It was 20 years ago, climate scientist Michael Mann published his famous “hockey stick” graph that he says “galvanized climate action” by showing unprecedented global warming.
Mann used the 20-year anniversary of the graph to opine on the “industry-funded” attacks “to discredit the iconic symbol of the human impact on our climate,” which Mann claimed had withstood criticism.
“Yet, in the 20 years since the original hockey stick publication, independent studies, again and again, have overwhelmingly reaffirmed our findings, including the key conclusion: recent warming is unprecedented over at least the past millennium,” Mann wrote in Scientific American on April 20.
However, the two Canadian researchers who found serious flaws in the “hockey stick” study’s data and methodology disputed Mann’s characterization of the graph’s legacy.
“For everyone else, the debate was about data and statistical methods,” Ross McKitrick, an economics professor at the University of Guelph in Canada.
“For Mann, judging by his rant, it was all a giant political conspiracy against him and his heroic crusade to save the planet. He still won’t acknowledge the errors in his work,” said McKitrick who co-authored a 2003 study with mining executive Steven McIntyre that challenged Mann’s work.
Mann’s “hockey stick” graph, first published in 1998, was featured prominently in the U.N. 2001 climate report. The graph showed a spike in global average temperature in the 20th century after about 500 years of stability.
The “hockey stick” went viral and become a rallying cry for environmentalists and politicians who opposed fossil fuels and wanted climate policies. Former Vice President Al Gore even featured the “hockey stick” graph in his 2006 film “An Inconvenient Truth.” The graph also came under intense criticism, even sparking an investigation by GOP lawmakers.
Global warming skeptics were heavily critical of the “hockey stick” graph, especially in the wake of McKitrick’s and McIntyre’s 2003 study. Their study found serious flaws in the proxy data Mann relied upon to estimate temperatures going back hundreds of years.
The Canadians’ 2003 study showed the “hockey stick” curve “is primarily an artifact of poor data handling, obsolete data and incorrect calculation of principal components.” When the data was corrected it showed a warm period in the 15th century that exceeds the warmth of the 20th century.
3/ in our papers, we did not take a position on modern warm period vs medieval warm period. We pointed out gross errors in Mann's methodology, defects in the most critical proxies, and false claims about skill and robustness (what Mann called his "dirty laundry" in a CG email)
— Stephen McIntyre (@ClimateAudit) April 24, 2018
McIntyre and McKitrick also published a study on Mann’s “hockey stick” graph in 2005.
However, Mann wrote that “dozens of groups of scientists” had validated his 1998 study. Mann specifically pointed to a 2006 U.S. National Academy of Sciences (NAS) report that “affirmed our findings in an exhaustive independent review published in June 2006.”
Even McIntyre said subsequent studies have “produced somewhat hockey-stick-ish temperature reconstructions,” but added, “none (NONE) of our specific criticisms of Mann’s methods, proxies, and false claims has been rebutted.”
“The NAS report did not vindicate him, it said his methods were biased, and his results depended on faulty bristlecone pine records that shouldn’t be used by researchers,” McKitrick told The Daily Caller News Foundation by email.
“The NAS panel also cautioned against conclusions about warming more than 600 years back and said uncertainties were being underestimated,” McKitrick said. “That criticism applies to many subsequent studies as well.”
Indeed, the 2006 NAS reviewers agreed with the “substance” of Mann’s study but noted “claims for the earlier period covered by the study, from AD 900 to 1600, are less certain,” Nature.com reported at the time.
The NAS noted the uncertainties were “not communicated as clearly as they could have been” and “confirmed some problems with the statistics,” but those problems only had a minor impact on the overall finding, Nature.com reported.
However, NAS reviewers were extremely critical of the U.N. Intergovernmental Panel on Climate Change featuring the report so prominently in its 2001 assessment.
“The IPCC used it as a visual prominently in the report,” Kurt Cuffey, a NAS reviewer told Nature.com. “I think that sent a very misleading message about how resolved this part of the scientific research was.”
At the time, Mann said he was “very happy” with the NAS’s results and in the years since used his experience in defending the “hockey stick” to effectively label himself as a martyr for fighting global warming. Mann said attacks against him continued despite other researchers validating his results.
“There is no legitimate scientific debate on those points, despite the ongoing effort by some people and groups to convince the public otherwise,” Mann wrote in April as part of a screed against his critics.
Mann asks
‘What more noble cause is there than to fight to preserve our planet.’
How about the noble cause of not misleading readers with biased methods and bad data?” McKitrick said.
Read more at Daily Caller
“The Canadians’ 2003 study showed the “hockey stick” curve “is primarily an artifact of poor data handling, obsolete data and incorrect calculation of principal components.” When the data was corrected it showed a warm period in the 15th century that exceeds the warmth of the 20th century.”
Their graph from that link is here:
Apart from the 15th century, there is little real difference between the MBH version and its correction. In particular, in the 20th century HS period, it is virtually identical.
The 15th century peak in the corrected version is ironic, because almost no-one now believes it is right. Most accounts, including those favored at WUWT, now have the LIA well under way by then, and the MWP being from about 950-1200 AD. MBH is often accused of “erasing” the MWP, but the usual notion of MWP does not come within their period.
In fact, the 15th century peak in the correction did not come from amended stat methods, but from the arbitrary exclusion of the main source of data for the period, which was the Gaspé cedars. Without them, there really isn’t enough data to form a curve at all, hence the spurious peak.
Oh Dear Nick – I know this must be a touchy one for you but really!
From Ross McKitrick’s “What is the Hockey Stick Debate About? (pdf), under “3.3 The Gaspé cedar”
“Another oddity in MBH98 is that some series are duplicated within the data base. One of these, the Gaspé “northern treeline” series is included as a separate proxy (treeline #11) but it is also in the NOAMER PC collation as cana036. The data begin in 1404, but the chronology is based on only one tree up to 1421 and only 2 trees up to 1447. Dendrochronologists do not use site data where only one or two (or zero!) trees are sampled. In fact the authors who originally sampled the Gaspé data don’t use any of the data before AD1600. When used as treeline #11, MBH98 listed the start date as 1400 and filled the empty first four cells by extrapolation. The misrepresented start date enabled them to avoid disclosure of the unique extrapolation; the extrapolation enabled them to include this series in the calculations going back to AD1400, rather than withholding it until the AD1450 step.
“We wanted to see what would happen if the Gaspé data were not introduced until AD1450. By rights we could have withheld it until 1600, and only used it once in the data base, but that much alteration to the MBH98 procedure turned out to be unnecessary. Simply removing the pre-1450 portion had a large effect on the final graph, as will be shown in the next section. We wrote up the red noise experiment and significance benchmarking material into a paper which was submitted to Geophysical Research Letters. This series was included in the North American “northern treeline” net work even though the Gaspé peninsula is nowhere near the northern treeline.
“We wrote up the information on the Gaspé cedar and the bristlecone pines and submitted it to Energy and Environment. Both papers were accepted and came out in February 2005.”
Removal of Gaspé was apparently not an “arbitrary exclusion” at all.
And it seems that including Gaspé wouldn’t have produced a usable series in any case. And then those in-filled cells and misrepresented start-date. Such perfect methodological integrity.
What was it that Steve McIntyre began calling you, when you were trying to controvert his hockey-stick work at CA? Oh, yes, “race-track Nick Stokes.” How did he come to choose that, one wonders? Perhaps it was your penchant for truth-telling.
I saw your post at moyhu about my manuscript, by the way, in which you repeated your arguments as though they’d not been falsified. More of the same.
Their basis for exclusion is that there were four missing years. But the Gaspé cedars still provided a large part of the data available in the 15th century. Excluding based on made up notions of perfection just diminishes what is known. And gives a nonsense result.
From McIntyre and McKitrick E&E 2005 (pdf): “The underlying [MBH98] dataset is based on only one tree up to 1421 and only 2 trees up to 1447. Jones and Mann [2004] point to the need for “circumspect use” of tree ring sites with few early examples. The early portion of the series fails standard minimum signal criteria [e.g. Wigley et al. 1984] and indeed fails the data quality standards Mann et. al. themselves listed elsewhere. The early portion of the series was not used by the originating authors [Jacoby and d’Arrigo, 1989; D’Arrigo and Jacoby, 1992], whose analysis only begins effective 1601. In fact, Jones and Mann [2004] do not use the Gaspé series as an individual proxy and only use the Jacoby-d’Arrigo northern treeline composite when it is adequately replicated after 1601.(my bold)”
So Mann himself, but only later, rejected use of Gaspé-like series composed of only a single tree. And his use of Gaspé ignored the pre-existing quality standards of the field.
Hardly “made up notions of perfection.”
The charitable diagnosis for MBH98 is incompetent, and that’s an extreme of charitable giving.
Mr Stokes, it appears that a U shaped graph is not much of a hockey stick nor is it cause for alarm.
“So Mann himself, but only later, rejected use of Gaspé-like series composed of only a single tree”
No he didn’t. Read your quote – it says that “Jones and Mann [2004] do not use the Gaspé series as an individual proxy”. It is included in the North America PC composite. The whole thing is a PC composite analysis, so whether it is included via a sub-PC or individually makes little difference.
AS to why the originating authors didn’t use 15th C Gaspé, the reason is simple. It was outside the time period of their reconstructions (remember, MBH was the first to go back so far). Their 1989 paper was titled
“Reconstructed Northern Hemisphere annual temperature since 1671 based on high-latitude tree-ring data from North America”
and the 1992 paper abstract:
“Reconstructions from 1682–1968…”
The bottom line is that when you are doing a recon, data even from one tree adds to your information. Removing it reduces information. M&M seem to be making up rules to try to exclude information.
Re Nick:
**The bottom line is that when you are doing a recon, data even from one tree adds to your information. Removing it reduces information. M&M seem to be making up rules to try to exclude information.**
Nick is full of it as usual. Mann was not adding one tree for “more information”. The Bristlecone Pine DOMINATED the series. The case is similar with Yamal. McIntyre pointed out 4 different situations where this occurred and Nick knows it very well. Now he tries to imply that M & M were “making up rules”. More BS here. Nick knows that Mann was the one making up rules or using statistical techniques that were not generally accepted. Nick, go tell this quote at Climateaudit..
The relevant paper is Wigley 1984, not Jacoby and D’Arrigo 1989 or 1993 (received 1992, Nick, revised 1993).
The title of the 1984 paper is “On the Average Value of Correlated Time Series with Applications in Dendroclimatology and Hydrometeorolopy” in J. Climatol. Appl. Meteorol. 23, 201-213.
Wigley 1984 shows that time series from the core of one tree does not meet the data quality standard. Nor does a series composed from the cores of two trees. The MBH98 construction is obviated up to 1447 on that criterion alone.
Not only that, but McI and McK E&E 2005 shows that Mann’s 4-cell infill back to 1400 materially changed the early part of the final series. That’s obviatiation number 2.
A series from one tree isn’t data at all, when one tree is all you’ve got for a global series.
Jacoby and D’Arrigo in fact did use Gaspé in their two reconstructions. But they only went back to 1671 in the 1989 paper because the shortest series ended in 1663. No infilling back to 1400. Imagine that. The Gaspé series is a stand-alone below 1428 and doesn’t qualify as data.
Likewise, their 1993 reconstruction also used Gaspé. But again the reconstruction went back only to 1683 because the shortest series ended in 1681.
Jacoby and D’Arrigo clearly displayed integrity toward their data that the authors of MBH98 equally clearly lacked.
No matter that the reconstructions themselves had no known quantitative relationship to temperature; like MBH98,99.
Your post is nothing but a misdirection, Nick. It appears you didn’t even consult the papers you referenced.
“when one tree is all you’ve got for a global series”
But they clearly didn’t have just one (or two). M&M took out all the Gaspé data, and still claimed to be able to reconstruct 1400-1450.
“Wigley 1984 shows that time series from the core of one tree does not meet the data quality standard”
Wigley wasn’t laying down standards. But in any case, as said, Gaspé was not the only data group. M&M still produced a recon. It can’t help to remove a subset for too few members; all that happens is that you have less trees for the recon than before.
“Jacoby and D’Arrigo clearly displayed integrity toward their data that the authors of MBH98 equally clearly lacked.”
No. They just had less data. There is no evidence that it was inadequacy of Gaspé that limited them. They just had less in total.
Pat,
“Not only that, but McI and McK E&E 2005 shows that Mann’s 4-cell infill back to 1400 materially changed the early part of the final series.”
No. What they showed is that if you use the 4 missing years as an excuse to remove 46 years of data, it materially changes the result (as also shown in the plot above). That is what they did. What I showed here is that if you simply infill the years, it makes very little difference what infill you choose. MBH reasonably made 1400-1403 the same as 1404. But if you set them to the maximum (or minimum) of 1404-1450, it still makes very little difference. That is because it is only 4 years in average of 50, over several data groups. And you retain the information from the other 46 years.
The issue of Gaspé is that it should not have been used at all. And that infilling Gaspé materially changed the early portion of the MBH98 reconstruction.
“Wigley wasn’t laying down standards.”
Here’s what Wigley, 1984 says in conclusion: “We have developed a theory for estimating uncertainties in the average set of correlated time series. … We have applied these results to tree-ring time series and to precipitation time series. … [The method] is a measure of the signal-to-noise ratio as used in dendrochronology [and] allows one to estimate the minimum number of cores required to reduce the loss of reconstruction accuracy to below any chosen threshold level and hence to estimate the maximum useful length of a tree-ting chronology.”
That’s pretty much deriving a standard.
“M&M still produced a recon.”
M&M E&E 2005 showed reconstructions with infilled and as-deposited Gaspé to demonstrate the disproportionate effect the infill had on the reconstruction. That didn’t remove data. It showed the impact of improperly altered data.
M&M GRL 2005 showed the Mannian methodological invention produces a hockey stick from trendless red noise.
Can anyone suppose Mann was surprised? His only surprise was probably that anyone figured out what he had done.
“No. They just had less data. There is no evidence that it was inadequacy of Gaspé that limited them.”
I wrote that the Jacoby and D’Arrigo reconstructions were limited by the shortest series. Not that Gaspé limited them. J&D had too much integrity to extend their reconstruction using data that could not support it.
Unlike MBH98, who had no compunctions about using bad data to achieve their end.
M&M E&E 2005 Figure 1 says they used the archived version of Gaspé, which goes back to 1404. They didn’t eliminate 46 years of data.
M&M: “The only difference between the two series is the extrapolation of the first four years in MBH98.”
Removal of those four points changed the early reconstruction. The early part of the MBH98 hockey stick included 22 series. Any well-behaved method would not be sensitive to the presence or absence of four points.
Removal of the false short-centering, of course, removed the hockey stick.
Pat,
“And that infilling Gaspé materially changed the early portion of the MBH98 reconstruction.”
Again, they didn’t test infilling, in 2003 or 2005. They made it sound as if they did, but what they actually did was remove a large chunk of data. Truly infilling just 4 years makes very little difference. Here is Ross trying to get around their misleading choice of words.
“M&M GRL 2005 showed the Mannian methodological invention produces a hockey stick from trendless red noise.”
They showed something about what happens to the first principal component P1. That is just a rearrangement – it has little effect when you put everything into a recon, as the plot I showed above demonstrates. If you do it the M&M way, you get exactly the same HS.
But their claim of P1 hockey-sticks used a shonky manoeuvre. They generated 10000 from red noise, but then, unannounced, selected the top 100 according to a “hockey-stick index”. That is, the 100 that most looked like a hockey stick. Then they selected at random from that top 100.
Thanks for the link, Nick.
Reading the exchange, both Ross and Steve McI point out that it is you who are wrong. They removed no chunk of data. They used Gaspé as archived and with the four infilled points as Mann modified it.
That’s the way I read M&M E&E 2005. There’s really no ambiguity: “Figure 1. NH Temperature Index. Top panel: MBH98 emulation; middle panel: using archived Gaspé version; bottom panel: using centered PC algorithm.
Here’s Steve from the linked page, “It’s one thing for you to do your usual Racehorse stuff to try to justify Mann, but I request that you stop making bogus accusations against us.”
That pretty much nails it.
They showed something about what happens to the first principal component P1
PC1 was Mann’s global temperature series, Nick. You know that. Mann’s opportunistic short centering elevated the Graybill strip bark bristle pine series into PC1. You know that, too.
If you do it the M&M way, you get exactly the same HS.
M&M E&E 2005 Figure 1 panel 3, which was done the proper way, purports the 15th century as warm as the 20th. Oops.
I use purports by the way, because the whole paleo-temp recon business is no more than pseudoscience. Here and here.
M&M GRL 2005 Figure 3 shows that when Mann’s series are combined using proper methods, the hockey stick becomes utterly trendless. A flat noisy line from 1400 right through the 20th century.
There was nothing “shonky” about anything they did. They showed that Mann’s short centering produced hockey stocks from trendless red noise 99% of the time. Then they displayed an example.
You’ve got no case, Nick. None whatever.
Pat,
“They used Gaspé as archived and with the four infilled points as Mann modified it.”
That is certainly the impression that the text in their paper conveys. But it is wrong. You’ve been misled. Ross let the cat out of the bag in the section you quoted above:
“We wanted to see what would happen if the Gaspé data were not introduced until AD1450. By rights we could have withheld it until 1600, and only used it once in the data base, but that much alteration to the MBH98 procedure turned out to be unnecessary. Simply removing the pre-1450 portion had a large effect on the final graph, as will be shown in the next section. “
Jeans S sums it up clearly:
“it means that Nick Stokes just confirmed what Steve and Ross have been saying last 10 years: if you (a) exclude Gaspe series from AD1400 network (as it should since it starts AD1403) (b) use PCA correctly (which downweights the few bad apples (bristlecones)), you obtain a “striking divergence” from the MBH98 results.”
And that is what they did, and plotted. The mechanism, as I showed in the code (not disputed), was that they replaced the four infilled years 1400-1403 with NA, as disclosed. Should be harmless with a proper treatment of missing values. But what they actually then did was to incorporate in the code a provision that any 50 year segment that began with a NA was excluded from the “roster”. That means, excluded from the analysis. That makes a radical difference. They claim that this is following a MBH rule, but MBH stated no such rule. They claim they can infer it. But no rational rule would exclude a set based on the first year of the 50 yr segment being missing, but with NA’s in any other year allowed. Their “rule” was invented for just one purpose – to exclude Gaspé.
“There was nothing “shonky” about anything they did. They showed that Mann’s short centering produced hockey stocks from trendless red noise 99% of the time. Then they displayed an example.”
Then why did their code select (with no disclosure) the top 100 of 10000 by hockey stick index (appearance), from which they chose the example. And from which Wegman selected 12 examples, to show the better known display of HS-like results?
Nick, you’re displaying apples and called them oranges. E&E 2005 Figure 1 shows the 15th century effects of using the archived version of Gaspé, and compares that with Mann’s 4-point infilled version.
There just is no doubt about that.
M&M also did a test to see what happens if the pre-1547 part of Gaspé is excluded, based on the fact that the early 15th century data contained only 2 series. Namely, fewer series than is typically recommended for a valid recon.
You’re calling up the later test and using it as a supposed refutation of the earlier test. M&M did both tests. So what? There’s nothing shonky about that.
The 10,000 series were described in the GRL 2005 article. So, they did 10,000 simulations using trendless red noise, of which 99% produced PC1 hockey sticks when the MBH98 method was applied. That’s 9900 PC1 hockey sticks. They then offerred 100 of these 9900 as representative examples. So, what? That’s not shonky at all.
They’re completely upfront about what they did. GRL 2005: “Computer scripts used to generate simulations, figures and statistics, together with a sample of 100 simulated ‘‘hockey sticks’’ and other supplementary information, are provided in the auxiliary material.” And that SI is here: ftp://ftp.agu.org/apend/gl/2004GL021750
You’re stitching up a case made of nothing.
Aside from the fact that this graph totally destroys the notion that there is nothing unusual regarding modern temperatures, it’s practically identical to Mann’s work.
“it’s practically identical to Mann’s work”
Yes. And yet McKitrick says that they were “misleading readers with biased methods and bad data”. Apart from the question of whether the criticism is justified, how can it be misleading when the corrected result is so similar?
As to modern temperatures, no-one thinks proxies are a preferable measure of that. The original HS graph shows, rather prominently, the proxy curve terminating in the same way as the M&M graph. The hockey stick shows the contrast with the instrumental rise since 1950 compared with the stability of previous centuries.
” this graph totally destroys the notion that there is nothing unusual regarding modern temperatures”
The graphs do no such thing.
Nick:
**how can it be misleading when the corrected result is so similar?**
Because they are both WRONG!
Thankyou for clarifying this Nick- your posts are very informative. It seems that the hockey stick is indeed valid.
So a graph that shows it’s been warmer in the past proves that the current temperatures are unusual?
What has been shown is that to get anything like the “hockey stick” you must use eithervery carefully selected data, dodgy statistical methods, or, as Dr. Mann did, both.
Sorry to be late, would like to see Nick Stokes explain this- Infilling 4 of 50 years is too small a group to affect result. But pulling one gaspe tree (or is it 2?) out of Mann’s grand set of PC proxies is not a small effect, creating a huge upshot around 1500 and falsifies the notion that today’s temp rise is “unprecedented” (isn’t that how you like to say it?). Of course, that result is obviously invalid, in fact 1500 is too late for the MWP. I get that, but doesn’t that prove the invalidity of Mann’s whole approach? Isn’t that what M&M have really established (among other things)? In fact, this point has been made to you and you avoid it by heading around the track for another distracting lap. Racehorse indeed.
‘… the MWP being from about 950-1200 AD.’
That is true.
He’ll get his in the end. The Hockey Stick will be relegated to the trash heap of scientific history with cold fusion, Piltdown Man, and other frauds.
It won’t even have the luxury of being in the “wrong” camp like luminiferous aether.
Spelling error – should be:
“Piltdown Mann”
‘What more noble cause is there than to fight to preserve our planet.’
The fact that our planet will be “preserved” with or without his “help” is irrelevant.
Still waiting for credible evidence of “industry-funded attacks”…
‘What more noble cause is there than to fight to preserve our planet.”
—-
Maybe Mann is pushing for his Nobel Prize to be awarded now-ish?
“Even McIntyre said subsequent studies have “produced somewhat hockey-stick-ish temperature reconstructions,” but added, “none (NONE) of our specific criticisms of Mann’s methods, proxies, and false claims has been rebutted.” ”
So basically McIntyre is saying that subsequent papers have replicated the hockey stick but there was something wrong with Mann’s methods in his original paper? Is that it?
subsequent studies have shown that if you can stomach using either cherry picked data, bogus statistics, both, you can get a “hockey stick.”
Why ask us? Spend some time at CA and decide for yourself. Or do you prefer others doing your thinking, like Kristi.
Mmmmm … planet preserves … yummy ….
Future historian will judge that the ‘hockeystick’ was not a ‘mistake’ or an ‘artifact of poor data handling’, but that it was a deliberate and dishonest attempt to bamboozle ignorants and politicians into believing that the planet was on the boil and that ‘something drastic had to be done’.
http://wattsupwiththat.com/2009/05/03/climate-science-fraud-at-albany-university/#comment-126075
[excerpt]
Here is further evidence of this deplorable behaviour from the warmist camp, excerpted from an article I wrote circa 2005 and published in E&E:
“Mann eliminated from the climate record both the Medieval Warm Period, a period from about 900 to 1500 AD when global temperatures were generally warmer than today, and also the Little Ice Age from about 1500 to 1800 AD, when temperatures were colder. Mann’s conclusion contradicted hundreds of previous studies on this subject, but was adopted without question by Kyoto advocates.
Scientists opposed to Kyoto have now been vindicated. As a result of a Material Complaint filed by Ross McKitrick of the University of Guelph and Steven McIntyre, Nature issued a Corrigendum in July 2004, a correction of Mann’s hockey stick. It acknowledged extensive errors in the description of the Mann data set, and conceded that key steps in the computations were left out and conflicted with the descriptions in the original paper.”
**************************
Later, the Wegman committee issued a scathing condemnation of the Mann hockey stick conclusions.
We knew Mann hockey stick was wrong all along, but it took Steve McIntyre to show us exactly how it was wrong.
However, it took years for Steve to uncover the truth. Meanwhile, the warmist camp has hatched many new alarmist falsehoods.
Detailed rebuttals a la McIntyre take much longer to prepare than it takes the warmists to fabricate new scary stories.
Better to just assume that everything that comes from the warmist camp is self-serving, alarmist and false. Recent history has shown that there is a 99% probability that you will be correct in this assumption, nine times out of ten.
*****************************
https://wattsupwiththat.com/2017/10/07/the-incestuous-nature-of-the-ipcc-reports/comment-page-1/#comment-2630925
[excerpt]
The Wegman Report fully supported McIntyre’s work and declared that the much-touted (by-the-IPCC) Mann hockey stick was broken.
Excerpts – Wegman Report
The debate over Dr. Mann’s principal components methodology has been going on for nearly three years. When we got involved, there was no evidence that a single issue was resolved or even nearing resolution. Dr. Mann’s RealClimate.org website said that all of the Mr. McIntyre and Dr. McKitrick claims had been ‘discredited’. UCAR had issued a news release saying that all their claims were ‘unfounded’. Mr. McIntyre replied on the ClimateAudit.org website. The climate science community seemed unable to either refute McIntyre’s claims or accept them. The situation was ripe for a third-party review of the types that we and Dr. North’s NRC panel have done.
While the work of Michael Mann and colleagues presents what appears to be compelling evidence of global temperature change, the criticisms of McIntyre and McKitrick, as well as those of other authors mentioned are indeed valid.
“Where we have commonality, I believe our report and the [NAS] panel essentially agree. We believe that our discussion together with the discussion from the NRC report should take the ‘centering’ issue off the table. [Mann’s] decentred methodology is simply incorrect mathematics …. I am baffled by the claim that the incorrect method doesn’t matter because the answer is correct anyway.
Method Wrong + Answer Correct = Bad Science.
The papers of Mann et al. in themselves are written in a confusing manner, making it difficult for the reader to discern the actual methodology and what uncertainty is actually associated with these reconstructions.
It is not clear that Dr. Mann and his associates even realized that their methodology was faulty at the time of writing the [Mann] paper.
We found MBH98 and MBH99 to be somewhat obscure and incomplete and the criticisms of MM03/05a/05b to be valid and compelling.
Overall, our committee believes that Mann’s assessments that the decade of the 1990s was the hottest decade of the millennium and that 1998 was the hottest year of the millennium cannot be supported by his analysis.
[The] fact that their paper fit some policy agendas has greatly enhanced their paper’s visibility… The ‘hockey stick’ reconstruction of temperature graphic dramatically illustrated the global warming issue and was adopted by the IPCC and many governments as the poster graphic. The graphics’ prominence together with the fact that it is based on incorrect use of [principal components analysis] puts Dr. Mann and his co-authors in a difficult face-saving position.
We have been to Michael Mann’s University of Virginia website and downloaded the materials there. Unfortunately, we did not find adequate material to reproduce the MBH98 materials. We have been able to reproduce the results of McIntyre and McKitrick.
Generally speaking, the paleoclimatology community has not recognized the validity of the [McIntyre and McKitrick] papers and has tended dismiss their results as being developed by biased amateurs. The paleoclimatology community seems to be tightly coupled as indicated by our social network analysis, has rallied around the [Mann] position, and has issued an extensive series of alternative assessments most of which appear to support the conclusions of MBH98/99… Our findings from this analysis suggest that authors in the area of paleoclimate studies are closely connected and thus ‘independent studies’ may not be as
independent as they might appear on the surface.
It is important to note the isolation of the paleoclimate community; even though they rely heavily on statistical methods they do not seem to be interacting with the statistical community. Additionally, we judge that the sharing of research materials, data and results was haphazardly and grudgingly done. In this case we judge that there was too much reliance on peer review, which was not necessarily independent.
Based on the literature we have reviewed, there is no overarching consensus on [Mann’s work]. As analyzed in our social network, there is a tightly knit group of individuals who passionately believe in their thesis. However, our perception is that this group has a self-reinforcing feedback mechanism and, moreover, the work has been sufficiently politicized that they can hardly reassess their public positions without losing credibility.
It is clear that many of the proxies are re-used in most of the papers. It is not surprising that the papers would obtain similar results and so cannot really claim to be independent verifications.”
Especially when massive amounts of public monies and human lives are at stake, academic work should have a more intense level of scrutiny and review. It is especially the case that authors of policy-related documents like the IPCC report, Climate Change 2001: The Scientific Basis, should not be the same people as those that constructed the academic papers.”
In the first figure — Reconstructed (50 year low pass) shows the sharp linear increase in 1900 – 1950 and there onward it only showed ups and downs with little linearity — only pause condition. According to IPCC global warming component starts from 1950 onward. That means after 1950 there is no realistic global warming.
Dr. S. Jeevananda Reddy
Good point Doc.
As shown by Nick, Warmunists have to pull all kinds of tricks and stunts to “show” an “unprecedented warming” after the LIA. Mann (and now, Nick) never met a cherry he didn’t pick. An impressive show, really.
Sadly, for the Warmunists, and though they try to hide this fact, they actually have two hurdles; in addition to “unprecedented warming, they have to show that CO2 is causing it. Problem is, it never has before. Oops.
“Problem is, it never has before.”
No problem – it’s rather obvious. CO2 causes warming if you put a whole lot of it in the atmosphere. That hasn’t happened before.
Who knew?
In the past and the present, Nature has no effect on the atmosphere.
Past higher levels of CO2 were all Man-made.
Maybe all the trillions of bucks spent to prevent CaGW should have been spent to build a DeLorean so we could go back and shoot that caveman that invented fire?
I thought it was those prior levels of 2000ppm – 7000ppm that tipped the earth so now it is hothouse uninhabitable
CO2 causes warming if you put a whole lot of it in the atmosphere.
Where’s your falsifiable theory of climate demonstrating that causality, Nick?
That hasn’t happened before.
Except for the ~6000 ppm of CO2 500 million years ago. And about 1200 ppm CO2 100 million years ago.
Also here
If adding or removing a tree changes the output curve, must mean the whole theory of tree rings as currently used is rubbish.
That mann is so full of crap
Since Grove and Switsur 94 till now the glaciological community has rejected en masse the hockey stick, to the extent that it eliminates the LIA. See if you can find a professional glaciologist who does not take for granted a global LIA. –AGF
The lie is the very bedrock of the leftist agenda. They use it continuously. And it works with the uninformed and/or ignorant. It has always been and continues to be the case because it works so well with their target audience.
Nick Stokes, look where the (paleo) climate science has gone:
this latest PAGES 2k compilation shows that you get a hockey stick no matter what you do to the data
https://climateaudit.org/2017/07/11/pages2017-new-cherry-pie/
https://strangeweather.wordpress.com/2017/07/11/the-hockey-stick-is-alive-long-live-the-hockey-stick/amp/
In the not too distant future this one graph could either be part of the dustbin of science history or part of the loyalty pledge for the next over reach administration. It has already been an official logo of an unrepentant UN agency. It could be resurrected as a huge red flag in massive stadium-sized rallies with goose stepping.
Back when I still believed in honesty, I thought that putting an algorithm in a model that produced the same graph result regardless of inputted data ought to have been sufficient to kill the issue.
Then I read the paper the following day, with the headlined rationalizations to explain it all away – presented by the press as ‘the real story’.
Enough propaganda can apparently bury anything.
Not sure if I posted this version of the current interglacial temperature anomaly – a climate change for beginners graph based on GISP2. The reason no one else has is because , I assume, you need to be familiar with it and the existence of the data series to as a foundation to participate in the discussion? I also assume Mann chose to ignore this assessment of reality from a cotiguous data set as no t the result he wanted. as he also ignored the historical record from people alive and writing at the time of what the actual climate was like, rather than manipulating his disparate proxy data sets. Same basic BS of being told we should prefer to believe partial extrapolations of misweighted and sparse climate models of non-linear effects set out as the certain words of god, heard through his IPCC priests, over the proven physics and the natural data. Really?
?dl=0
Note the bonus graph showing lack of significant CO2 correlation with the temperature change. Either leading or lagging, at this relatively insignificant level of anomaly.
“Not sure if I posted this version of the current interglacial temperature anomaly – a climate change for beginners graph based on GISP2”
The usual dishonest stuff, with the end strip marked as “Modern Warm Period” when the last data point was in 1855.
In what way is this “dishonest”? It uses the GISP2 data set to 1855, correct, and the real temperatures from HADCRUT4.4 to show the recent past,.These now overlap back to 1794. Do you suggest HADCRUT 4.4 is wrong or biased in some way? How is adding the real data from Greenland to the ice core readings to show the recent past in comparison “dishonest”?
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/icecore/greenland/summit/gisp2/isotopes/gisp2_temp_accum_alley2000.txt
For another assessment of the Greenland temperature range, using different gas proxies, there is Kobashi, reviewed with links here, Figure 4 seems apposite..
https://andymaypetrophysicist.com/kobashi-and-alley-gisp2-central-greenland-temperature-reconstructions/
This is also tailed with HADCRUT4.4. I don’t see any significant contradictions with my posted diagram, which is widely used, small time and magnitude shifts, yes, but substantively the same warm and cold periods, and nicely illustrating the fraud of Mann’s concatenated disparate data sets with his various “adjustments”, whatever they were, to eliminate the warmer historical periods, make pre industrial climate seem almost invariate, and make the current temperature appear to be higher than the several precedents this interglacial. Also denying the written historical record, of course.
Nothing unusual is happening here, honestly, on the facts.
This the data for Greenland to 2013.
http://www.dmi.dk/fileadmin/user_upload/Rapporter/TR/2014/tr14-06.pdf.