Reader Crosspatch writes in comments:
4241.txt is where Briffa Rob Wilson apparently believes he recreates what McIntyre is talking about the hockey stick showing up no matter what data you feed into it. Briffa Wilson creates randomly generated time series, feeds them in to Mann’s maths and bingo … out pops a hockey stick.
I first generated 1000 random time-series in Excel – I did not try and approximate the persistence structure in tree-ring data. The autocorrelation therefore of the time-series was close to zero, although it did vary between each time-series.
Playing around therefore with the AR persistent structure of these time-series would make a difference. However, as these series are generally random white noise processes, I thought this would be a conservative test of any potential bias.
…
The reconstructions clearly show a ‘hockey-stick’ trend. I guess this is precisely the phenomenon that Macintyre has been going on about.
Here’s the full email:
cc: edwardcook <REDACTED>, <REDACTED>, “David Frank” <REDACTED>, “Jan Esper” <REDACTED>, “Tim Osborn” <REDACTED>, <REDACTED>, “Brian Luckman” <REDACTED>, “Andrea Wilson” <REDACTED>, “rosanne” <REDACTED>, “Watson,Emma [Ontario]” <REDACTED>, “Gordon Jacoby” <REDACTED>, “Brohan, Philip” <REDACTED>
date: Tue, 7 Mar 2006 17:44:46 +0700
from: edwardcook <REDACTED>
subject: Re: Emailing: Rob’s Hockey Sticks
to: “Rob Wilson” <REDACTED>
Hi Rob,
You are a masochist. Maybe Tom Melvin has it right: “Controversy about which bull caused mess not relevent. The possibility that the results in all cases were heap of dung has been missed by commentators.”
Cheers,
Ed
On Mar 7, 2006, at 5:20 PM, Rob Wilson wrote:
Greetings All,
I thought you might be interested in these results.
The wonderful thing about being paid properly (i.e. not by the hour) is that I have time to
play.
The whole Macintyre issue got me thinking about over-fitting and the potential bias of
screening against the target climate parameter.
Therefore, I thought I’d play around with some randomly generated time-series and see if I could ‘reconstruct’ northern hemisphere temperatures.
I first generated 1000 random time-series in Excel – I did not try and approximate the
persistence structure in tree-ring data. The autocorrelation therefore of the time-series
was close to zero, although it did vary between each time-series. Playing around therefore
with the AR persistent structure of these time-series would make a difference. However, as
these series are generally random white noise processes, I thought this would be a
conservative test of any potential bias.
I then screened the time-series against NH mean annual temperatures and retained those
series that correlated at the 90% C.L.
48 series passed this screening process.
Using three different methods, I developed a NH temperature reconstruction from these data:
1. simple mean of all 48 series after they had been normalised to their common period
2. Stepwise multiple regression
3. Principle component regression using a stepwise selection process.
The results are attached.
Interestingly, the averaging method produced the best results, although for each method
there is a linear trend in the model residuals – perhaps an end-effect problem of
over-fitting.
The reconstructions clearly show a ‘hockey-stick’ trend. I guess this is precisely the
phenomenon that Macintyre has been going on about.
It is certainly worrying, but I do not think that it is a problem so long as one screens
against LOCAL temperature data and not large scale temperature where trend dominates the correlation.
I guess this over-fitting issue will be relevant to studies that rely more on trend
coherence rather than inter-annual coherence. It would be interesting to do a similar
analysis against the NAO or PDO indices. However, I should work on other things.
Thought you’d might find it interesting though.
comments welcome
Rob
REDACTEDREDACTEDREDACTEDREDACTED—
Dr. Rob Wilson
Research Fellow
School of GeoSciences,
Grant Institute,
Edinburgh University,
West Mains Road,
Edinburgh EH9 3JW,
Scotland, U.K.
Tel:REDACTED
Publication List: [1]http://freespace.virgin.net/rob.dendro/Publications.html
“…..I have wondered about trees.
They are sensitive to light, to moisture, to wind, to pressure.
Sensitivity implies sensation. Might a man feel into the soul of a tree
for these sensations? If a tree were capable of awareness, this faculty
might prove useful. ”
“The Miracle Workers” by Jack Vance
REDACTEDREDACTEDREDACTEDREDACTED—
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What bothers me is that we do have a very CLEAR hockey stick in the relatively past and yet nobody attempts to correlate it with CO2. Temperatures when we started to come out of the LIA were a pretty nice “hockey stick” if you were to do a 400 year plot. It would have been a pretty cold period (albeit with some noisy bumps up and down here and there) and then suddenly the temperatures take off skyward. Nobody is blaming that on human activity. So we do have evidence of various hockey sticks in the past. Heck, coming out of the last glacial was the mother of all hockey sticks. What set that off? It wasn’t gradual at all, it was *boom* glacial over! Hockey sticks happen all the time when you don’t have the full context and carefully pick your start and end times. We have one at my house most mornings.
I personally believe that the way we are measuring things is whack. First of all, the majority of the land on this planet is in the Northern Hemisphere. Land responds differently to things than ocean does. Temperatures over land can be quite noisy. I would expect that a global change that causes little noticeable change in the SH might cause a quite noticeable change over more of the surface of the Earth in the NH. Does CO2 have an impact? Probably. I’m not convinced it has as much of an impact as is claimed, though. I think what has more of an impact are the normal cyclical things we see such as the various multi-decadal oscillations in the atmosphere plus likely oscillations in ocean currents plus things like changes in cloud cover, solar spectrum, solar wind/cosmic ray impacts, etc. These things move about at their own pace. I believe that sometimes they just sort of accidentally line up in such a way to amplify their impact. It is like looking at a signal that is the sum of a lot of different frequencies. At various points they all add up and you might get a large peak. At other points they might all add up in the opposite direction and you get a large dip. The problem is that the periods of these things in nature are only approximate. They aren’t on a fixed period. A cycle might last anywhere from 40 to 70 years. So now you take that same mix of frequencies and begin to randomly frequency modulate them and the result is even more unpredictable. I believe that sometimes things just all line up in the “wrong” direction and we get a major impact. Maybe we have a solar grand minimum (or maybe a few more or less back to back to back [Wolf Minimum 1280-1350, Spörer Minimum 1460-1550, Maunder Minimum 1645-1715, Dalton Minimum 1790-1820] and maybe you get the Atlantic and Pacific oscillations and ENSO all lining up just right and kaboom, it gets really cold where any of those events would not by themselves be enough to create a cold period but all lined up together they can make a doozy. And that probably only happens at very infrequent intervals.
Or heck, maybe the distribution of cosmic rays in the space through which the solar system flies isn’t even. Maybe every 100,000 years or so we break out into an area that has less of them and so even with a given amount of solar activity there are fewer cosmic rays available to reach the inner solar system and cloud cover drops and for a relatively little while (15% of the time, roughly) Earth has less cloud cover and warms up and then the density of those rays begins to increase again and slowly, over several thousand years, the cloud cover increases and we get progressively colder until we slip into another “shadow” of some sort and the number of these cosmic rays is again reduced.
I can speculate all day because the whole thing is open to speculation. Nothing has been nailed down except billions of dollars of taxpayer money that is being tossed into programs to “save” the planet from becoming exactly what it has been in the not so distant past and survived that period just fine. You don’t have to go back so far in geological time to find a period when CO2 and temperatures were higher than today and we survived. No “saving” required. It’s just nuts.
crosspatch,
I don’t see any hockey stick shape coming out of the LIA. There is simply a rising temperature trend line [note the green line showing that the trend is slowly decreasing].
The hockey stick shape is an artifact of using an arbitrary zero baseline, or an arbitrary temperature baseline for the x-axis. A zero baseline axis is used deliberately, rather than an honest trend line, because it creates a scary looking chart. But when plotting a long term trend line, the hockey stick shape vanishes.
Nothing unusual is happening, it’s just natural variability.
“I do not think that it is a problem so long as one screens
against LOCAL temperature data and not large scale temperature”
So, with this specualtion, we must conclude that the hockey stick that this method generates when fed real data (presumably screened against LOCAL temp data) is really real. Not like the bogus hockey stick the method generates when fed bogus data.
Did he really not notice what a logical pretzel he had twisted himself into?
eyesonu says: (November 28, 2011 at 8:17 am) wrote:
“You make a valid point.
There could be major cracks within the ‘Team’ foundation and as the truth unfolds any ethical / honest players may step forward. I hope it becomes a landslide when it begins. Nevertheless, it should have happened years ago.”
If and when criminal charges are ever brought against one or more players on the “team”, maybe the landslide can be hastened by offering prosecution immunity to a few of the tier 4 bench warmers. That approached worked against the mafia; and somehow I believe that faced with possible jail time, many “ower-tier team members might rat out their bosses.
“The possibility that the results in all cases were heap of dung has been missed by commentators.”
You deniers have taken this phrase out of context, and it’s a typo on top of that. I originally wrote:
“The possibility that the commentators in all cases were heap of dung has been missed by the results.”
Cheers,
Ed
/sarc
I’d like to know why the hell these people are using Xcel? [snip] Are you kidding me? Not even Origin? Or Igor? As in proper programs for data analysis? Xcel is a spreadsheet and can do some rudimentary statistics, but scientists should not be using it for data analysis in anything other than rough estimate sort of stuff.
@Jeremy says:
November 28, 2011 at 6:54 am
exactly – I respect Robs observations on this problem, he gave a heads up to the top nobs, ball in your court sort of thing, would any of us potentially end our career going further?
he knew the story, how else to put it?
I think this belief has motivated many in the warmist camp, and has made most fence-sitters and journalists reluctant to criticize warmism. One inference I draw is that the failure of renewables to deliver on their promised payoffs, and the growing exposure of their downsides, and the cutbacks in Euro subsidies, plus the ongoing scandals about sweetheart funding deals, will invisibly erode mainstream support for warmism.
Our side ought to compile a list of notable “points of interest” in the 2.0 e-mails, in brief, bullet-point form. How about a thread with a starter list provided by the thread-author, with an invitation to WUWTers to add on to it?
Wouldn’t you also be able to generate a reverse hockey stick from the tree-ring data? If you instead take those series that have really good correlation with cooling starting from the MWP up until the LIA and then process them identical to the way that Mann did, I would think you would end up with the blade starting at the MWP and the flat “handle” temps extending all the way up to 2000.
Galane says
So Rob Wilson suspected something was hinky with the plotting program and conducted a proper scientific test of the program and proved beyond any doubt the program was rigged – yet chose to keep it quiet?
————-
Nope. He told a lot of people about it. As is crystal clear if you actually read the email.
Also he produced a hockey stick from noise, but concluded that it was not relevant to the analysis of the real data. In other words it was a hockey stick but not the same hockey stick.
So the email is actually evidence that what skeptics say is considered, checked and judgement applied about whether it is relevant.
Crispin in Waterloo says
Why is it wrong? Principle Components analysis is not a process applicable to the problem Mann was working on. McIntyre’s objection was not specifically that the result was a hockey stick (which it inevitably happens to be) but an observation that the mathematical approach used was invalid. Whether it produced hockey sticks or not would not address the root problem which makes them appear out of the mathematical void.
—————
So what happens if the source data actually contains hockey sticks?
Does a hockey stick produced by noise look exactly the same as a hockey stick produced by aggregating data made up of hockeysticks? Can they be told apart? Is the amplitude different or the point of inflexion at a different place?
If they can be distinguised then the whole objection to Mann’ s method is bogus.
Maybe it’s time for you guys to come up with a mathematical proof that Mann’s method is incorrect or at least some formulae that define when the method is appropriate and when it is not. Then at least you will have something rigorous to say.
So far it’s just been endless repetitions of opinions and I don’t know enough about the methods involved to make an assessment of who is talking out of their backsides.
Apparently, there’s a great place these guys could put their mathematical “skills” to good use.
http://rivals.yahoo.com/ncaa/football/news?slug=dw-wetzel_football_hostage_illegitimate_bcs_112911
They would do just great at determining the BCS rankings! Just imagine, Penn State plays for the national championship every year!
That settles whether Michael Mann has standing against the Canadian guy for suit. He really DOES belong in the State Pen. If he generated that and then tried to get funding to claim ‘more research needed’ he’s guilty of funding fraud for sure.