Was There a Third "Mike's Nature Trick" to Hide the Decline? Part 3 - Conspiracies Never Die

WA07 Demonstrating Verification Failure of M&M

This is part 3 of a 3 part series on M&M's accusations of "tricks" on the part of MBH and the hockey stick. Part 1 is here and Part 2 is here.

Stephen McIntyre is reporting another "Nature Trick" on his ClimateAudit blog. The post is from Nov 24, 2023. As I've pointed out before, the MBH98/99 hockey stick have been replicated so many times that it's really old news. In 2007, Wahl and Amman were able to emulate the MBH98/99 hockey stick reconstruction and verify that it was robust to statistical method. But there were some slight differences between the two, and it seems some people won't be happy until they emulate it exactly. 

An "Audit" of MBH98/99

In 2021, Hampus Söderqvist apparently succeeded in reproducing MBH98/99 exactly, but in the process of doing so, he discovered some minor errors from the infilling of grid box temperatures in Jones & Briffa 1992 that affected MBH98/99. There were apparently some clerical errors in proxy lists that were in the supplementary material. Söderqvist found these and documented them on his GitHub site in 2021. Mann acknowledged these on the site maintaining the online data related to MBH98/99. There were two readme files acknowledging this. Here's one :

There appear to have been some minor errors in infilling some grid box temperatures series from the Jones & Briffa (1992) monthly data set in Mann et al (1998) and Mann et al (1999). We thank Hampus Soederqvist... for bringing this to our attention. The correct surface temperature data were used in Caspar Ammann & Eugene Wahl's reproduction of MBH98 and lead to very small differences in overall results. 

They then link to where the Wahl and Amman's data and code can be found. In the second readme file, Hampus Söderqvist says,

I now have a very close emulation of the MBH98 reconstruction. It uses the archived proxy lists, with a few exceptions: For the AD 1400 and AD 1450 steps, the reconstruction is not a linear combination of the archived proxies. The correct proxy lists can be determined by adding available proxies until the reconstruction is in their linear span. It turns out that PCs 3 to 6 of the NOAMER network have been replaced with proxies that were not used in these time steps. For comparison, the follow-up paper "Long-term variability in the El Niño/Southern Oscillation and associated teleconnections" lists the first six PCs (table 1, entries 89?94). There is also an undocumented AD 1650 step with its own set of proxies. It is just the AD 1600 set with some additional proxies. 

They then link to where the emulation can be found. They also link to a second emulation by Wahl and Ammann in 2007. What can we take from this? It would seem that the supplementary information still contained some clerical errors that when fixed made trivial changes to the reconstruction. I can imagine this being annoying for those looking to make a precise emulation of MBH98/99, but they don't affect the overall results. But the fact that this could be accomplished also is good evidence that Mann and his colleagues indeed had disclosed all they needed to disclose - if they hadn't, the errors wouldn't have been findable. Nevertheless, this work cleaning up clerical errors in the supplementary material is valuable, and it's the kind of "audit" that can be productive. You would think this would put some of the controversy related to MBH98/99 to rest. 

But no, that's not how conspiracy theories work.

And the Lies That Follow

McIntyre apparently found out about this a couple years after it was discovered and decided it was worth his time to say that what he's calling "Mann's Other Nature Trick" had been discovered. But rather than discovering any tricks, he decided to rehash some of the old talking points that have been debunked for over a decade. Let's recap a few of these:

1. Did Mann withhold r^2 Results?

McIntyre claims, "the table of verification statistics did not include Mann’s verification r2 results... In 2003, we sought these results, ultimately filing a formal complaint with Nature. But, to its continuing discredit, Nature supported Mann’s withholding of these results. Despite multiple investigations and litigations, Mann has managed to withhold these results for over 25 years." 

Except McIntyre knows that's a lie. Mann was asked about these r^2 statistics in 2005, and I've given his full response elsewhere. Here, I'll just quote the most relevant part. Mann didn't use r^2 because that was the wrong statistic to use. In fact, he said, "the highest possible attainable value of r^2 (i.e., r^2 = 1) may result even from a reconstruction that has no statistical skill at all." Instead, he used RE: "RE is the preferred measure of statistical skill because it takes into account not only whether a reconstruction is 'correlated' with the actual test data, but also whether it can closely reproduce the mean and standard deviation of the test data. If a reconstruction cannot do that, it cannot be considered statistically valid (i.e., useful or meaningful). The linear correlation coefficient (r) is not a sufficient diagnostic of skill, precisely because it cannot measure the ability of a reconstruction to capture changes that occur in either the standard deviation or mean of the series outside the calibration interval."

Now McIntyre is free to have his own opinion on what Mann should have used, but it's a flat out lie that Mann withheld statistical calculations he didn't even use. There is no honest justification for McIntyre to keep this objection alive on his blog other than to create the false impression that Mann was "withholding" stuff.

2. Did Mann say there were 159 series, not 112 series?

McIntyre claims, "At the time, Mann also said that MBH98 had used 159 series, not 112 series. We asked Mann to identify the 159 series. Mann refused." And then, "Ultimately, we filed a Materials Complaint with Nature asking them, inter alia, to (1) require Mann to identify the 159 series actually used in MBH98."

Except McIntyre had already been informed that this was entirely his misreading of the following criticism of MM03. "Mann says that the crux of M&M's error is their use of a Excel dataset with only 112 columns (where each column represents one set of proxy data--tree rings, ice cores, historical temperature data, etc.), when in fact the full paleoclimatic data series requires 159 to be used properly in the analysis behind the Mann, Bradley, and Hughes 1998 paper whose results they're trying to check." This says that the spreadsheet needed to "audit" MBH98 needed to have 159 columns, NOT that there were 159 proxies (or "series"). This appears to have baffled McIntyre. In another post, I quote where he said at the time, "This is something new altogether. Where has it ever been disclosed there were actually 159 proxies behind MBH98?" I don't know if the misreading of this email is deliberate or not, but it seems either way, it's not a misreading he was willing to correct.

The real solution to McIntyre's confusion is a lot more trivial and boring than he wants you to believe. MBH98 employed a stepwise reconstruction with separate columns for sub-intervals of the same proxy. They used intervals for 1400-1980, 1450-1980, 1500-1980, and so on. And this has been in print for years. M&M needed "159 independent time series to represent all indicators required for reconstructions of all possible subintervals, even though the maximum number ever used for a particular sub-interval is 112." MM03 clearly did not follow this procedure, and so by truncating their data table to 112 columns, it was simply impossible for MM03 to audit the MBH98 methodology as they claimed they had. And the consequences for the first 200 years of the reconstruction were severe. MBH estimated that M&M "appear to have eliminated in the range of 100 proxy series used by MBH98 over the interval 1400-1600." In Rutherford et al, they further estimated that by not following MBH98's methodology, M&M eliminated about 70% of the proxy data used by MBH98 prior to 1600, so their analysis "gave rise to spurious warmth during the fifteenth century in their reconstruction, sharply at odds with virtually all other empirical and model-based estimates of hemispheric temperature trends in past centuries."

3. Did Wahl and Amman "reinforce" the M&M work?

McIntyre quotes again what Wegman said in 2006: "It is our understanding that when using the same proxies as and the same methodology as MM, Wahl and Ammann essentially reproduce the MM curves. Thus, far from disproving the MM work, they reinforce the MM work." Really? That's not what I get from Wahl and Amman's paper. They in fact said:

the Mann et al. reconstruction is robust against the proxy-based criticisms addressed. In particular, reconstructed hemispheric temperatures are demonstrated to be largely unaffected by the use or non-use of PCs to summarize proxy evidence from the data-rich North American region. When proxy PCs are employed, neither the time period used to center the data before PC calculation nor the way the PC calculations are performed significantly affects the results, as long as the full extent of the climate information actually in the proxy data is represented by the PC time series.

They further found that M&M's critiques were "without statistical and climatological merit." As I point out in another post, in what possible world does this "reinforce" the work of M&M?

Conclusion

It's hard for me to find a way to look at these kinds of claims from McIntyre and come way from them in such a way that any benefit of the doubt that McIntyre wants to be honest should be given.

1. Perhaps McIntyre wasn't aware that r^2 wasn't the right statistic to use and just assumed that it was being withheld. But it was still his mistake, and it was a mistake that lead M&M filing a baseless complaint to Nature. It also lead to Barton asking for this information from Mann and his colleagues in governmental hearings attempting to restrict their academic freedoms.
2. Perhaps it was honest misreading for McIntyre to confuse 159 columns with proxies to begin with. But it was his misreading, and it was a misreading that lead to him file another needless complaint to Nature. And now some 20 years later, he still won't acknowledge this was his misreading that was the issue.
3. Perhaps its true that McIntyre had no control over what Wegman said about WA07 "reinforcing" his work. But that's not an excuse for using the quote to your advantage when you know it's wrong.

In fact, it looks more like McIntyre can be very careless in his reading of information, and then when he's wrong, he refuses to admit he's wrong. Then it seems that he makes a pest of himself to to those who don't take his view on it. Here he certainly made a pest of himself with Nature twice. Then both directly and indirectly through his influence on Barton and others, he made a pest of himself with Mann, Bradley and Hughes. And the pestering isn't limited to MBH. He attempted to crowd source a campaign to pester CRU with emails with EIR/FOIA requests. Given that CRU has a small staff, this can be a tremendous time burden on them. If you have an unwavering conviction that there's a conspiracy, an unwillingness to accept when you're wrong, and the ability to work systems to your advantage, you can make life miserable for lots of people for no good reason. And if you add to that the ability to gain the ear of those with political power, there's a clear threat to the academic freedoms to those that are just trying to do their research well. This issue was over, by any rational standard, in 2007 with the publication of WA07. Some people just won't let it go.

I've pointed out earlier in these posts on the Hockey Stick that Mann has not always been cordial in response to M&M's requests. Without making excuses for him on that point, the flip side of the coin appears to be that there is ample evidence that his frustration with M&M is understandable, even if Mann's behavior isn't always excusable.