Some more on von Storch and Zorita

Oct 31, 2005 – 2:38 PM

A number of people are citing the von Storch and Zorita paper as somehow showing that the erroneous MBH98 method did not "matter". I stated previously that the VZ paper indicated that they had inaccurately replicated the hockey stick algorithm – which made their results irrelevant. I have since had some correspondence with von Storch, who I do not regard as being a member of the Hockey Team and who has always been very civil to us in both correspondence and public comments .

von Storch has clarified some points on the methodology in the VZ paper. However, the correspondence has merely confirmed my previous view that they incorrectly replicated the hockeystick methodology of MBH98. I have attached a short script in R here to illustrate the following discussion. Continue reading →

By Stephen McIntyre | Posted in MBH98, News and Commentary | Comments (8)

Pielke's Challenge

Oct 31, 2005 – 12:59 PM

Roger Pielke notes that the hockey stick debate has been widely discussed and has issued a challenge to Mann and myself to summarize why the hockey stick debate should matter to anyone. A fair question. He characterizes the latest exchanges over realclimate posting policy in very unflattering terms to all parties involved (including myself). While I tend to think of my role in this little scuffle as being righteous, it’s hard to get involved without some diminution in dignity. Here’s Roger. (Archive)

By Stephen McIntyre | Posted in MBH98 | Comments (73)

Volkskrant: The Hockey Team Strikes Back

Oct 29, 2005 – 3:05 PM

Martin van Calmthout (who boo’ed the award to Marcel Crok) has published a long article in today’s Volkskrant in Holland. I have enclosed a somewhat tidied machine-translation from altavista.com; I don’t speak Dutch and don’t vouch for anything. (update: Hans Erren edited a prior version and his version follows). The Dutch version follows the English translation. Continue reading →

By Stephen McIntyre | Posted in News and Commentary | Comments (131)

Is Gavin Schmidt Honest?

Oct 29, 2005 – 8:39 AM

I attempted to post the enclosed post at realclimate yesterday, which was rejected. The post was to a topic, where McKitrick and I were directly criticized, and limited to scientific matters. Continue reading →

By Stephen McIntyre | Posted in News and Commentary | Tagged | Comments (462)

Jones et al [1998]: Variance Adjustment

Oct 28, 2005 – 4:13 PM

The first step in the J98 procedure is the standardization of all series based on 1901-1950 and then taking an average. I’m not a big fan of short-period standard deviations (not just me, but see also Trenberth [1984]). All of these series are at least 300 years long, so there’s no need for 50-year standard deviations. Nonetheless, for replication purposes, this was done. Visually, these seem to match pretty much exactly.

Figure 1. Left – Figure 2 from Jones et al [1998]; right – emulation using reconstructed data set.
Continue reading →

By Stephen McIntyre | Posted in Jones et al 1998, Multiproxy Studies | Comments (10)

Jones et al. [1998]: The Proxies

Oct 28, 2005 – 11:17 AM

Jones et al [1998]] did not archive their proxy set as used. I requested this information from Jones this year and was refused, although he did send me two series (Lenca, Law Dome) not locatable anywhere in a public archive about a year ago. Here is some background on the proxies in Jones et al [1998] – 10 NH series and 7 SH series . I doubt that any of this information will be directly usable in my review of this study which is underway and so I’m posting it up. Continue reading →

By Stephen McIntyre | Posted in Jones et al 1998, Multiproxy Studies | Comments (2)

More on von Storch !!

Oct 26, 2005 – 12:32 PM

It looks like there is a huge cock-up in the von Storch and Zorita Comment, which completely screws up their simulations. We alluded to a defect in their methodology in our Reply, but I didn’t realize just how big a defect it was. Continue reading →

By Stephen McIntyre | Posted in MBH98, News and Commentary | Comments (12)

Jones et al [1998]: Confidence Intervals

Oct 26, 2005 – 8:36 AM

I’m working away at Jones et al [1998]. Here’s an interesting diagram from Jones et al [Science, 2001] , which purports to provide confidence intervals for the J98 reconstruction (blue). There’s (at least) one really strange feature in this diagram. See if you can pick it out.


Original Caption: Fig. 2. (A) Northern Hemisphere surface temperature anomalies (deg C) relative to the 1961-1990 mean (dotted line). Annual mean land and marine temperature from instrumental observations (black, 1856-1999) (5) and estimated by Mann et al. (red, 1000 to 1980) (6, 10) and Crowley and Lowery (orange, 1000-1987) (7). April to September mean temperature from land north of 20N estimated by Briffa et al. (green, 1402-1960) (8) and estimated by re-calibrating (blue, 1000 to 1991) the Jones et al. Northern Hemisphere summer temperature estimate (9, 16). All series have been smoothed with a 30-year Gaussian-weighted filter. (B) Standard errors (SE, deg C) of the temperature reconstructions as in (A), calculated for 30-year smoothed data. The proxy average series (6-10) do not extend to the present because many of the constituent series were sampled as long ago as the early 1980s. Continue reading →

By Stephen McIntyre | Posted in Jones et al 1998, Multiproxy Studies | Tagged , | Comments (29)

New WSJ Article

Oct 25, 2005 – 7:36 PM

New comment by Antonio Regalado of WSJ – reporter not editorial writer – is here.

By Stephen McIntyre | Posted in News and Commentary | Comments (60)

VZ and Huybers Comment and Reply

Oct 25, 2005 – 1:14 PM

The von Storch and Zorita Comment and the Huybers Comment, together with our replies, were published by GRL this week. I previously posted up on VZ here and on Huybers here, here and here and have nothing to add at this time.

Original copies of VZ is here; our Reply is here; Huybers’ comment is here and our Reply here. All rights reserved to AGU and not to reproduced without permission. VZ issued a press statement here.

Both VZ and Huybers agree that the MBH98 PC method is biased towards finding hockey sticks. VZ did not accurately implement the full hockey stick algorithm and this affects their results, so their affirmation of the "Artificial Hockey Stick" is based on only a partial implementation. VZ pointed out that our GRL simulations were in a red noise situation and argued that, in a situation where there was an actual signal, the mining tendency of the algorithm would not "matter". In such a situation, the real signal in effect competes with the mining tendency for the attention of the PC algorithm. With proxies that have a signal content, the signal will win out and even the biased MBH98 algorithm will find the signal; however, if the proxies have a very high noise level, then the MBH98 algorithm will find a hockey stick instead of the signal. The MBH98 proxies do not have the correlation to gridcell temperature hypothesized by VZ and a high noise situation applies.

If there are some "bad apples" i.e. nonclimatic hockey stick series, even 1-2 bad apples can substantially distort the result. Even 1-2 bristlecones in a network of over 50 other sites suffice to produce a seemingly "significant" PC using the MBH method. So it’s even more biased in an environment with bad apples than in a red noise situation.

As to Huybers, there is no reason to think that the correlation PC1 is a magic bullet for extracting a "signal" from the MBH98 proxy mess. It does give more weight to bristlecones – but surely that’s the issue at point. We do not say that the covariance PC1 is a magic bullet, but it’s what you would do if you were implementing a "conventional" analysis based even on Huybers’ statistical references [Presiendorfer and Rencher]. I’ve commented on this at length.

Huybers does not confront the problem of the failed cross-validation R2 statistic; I think that the referees should have required him to deal with this, but they did not. If you’ve got a failed R2 statistic, it’s only a matter of curiosity as to explaining a spurious RE statistic. We had showed how the flawed PC method was intimately related to spurious RE statistics. Huybers criticized our explanation. We modified this explanation slightly implementing further details on MBH98, including the most up-to-date information on the source code. with only slight modifications, we once again showed that spurious RE statistics resulted from simulations (which included the re-scaling step proposed by Huybers.) So our explanation that the RE statistic was spurious stands.

Neither VZ nor Huybers discuss the peculiar association of MBH98 with the bristlecones. Huybers suggests that bristlecones would be good to research "in the future". Give me a break. This should have been done by MBH98 before they published, not after.

There’s nothing in either of these comments that resurrects MBH98 or refutes any of our findings.

By Stephen McIntyre | Posted in MBH98, News and Commentary | Comments (49)