the Air Vent

Because the world needs another opinion

Context

Posted by Jeff Id on November 28, 2009

John Pittman asked to post this here. It’s probably the longest blog post I’ve ever read but it provides some context for Yamal and the original hockey stick with emails in the appropriate timeframe. It has a couple of amazing quotes and it should provide the more studious reader with some good information.

Guest post – John Pittman

Historical Perspective of Why Yamal Matters

I can say conclusively that the hacked emails are just blips of information that will have absolutely no impact whatsoever on the push to get policymakers to back the science,” said Anne Kelly, the policy director at Ceres, a sustainable business network whose members include PepsiCo, American Airlines and Bloomberg. Already the damage control is starting. The Monbiot is a classic. http://www.monbiot.com/archives/2009/11/23/the-knights-carbonic/ “”But do these revelations justify the sceptics’ claims that this is “the final nail in the coffin” of global warming theory?(8,9) Not at all. They damage the credibility of three or four scientists. They raise questions about the integrity of one or perhaps two out of several hundred lines of evidence. To bury manmade climate change, a far wider conspiracy would have to be revealed””.

This poor thinking and straw man/red herring mix needs to be challenged each time it is repeated. The first is just nonsense. I have spent three days and still have 80 more pages to read and study, after this long post, and this is just a partial list per the posters. Since this was a partial list per the posters, and no one has had time to analyze the impact, using an absolute term (absolutely no) that it will have no impact after a few short days, means that it is not about science at all. Though that statement of no impact may end up being true, it means that they have concluded the science doesn’t matter, because these blips of information show that the deck was stacked, and impartial science was evaded, purposedly. If the statement by Kelly is true, each person should contact their representatives and complain about being misled that this was about science and not greed, by PepsiCo and others, in pursuit of tax dollars, or cap and trade dollars.

The Monbiot is a classic due to the misleading by using facts to ignore the argument. The first point is that the basic global warming theory is based on sound physics. Little argument on basic facts. It is the magnitude that is important. Second, it ignores the historical development of the IPCC’s work, which we will examine below. The credibility damage of three or four scientists is also misleading. These are not just any scientists. No, these are the ones for whom it will be shown they took the AGW meme from “influencing global climate” to “global climate change is the greatest threat facing mankind.” Expect others to soon follow trying to downplay what occurred. This development, from just an influence to a catastrophe, will be detailed, and it will show that there will probably be a long line of misleading apologists in the near future. Next are a straw man and a red herring. It started with global warming theory and it highlights “one or perhaps two out of several hundred lines of evidence”. The hundreds of lines of evidence concern warming, not AGW. In paper after paper measuring the change, AGW is cited as the cause. But the papers have nothing to do with proving AGW, they only document the changes. Yes, it has been getting warmer since the Little Ice Age. Typical “bait and switch”. Few are arguing about all the lines of evidence showing that is getting warmer. The real argument concerns present temperature, past temperature, climate sensitivity and climate predictions (projections). To understand what the furor is about one has to go back to the SAR.

The story starts with the first CRU FOI text file Alleged CRU Email – 857677215.txt. Selected quotes below. I have cut out repetitive email, etc. I have also reformatted some for space requirements. This has the possibility of introducing small errors. I highly recommend that persons go to the originals that can be searched with “larch” and “sensitivity.”

The time is 1997. MBH has not been published and the IPCC has published the second assessment (SAR). The first email shows that the SAR has unresolved issues dealing with past climate resolution. It is a proposal. Issues that should be familiar with all critics of the post MBH98 IPCC work. At the time of the SAR, Lamb’s Central England temperatures have the longest, most detailed, and best resolution for millennial scale reconstructions. It has a problem. It conclusively shows a warmer medieval warm period than the current period. In the first text, familiar concerns about forcings and strong climatic signals come into play. The SAR has a fatal problem for the alarmists of the IPCC. It cannot support the AGW call to arms. It basically has to say, we believe that the current warm period is influenced by man (it does not support being alarmed). The TAR WG1 in commenting on the SAR had this to say “the report concluded that the ability to quantify the human influence on global climate was limited.” Not exactly a war cry that can be expected to unite a world addicted to cheap carbon based energy. This is the SAR Chapter 8 Summary p 412 “these results indicate that the observed trend in global mean temperature over the past 100 years is unlikely to be entirely natural in origin. More importantly, there is evidence of an emerging pattern of climate response to forcings by greenhouse gases and sulphate aerosols in the observed climate record. Taken together, these results point towards a human influence on global climate.” The quotes below indicate why Yamal and Taimyr were considerd important and what was thought would be learned from the research.

From: Eugene Vaganov evag@xxxxxxxxx.xxx

To: k.briffa@xxxxxxxxx.xxx

Subject: from Vaganov

Date: Thu, 6 Mar 97 14:40:15 +0000 (KRS)

The specific objectives of this proposal are the development of two supra-long (each spanning 6-9000 years up to present) continuous larch ring-width chronologies at two distant each other high-latitude locations of Siberia (Yamal and Taimyr peninsulas). Ring-width chronologies developed from coniferous trees growing at the polar timberline in Siberia contain a very strong climatic signal, mainly summer air temperatures. With these chronologies high-resolution continuous and quantitative reconstruction of summer temperatures will be made.

3.2 OBJECTIVES This research will make a major contribution to our knoweledge of high-resolution climate variability at high latitudes of Western and Middle Siberia throughout the Holocene using the unique potential of tree-ring data. The specific objectives of this proposal are as follows:

- to develop two supra-long (each spanning 6-9000 years up to present) continuous ring-width larch chronologies at two high-latitude locations of Siberia; – using these tree-ring chronologies, to make a multi-millennial high-resolution continuous and quantitative reconstruction of summer temperatures;

- to analyse spatio-temporal patterns of temperature variability at these locations over a range of timescales (annual, decadal, multi-decadal and centennial) and their connections with various forcing factors and other annual resolution records being developed elsewhere in the Arctic and Subarctic.

3.3. BACKGROUND Reconstruction and analysis of natural climatic changes through the whole Holocene at high latitudes are of great importance as climatic conditions, especially air temperature, are most variable and sensitive to various forcing functions (Budyko, 1980; Jones and Kelly, 1983; Intergovernmental Panel on Climate Change, 1990). However, there are a minute quantity of long, precisely-dated and high-resolution proxy climatic series for these regions.

Tree rings as a proxy indicator of the past climatic conditions are of special interest as they allow to reconstruct climatic parameters with seasonal and annual resolution for many hundred and thousand years, to provide an exact absolute and relative dating of the tree-ring data, to establish high-frequency climate changes (from interannual to centennial timescales) with high confidence, to obtain dendroclimatic information practically for every site where trees grow at present or grew in the past.

Ring-width chronologies developed from coniferous trees growing at the polar timberline in moderate-continental and continental regions of Siberia contain a very strong climatic signal, mainly summer air temperatures of tree growth year (Graybill and Shiyatov, 1992; Briffa, Jones, Schweingruber, Shiyatov and Cook, 1995; Hantemirov, 1995; Vaganov, Shiyatov and Mazepa, 1996). The explained variance over the calibration and verification periods is highest reported in the literature to date (65-70%) and it allows to make a quantitative reconstructions of summer temperatures. These chronologies and temperature reconstructions will be the first to be so long, reliable, annually-resolved and precisely-dated with known reliability across the whole of northern Hemisphere. These reconstructions will allow to compare and contrast the details of temperature changes at the moderate-continental region of Yamal Peninsula with the continental region of Taimyr Peninsula and allow modern and predicted temperature patterns to be compared with variability patterns of pre-industrial era.

- The Climatic Research Unit of the University of East Anglia, Norwich, Great Britain is one of the world’s leading research organisation specialising in the study of climate change: climate history, current climates, projected changes and impacts. Dr. K.R.Briffa, Senior Research Associate at the Climatic Research Unit, has considerable experience in climatology and with the use of statistical methods of climate analyses and dendroclimatic reconstruction, especially with regard to large-spatial-scale reconstructions of climate patterns and published many articles on the theoretical and practical aspects of dendrochronology and dendroclimatology, and on use of paleoclimate data for understanding current and possible future climates.

Dr K.R.Briffa (Climatic Research Unit) will be the responsible scientist on the proposed project and he will take part in analysing growth-climate relationships, developing statistical models of tree growth, extracting climatic signal, reconstructing and analysing climatic conditions of the remote past.

The Russian laboratories together with the Climatic Research Unit of the University of East Anglia during 1997-1999 will be analysing the material obtained (standardization of individual series, development of mean chronologies, studying growth-climate relationships, developing statistical models of tree growth, extracting climatic signal, reconstructing and analysing climatic conditions of the remote past). This work will be finished at the end of 1999.

Along comes MBH98, and the MWP has disappeared. Better than that, the large variance of temperatures which would preclude getting excited even if warming was being caused by manmade greenhouse gases, have disappeared as well. The IPCC was so impressed, the paleo-graphs exploded across the third report (TAR). The furor climaxes with Mann being declared Time’s Man of the Year. Now the IPCC has a war cry. Temperatures have not been this hot for ten thousand years or more. It has to be manmade, and we must do something. It will be important to remember this chronology when the effects of recent revelations are discussed. It will be important to remember this is about the shaft, not the blade of the hockey stick. It will be important to remember that even back in 1997 that dendrochronology and dendroclimatology, use paleoclimate data for understanding current and possible future climates.

With the TAR, the UN realizes that they finally have a shot at getting something they always wanted. The legitimacy to tax, and disperse monies. For decades the UN had been thwarted by such countries as the United States that refused to give self funding authority to the UN. They refuse to give up their veto powers. Now comes a long an issue so large it cannot be ignored and selfish, sovereignty issues cannot be allowed to derail the salvation of the world. With the different systems, monies, etc, there has to be a brokerage for all the monies, regulations, and the day to day accounting that would be entailed to change the way humans obtain the largest fraction of energy used for civilization. And a model is proposed. The cap and trade that had worked for acid rain would provide a market mechanism that could be traded, accounted, and most basically, monies could be kept as a service charge. For governments it provided a way to access huge monies, take a small, basically hidden tax, and be justified on the basis of saving the world. However, the cap and trade has a problem. The acid rain (SO2) cap and trade worked because there were cheap alternatives. For a small increase in equipment costs, acid could be scrubbed. For a small increase in costs, cleaner fuel could be used. Something came along that took attention away from the fact that the SO2 model was inappropriate for GHG’s. The miserable record from the Kyoto Agreement proves that cap and trade, with offsets, works little, if at all, and more importantly, does cost a lot. That something was Al Gore’s “An Inconvenient Truth.” So begins the PR blitz that changes the policy scene to a media fest.

But there is a problem. After getting an argument that could be used to bring reluctant nations such as the United States, two researchers release a paper that destroys the poster boy “Hockey Stick.” Up to and beyond the 4AR, the self-named “Team” fights to save the Hockey stick. Even worse, their efforts expand to include the Briffa Yamal use. The Wegman and North reports demolish the use of certain chronologies and methodology of MBH98. Further negative developments include a court decision that the PR side, “An Inconvenient Truth” is propaganda. The basis for immediate and wide ranging action, and its most visible PR tool, is being derailed. At this point, I think an editorial comment is appropriate. After reading the selected emails that I used for this post, it appears that the Process is at fault and not Dr. Briffa. His recent statement of working on these dendro problems is reflected in the emails. He never stopped working on the science. Later when we start exploring just how important the MWP is, we find the pursuit of consensus ran rough shod over the science; and since Dr. Briffa was doing science, he and his work were simply not put in the best light. IMO. It is also apparent that from the beginning, a castle mentality was enforced from Dr. Mann especially that exists to this day as far as can be told, and unfortunately it does affect the claim of impartial science.

But there is another chronology that shows the “hockey stick.” It is the Yamal series, and it is latched on to in order to justify a claim of independent support for the hockey stick. It starts showing up in study after study. Fast forward to right before the release of the emails. It has taken the place of the discredited series and papers based on MBH. But, the persons, and now even more professionals are dissecting the Yamal, and Taimyr, and finding problems. So we will look at the history of the “hockey stick” controversy from the Yamal perspective tying it in with the overall development of the TAR and 4AR. The next quote outlines the fertilization question that became an issue with the MBH Wegman and North papers.

>>On Mon, 3 Nov 1997, Keith Briffa wrote:

>> I have been agonising for months that these results are not some

>> statistical artifact of the analysis method but we can’t see how. For just

>> two species (spruce in the western U.S. Great Basin area and larch in

>> eastern Siberia) we can push the method far enough to get an indication of

>> much longer term growth changes ( from about 1400) and the results confirm

>> a late 20th century apparent fertilization! The method requires

>> standardizing (localized mean subtraction and standard deviation division)

>> by species/age band so we reconstruct relative (e.g. per cent change) only .

>> We have experimented with integrating the different signals in basal area

>> and density(after extracting intra ring ring width and density data where

>> available) within a ‘flat mass’ measure which shows a general late 20th

>> century increase – but whether this incorporates a defensible relative

>> waiting on the different components (and what the relative carbon

>> components are) is debatable. We now need to make some horrible simplistic

>> assumptions about absolute carbon in these (relatively small) components of

>> the total biomass carbon pool and imlpications for terrestrial and total

>> carbon fluxes over the last few hundred years – and beyond! Without these

>> implications we will have difficulty convincing Nature that this work is

>> mega important.

The next quote outlines some of the objections skeptics have had of the use of paleoclimatic data. The email to Briffa indicate that the tree line and most favorable conditions were 5000-1700BC, and there is no evidence of the polar timberline moving northward for the past century (about 1897). This does not support the claim that CWP is special in terms of most favorable conditions for tree growth.

From: Rashit Hantemirov rashit@xxxxxxxxx.xxx

To: Keith Briffa k.briffa@xxxxxxxxx.xxx

Subject: Short report on progress in Yamal work Date: Fri, 9 Oct 1998 19:17:12 +0500

Reply-to: Rashit Hantemirov rashit@xxxxxxxxx.xxx

Dear Keith, ………….

According to reconstructions most favorable conditions for tree growth have been marked during 5000-1700 BC. At that time position of tree line was far northward of recent one. [Unfortunately, region of our research don't include the whole area where trees grew during the Holocene. We can maintain that before 1700 BC tree line was northward of our research area. We have only 3 dated remnants of trees from Yuribey River sampled by our colleagues (70 km to the north from recent polar tree line) that grew during 4200-4016 and 3330-2986 BC.] …..During last 3600 years most of reconstructed indices have been varying not so very significant. Tree line has been shifting within 3-5 km near recent one. Low abundance of trees has been fixed during 1410-1250 BC and 500-350 BC. Relatively high number of trees has been noted during 750-1450 AD. There are no evidences of moving polar timberline to the north during last century.

The next quote supports the previous posts of Why Yamal Matters. In this email sensitivity, Bayesian criteria, and other items are discussed. By the time of the 4AR, this approach with millenial reconstructions are used to justify the claim that only with CO2 forcings can models replicate the CWP. But there will remain a problem that McIntyre, McKitrick, and others continue to explore to this day, and was shown in the Wegman report. The high resolution reconstructions needed for claiming very likely, and that most of the warming of the latter part of the 20th century are not truly independent. In a seemingly prescient way, Wegman outlines how the team is writing with each other, reviewing each others papers, and the recent email released show that they were gaming the system against those who were not in their group, according to what I will show below, releases in blogs, and in newspapers across the world. It casts a bad light on those involved. For the innocent, there is an old saying “One should not complain of fleas, when sleeping with dogs.”

From: Bryson Bates bryson@xxxxxxxxx.xxx

To: Barrie Pittock barrie.pittock@xxxxxxxxx.xxx

Subject: Re: uncertainties guidance paper

Date: Mon, 14 Dec 1998 18:58:01 +0800 (WST)

Cc: “‘econf.part2@xxxxxxxxx.xxx'”

econf.part2@xxxxxxxxx.xxx

> 6. Regarding para. 67, I am more concerned about the “best” or “central”

> estimate for climate sensitivity of 2.5 deg.C for 2xCO2 than about the

> range. Several lines of evidence (paleo-evidence, fitting models to the

> last 100 years, the distribution of improved model results) all suggest

> that the “best estimate” for this increasingly dated and artificial

> notion should be raised from 2.5 to nearer 3.5. This would be

> controversial, but I believe it would also be giving the best advice

> possible. Whatever you believe is the correct number, the level of

> concern such a change would raise is in itself evidence for the

>importance of central estimates in the climate change debate.
This could be investigated and quantified in a Bayesian framework.

> 7. I share Martin Manning’s problems with the use of the term “Bayesian”

> and equating it with “subjective”. Personally I think this paper should

> avoid such specialist technical terms if possible, especially if there

> is disagreement about what they mean!

Yes: Bayesian methods provide a means of combining prior (expert) knowledge with data to quantify the posterior distribution. The prior knowledge may be based on the results of previous experiments and need not be subjective. Another point is that formal application of Bayesian methods usually leads to problems that are analytically intractable. The recent development of Markov chain Monte Carlo methods has largely overcome this.

The next one is one of those unbelievable ones that needs to be included to understand some of the apologists comments. In 1999, they did not work on the assumption that the scenarios were realistic. More importantly, they did not, or at least Dave did not have full confidence in climate system model projections of confidence. The important part for this post is the appraising of problems, certainties, etc. were considered. This will preclude apologists (or should) trying to claim later that somehow the effects of models, paleo reconstructions, and their effects somehow were not considered when we start dissecting the effect of MBH and Yamal.

From: Dave Schimel schimel@xxxxxxxxx.xxx

To: Shrikant Jagtap sjagtap@xxxxxxxxx.xxx Subject: RE: CO2

Date: Mon, 17 May 1999 09:21:35 -0600 (MDT)

Cc: franci <franci@xxxxxxxxx.xxx>, Benjamin Felzer <felzer@xxxxxxxxx.xxx>, Mike Hulme <m.hulme@xxxxxxxxx.xxx>, schimel@xxxxxxxxx.xxx, wigley@xxxxxxxxx.xxx, kittel@xxxxxxxxx.xxx, nanr@xxxxxxxxx.xxx, Mike MacCracke mmaccrac@xxxxxxxxx.xxx

I want to make one thing really clear. We ARE NOT supposed to be working with the assumption that these scenarios are realistic. They are scenarios-internally consistent (or so we thought) what-if storylines. You are in fact out of line to assume that these are in some sense realistic-this is in direct contradiction to the guidance on scenarios provided by the synthesis team.

If you want to do ‘realistic CO2 effects studies, you must do sensitivity analyses bracketing possible trajectories. We do not and cannot and must not prejudge what realistic CO2 trajectories are, as they are ultimatley a political decision (except in the sense that reserves and resources provide an upper bound).
‘Advice’ will be based on a mix of different approaches that must reflect the fact that we do not have high coinfidence in GHG projections nor full confidence in climate system model projections of consequences.
Dave

The next email is posted to show that if these are not authentic, it should be easy to prove. In this discussion, problems are outlined; and I love the response, pick a value. Kinda like pic-a-flic climate sensitivity. But this is apparently one of those expert conversations that would require a lot of expertise to say that the response was inappropriate. Just what one would expect in emails among professionals with a difficult subject.

From: David Viner d.viner@xxxxxxxxx.xxx

To: m.hulme@xxxxxxxxx.xxx, s.raper@xxxxxxxxx.xxx

Subject: Fwd: Re: Climate Sensitivity

Date: Tue, 18 May 1999 11:48:40 +0100
Mike

The climate sensitivity of HadCM2…..pick a value between 2.5 and 4.1K

D

>Envelope-to: f046@xxxxxxxxx.xxx

>Date: Tue, 18 May 1999 11:27:48 +0100 (BST)

>From: T Johns tcjohns@xxxxxxxxx.xxx

>Subject: Re: Climate Sensitivity

>To: d.viner@xxxxxxxxx.xxx

>Cc: tcjohns@xxxxxxxxx.xxx

>Status:

>

>Hi David,

>

>I have just got back from leave today – sorry for the lack of response

>to your emails.

>

>On climate sensitivity, the equilibrium sensitivity in HadCM2 was difficult

>to get a definitive answer for initially as the conventional slab experiment

>was unstable, so we estimated it from part of a transient coupled run

>instead. We quoted 2.5 K in the original Nature paper. Recently we

>have done a HadAM2 slab experiment (modified sea ice and slab ocean physics)

>which indicated 4.1 K rather than 2.5 as an equilibrium value. This is

>quoted in a paper submitted as a CMIP study. The HadAM3 conventional

>slab experiment gave the 3.3 K figure I think. The HadCM2 discrepancy

>indicates the perils of this yardstick; other research here suggests that

>the effective climate sensitivity does respond to climate change feedbacks

>in transient experiments (with HadCM2 particularly). The early 2.5 K

>estimate has been revised upwards based on a long coupled run of HadCM2 to

>be closer to the 3.3 K we got from HadCM3 equilibrium slab experiments.

>

>Comparing transient temperature responses to similar time-varying forcing

>may be a better indication of real sensitivity, but so long as we quote

>single climate sensitivity numbers I fear that there is scope for confusion.

>

>Tim.

>

Now that we have established that the emails appear to be real, and that the work supports the development of combining reconstructions for model sensitivity as was written in TAR and 4AR, we go to the heart of the issue. The next email is in 2001. In it is the discussion of the claim that the MWP is not as warm as the CWP. T.L. Delworth has some insightful questions. In order to understand that the MBH98 did not immediately turn the SAR and proxies over, this is a mustread. It also shows that the proxy reconstructions and models go hand in hand. This is a point the apologists will want to ignore. I have included just the parts that support that ongoing discussions of models and contentions about the MWP wrt CWP were occurring. Obviously, a draft of a letter to be published may be historically interesting, but the final letter should be the one read, and considered. It would be inappropriate to argue its (draft) merits.

From: “Thomas L. Delworth” td@xxxxxxxxx.xxx

To: “Michael E. Mann” mann@xxxxxxxxx.xxx

Subject: Re: letter to Science

Date: Thu, 01 Mar 2001 08:19:45 -0500

Cc: tom@xxxxxxxxx.xxx, hpollack@xxxxxxxxx.xxx, mhughes@xxxxxxxxx.xxx, rbradley@xxxxxxxxx.xxx, p.jones@xxxxxxxxx.xxx, k.briffa@xxxxxxxxx.xxx
Dear Mike et al,

I offer the following comments on your letter for your consideration.

It seems to me there are 2 primary issues to address: (A) what does proxy evidence say about whether the Medieval Warm period was global (B) what do we know about potential mechanisms for the Medieval Warm period (i) evidence for a forced phenomenon (ii) evidence for internal variability. Issue (A) is currently dealt with in your sections (1) and (2). One point that could be perhaps conveyed more clearly is the necessity of using the spatial information conveyed in (multi) proxy reconstructions, rather than overly interpreting sets of local proxy evidence. I felt this point could have been stressed more, and is one which the casual reader may not appreciate. Issue (B, Bi) is in your section (3). I suggest a more explicit mention of conclusions with regard to the Medieval Warm period in recent work on this topic. The first statement in this section doesn’t provide (I don’t think) explicit evidence to back itself up. The sentence starting “These results …” could be more explicit about what those studies show with respect to the Medieval Warm period, in addition to the more general statement about the partitioning between forced and internal variability. A reader could ask “Ok, if 50% of the variability is explained by volcanic and solar forcing, that doesn’t exclude the other 50% playing a strong role for events such as the Medieval Warming.” Such a question could be dealt with in advance by stating what role these studies suggest for radiative forcing in the Medieval Warm period.

………………………..

(1) I agree with the overall message you are conveying, but might choose somewhat differing wording in a place or two. The statement is made “(1) It cannot reasonably be argued that the Middle Ages were as warm as the 20th century at global or hemispheric scales.” This might be a bit strong … I would think one can have a reasoned discussion on this topic. Perhaps something like “We strongly disagree with the assertion that the Middle Ages were as warm as the 20th century at global or hemispheric scales.”

……………………………………..
Regards,
Tom Delworth

…………………………………….

pps I previously provided to Tom correlations between the THC and global/hemispheric temperature based on a 900 year run of our R30 coupled model. These correlations were relatively low (0.27), but probably significant. The applicability of those correlations to the issue of the Medieval Warming may not be strong. If the Medieval Warming is a multi-century event, then I should really be looking at the correlations of low frequency (>50 years) filtered model output from a run of several millenia duration. Thus, the 900 year run may not be applicable. I will revisit this topic using a multi-millenial R15 coupled run, but probably won’t have any results today. I don’t think that would change the essential conclusions, however. I recall that experiments with the R15 model in which the THC was substantially weakened through the addition of fresh water to the North Atlantic provided strong regional temperature anomalies, but their global expression was small. These experiments are being repeated with the higher resolution model. In light of these issues, I suggest that the focus be not so much on saying the THC cannot be responsible for the Medieval Warming, but rather on saying (1) there is strong evidence for a substantial role of radiative forcing, and (2) the burden is on the author to provide evidence for the role of the THC.

?

“Michael E. Mann” wrote:

> Dear Colleagues,

>

> Below is a draft of a short letter to Science that Tom Crowley and I

> have put together, after discussing w/ Phil, Ray, and Malcolm. We

> feel that a reply to Broecker’s recent “Perspectives” piece is

> warranted to correct several misconceptions that Wally unfortunately

> chose to perpetuate

………………………………

> Thanks in advance for your feedback,

>

> mike

>
> _________________________________________
>
> Medieval Warming Redux

In a recent “Perspectives” opinion piece, W. Broecker suggests that the “hockey stick” reconstruction of climate change over the past 1000 years – with extreme warming only in the late 20th century – is incorrect, and that the so-called “Medieval Warm Period” was at least as warm as the 20th century and due to oscillations in the thermohaline circulation. To reach this conclusion, Dr. Broecker rejects traditional empirical “proxy” climate indicators of past climate (e.g. tree ring, ice core, coral, and long historical documentary records) that are the foundation of a number of hemispheric reconstructions, as well as our current best physical understanding of the factors controlling climate at century-to-millennial timescales. We disagree with Broecker on several major points: (1) It cannot reasonably be argued that the Middle Ages were as warm as the 20th century at global or hemispheric scales. Although regional warmth during the Middle Ages may have sometimes been significantly greater than present, four different hemispheric-scale reconstructions (Jones, Mann, Briffa, Crowley) have been completed for the last 1000 years — all of them showing warmth in the Middle Ages that is either no warmer or significantly less than mid-20th century warmth. This is because it has been known for a quarter of a century that the timing of warmth during the Middle Ages was significantly different in different regions (Lamb, Dansgaard, Hughes). Failure to take this observation into account can lead to serious errors in the inference of hemispheric temperature trends

…………………………………………….

Our conclusion is also supported by measurements from tropical glaciers indicating an unprecedented level of recent warming with respect to the last 1,000-2,000 years (Thompson). (2) High-resolution proxy climate records which form the foundation of recent hemispheric temperature reconstructions are far more reliable indicators of century-to-millennial scale climate variability than is implied by Broecker. The potential limitations in interpreting long-term climate change from proxy indicators such as tree rings, have been long recognized by dendroclimatologists (e.g., Cook “segment curse” paper) and are almost always taken into account in framing interpretations of long-term trends. For example, Mann et al (1999) verified that a significant subset of multiple-millennial length tree ring and ice core proxy climate indicators used to reconstruct the trend over the past millennium passed rigorous statistical tests for fidelity at the millennial timescale, and that the basic attributes of the hemispheric reconstruction using more recent non-tree ring proxies available over the past few centuries yielded essentially the same result as that based on both tree ring and non-tree ring based information (Mann et al, Earth Interactions, 2000). Several independent reconstructions (Jones et al and Crowley and Lowery ), using a wide variety of proxy climate indicators and different statistical approaches, yield similar hemispheric temperature trends. Even the centennial-scale changes within the so-called “Little Ice Age” of the 15th-19th centuries are largely in agreement. Furthermore these centennial changes have been shown to be in “agreement”, rather than “in opposition” (as argued by Broecker) with evidence from alpine glacial advances

……………………………………………………..
(4) It is not justifiable to argue that changes in the thermohaline circulation cause significant hemispheric or global changes in temperature. Although changes in the conveyor play a major role in the Atlantic Basin, to a first approximation changes in ocean circulation simply redistribute heat on the planet without significantly raising global temperature, or even hemispheric temperature. This conclusion is born out by very low correlations between warmth in the Greenland sector and the hemispheric indices over the last 1000 years (Crowley footnote ref.), a low correlation that is shared by coupled model experiments (Delworth citation)? In fact, sediment core data from the subtropical North Atlantic often cited as indicative of a distinct “Medieval Warm Period” and “Little Ice Age” (Keigwin Sargasso Sea), has recently been shown to be more consistent with changes in the North Atlantic Oscillation (Keigwin and Pickart), implying a zero sum pattern of regionally alternating warm and cold superimposed on far more modest hemispheric variations over the past 1000 years. This pattern itself may be forced, rather than internal in nature, and would explain the limited evidence for more dramatic cold and warm periods in regions such as Europe (see Mann, Sci Perspective, 2000). The above arguments lead us to conclude that, although the conveyor may be changing, radiative forcing perturbations were primarily responsible for centennial-millennial changes in the last 1000 years, with attendant implications for interpretation of earlier Holocene oscillations (e.g, Denton and Karlen). Furthermore, the weight of evidence indicates that the late 20th century hemispheric warming is significantly greater than the Middle Ages.

Michael E. Mann

Thomas J. Crowley

__________________

> Professor Michael E. Mann

> http://www.evsc.virginia.edu/faculty/people/mann.html

Thomas L. Delworth

GFDL/NOAA e-mail: td@xxxxxxxxx.xxx

The next email (truncated) shows that the last few hundred to a thousand years are most relevant to potential future changes. In this email, it is wished that people read the IPCC. Agreed, especially how the models and reconstructions were used to attribute climate change. But most interesting is that there are concerns about the uncertainties about the reconstructions. This precedes M&M papers. The correspondence shows Mann’s concern with 2C millennial trends, and his opinion that such are not supported. Another note, is the comment of only 4 useful sites for reconstructions over the past thousand years. Most important is that this is 2001, and T.R. Karl states that “”we really need to show how the data prior to 1600 stands up. Some contend there are only 4 good sites in the first part of the record.”” It is ironic that Dr. Mann states “”But the claims we make (e.g. the anomalousness of recent warmth) are guided by the substantial uncertainties in the reconstructions, which of course take into account uncertainty due to increasingly sparse information back in time, and I have yet to see any legitimate argument that our reconstruction (or Phils, Toms, Keiths, etc.) is “wrong” within the context of the diagnosed uncertainties.”” This became one of the contentions of M&M. Further, the NAS report (North) concluded that reconstructions past about 1600 were too uncertain to be used conclusively. The opposite of Dr. Mann’s claim June 2001. Another quote shows that at this time the “hockey stick” is the basis for comparison and considered the final arbitrator “”It avoids the issue that the recent temperature increase is outside any estimates of natural variability without any forcings. What else is the warming due to? On p 14, it does not sum up the forcings and make a clear statement about the total. Nowhere does it say that the recent warming has to be because of an increase in heating.”” There is a lot of information in this email. I have not truncated it much. This is because this is an important time period, and the email links the historical events, and highlights their context. The “hockey stick” has won at this point. It was the measuring stick and was used in the TAR in an “unprecedented” manner.

From: Phil Jones p.jones@xxxxxxxxx.xxx

To: “Michael E. Mann” <mann@xxxxxxxxx.xxx>, Thomas R Karl Thomas.R.Karl@xxxxxxxxx.xxx

Subject: Re: NRC report on climate change

Date: Tue, 12 Jun 2001 08:46:36 +0100

Cc: trenbert@xxxxxxxxx.xxx,”Michael E. Mann” <mann@xxxxxxxxx.xxx>, rbradley@xxxxxxxxx.xxx,tom Crowley <tom@xxxxxxxxx.xxx>, mhughes@xxxxxxxxx.xxx,k.briffa@xxxxxxxxx.xxx, Folland Chris ckfolland@xxxxxxxxx.xxx
<x-flowed>

Dear All,

I’d just like to echo all the points made by Mike and Kevin. The logic behind saying that there isn’t enough paleo data before 1600 yet there may have been even early millennia which experienced warming of almost 2 C per millennium escapes me. As Kevin points out they have mixed up all the various factors that force climate on interannual to intermillennial timescales. One of the main points of IPCC is to synthesize the science, with particular reference to potential future changes. Changes in the distant past (glacial and deglaciation) are of less relevance to the 21st century because of differences in boundary conditions. The last few hundred to a thousand years are clearly more important to the near future. At least from my quick reading there seems no explicit reference to changes in the thermohaline circulation. Perhaps the paleo people on this list need to redouble their efforts to empahasize the importance of the last few thousand years, stressing absolute dating, calibration and verification. Another issue that is mixed up in the report (apart from the forcing) is spatial scales. I will try and address these at the Chicago meeting. What are the 4 useful sites ? I just hope in the US that people read the full IPCC reports and the summaries, rather than this hastily cobbled together document. I also hope that Europeans don’t read it. It has already got some air time here and may get some more with Bush here this week. Issues like star wars and capital punishment were commented upon whilst I came to work. Kyoto wasn’t mentioned.

Cheers

Phil

At 10:45 11/06/01 -0400, Michael E. Mann wrote:

Hi Tom,

Thanks for your message. I know how hard you worked to make the report as balanced as possible, and realize this experience must have been a bit frustrating for you, after all the careful and hard work you and Chris put into our IPCC chapter. While the idea that the limited panel involved in the NAS report can provide an improved or more objective assessment of the science relative to IPCC seems, of course, ridiculous to a lot of us. But I’m very thankful you were on the panel. Needless to say, my criticism below is in no way directed towards you, but rather some of the other panel members whom I think did a real injustice to the science.

Having seen the list of authors and reviewers of the report, I think I have a pretty good idea what the source of a good deal of that skepticism is and I think much of it is spurious and unfair. There are legitimate caveats and uncertainties–I think we’ve been very honest about these in our publication, and we (as Phil, Keith, and others) are working earnestly to improve the reconstructions. But the claims we make (e.g. the anomalousness of recent warmth) are guided by the substantial uncertainties in the reconstructions, which of course take into account uncertainty due to increasingly sparse information back in time, and I have yet to see any legitimate argument that our reconstruction (or Phils, Toms, Keiths, etc.) is “wrong” within the context of the diagnosed uncertainties. Unfortunately, much of the criticsm that has been advanced recently is knee-jerk and unsubstantiated, particularly with regard to dendroclimatological issues (which Malcolm and Keith can comment on best). Much of this has to do w/ a lack of understanding of tree ring information (to be honest Tom, I didn’t see one name in the list of authors or reviewers of the NAS report whom I think is qualified to comment on dendroclimatological climate reconstruction and its strengths and weaknesses, and that is a real problem. In such a vaccum it is easy, for example, for Wally to wave around some highly non-standard, un peer-reviewed tree-ring analysis that he has been promoting (which Ed Cook himself, a co-author on this, admits makes use of a questionable standardization approach), in an attempt to dismiss all other climate reconstructions which use tree ring information. The criticism that there are only “4 useful sites” for reconstructing climate over the past 1000 years is especially irksome and ignorant. Does Tom C. agree that there are only 4 meaningful records that contribute to his reconstruction? Does Phil, or Keith? Where does that number come from? The same source as R.L.’s GHG sensitivity factor of 1.0 (i.e., the ether) I suspect.

The discussion of paleo in the report (which I realize you had very limited control over) is disturbingly misleading and flawed to many of us who actually work in this area. There are throwaway statements about millennial trends of 2 C in global temperatures being typical during the early Holocene that have no basis in fact. They are again probably based on this increasingly disturbing notion that Arctic ice core borehole thermometry or other ice core information tells us anything at all about the hemisphere let alone globe. A small number of scientists are really misleading the scientific community in this regard. How odd that the panel was happy to claim that there were millennial periods with 2 degree C warming in global temperature during the holocene (for which there is no reliable empirical evidence whatsoever) and yet focuses its skepticism on much more detailed and careful assessments of the most recent millennium. I think you can see why some of us are frustrated by this type of inconsistency, and suspect some degree of bias or agenda at work. There was a clear bias in the panel in the promotion of ice cores (which sample a very limited portion of the globe and are very questionable in their ability to say *anything* about hemispheric or global temperature variations). I am disturbed by this because the NAS report shouldn’t have been promoting a particular specific area of funding. It seems to have.

Finally, with regard to one of the primary supposed discrepancies in the paleo record of the past 1000 years, temperature reconstructions from boreholes vs. other proxies, I’ll be presenting some results in Chicago which I think you’ll all find quite elucidating. Turns out there is no discrepancy after all. More on that soon. I’ll also try to confront both the “real” and “imagined” sources of uncertainty and bias in paleoreconstructions in my presentation there, and we should all be able to have a very healthy discussion of this.

I really think that there was a bias in this panel which cannot be considered representative of the community as a whole. So I vote that we not over-react. I’m anxious to see Lindzen, Broecker, or Mike Wallace publish a peer-reviewed critical analysis of proxy data over the past 1000 years. Until that day, I take their comments w/ a shaker of salt…

mike
>At 09:41 AM 6/11/01 -0400, Thomas R Karl wrote:

>>Kevin,
>>
I agree with most of your points. It was a very interesting Panel. I should emphasize however, that the Paleo record (at least the last 1000 years) has many critics, and we really need to show how the data prior to 1600 stands up. Some contend there are only 4 good sites in the first part of the record. I am not sure of this, perhaps Mike and others will explain this in Chicago.

Regards, To
>>Kevin

Trenberth wrote:>>

>> > FYI

>> > Some comments on the NRC/NAS report on the IPCC and global warming >
>> > Kevin Trenberth 6/7/2001

While the report overall is an endorsement of the IPCC report and the process, it has a lot of “buts” in it, and the overall tone is to somewhat downplay the problem. It does not focus on policy relevant issues. The report was done in a very hurried fashion and perhaps as a result, there are several factual errors or misstatements and there are errors of omission. My impression is that it tends to overstate the caveats and need for questioning of results and understate the certainties and likelihoods. 1. In dealing with natural variability, there are two aspects that are mixed in this report. There is natural variability of climate that is tied to external forcings, such as variations in the sun, volcanoes, and the orbital variations of the Earth around the sun. The latter is the driver for the major ice ages and interglacials. The second kind of natural variability is that internal to the climate system arising from interactions between the atmosphere and ocean, such as El Nino, for instance. This variability occurs even in an unchanging climate. In the section dealing with this and in the summary, both kinds of variability are discussed as if they are the second kind. Glacial to interglacial differences are discussed without any mention of the known causes and as if these can happen without a cause. This is misleading at best. A consequence is that there is no clear statement that the recent warming is outside the realm of natural variability – and that a cause is needed. And the cause is human induced changes in the atmospheric composition. 2. The report does not clearly address issues in attribution of recent climate change to human activities. At the end of p 3 in the summary it makes an equivocal statement. It avoids the issue that the recent temperature increase is outside any estimates of natural variability without any forcings. What else is the warming due to? On p 14, it does not sum up the forcings and make a clear statement about the total. Nowhere does it say that the recent warming has to be because of an increase in heating. This reasoning also put limits on how large aerosol cooling can be. On p 17, the ambiguity over the term “natural forcing” is used to say that a causal link can not be unequivocally established. It does not mention estimates of variability from the paleo record and how well they agree (or not) with model estimates. It does not note on p 17 that many models show the signal of greenhouse gas effects emerging from the noise of natural variability about 1980. The attribution statement is weak.

…………………………………………..

>> > —————

>> > Kevin E. Trenberth e-mail: trenbert@xxxxxxxxx.xxx

>_______________________________________________________________________

> Professor Michael E. Mann

Prof. Phil Jones

Next is a very truncated email. The part that is interesting is the coupling of reconstructions with modeling. Except for special cases, further examples are not necessary to show that proxy data and models were used as it is indicated in the IPCC reports.

From: “Michael E. Mann” mann@xxxxxxxxx.xxx

To: Hans von Storch Hans.von.Storch@xxxxxxxxx.xxx

Subject: Re: EOS report

Date: Tue, 03 Jul 2001 15:04:58 -0400

Cc: “Michael E. Mann” <mann@xxxxxxxxx.xxx>, Julie Jones <jones@xxxxxxxxx.xxx>, Julia Cole <jcole@xxxxxxxxx.xxx>, rbradley@xxxxxxxxx.xxx, jto@u.arizona.edu, weber@xxxxxxxxx.xxx, wanner@xxxxxxxxx.xxx, tom crowley <tom@xxxxxxxxx.xxx>, k.briffa@xxxxxxxxx.xxx, Martin Widmann Martin.Widmann@xxxxxxxxx.xxx

>>>If you mean ‘forward modelling’, by what I term upscaling, this is done

>>>in exactly the same way as most other climate reconstructions,

>>>i.e. calibrating proxy data against climate data using linear multivariate

>>>statistical methods (in this case I use CCA), so has the same errors

>>>inherent in it as other reconstructions where proxy data has been

>>>calibrated against large-scale climate, or climate indices.

>>>

>>>If your idea is that such large-scale climate reconstructions may have

>>>additional uncertainties compared to local empirical models, where proxy

>>>data are calibrated against local climate records, I agree that this is

>>>so – but I think this applies to all such non-local reconstructions, so

>>>should maybe go in the paragraph which discusses reconstructions of

>>>regional climate variability to keep things consistent.

>>>

>>>cheers

>>>

>>>Julie

>>>

>>>************************************

>>>Dr. Julie M. Jones

The next is a lengthy email concerning support of the MWP and different proxy reconstructions. The reading makes it obvious that the amplitude does matter (the shaft not the blade). It also appears that Dr. Mann’s concern is the support for the IPCC. Without a doubt it shows that for Dr. Mann’s part, weakening of the claim of warmest in the millennia was to be contested. The exchanges also indicate that there are potentially serious problems with reconstructions back a thousand years. It also reveals that these scientists are serious about their work. There are so many great quotes here; I think this one will be popular. Dr. Briffa definitely is not backing down about the science. One showing why it is so important that the MWP and shaft stay as in MBH is this quote “…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….” Another great quote is “We can, of course, argue about what this means for the pre-1400 part of your reconstruction, when only 1 EOF was reconstructed…” Another showing that Dr. Briffa is determined “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.” But the quote for the Yamal debate is this one: “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.” This is the bone of contention that if reconstructions are not independent but that reconstructions based on Yamal, strip bark etc, are flawed, then the shaft no longer is a shaft and that infamous quote in 4AR that one cannot get the CWP without using CO2 is unsupportable. The science ends up going back to the SAR where it was determined that man was influencing the climate, not causing catastrophic destruction.

One quote that deserves special emphasis is this one:

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.

This is hardly the cry that will instill confidence in sacrificing modern civilization, but this is 2002 and that is the public claim. If anything shows through in these posts is that there is a whole lot less consensus and certainty than what they are telling policy makers. Now that critics are showing that the concerns of Dr. Briffa and others are legitimate, public revelation that this was already known will be a decided sore point that skeptics with an axe to grind will probably make good and often use. Remember this is the TAR with the claim of “the unprecedented late 20th century warming’ being used to drive policy. And, of course, with “An Inconvenient Truth”, it became the rallying cry for the necessity of remaking the modern industrial world.

But where do we go if Yamal and MBH are so flawed? We go back to the SAR. The statement accepting everything is preliminary and should be treated with caution was not given to the policy makers and the public. This statement becomes problematic when one considers what is just over the time horizon: McIntyre and McKitrick. If it is known that the tree rings form the backbone for the hemispheric temperature estimates exist with uncertainties and should be treated with considerable caution, then why was there such a negative reaction when M&M confirmed their suspicions voiced in this email? In hindsight, the “moving on” that the “Team” has been labeled with by McIntyre appears to be valid description. The problem is that while claiming that “peer reviewed” is the gold standard, the truth shown in the emails is that they gamed the system. From WSJ to WUWT, the gaming has been documented. So on the one hand, they will fight M&M by criticizing E&E, all the while trying to prevent a discussion in the peer reviewed literature that they knew from this email to be potentially, if not certainly, valid!

From: Keith Briffa k.briffa@xxxxxxxxx.xxx

To: “Michael E. Mann” <mann@xxxxxxxxx.xxx>, p.jones@xxxxxxxxx.xxx, tcrowley@xxxxxxxxx.xxx, rbradley@xxxxxxxxx.xxx, mhughes@xxxxxxxxx.xxx, drdendro@xxxxxxxxx.xxx, rkerr@xxxxxxxxx.xxx, bhanson@xxxxxxxxx.xxx

Subject: Re: Briffa & Osborn piece

Date: Fri Apr 5 17:17:55 2002

Cc: Tim Osborn t.osborn@xxxxxxxxx.xxx

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)

At 12:39 PM 3/22/02 -0500, Michael E. Mann wrote:

Keith and Tim,

Sadly, your piece on the Esper et al paper is more flawed than even the paper itself. Ed, the AP release that appeared in the papers was even worse. Apparently you allowed yourself to be quoted saying things that are inconsistent with what you told me you had said. You three all should have known better. Keith and Tim: Arguing you can scale the relationship between full Northern Hemisphere and extratropical Northern Hemisphere is *much* more problematic than even any of the seasonal issues you discuss, and this isn’t even touched on in your piece. The evidence of course continues to mount (e.g., Hendy et al, Science, a couple weeks ago) that the tropical SST in the past centuries varied far more less in past centuries. Hendy et al specifically point out that there is little evidence of an LIA in the tropics in the data. The internal inconsistency here is remarkably ironic. The tropics play a very important part in our reconstruction, with half of the surface temperature estimate coming from latitudes below 30N. You know this, and in my opinion you have knowingly misrepresented our work in your piece. This will be all be straightened out in due course. In the meantime, there is a lot of damage control that needs to be done and, in my opinion, you’ve done a disservice to the honest discussions we had all had in the past, because you’ve misrepresented the evidence. Many of us are very concerned with how Science dropped the ball as far as the review process on this paper was concerned. This never should have been published in Science, for the reason’s I outlined before (and have attached for those of you who haven’t seen them). I have to wonder why the functioning of the review process broke down so overtly here,

Mike

_______________________________________________________________________

Professor Michael E. Mann

e-mail: mann@xxxxxxxxx.xxx Phone: (434) 924-7770 FAX: (434) 982-2137

[1]http://www.evsc.virginia.edu/faculty/people/mann.shtml

Professor Keith Briffa,

1. http://www.evsc.virginia.edu/faculty/people/mann.shtml

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

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

From: “Michael E. Mann” mann@xxxxxxxxx.xxx

To: Ed Cook drdendro@xxxxxxxxx.xxx

Subject: Re: Your letter to Science

Date: Fri, 12 Apr 2002 17:35:33 -0400

Cc: Malcolm Hughes <mhughes@xxxxxxxxx.xxx>, Malcolm Hughes <mhughes@xxxxxxxxx.xxx>, esper@xxxxxxxxx.xxx, k.briffa@xxxxxxxxx.xxx, t.osborn@xxxxxxxxx.xxx, p.jones@xxxxxxxxx.xxx, tcrowley@xxxxxxxxx.xxx, rbradley@xxxxxxxxx.xxx, jto@u.arizona.edu, srutherford@xxxxxxxxx.xxx

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 full Northern 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

Email: drdendro@xxxxxxxxx.xxx

Professor Michael E. Mann

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Dr. Edward R. Cook

Email: drdendro@xxxxxxxxx.xxx

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Professor Michael E. Mann

e-mail: mann@xxxxxxxxx.xxx Phone: (434) 924-7770FAX: (434)

982-2137

[2]http://www.evsc.virginia.edu/faculty/people/mann.shtml

Malcolm Hughes

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Dr. Edward R. Cook

_______________________________________________________________________

Professor Michael E. Mann

References

1. http://www.evsc.virginia.edu/faculty/people/mann.sht

2. http://www.evsc.virginia.edu/faculty/people/mann.shtml

3.http://www.evsc.virginia.edu/faculty/people/mann.shtml%A0%A0%A0%A0%A0%A0%A0%A0%A0%A0%A0%A0

4. http://www.evsc.virginia.edu/faculty/people/mann.shtml

5. http://www.evsc.virginia.edu/faculty/people/mann.shtml

From: “Michael E. Mann” mann@xxxxxxxxx.xxx

To: Tim Osborn <t.osborn@xxxxxxxxx.xxx>, Ed Cook drdendro@xxxxxxxxx.xxx

Subject: Re: Your letter to Science

Date: Mon, 15 Apr 2002 12:44:53 -0400

Cc: Malcolm Hughes <mhughes@xxxxxxxxx.xxx>, esper@xxxxxxxxx.xxx, k.briffa@xxxxxxxxx.xxx, p.jones@xxxxxxxxx.xxx, tcrowley@xxxxxxxxx.xxx, rbradley@xxxxxxxxx.xxx, jto@u.arizona.edu, srutherford@xxxxxxxxx.xxx, mann@xxxxxxxxx.xxx
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 underestimate 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 first 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

The next email of May 2003 concerns the Soon and Baliunas paper. I have left the header so it can be looked up, and will have selected quotes that pertain to the discussion of the MWP and models. From K. Briffa:

1.) As Tom W. states, there are uncertainties and “difficulties” with our current knowledge of Hemispheric temperature histories and valid criticisms or shortcomings in much of our work. This is the nature of the beast – and I have been loathe to become embroiled in polarised debates that force too simplistic a presentation of the state of the art or “consensus view”.

2.) The one additional point I would make that seems to have been overlooked in the discussions up to now, is the invalidity of assuming that the existence of a global Medieval Warm period, even if shown to be as warm as the current climate , somehow negates the possibility of enhanced greenhouse warming. The business of constructing a reliable climate history is only one part of establishing the relative roles of natural and anthropogenic forcings, now and in the future. Without reference to the roles of natural forcings in recent and past times, comparisons with other periods are of very limited value anyway.

3.) From Tom W: While many of the criticisms are invalid, and some are irrelevant, there are a number that seem to me to be quite valid. Probably, most of these can be rebutted, and perhaps some of these are already covered in the literature. In my view, however, there a small number of points that are valid criticisms ….. The real issue that the press (to a limited extent) and the politicians (to a greater extent) have taken up is the conclusions of the paper’s original research. First, Soon et al. come down clearly in favor of the existence of a MWE and a LIA. I think many of us would agree that there was a global-scale cool period that can be identified with a LIA. The MWE is more equivocal. There are real problems in identifying both of these ‘events’ with certainty due to (1) data coverage, (2) uncertainty in transfer functions, and (3) the noise of internally generated variability on the century time scale. [My paper on the latter point is continually ignored by the paleo community, but it is still valid.] So, we would probably say: there was a LIA; but the case for *or against* a MWE is not proven.

From: Keith Briffa k.briffa@xxxxxxxxx.xxx

To: “Michael E. Mann” <mann@xxxxxxxxx.xxx>, Tom Wigley <wigley@xxxxxxxxx.xxx>, Phil Jones\ <p.jones@xxxxxxxxx.xxx>, rbradley@xxxxxxxxx.xxx

Subject: Re: Soon et al. paper

Date: Tue May 20 16:07:41 2003

Cc: Jerry Meehl <meehl@xxxxxxxxx.xxx>, Caspar Ammann <ammann@xxxxxxxxx.xxx>, mann@xxxxxxxxx.xxx

The next one is sure to be in a post sometime soon, I predict. It is Oct 30, 2003 and Dr. Mann is asking his colleagues to look at a paper by McIntyre and McKitrick (E&E 14, 751-771). The following quote is most interesting when one compares it with the Wegman and North reports:

It is unfortunate that the profound errors, and false and misleading statements, and entirely spurious results provided in the McIntyre and McKitrick article were ever allowed to see the light of day by those would have been able to detect them. …. Not only were critical errors made in their analysis that render it thoroughly invalid, but there appear to have been several strikingly subjective decisions made to remove key indicators of the original MBH98 network prior to AD 1600, with a dramatic impact on the resulting reconstruction. It is precisely the over which the numerous indicators were removed (pre 1600 period) during which MM reconstruct anomalous warmth that is in sharp opposition to the cold conditions observed in MBH98 and nearly all other independent published estimates that we know of. …

And much more. Fast forward to today. The successful challenge to the claim of independent, the validation of M&M, the Jesus paper, etc. And of course, the stacking of peer review against skeptics while holding up peer-reviewed as the gold standard requirement. The most damning thought is what if Dr. Mann had been able to stop M&M? Would we already be going down a path of unbelievable costs with an unknown, even small chance of success?

From: “Michael E. Mann” mann@xxxxxxxxx.xxx

To: “raymond s.bradley” <rbradley@xxxxxxxxx.xxx>, mhughes@xxxxxxxxx.xxx, “Phil Jones” <p.jones@xxxxxxxxx.xxx>, Keith Briffa <k.briffa@xxxxxxxxx.xxx>, Tim Osborn <t.osborn@xxxxxxxxx.xxx>, mann@xxxxxxxxx.xxx, Scott Rutherford srutherford@xxxxxxxxx.xxx

Subject: Can you believe it???

Date: Thu, 30 Oct 2003 09:02:53 -0500

Guys, can you take a look at this. I think that everything I say here is true! But we’ve got to be sure. There are more technical things they did wrong that I want to add, but this is the critical bit–what do you think. Comments? Thanks…

mike
________________________________________

The recent paper by McIntyre and McKitrick (Energy and Environment, 14, 751-771) claims to be an “audit” of the analysis of Mann, Bradley and Hughes (1998) or “MBH98″. An audit involves a careful examination, using the same data and following the exact procedures used in the report or study being audited. McIntyre and McKitrick (“MM”) have done no such thing, having used neither the data nor the procedures of MBH98. Their analysis is notable only in how deeply they have misrepresented the data, methods, and results of MBH98. Journals that receive critical comments on a previously published papers always provide the authors who are being criticized an opportunity to review the study prior to publication, and offer them the chance to respond. This is standard operating procedure in any legitimate peer-reviewed scientific journal. Mann and colleagues were never given this opportunity, nor were any other leading paleoclimate scientists that we’re familiar with. It is unfortunate that the profound errors, and false and misleading statements, and entirely spurious results provided in the McIntyre and McKitrick article were ever allowed to see the light of day by those would have been able to detect them. . We suspect the extremely checkered history of “Energy and Environment” has some role to play in this. The authors should retract their article immediately, and issue a public apology to the climate research community for the injustice they have done in publishing and promoting this deeply deceptive and flawed analysis.

Not only were critical errors made in their analysis that render it thoroughly invalid, but there appear to have been several strikingly subjective decisions made to remove key indicators of the original MBH98 network prior to AD 1600, with a dramatic impact on the resulting reconstruction. It is precisely the over which the numerous indicators were removed (pre 1600 period) during which MM reconstruct anomalous warmth that is in sharp opposition to the cold conditions observed in MBH98 and nearly all other independent published estimates that we know of.

While the authors dutifully cite the small inconsistency between the number of proxy indicators reported by, and found in the public data archive, of Mann et al back in time (there indeed appear to have been some minor typos in the MBH98 paper), it is odd that they do not cite the number of indicators in their putative version of the Mann et al network based on the independent collection of data, back time. The reader is literally left to do a huge amount of detective work, based on the tables in their pages 20-23, to determine just what data have been eliminated from the original Mann et al network. It seems odd, indeed, that their “substitutions” of other versions (or in some case, only apparent, and not actual, versions) of proxy data series for those in the original Mann et al (1998) network has the selective effect of deleting key proxy indicators that contribute dramatic cooling during the 16th century, when the MM reconstruction shows an anomalous warming departure from the Mann et al (1998) and all other published Northern Hemisphere temperature reconstructions.

Here are some blatant examples:

1) The authors (see their Figure 4) substitute a younger version of one of the Jacoby et al Northern Treeline series for the older version used by MBH98. This substitution has effect of removing a predictor of 15th century cooling [Incidentally, MM make much of the tendency for some tree ring series, such as this one, to show an apparent cooling over the past couple decades. Scientists with expertise in dendroclimatology know that this behavior represents a decrease in the sensitivity to temperature in recent decades that likely is related to conditions other than temperature which are limiting tree growth]

2) The authors eliminate, without any justification, the entire dataset of 70 Western North American (WNA) tree-ring series available between 1400 and 1600 (this dataset is represented, by MBH98, in terms of a smaller number of representative Principal Component time series). The leading pattern of variance in this data set exhibits conditions from 1400-1800 that are dramatically colder than the mid and late 20th century, and a very prominent cooling in the 15th century in particular. The authors eliminated this entire dataset because they claimed that the underlying data was not available in the public domain.

In point of fact, not only were the individual WNA data all available on the public ftp site provided by Mann and colleagues:

[1]ftp://holocene.evsc.virginia.edu/pub/MBH98/TREE/ITRDB/NOAMER/, but they were also available, despite the claims to the contrary by MM, on NOAA’s website as well:

2]ftp://ftp.ngdc.noaa.gov/paleo/treering/chronologies/northamerica/usa

The deletion of this critical (see Mann et al, 1999) dataset appears to one of the more important censorings performed by MM that allows them to achieve their spurious result of apparent 15th-16th century warmth. We have not, as yet, finished determining just how many important indicators were subtly censored from the MBH98 dataset by the various subjective substitutions described on pages 20-23. However, given the relatively small number of indicators available between 1400-1500 in the MBH98 network (22-24) and their elimination of some of the more critical ones, it would appear that this subjective censoring of data, alone, explains the spurious, misleading, and deceptive result achieved by the authors.
Incidentally, MBH98 go to great depths to perform careful cross-validation experiments as a function of increasing sparseness of the candidate predictors back in time, to demonstrate statistically significant reconstructive skill even for their earlier (1400-1450) reconstruction interval. MM describe no cross-validation experiments. We wonder what the verification resolved variance is for their reconstruction based on their 1400-1450 available network, during the independent latter 19th century period?
There are numerous other serious problems that would render the MM analysis completely invalid, even in the absence of the serious issue raised above, and these are detailed below
.
.
.

______________________________________________________________

Professor Michael E. Mann

References

1. ftp://holocene.evsc.virginia.edu/pub/MBH98/TREE/ITRDB/NOAMER/

2. ftp://ftp.ngdc.noaa.gov/paleo/treering/chronologies/northamerica/usa

3. http://www.evsc.virginia.edu/faculty/people/mann.shtml

Next is some correspondence about Ch6 Climate Sensitivity with linking models and sensitivity as was explored in previous posts about Yamal. Some interesting discussion of uncertainties and other considerations.

From: Stefan Rahmstorf regentage@xxxxxxxxx.xxx

To: Eystein Jansen eystein.jansen@xxxxxxxxx.xxx

Subject: [Wg1-ar4-ch06] Ch6-Climate Sensitivity

Date: Fri, 01 Oct 2004 11:49:05 +0200

Reply-to: stefan@xxxxxxxxx.xxx

Cc: wg1-ar4-ch06@xxxxxxxxx.xxx

Hi co-authors,

here are some thoughts on what to say on climate sensitivity in our chapter – this is an attempt to focus on the main, simple messages for policy makers. (I think we should try retaining those important messages and not lose sight of them amidst all the details, complexity and caveats.) The main policy-relevant question could be phrased as follows: Does the past climate history tell us how sensitive the climate system is to CO2? I submit that the answers to this we get from different time periods are the following. Deep Time: Reconstructions are too uncertain (and boundary conditions too different, e.g. continents in different places, different ocean circulation) to draw quantitative conclusions about sensitivity to CO2, but there is clear evidence that times of high CO2 in Earth history tend to be ice free (Royer et al. 2004). A second piece of evidence is the Late Paleocene Thermal Maximum, which shows that the climate has responded by warming to a large carbon release into the atmosphere. Just how large this carbon release was is not known, since several origins of the carbon are possible, which have different isotope signature and would thus imply different amounts. But the temperature response was large (6K), and if anything this response would point to a high sensitivity. Glacial-Interglacial Changes: We have by now sufficiently good quantitative reconstructions of CO2 and other forcings as well as temperatures in order to derive useful quantitative estimates of climate sensitivity. LGM was the most recent time in history in which CO2 concentration differed greatly from pre-industrial values, by as much as it does now. It is the closest test case for response to CO2 changes that we have. There are two basic methods to derive climate sensitivity:

(i) Based on data analysis – e.g. Lorius et al. 1991 (concluding sensitivity is 3-4 K). This method has the caveat that this sensitivity applies to colder climate, which may differ somewhat from that which applies in present climate as the strength of feedbacks is expected to depend on the mean climate (e.g., stronger snow-albedo feedback in colder conditions).

(ii) Based on combining data and models – e.g. Schneider von Deimling et al. 2004. Does not have the above caveat, but depends on models. Lag of CO2 behind temperature does not imply a lack of CO2 effect on climate, since the lag is small (centuries, not millennia). Holocene, last millennium??

Overall conclusions

Qualitatively, climate history is at least consistent with the accepted CO2 sensitivity. There is no evidence for much lower or much higher CO2 sensitivity (note that CO2 is not the only forcing). The more recent climate history (as far back as ice core data go) does allow quantitative inferences. The results of these estimates all lie within the IPCC range and provide strong support for this. Paleodata may even allow to reduce this range, since at least one study argues that values above 4K are very likely inconsistent with the reconstructed LGM climate: for high CO2 sensitivity, tropical cooling in the glacial should have been larger.

Cheers,

Stefan
_______________________________________________ Wg1-ar4-ch06 mailing list
Wg1-ar4-ch06@xxxxxxxxx.xxx http://www.joss.ucar.edu/mailman/listinfo/wg1-ar4-ch06

Here there is one quote worth mentioning the header has been saved. It is about the divergence problem which at this point has been a minor issue to the “Team”. It become much more:

From: Keith Briffa k.briffa@xxxxxxxxx.xxx

To: v.jones@xxxxxxxxx.xxx

Subject: first go

Date: Tue Nov 23 16:01:56 2004

Cc: v.shishov@xxxxxxxxx.xxx

I think the “hook” needs to be the important opportunity to assess recent changes in lake and tree productivity and see if any evidence for response to climate , as well as searching for unprecedented evidence of climate change. I realise this is predominantly a lake project with a link to trees and models , but the links must be more than token . I can provide more background as to where we are with tree-ring work in Euro-Siberia if needed . I think the model stuff also needs specific justification . Is Simon going to contribute here? Don’t get hung up on the “decline or changing sensitivity issue” in trees . This is NOT a great problem in Scandinavia, Ural/Yamal and is anyway a divergence in trend and quite subtle and evident in wood density mostly. We are also of the opinion that it could be partly a statistical processing artifact – we are exploring this now.

cheers

Keith

References

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

The next piece is another historical email. I think Steve and Ross will be posting shortly whether this is their email that got some of the Team all excited over. It is disappointing to see that old tar brush of being a shill of some sort. It really detracts from the science.

From: Phil Jones p.jones@xxxxxxxxx.xxx

To: t.osborn@xxxxxxxxx.xxx,k.briffa@xxxxxxxxx.xxx

Subject: Fwd: Re: Fw: Rutherford et al. [2004]

Date: Tue, 04 Jan 2005 11:22:31 +0000
FYI.

Just look at the attachment. Don’t refer to it or send it on to anybody yet. I guess you could refer to it in the IPCC Chapter – you will have to some day !

Cheers

Phil

X-Sender: mem6u@xxxxxxxxx.xxx

X-Mailer: QUALCOMM Windows Eudora Version 6.1.1.1

Date: Thu, 30 Dec 2004 09:22:02 -0500\

To: Phil Jones p.jones@xxxxxxxxx.xxx

From: “Michael E. Mann” mann@xxxxxxxxx.xxx

Subject: Re: Fw: Rutherford et al. [2004]

X-UEA-MailScanner-Information: Please contact the ISP for more information
X-UEA-MailScanner: Found to be clean

X-UEA-MailScanner-SpamScore: s

Phil,

I would immediately delete anything you receive from this fraud. You’ve probably seen now the paper by Wahl and Ammann which independently exposes McIntyre and McKitrick for what it is–pure crap. Of course, we’ve already done this on “RealClimate”, but Wahl and Ammann is peer-reviewed and independent of us. I’ve attached it in case you haven’t seen (please don’t pass it along to others yet). It should be in press shortly. Meanwhile, I would NOT RESPOND to this guy. As you know, only bad things can come of that. The last thing this guy cares about is honest debate–he is funded by the same people as Singer, Michaels, etc… Other than this distraction, I hope you’re enjoying the holidays too… talk to you soon,

mike
At 09:02 AM 12/30/2004, you wrote;
Mike,

FYI. Just in for an hour or so today as still off until Jan 4. Not replied to this – too much else with IPCC etc. Not read this in detail – just printed it off.

Have a good New Year’s Eve.

Cheers

Phil

From: “Steve McIntyre” stephen.mcintyre@xxxxxxxxx.xxx

To: “Phil Jones” p.jones@xxxxxxxxx.xxx

Subject: Fw: Rutherford et al. [2004]

Date: Wed, 29 Dec 2004 10:08:18 -0500

X-Mailer: Microsoft Outlook Express 6.00.2800.1158 X-UEA-MailScanner-Information: Please contact the ISP for more information X-UEA-MailScanner: Found to be clean

Dear Phil,

I have noticed the following statements in Rutherford et al [2004], in which you are a co-author. As compared with some of your co-authors, I get the impression that, while you feel very strongly about your views, you are also concerned with getting to the bottom of matters and are less concerned with scoring meaningless debating points. In this spirit, I draw your attention to some incorrect statements in Rutherford et al. [2004] concerning our material. There is really a quite serious problem with the PC methods in MBH98 and the comments made in Rutherford et al [2004] are really quite misleading. For the reasons set out below, I request that these comments be removed from the manuscript.
Regards, Steve McIntyre

—– Original Message —–

From: [1]Steve McIntyre

To: [2]David Randall

Cc: [3]Scott Rutherford ; [4]Paul Kushner ; [5]Cindy Carrick ; [6]Ross McKitrick

Sent: Tuesday, December 28, 2004 1:48 PM

Subject: Rutherford et al. [2004]

Dear Dr. Randall,
Recently, at the website [7]www.realclimate.org, Michael Mann publicized a submission by Rutherford et al. to Journal of Climate, entitled Proxy-based Northern Hemisphere Surface Temperature Reconstructions: Sensitivity to Method, Predictor Network, Target Season, and Target Domain. This paper contains some untrue statements and mischaracterizations regarding criticisms we (McIntyre and McKitrick) made of Mann et al. (1998) [MBH98] in a 2003 paper and subsequent exchanges under the auspices of Nature. We are writing to request that these untrue statements be removed from the paper before any further processing of the document by Journal of Climate takes place.
First, Rutherford et al. states that McIntyre and McKitrick [2003] used an incorrect version of the Mann et al. (1998) proxy indicator dataset. The history of this matter is summarized below (all relevant emails and other documentation are available at [8]http://www.climate2003.com/file.issues.htm .

In April 2003, we requested from Mann the FTP location of the dataset used in MBH98. Mann advised me that he was unable to recall the location of this dataset and referred the request to Rutherford. Rutherford eventually directed us to a file (pcproxy.txt) located at a URL at Manns FTP site. In using this data file, we noticed numerous problems with it, not least with the principal component series. We sought specific confirmation from Mann that this dataset was the one used in MBH98; Mann said that he was too busy to respond to this or any other inquiry. Because of the many problems in this data set, we undertook a complete new re-collation of the data, using the list of data sources in the SI to MBH98 and using original archived versions wherever possible. After publication of McIntyre and McKitrick [2003], Mann said that dataset at his FTP site to which we had been referred was an incorrect version of the data and that this version had been prepared especially for me; through a blog, he provided a new URL which he now claimed to contain the correct data set. The file creation date of the incorrect version was in 2002, long prior to my first request for data, clearly disproving his assertion that it was prepared in response to my request. Mann and/or Rutherford then deleted this incorrect version with its date evidence from his FTP site. It is false and misleading for Rutherford et al. to now allege that we used the wrong dataset. We used the dataset they directed us to at their FTP site. More importantly, for our analysis, to avoid the problems with the principal component series, we re-collated the tree ring data identified in MBH98 from ITRDB archives, calculated fresh principal component series; in addition, we re-collated other proxy data from archived versions wherever possible. Thus, our own calculations were not affected by the errors in the supplied file as we did NOT use the incorrect version in our calculations. To suggest otherwise, as is done in Rutherford et al [2004], is highly misleading. To date, no source code or other evidence has been provided to fully demonstrate that the incorrect version (now deleted) did not infect some of Manns and Rutherfords other work. In this respect, we note that the now deleted file pcproxy.txt occurs in a legend in a graphic at Rutherfords website, indicating possible use elsewhere by Rutherford of the incorrect version.
Accordingly, we request that the above claim be removed from the manuscript.

Secondly, Rutherford et al. [2004] argues that the difference between MBH98 results and MM03 results occurs because of our misunderstanding of a stepwise procedure in MBH98 for the calculation of principal component series for tree ring networks. Again, this claim is misleading on its face. While our 2003 paper did not implement the (then undisclosed) stepwise procedure, as soon as this matter was raised in subsequent correspondence in November 2003, we implemented it and we continued to observe the discrepancies in principal component series and final results. The current manuscript ignores a refereed exchange at Nature in which we specifically clarified (in response to a reviewers question) that we had obtained such results while using the exact stepwise procedure described in MBH98. Mann is aware of this refereed exchange.

The reason for the difference between our results and MBH98 results is primarily due to the fact that the tree ring principal component series in MBH98 cannot be replicated using a conventional principal components method. The MBH98 principal component series can only be replicated by standardizing on a short segment a procedure nowhere mentioned in MBH98 and only recently acknowledged in the SI to the Corrigendum of Mann et al. [Nature 2004] in response to our concerns on the subject expressed to Nature. In effect, MBH98 did not use a conventional centered PC calculation, but used an uncentered PC calculation on de-centered data. The impact of this method is the subject of ongoing controversy, which is well-known to the authors, but the existence of the method in MBH98 is no longer in doubt. In discussions of PC calculations in 2004 exchanged with the authors through Nature, we implemented the stepwise procedures of MBH98 referred to in the present manuscript and demonstrated that important differences remain even with stepwise procedures, as long as the uncentered and decentered methods of MBH98 are used. The differences in PC series resulting from using centered and uncentered series has been fully agreed to by all parties in the Nature exchange, although the parties continue to disagree on the ultimate effect on final NH temperature calculations. Accordingly, the discussion in Rutherford et al. [2004] is very incomplete and misleading in this respect. While we recognize that Mann et al. have argued that they can salvage MBH98-type results using alternative methodologies (e.g. increasing the number of PC series used in the 1400-1450 period), these salvage efforts are themselves a matter of controversy and do not validate the claims being put forward in the Rutherford et al. paper.

Accordingly we ask that this claim also be deleted from the manuscript.

Regards,

Stephen McIntyre and Ross McKitrick

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@xxxxxxxxx.xxx

NR4 7TJ

UK
—————————————————————————-

______________________________________________________________
Professor Michael E. Mann

Department of Environmental Sciences, Clark Hall

University of Virginia

Charlottesville, VA 22903

_______________________________________________________________________
e-mail: mann@xxxxxxxxx.xxx Phone: (434) 924-7770 FAX: (434) 982-2137

[9]http://www.evsc.virginia.edu/faculty/people/mann.shtml

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@xxxxxxxxx.xxx

NR4 7TJ

UK
—————————————————————————-

Attachment Converted: “c:documents and settingstim osbornmy documentseudoraattachWahl_MBH_Recreation_JclimLett_Nov22.pdf”
References

1. mailto:stephen.mcintyre@xxxxxxxxx.xxx

2. mailto:randall@xxxxxxxxx.xxx

3. mailto:srutherford@xxxxxxxxx.xxx

4. mailto:j.climate@xxxxxxxxx.xxx

5. mailto:cindy@xxxxxxxxx.xxx

6. mailto:rmckitri@xxxxxxxxx.xxx

7. http://www.realclimate.org/

8. http://www.climate2003.com/file.issues.htm

9. http://www.evsc.virginia.edu/faculty/people/mann.shtml

Conclusions: This is a long post that has just got to the point where the “Team” is being challenged. But it is a good stopping point. The historical perspective of Yamal is now established. We know what has happened. M&M break the “hockey stick.” In an effort to show independent support for unprecedented warmth they use a series (Yamal) that it is known that the number of replications are small and there appears to be a fertilization problem, or a problem with the best (longest lived) trees were known to have appeared to have been shadowed or influenced some way such that they did not grow uniformly. The non-uniformity violates the assumptions (homogeneity and stationary) necessary for comparing present growth with past. Even more problematic for Yamal and the reconstructions using it is that the area is known to be data rich. This underlines the concern of the limited numbers in the chronology. Further, the stonewalling of McIntyre, McKitrick, and others who point out problems that were known, but were denied or ignored by the dendro community and the use of cores for which it was determined at one time to be fertilization not temperature, cannot be made to look good. In the emails, it is apparent that it was known that the replication and number of chronologies were a problem. It was known that the standard deviations of ring width were a problem. It has been admitted by Dr. Briffa in a recent statement that they are working on some, if not all, of these problems. But the tense is a refutation of TAR and 4AR.

It is a refutation because these reconstructions were used to support the claim that the warming is unprecedented and that no model with natural forcings only could replicate the post 1950 warming. In the 4AR, the IPCC state that the warming past 1950 was assumed to be manmade. They conclude that this was very likely due the unprecedented warming and the models. This meme is repeated over and over again in the 4AR. Now that these conclusions of warming and anthropogenic cause are questioned, where does that leave the science? At the SAR, though some will claim that the models alone can be used. There are two problems with this. The first problem is that is not how the models were developed, and extrapolating models without checking against a backcast invites uncontrollable problems from initial values, as is documented in the literature. The thread on CA on exponential growth is a mustread. The second problem is a quote one can find all over the net, that models did not predict current temperatures; and it is a travesty that they didn’t.

So, we are at “man is influencing the climate”, not “catastrophic global warming.” To his credit, Monbiot seems to have a better handle on this than most. With all the posts and articles, it will not be long until it is confirmed just how far and how long the public and reporters were misled about the consensus and quality of the claims. The emails on just two words, the study still incomplete, show that the public statements are far from the private ones, and no amount of spin is going to change that. That M&M and others are showing that the problems are even worse than these scientists thought, while these same scientists were stonewalling these efforts of the critics, that could have made the science stronger, by gaming the very system they were publicly claiming was impartial, is beginning to sink in. Soon it will sink in, as more and more is made public, that the real problems with Yamal and stripbark, etc., have only been partially discussed. At that point, it will be apparent that the Wegman report may have been the most unappreciated work on climate change science, outside of McIntyre and McKitrick’s efforts.


39 Responses to “Context”

  1. Layman Lurker said

    John, thank you for the effort you have put into this. Between your probing of Yamal, AR4, and now the emails, you may know more about this subject then any other “outsider”.

  2. Brian B said

    Excellent context John.
    Two suggestions:
    1. I’m sure you know it’s a little rough here and there so a little editing would help.
    2. Format; tough to note when your comments begin and when others are writing. Perhaps your original formatting didn’t survive the transfer here to Air Vent.

    Exceptional integration of the history up until the destruction of the Hockey Stick especially when viewed in conjunction with Willis E’s history of his FOI sparring with the Team. And very fair toward many of the occasionally less than sympathetic people involved. Mann is unspeakably hopeless.

  3. Dan Hughes said

    A great job John.

    I have run across a long series of discussions about tree rings that took place on the ITRDBFOR listsev. Way outside my area but there seems to be some who are unsure about the use of tree rings as thermometers.

  4. Arnold said

    Wow, very good work at placing things in context. Seems to me that:

    1 – Briffa had been tottaly railroaded
    2 – Mann was the “real” leader of the team
    3 – Mann is very protective of his own work (Not only to scepticts but also respected colleges)
    4 – Appearently the IPCC was making the shots about baselines etc.
    5 – Mann was under a lot of preciour from IPCC and Sponsors of the projects
    6 – Nature magazine (for one) has the habbit of letting publicated authors that ar going to be criticised read it up front (Maybe a little bias from the magazine)

    Looks like a doomsday scenario. And they seem to become more and more paniced over time. Even though they know that there are a LOT of uncertanty they try with everything that they have to keep it from the public (because sceptics are the worst people you can find)

  5. Al said

    A plot of the Lang reconstruction and the original hockeystick would seem worth adding.

    The people who have been paying close attention know what they both look like, but they’re pretty starkly different.

    It would also seem worthwhile to discuss the GCM’s more directly. The current attempts still have problems recreating the warming of the 1940’s, and hindcast essentially unremitting sameness prior to the rise of carbon dioxide.

    The hockeystick fixes this by flattening the shaft. And the 1940’s get squashed too.

    Several of the recaps are dismissing the relevance as unimportant historical detail. But the historical data is the training and verification area for the climatological models – and garbage in leads to garbage out.

  6. [...] Pittman has found some interesting science in the Climategate emails: The treeline is an sensitive treemometer, since it is very sharply defined, a few kilometers [...]

  7. Annabelle said

    I found this article very difficult to red as it was not clear what are quotes form emails, and what are the writer’s own words.

    Woul it be possible to do a bit of re-formatting to make this clearer? A lot of work has gone into this but unless it is easier to read, many people (like me) will be put off reading it.

  8. mitchell porter said

    I strongly second the request for re-formatting, specifically that quotes from emails be indented. The patient reader can figure it out anyway, but just a small visual clean-up will add a lot of value.

  9. [...] Historical Perspective of Why Yamal Matters   [...]

  10. Kon Dealer said

    As a plant physiologist, the key statement in this is Briffa’s on “fertilisation”.
    Two fertilisation components have been co-rising with temperature during the late 19th and 20th centuries.
    1) Atmospheric CO2,
    2) Atmospheric nitrate deposition.

    Briffa clearly recognises that both these factors are going to have a marked (and unquantifiable) fertilisation effect on trees growing at the limit of their range.
    The question then is how to deconvolute the growth signals resulting from increased fertilisation from those due to increased temperature? The uncomfortable truth is that you can’t. The basic science has not been done, so Briffa’s concerns are swept under the carpet.

    Temperature is the only culprit.

  11. plazaeme said

    # 8 – Mitchell Porter:

    Quite so.

  12. Jeff Id said

    #10, yup.

  13. Wolfgang Flamme said

    At least I broke a personal record by wading half through this before giving up.
    There might have been some valid points in this piece of work but the author greatly succeeded in distracting me from any of them by abandoning any outline structure, inserting lengthy fullquotes, using bewildering overall segmentation and inconsistent formatting.

  14. Joe NS said

    An excellent summary. What is emerging now, in my opinion, is (1) how absolutely insupportable the claim that the “science is settled” has been from the TAR onwards, and (2) the apparent strategic success the Hockey Team has achieved in getting that notion out to their flacks in the MSM and fixing it in the minds of policy makers BEFORE the recent “unpleasantness, i.e., Climategate.

    We see that their strategy, whether it was thought through or not and deserves the description of strategy, is now paying off for the fraudsters. Carole Browner, for example, replying to questions about the emerging controversy by saying with complete insouciance that most experts agree that the science is settled (SIS), so why should I (meaning Obama) pay attention to the corruption worked by “three or four” bad apples. So the president is flying off to Copenhagen as if it is still November 16th and NOTHING unusual, to say no more, has come to light. Clearly the constant droning about peer-review credentialing is of a piece with seven years of tiresome “the science is settled” repetitions. It’s almost as if the mere words “the peer-reviewed science is settled” have become a scientific datum, like a tree ring’s width or an ice-core’s temperature gradient, as if it could be listed in a table alongside numbers representing real data and, in fact, marginalizing the data.

    Knowing what we do now, and especially in light of this superlative post, one can hardly escape concluding that, pari passu with the Team’s growing realization that their data and their handling of it were scarifyingly corrupt – for which we have M&M to thank most of all – the desperate necessity of establishing SIS as a [pseudo]fact before possible and, as we now know, inevitable exposure has been uppermost in their minds for some time.

    The indescribably sad thing is that the maneuver may have worked in the nick of time for the scoundrels.

  15. The Internet said

    “funding managers personally alert us that they believe the credibility of our field has been damaged”

    I, for one, would like to know who the funding managers are. If looking for the root of a problem, follow the money.

  16. John F. Pittman said

    Sorry for the lack of formatting. It disappeared. I actually spent several hours trying to format the emails in a nested fashion so the actally email and the history part of the email were obvious. I don’t know if editing would be possible or even that JeffID would, or should give me admin rights. Though it is tough reading, the posters so far have been getting the information, and drawing good conclusions. I did not mean to leave so much in there, but some of the quotes without context would be too much like cherry picking. I hope you understand.

  17. pdtillman said

    Good work, but (as others have noted) needs to be reformatted so that it’s clear which are your words and which sections are direct quotes.

    Thanks in advance,
    Pete Tillman

  18. KevinUK said

    John,

    This is an excellent thread. Like you and many others I have also been reading the emails starting from the oldest first right through to the latest. It’s quite re-assuring to see you document many of the same emails that I have also copied to friends as I thought they were significant. If you havent alreadt i sringy suggest you read Christopher Booker new book ‘The Real Global Warming Catastrophe’ as it documents and concurs (prior to the release of these CRU emails) much of what is contained in many of the emails. Unlike CRU the mails Christopher Booker’s book goes back prior to 1996 and discusses the Ben Santer’s ‘doctering’ of the SAR. Those who have read and fully digested the content of CRU emails can clearly see Ben Santer’s influence on the CRU climate scientists.

    IMO (though I’ve yet to find the definitive evidence) Bob Watson was the person responsible for enlisting the services of the CRU to help the climate modellers deal with the slating they got post the SAR for not being able to adequately account for natural climate variability. Shortly after the SAR CRU were given a large contract from which the Russians were paid to gather the Yamal and Taimyr data so that the models could be used to asses how well they could reproduce decadal and mult-decadal variations observed in the tree ring data. This showed that the models could only account for roughly 50% of the natural variability seen in the tree ring data. Its after this that the ‘hockey stick’ appeared and Michael Mann’s now known to be totally contrived (thanks to M&M) temperature reconstruction won out in the battle with Keith Briffa’s Yamal reconstruction. Mann’s pushing of his own reconstruction (and its subsequent defence to its death) above all the alternatives e.g. Briffa’s, Esper’s etc all of which are in the AR4 ‘spaghetti graph’ is very apparent within the CRU emails. You have very succinctly shown that following the ‘death of the hockey stick’ it has became increasing important to provide support to Briffa’s Yamal reconstruction in the event that Mann’s defence of his resurrected ‘hockey stick’ fails once more. As you have also quite rightly pointe dout the proxy reconstructions are vital to the GCMs as they are used to ‘run up’ the models prior to their ‘projections’ of positive feedback induced flights of fantasy of ‘catastophic climate change’.

    KevinUK

  19. KevinUK said

    John,

    One of the others things I forgot to mention that you don’t. Mike Hulme is implicated in several of the CRU emails. For those who don’t know (its mentioned in some of the emails), Mike Hulme went on to be become the founding director of the (well funded by the NERC) UK Tyndall Centre. Amongst its staff are are Myles Allen (well known climate alarmist) and Mike New, mentioned in the famous Harry Read me file as one of the developers CRU TS 2 along with several contributing authors to the IPCC AR4.

    http://www.tyndall.ac.uk/people/staff-list-with-pictures

    KevinUK

  20. NukemHill said

    I’m going to strongly echo the requests to reformat this. Here are my recommendations:
    1) blockquote the email exchanges;
    2) blockquote any longer quotes you extract from the messages themselves;
    3) re-organize the email exchanges so that they are in chronological order, with brief explanations, maybe like this:
    Briffa states on 9/2/97:

    blah, blah, blah….

    Mann responds on 9/5/97:

    blah, blah, blah….

    Mann follows up on 9/6/97:

    blah, blah, blah….

    Briffa responds to Mann on 9/10/97:

    blah, blah, blah….

    (Yes, I completely made those authors and dates up!)

    I think following a format like this would turn this into much more than a blog post. It becomes an article worthy of any online magazine wanting to get involved in unlayering the mess you’ve identified. It’s a brilliant piece of research. The presentation needs to make that accessible to the lay reader.

  21. NukemHill said

    #16, John Pittman–just saw your follow-up. I see you tried to format things. Obviously, WordPress ate something. I know that WordPress allows for Word-formatted documents to be submitted; so if you haven’t tried it that way, you might want to give it a shot. Clearly, Jeff needs to give you some sort of access rights, so it is ultimately up to him.

    I might be available for some editorial kibitzing, if you want an extra pair of eyes for any of this. Jeff, I’ll extend this offer to you, as well. I’ve got a Physics/Math BA, CS MA as a background (along with some writing chops), so I may be able to provide some technical perspective if needed. Then again, I might not. I may be completely full of stuff! ;-)

    If you want to contact me, email me at gregory at hillhaven dot info. Totally up to you.

  22. Jeff Id said

    Ok, I took a crack at reformatting this. Sorry for the problems. I think I screwed it all up in the copy somehow and didn’t realize how bad it was. I read the whole thing in the original format, copied an pasted it and did a quick check. It usually works better than this but this post even messed up the date order of other posts (probably due to some wierd HTML). That’s why it’s not a sticky post right now (black box).

    There have been a lot of family things this weekend to do and a half dozen reporters asking questions so I took care of that along with a few other details like Mann09, and some other posts. It’s just been a bit too much for one person.

    Let me know if this still has problems.

  23. Brian B said

    #22 Much better Jeff. Thank you.
    As I mentioned in #2 I figured the original formatting had not survived the move here.

  24. Kenneth Fritsch said

    There really is not much science content to these emails. What comes across is primarily related to the advocacy stance of the participants. They seem to be nearly to the man (did not see any women involved) of the opinion that their cause is just and that the skeptics are all suspect.

  25. Lynn Clark said

    Good job.

    But I’ll add my two cents worth regarding formatting. (Others have adequately addressed the need for that.) I’ll also add that it is in serious need of some proofreading and taking a run through a spell-checker. There are many, many places where there are obvious spelling errors and broken sentences that don’t make any sense. Like someone else commented, I only made it about half-way through before I just couldn’t take it any more; it pains me to have to say that because I think this article does a good job of placing emails and events in historical context.

  26. Kondealer said

    This is VERY interesting- from above;
    From: Eugene Vaganov evag@xxxxxxxxx.xxx
    To: k.briffa@xxxxxxxxx.xxx
    Subject: from Vaganov
    Date: Thu, 6 Mar 97 14:40:15 +0000 (KRS)
    “The Climatic Research Unit of the University of East Anglia, Norwich, Great Britain is one of the world’s leading research organisation specialising in the study of climate change: climate history, current climates, projected changes and impacts. Dr. K.R.Briffa, Senior Research Associate at the Climatic Research Unit, has considerable experience in climatology and with the use of statistical methods of climate analyses and dendroclimatic reconstruction, especially with regard to large-spatial-scale reconstructions”.

    Yet when I emailed Briffa (Fri 06/11/2009 15:02)
    asking about the validity of the statistical analyses employed in (climate) reconstructions
    This was my reply
    “I do not think that I am qualified to defend all “statistical analyses employed”. There are occasions when I would acknowledge some disagreement with the methods used and in retrospect I myself would have done some things differently or reported results someone differently – but I feel that the vast majority of published analyses provide sufficient details of data and methods (and limitations of both) to provide the reader with a realistic basis for interpreting the outcomes and their associated limitations. Obviously these are sometimes more apparent to an informed reader than one who is not so familiar with the background literature, but this is not a situation that is peculiar to dendroclimatology.”

    So
    a) he does not feel qualified to “defend all methods”- I wonder which he has doubts about?
    b)That he is having second thoughts about both methods and results.

    Personally I think Briffa is one of the better (less bad) guys at CRU. At least he has the decency to reply.

  27. nukemhill said

    Jeff, thanks for fixing the formatting. Much easier to read. I’ll take another read at it now. Seriously, with a little work, this would be an article worth publishing in a major magazine.

  28. John F. Pittman said

    Please note that the section that starts with the following isis from the emails not my work: “”While the report overall is an endorsement of the IPCC report and the process, it has a lot of “buts” in it, and the overall tone is to somewhat downplay the problem. It does not focus on policy relevant issues. The report was done in a very hurried fashion and perhaps as a result, there are several factual errors or misstatements and there are errors of omission. My impression is that it tends to overstate the caveats and need for questioning of results and understate the certainties and likelihoods. 1. In dealing with natural variability, there are two aspects that are mixed in this report….”
    This is a frank discussion with each other about problems with the perception of other scientists. Looking backwards from the perspective of M&M, Wegman, and NAS (North) we can conclude that support of the “hockey stick was misplaced. Also, keep in mind what the real conversation seems to be about. In order to get all those science groups to sign on, the “hockey stick” has to be supported at this time. Though some of the researchers don’t think it should be necessary, it was what was recommended and as we know now, it was done this way.

  29. John F. Pittman said

    The following I wrote: “”Here there is one quote worth mentioning the header has been saved. It is about the divergence problem which at this point has been a minor issue to the “Team”. It become much more:””

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  31. Layman Lurker said

    John Pittman: Here is a post from Von Storch on climate models and paleo reconstructions which I thought you might be interested in.

    http://klimazwiebel.blogspot.com/2009/12/climate-reconstructions-and-future.html

  32. Layman Lurker said

    #31

    Correction: the post was by Eduardo (Zorita?) and not Von Storch.

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