Dec 26 2011
Right before Christmas I finally purchased The Hockey Stick Illusion by A.W. Montford (a.k.a. owner of Bisop Hill blog), and I have to admit it has been both a fascinating read and a worthwhile investment in time. I have been able to accelerate my understanding of the interplay between The Hockey Team, the skeptics (led my McIntyre and McKitrick) and the mountain of email and data made public in Climategates 1 & 2.
I am just now nearing the halfway point after the intense march to, and repercussions from, the 2006 NAS ‘investigation’. I have a much deeper understanding of how the RE and R2 (also denoted as r2) verification debate became so intent. I will not be able to explain in a few lines what Montford did so skillfully in many chapters, but the point of this post is to show how the new Climategate emails uncover a blatant lie by one Michael Mann to the NAS panel. A panel that supposedly was an arm of a Congressional Committee investigating AGW theory and the battle over accuracy and correctness between the two camps.
A synopsis of the topic could be summarized as follows:
- In Mann, Bradley, Hughes 1998 (denoted ‘MBH98’ and source of the infamous Hockey Stick graphic) the claim was made that the connection between modern temps and proxy reconstructions was statistically significant and showed today historically warmer than any period since Medieval times.
- However, as McIntyre began his due diligence audit of the methods and data of MBH98 he noted a few problems, only one of which was how MBH98 relied on the rarely used and unwarranted statistical verification of RE instead of the traditional and more reliable R2 . In fact, most statisticians prefer to check multiple verification tests to prove their work is ‘robust’ and not just random correlations without any meaning. It turned out MBH98 admitted to using R2 as well, but did not report the value (i.e., was the math any good). This seemed very strange.
- After much work McIntyre confirmed Mann had performed the R2 test, as had Amman & Wahl in their 2004 papers trying to confirm Mann’s Stick. But nowhere could he find the true values (or the ones ‘recreated’ by Wahl and Amman).
- When Congress decided to investigate the mess, the NAS jumped in to try and protect the AGW claims and held hearings for Congress. It was at these hearings in 2006 that Mann’s Hockey Stick was shown to be pretty much broken. At that time Mann apparently testified (according to Montford’s book) that he had never computed R2.
Here is the passage from The Hockey Stick Illusion and McIntyre’s blog:
He [McIntyre] explained to the panel how Mann had reported in MBH98 that he had calculated the R2 for the Hockey Stick, but had withheld the fact that the results indicated his reconstruction was unreliable. McIntyre went on to demonstrate how the IPCC had later misrepresented the Hockey Stick as having significant ‘skill’. Having dramatically failed the verification R2 test, the confidence intervals for the Hockey Stick were, in the words of Hegerl, “from floor to ceiling”. In other words, you could have no confidence in the results at all.
This was a very damning set of accusations and one which promised some fireworks when Mann came to speak the following day. In the event though, absolutely nothing happened. John Christy, who was seen as the lone sceptic on the panel, asked Mann about his R2 score. Mann tried to evade the question by denouncing its usage in general, but Christy pressed him further, asking whether he had in fact calculated the figure. Mann’s reply was sharp and to McIntyre, at least, breathtaking:
We didn’t calculate it. That would be silly and incorrect reasoning.
Here is where Micheal Mann committed perjury to hide his mistakes. Mistakes that destroy the Hockey Stick and all claims today we are experiencing unprecedented warm climate conditions.We know his MBH98 stated they computed the numbers. But we also know the Hickey Team was working with Wahl and Amman on supporting Mann with Briffa and others. So what where they saying as this went down?
The truth comes from Eugene Wahl himself in a series of emails with Keith Briffa in June 2006, right after the NAS panel. It spans many emails, but let’s focus on email #5240:
Also, let me know if I can help on the issue of RE vs r^2. I could write a few brief sentences as something for you to look at if you would like. Wahl-Ammann show very clearly that there is objectively demonstrated skill at the low-frequency level of the verification period mean for all the MBH segments, although the earlier MBH segments do have really low r^2 values (indicating very little skill at the interannual level).
A low R2 value means there is no statistical significance. The ‘earlier MBH segments‘ are those reconstructions which compared the modern climate to the Medieval Warm Period (MWP). Thus the claim that the MWP is not as warm as today really had not statistical ‘skill’ (something I would also convey to Mann) – according to am brief moment of honesty by Wahl.
We later find out in Montford’s chronology of events that the Wahl-Amman papers never do support MBH98, and in fact confirm the low R2 values which Mann conveniently hid from scrutiny. All this proves the Hockey Stick is actually a crock of stick.
Mann lied many times to NAS. This is probably the most egregious one, to claim he never knew his claims were statistical garbage. No wonder he ran from McIntyre and McIntrick for so many years. They had caught him red handed, hiding the true math and the true results. And all the so called peer review in the world missed this until M&M stepped up and did the scientific process right.
Shame on all the rest for even pretending their PhDs convey upon them the title of ‘scientist’.