“YOU KNOW WHAT THE PHRASE REALLY MEANS.”

Mann said the “trick” Jones referred to was placing a chart of proxy temperature records, which ended in 1980, next to a line showing the temperature record collected by instruments from that time onward. “It’s hardly anything you would call a trick,” Mann said, adding that both charts were differentiated and clearly marked. – http://www.washingtonpost.com/wp-dyn/content/article/2009/11/20/AR2009112004093.html

But what I don’t understand is why Mann said “It’s hardly anything you would call a trick” at one point and then later said “members of the public may not appreciate the lingo or jargon (e.g., ‘dirty laundry’ or ‘trick’) that scientists often use when communicating with each other about their science.

“Why? Just to eat up time from his personal life?”

Because Michael Mann is not Phil Jones, and instead of having Mann tell us semi-contradictory versions of what Jones meant, it doesn’t seem that difficult to have asked Jones himself. And it seems like Jones has had a lot of extra free time over the past few months, so I don’t see it as that much of a burden.

If you zoom out far enough, and squint your eyes a bit, so you’re not distracted by those pesky details…

The reason for that is that I regard Argument from Authority to be a logical fallacy (hence the name, of course), and being the antithesis of the defining characteristic of my position, it would be hypocritical of me to rely upon it. I would much prefer to engage on the actual technical arguments rather that compare authorities.

But where relevant, I have in the past cited the peer-reviewed technical literature, books on the subject, and various web sites. It doesn’t surprise me, though, that people here are choosing not to read them or investigate the matter for themselves – it explains why the same points keep coming up again and again.

But since you haven’t read any of my past ‘screeds’, I guess you’re excused for not knowing that.

When you classify and judge the credibility of a web-site by the conclusion it draws, rather than the quality of the arguments, your own position becomes unfalsifiable. Because all opposing arguments are rejected as non-credible, simply because they oppose, there is no way for any valid opposing argument (should one exist) to lead to erroneous beliefs being corrected. Had you classified them as “unscientific” or some similar term, I’d have had no objection – but by labelling them as “Denialist”, you reveal that you’re judging by outcomes. Logically, I can make no headway against such a position.

I wouldn’t, in any case, reference Morano because he is principally a news aggregator. He doesn’t provide any technical arguments, he just links to other sites that do. And yes, he isn’t very fussy about the quality of his sources. Watts I would link to for things like the surfacestations project, and sometimes for general news. Any technical arguments I judge on their own merits, not those of their authors.

But your ad hominems about Morano and Watts are beside the point here. If you knew the subject area, even from the pro-AGW side, you would already know that the reconstructions were done broadly as I described. One of the climate scientists’ main defences against the charge of “hiding” stuff is that they were quite open about the divergence problem in the technical literature. The controversy is about how you interpret it. (They were a lot less open about the lack of correlation between the reconstructions and thermometers, but it was eventually – and very grudgingly – published in Wahl and Ammann 2007, as I’ve explained at length previously here.) And as for the rest of it, the problem I’m complaining about is precisely that the details of these calculations are not published in the technical literature. Everybody is having to laboriously reverse-engineer exactly what was done to construct these graphs, and why it was done, because the people who generated them are still keeping it a deep, dark secret.

Rob P. did at least link to some technical arguments, and if he hadn’t topped and tailed it with all the abuse, I’d have congratulated him on it. It’s rare for this site. But a complaint that I’m not citing enough Authorities, especially when any source that doesn’t accept AGW is rejected a priori as not being credible? Given that my entire stance is based on rejection of Argument from Authority? Oh, dear.

I don’t read most of Mr. Nullius’ screeds but from the few I have skimmed, one is left with the impression that he never provides a citation to the peer reviewed technical literature supporting his statements. In fact, he never provides a citation to web sites that support his statements. One can only conclude that the former do not exist and the latter consist of denialist web sites like Marc Moranos’ and Anthony Watts.

I’m not a liar. And DeepClimate is mistaken.

We could go into the details of whether DeepClimate using his own different emulation on the wrong graph really proves anything (he agreed with most of the points I made, anyway), but if people aren’t willing to assess arguments they see on the internet critically, there probably isn’t any point.
(For anyone who is interested, you can see all the different versions being discussed by looking on ClimateAudit, “Arthur Smith’s Trick”.)

It is inevitable in any controversy, scientific or otherwise, that the participants disagree, and each claims the other to be wrong. If every time someone was accused of being wrong, it led to accusations of libel and being banned from the debate, it would shut the debate down entirely. You would soon get an immovable orthodoxy, a standard version that nobody was allowed to deviate from, lest they be prosecuted and silenced. Is that what you want?

How can you reasonably talk about a controversy if neither side is allowed to say the other is wrong? Or rather, have it that one side is allowed to call the other a liar and a criminal, and then ban them from the debate so they have no means of replying?

But I do think it illustrates nicely the attitude to science of the true believers. The philosophical basis of modern science is falsification – that science proceeds by trying your hardest to prove it wrong. You examine the best arguments against the orthodoxy, and try to find any merit in them. Scepticism is Science.

If you don’t permit any opposing arguments, you can have no confidence that your beliefs are not riddled with holes and errors that you have missed. Everybody makes mistakes. Science works by trying to find and fix them. Shutting down debate kills the scientific process dead – and I’d like people to make careful note of which side here is trying to do that. Are you perhaps getting nervous?

The essential point of my argument is that the question is still open as to whether tree rings are really reconstructing temperature. DeepClimate does not discuss that point, and neither do you. All the nit-picking about precisely what was done in the calculation of what graph could (and should) be resolved immediately by the scientists simply publishing the exact details of how the calculation was done. It is a telling point that even DeepClimate has to reconstruct it in his own emulation of what was done rather than simply getting the actual algorithm and data used from the published record.

But all of that just distracts from the essential point: if the “reconstruction” diverges from the measured temperature, is it really reconstructing the temperature, and is it good science to chop off the bits that don’t agree, fixing the ends up somehow so you can plot the graph, and then point to what remains as being “evidence” that the reconstructions are good because they all agree?

In theory, you could simply be ignorant about the facts. But you’ve repeated the pattern too often to conclude that this is anything other than intentional prevarication.

DeepClimate has already put the lie to this particular canard you are attempting to foist on Intersection readers.

Folks, please see the following posts:
http://deepclimate.org/2010/06/29/revisiting-tar-figure-2-21-part-1-another-false-claim-from-steve-mcintyre/
http://deepclimate.org/2010/05/14/how-to-be-a-climate-science-auditor-part-2-the-forgotten-climategate-emails/

So “Nullus” is caught yet again making libelous claims which he almost certainly knows to be false.

Why has he not been permanently banned from the site?

There are actually three figures involved – I’m surprised you didn’t know that – and the “trick” is not simply a matter of missing data.

The basic problem here is the question of what the graph is supposed to show – is it supposed to show the best reconstruction of past temperatures available, or is it supposed to present the evidence/proof for those past temperatures being lower than at present and the current warming “unprecedented”. If you take the former interpretation, the graph is arguably truthful, although it skimps badly on explaining the uncertainties. If you try to interpret it as the latter, which of course many of the pro-AGW polemicists have, then it is grossly dishonest; it seeks to hide good reasons to doubt the validity of the reconstruction method.

The issue is that it isn’t known whether the reconstruction method they use actually reconstructs temperatures – there are lots of factors affecting tree growth, and a relatively small sample of trees to look at. What they do is look at lots of trees, for which the data wiggles up and down, and they pick out those trees where the wiggles match the temperature in the early 20th century and they call them “temperature sensitive”. They then perform a weighted average of these trees over their entire history to reconstruct temperature.

As a precaution against spurious correlation, they check the predictions of this reconstruction against the late 20th century, when they also have records, but the statistical tests unfortunately show no correlation between the reconstruction and the actual temperature, and indeed a number of them descend dramatically at just the time when the temperature was rising. The reconstruction appears to show that the temperature after about 1960 was actually falling! This is called the “divergence problem”.

As a result of this, they have drawn the conclusion that the trees lose their temperature sensitivity after about 1960, probably due to something anthropogenic, but since man only started really affecting things in the later part of the record, the early part is fine. The rapid descent of reconstructed “temperature” is spurious, and needs to be eliminated from the temperature record.

So they cut off the post 1960 data, as not representing temperature. But they have an additional problem because the data is smoothed with a 30-40 year smoothing window, to get a graph that’s easy for the eye to interpret. And with a centred smooth, you have to stop 15-20 years short of the end because you run out of data. This would of course eliminate most of the period of interest.

So what they did was first to chop off the post 1960 data, then they spliced on the instrumental temperature record, then they performed the smoothing up to modern times, and then they chopped it off again at 1960. Because of the way the smoothing works, the last part of the data is a weighted combination of actual tree ring data, and thermometer data from the future. The result is a nice up-tick that fits nicely with the desired picture, instead of a potentially confusing anomaly.

If you accept their explanation that the divergence is due to some unknown and so far undemonstrated anthropogenic influence, and believe the “temperature sensitive” trees really are measuring temperature, then the procedure gives what might be considered the most accurate available reconstruction.

If, on the other hand, you suspect that tree rings are influenced by too many other factors, don’t measure temperature, and the collection of those trees that happen to fit during the calibration period is statistically invalid – and that the near total lack of correlation between the reconstruction and the temperature outside the period of this selection is strong evidence of this, then the cutting-splicing-smoothing-and-cutting-again process is tantamount to simply hiding all the experimental outcomes that disagree with your hypothesis.

Obviously, that’s not a scientifically valid process.

But these graphs are not in the scientific literature, but in the advice to policy makers, and as such it may be argued that they are trying to present conclusions, not evidence. So long as you are clear and consistent about not claiming those spaghetti graphs as evidence of AGW, and pointing it out when others make that mistake, then you could indeed claim some limited vindication here.

Sadly, many on the pro-AGW side have not been so clear and consistent, and it is to these people that the sceptics’ criticisms are addressed.

You are approaching this issue from an entirely anti-evidentiary perspective, focusing only on personalities and the smearing thereof and complaining for complaints’ own sake.