For those who don’t know, Ross McKitrick of the University of Guelph co-authored the first paper with Steve McIntyre debunking Michael Mann’s first Hockey Stick paper, MBH98. Ross wrote this essay in today’s Financial Post, excerpts are below. Please visit the story in that context here and patronize their advertisers. – Anthony
Flawed climate data
Only by playing with data can scientists come up with the infamous ‘hockey stick’ graph of global warming
Ross McKitrick, Financial Post
Friday, October 2, 2009
Beginning in 2003, I worked with Stephen McIntyre to replicate a famous result in paleoclimatology known as the Hockey Stick graph. Developed by a U.S. climatologist named Michael Mann, it was a statistical compilation of tree ring data supposedly proving that air temperatures had been stable for 900 years, then soared off the charts in the 20th century. Prior to the publication of the Hockey Stick, scientists had held that the medieval-era was warmer than the present, making the scale of 20th century global warming seem relatively unimportant. The dramatic revision to this view occasioned by the Hockey Stick’s publication made it the poster child of the global warming movement. It was featured prominently in a 2001 report of the U.N. Intergovernmental Panel on Climate Change (IPCC), as well as government websites and countless review reports.
Steve and I showed that the mathematics behind the Mann Hockey Stick were badly flawed, such that its shape was determined by suspect bristlecone tree ring data. Controversies quickly piled up: Two expert panels involving the U.S. National Academy of Sciences were asked to investigate, the U.S. Congress held a hearing, and the media followed the story around the world.
The expert reports upheld all of our criticisms of the Mann Hockey Stick, both of the mathematics and of its reliance on flawed bristlecone pine data.
…
Most of the proxy data does not show anything unusual about the 20th century. But two data series have reappeared over and over that do have a hockey stick shape. One was the flawed bristlecone data that the National Academy of Sciences panel said should not be used, so the studies using it can be set aside. The second was a tree ring curve from the Yamal Peninsula in Siberia, compiled by UK scientist Keith Briffa.
…
But an even more disquieting discovery soon came to light. Steve searched a paleoclimate data archive to see if there were other tree ring cores from at or near the Yamal site that could have been used to increase the sample size. He quickly found a large set of 34 up-to-date core samples, taken from living trees in Yamal by none other than Schweingruber himself!Had these been added to Briffa’s small group the 20th century would simply be flat. It would appear completely unexceptional compared to the rest of the millennium.
Combining data from different samples would not have been an unusual step. Briffa added data from another Schweingruber site to a different composite, from the Taimyr Peninsula. The additional data were gathered more than 400 km away from the primary site. And in that case the primary site had three or four times as many cores to begin with as the Yamal site. Why did he not fill out the Yamal data with the readily-available data from his own coauthor? Why did Briffa seek out additional data for the already well-represented Taimyr site and not for the inadequate Yamal site?
Thus the key ingredient in most of the studies that have been invoked to support the Hockey Stick, namely the Briffa Yamal series, depends on the influence of a woefully thin subsample of trees and the exclusion of readily-available data for the same area. Whatever is going on here, it is not science.
Read the complete story at the Financial Post
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Global Warming Profiteers Exposed: AGW Is Not and Never Was a Crisis
http://www.dakotavoice.com/2009/09/global-warming-profiteers-exposed-agw-is-not-and-never-was-a-crisis/
“So Briffa extrapolates a single tree as a thermometer. We don’t use a real single thermometer as relevant but we should use a single tree as one? ”
Yes. A single tree can teleconnect to ENSO, the NAO, and the AMO. I’m sure the folks at RC will have proof of it very soon.
“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 ”
Warms the heart to read that doesnt it. Now I aint a big fan of Mann, but given the abuse he has taken I like to read what the NAS said about him. Not what his enemies pretend they said.
This should be posted every single time his name is mentioned.
Nice one……
“Whatever is going on here, it is not science.”
Quoted for truthiness…
Jordan says:
The answer to your question about the GCMs is none. For one thing, the GCMs do not incorporate the hockey stick into them in any way. Furthermore, it makes no sense talking about the blade being lost. We have a variety of different sources (including, but not limited to the instrumental temperature record) for the blade. The question regarding the blade is really a question about how well these temperature proxies are good proxies for temperature and what that then says in regards to what say about past temperatures, not questions about whether we really have had significant warming in the past century.
And, at any rate, the GCM’s climate sensitivity comes out of the physics that goes into them. As it happens, their range of sensitivities does about mirror the range determined by empirical data. However, that empirical data involves more than just the 20th century temperature trends (things like the last glacial maximum and the climate response to the Mt Pinatubo eruption in the early 1990s). In fact, the 20th century temperature trends do not provide a very strong constraint on the climate sensitivity primarily because of the uncertainty in the aerosol forcing.
Don Keiller (09:56:43) :
As a plant physiologist I can say without hesitation that points 3 and 4 do not agree with the accepted science.
Good to have another plant physiologist on board, and I concur.
I sincerely hoped that there was no response from RC. If I had an answer it would be to refute the findings of Steve M. But the reaction full of anger, hatred, leaves the impression that MS is right on the vein. I think we have to wait a few days to have the idea of the damage that was caused by AGW at the castle. Seems to be much worse than we thought …
RC has thier rebuttal. Essientially they make light of the whole matter and blame M&M, Anthony et als on creating a story where one doesn’t exist. I tried to find thier rationalisation for Yamal. It was hard to seperate the blarney from the “science”, but here is thier defense of Biffra:
“McIntyre has based his ‘critique’ on a test conducted by randomly adding in one set of data from another location in Yamal that he found on the internet. People have written theses about how to construct tree ring chronologies in order to avoid end-member effects and preserve as much of the climate signal as possible. Curiously no-one has ever suggested simply grabbing one set of data, deleting the trees you have a political objection to and replacing them with another set that you found lying around on the web.”
What they failed to mention was the fact that McIntyre had to scour the ftp sites because Biffra wasn’t forthcoming with the data. Perhaps if Biffra would have posted archived data from his study, McIntyre wouldn’t had to grab datasets “lying around the web”. Otherwise, they claimed that Biffra’s alleged cherry picking was just his attempts to “perserve the signal”. Not one bit of statistical evidence that this preservation of the signal was in fact represenative of the past climate at Yamal and envrions.
Long on invective, short on mathematics or science.
Elmer:
The issue isn’t figuring out the proper temperature profile for 1850-2009 per se. The instrumental records are sparse, have bias, etc. – but they are a direct scientific observations of well understood phenomena. We’d clearly prefer to use the actual instrumental data for this period if we were making the best historical temperature reconstruction possible.
The point of using tree rings is to reach further into the past. Before you can use your tree rings to “measure temperature,” they have to be calibrated into reasonable proxies for temperature. Much like an odometer in a car needs to be calibrated against a yardstick, or a long string used to measure some irregular surface gets marked off on a yardstick.
But when you’re doing a calibration, you need to demonstrate that what you’re doing really is a solid proxy for a direct measurement. If you switch your car’s tires out for monster truck tires – your calibration is going to be atrocious. Or if your string shrinks when wet.
What’s going on here is that all the trees in the area are not equally good at measuring temperature. You can come up with a very large number of common sense reasons why two trees with identical genetics don’t have identical tree rings.
This means that you need to accumulate enough tree cores for statistical averaging to weed out many of the issues. (There’s a rock under this tree, that tree is in nitrogen poor soil, this other tree was repeatedly used for stropping by something large, etc.)
For years the aggregate data has been available. That is: It has been known that there was a set of cores from Yamal that have a general hockeystick shape.
But the aggregate data doesn’t say exactly how many trees were used, nor what the individual profiles were like. (At least, the raw profiles haven’t graced Science, Nature, or my other journals. Neither directly nor in the suplemental information.)
Now that the raw data is available, the number of cores used for the most recent period is rather shockingly low. Additionally, the list of raw cores used does -not- include some relatively nearby and contemporaneous cores.
If we went back to the odometer analogy, this is somewhat like (for whatever reason) including the single car with monster truck tires in your very small pool of test subjects. While excluding all the vehicles from the car dealership next door.
If you use that calibration as your basis for calculating “miles per gallon” or “how far can a car go before falling apart” or “How far has this car traveled”, you’re going to get decidedly odd results.
After your “tree proxy” is calibrated against temperature, you’re going to want to use it to extrapolate that same calibration into the past. If the calibration is faulty, then the temperature profile is faulty.
Scott A. Mandia,
How about some commentary on Caspar Amman in your link:
http://bishophill.squarespace.com/blog/2008/8/11/caspar-and-the-jesus-paper.html
If indeed the generations of chronologies since Briffa’s Yamal all have the same DNA, it would seem we’ve been swindled, and some industrious journalist need to dig out all the details for someone like Bishop Hill to summarize for laymen (such as myself) and all policymaker to read. Meanwhile, as we wait for the political shakeout, there are plenty of us who are actually quite curious about the science.
Since there are clearly two distinct, equally capable “sides” to this issue (Briffa and McIntyre), and both disagree about the efficacy of what the other spliced onto the sub-fossil record, how about the following experiment: “teams” from both sides select an acceptable subset of trees from any northern Urals or Yamal forest, have an “approved” dendro expert accompanied by Steve or Anthony, (any sceptics with time on their hands) to the Yamal (can’t wait?); gather an approved number of new rings. Analyzed them in an approved setting using an agreed-upon method, making all data available online. Splice them onto the old record with an agreed-upon method.
This controversy will not kill off dendrochronology, or even dendroclimatology, but one might hope for some better dendro records and practices as a consequence.
Indiana Bones (12:13:00) :
But the mainstream is… warming to the cool – George Will yesterday:
http://www.washingtonpost.com/wp-dyn/content/article/2009/09/30/AR2009093003569.html?sub=AR
He may even be the champion to follow this story to publication.
________________________
Indiana, did you check out the comments on Mr. Will’s article?
The unwashed Warmie masses are having a fit of apoplexy over it.
I am shocked to see such vitriolic religious fervor. As a matter of fact it frightens me. I fear that one day blood will be shed over this issue. All it might take is a major natural disaster and a few jingoistic provocateurs.
J, note the appeal to authority here. Not much information about how the preservation of the climate signal was achieved in Briffa. Some secret algorithm, perhaps? We would all love to see it.
[snip] Dorlomin. NAS panel told that MBH methodology and proxies are flawed and not to be used again, but could not rule out it was or was not warmer in MWP. “Scientists” in the meantime used those same hockey proxies again and again, Kaufman hockey stick being the last example.
Joel Shore,
your claim to have a number of Hockey Sticks is a true statement if removed from a reference to supporting the alledged uniqueness of the recent temp highs. Real Climate posted a number also. The ones that had nothing to do with temperature were the only ones that do not have statistical problems or more.
Please post YOUR list so we can also debunk it.
“at any rate, the GCM’s climate sensitivity comes out of the physics that goes into them.”
Ahhh yes. The ASSumed climate sensitivity based on raw radiative physics. You don’t think that resulting sensitivity might change based on other physics in the system do you?? YOU KNOW, like cloud type, actual moisture content, sulphur compounds, carbon black, ozone… Funny thing is, there are a lot of confliciting papers and reports on these issues, yet, y’all claim to have TRUE KNOWLEDGE skillful enough to Project out 100 years or more (even though it is well known that slight errors in a calculation can propagate to high levels)!! Y’all rate right up there with Bozo the Clown!!
HAHAHAHAHAHAHAHAHAHAHAHAHA
I apologise for the off-topic, but please also note that climate change is wiping out Walruses. This piece of “research” is brought to you by some idiot in a weatherproof anorak, with a wallet full of my taxes. This truly is the age of stupid.
Don B (08:18:14) :
Here is a general invitation by Roger Pielke, Jr. to educate Ben on this Yamal revelation:
http://rogerpielkejr.blogspot.com/search?q=
Here’s a direct link to the (excellent) discussion itself:
http://cruelmistress.wordpress.com/2009/10/01/hockey-stick-redux/
The real issue to be addressed by the defenders of Dr. Briffa and the publishing journals is – why the delays and stonewalling?? Refusing to provide the details of one’s methodology is NOT scientific method. For nine years?
Why should a relative handful of alarmists abuse the checks and balances the method provides to all scientists? We would like to hear an explanation for the need of qualified researchers to file Freedom of Information requests to obtain data used by publicly funded science. Neither Briffa, the journals, CRU or any institution other than the Royal Society demanded transparency.
Rather shameful it seems.
re Steve m “What would you say are variables in the size of a tree ring? Temperature? CO2? Rainfall? Nutrients in the soil? Amount of sunlight? Intensity of sunlight? Length of the growing season? all the above?”
All of the above and in a non-linear manner. Trying to deconvolute one factor from another is to all intents and purposes impossible.
The fact that a few trees correlate with temperature during the calibration period
is immaterial. Correlation is not cause and effect. The relationship is likely fortuituous and there is no evidence that the relationship holds outside the calibration period.
TREE LINES on the other hand are a much more reliable indicator and they are still about 100km South of previous values in the Yamal region.
Ergo today’s temperatures are not “unprecedented”
Jason S (08:34:58) :
Real Climate’s response to the claim that we have been waiting 10 years from Briffa’s data:
“[Response: The russ035w data has been ‘lying around’ on the web since 2001 (at least) judging from the file stamps. And there have not been ’10 years’ of requests. That’s just crap. – gavin]”
What say WUWT? Sorry if you’ve already answered.
As was mentioned earlier, file stamps really only indicate either file creation date or last modified date. But the point here is that, until Briffa released his data, no one knew what data sets he used. Just because I have access to a file does not mean that I know you have used it, unless you tell me you did. Briffa never said I did or did not use that file. That’s the big deal, Gavin. Without knowledge of what data was used, reproducibilty is impossible. Failure to release details of which data series are involved in your study is just cr@p!
kuhnkat (12:39:30) :
Scott A. Mandia,
How about some commentary on Caspar Amman in your link:
http://bishophill.squarespace.com/blog/2008/8/11/caspar-and-the-jesus-paper.html
Aw, you beat me to it. I was just going to post that link for Scott myself.
I’m no scientst, but I believe the scientific method is:
1. Develop a hypothesis
2. Test the hypothesis
What these “scientists” seem to not understand is that “Testing” is trying to prove it wrong, not trying to prove it right.
http://www.calgaryherald.com/health/Climate+fears+based+lies+Calgary+told/2058176/story.html
(Myself previously)
“I’m no scientst”
Obviously not, since I can’t spell it correctly, or even the same way twice in a row :-{