Paleoclimate – Rotten to the core

There is a lot to be said about Climategate 2 emails. Since I’ve focused so much of my time on dendroclimatology, much of the climate science I’ve studied is related to that subject.   This is in no small part due to the influences of Steve McIntyre at Climate Audit.  Often, we skeptics have made the point that trees are terrible thermometers and equally often I’ve wondered if these climatologists understand just how bad the hockey stick reconstructions are. When these issues are discussed here in the open, the believer groups usually stop by and claim that the multiple studies with same or similar results are somehow “verification” of their accuracy. The reality is that nothing could be further from the truth.

An important email because it comes from IPCC AR4 Lead Author Richard Alley makes many of the points we stand behind in one single email. This was brought to my attention by reader Kan – #3234. For the most part, emails are included in full in this post for correct context but critical parts have been bolded by me.  As a suggestion, you can read the post by skipping to the bold sections first and then checking the email for correct context.

date: Fri, 10 Mar 2006 22:50:43 -0500 (EST)
from:
subject: Divergence
to: drdendro@ldeo.columbia.edu, jto@u.arizona.edu, k.briffa@uea.ac.uk

Ed et al.–This is getting a little unmanageable in a hurry, I fear–there
are now two or three overlapping emailing lists active, and my original
words have been muddied. I am not on the committee, and I clearly
never said that I know what the committee is thinking or doing. I did say that
based on my impression of the questions asked in public by the committee (or more
properly, by some members of the committee…) that I felt that they had
some serious issues, and that I don’t expect that they will provide
a strong endorsement of the tree-ring based millennial reconstructions.
Rosanne did not emphasize the divergence problem, and sought to play it down
as something that might have several explanations but that did not upset
the basic reconstructions, so her presentation was in line with your emails.
She did show her data, and the folks in the meeting room saw the divergence
in those data.

Despite assurances from Ed and Keith, I must admit that I still don’t
get it. The NRC committee is looking at a number of issues, but the one
that is most publicly noted is to determine whether, and with what confidence,
we can say that recent temperatures have emerged from the band of natural
variability over the last millennium or two. Millennial reconstructions with
high time resolution are mostly tree-ring based, mostly northern
hemisphere, and as I understand it, some are correlated to mean-annual
temperatures and others to seasonal temperatures. The performance of
the tree-ring paleothermometry is central. Taking the recent instrumental
record and the tree-ring record and joining them yields a dramatic picture,
with rather high confidence that recent times are anomalously warm. Taking
strictly the tree-ring record and omitting the instrumental record yields
a less-dramatic picture and a lower confidence that the recent temperatures
are anomalous. When a big difference is evident between recent and a
millennium ago, small errors don’t matter; the more similar they are, the
more important become possible small issues regarding CO2 fertilization,
nitrogen fertilization (or ozone inhibition on the other side…).

Unless the “divergence problem” can be confidently ascribed to some cause that
was not active a millennium ago, then the comparison between tree rings from
a millennium ago and instrumental records from the last decades does not seem
to be justified, and the confidence level in the anomalous nature of the recent
warmth is lowered. This is further complicated by the possible small influence
of CO2 fertilization.

Ignoring for a moment the reasons for the controversy, the motivations of
some of the participants, the relative scientific unimportance
of the answer (this is about icons, not science), the implications if the
skeptics are actually right (the climate may be more sensitive than we thought,
because forcings are not revised if the thermometry is revised, so global
warming may be worse than we thought), and any other extraneous issues, I
believe that:

–There will be a lot of press and blog coverage of this issue when the NRC
report comes out;

–People will look closely at how the IPCC and NRC agree/disagree on this;

–There is a reasonable likelihood that the basic thrust of the IPCC and NRC
will agree, but that the details of wording and confidence may be somewhat
different, and that this difference could be amplified greatly by the
political process in ways that would be used to damage the IPCC.

For what it’s worth, I also am not fully reassured by the emails that have
come through.

Ed gives a very nice statement of what might have been done procedurally,
but none of this was done, the time for the committee is very tight (the report
is to be done by the time we meet in Norway, I believe…), and unless some
of you provide input to the committee, they probably have a large fraction of
their information already. (I believe that you can make statements to the
committee by email; statements will be posted on a public web site and used
by the committee.)

Keith says that the issues are complicated (undoubtedly correct),
that he has unpublished data making the case stronger, and that
“virtually all long tree-ring reconstructions that contribute to
the various reconstructions, are NOT affected by this. Most show good
coherence with temperature at local levels in recent decades.” I was just
looking at some of the recent Mann et al. papers, and at the
Osborn and Briffa paper from this year. In that one, as nearly as I can tell,
there are 14 long records, of which 2 extend to 2000, 8 end in the early to
mid 1990s, 1 in the early to mid 1980s, 2 in the early to mid 1970s, and one
in the late 1940s. That looks to be a pretty small data set by the time you
get into the strongest part of the instrumental warming. If some of the
records, or some other records such as Rosanne’s new ones, show “divergence”,
then I believe it casts doubt on the use of joined tree-ring/instrumental
records, and I don’t believe that I have yet heard why this interpretation is
wrong.

I’m open to hearing what I have screwed up. Please note, I have no direct
stake in this! I went to the meeting, I spoke, I’m done. But, I think you
have a problem coming, that it involves the IPCC and particularly chapter
6 and paleo generally, that I really should let
Susan know what is going on (if you’ve seen all the increasingly publicly
disseminated emails, you know the story). I’d rather go back to teaching
and research and raising money and advising students and all of that, but
I’m trying to be helpful. Casting aspersions on Rosanne, on the NRC panel, or
on me for that matter is not going to solve the underlying problem.

Regards–Richard

The points Richard makes are generally accurate although a case could be made for and against his sensitivity remarks.  That is a different topic though.  To sum up the points I’m addressing here- If we can’t explain divergence, we cannot delete the data and if we cannot delete the data we must question all of the tree data.

I think Ed Cook articulates the problem clearly in a very long email to Keith Briffa 3253.  This email was in Climategate #1 and was one of the more interesting emails to me.  What we have that is new though are replies from Keith Briffa in #0435 and #0643.  I’ve bolded the critical parts again below so you can read it more quickly but the email is included in its entirety for proper context.  From the emails I actually like Ed Cook, he’s not one to mince words and doesn’t allow outside pressures to influence his views. Here, he’s a little ticked at another scientist for being a know-it-all when they know full well that the uncertainties of hockey sticks are far greater than advertised.

date: Wed, 3 Sep 2003 08:32:11 -0400
from: Edward Cook <drdendro@ldeo.columbia.edu>
subject: An idea to pass by you
to: Keith Briffa

<x-flowed>
Hi Keith,

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Cheers,

Ed
—
==================================
Dr. Edward R. Cook
Doherty Senior Scholar and
Director, 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
==================================

Now that is quite a bombshell of an email. It is more serious than the ‘hide the decline’ situation because it gets to the heart of all of the paleo-hockeystick plots.  If you consider that they are saying any change in temps greater than 100 years in length are a complete unknown, how is it that we “know” that recent years are the warmest in history?  The very clear answer is – we don’t.

We might assume that the replies to this email were somewhat negative to a direct attack on all of paleo-thermometry but from these new emails we learned that in fact the reply by Keith Briffa was completely supportive #0435 #0643. I’ll leave the complete replies for others to locate if they want more information but the reply below from Keith Briffa should sum it up well.

ED
without the slightest doubt , I do wish to be involved in this AND/OR something like it –
what I wanted to do (to be frank) myself, is to do a piece with you, Tim and Tom Melvin and
Jan(?) , on the validity of the low frequency components of the family of reconstructions –
but with the emphasis on the tree-ring side . Tim is certainly (with me and you – remember)
doing a paper for The Holocene on the areas of uncertainty in these attempts (focusing on
calibration issues, spatial representation of predictors (spatial and time scale bias),
seasonal bias and relating these , ultimately. to the reliability of the reconstructions
{This is my version of what will be in it but he may disagree} . The basic point is that I
(and I think he) agree that Mike and Phil’s latest contribution is a step backwards ( in
time and understanding ) – well in reality I do not believe it is a step forward. I need to
read you message in detail and then phone tomorrow (I HAVE to get this PhD report off to
New Zeland now) after talking to Tim . You know I desperately want to produce a new
temperature reconstruction from the various tree-ring data (and explore the Mann western US
PC correction – though Malcolm has ignored my request for the data) . At the least , all
this requires that I come to see you (and perhaps Tim too).
I WILL be in touch ….
Keith

Just in case you are wondering whether Keith meant to agree with Ed Cook on the issue of long term variance, here is another email from Keith Briffa which restates the problem more clearly while indicating some of the pressures he is under for the IPCC report. Email #2009.

date: Thu Jan 20 10:04:49 2005
from: Keith Briffa
subject: Re: Re:
to: Edward Cook <drdendro@ldeo.columbia.edu>

Ed
will be discussing all this early next week with Gerrard. He is doing the US stuff at least
. We wish to do some longer (based on station records) stuff for some European locations
and try some reconstructions against oak data also.
I am trying to track down the NAO MSc thesis but it might be that the guy only looked at
post 1950 data – will let you know.
I am attaching the short 2000 year section from the ZOD of the IPCC report and the text of
a “box” on the MWP  (both confidential for now)
but if we can get more space , it needs expanding to cover SH and more hydro . They also
want an appendix on standardisation – so you will be involved in this also.
Really happy to get critical comment here . There is no doubt that this section will
attract all the
venom from the sceptics. I find myself in the strange position of being very skeptical of
   the quality of all present reconstructions, yet sounding like a pro greenhouse zealot here!
Told Peck that you (and Jan) will be CLAS
BEST WISHES
Keith

All present reconstructions!   It sounds to me that in private Keith and I could actually amicably discuss the issues over lunch.   In public though, it is another matter entirely. I’ve noted in the past that Dr. Briffa’s style in his published articles is to write clearly paper-disqualifying statements followed by astoundingly firm conclusions.  Now I’m understanding that this has to do with an internal battle between what he believes is true and the pressures of his job in publishing global warming papers. After all, just because we don’t really know historic temperature well, doesn’t necessarily mean we don’t know anything at all.  The big problem for paleoscience is that it might mean exactly – We don’t know! What’s more is that any closer examination of the math of the typical papers proves out the worst of the science.

“You need to pick cherries to make cherry pie”, D’Arrigo NAS panel investigation.

This sounds like an extreme remark but it is actually the standard in the field.  They actually have come to believe as a group that deleting data which doesn’t fit temperature and keeping data that does, results in a “true” temperature series.   The problem is that there are internal and external inconsistencies in what is an obviously insane approach. Non-scientific critics of this blog have often written, “Why would you keep data which doesn’t show correlation to temperature?”. This situation is a common problem in science where data is not good.  Normally you hypothesize that X is related to Y and then use stats to prove it does i.e. does cholesterol relate to heart disease. Imagine deleting the cholesterol data which didn’t agree!

In paleoclimate, the data is of such poor quality that the standard approach of using ALL of the data doesn’t work. At least it doesn’t show that there is a measurable response. Unfoutunately, what has happened in paleocliamte has been a decades long process of selecting particular series by hand and over time sorting the non-similar data such that you can average all the noise to get a reasonably temperature-looking curve in recent years. This sorting though is an unscientific nightmare caused somewhat inadvertently by the sheer mass of the government funded science.

The process I’ve described may sound too extreme to be true, but the “science” has has gone so far down this path that they have even expressed the unintended process mathematically using a very common paleo-algorithm called “composite plus scale” CPS. In CPS data is correlated to temperature and eliminated systematically such that the average of the remaining data shows a statistical correlation to temperature. I know it’s crazy sounding but there are more sophisticated algorithms as well. The problem is that all of them (100%) are forms of linear regression where individual series are weighted according to their ability to replicate measured temperature. Good looking data gets a strong weight, bad data is weakened.  Methods like RegEM, least squares, truncated least squares….on and on. Hundreds of papers processing the same data in generally the same way at enormous taxpayer cost.

Again you would be right to be skeptical of my claims. Let’s see what the scientists have to say about it #3622.

>At 06:20 AM 7/15/03 -0400, you wrote:
>>Hi Keith,
>>
>>Outdated as of June 28, 2003? Guilty as charged I guess. I’m not
>>familiar with this paper nor the authors. Of course I am skeptical.
>>In comparing my old fashioned least squares methods with advanced
>>’optimal’ methods like RegEM (that Mike is enamored with) and
>>hierarchical Bayes, there is fuck-all difference in the results.
>>Connie Woodhouse’s results with neural networks doesn’t show much
>>either over linear regression. If you are able to get a pdf, please
>>email it to me. I am not in position to get it now. Am at the beach.
>>
>>Cheers,
>>
>>Ed

There is also this extensive description of how data is selectively chosen.  It is a long email again but copied in full for context with relevent quotes bolded by me.

cc: Keith Briffa
date: Wed, 29 Mar 2006 14:36:50 +0100
from: Tim Osborn <t.osborn@uea.ac.uk>
subject: Re: Proxy time series
to: “Gustafson, Diane”

<x-flowed>
Dear Diane / Mike / NRC Committee,

At 22:18 28/03/2006, Gustafson, Diane wrote:
>Dear Tim:
>
>Our National Research Council Committee on Surface Temperature
>Reconstructions has been considering your paper with Keith Briffa
>published in a recent issue of Science.  Could you please elaborate
>on your criterion for selecting the proxy time series included in
>the analysis.  We are interested in how you computed the correlation
>between the proxy time series and local temperature time series.  Is
>the correlation based on filtered or detrended time series?  How
>would you counter the potential criticism that your selection method
>tends to favor proxy time series that show a strong 20th century warming?
>
>It would be most helpful for us if you could reply in time for us to
>consider your response at our meeting tomorrow morning.  Thanks in
>advance for your help.
>
>Mike Wallace

We (Tim Osborn and Keith Briffa) will first respond to these specific
questions about our recent Science paper.  In addition, copied below
are some further comments by Keith Briffa on issues related to
tree-ring proxy records, that may be of interest to the committee.

The primary purpose of our paper was to implement an alternative, and
possibly complementary, method of proxy-data analysis to the methods
used in most previously published reconstructions of past NH
temperature variations.  We did not want to introduce an entirely new
selection of proxy records (even if this were possible), because that
would obscure whether differences in our conclusions, compared with
published work, arose from our method or a different selection of
proxy records.

We decided, therefore, to make use of as many of the individual
records used in almost all the previously published NH temperature
reconstructions, excluding any records for which an indication of at
least partial temperature sensitivity was lacking.  So, very low
resolution records for which comparison with instrumental
temperatures is problematic were excluded.

We used records specifically from Mann and Jones (2003) and Esper et
al. (2002).  In addition we included records from Mann et al. (2003),
which I think just adds the van Engelen documentary record from the
Low Countries in Europe, because the others were already in the Mann
and Jones set.  We excluded duplicates, and our paper explains which
series we used where duplicates were present.  We did not average the
Tornetrask, Yamal and Taimyr tree-ring records as done by Mann and
Jones, because we could see no reason not to use them as individual series.

The series used by Mann and Jones had already been correlated with
their local instrumental temperatures — using decadally-smoothed,
non-detrended, values — so we accepted this as an indication of some
temperature sensitivity. For the other series, we calculated our own
correlations against local instrumental temperatures, trying both
annual-mean or summer-mean temperatures.  In our paper’s
supplementary information, we state that we used the HadCRUT2
temperatures for this purpose, which combines land air temperatures
with SST observations.  In fact, we used the CRUTEM2 land-only
temperature data set for this purpose.  These should be identical
where the proxy locations are not coastal.  For these correlations,
we did not filter the data, nor did we detrend it, and we used the
*full* period of overlap between the proxy record and the available
instrumental record.

We excluded records that did not show a *positive* correlation with
their local temperatures.  The remaining set includes most of the
long, high resolution records used by others, such as Moberg et al.,
Crowley and Lowery, Hegerl et al., Mann, Bradley and Hughes, etc. as
well as by Mann and Jones and Esper et al.

The final question, regarding the selection method favouring records
that show a strong 20th century warming trend, is a more
philosophical issue.  As stated above, we did not actually use
strongly selective criteria, preferring to use those records that
others had previously used and only eliminating those that were
clearly lacking in temperature sensitivity.  To some extent,
therefore, the question is then directed towards the studies whose
selection of data we used.  Certainly we did not look through a whole
host of possibilities and just pick those with a strong upward trend
in the last century! And we don’t think the scientists whose work we
selected from would have done this either.  There are very few series
to choose from that are >500 years long and are from proxy
types/locations where temperature sensitivity might be expected.  It
would be entirely the wrong impression to think that there are 140
such a priori suitable possible series, and that we picked (either
explicitly or implicitly) just those 10% that happened by chance to
exhibit upward 20th century trends.

The correlation with local temperature is an entirely appropriate
factor to consider when selecting data; these could be computed using
detrended data, though for those that we calculated, our use of
unfiltered data means that the trend is unlikely to dominate the
correlation.  One would need to inspect the trend in the temperature
data at each location to evaluate how much influence it would have on
the results; but in locations where a strong upward trend is present,
it would be right to exclude proxy records that did not reproduce it,
though also correct that a proxy shouldn’t be included solely on the
basis of it having the trend, especially where the proxy resolution
is sufficient to test its ability to capture shorter term fluctuations.

Finally, note that our method has not selected only those records
with a strong 20th century warming trend.  Of the 14 proxies selected
(see our figure 1), 7(!) do not have strong upward 20th century
trends: Quebec, Chesapeake Bay, W Greenland, Tirol, Tornetrask,
Mangazeja, and Taimyr.  Our method gives equal weight to all records,
so it should not be biased towards a single record, or a small number
of records, that do show strong upward trends.

Here are the additional comments on tree-ring issues:

I would also like to take the opportunity, if you will allow, to
comment briefly on some reports that have reached me concerning the
contribution made by Rosanne D’Arrigo to your Committee. Apparently,
this is being interpreted by some as reflecting adversely on the
validity of numerous temperature reconstructions that involve
significant dependence on tree-ring data. This is related to
Rosanne’s focus in her presentation on the apparent difference
between measured temperatures and tree growth in recent decades  – a
so-called “divergence” problem.
First let me make it clear that as I did not attend the Committee
meeting I am not able to comment specifically on the details of
Rosanne D’Arrigo’s actual presentation, though I am aware of her
papers with various co-authors related to this “divergence” in the
recent (circa post 1970 ) trends in tree-growth and temperature
changes as recorded in instrumental data, at near tree-line sites in
the Canadian Arctic. There are also other papers dealing with
‘changing growth responses’ to climate in North American trees.

I have co-authored a paper in Nature on the reduced response to
warming as seen in tree-ring densitometric data at high-latitude
sites around the Northern Hemisphere, increasingly apparent in the
last 30 years or so.

First, it is important to note that the phenomena is complicated
because it is not clearly identifiable as a ubiquitous problem.
Rather it is a mix of possible regionally distinct indications, a
possible mix of phenomena that is almost certainly in part due to the
methodological aspects of the way tree-ring series are produced. This
applies to my own work, but also very likely to other work.

The implications at this stage for the ‘hockey stick’ and other
reconstructions are not great. That is because virtually all long
tree-ring reconstructions that contribute to the various
reconstructions, are NOT affected by this. Most show good coherence
with temperature at local levels in recent decades. This is not true
for one series (based on the density data). As these are our data, I
am able to say that initial unpublished work will show that the
“problem” can be mitigated with the use of new, and again
unpublished, chronology construction methods.

In the case of the work by Rosanne and colleagues, I offer my
educated opinion that the phenomenon they describe is likely also, at
least in part, a chronology construction issue. I am not saying that
this is a full explanation, and certainly there is the possibility of
increased moisture stress on these trees, but at present the issue is
still being defined and explored. As the issue needs more work, this
is only an opinion, and until there is peer-reviewed and published
evidence as to the degree of methodological uncertainty , it is not
appropriate to criticize this or other work . For my part, I have
been very busy, lately with teaching and IPCC commitments, but we
will do some work on this now, though again lack of funds to support
a research assistant do not help.

The matter is important but I do not believe that the facts yet
support Rosanne’s contention, in her Global Biogeochemical Cycles
paper (Vol. 18, GB3021, doi:10.1029/2004GB002249, 2004) that an
optimum physiological threshold has been consistently exceeded at a
site in the Yukon. This conclusion should certainly not be taken as
indicating a widespread threshold exceedence.

It was my call not to “overplay” the importance of the divergence
issue, knowing the subtlety of the issues, in the fortcoming IPCC
Chapter 6 draft. We did always intend to have a brief section about
the assumption of uniformitarianism in proxy interpretation ,
including mention of the possible direct carbon dioxide fertilization
effect on tree growth (equally controversial), but it is likely to
conclude that here as well , there is no strong evidence of any major
real-world effect. This and the divergence problem are not well
defined, sufficiently studied,  or quantified to be worthy of too
much concern at this point. The uncertainty estimates we calibrate
when interpreting many tree-ring series will likely incorporate the
possibility of some bias in our estimates of past warmth, but these
are wide anyway. This does not mean that temperatures were
necessarily at the upper extreme of the reconstruction uncertainty
range 1000 years ago, any more than they may have been at the bottom.
The real problem is a lack of widespread (and non-terrestrial)
proxies for defining the level of early warmth, and the vital need to
up-date and study the responses of proxies in very recent times.

Best regards,

Tim Osborn and Keith Briffa

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

Ok, so we can see that there is absolutely no question that data have been preferentially selected for correlation to temperature.  I’m sure that we all agree — If you chose data which fits your conclusion, it is certain that you will find what you seek.  What is amazing is that the science has self-sorted its people into those who believe in this kind of nonsense.

On deletion of data:

Tim Osborne writes this partial email in #2346

We’re now using the MXD data set with their program and the Jones et al. data
to see: (i) if the missing data from 1856-1960 in the Jones et al. data set
can be filled in better using the MXD plus the non-missing temperatures
compared to what can be achieved using just the non-missing temperatures.  I
expect that the MXD must add useful information (esp. pre-1900), but I’m not
sure how to verify it!  The program provides diagnostics estimating the
accuracy of infilled values, but it’s always nice to test with independent
data.  So we’re doing a separate run with all pre-1900 temperatures set to
missing and relying on MXD to infill it on its own – can then verify, but need
to watch out for the possibly artificial summer warmth early on.  We will then
use the MXD to estimate temperatures back to 1600 (not sure that their method
will work before 1600 due to too few data, which prevents the iterative method
from converging), and I will then compare with our simpler maps of summer
temperature.  Mike wants winter (Oct-Mar) and annual reconstructions to be
tried too.  Also, we set all post-1960 values to missing in the MXD data set
(due to decline), and the method will infill these, estimating them from the
real temperatures – another way of “correcting” for the decline, though may be
not defensible!

First, this email makes the corruption of “hide the decline” fame is absolutely crystal clear.  It cannot be denied despite the investigations into climategate 1.0 by the august panels. Even Michael Mann vehemently disagreed with this sort of hack-stat approach.  From Real Climate:

Whatever the reason for the divergence, it would seem to suggest that the practice of grafting the thermometer record onto a proxy temperature record – as I believe was done in the case of the ‘hockey stick’ – is dubious to say the least.

[Response: No researchers in this field have ever, to our knowledge, “grafted the thermometer record onto” any reconstruction. It is somewhat disappointing to find this specious claim (which we usually find originating from industry-funded climate disinformation websites) appearing in this forum. – from Mann

In case you were wondering, everyone who disagrees with Mike is fossil industry funded.  I keep waiting for my check. You might not think that this sort of falsification would be possible in peer reviewed literature but would you be surprised to find out that this actually happened?  Email #4022:

cc: p.jones@uea.ac.uk
date: Wed Jul 20 16:58:40 2005
from: Tim Osborn <t.osborn@uea.ac.uk>
subject: Re: crowley
to: Keith Briffa, Tom Wigley

Hi Tom,
as a followup to Keith’s email, it might be quite likely that one of the series you plot is
replaced by the instrumental record after 1960, because the file from Crowley and Lowery
that is available at the WDC-Paleoclimate contains such a record.  The header states:
—————————————-
Crowley and Lowery 2000 (Ambio 29, 51)
Northern Hemisphere Temperature Reconstruction
Modified as published in Crowley 2000
(Science v289 p.270, 14 July 2000)
Data from Fig. 1, Crowley 2000:
   Decadally smoothed time series of Crowley-Lowery reconstruction
   spliced into smoothed Jones et al instrumental record after 1860
   (labeled CL2.Jns11), and a slight modification (labeled CL2)
   of the original Crowley and Lowery reconstruction to 1965.
—————————————-
The URL of this file is:
[1]ftp://ftp.ncdc.noaa.gov/pub/data/paleo/gcmoutput/crowley2000/crowley_lowery2000_nht.txt
and it is listed here:
[2]http://www.ncdc.noaa.gov/paleo/recons.html
Cheers
Tim
At 12:22 18/07/2005, Keith Briffa wrote:

as a first quick response – the Crowley numbers came from his paper with Lowery. I seem
to remember that there were 2 versions of the composite that he produced – certainly we
used the data that did not include Sargasso and Michigan site data. I presume the other
(from the CRU web site) were the data used by Phil and Mike Mann that they got from him
(where exactly did you pick then up from?)and could be the other data set (with those
sites included). It seems odd that the values are so high in the recent period of this
series and could conceivably be instrumental data , but would have to check. The scaling
of the data we used to produce the Crowley curve that formed one of the lines in our
spaghetti diagram (that we put on the web site under my name and made available to
NGDC), was based on taking the unscaled composite he sent and re-calibrating against
April – Sept. average for land North of 20 degrees Lat., and repeating his somewhat
bazaar calibration procedure (which deliberately omitted the data between 1900-1920 that
did not fit with the instrumental data (remember his data are also decadal smoothed
values). In fact , as we were using summer data we calibrated over 1881-1900 (avoiding
the high early decades that I still believe are biased in summer)  and 1920 – 1960 ,
whereas he used 1856-1880 and 1920-1965.  Of the precise details might differ – but the
crux of the matter is that I suspect one of the Figures you show may have instrumental
data in the recent period – but not ours. If you say exactly where these series came
from I can ask Tim (who will have done the calibrations) to check.
As  for the second question , the QR data are averaged ring widths from relatively few
site chronologies in the high north (mostly N.Eurasia – Scandinavia,Yamal,Taimyr),
though with a few other site data added in as stated. The 2001 data are the MXD data
from near 400 sites and provide the best interannual to multidecadal indication of
summer temps for land areas north of 20 degrees than any of the true proxy (ie not
including instrumental ) data. No idea what the correlation over the common 600 year
period is – but I have never said that the ring width is anything other than summer
temps for the area it covers .
Keith
At 20:38 15/07/2005, you wrote:

Keith,
Look at the attached. Can you explain to me why these plots
differ — particularly after 1880?
Could you also explain why the Briffa data in QR 2000 are so poorly
correlated with the Briffa 2001 data?
I think I know the answers, but I want an independent and spontaneous
answer from you.
Thanks,
Tom.

—
Professor Keith Briffa,
Climatic Research Unit
University of East Anglia
Norwich, NR4 7TJ, U.K.
Phone: +44-1603-593909
Fax: +44-1603-507784
[3]http://www.cru.uea.ac.uk/cru/people/briffa/

Tim Osborn took this approach in #4005:

the gridding and calibration were done.  Also we have applied a
completely artificial adjustment to the data after 1960, so they look
closer to observed temperatures than the tree-ring data actually were
— don’t rely on the match after 1960 to tell you how skilfull they
really are!

Conclusion:

Climategate 2 is more interesting than climategate 1 for several reasons.  We’ve seen the infilling of several conversational lines in the original emails, numerous references to funding, corruption and information control, there is additonal reason to believe the IPCC was corrupted by political aims and the thought processes in paleoclimate are more clear.    It will take months to sort the whole thing out but in the meantime, we can understand that the core of thermometer paloclimatology is as rotten as any tree in the forest.

Readers shouldn’t imagine that the reasons for my statements are based solely on these emails. First, I’ve been at this for several years now reading papers, doing math and writing posts.  What’s more, there are so many additional emails to support my statements they would exceed anything we could reasonably put in a blog post. If you don’t think I’ve made the case, ask questions, read the emails and learn for yourself.   The whole mess is in the open now, it is up to you whether the true state of climate change science is worth understanding.

Jeff Condon – Id