McIntyre calls on PNAS & Michael Mann to issue retraction

Steve McIntyre’s analysis of contaminated data used by Mann et al 2008 demonstrates that relevant criteria for retraction has been met based on PNAS publication policy.

Dirty Laundry II: Contaminated Sediments

From time to time, scientists inadvertently use contaminated data and their results are affected. For example, some time after publication of Grand et al (PNAS 2004), the authors determined that their results were erroneous as a “result of contamination of genomic DNA with plasmid DNA”. They promptly issued a retraction, expressing their regret for the error and any inconvenience. The reputation of the authors does not appear to have been diminished by the retraction. Mistakes happen and the mistake was promptly dealt with by retraction of the article.

Like Grand et al, Mann et al 2008 (M08) used contaminated data, in their case, the Finnish sediment data of Tiljander et al, the modern portion of which had been contaminated by agriculture and bridgebuilding. In addition to using the modern contaminated portion of the data, M08 made a second error by using the Tiljander lightsum and XRD upside down to the interpretation of its originators. Their handling of Tiljander data has been sharply criticized on different occasions by two eminent Finnish paleolimnologists – Atte Korhola here and Matti Saarnisto here.

In contrast to Grand et al, Mann et al have not issued a retraction or corrigendum or even admitted an error. Instead, in multiple venues (without explicitly admitting an error), they’ve asserted that, in any event, the error doesn’t affect their “central conclusions” [their PNAS reply, Feb 2009 here] or, more recently, “any” of their conclusions [Mann et realclimate, June 2011 here], as though that ended the matter.

It doesn’t. Even if the error didn’t have a material impact on the results, a Corrigendum should have been issued. Kaufman et al 2009, for example, issued a corrigendum when they learned that they too had used data (including their Tiljander series) upside down. But the situation for Mann et al 2008 is quite different. The most prominent claim for Mann et al 2008 was its supposed achievement of a “skillful” reconstruction without tree rings for the past 1300 years. Unfortunately, this “achievement” can now be seen to have been a complete mirage, dependent on the use of contaminated data in the EIV reconstruction without tree rings.

In the realclimate response to controversy over the Yamal proxy in September 2009, for example, the EIV no-dendro reconstruction of M08 was put forward as a supposed repudiation of Climate Audit:

Oh. The hockey stick you get when you don’t use tree-rings at all (blue curve)?

It has subsequently become a staple in public defence of the Stick, e.g. Skeptical Science here and here and numerous others. All such assertions rely on the supposed “skill” of the M08 EIV reconstruction. Unfortunately, the “achievement” was an illusion, as Mann et al quietly admitted in the SI to Mann et al 2009.

PNAS Policies on Retraction and SI

PNAS has the following policy on corrections and retractions:

PNAS publishes corrections for errors, made by the journal or authors, of a scientific nature that do not alter the overall basic results or conclusions of a published article. PNAS publishes retractions for major errors that may call into question the source of the data or the validity of the results and conclusions of an article. Errata are published at the discretion of the editors and appear as formal printed and online notices in the journal.

The use of contaminated sediments in M08 was, at a minimum, an “error”. This has been clearly stated by Finnish paleolimnologists Korhola and Saarnisto. Kaufman et al 2008, of which Bradley was a co-author, have already acknowledged a lesser error and issued a corrigendum.

As shown above, despite claims to the contrary, the error has a major impact on the EIV reconstruction without tree-rings and its verification statistics, both of which were relied on in the M08 assertion that they had achieved a “skillful” reconstruction without tree rings for the past 1300 years.

As noted in the lead paragraph, scientists sometimes use contaminated data. If science is to be “self-correcting”, then scientists actually have to issue corrections and, if necessary, retractions. As the example of Grand et al 2004 shows, this actually happens from time to time, but life goes on.

So too here. Mann et al 2008 meets relevant PNAS criteria for retraction. Hopefully, either PNAS or the authors will see the wisdom of retracting the article before it gets used by IPCC AR5.


Full post here: Dirty Laundry II: Contaminated Sediments

For those that wish to bring this to the attention of PNAS edotors, here’s the contacts for PNAS from their website. Please be direct, factual, and courteous if you choose to send a letter.


700 11th Street, NW

Suite 450

Washington, DC 20001

Phone: 1-202-334-2679

Fax: 1-202-334-2739

General Questions:


Web site:

Permission requests: Editor-in-Chief

Randy Schekman


Kenneth R. Fulton

Executive Editor

Diane M. Sullenberger

Feedback form here



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July 6, 2011 10:33 pm

It’s time the global warming community (for want of a better description) started owning up to their mistakes.

Dr Mo
July 6, 2011 10:39 pm

Let the AR 5 use M08. When the error is exposed, as AR 4 errors have been, the damage will be even greater!

July 6, 2011 10:45 pm

Why would Mann apologize? He suing Tim Ball the one honest scientist around, but not backed
by big sponsors. This man must be pulled up for the misinformation he has given, and the Australian government used in the incorrect ‘The Critical Decade’ report that the government
has used as a reason for introducing carbon tax? Mind you they added a disclaimer on pg 2
saying they could not be held responsible for inaccuracies?

Greg, Spokane WA
July 6, 2011 10:49 pm

“Unfortunately, the “achievement” was an illusion, as Mann et al quietly admitted in the SI to Mann et al 2009.”
Is there a link to this, so we can use it when the topic comes up?

July 6, 2011 10:51 pm

“I did not know it would be a hit, Mickey” Fredo in Godfather II

July 6, 2011 11:08 pm

So if we are talking about error correction, whatever happened to the error I found on the surface stations, site in this record
The origin had a picture of the interior of the Stevenson screen showing this was in fact not a working instrument, but merely an unused screen in storage, I contacted Mr watts (or whoever admins the site) and pointed this out, I never received a reply but the very next day the image I refer to had been removed. This was ~2 years ago yet that record remains to this day.

Roger Carr
July 6, 2011 11:12 pm

bushbunny says: (July 6, 2011 at 10:45 pm)
“…Australian government used in the incorrect ‘The Critical Decade’ report that the government has used as a reason for introducing carbon tax? Mind you they added a disclaimer on pg 2 saying they could not be held responsible for inaccuracies?”
If our (Australian) government can “not be held responsible for inaccuracies” then who can? Is it even likely anyone ever will be? Disclaimers like this are being used as a licence to lie… guess they always have been, but it continues to sadden me that such caveats are used by any person over 10 years of age (when there is still time to beat the inclination out of them).
I have a lot of things I would like to claim, if I can be absolutely certain I have the out of a hungry dog and that judge and jury will accept my plea — and perhaps even express sympathy that I was even exposed to any suspicion of bad intent. But I would not try and run a country that way.

Brian H
July 6, 2011 11:15 pm

As suggested by the Climategate emails, Mann is vindictive and dishonest. This leopard is not going to change his spots regardless of any PNAS alterations in policy or institutional bias.
But his papers can and should be rejected for cause.

Martin Brumby
July 6, 2011 11:52 pm

It has been asked before and I’ll ask again.
If the cAGW “science” is so certain, how come it has to be propped up by blatantly obvious dogma, incompetence, greed and malice?

July 7, 2011 12:04 am

For years I thought I was reading the errata from the CAGW community, and I waited patiently for the full papers.
Now you are telling me that they WERE the real papers and there is no errata.
Oh dear

July 7, 2011 12:11 am

@dan typically can’t make a distinction between peer review science publication and web site admin.

John Brookes
July 7, 2011 1:41 am

Oh come one, next you’ll be asking Monckton to issue corrections – and to promise not to do it again!

Bob Ryan
July 7, 2011 3:05 am

The story of global warming science will go down as one of the classic case histories in the philosophy of science. There is a view that has been expressed on this blog and elsewhere that science progresses through the development of theories which survive until some refuting evidence is found that brings them down. That ‘Popperian’ view of science is highly influential among scientists and is taught as the key methodological principal on scientific research degree courses.
But Popper was not the last word on the matter and the undermining of Mann’s results by McIntyre and others is the latest in a long line of studies and commentaries which bit by bit are undermining the AGW research programme. Lakatos, for example gives a very coherent account of how scientific programmes progress and how they degenerate (see for a good discussion of Lakatos’s contribution). It is clear that there is a core of scientists who are highly committed to the core of their research programme. They have resolutely defended it, as Lakatos cogently describes in Lakatos and Musgrave ed. (1970). Criticism and the Growth of Knowledge. Cambridge: Cambridge University Press, by the development of ad-hoc modifications and arguments in a way which Popper would have said was quite inadmissible and led to pseudo-science.
The big question is where is climate science now? After a decade of solid critical work the AGW research programme is not as pristine as it once was. What I am sure will happen is that more and more studies will arise, based upon empirical observation, which undermine the primacy of core concept that CO2 is the global climate regulator and in this respect McIntyre’s critique is invaluable. No one, by themselves, will provide the ‘killer blow’ but gradually the guardians of the core of the programme will lose their influence and become increasingly marginal to the development of climate science. I can understand why the leading proponents of AGW seek to defend the core of their research programme to the bitter end but they will be judged not by what they defend but by their willingness to listen to their critics and to change.

July 7, 2011 3:17 am

Its good that they don`t clean up thier own mess!
It shows clearly the standards of the AGW “science”. Thugs dressed up as scientists protected by the activists politicans and the UN..They know they can get away with anything and they are.

July 7, 2011 4:15 am

Lol Dan, best you can moan about is a photo, brilliant, you do realise there where thousands and i’m sure a stats guy could give you the odds on there being one or two errors.
What you must ask yourself is does the error help the author in anyway? do you think Anthonys grant depended on it?

July 7, 2011 4:58 am

John Brookes says, July 7, 2011 at 1:41 am

“Oh come one, next you’ll be asking Monckton to issue corrections – and to promise not to do it again!”

I know you have a great dislike of Chris Monckton, John, but I think you should acknowledge two things about the man and the way he works:
1. When he makes a mistake, he is man enough to admit to it, apologise for it and ensure the people concerned know that (I have seen him do this on video and read his retractions nad apologies in print).
2. Chris Monckton is NOT responsible for policy-making documents that, in the hands of politicians are going to drain the world’s economies of trillions of dollars.
All we ask of those who are building these policies, is that they show competence, but not complacency; rigour, but not dogma; and, maybe, just a litlle humility in what they are doing – and planning to do to their fellow man – and not hubris. It also helps not to have a closed mind on the subject, as it seems, from my reading of the many negative posts you continually make around the world, you seem to have.

John Brookes
July 7, 2011 5:30 am

Is the following relevant, or am I missing something?
Reply to McIntyre and McKitrick: Proxy-based temperature reconstructions are robust
McIntyre and McKitrick (1) raise no valid issues regarding our paper. We specifically discussed divergence of ‘‘composite plus scale’’ (CPS) and ‘‘error-in-variables’’ (EIV) reconstruc- tions before A.D. 1000 [ref. 2 and supporting information (SI) therein] and demonstrated (in the SI) that the EIV reconstruction is the more reliable where they diverge. The method of uncertainty estimation (use of calibration/validation residuals) is conventional (3, 4) and was described explicitly in ref. 2 (also in ref. 5), and Matlab code is available at http://www.meteo.􏰀mann/supplements/MultiproxyMeans07/code/ codeveri/calc_error.m.
McIntyre and McKitrick’s claim that the common procedure (6) of screening proxy data (used in some of our recon- structions) generates ‘‘hockey sticks’’ is unsupported in peer- reviewed literature and reflects an unfamiliarity with the concept of screening regression/validation.
As clearly explained in ref. 2, proxies incorporating instrumental information were eliminated for validation and thus did not enter into skill assessment.
The claim that ‘‘upside down’’ data were used is bizarre. Multivariate regression methods are insensitive to the sign of predictors. Screening, when used, employed one-sided tests
only when a definite sign could be a priori reasoned on physical grounds. Potential nonclimatic influences on the Tiljander and other proxies were discussed in the SI, which showed that none of our central conclusions relied on their use.
Finally, McIntyre and McKitrick misrepresent both the National Research Council report and the issues in that report that we claimed to address (see abstract in ref. 2). They ignore subsequent findings (4) concerning ‘‘strip bark’’ records and fail to note that we required significance of both reduction of error and coefficient of efficiency statistics relative to a standard red noise hypothesis to define a skillful reconstruction. In summary, their criticisms have no merit.
Michael E. Mann1, Raymond S. Bradley, and Malcolm K. Hughes Pennsylvania State University, Walker Building, University Park, PA 16802
1. McIntyre S, McKitrick R (2009) Proxy inconsistency and other problems in millennial paleoclimate reconstructions. Proc Natl Acad Sci USA 106:E10.
2. MannME,etal.(2008)Proxy-basedreconstructionsofhemisphericandglobalsurface temperature variations over the past two millennia. Proc Natl Acad Sci USA 105:13252– 13257.
3. Luterbacher J, Dietrich D, Xoplaki E, Grosjean M, Wanner H (2004) European seasonal and annual temperature variability, trends, and extremes since 1500. Science 303:1499 –1503.
4. Wahl ER, Ammann CM (2007) Robustness of the Mann, Bradley, Hughes reconstruction of surface temperatures: Examination of criticisms based on the nature and processing of proxy climate evidence. Clim Change 85:33– 69.
5. Mann ME, Rutherford S, Wahl E, Ammann C (2007) Robustness of proxy-based climate field reconstruction methods. J Geophys Res 112:D12109.
6. Osborn TJ, Briffa KR (2006) The spatial extent of 20th-century warmth in the context of the past 1200 years. Science 311:841– 844.
Author contributions: M.E.M., R.S.B., and M.K.H. wrote the paper. The authors declare no conflict of interest. 1To whom correspondence should be addressed. E-mail: © 2009 by The National Academy of Sciences of the USA

Scottish Sceptic
July 7, 2011 6:05 am

Bob Ryan says: July 7, 2011 at 3:05 am
The story of global warming science will go down as one of the classic case histories in the philosophy of science.
Totally agree!
But, I don’t think the conclusion will be “global warming science got it wrong”. I think the conclusion will be much bigger: “20th century ‘science’ was corrupted by its own success into believing that the science “brand” endowed omnipotence.
The reason I think the problem is much wider than climate “science” is because when presented by the evidence, far from chastising this “rogue” subject, the scientific elite merely closed ranks as if they simply couldn’t see what they had done wrong. Perhaps it was saving the “goose that laid the golden egg” … not willing to undermine this flagship area which had brought “science” so much prestige. Realistically, I think it is just like the corruption of the Catholic church in the renaissance: where the the elite gained so much from the machinery of their organisation that they lost sight of the real justification, philosophy and ethos that created the necessary foundation on which their organisations were originally built.
Perhaps the best way to describe this demise is that science is no longer a subsidery tool of our industrialised society, but now it is very much a secular religion. “Science” is not a tool to be used if and only if it is useful, now science all powerful all persuasive: it is something to be “followed”, something to give “moral guidance”, something that tries to force others to accept its viewpoint.

John Whitman
July 7, 2011 6:09 am

Bob Ryan says:
July 7, 2011 at 3:05 am
“The story of global warming science will go down as one of the classic case histories in the philosophy of science. . . .”
– – – –
Bob Ryan,
Excellent write up on the scientific method versus the problematic IPCC focused climate science. Thanks.
I would add a caution about Popper and Kuhn wrt their ideas that have contributed to the views of some current scientists on the scientific method. My impression is they put undue emphasis on limited parts of an entire process that is the broader view of the scientific method; their main focus was somewhat myopic. I think their minimizing of the broader process was unfortunate for the broader view of the scientific process.

July 7, 2011 6:18 am

Bob Ryan @ 3:05 AM: Thanks for the very thoughtful comment. I checked out the Wiki entry on Lakatos (of whom, to my shame, I had never heard: I am still stuck on Popper in my ongoing auto-didactic program) and it’s great stuff. As for your thesis that McIntyre and other critics are providing impacts that will cumulate toward a “break,” when the (C)AGW programme is discarded as degenerate, I hope you’re right. I worry that the impulses will not cumulate but dissipate into heat; that they will die or wander in the contested space between science and politics. Blogs like WUTW are in the very center of that contested space; like hill-forts in prehistoric times, they allow scientists to take and hold strategic ground. Without them, the barbarians’ rule will only prosper.

July 7, 2011 6:24 am

John Brookes says:
July 7, 2011 at 1:41 am

Oh come one, next you’ll be asking Monckton to issue corrections – and to promise not to do it again!

Can you give us the citation for a peer-reviewed paper Monckton has published that has need of correcting?

Vince Causey
July 7, 2011 6:46 am

John Brookes says:
July 7, 2011 at 1:41 am
“Oh come one, next you’ll be asking Monckton to issue corrections – and to promise not to do it again!”
When bereft of arguments, invent a straw man and attack that 🙂

July 7, 2011 6:47 am

John Brookes says, July 7, 2011 at 5:30 am:

“Is the following relevant, or am I missing something?
Reply to McIntyre and McKitrick: Proxy-based temperature reconstructions are robust…etc”

John, I’ve just come off CA reading the original blog post from Steve. I also read ALL the comments, including many from your alter-ego, Nick Stokes. I wonder why I didn’t find this fulsome comment of yours over there as well. Could it be the Steve M might just deal with you as thoroughly – and, I have to say, courteously and respectfully – as Nick Stokes?
Go on, grow a couple and cut ‘n’ paste your comment to CA. I love a good read.

July 7, 2011 7:01 am

John Brookes says:
July 7, 2011 at 5:30 am
Is the following relevant, or am I missing something?
Probably missing something. In regards specifically to the screening method chosen creating hockey sticks, I seem to remember McIntyre specifically doing work that showed using randomized data and screening it in the same way Mann did had a bias for creating hockey sticks. Was it peer reviewed? I don’t know that it was, but it was certainly demonstrated for all to see, and I don’t remember anyone with knowledge of statistics being able to pick it apart.
The claim that M&M don’t understand regression screening/validation was laughable. Mann, a climate scientist, is claiming that world-class, published statisticians don’t understand basic principles around filtering data for regression analysis.
On multiple occasions M&M has demonstrated flawed statistical applications on the part of Mann and Company. Sometimes they show a significant error, sometimes the show not much error. Either way, the team usually refuses to acknowledge the errors, make corrections and then move on. It’s not that hard.

July 7, 2011 7:04 am

John Brookes,
the letter you note is relevant and very wrong. It is a good example of how they protect garbage and will not admit any error. You should drop by CA and ask Steve himself for the details of what is wrong with it. Of course, you will probably be politely instructed to search his site for the relevant posts where it was dissected.
Just a small amount of research would have saved you the embarassment of presenting this in public showing your gullibility.

ferd berple
July 7, 2011 7:46 am

For some reason Climate Science ignores “reproducible” as a criteria for acceptance.
Imagine if the same standard was applied to other sciences. All that would be required would be a peer reviewed paper claiming that “cold fusion” worked and billions would be earmarked to be spent on “cold fusion” to replace fossil fuel and solve AGW. This would be great if you were a researcher or manufacturer of “cold fusion” related products, but a potential disaster for everyone else.
While there is some evidence that “cold fusion” does work, to date it has not been consistently reproducible, thus any major investment in “cold fusion” would have a high risk of being a very bad investment. It could be that “cold fusion” sometimes appears to work for reasons similar to why a stopped clock sometimes appears to have the correct time. Chance.
We see a similar result in Climate Science. For example, the climate models are sometimes right, sometimes wrong. When the are right, Climate Science points to this as proof that Climate Science is right. When the climate models are wrong, Climate Science points to excuses such as aerosols and volcanoes. Chinese pollution and the Mt Pinatubo bounce. None of which are foreseen in advance. This suggests Chance is at work, not science.
The normal practice in science is that if results cannot be independently reproduced, they are not science. The failure of climate models and the IPCC to predict the leveling off of temperatures post 1998 should have caused both Climate Science and the IPCC to suspend belief in AGW. That would have been normal scientific practice. Instead they changed the focus from Global Warming to Climate Change, and pointed to the unpredicted change post 1998 as further proof that climate is changing.

Jeff Alberts
July 7, 2011 7:48 am

Dan says:
July 6, 2011 at 11:08 pm
Did Anthony’s paper depend almost entirely on that one photo or temp site? I seriously doubt it. Mann’s work, however, depends entirely on a couple carefully selected and manipulated data sets, which get heavily weighted during the analysis. Without those, he can’t get a stick.

Steve McIntyre
July 7, 2011 8:25 am

re John brookes:
the Mann et al 2009 Reply is highly relevant to the post. That’s why I quoted from it and linked to it. In a way, the entire post is directed at the assertion in their 2009 Reply that the error did not affect their “central conclusions”. Just because they made this assertion doesn’t make it true. If you care to read my post, you’ll see that I’ve examined information and data that have been subsequently been conceded, showing that the contaminated data has a dramatic impact on their EIV reconstruction without tree rings, that they’ve admitted this and that the central conclusion of M08 – that they had achieved a skillful reconstruction without tree rings for 1300 years – does not hold up once the error is taken into consideration. So yes, the Reply is relevant, but its claims (and not just on this point) are untrue.

July 7, 2011 1:54 pm

This issue is discussed in Supplemental Information for PNAS Article “Proxy-Based Reconstructions of Hemispheric and Global Surface Temperature Variations over the Past Two Millennia” at
Inclusion or exclusion of these proxies makes very little difference read, none to the conclusions of the paper, and only a tiny difference to the reconstruction graph – although excluding them actually shows a cooler Medieval Warm Period, see for details.
Steve McIntyre – I honestly don’t think you have a case, here. If one or two proxies are problematic, it’s not going to strongly bias a reconstruction made with >1200 proxies. You’re trying to make a mountain out of a molehill.

Steve McIntyre
July 7, 2011 2:38 pm

You may think so, but they do. The M08 method is quite quirky. Remember the “rain in Spain” being mislocated in Kenya. To my surprise, correcting that simple geographical error resulted in changes of up to 0.5 deg C in Sh reconstruction (see Oct 2008 filings at Mann’s website.) So don’t assume that the impact of 4 Tiljander proxies is going to be negligible.
In particular, the main “achievement” of M09 was their claim to a reconstruction ‘without tree rings”. This reconstruction does not use 1209 proxies. Te earlier portions (pre-1500) have many fewer proxies – you’re quickly down to 20 or so no-dendro proxies. Mann has already admitted that, withotu the Tiljander data, he no longer has a “skillful” no-dendro reconstruction back for 1300 years (now only 500 years). This in itself is a big impact. If you look at the recolored nodendro EIV reconstruction without the Tiljander data, you can see for yourself (on Mann’s own calculations) that there is a substantial impact. It’s not just me saying it. It’s all on the record.
What you have to watch is precisely what Mann (or Schmidt) say. They commonly answer a different question than the one that was asked. Unless you are familiar with the details, you won’t notice the sleight of hand.

July 7, 2011 3:17 pm

Steve McIntyre – To clarify my previous post: you are complaining in this page about the Tiljander et al results being included in Mann 2008. You show yourself (, Left – Effect of contaminated data on the with-bristle (all-proxy) EIV reconstruction; right – on CPS no-dendro reconstruction) that removing the Tijander data has very very little effect on the results. Only removing all dendro proxies altogether significantly changes the graph, which is not relevant to your “contaminated data” claim. You’re complaining about contaminated data, but arguing it with a different subset altogether!
Either way, the Mann 2008 conclusions of:
“We find that the hemispheric-scale warmth of the past decade for the NH is likely anomalous in the context of not just the past 1,000 years, as suggested in previous work, but longer. This conclusion appears to hold for at least the past 1,300 years (consistent with the recent assessment by ref. 2) from reconstructions that do not use tree-ring proxies, and are therefore not subject to the associated additional caveats. This conclusion can be extended back to at least the past 1,700 years if tree-ring data are used, but with the additional strong caveats noted.”
are certainly not modified by the inclusion or exclusion of the Tijander data.

John M
July 7, 2011 3:51 pm

The problem is that the hockey stick is only retained with statistical significance if one questionable proxy (Tiljander) is replaced with another (Bristlecones).
Odd isn’t it, that a “robust” set of 1200 proxies only show a hockey stick if one or the other of these proxies is used?

July 7, 2011 4:14 pm

The excellent post by Steve McIntyre (SM) is well worth a read in full. When those who doubt the need for a retraction should consider this. A scientific paper should establish a thesis. It should same something. As SM makes reference, the thesis of Mann et al 2008 was that It is possible to make a proxy temperature reconstruction without both tree ring proxies, and without a medieval warm period (MWP). This, by any measure, has failed. Yet again we have a multi-proxy reconstruction that relies for its thesis upon flawed reconstructions. Search Climate Audit for Graybill, Gaspe, Yamal and Tiljander and you will see why. Or save the research by reading Monford’s “The Hockey Stick Illusion”.
The continued campaign to establish the absence of a MWP always falls over by the weakest data. There are two conclusions that are now open. Either, the older, established conclusion, that temperature increases like those in the 20th century warming are nothing exceptional, or to say that there is insufficiently strong evidence to establish the temperature trends before regular temperature readings.

Steve McIntyre
July 7, 2011 5:48 pm

I made no reference to the Medieval Warm Period in my post.
KR, the following statement of Mann et al 2008 is now known to be false when contaminated is not used:

This conclusion appears to hold for at least the past 1,300 years (consistent with the recent assessment by ref. 2) from reconstructions that do not use tree-ring proxies, and are therefore not subject to the associated additional caveats.

That was the point of my post. Your repeating the false statement doesn’t make it true.

July 7, 2011 7:19 pm

I have often wondered if the easiest way to end Mann’s obsession with the MWP is to invite him on a archeological dig to one of the northern Norse settlements in Greenland and ask him to exhume one of the buried settlers using tools of the period. Do you think when he hits the permafrost a couple of feet down, a light may come on? Probably not, but the video of him whaling away on the permafrost would be priceless.

July 7, 2011 7:46 pm

I’m a bit lost here. My argument has always surrounded the opinion, our planet is an ice planet
and we have experienced an interglacial for the last 12,000 years depending on what part of the
globe we are studying. Some places in the Northern Hemisphere were uninhabitable until 10,000
years ago, but not Australia that sustained an Aboriginal population for at least 45,000 years.
800AD – 1300s AD this was the medieval warm period for Europe, and then the mini ice age
came to pass. Then we hear of the Roman warm period. The wine industry in UK took a tumble, but the wine presses were turned into printing presses eventually. Since 1850 or so the globe warmed up. With a few years here and there when it was cold and we are cooling again. So who would be most effected eh? The Northern hemisphere should it get any colder. Now they are suggesting putting giant fans under the gulf stream that is slowing to keep it moving? Or the thought that it has stopped because ofthe huge Gulf oil spill? I maybe not a scientist but I have a degree in Archaeology and Palaeoanthropology and studied human evolution and adaptation. And modern day humans where able to survive in parts of the middle east and Southern Europe
during the last ice age too. But when I heard Al Gore etc., start his nonsense and won the Academy award and then Nobel prize with the IPCC I said straight away. This is incorrect, if anything we should expect the planet to cool. If you study the last 150 years, yes the planet has warmed thank goodness, but not as much as during the medieval warm period. Now we hear it hasn’t warmed since 1998. I am sure Steve will agree, that data can be corrupted to suit the
hypothesis, and we have certainly proof of this.
The main argument or lie is that humans are creating this extreme warming phase. Yes humans
pollute for sure, but CO2 is not to blame and carbon dioxide should not be taxed. With Minister
Combet at Cancun committing $600 million a year to the UN Climate Change fund to be distributed to poorer countries who are suffering because of climate change caused by developed
countries screams of corruption and the Green dream of redistribution of wealth. And Mann
Jones, Gore, the UN IPCC are part of this and have been paid billions to prove AGW by manipulating data or fabrication of such by the governments who want to deprive the populations
of funds. Something must stop them. Mann has now admitted the planet has not warmed since 1998 and can’t explain why. Can’t someone in some scientific authority explain to them why?
Strongly and with the backing of other notable scientists.

July 7, 2011 8:07 pm

Oldgamer56: Some time ago, the Queen of Denmark stated, that Greenland was once occupied
by pastoral folk, then the environment became to hard (cold) to survive. The burial sites seem to indicate those who stayed on lost their former robust physical appearance and the skeletal evidence showed signs of possible starvation or lack of protein consumption. I am sure there
are reports on these findings.

July 7, 2011 8:24 pm

Well, Steve, Mann properly qualified his statements about the longer reconstructions. And the Tijander data makes very little difference in the shorter reconstruction. Which one are you actually concerned about?
The data which you consider contaminated makes no difference to the conclusions. And you have not presented a case against the dendro data. Mixing arguments does not reinforce your case.

July 7, 2011 9:13 pm

@Scottish Sceptic
I very much enjoyed your disquisitions on how science proceeds, Bob Ryan, and followed the link you provided to Imre Lakatos, which I read with great interest. I had come across his name while studying the history of science, but actually paid more attention to his friend, the philospher of science Paul Feyerabend, and did not realize how closely the two were linked.
Feyerabend’s ideas resonate with yours, Scottish Sceptic. He published a paper that helped propel me into my field, titled ‘How to Defend Society Against Science’ which made the arguments that you make here, but in a far more provocative manner:
“According to Feyerabend, new theories came to be accepted not because of their accord with scientific method, but because their supporters made use of any trick – rational, rhetorical or ribald – in order to advance their cause. Without a fixed ideology, or the introduction of religious tendencies, the only approach which does not inhibit progress (using whichever definition one sees fit) is “anything goes”: “‘anything goes’ is not a ‘principle’ I hold… but the terrified exclamation of a rationalist who takes a closer look at history.” (Feyerabend, 1975).”
The Wikipedia article is quite good:

Steve McIntyre
July 7, 2011 9:36 pm

KR, without the contaminated data, as I said on many occasions, their central conclusion to have achieved a skilful reconstruction without tree rings for the past 1300 years is bogus. These claims were not qualified. They need to be retracted.

Pete H
July 7, 2011 11:03 pm

KR says:
July 7, 2011 at 8:24 pm
” The data which you consider contaminated makes no difference to the conclusions. And you have not presented a case against the dendro data.”
Steve has not presented the evidence! You truly need to keep up and improve your memory!
John Brookes? You are way out of your league! Strawman attacks now! Back to the Antipodean blog with you!

Bob Ryan
July 8, 2011 1:29 am

A side note on the positions of Lakatos and Feyerabend and their relevance to the current debate. Both were excellent scholars and along with Thomas Kuhn held Popper in very high regard. Lakatos and Feyerabend strongly opposed one another on many issues and it is said that when they had a dispute Feyerabend would nail his response to the wall behind Lakatos’s favourite armchair in the senior common room at the London School of Economics. The point is, however, that although they often disagreed with one another (and vehemently so) they still had a deep respect for one another’s position and they continued to argue and debate up until Lakatos’s untimely death. They both knew that through listening to and where necessary accepting criticism knowledge and understanding grows. Feyerabend was devastated at his friend’s sudden death – intellectual giants in any field do not need to be arrogant. You know them by their willingness to engage in debate, their openness to friend and critic alike and fundamentally by their humility. Where would climate science be now if its leading proponents were giants?

John Brookes
July 8, 2011 4:35 am

So maybe Steve McIntyre has a point. But (of course) this does not have any relevance to AGW. I suspect that if this wasn’t a proxy battle over AGW, there would be less heat in the debate, and conciliation might be easier.

July 8, 2011 7:15 am

Listen John Brookes and KR, it’ll by eons before you prove Steve McIntyre’s analysis wrong as he has one quality you both don’t have. That is expert statistical knowledge, integrity, honesty, truth and a specific disposition to stick to facts and back what he says with evidence. All you have bee showing here is a constantly shifting put, without substance.

July 8, 2011 7:44 am

John Brookes – I have to agree with your comment. The majority of arguments regarding Mann and similar works do seem driven by the proxy battle over AGW, not the scientific quality of individual papers. If this kind of criticism was aimed at all scientific works, we would still be in the Stone Age.

July 8, 2011 3:43 pm

If this kind of criticism was NOT aimed at all scientific works, we would indeed still be in the Stone Age.

John M
July 8, 2011 3:44 pm

Claiming this is just a proxy fight over AGW is like claiming Piltdown Man was just a proxy fight over ev0luti0n.

July 8, 2011 7:39 pm

Bob Ryan on 7 Jul 3.05 am. Bob that is so right. But the ALP and Greens coalition are about
to introduce a carbon tax this coming Sunday, even though the ABC stated that the EU carbon
emissions trading scheme is worthless and is a good excuse for banks and investors to make money plus the scams. The EU parliament has just voted out any agreement to increase carbon
emissions. In fact they have increased in some countries. So Australia is quite out of touch with the rest of the world doesn’t it? Well if I know all this bunkum about so called climate change
science, how is they don’t know? Which leads me to believe that this has a political agenda
of the worst kind. One world government Brown wishes, and redistribution of wealth at the
Australian people’s expense. How can we stop this madness eh? $210 for each pensioner?
What a cheek! $4 a week?

July 9, 2011 3:19 pm

KR, John Brookes,
“This kind of criticism” is mathematically correct and exposes the fallacies of a scientist who holds to his preconceived conclusions no matter what the evidence says. That’s the kind of criticism that enables science to move forward.
And yes, it goes to the heart of the AGW question, because the question is all about “is today’s climate unusual?” — which is what Mann et al purport to answer in the affirmative. Whether they are right or wrong is exceedingly important.

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