Have just finished reading A.W. Montford’s (alias Bishop Hill) The Hockey Stick Illusion. Although I thought it excellent, and agree with the reviews (e.g. Air Vent), I thought I would look for contrary opinions, to allow me to compare and contrast the different sides. It just so happens that Tamino has posted a critical review at Real Climate blog on July 22nd. Bishop Hill has responded.
In the spirit of allowing you to make up your own mind, let me present one aspect, which does not need a scientific background to evaluate.
Tamino claims that McIntyre rejects Gaspé because
“This particular series doesn’t extend all the way back to the year 1400, it doesn’t start until 1404, so MBH98 had extended the series back four years by persistence — taking the earliest value and repeating it for the preceding four years. This is not at all an unusual practice, and — let’s face facts folks — extending 4 years out of a nearly 600-year record on one out of 22 proxies isn’t going to change things much.”
I would agree with Tamino, if that was the only problem with Gaspé. But other problems Montford recounts.
- It had the biggest hockey stick of any of the 112 series. 1975 was 3.05 standard deviations from the series mean. Only 12 others had any sort of hockey stick shape. (p.75)
- It was included twice in the proxies – once as part of the North American PC series and once on its own. (p.140).
- It did start in 1404, but until 1421 relied on a single tree, and two up to 1447. The original authors “had not used the early portion of the series at all in their own reconstruction”, but Mann had. (p165.)
- Mann’s own claim for its’ inclusion was that the study represented the northern treeline. But Gaspé was well south of the treeline. As a sensitivity analysis, McIntyre replaced Gaspé with the Sheenjek River Series in Mid-Alaska. It was further north and had more trees. When this was replaced, the medieval warm period re-appeared. (p.166).*
- McIntyre showed “that you could only get rid of the Medieval Warm Period by using the Gaspé series twice and by including the unreliable early portion, and by extending this highly dubious data back to the start of the fifteenth century.”
- An updated study was done taking the data to 1991, instead of 1982. There was nothing like the same growth spurt in recent times. The data went unpublished, and the author claiming to have lost the location. So the results could not be independently replicated. (p.174).
- Montford says in reply to Tamino
“The observation that “McIntyre argued that the entire Gaspe series should be eliminated because it didn’t extend all the way back to 1400” is wrong. MBH had its steps starting at 50-year intervals. Gaspe should therefore have been in the 1450 step not the 1400 one.”
From my simple view, the criticism of the Gaspé proxy series is multilayered. It was used inappropriately; there was a better proxy available (or an update); it was clearly an outlier; and was used twice.
Finally, Steve McIntyre has already criticised Tamino on Gaspé here. McIntyre makes the additional point
“The Gaspé series is a cedar chronology. There is no botanical evidence that cedars respond linearly to warmer temperatures. World experts on cedar are located at the University of Guelph, Ross McKitrick’s university. Ross and I had lengthy discussions with these cedar experts about this chronology – they said that cedars like cool and moist climate.”
* Gaspé is around 49o North (same as Paris), Sheenjek River 65o North. (same as Iceland).
ManicBeancounter 
john
/ 18/11/2010Just in case you guys still have wonderings about if tamino is grant foster, well :-
http://www.citizensky.org/teams/mira-fourier-coefficient-team/what-can-i-do-getting-started-mfct
nuff said.
He’s always struck me as more of a mathematician than a scientist, as in models seem to get tweaked so data fits the preferred theory via mathematical routes, rather than models being set up, predictions made and then tested, and bits dismissed or strengthened depending on the results of the test. But that’s mostly personal opinion.
Not entirely sure what this blog is all about, smells a little as if it might be a redneck site denying global warming from the 2008 stuff, but I’ve been wrong before.
Well, the warming is probably evident enough, and probably going to have affects with climate patterns shifting in season and geography, but how long term it is, where it came from, what’s causing it, and why it should be any different from other times it has happened, and if it is long term or a passing blip, who knows? Certainly it will affect the lives of many, because there are more of us nowadays.
But if it is being supported by slight of hand statistics in the face of entrenched denialists, well, that does more harm than nonharm.
But likely the banking systems will have killed us all off well before we need to worry about it.
manicbeancounter
/ 22/11/2010John,
The hockey stick is not just a slight of hand here and there. It fails on a number of levels – data selection, statistical methods and significance and statistical biases.
The purpose of this posting was to compare and contrast two sides to help towards a more balanced judgement.
In terms of the global warming science and policy as a whole, I believe that to enact policy a case needs to be made that there is a reasonable expectation that post policy enactment the planet & humanity will be in a better situation that if nothing was done. The Stern Review managed to achieve this only by taking an extreme view of the likelihood and extent of the warming; overstating the effectiveness of the policy (a carbon tax);understating the costs of the policy; assuming global adherence; AND assuming that the policy implementation is 100% effective.
Anyone could accept the argument that we are heading for a climate catastrophe and still reject the policy in theory. Further, even if the policy in theory is correct, practically we doing little good and much harm by some of the policies. In particular, ethanol production has lead to the cutting down of rainforests and hurt the world’s poor by more than doubling the world’s food prices.
Overall, there are two analogies that may be of help in illuminating my approach.
1. A minimum expectation of visiting a doctor should be for the patient to be better after treatment than before. That means reasonably accurate diagnosis of both the problem and the seriousness. It means balancing the side-effects and the pain of treatment with the positive effects of treatment. In other words, I would allow for imcompetant treatment of a life-threatenting disease that leaves a patient partly paralysed, when a full recovery would be possible.
2. In a criminal court (in the USA and UK)the prosecution must prove its case beyond reasonable doubt. For global warming policy, I would lower the barrier to making a case for the balance of evidence.
The case is yet to be made in totality. The IPCC are just making the case for the prosecution, and sitting as judge as to what is admissable as evidence. They go even further, as a Judge follows rules laid down by statute or precedence. The IPCC decides the rules of admissability into evidence as well.