## Friday, October 18, 2019

### Top IPCC's paleoclimatologist agrees that Mann's hockey-stick papers were wrong

Two days ago, Tom Nelson (via Willie Soon) informed us about some juicy revelation:

Note that the tweet also includes a link to a McIntyre audio on Watts' blog.

According to an influential IPCC official, McIntyre and McKitrick were right in their criticism of the papers by Michael Mann et al. – the so-called hockey stick reconstruction of the global mean temperature.

In 2006, she was afraid of revealing her name. But it's different today – she agreed to come out of closet. She is a top French climatologist and an avid tennis player with over 30,000 citations according to the Google Scholar. Wikipedia describes her role in the IPCC as follows:
In October 2015, she was elected co-chair of Working Group 1 (WGI) of the IPCC, which is the group that "examines the physical science basis". [2] She was the co-ordinating lead author of the paleoclimate chapter in the IPCC Fifth Assessment Report (AR6) cycle. [4] Masson-Delmotte is currently leading IPCC's Working Group One's (WGI) activities for the Sixth Assessment Report (AR6) cycle. [7]
She was the lead author of "climatology of the past epochs" of the ongoing IPCC writing process – and she seems to govern the whole Working Group One, i.e. the physical basis of the climate, of the IPCC now!

Sometimes skeptics were described as being "scientists, lots of them" but I often felt that the scientific credentials of some skeptics looked questionable – as if skeptics were some Team B. Of course, it's the other way around if you look closely and if you subtract the purely political manipulation with the field. It's the competent climatologists who are generally skeptical – and their third-class colleagues believe in some kind of urgent climate threats.

McKitrick and McIntyre were not the only critics of the papers by Mann et al. but they were the most prominent ones. They did find many problems – including small problems – with the papers by Mann et al. But the most important finding is, of course, that the hockey-stick character of the resulting graph is a result of a methodologically wrong statistical procedure, one that is guaranteed to produce a hockey stick even if you insert random-walk data as the input.

The 2009 ClimateGate scandal revealed that Mann et al. were almost certainly well aware of the fact that their method isn't right and the construction of the hockey stick graph was a pre-planned deception. A powerful colleague of Mann's proposed to use "Mike's Nature trick" to splice two parts of a graph obtained by different methods – and it is this splicing that creates the illusion that something has substantially changed in the recent century or so.

Note that their papers assumed that we could measure the global mean temperature by thermometers from 1900 or so; but we had to rely on proxies – like tree rings – before 1900. Some proxies are nicely correlated with the temperature, some aren't. To find the good ones – proxies with a high correlation – they simply looked how the proxies agreed with the 20th century thermometer readings.

Because the 20th century thermometers may be largely described as a "persistent warming, by almost 1 °C in total", the "proxies that look good" (proxies that have a high correlation with the thermometer-measured temperature) are more or less those that show a "persistent warming" in the 20th century, too. However, the point that Mann et al. completely neglected – and probably deliberately so – is that some proxies unavoidably show a "persistent warming in the 20th century" (and perhaps even a more detailed agreement with the 20th century graph) by chance.

So the process finds lots of false positives – proxies such as trees that look "good" (because their "proxy for the temperature" is increasing in the 20th century) – but they are no good because the 20th century increase is just a chance. If you assume that all proxies are random walks – none of them measures the temperatures at all – you will unavoidably pick some proxies that looked like temperature in the 20th century.

But by my assumption, they're still random walks so when you average these proxies for the epoch before 1900, you will get a constant function! The average of many independent random walk functions is zero. However, after 1900, by assumption, we got the increasing function seen in the thermometers because that's what the "good" proxies were demanded to emulate. In effect, this procedure splices the thermometer readings after 1900 – the 20th century global warming – with a nearly constant function before 1900. It unavoidably understates the temperature variability before 1900. How big the understatement is depends on the ratio of "proxies that really work" and those that "only look good by chance". This ratio isn't too easy to be measured but the number of "bad proxies that got into the ensemble by chance" is surely high enough e.g. because many trees became proxies although their tree-ring width had the opposite sign of the correlation with the temperature than other trees (which is almost certainly not a real biophysical effect).

Do you get this point? There is no real evidence that the temperature before 1900 was "almost constant" or that the 20th century warming trend was faster than in the trends of the previous centuries. The best reconstructions that avoid Mann's mistake – or deliberate deception – show that the 20th century was unremarkable when it comes to the speed of the temperature change.

Her agreement hopefully means that she understands this point – and probably much more than that.

I find her courage charming – because I think that the hysteria is much more insane now than it was in 2006. Virtually all scholars have turned into pseudointellectual sluts – including my former colleagues – who just help (sometimes with their silence, sometimes more actively) all the unhinged far left lying activists who are waging a holy war to destroy science (and physics in particular, especially quantum mechanics and particle physics), energy industry, and, among many other vital things, the Western civilization in general.

Nowadays, I really do despise most of these people – despicable pseudointellectual prostitutes who won't hesitate to worship [beep beep] or even Greta Thunberg if it helps to fill their wallets – including many people whom I used to like. Their uniform collaborationist attitude makes the approach of the French IPCC lead author even more remarkable.

To protect her, I haven't typed her name in the title – or anywhere in the body of this blog post, using my own keyboard. That should be enough because the alarmist sociopaths are incapable of reading technical articles or even essays like mine, especially the parts beneath the title. But in this world plagued by pandemics of Gretinism, I am still worried about her safety or at least about her job!

It's a question whether her statement would be more helpful in 2006. She might be more influential within the IPCC than she was 13 years ago. However, the whole climate hysteria movement – which was never about the science – has moved away from even pretending that it's revolving around the scientific research. These days, people are overtly pushed into obedience to mentally defective teenagers so the comments by the IPCC lead authors probably no longer matter much.