You can always tell a Mann, but you can’t tell him much – why tree ring data (and climatic conclusions from it) sucks

From the “we only select wood for hockey stick construction” department.


Steve McIntyre comes back into the fray with a scathing review of just how crappy the tree ring proxies used by Michael Mann were (and still are), and shows without the questionable stripbark portion of the data, why no “hockey stick” appears. But even worse, McIntyre illustrates that Mann, the hockey team, and the paleoclimate community haven’t learned one damn thing with the release of the latest set of tree ring data.

From Climate Audit:

The PAGES (2017) North American network consists entirely of tree rings. Climate Audit readers will recall the unique role of North American stripbark bristlecone chronologies in Mann et al 1998 and Mann et al 2008 (and in the majority of IPCC multiproxy reconstructions).  In today’s post, I’ll parse the PAGES2K North American tree ring networks in both PAGES (2013) and PAGES (2017) from two aspects:

  • even though PAGES (2013) was held out as the product of superb quality control, more than 80% of the North American tree ring proxies of PAGES (2013) were rejected in 2017, replaced by an almost exactly equal number of tree ring series, the majority of which date back to the early 1990s and which would have been available not just to PAGES (2013), but Mann et al 2008 and even Mann et al 1998;
  • the one constant in these large networks are the stripbark bristlecone/foxtail chronologies criticized at Climate Audit since its inception. All 20(!) stripbark chronologies isolated by Mann’s CENSORED directory re-appear not only in Mann et al (2008), but in PAGES (2013). In effect, the paleoclimate community, in apparent solidarity with Mann, ostentatiously flouted the 2006 NAS Panel recommendation to “avoid” stripbark chronologies in temperature reconstructions. In both PAGES (2013) and PAGES (2017), despite ferocious data mining, just as in Mann et al 1998, there is no Hockey Stick shape without the series in Mann’s CENSORED directory.

PAGES2K references: PAGES (2013) 2013 article and PAGES (2017) url; (Supplementary Information).

Background: Stripbark Bristlecones and Mann’s CENSORED Directory

In our 2005 articles, Ross and I pointed out that the Mann’s hockey stick is merely an alter ego for Graybill’s stripbark bristlecone chronologies and that the contribution from all other proxies was nothing more than whitish noise. We noted that Graybill himself had attributed the marked increase in late 19th and 20th century bristlecone growth to CO2 fertilization, not temperature – a theory which was arguably a harbinger of the massive and widespread world greening, especially in dry areas, over the 30 years since Graybill et al (1985).

In a CA blogpost here, I further illustrated the unique contribution of bristlecones by segregating the additive contribution to the MBH98 reconstruction of bristlecones (red) and other proxy classes (e.g. ice cores, non-bristlecone North American tree rings, South American proxies, etc. in blue, green, yellow ). This clearly showed that (1) the distinctive MBH98 Hockey Stick shape arose entirely from bristlecones and that (2) all other proxy classes contributed nothing more than whitish noise – with their combined contribution diminishing in accordance with the Central Limit Theorem of statistics.

Mann had, of course, done a principal components analysis of his North American tree ring network without stripbark bristlecones – an analysis not reported in his articles, but which could be established through reverse engineering of his now notorious CENSORED directory – see CA post here. ) These non-descript PCs further illustrate the non-HSness of the Mann et al 1998 North American tree ring network without strip bark bristlecones.

Figure 2. Plot of five principal components in MBH98 CENSORED directory i.e. without Graybill stripbark chronologies, mainly from bristlecones, but a couple of limber pines. 

The 2006 NAS panel stated that stripbark chronologies (i.e. the Graybill bristlecone chronologies) should be “avoided” in temperature reconstructions. Although Mann et al 2008 stated that it was compliant with NAS recommendations, Mann flouted this most essential recommendation by including all 20 stripbark series isolated from the CENSORED analysis.

Because of persistent criticism over the impact of these flawed proxies, Mann et al (2008) made the grandiose assertion that he could get a hockey stick without tree rings (and thus, a fortiori, without stripbark bristlecones) – a claim credulously promoted by Gavin Schmidt at Real Climate. However, it was almost immediately pointed out at Climate Audit (here) that Mann’s non-bristlecone hockey stick critically depended on a Finnish lake sediment “proxy”, the modern portion of which (its blade) had been contaminated by modern agriculture and road construction and which had been used upside-down to its interpretation as a temperature proxy in pre-modern times. Mann was aware of the contamination of lake sediments, but argued that his use of contaminated (and upside down) data was legitimate because he could get a HS without them  – in a calculation which used stripbark bristlecones. When challenged to show results without either stripbark bristlecones or upside-down mud, Mann (and Gavin Schmidt) stuck their fingers in their ears, with the larger climate community obtusely refusing to understand a criticism that was obvious to any analyst not subservient to the cause.

In the weeks prior to Climategate, I used increasingly harsher terms for the addiction of the paleoclimate community to the data-snooped stripbark chronologies, describing them as “heroin for paleoclimatologists”, with Briffa’s spurious Yamal chronology as “cocaine” (e.g. herehere), occasioning much pearl-clutching within the hockey stick “community”.


  • ex post screening based on recent proxy trends necessarily biases the resulting data towards a Hockey Stick shape – a criticism made over and over here and at other “ske;ptic” blogs, but not understood by Michael (“I am not a statistician”) Mann and the IPCC paleoclimate “community”;
  • the PAGES 2017 North American tree ring network has been severely screened ex post from a much larger candidate population: over the years, approximately 983 different North American tree ring chronologies have been used in MBH98, Mann et al 2008, PAGES 2013 or PAGES 2017. I.e. only ~15% of the underlying population was selected ex post – a procedure which, even with random data, would impart Hockey Stick-ness to any resulting composite
  • despite this severe ex post screening (in both PAGES 2013 and PAGES 2017), the composite of all data other than stripbark bristlecones had no noticeable Hockey Stick-ness and does not resemble a temperature proxy.
  • PAGES 2013 and PAGES 2017 perpetuate the use of Graybill stripbark chronologies – despite the recommendation of the 2006 NAS Panel that these problematic series be “avoided” in future reconstructions. PAGES 2013 (like Mann et al 2008) used all 20(!) stripbark chronologies, the effect of which had been analysed in Mann’s CENSORED directory. PAGES 2017 continued the use of the most HS stripbark chronologies (Sheep Mt etc) both in the original Graybill version and in a more recent composite (Salzer et al 2014), while adding two stripbark chronologies used in Esper et al 2002 and other IPCC multiproxy studies.

In the past, I charged Mannian paleoclimatologists as being addicted to Graybill stripbark bristlecone chronologies – which I labeled as “heroin for paleoclimatologists” (also describing Briffa’s former Yamal chronology as “cocaine for paleoclimatologists”. Unfortunately, rather than confronting their addiction, Gavin Schmidt and others responded with haughty pearl-clutching indignation, while, behind the scenes, the PAGES consortium doubled down by perpetuating use of these problematic proxies into PAGES 2013 and PAGES 2017.

On this day in 2009, (Oct24) a few weeks before Climategate, I suggested appropriate theme music by Eric Clapton and Velvet Underground. Still apt nine years later.


In the first comment at Climate Audit, Willis sums up the Mannian mendaciousness very well:

Well, it seems to me that you could have saved yourself lots of work by just reposting your objections to the original Mann HS paper, which are the same objections to every succeeding Mann-alike since then … it’s deja vu all over again.

I gotta say, I am totally gobsmacked. Near as I can tell, they’ve got a perfect record—every error, every wrong process, every data-mining method, every after-the-fact proxy selection, every piece of bad data, every bogus stripbark pine record, they have have all simply been moved from one study, to the next, to the next, without the slightest sign that they have learned from, or even noticed, their egregious errors …

Can’t say enough for your patience in all of this, wading endlessly through the murky waters only to find the same bovine waste material as you found last time.

Gotta say, if I were doing it, I certainly wouldn’t have been as … well … Canadian … in my description of these double-dealing lying malfeasant pseudo-scientists.

Grrrr …

As always, the world owes you immense thanks for your tireless work in revealing this unending deception time after time.

Well done, that man!


Don’t forget, there’s always this book:


Review here, and available on Amazon here.

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October 25, 2018 6:04 am

trouble with paleo….if you use enough samples to make it legit

…you will always end up with a flat line

Mark - Helsinki
October 25, 2018 6:24 am

Good read.

Hayhoe is another staunch defender of this bad science, a pathological liar akin to Mann and Schmidt. That little community has done more damage to the reputation of science than any other pseudo science cadre in history. The damage to NASA’s reputation is done, sorry but it is, it is a political entity, mind you, sending up a known junk shuttle cos muh funding, killing astronauts, also didn’t help, and the junk science astronomy (WMAP for one) at NASA is also a massive stain.

The corruption of science, not only climate science, is a sign of a return to the dark ages, where morals and politics override scientific results.

We are at a point now where a “science historian” can claim “there is no difference between the biological sexes” on TV and not be challenged because it’s a leftist view.

Science, the institution needs to be purged, seriously.

There needs to be a large international effort to assess and discard the TONS of junk science in the mainstream. We are going backwards. The more enlightened we think we are, the closer we get to another dark age.

Taylor Pohlman
Reply to  Mark - Helsinki
October 25, 2018 6:42 am

If we’re entering a new ‘Dark Age’, at least this time we’ll know who turned out the lights…

Reply to  Mark - Helsinki
October 25, 2018 7:35 am

“Professing themselves to be wise they became fools”

Harry Passfield
Reply to  Mark - Helsinki
October 25, 2018 10:37 am

Mark, It’s not just damage to the reputation of science, it’s the knock-on effect as politicians jump on a bubble that will make them rich and/or allow them to control their electorate.

Jon Salmi
Reply to  Mark - Helsinki
October 25, 2018 10:59 am

Fascism has crept in under the velvet glove of political correctness. The velvet glove has now come off. Whether you are talking about politics, science, sports, every day work relationships or whatever, every word you say is scrutinized and if you are found to be out of (goose) step you will be hounded until you confess your anti-fascist sins. Fortunately, it appears the revolution is beginning to eat its own. Bon appetit!

Allan MacRae
Reply to  Jon Salmi
November 8, 2018 4:34 am

Thank you Jon – good comment.

We have entered an era where deceit and conformity are rewarded and honesty and integrity are punished.

All that is required for evil to triumph is for good men to do nothing.

Alan Tomalty
Reply to  Mark - Helsinki
October 25, 2018 8:31 pm

[snip -wildly off topic- mod]

Shawn Marshall
Reply to  Alan Tomalty
October 26, 2018 5:48 am

Good comment. As just an engineer I always wondered why I could not ‘get’ relativity.

Cyril Wentzel
Reply to  Alan Tomalty
October 26, 2018 3:01 pm

You might find David Harriman’s analysis interesting since it connects the current path of physics to philosophical thoughts that have undermined the human cognition for several decades.
I suggest you listen to his taped lectures such as the intriguingly titled “The Philosophical Corruption of Physics” and “Physicists lost in Space” and more. Also, of course, his book “The Logical Leap”, exploring in a positive way how valid concept formation and integration is the key to building valid knowledge. And also convincingly demonstrate how having the wrong epistemological practice will lead you to blind alleys.

October 25, 2018 6:32 am

Have Mann and company ever dealt meaningfully with Steve’s observations? Do they have plausible sounding excuses for what they’re doing? If they ignore the criticism and just bull along as if nothing happened does their conduct become criminal negligence?

dodgy geezer
Reply to  commieBob
October 25, 2018 6:45 am


Occasionally one of their pals writes a rebuttal paper, which carefully avoids addressing any of the real points and translates them into strawmen interpretations which are easy to disprove.

Then Steve’s paper can be ignored because it has been ‘rebutted’.

Kristi Silber
Reply to  commieBob
October 27, 2018 11:45 pm


They have responded, both in the literature and out of it. It’s not so much a matter of “excuses” for what they did, but pointing out flaws in what McIntyre and McKitrick did. As far as I know, Mann never really owned up to his statistical error, though others have shown that it did not significantly affect the results. Also as far as I know, the inclusion of bristlecone pines did not make or break the analysis.

I know you and plenty of others will disagree with me, but from all I’ve read on the subject, it seems to me that McIntyre and McKitrick had so many flaws in their own analyses that it’s hard to find anything they say as credible. That’s my honest opinion, and I really have tried to be dispassionate in my assessment and look at a range of sources, including their own papers and posts. (I’m not a fan of Mann at all!) But I’m no statistician, and all I have to go on is others’ evaluations. This is one post that also seems to try to be fair:

I frankly don’t understand the colorful graphs shown. There has been so much work on climate reconstruction, it seems extremely unlikely that all these proxies contributed nothing but white noise. Why would they be used at all? There’s something fishy about this. I don’t trust people who are he11-bent on discrediting others, as they have been from the beginning. And they just never stop! The papers they discuss are from 10 and 20 years ago. Give it a rest, already.

Can’t you see he wants to belabor this for a reason? Can’t you see the way he wants to stir up emotions?

You might be interested in this:

Or you could read more recent research by Mann and colleagues that addresses the use of tree rings,

Or you could read the NAS 2006 report

…No, their conduct does not become “criminal negligence”! This is SCIENCE. It is expected that there are errors in science. Scientists are human. They also have egos, some bigger than others. Personally, I think Mann was young and pumped up by the attention and allowed his ego to get in the way of his professionalism in handling the controversy. Hopefully he has learned from the experience, and from Climategate. It can’t be fun getting your personal emails exposed, or getting death threats as a result.

Allan MacRae
Reply to  Kristi Silber
November 8, 2018 4:43 am

Hello Kristi,

I have followed the MBH98 debacle since its publication. It was obviously false the very day it was published, because it eliminated from the historical record both the Medieval Warm Period and the Little Ice Age.

We are indebted to Steve McIntyre for his remarkable skill and diligence in dissecting the false data and mathematics of the Mann hockey stick.

It is clear now, after the publication of the Climategate emails, that the hockey stick was not only false, it was fraudulent.

dodgy geezer
October 25, 2018 6:34 am

…But even worse, McIntyre illustrates that Mann, the hockey team, and the paleoclimate community haven’t learned one damn thing with the release of the latest set of tree ring data….

On the contrary!

They have learned that it doesn’t matter if the raw data, the processing and the conclusions drawn are ALL dodgy. The key thing is to keep producing papers which say that it’s worse than we thought.

That way, the politicians can always say that the latest paper supports the need to put more taxes on…..

Joe Crawford
Reply to  dodgy geezer
October 25, 2018 7:43 am

+10 :<)

Reply to  dodgy geezer
October 25, 2018 3:47 pm

The number of papers contributes the the Consensus.

October 25, 2018 6:45 am

How Mann, or the rest of his reviewers, ever thought the Hockey Stick was valid considerring historic proxies for temperature escapes me. Sure, the LIA was inconvenient for the “CO2 is the temperature control knob” theme, but MBH98 was over the top.

Joe - non climate scientist
Reply to  Tom Halla
October 25, 2018 7:17 am

Even more astonishing is the claim that the elevated MWP temps was confined to north western europe, the north atlantic and the NE coast of canada.

Could it be that it was because there was actual contemporanous written record of the warmer temps.

Kinda implausible that there was an extreme weather event sitting over the same small portion of the globe for 300+ years – but apparently all the climate scientists believe it so.

AGW is not Science
Reply to  Joe - non climate scientist
October 25, 2018 9:25 am

Never mind those trees that used to grow higher on the mountainsides THEN than they do NOW, nothing to see here!

Reply to  Tom Halla
October 25, 2018 7:38 am

I have my doubts that any of them ever thought the Hockey Stick was valid. It was useful, and that was much more important.

Komrade Kuma
Reply to  MarkW
October 25, 2018 8:05 am

Spot on methinks. It was always about providing ‘plausible deniability’ of being utter junk. McKintyre uses various strong drugs as metaphor’s for the paleocrap diet of drivel implicit in Mann’s ‘work’and that perhaps bells the cat. LSD was developed to assist CIA interrogations where the altered reality inside the brain would lead to a subject opening up with their secrets. In the CAGW case it is that old shaman’s favourite drug , fear, that is administered and people just switch off their instinct for skepticism.

How to make a human behave like a sheep? Scare the crap out of him/her.

AGW is not Science
Reply to  MarkW
October 25, 2018 9:39 am

Oh but I think they DO – these are AGW True Believers, after all – their arrogance knows no bounds. Confirmation Bias is strong in this group – they accept ONLY the information that appears to support their pre-conceived conclusions.

I seem to remember Mann saying something recently about how proxies older than [fill in the blank] years before present were not trustworthy/valid/whatever. In other words, CONVENIENTLY dismissing all that INCONVENIENT paleoclimate record that shows NO relationship between CO2 and temperature WHATSOEVER, and shows significant episodes of REVERSE correlation which would be impossible if CO2 were the great “climate driver” they claim it to be today.

So excluding all the information they don’t like would appear to be routine amongst this cabal of pseudo-scientists, and they seem quite content that they do so rightfully. It’s a secular religion at this point, no amount of contrary information would dissuade them.

Reply to  AGW is not Science
October 26, 2018 4:24 am

Why would you use data that disproves your thesis? The data is obviously wrong if it contradicts your idea. That’s the wonder and the beauty of having so much crappy data. You can throw out the crappy data that disagrees with you, and keep the crappy data that agrees with you.

Kristi Silber
Reply to  AGW is not Science
October 27, 2018 11:53 pm

AGW is not Science

“Confirmation Bias is strong in this group – they accept ONLY the information that appears to support their pre-conceived conclusions.”

Why is it that McIntyre and McKitrick’s work, which has been widely criticized, is taken as truth by skeptics while the many reconstructions since Mann et al. supporting their work are dismissed? Even the NAS 2008 panel cited in the post supports these reconstructions. Is this not a classic case of confirmation bias on the part of skeptics?

Reply to  Kristi Silber
November 2, 2018 2:20 am

Kristi, try talking to a statistician or a geologist about that data and its uses.

And I would point out that McIntyre and McKitrick’s work had to be reverse engineered as Mann et al refused to release the data and their model. That in itself tells you everything because a real scientist would release the data and the model for testing. That is what science used to be. I suggest you read a Disgrace to the Profession where even climate scientists who believe in AGW tell you why Mann et al are truly non scientific and appalling.

October 25, 2018 6:57 am

“Graybill himself had attributed the marked increase in late 19th and 20th century bristlecone growth to CO2 fertilization”

OF course, cold, dry, stressed. Co2 is a life line.

The hockey stick IS valid, it maps the increase in CO2 over the last 1000 years, perfectly.

Gordon Dressler
Reply to  MattS
October 26, 2018 8:36 pm

Exactly. It is unbelievable (well, maybe not) that Michael Mann makes the same basic mistake, intentionally or not, that so very many people make when they look at a graph of variable “y” plotted against variable “x”. There seems to be a tendency to presume the graph means that “y” must be related to x because the two are plotted together, never considering that spurious correlations or third parameters might be involved.

Of course, as the saying goes, “correlation does not equal causation”. Most simply in this case: if “x” causes an increase in “z”, and “z” in turn causes and increase in “y” it is not scientifically correct to say that variations in “y” are caused by variations in “x”.

I believe it was Roy Spencer in his book “The Great Global Warming Blunder” that had the example of a curve that could be created to show that shark attacks had a strong correlation to ice cream sales. It was not that ice cream consumption caused shark attacks but rather that warm summer weather brought more people to the beach, thereby increasing ice cream sales, and at the same time increasing the frequency at which people entered the water where hungry sharks abide.

October 25, 2018 7:00 am

I applaud Willis’ above compliment to Steve McIntyre:

“Can’t say enough for your patience in all of this, wading endlessly through the murky waters only to find the same bovine waste material as you found last time.

Gotta say, if I were doing it, I certainly wouldn’t have been as … well … Canadian … in my description of these double-dealing lying malfeasant pseudo-scientists.

Grrrr …

As always, the world owes you immense thanks for your tireless work in revealing this unending deception time after time.

Well done, that man!”

I guess I’m not as “Canadian” as Steve M – I called fraud on MBH98 etc and the entire hokey team long ago, because they eliminated the Medieval Warm Period and the Little Ice Age from the historic record, and that was false.

But Steve M actually took the time to decipher the Byzantine factual errors and dissect the mathematical falsehoods endemic to the MBH98 nonsense. Steve’s work took remarkable talent and diligence, and must be applauded.

AGW is not Science
October 25, 2018 9:42 am

Indeed. And I think in large part that’s what the “Climate Team” counts on – that those who are pointing out the weakness of their bullshit are going to simply run out of energy or time or money so that the bullshit will come to be accepted as “fact.”

October 25, 2018 7:05 am

I’m no statistician, but I understand that even random numbers put into Mann’s model will generate the “Hockey Stick”.
Even baseball scores?

The Deplorable Vlad the Impaler
Reply to  Bob Hoye
October 25, 2018 8:30 am

A friendly word of caution to you, Mr. Hoye:

Lest you incite the anger and malefisence of one of the (several) Kristi Silber’s here, I would stay away from telling any of her that ‘noise’ , or anything else, fed into the HS algorithm, produces the hokey schtick shape. While one of her tells you that trees are not valid paleotemperature proxies, another one will tell you (at the same time) that McIntyre and McKittrick (sp?) “forgot” to remove the hokey-schtick signal in the algorithm.

I may be out of the loop here, but it was always my understanding that a computer program produced what the programmer wanted.

Have I missed something?

Reply to  The Deplorable Vlad the Impaler
October 25, 2018 6:17 pm

Vlad, Vlad, Vlad, you’re so deplorable!

Kristi Silber
Reply to  The Deplorable Vlad the Impaler
October 28, 2018 11:39 am


“While one of her tells you that trees are not valid paleotemperature proxies”

I never said that, as I made clear. Are you intentionally misunderstanding me or lying or is your comprehension really that bad? You are certainly lying about there being more than one of me.

Please don’t speak for me.

Reply to  Bob Hoye
October 25, 2018 6:17 pm

Not random numbers, but a specific type of data called “red noise”.

Kristi Silber
Reply to  Bob Hoye
October 28, 2018 11:50 am

Bob Hoye,
“I understand that even random numbers put into Mann’s model will generate the ‘Hockey Stick’.”

The assertion you are talking about has been debated:
“What is claimed is that McIntyre & McKitrick produced their red-noise by using the data from Mann, Bradley & Hughes, but forgot to de-trend, or remove the underlying hockey stick shape. Therefore, the reason their [McIntyre & McKitrick’s] analysis produced hockey sticks was not because the Mann, Bradley & Hughes analysis was flawed, but because there was a hockey stick profile in their data.”

It’s not so much that the hockey stick will always appear in M&M’s (flawed) analysis, but that it’s much more likely to appear.
…and following comments

(And don’t listen to Vlad’s comments about me. Why should I be mad? It’s not my research.)

October 25, 2018 7:07 am

With so little data to back up his claim, Mann could simply estimate the tree ring data from the discarded samples!

Ron Long
October 25, 2018 7:11 am

Good post, Anthony and Steve. Looks like Reality has once again bitten Professor Mann in his (Moderator: don’t SNIP me, bro! Please substitute the current politically correct phrase for “fat ass”, like maybe “ample gluteus maximus” and finish the post, thanks).

October 25, 2018 7:21 am

Well, this is easy enough to understand, just arrest everyone in the NH where there is winter as a future criminal. After all 97% will be using fossil fuel to keep warm.
I was wondering, I cut down a large spruce in 2000 that was planted in the 1940’s. In looking at the tree rings, you could clearly see the larger width of tree rings when it was wetter and cooler. I looked at the width of the tree ring from 1988, when it was very hot and dry, very small. I was curious so I looked at other trees that were cut at that time, and the same pattern emerged. So does that contradict Mann’s findings?… I can hear the replay, ‘ where’s your link ? ‘.

Reply to  rishrac
October 25, 2018 11:06 am

When looking at trees in isolation, the width of the rings will give you a very good idea of how much rain fell during Spring and summer that year.
And not much else.

michael hart
October 25, 2018 7:29 am

While McIntyre may focus on the various statistical offences of the Strip Barking crew, I am yet to be persuaded that the discipline has any scientific merit at all.

The many idiosyncratic variables in the growth of a tree depend on water, temperature, location, nutrition (including CO2!), …and more besides. I have never seen that these are reliably linear or quantified sufficiently for construction of good calibration curves. The degrees of freedom alone indicates that the subject is a joke.

They select a subset trees that follow a correlation maybe for a short time, with no evidence that it holds well over either time, or changes in the other variables. And that is about where they get down to where McIntyre starts criticizing them. It still takes my breath away that this is considered acceptable science by people who really should know better.

Steve O
Reply to  michael hart
October 25, 2018 8:02 am

Year ago I read an English translation of an extract of a paper put out by Chinese science organization similar to our National Institute of Science. They conducted a ring study of trees on the Tibetan plain and predicted that warming may have peaked and that we may be entering a 40 year cooling period.

I’ve now lost all trace of that study and can’t even find any references to it.

Roy Martin
Reply to  Steve O
October 25, 2018 8:31 am

This one?

Liu Y, Cai Q F, Song H M, et al. Amplitudes, rates, periodicities and causes of temperature variations in the past 2485 years and future trends over the central-eastern Tibetan Plateau. Chinese Sci Bull, 2011, 56: 29862994, doi: 10.1007/s11434-011-4713-7 [ Climate Change over the Past Millennium in China.]

Link to study times out.

Found reference to it here (with Hat Tip: Geoffrey Gold):

Maurice Lavigne
Reply to  michael hart
October 25, 2018 10:20 am

Micheal, I agree with you. One additional variable is the growth stage. I live in a jackpine stand, it is my garden. This stand like most, sprouted after a fire in the early sixties. I have felled more than 100 all of which show that the growth rate during the first 15 years is 3 times faster, based on ring thickness. Jackpines do this because in the early years they are tightly packed and only the fastest growing trees survive as they block sunlight for the others. Over 50 years the density will go from 5000 trees per acre to several hunderd looming over the dead ones. Hubris is the definitive study of this UN ruse and I recommend frequently to my photosynthesis denier acquaintances.

Dave Fair
Reply to  michael hart
October 25, 2018 10:53 am

Shut Up, they argued.

October 25, 2018 7:36 am

Tree rings chronical growing conditions during the growing season. Nothing else. Temperature is a component of growing conditions, just one of many. Teasing out temperature from all the other things that affect growing conditions is impossible.
Tree rings tell you nothing about what is happening outside the growing season.

Beyond each tree has an ideal temperature for growth, when temperatures get above or below that point, growth slows (all other things being equal). So even if were possible to tease out the temperature component, you couldn’t tell if a increase in growth was being caused by the temperature being above the ideal point and cooling, or being below the ideal point and warming.

October 25, 2018 7:43 am

Unfortunately, here in the UK, politicians (even those not on the various gravy trains), would sooner whine and hand-wring about fuel poverty, devastated public services, etc, all caused by “Austerity” whilst checking out Lonely Planet’s latest worldwide fly-to holiday destinations than actually ask some basic questions. You couldn’t make it up.

October 25, 2018 7:49 am

Mann trained as a physicist. What does he know about plant morphology and sedimentation geology? Clearly not enough to question the capacity of his data for recording temperatures.

Reply to  Gary
October 25, 2018 6:22 pm

“McIntyre trained as a statistician. What does he know about plant morphology and sedimentation geology?”

See how specious such an argument is? Facts don’t care about qualifications.

Dave Fair
Reply to  Jeff Alberts
October 25, 2018 6:53 pm

And the facts are against Mann.

Reply to  Dave Fair
October 27, 2018 8:27 am

“And the facts are against Mann.”

Indeed they are. I was simply pointing out that going after someone’s qualifications doesn’t automatically mean you can ignore what they say.

Kristi Silber
Reply to  Jeff Alberts
October 27, 2018 10:01 pm

Jeff Alberts,

Actually, he didn’t train as a statistician, although he has a Bachelor’s in mathematics. He then got an interdisciplinary degree in politics, philosophy and economics.

Kristi Silber
Reply to  Gary
October 27, 2018 10:11 pm


Mann got both his Master’s and PhD in geology and geophysics.

Dendroclimatology isn’t dependent on knowing plant morphology as a whole. There is no reason to “question the capacity of his data for recording temperatures” – the pertinent question is how to assemble and analyze them well.

Gerald Machnee
October 25, 2018 7:58 am

Has Unreal Climate responded yet? i have not gone there yet for my comedy fix.

M Courtney
Reply to  Gerald Machnee
October 25, 2018 11:54 am

That website is dead.
It was founded to communicate climate science to the layman. But as climate “scientists” refuse to debate they were unable to answer even the basic questions every educated layman asked.
So they let the website die by starvation. It had become too embarrassing.

michael hart
Reply to  M Courtney
October 25, 2018 3:47 pm

I quickly abandoned reading there, after witnessing the unbridled arrogance of the Gavin himself.

Years afterwards I read here that Saint Ferdinand of Englebeen, possibly the most patient man I have met on the internet, gave up on them for unreasonable censorship. When they show no respect to the mildest of critics, then they have shown the world the contempt they have for all of us. I now just feel embarrassed that Gavin Schmidt speaks with a similar accent to me.

Ian Wilson
October 25, 2018 8:24 am

Imagine if someone said to you that: “Many tree-ring chronologies are not good temperature proxies, therefore most, if not all, tree-ring proxies are useless for determining regional or global temperatures changes over centennial time scales.” How would you react?

If you believe in the scientific principle and the use of logic to investigate nature, your reaction should be that this is total BS. Why you ask.

Because it is a blanket statement that can be shown to be incorrect by the use of observational evidence and simple logic. There are regional tree-ring chronologies that have been shown to match:

a) modern-day instrumental temperature records over the last 100 to 150 years.
b) temperature proxies that are not based on tree-ring chronologies e.g Strontium isotopes ratios in sea corals.

This, while it may be true that we should be wary of using tree-ring chronologies as temperature proxies, it is not true that we should reject this technique outright.

Please note: This is not an attack on anyone. It is simply a summary of my beliefs on this whole topic.

Curious George
Reply to  Ian Wilson
October 25, 2018 8:44 am

If you have a sufficient number of divergent proxies, you can always pick ones that support your theory – excuse me, belief. This has nothing to do with science. It is pure politics.

The Deplorable Vlad the Impaler
Reply to  Ian Wilson
October 25, 2018 8:55 am

Hoping you have a good day, Mr. Wilson, I would add this:

It is not a simple matter of, “this does NOT work”, or “this works really well”; it is a matter than any claimed method needs to undergo a period of calibration and testing, BEFORE we can make any substantive conclusion on it (and, ergo, the validity of the method). Dr. Urey and his team did not just suddenly “invent” the delta-Oxygen-18 paleothermometer; the first thing they did was cross-check it, create some calibration curves, find what potential errors could or did creep into the analysis, THEN they published their hypothesis for the entire community of related disciplines to verify.

Good ol’ Mikey and The Bandits took something, and ran with it, without first bothering to do any kind of testing of the method, and establishing it as a valid proxy. Our resident ‘ecologist’ even stated directly to me (single word answer when I asked if tree rings are a valid temperature proxy: “No.”, back on a 30 April 2018 thread) that a tree ring is not suitable for this purpose.

Of course, the same individual then comes back and vigorously defends the hokey-schtick, claiming that PCA, ‘ … took care of … ‘ the problematic parts. As McIntyre points out again, Mikey et al used a sedimentological series UPSIDE-DOWN, due to the fact that had they used it ‘right-side-up’, it would have contradicted their “findings”.

I have no problem with someone finding, creating, using a method, but until it has been tested, refined, confirmed through numerous cross-checks and cross-calibrations (which one would think most scientists, including ecologists, should know is necessary), the hokey-schtick is, at best, an interesting idea.

But please do not take it as accurate.



D. J. Hawkins
Reply to  Ian Wilson
October 25, 2018 10:05 am

The problem is that there is no proxy that is good across all time even locally. Sooner or later they drift away. That means that they are good for their calibrated range and no more. That puts paid to using them as proxies for a deeper dive, time-wise.

Reply to  Ian Wilson
October 25, 2018 10:54 am

Anything is theoretically possible. However finding a grove of trees that have everything they need to prosper except it’s too cold is sufficiently difficult that assuming it to be impossible is not ridiculous.
Beyond that, even if you COULD prove that this grove of trees is temperature limited now, proving that it has always been so is once again an excercise in futility.

Beyond that, you still have to deal with the problem that tree only grow during the growing season so tree rings give you no information for that portion of the year where trees aren’t growing, so declaring that you can use them as proxies for whole year temperatures is even more ridiculous.

Ian Wilson
Reply to  MarkW
October 26, 2018 7:04 am

– There are tree-species that have been growing near the tree-lines on the side of Rocky mountains adjacent to the nearby Pacific oceans for hundreds, if not thousands of years. We have records of the tree-lines in the Rockies moving up and down the sides of these coastal mountains over recorded history. The movement of the tree-line is in response to the slow long-term warming and cooling of the nearby North Pacific Ocean. Direct observations show that the width of the tree rings in these tree-species vary with the mean sea-surface temperatures of the North Pacific ocean when these widths are averaged over inter-annual to centennial time-scales.

Nearly 100 of years of Pacific Ocean sea-surface temperature measurements show that the regional temperatures in the North-East Pacific Ocean anti-correlate with regional sea-surface temperatures of the Southern Tropical Pacific Ocean near Tahiti. If you look at the corals that surround these islands, you can use Strontium isotopes in the corals to determine the sea-surface temperatures over at least 400 years. What you find is that long-term decadal to centennial changes in sea-surface temperatures (measured using Strontium isotope ratios) that surround the islands near Tahiti are very strongly anti-correlated with the tree-ring proxy temperatures measured from the trees that grow near the tree-line on the side of the coastal Rocky Mountain ranges. This is is exactly what you would expect if the broad patterns in Pacific Ocean sea-surface temperatures measured in the instrument period (i.e the last 100 years) could be projected back a further 300 years.

Chris Hanley
Reply to  Ian Wilson
October 25, 2018 1:52 pm

Selecting or screening random proxy samples on the basis of chance correlation with the 20th century instrumental record is assuming that those samples are good ‘thermometers’ and others are not which is ridiculous, it’s circular reasoning.

October 25, 2018 8:38 am

Such revelations are all well and good for thinking people who understand what is being said, but I fear that the people who need to understand how wrong this stuff is cannot comprehend why, because they do not have the background to grasp the sophistic mastery of pseudoscience. Even I don’t totally get it, but I do get the between-the-lines-of-technical-analysis-jargon indications that bad statistics WAS, indeed done.

How do we simplify this analysis for people (i.e., politicians, activists, etc.) who need to accept how wrong the methods are ?

Reply to  Robert Kernodle
October 25, 2018 8:48 am

Okay, I clicked on the review of that book, and I guess this quote from that review might serve to answer my earlier question:

““So his [Mann’s] hypothesis that it [the temperature record] looks like a hockey stick is confirmed only because a tree ring that produces a hockey-stick shape is given 390 times the weight of a tree ring that does not.” (Steyn, 5)”

Reply to  Robert Kernodle
October 26, 2018 4:19 am

Why would you choose to use data that disproves your discovery?

October 25, 2018 8:45 am

By now anyone still believing Dr. Mann has serious brain problems, since the evidence against him is OVERWHELMING!

John Endicott
Reply to  Sunsettommy
October 25, 2018 11:34 am

Always remember: It is difficult to get a man to understand something, when his salary depends on his not understanding it

Greg Woods
October 25, 2018 9:12 am

As they say – you can lead a Mann to science, but you can’t make it think….

AGW is not Science
October 25, 2018 9:15 am

I don’t know what’s worse – his continual cherry-picking and recycling of the same bullshit “proxies” (because they tell the story he likes) or the scientific incompetence of grafting the garbage “reconstruction” together with instrument readings. Makes me sick just to look at his ugly mug with that permanent smirk on it.

E J Zuiderwijk
October 25, 2018 9:18 am

Perhaps these are rings you are looking for:

October 25, 2018 9:29 am

“Sophisticated” statistical algorithms can only be applied to data that have sophisticated understanding, otherwise its garbage in, god knows what out, or sometimes what comes out is anything you desire.

AGW is not Science
Reply to  climanrecon
October 25, 2018 9:56 am

As I like to put it, computers are very stupid – they do EXACTLY what you tell them to do. No more, no less.

D. J. Hawkins
Reply to  AGW is not Science
October 25, 2018 10:07 am

Yes, computers will truly be useful when they do what we want them to do, not what we tell them to do.

October 25, 2018 12:10 pm

>>attributed the marked increase in late 19th and 20th century
>>bristlecone growth to CO2 fertilization, not temperature.

The reverse is also true.

Last Glacial Maximum (LGM) temperatures were derived by tropical treelines, which were assumed to be regulated by temperature. But this made for very cold tropical temperatures at altitude, and impossibly high lapse rates to match them. And these figures were then used by modern climate models to calculate CO2 sensitivity.

In truth the LGM treelines were modulated by low CO2 concentrations, not low temperatures. This means that all the LGM upper air temperatures, lapse-rates and sensitivities are wrong…


Kurt in Switzerland
Reply to  ralfellis
October 25, 2018 3:22 pm


Do you have a reference to a paper looking at LGM temperatures and treelines (latitude and/or elevation) and the lapse rate calculations (e.g., versus modern day agreed-upon constants)?

October 25, 2018 9:19 pm

This seems appropriate:

October 26, 2018 12:33 am

Just bought a Sherwood hockey stick and the rings are getting smaller . Global cooling is underway . Take it to the bank . The only way to save humanity and polar bears is to burn fossil fuels as rapidly as possible .
Any questions ? Oh yes I own shares in most fossil fuel companies but my interests are purely for saving the planet . Oh yeah and by the way my dog ate my hockey stick so you know… just trust me . I have been studying
Sherwood hockey stick rings for a long time but I sure wish they would bump up the $ subsidies in my pseudoscience industry . I couldn’t make it in real science and university pay sucks without government hand outs . All I need is a pump and dump salesman to sell this crap .

October 26, 2018 6:39 am

Here’s a question: Has McIntyre or any of his followers ever built a climate reconstruction from scratch? They seem to endlessly pick apart the reconstructions made by others, but I don’t know whether they have actually taken all their good advice and used it to make a reconstruction the “right way.” If Mann is so wrong, why not show him how to do it right?

Robert Stewart
Reply to  AlJo1816
October 26, 2018 9:41 am

Their ‘good advice’ is simply that Mann’s approach is neither logically sound, nor impartially implemented. This is hardly a prescription for the development of a “climate model”, although one would hope climate modelers would incorporate such considerations as necessary, but not sufficient, elements of any subsequent effort. It may well be the case that we do not have nearly enough data to discover useful ‘climate models”. Our understanding of climate on a world-wide scale with fairly fine resolution dates back to the development of satellite in the 1960s, and our record of the world from those sources is thus only 50 years in duration, spanning just a handful of solar cycles, and a similar number of large scale eruptions of volcanoes. At the same time, we know that the atmosphere is “chaotic”, in the sense of Lorenz, which means we cannot compute the evolution of atmospheric motions even with the highly detailed information we can derive from satellites. Existing “climate models” are nothing but a shot in the dark, that presume we can ignore what we know about the physics of the atmosphere. It would be nice if they worked, but they don’t. It may be politically inconvenient to recognize this reality, but it is the truth. It would be foolish in the extreme to accept these “models” simply because those who point out the failures of these efforts do not have an alternative. To ignore the critics and embrace these discredited models basically require a religious commitment, which is only too obvious when you examine the supporters of Mann, et al.

The Deplorable Vlad the Impaler
Reply to  AlJo1816
October 26, 2018 11:19 am

Greetings, and hope for a great day for you, Aljo1816:

Posts on this thread are getting thin, so if you are still watching, please allow me to see if I can respectfully comment on your post.

First, as we all know, neither McIntyre nor McKittrick (sp?) are what we would call “scientists” in the same vein that Mann, Schmidt, Tim Ball, David Middleton (frequent contributor here) etc are. Working from obscure memory, one is (I think) and economist, and one is a statistician.

Second, the scientific community, as an aggregate, has deciphered a great deal of information about past climates, on virtually all time scales. We have, for example, established that the later NeoProterozoic (with carbon dioxide concentrations measured in percents [yes, up and down, but percents none the less]) had quite genial climates (e.g., the Ediacaran and Tonian), with times and epochs of extensive glaciation (e.g., Cryogenian). Even with some error bars attached, it is difficult for the current crop of “warmists” (or full-fledged believers in [catastrophic] anthropogenic climate change or [fill-in current meme here]), to account for this discrepancy, since the same factor cannot cause the opposite effect, at different times. That is, if carbon dioxide, in percents of concentrations, was responsible for ‘warm’ episodes, it cannot also be the culprit in causing a glacial pulse of any duration; if it is this “all-powerful” super “greenhouse” gas, there should NOT have been any time that we can discern, for lack of a better term, “cold” or “glacial” conditions.

But it is not in dispute within the geological community that there was a definite, extensive [both temporally and geographically] Late NeoProterozoic glaciation. It is the position of the “skeptic” community, which includes this author, that carbon dioxide is, at best, a very minor player, if it is even a player at all, in the determination of global climate. Numerous other factors are far more powerful, and overwhelm, at all time scales, anything the carbon dioxide might do, or might be capable of doing.

Third, it is axiomatic that as we move forward in time, our resolution of events improves. If we fast-forward from the PreCambrian to the Pleistocene/Holocene transition, we enter into the Holocene Epoch itself. As we approach present-day, there began to exist instrumental temperature records; just a few at first, then more, then more, then … … … until we have satellites (and ground-based and balloon-based records) keeping track of “global” temperature every second of every day, with everyone and his [favorite pet] watching all these data like a hawk.

Between the incipient Holocene, and the beginnings of the rudimentary instrumental temperature records, we have developed methods for estimating past temperatures, including, but not limited to, stalagtites and -mites, written historical records (anecdotes), shore terraces [I grew up around the Lake Bonneville shore terraces, and there’s quite a story to be told from them!), ice cores (Greenland and Antarctica), et cetera … Taking, correlating, cross-checking, quantifying, calibrating, and refining the various methods has produced a reasonable picture of what is likely to have transpired before we had any “hard” data to interpret. There have been, quite literally, thousands of cross-discipline investigators who have pieced all of this together, including those in the sciences themselves, and others who specialize in History, Geography, Agriculture, Linguists, … to name a few.

So here we are: we have what certainly appears to be a decent idea of how “climate” was in the past, before we could directly “measure” it. Insofar as we can tell, things like the Minoan Warm Period, the Roman Warm Period, the Medieval Warm Period, the Little Ice Age, were all real, and were all largely global in scope.

Fourth, M & M could certainly do their own reconstruction; it would be akin to re-inventing the wheel. Somehow, you’re expecting them to come up with something different? or new? or … … … what, exactly?

It is sufficiently-well established that climate has always changed. A changing climate is the norm. There does not exist something that we might call, ‘climate stasis’. It is a myth. Earth climate is a coupled, non-linear, dynamic system, that operates without stationarity*.

And this is where the beef w/ the ‘hokey schtick’ comes in: Mikey and his comrades claimed that they had found that climate changed very little, if at all, for some substantial periods of time (say, nominally, thousands of years) by using these ‘tree-ring’ thermometers. Mikey tried to tell us, who know better, that things like the Minoan and/or Roman and/or Medieval warm periods ( and the consensus view, based on available evidence, is that these time periods were warmer than today) NEVER EVEN HAPPENED! Worse, Mikey, et al, took exceedingly great pains to conceal their “methodology”, the implication being that they KNEW, a priori, that their ‘method(s) was(were) complete garbage. What emerged from the painstaking and roadblocked-at-every-maneuver investigation by M & M were these inconvenient facts: one tree, now known to come from the Yamal pennisula, was given a weighting factor of about 390 times any other “sample”, because it showed exactly what Mikey et al wanted, which is their “signal” of increasing temperatures, co-incident to the Industrial Revolution; the computer algorithm IS a hockey-stick producing program, or in layman terms, it is pre-ordained to show exactly what the programmer wanted. Unless I am mistaken, it would seem to me that most programmers tell their computer to do what they want it to do; somehow I thought that was the aim of “programming”.

As an undergrad, we had lab exercises that involved some basic dendrochonology. We were given unretouched (and live-scale) photographs of some tree rings, and had to deduce a ‘checklist’ of items. We were not told where the trees came from, what time span they represented (other than we had some “old” tree section, a “middle” tree section, and a “young” tree section; one of the goals was to determine from our cross-correlation and analysis, the two extrema and the median section, so there was some absolute overlap in the three time periods represented). It was quite interesting to see periods of abundance, and of stress, and at least one of our “victims” had survived a forest fire. I remember our team struggling to find the overlap; at one point, all those dark/light areas started to blur together, but eventually, we put together a rough chronology from our analysis. We did pass that exercise, by the way.

Fifth, Mikey does not want to know any “proper” way to do a reconstruction. There’s way too much money to be made from shouting “Fire!” in the crowded theatre. Yes, I am accusing Mikey, and just about every other charlatan involved in this whole hoax, of being mercenary. Instead of trying to make a living by doing some genuinely useful research, and solving real problems, the CAGW or CACC alarmists are doing exactly what H. L. Mencken predicted: keeping the populace alarmed with an endless series of hobgoblins, all of the imaginary. They do it solely for profit, and not progress.

So, I hope you enjoyed my dissertation. There is a big problem here on WUWT: if you ask a question, someone just might answer it, so unless you DON’T want an answer, don’t post. I welcome your comments, and will do my best to respond in a timely manner.

My regards to you and yours,


*In my undergrad and grad Geophysics classes, we had to use an ad hoc definition, different from the common definition, widely used in the Statistical sciences. This definition formed the basis for the Math employed in the investigation of Earth phenomena. As restrictive as it is, I see a definite application of the same definition to the climate/meteorological sciences. If it is an incorrect application, then I shall consider myself to stand corrected.

Geoff Sherrington
Reply to  AlJo1816
October 26, 2018 8:31 pm

Look at the graphs above, delete the red bristlecone lines and you have nothing but featureless data on which to try to build a whole new model. Why try?
Steve has answered your question with data, usually a good way to answer

Geoff Sherrington
Reply to  Geoff Sherrington
October 26, 2018 8:36 pm

That was for Aljo1816.

October 26, 2018 11:18 am

You can always tell a Mann, but you can’t tell him much

You can lead a Mann to real data, but you can’t make him use it properly.

Dr Francis Manns
October 26, 2018 1:43 pm

You should see the hockey sticks produced by Professor Lonnie Thompson at Ohio State. H has used Ice core from equatorial glaciers and his are NHL worthy. No Medieval warming and no Little Ice Age, just an alarming hook at the end. He never suspects that firn conditions on a glacier are open and shifting for years, the light oxygen leaving, and calibrating from the current temperature back. It has been published over and over.

Tony Price
October 26, 2018 3:29 pm

“You can lead a Mann to water, but you can’t make him think”.

Kristi Silber
October 27, 2018 9:53 pm

“the one constant in these large networks are the stripbark bristlecone/foxtail chronologies criticized at Climate Audit since its inception. All 20(!) stripbark chronologies isolated by Mann’s CENSORED directory re-appear not only in Mann et al (2008), but in PAGES (2013). In effect, the paleoclimate community, in apparent solidarity with Mann, ostentatiously flouted the 2006 NAS Panel recommendation to “avoid” stripbark chronologies in temperature reconstructions.”

How was it known that these were strip-bark samples? Were they denoted as such? Strip-bark is a condition of the pines in old age, not a species, and it is these in particular that the NAS panel recommended avoiding.

If McIntyre is going to take the recommendations of the NAS panel as trustworthy, it seems he should also take their conclusions as trustworthy.

“It can be said with a high level of confidence that global mean surface temperature was higher during the last few decades of the 20th century than during any comparable period during the preceding four centuries. This statement is justified by the consistency of the evidence from a wide variety of geographically diverse proxies.

“Less confidence can be placed in large-scale surface temperature reconstructions for the period from A.D. 900 to 1600. Presently available proxy evidence indicates that temperatures at many, but not all, individual locations were higher during the past 25 years than during any period of comparable length since A.D. 900. The uncertainties associated with reconstructing hemispheric mean or global mean temperatures from these data increase substantially backward in time through this period and are not yet fully quantified.

“Very little confidence can be assigned to statements concerning the hemispheric mean or global mean surface temperature prior to about A.D. 900 because of sparse data coverage and because the uncertainties associated with proxy data and the methods used to analyze and combine them are larger than during more recent time periods.Despite these limitations, the committee finds that efforts to reconstruct temperature histories for broad geographic regions using multiproxy methods are an important contribution to climate research and that these large-scale surface temperature reconstructions contain meaningful climatic signals. The individual proxy series used to create these reconstructions generally exhibit strong correlations with local environmental conditions, and in most cases there is a physical, chemical, or physiological reason why the proxy reflects local temperature variations. Our confidence in the results of these reconstructions becomes stronger when multiple independent lines of evidence point to the same general result, as in the case of the Little Ice Age cooling and the 20th century warming.

“The basic conclusion of Mann et al. (1998, 1999) was that the late 20th century warmth in the Northern Hemisphere was unprecedented during at least the last 1,000 years. This conclusion has subsequently been supported by an array of evidence that includes both additional large-scale surface temperature reconstructions and pronounced changes in a variety of local proxy indicators, such as melting on ice caps and the retreat of glaciers around the world, which in many cases appear to be unprecedented during at least the last 2,000 years. Not all individual proxy records indicate that the recent warmth is unprecedented, although a larger fraction of geographically”

…It should be noted that Mann et al. were cognizant of the uncertainty of earlier periods, reflected in the title of their 1999 paper, “Northern Hemisphere temperatures during the past millennium: inferences, uncertainties, and limitations.”

Reply to  Kristi Silber
October 28, 2018 4:07 am
Kristi Silber
Reply to  EdB
October 28, 2018 11:28 am


I don’t know why you say it proves me wrong. It’s not my research.

“Prove” is not a scientific term.

I’ve seen that link and abstract already. Hard to evaluate, since the paper is pay-walled. I have reservations about it based on what is available. One paper is not enough to overturn all previous papers until it is adequately assessed. Have you read the whole thing? It seems some are willing to take it as “settling” the issue without the skepticism it warrants.

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