From the Telegraph:
The ‘hockey stick’ that became emblematic of the threat posed by climate change exaggerated the rise in temperature because it was created using ‘inappropriate’ methods, according to the head of the Royal Statistical Society.
By Louise Gray, Environment Correspondent
Professor David Hand said that the research – led by US scientist Michael Mann – would have shown less dramatic results if more reliable techniques had been used to analyse the data.
Prof Hand was among a group of experts charged with investigating the “climategate” email scandal that engulfed the University of East Anglia’s Climatic Research Unit (CRU) last year.
Sceptics claimed that the hacked messages showed scientists were manipulating data to support a theory of man-made global warming.
However the review, led by Lord Oxburgh into the research carried out by the centre, found no evidence of ”deliberate scientific malpractice”.
Lord Oxburgh said the scientists at the research unit arrived at their conclusions ”honestly and sensibly”.
But the reviewers found that the scientists could have used better statistical methods in analysing some of their data, although it was unlikely to have made much difference to their results.
That was not the case with some previous climate change reports, where “inappropriate methods” had exaggerated the global warming phenomenon.
Prof Hand singled out a 1998 paper by Prof Mann of Pennsylvania State University, a constant target for climate change sceptics, as an example of this.
He said the graph, that showed global temperature records going back 1,000 years, was exaggerated – although any reproduction using improved techniques is likely to also show a sharp rise in global warming. He agreed the graph would be more like a field hockey stick than the ice hockey blade it was originally compared to.
“The particular technique they used exaggerated the size of the blade at the end of the hockey stick. Had they used an appropriate technique the size of the blade of the hockey stick would have been smaller,” he said. “The change in temperature is not as great over the 20th century compared to the past as suggested by the Mann paper.”
…
Prof Hand praised the blogger Steve McIntyre of Climate Audit for uncovering the fact that inappropriate methods were used which could produce misleading results.
======================
Complete article here
Wren (11:33:02) :
“The shape of Mann’s graphs aren’t identical, if that’s what you mean, but both swing upward on the right like a hockey stick’s blade. Incidentally, none of the graphs were ever smooth lines like an actual hockey stick.”
OK, But Smokey has a point in that Mann 1998 reproduces Medevial WP
less than Mann 1999. However, every sceptic forgets or overlooks that
Mann 1998 has standard deviations indicated, which means that single
high temps in the MWP, rising to the level of average North Hemisphere
temp now are probably the regional warm periods you are missing. Whilst
the single low temps in MWP are due to geographical enlargment into
regions not affected by MWP. This is the right approach, because in the
AGW problem we need to go global.
——-
Why do you continue to mischaracterize McIntyre’s and Wegman’s criticism of the hockey stick as “debunking” ?
Webster’s defines debunk as “to expose the sham or falseness.”
—-
No, that you inform us of this, I would not say McIntyre debunked Mann;
M&M pointed out methodological weaknesses and thus contributed well.
But, Mann did not misapply PC analysis on purpose, he was just hasty and
did not consult experts (who does in normal science).
George E. Smith (10:34:31) :
“”” Gilbert (16:02:14) :
bob (09:13:00) :
Has McIntyre shown that the statistical methods did indeed produce different results, rather than could have produced misleading results.
In other words, any evidence that the hockey stick graph is wrong?
—————
Macintyre probably thinks he has; but, there have been 3 or 4 external
reviews, which support McIntyre on statistical methods, but find that
it doesn’t affect results much. The latest by Prof. Hand says that the hockey
stick shoul be a Field hockey stick; Mann disagrees citing a previous
review also including a statistician.
But, probably in the paleoecological area a lot of new evidence could
be produced and change the situation to some degree.
If it makes Wren happy, I’ll put it this way: M&M falsified Mann’s chart, which preposterously showed no MWP.
And if Mann would man-up and disclose his data and methodologies, the rest of his charts would be falsified as well. But Mann has been too well rewarded financially and with his status among the closed clique of climate grant beggars to stop generating his highly questionable charts.
All Mann needs to do is produce a hockey stick shaped chart covering the same time frame, showing the same temperatures, by using raw data and methods that he is willing to share with McIntyre and McKittrick. If that ever happens… pass the popcorn!
But that won’t happen, because Michael Mann knows he would be completely discredited. Volumes of data show not only a MWP, but several warmer periods during the holocene, thus falsifying the bogus claim that current temperatures are anything unusual.
Wren (11:33:02) :
“The shape of Mann’s graphs aren’t identical, if that’s what you mean…”
No, that is not what I stated or mean, which was: that particular Michael Mann Hokey Stick chart – the best one by far for the IPCC’s purposes, and the chart that catapulted Mann to stardom and grant heaven – was debunked, and that is why the IPCC can no longer use that chart. You’re doing everything possible to avoid facing that fact.
Keep digging that hole deeper.
—–
It was not debunked.
Webster’s defines debunk as “to expose the sham or falseness.”
Not even McIntyre or Wegman said the hockey stick is false or a sham.
Of course you may have your own definition of “debunked.” Humpty Dumpty was like that.
When _I_ use a word,’ Humpty Dumpty said in rather a scornful tone, `it means just what I choose it to mean — neither more nor less.’
From Alice Through The Looking Glass, Chapter VI
Smokey (10:27:51) :
mikael pihlström (09:55:51) :
“You are fixed on Mann or the MBR 1998 graph.”
No, that is projection. It is you and Wren who are fixated on Mann’s Hokey Stick graph. When Wren first brought it up, I pointed out:
– – – – –
Your difficulties with logic is evidently due to yourself being torn
between two haystacks:
On one hand you want to keep Mann 98 (the only one true in your op.)
alive, so you can gloat
On the other you want the MWR to emerge as good as possible
In the choice between emotional reward and science, the true sceptic
chooses …
Smokey
And if Mann would man-up and disclose his data and methodologies, the rest of his charts would be falsified as well.
They could be falsified by new data from practising scientists perhaps;
but, not by M&M who have certainly tried, but can only rock the boat slightly.
You don’t recognize the fact that MWP signal will depend on the area and
other complicating factors.
Wren & mikael,
I’ll be out for a few hours. That should give you time to think about how to respond to my original comment.
Everything you’ve both said since has been a series of strawman arguments, by which you avoid admitting that the IPCC can no longer use Mann’s chart that I linked to several times above.
Mann’s scary chart was falsified. Mann is not willing to disclose his raw data and methods. He is hiding his devious methods and his statistical incompetence by blustering.
When I return, I expect you to either show that the IPCC is still using the chart in question, or concede the point.
Wren (10:40:17) :
Myth: the hockey stick graph has been proven wrong
http://www.newscientist.com/article/dn11646-climate-myths-the-hockey-stick-graph-has-been-proven-wrong.html
Arguments based on myths are phony.
Hah! Looking at that article, especially the “update” references, we find in 9/2008 that Mann had once again used “stripbarks” and methods which create hockey sticks out of red noise, and also an upside down Tiljander and subjective confidence intervals which make “likely” mean a 66-90% guess.
Then the New Scientist breathlessly announces as an “update”, ” It might even be hotter now than it has been for at least a million years,” referring us instead to a 9/2006 article where Hansen actually concludes in part, “Comparison of measured sea surface temperatures in the Western Pacific with paleoclimate data suggests that this critical ocean region, and probably the planet as a whole, is approximately as warm now as at the Holocene maximum and within ≈1°C of the maximum temperature of the past million years.” [my bold, and not that I know if Hansen is right or not.]
The New Scientist = The Post Normal Scientist?
mikael pihlström (12:05:19) :
George E. Smith (10:34:31) :
“”” Gilbert (16:02:14) :
bob (09:13:00) :
Has McIntyre shown that the statistical methods did indeed produce different results, rather than could have produced misleading results.
In other words, any evidence that the hockey stick graph is wrong?
—————
Macintyre probably thinks he has; but, there have been 3 or 4 external
reviews, which support McIntyre on statistical methods, but find that
it doesn’t affect results much. The latest by Prof. Hand says that the hockey
stick shoul be a Field hockey stick; Mann disagrees citing a previous
review also including a statistician.
But, probably in the paleoecological area a lot of new evidence could
be produced and change the situation to some degree.
—-
I think people skeptical of CAGW may be shooting themselves in the foot by stressing the Medieval Warming Period(MWP).
Suppose there was a MWP when average global temperature was as high as it is today. Obviously that level of temperature would be almost entirely a result of natural causes, not man’s activities. CAGW naysayers might claim this means recent global warming is a result of nature rather than man. Of course that “nature can affect climate, therefore man can’t” is in itself a logical fallacy.
Evidence points to man’s activities as a driver of the the rise in global temperature during the last century.
Temperatures continue to rise even when natural influences(e.g., La Nina and down-cyycle in sunspots) have a cooling effect.
So if nature alone can produce the warming some think happened a thousand years ago(MWP), think about the warming that could result from a combination of nature and man’s activities.
Smokey (12:33:45) :
Wren & mikael,
I’ll be out for a few hours. That should give you time to think about how to respond to my original comment.
Everything you’ve both said since has been a series of strawman arguments, by which you avoid admitting that the IPCC can no longer use Mann’s chart that I linked to several times above.
Mann’s scary chart was falsified. Mann is not willing to disclose his raw data and methods. He is hiding his devious methods and his statistical incompetence by blustering.
When I return, I expect you to either show that the IPCC is still using the chart in question, or concede the point.
=====
Smokey, there is little profit in you arguing against a point I never made. Obviously, the shape of Mann’s Hockey stick has changed, and I never said it hadn’t. But it’s still a shaft with an up-turned blade. We still call it a hockey stick because It still looks like a hockey stick.
Your continued claim that Mann’s Hockey Stick was debunked discredits you.
Smokey
“When I return, I expect you to either show that the IPCC is still using the chart in question, or concede the point.”
If the point is: ‘IPCC cannot use the original MBH1998’. The point could
possibly be conceded if the argument was better construed.
That IPCC is not using the said chart can be due to (1) a free choice
not to use it, or, (2) a constrained situation making it impossible to use
it.
Since both alternatives associate with numerous qualifications you
have presented in a non-coherent way in previous messages, it is
impossible to choose one or the other.
But, I regret that you make this a scholastic exercise and forget the
important questions.
How about asking the TREES if Mann was wrong?
“Receding glaciers in the Swiss Alps are exposing evidence of earlier warm Holocene periods. Researchers are discovering that green forests once existed under the ice and that the Alps were mostly greener than today….
Christian Schlüchter, Professor of Geology, and his team of researchers are studying remnants of ancient trees and peat that have been exposed by melting glaciers high in the Swiss Alps…
Examining carbon isotopes in a high-tech laboratory, he has been able to determine the exact age of the uncovered artefacts and precisely when and where the trees grew. The information allows him to piece together a pretty good picture of the glacial history in the Alps since the end of the last ice age. Some trees at very high altitudes even lived 600 years. Schlüchter says the equilibrium line that is the boundary between the feed and depletion zones of the glacier was as much as 300 meters (1000 ft) higher in elevation than today.”
Thank you P. Gosselin for translating this for us.
It’s really interesting watching my friends Wren and mikael squirm. They simply can not admit that the reason the IPCC doesn’t use that chart any more is because it’s been thoroughly debunked by McIntyre and McKittrick, followed by Wegman, et al.’s Senate testimony.
When I got back I re-read this thread from my post with all the charts @12:50:36 onward. Despite the facts presented by just about everyone else [Andrew being the exception in his single, erroneous post; he needs to check out Climate Audit], our cognitive dissonance-afflicted friends refuse to accept that the IPCC was forced to dump Mann’s chart — a chart that they dearly LOVED above all others.
The IPCC loved that particular Mann chart so much that they published it, what, six or seven times? Way more than any other chart in their Assessment Reports. And now they have to make do with pale, inadequate imitations, none of which has nearly the visual impact of Mann’s original chart.
The other charts are simply hockey stick shapes, which, as M&M showed, will be produced even with red noise as the input when using the Mann algorithm that they discovered by chance. Hockey stick shapes are produced by Mann’s algorithm even when baseball scores are the input.
But our friends seem to still believe that Mann’s iconic chart was voluntarily withdrawn by the IPCC for no good reason.
That’s what cognitive dissonance will do to CAGW believers. Fortunately, because of the questioning nature of the scientific method, skeptics are largely immune from Orwell’s doublethink: the holding of two contradictory beliefs at the same time. In other words, cognitive dissonance.
So, guys, let us know when the ice hits the equator. ‘K thx bye.
[snip – take a time out – we are all getting weary of Wren’s thread bombing -A]
Smokey (18:39:06) :
“But our friends seem to still believe that Mann’s iconic chart was voluntarily withdrawn by the IPCC for no good reason.”
“The other charts are simply hockey stick shapes, which, as M&M showed, will be produced even by red noise when using the Mann algorithm they discovered by chance.”
Common practice in science; you get a better version by working on the
material; MBH worked on it for a year and replaced MBH 1998 with MBH 1999,
no McIntyre around to pressure yet.
All Hockey stick versions are basically sound, reproducing both recent
warming and MWP. They have been examined with unprecedented care
by at least 4 different and independent experts. The last one Prof Hand’s
statement you can see at:
mikael pihlström (09:55:51)
Wren (13:13:34) :
So if nature alone can produce the warming some think happened a thousand years ago(MWP), think about the warming that could result from a combination of nature and man’s activities.
Tentatively, yes. And there is talk of the observed warming being only
slow recovery from the little ice age. This would be in the background.
A detailed analysis of how Mann’s Hockey Stick was debunked by one of the people who did the debunking: click [source]
“Prof Hand singled out a 1998 paper by Prof Mann of Pennsylvania State University, a constant target for climate change sceptics, as an example of this.
He said the graph, that showed global temperature records going back 1,000 years, was exaggerated – although any reproduction using improved techniques is likely to also show a sharp rise in global warming. He agreed the graph would be more like a field hockey stick than the ice hockey blade it was originally compared to.”
Proving that the good professor whatever he does know, knows nothing about Hockey. A stick used for real hockey (and I’ve played it on tarmac) might not be as long but is much more curved than the implement used in the inferior cold weather game.
See http://www.hockeysticks.co.uk/hockey_stick_head_shape.htm
In fact temperatures following a field hockey profile would require a rift in the fabric of space time that even Picard and LaForge would struggle to repair….
“”” mikael pihlström (11:33:43) :
George E. Smith (10:34:31) :
“But as for tree rings; a tree is a three dimensional object; it has a height, and a (roughly) circular crossection. When you core bore a tree, you get a one dimensional sample of that three dimensional object. “””
Well mikael. I’m not going to quote your entire argument; but the essence of it seems to be that tree borers are not bound by the Nyquist Sampling Theorem.
Well you’ve core bored hundreds of trees. But unless you killed them all and divied them up; I don’t see how you fill in the missing information that is lost irretrievably by inadequate sampling.
We had a crossection photo here just the last couple of months or so, that could heve yielded a host of completely different conclusions, depending on which radius, one happened to drill; and I’m sure that heaight changes would have also yielded dramatic changes.
I’m not saying it is worthless (other than for ring age), but it certainly isn’t adequate to simultaneously be a proxy for sunlight, temperature, water history, mineral changes due to flooding or other geological changes; etc etc.; all of which seem to impact wood growth.
People who gorw up on statistics seem to believe that the central limit theorem
can buy them a reprieve from non robust data prestidigitation. Nothing cicumvents violation of the Nyquist sampling criterion; which converts unknown out of band “signals” into eaqually unknown; but now in band aliassing noise; which cannot be removed except by throwing out perfectly legitimate in band signal information.
Our entire data communications structure and networks; depend intimately on the validity of the Nyquist Criterion; so wilful violation of it is not quite like a parking ticket that can be ignored.
It would be nice if pseudo dendrochronologists even mentioned the limitations of their proxy estimates.