >Magicc
> >as it has been tuned already to the HadCM3 anthropogenic emissions scenerios,
> >and as a model used extensively in the recent IPCC TAR would be most
> >appropriate
> >for our work.
> >
> >Would it be possible to obtain a copy of MAGICC or can you tell me how I
> >could
> >go about obtaining the model?
> >
> >Thanks in advance
> >Gareth
> >
> >--
> >Dr Gareth S. Jones      Climate Research Scientist
> >Met Office, Hadley Centre for Climate Prediction and Research,
> >London Road, Bracknell, RG12 2SY, UK
> >Tel/Fax: +44(0)1344 85 6903/4898 email:gareth.s.jones@metoffice.comContent-Type: x-msword;
name="MAG-SG.doc"
Content-Disposition: inline;
filename="MAG-SG.doc"
Attachment Converted: "c:\eudora\attach\MAG-SG1.doc"
Content-Type: x-msword;
name="SGFlowchart.doc"
Content-Disposition: inline;
filename="SGFlowchart.doc"
Attachment Converted: "c:\eudora\attach\SGFlowchart1.doc"


Dear member of the extended board
The next ECF telephone conference takes place on Monday, 7 October 2002 at
17-18 CET (Central European Time). The participants are:
Gerhard Berz 089-3891 5290
Carlo Carraro +39-335-6170 775
Baldur Eliasson +41-58-586-8031
Jürgen Engelhard 0221-480 1460
Bill Hare 0331-288 2412
Klaus Hasselmann 04121-508 849
Jean-Charles Hourcade +33-1-43 94 73 63
Mike Hulme +44-1603-593162
Stephan Singer +32-2-74 38817
Carlo Jaeger 0331-288 2601
Martin Welp 0331-288 2619
Please check that your number is correct. If you want to be called at
another number please inform me by the end of this week. In case there are
technical problems at the beginning or during the conference please call
the Deutsche Telekom at +49-(0)69-90922723.
The agenda is as follows (it may be modified at the beginning of the meeting):
1 Minutes of the previous telephone conference (5 Min.)
2 Working groups (10 Min.)
3 Meetings & Events (15 Min.)
- Report of the meeting with IEA (International Energy Agency)
- Report of the meeting with Vivendi Environnement Institute
- ECF general assembly (13 November)
- ECF conference in Berlin (14-15 November)
- Workshop of the Technology Group in Oldenburg (12-13 December)
4 Next steps (15 Min.)
5 Varia (15 Min.)
Best regards,
Martin Welp
--
NOTE NEW FAX NUMBER
Dr. Martin Welp
Potsdam Institute for Climate Impact Research (PIK)
Dept. Global Change and Social Systems
P.O. Box 601203, 14412 Potsdam, Germany
Tel. +49 331 288 2619
Fax +49 331 288 2640
E-mail: martin.welp@pik-potsdam.de
Internet:
~welp/index.html


I am forwarding this to stimulate you (no it's not one of those emails!) to
hassle me to check and update the tree-ring and my stuff on the web. Cheers
Keith
Date: Thu, 10 Oct 2002 11:22:37 -0400
From: Leonid Polyak
Subject: Re: Polar Urals data
X-Sender: lpolyak@pop.service.ohio-state.edu
To: Keith Briffa
X-Mailer: QUALCOMM Windows Eudora Pro Version 3.0.3 (32)
Got it! Note that there appears to be an error in the explanation for the
data file: Polar Ural data are f2, not f1 (as far as I can judge).
Thank you,
Leonid
>
>Leonid
>see [1]
>The data (and other possibly interesting data are available there) .
>Best wishes
>Keith
--
Professor Keith Briffa,
Climatic Research Unit
University of East Anglia
Norwich, NR4 7TJ, U.K.
Phone: +44-1603-593909
Fax: +44-1603-507784
[2]
References
1.
2.
3.


Tom,
Talked to Tim re the SD field. Can you read the following (J. Climate
10, 2548-2568)
before you come so you know how Tim infilled the SD field ?  HadCM2 data
was used.
This would seem to bias any model validation to this model. Also it would
seem odd to
validate any model in a region where there is no data - in a region that
had to be infilled.
I can see that global fields make things simpler, but they will need
to constructed in
the best possible way. In 1997 we thought the best way was to use a
model, but our aim
then was different from yours.
Cheers
Phil
At 06:04 28/10/02 -0700, Tom Wigley wrote:
>Phil,
>
>Thanx. I need to see if CMIP has the height fields for models ---
>Ben????
>
>Tom.
>
>_______________________________
>
>Phil Jones wrote:
> >
> >   Tom,
> >      Here's the file that you should have got back in September. It is
> > 1981-2000 where this
> >   could be calculated and 1961-90 elsewhere. The other fields (already
> > sent) enable you to
> >   know where the 1961-90 field has been used.
> >      All you need to overcome the problem of this being surface
> > temperatures is to get a
> >   5 by 5 degree average height field. I have emailed Mark New to see if he
> > has a 1 by 1 degree
> >   height field, which could then be averaged. Mark must have had this at
> > some stage - he
> >   has a 10 minute height field for the world, which I'm sure he has
> > degraded to 1 degree. I
> >   have a land/sea mask at 1 by 1 degree, so am hoping Mark has the heights.
> > With this
> >   all you will need is the model height fields.
> >       As for the SD's it would be possible to produce this for a period
> > like 1981-2000 or 1961-90
> >   but both would have gaps - probably exactly the same as in the
> > climatology. The options
> >   to consider here are:
> >
> >   1. Period 1981-2000 or 1961-90?
> >   2. How many years in each needed to get an SD?
> >   3. How to infill the gaps?
> >
> >   Tim Osborn must have infilled the gaps for the errors paper in 1997 as we
> > needed a complete
> >   field of variances. He did this by blending some model data
> > (HadCM2/ECHAM3 probably)
> >   with the real observations. Most areas get infilled easily - big problem
> > is the Southern Oceans
> >   and the Antarctic (also central Arctic).  I will talk to Tim.
> >
> >   We can discuss this more when you come.
> >
> >   Cheers
> >   Phil
> >
> >   PS I should have some results from Anders by the time you come. He is
> > comparing means/
> >   SDs and extremes etc of HadRM3 with real world data from 200 sites across
> > Europe. Only
> >   temperature variables in the first part. Clearly shows that for
> > islands/coasts comparisons
> >   must be with land points in the model. We've had to 'move' some stations
> > to be on model
> >   land to get better comparisons. Islands that are not in the model have
> > poor comparisons.
> >   It is possible to see country outlines in some comparisons with either
> > max or min
> >   temperatures. Corrections for elevation are needed to get over large
> > elevational differences
> >   between stations and the model, but the Alps are still visible. Lapse
> > rates work best only
> >   in some seasons - not very good in summer. Max temps produce consistent
> > difference maps
> >   (model-obs) over Europe, but mins are more erratic/random. Min error is
> > overall small but
> >   with a large variability while max has a larger error but low
> > variability. Due to mins being more
> >   affected by local environment.
> >
> > At 09:13 27/10/02 -0700, Tom Wigley wrote:
> > >Phil,
> > >
> > >Re my last email ....
> > >
> > >I have looked at the data you sent. It would be very nice to have a
> > >gapless 1981-2000 T climatology to match the Xie/Arkin precip
> > >climatology. However, this means somehow filling in the gaps in the
> > >61-90 minus 81-00 differences, a nontrivial task. So my choice in the
> > >absence of this is either a gappy 81-00, or a full 61-90. I have chosen
> > >the latter -- perhaps we can discuss how to produce a gapless 81-00
> > >climatology when I am at CRU?
> > >
> > >A problem with the 61-90 is that it is surface, and that observed
> > >surface is not equal to model surface. I'm sure you have thought about
> > >this (in the model validation context) already, so this is another item
> > >to discuss.
> > >
> > >For precip, I also have the inter-annual S.D. climatology, so I can
> > >validate both the mean climate and the variability. Very interesting. It
> > >would be nice to be able to do this with temperature (especially since
> > >the mean climate for temperature in the models is pretty darn good --
> > >but how good is variability?) Is there an S.D. climatology for
> > >temperature that you can send me?
> > >
> > >Cheers, Tom.
> >
> > Prof. Phil Jones
> > Climatic Research Unit        Telephone +44 (0) 1603 592090
> > School of Environmental Sciences    Fax +44 (0) 1603 507784
> > University of East Anglia
> > Norwich                          Email    p.jones@uea.ac.uk
> > NR4 7TJ
> > UK
> >
> ----------------------------------------------------------------------------
> >
> >   ------------------------------------------------------------------------
> >                         Name: newabsref8100.out
> >    newabsref8100.out    Type: Plain Text (text/plain)
> >                     Encoding: base64
Prof. Phil Jones
Climatic Research Unit        Telephone +44 (0) 1603 592090
School of Environmental Sciences    Fax +44 (0) 1603 507784
University of East Anglia
Norwich                          Email    p.jones@uea.ac.uk
NR4 7TJ
UK
----------------------------------------------------------------------------


X-Sender: hegerl@mail-he.acpub.duke.edu
Date: Fri, 1 Nov 2002 09:56:45 -0500
To: Phil Jones
From: Gabi Hegerl
Subject: Re: paleo data
No worries, I can wait till next week!
It would be great to hear from you next week particularly if you
feel I have overlooked something, I am planning to submit a little
GRL paper on the detection results based on paleodata soon, and so a warning
if I am doing something wrong would be great.
Its not surprising that the detection results are stable, since other than volcanic
forcing is mainly driven by the low-f component anyway.
But it looks to me like the volcanic response is not smaller or even a bit larger in the
annual JGR data (except for one real real big peak in
the 1998 data).
Greetings, have a good weekend and good luck for Keith's back
Gabi
Gabi,
I have printed the files, but I do not know the answer. Keith is off today with a
bad back -
seeing a chiropractor. I need to talk to him before we can reply. I will be away
Mon/Tues
next week, so we will not be able to reply until later next week.
Cheers
Phil
At 11:27 31/10/02 -0500, Gabi Hegerl wrote:
Dear Keith and Phil,
I checked and found that we did indeed use the JGR 2001 data (by reloading them
from your JGR data file). I also got the
1998 data from the volcano paper, and did some checking. My detection results
appear quite unimpressed by if I filter the 2001 data to focus on lower
frequencies or not (the estimated amplitudes of solar, volcanic and ghg signals
are virtually identical, volcanism gets a bit tougher to detect if you remove
the high-frequency component).
Then I redid the Epoch analysis comparing the
response of your data old and new to volcanism, and find somewhat bigger volcanic
signals on average (using 50 eruptions between 1400 and 1940) in the
JGR paper record. I high-passed both datasets and get somewhat more variability
in the JGR record, not the 1998 record.
I am wondering is there something I am overlooking?
I append a figure of the high-passed (var > ca 10 yrs removed) records,
and the volcanic response in both datasets (averaging years 1-20 after the  eruption,
and removing the best-estimate solar and ghg signal before the analysis).
The analysis omits years with another volcanic eruption within the 20 yrs.
I also append one version of the figure where the upper 95%ile of the ghg signal (which
appears underestimated in Briffa 98 data) is removed rather than the
best estimate, in that case, the volcanic signals in both data appear nearly
identical.
Greetings, and please let me know if I am doing something wrong with your data!
Also, what is the best reference to a discussion on the difference between both
datasets?
Thanks in advance
Gabi
Dear Tom
after a little detective work we have deduced that the data sent to you constitute a
version of Northern Hemisphere Land temperatures (april- sept) produced by PCA
regression using regional average density chronologies (ie the JGR paper you refereed I
believe). It is true that high frequency component is not in my opinion optimal in
describing the relative magnitude of extreme inter-annual extremes. This is to do with
the unpredictable weighting ascribed to certain areas (tree-density series) in the
averaging of the original raw data ( this is boring and I won't go into it unless you
really want me to). Te relative differences in year-to-year values are likely better
represented in the N.Hemisphere series produced by averaging regional series produced
using a different approach in which the initial data are high-pass filtered and then
merged in a more straight forward way. This is more equivalent to the series on volcanic
signals described in our Nature paper, though the low-frequency component in this series
is definitely not represented. There is another series , that one could consider a good
compromise . That is a composite of the Age-Banding approach (JGR) low-frequency
variance added to the earlier (Nature) high-frequency component. We did this for Figure
6 in the JGR paper , but did not provide the data on our web site I now realize. However
this composite series is VERY highly correlated with the "better" high frequency data -
see the correlations (Table 1 and related text in
[1]
There are many possible ways of producing a "Northern Hemisphere" average , involving
different prior regionalisation and secondary weighting (in space and through time) of
the constituent series) . Non can be considered "correct". If you would like us to dig
out the composite series or discuss specific aspects of the logic or uncertainties
associated with the  different large averages let me know. Perhaps it would be better to
discuss this on the phone? As for longer series , we can provide  the 2000 year
N.Eurasian data (a composite of ring width chronologies in N.Sweden, The Yamal
peninsula, and Taimyr ) . I will soon be able to provide a 4000-year version , that is
now being worked on.
or a similar Northern tree-ring chronology incorporating more data eg see
[2]
We do not have the bristlecone data - but they are available I presume from the
International Tree-Ring Data bank , part of the NGDC holdings?
At 02:29 PM 10/1/02 +0100, Phil Jones wrote:
Tom,
Been away and going again tomorrow. Had a chat with Keith and Tim and one of them
will send a reply and data later this week.
Cheers
Phil
At 11:28 26/09/02 -0400, Tom Crowley wrote:
Hi Phil,
thanks for all your help on the bams paper
DOE is being exceedingly slow in processing the paperwork for our new round - I will
keep you posted.
I am also wondering whether we can get some data from you:
Gabi is comparing our 2d ebm run with the briffa et al 2001 jgr time series in order to
compare the model prediction of - I think you mentioned at one point something to the
effect that, although this series is good for estimating low resolution temperature
variability, it may dampen high frequency variability.  if my memory is correct in this
case, would you please send gabi the record you consider best for comparing with the
model predicted interannual response to volcanic eruptions?
on another matter we are extending our runs back in time - I have now compiled a record
of global volcanism back to 4000 BP for both hemispheres - extended back to 8000 BP for
30-90N.  we are therefore trying to compile paleo records older than AD 1000 to at least
get some reconstruction we can compare with.
I seem to recall that Keith or you may have published some longer reconstructionn but
cannot recall where it is?  if so, would you be so kind as to send it to me?  also I am
trying to find a long record from the eastern California for the bristlecone pine - for
some reason I am having difficulty finding one.  if you have a long record - even going
back beyond 2000 BP, it would be very much appreciated.
thanks for any help you can give us on this and best wishes, Tom
--
Thomas J. Crowley
Nicholas Professor of Earth Systems Science
Dept. of Earth and Ocean Sciences
Nicholas School of the Environment and Earth Sciences
Box 90227
103  Old Chem Building
Duke University
Durham, NC  27708
tcrowley@duke.edu
919-681-8228
919-684-5833  fax
Prof. Phil Jones
Climatic Research Unit        Telephone +44 (0) 1603 592090
School of Environmental Sciences    Fax +44 (0) 1603 507784
University of East Anglia
Norwich                          Email    p.jones@uea.ac.uk
NR4 7TJ
UK
----------------------------------------------------------------------------
--
Professor Keith Briffa,
Climatic Research Unit
University of East Anglia
Norwich, NR4 7TJ, U.K.
Phone: +44-1603-593909
Fax: +44-1603-507784
[3]
--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Gabriele Hegerl - NOTE CHANGE IN ADDRESS FORMAT
Department of Earth and Ocean Sciences,
Nicholas School for the Environment,
Box 90227
Duke University, Durham NC 27708
Ph: 919 684 6167, fax 684 5833
email: hegerl@duke.edu, [4]
Prof. Phil Jones
Climatic Research Unit        Telephone +44 (0) 1603 592090
School of Environmental Sciences    Fax +44 (0) 1603 507784
University of East Anglia
Norwich                          Email    p.jones@uea.ac.uk
NR4 7TJ
UK
----------------------------------------------------------------------------
--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Gabriele Hegerl - NOTE CHANGE IN ADDRESS FORMAT
Department of Earth and Ocean Sciences,
Nicholas School for the Environment,
Box 90227
Duke University, Durham NC 27708
Ph: 919 684 6167, fax 684 5833
email: hegerl@duke.edu, [5]
Prof. Phil Jones
Climatic Research Unit        Telephone +44 (0) 1603 592090
School of Environmental Sciences    Fax +44 (0) 1603 507784
University of East Anglia
Norwich                          Email    p.jones@uea.ac.uk
NR4 7TJ
UK
----------------------------------------------------------------------------
References
1.
2.
3.
4.
5.


The delay again is simply because I was away for 2 days. Attached are the data you want.
First number is number of years of record, followed by
(in first column) year A.D. and (in second column) the numbers you want . Ignore other
columns. Cheers
Keith
At 02:58 PM 11/5/02 -0500, you wrote:
Keith,
To keep you informed about the use of your Salekhard data, I attach the MS
which I'm submitting to The Holocene. I've referred to your papers of 1995
and 2000. If you'd like me to add more acknowledgement of your data, let me
know and I'll gladly do that.
Sincerely,
Leonid
Leonid Polyak
--------------
Byrd Polar Research Center
Ohio State University
1090 Carmack Rd., Columbus, OH 43210
614-292-2602, fax 614-292-4697
[1]
>Leonid
>see [2]
>The data (and other possibly interesting data are available there) .
>Best wishes
>Keith
--
Professor Keith Briffa,
Climatic Research Unit
University of East Anglia
Norwich, NR4 7TJ, U.K.
Phone: +44-1603-593909
Fax: +44-1603-507784
[3]
References
1.
2.
3.
4.