Zonkerbl wrote:Why is "not understanding statistics" considered a valid counter-argument to climate change science?
https://en.wikipedia.org/wiki/Hockey_stick_controversy"More than two dozen reconstructions, using various statistical methods and combinations of proxy records, have supported the broad consensus shown in the original 1998 hockey-stick graph, with variations in how flat the pre-20th century "shaft" appears.[12][13] The 2007 IPCC Fourth Assessment Report cited 14 reconstructions, 10 of which covered 1,000 years or longer, to support its strengthened conclusion that it was likely that Northern Hemisphere temperatures during the 20th century were the highest in at least the past 1,300 years.[14] Over a dozen subsequent reconstructions, including Mann et al. 2008 and PAGES 2k Consortium 2013, have supported these general conclusions."
Your article flatly states that "Expert computer analysts then demonstrated, however, that the methods used to construct this graph were hopelessly flawed. It became the most discredited artefact in scientific history."
This article has zero credibility. They don't even know how to spell "artifact." Go read something else.
The Medieval Warming Period was considered fact and acknowledged as such in all relevant literature up until 1998. The Medieval Warming Period was particularly alarming to those pushing the global warming agenda because it belied the notion that the warming of this past century is unprecedented. As Jay Overpeck, an IPCC participant said in his email to Professor Deming in 2005, "I get the sense that I’m not the only one who would like to deal a mortal blow to the misuse of supposed warm period terms and myths in the literature."
Then, in late 1998, Michael Mann comes forth with a radical new theory using tree ring data and a whole lot of statistical massaging, he made the Medieval Warming Period disappear! Normally, such a dramatic change in conventional understanding would be met with skepticism, requiring years of follow-up research, and confirmation, but not so with Mr. Mann. It took just 12 months for his paper to be thoroughly incorporated and enshrined as fact in the Third Assessment Report of the IPCC in 2000. The Hockey Stick was then revealed in 2001.
Fortunately, Steve McIntyre demanded to see the raw data and the analysis and he and Ross McKitrick dug deep to see what Mann was doing with his statistical manipulations. Here is an example of what they found:
Above are two separate temperature reconstructions running from 1400AD, both use tree rings, one is from California and one is from Arizona. Both were were part of the data used by Mann and included in the Hockey Stick average. The top one shows a temperature up tick at the end in the 20th century like the final Hockey Stick, the other shows a relatively flat temperature for the 20th century. Mann’s statistical trick gives the top series, the one with the desired Hockey Stick shape a weighting in the data that is
390 times that of the bottom series just because it has a Hockey Stick bend at the end. This means that whatever data is fed into Mann’s statistical manipulations is almost bound to produce a Hockey Stick shape whether it is actually in the data or not.
Without Mann's statistical manipulations, the data looked like this:
Eventually a US senate committee of inquiry was set up in 2006 under the chairmanship of
Edward Wegman a highly respected Professor of mathematics and statistics to evaluate the controversy. They concluded:
Our committee believes that the assessments that the decade of the 1990s was the hottest decade in a millennium and that 1998 was the hottest year in a millennium cannot be supported by the MBH98/99 [the technical name of Mann’s original Hockey Stick paper]
Conclusion 1. The politicization of academic scholarly work leads to confusing public debates. Scholarly papers published in peer reviewed journals are considered the archival record of research. There is usually no requirement to archive supplemental material such as code and data. Consequently, the supplementary material for academic work is often poorly documented and archived and is not sufficiently robust to withstand intense public debate. In the present example there was too much reliance on peer review, which seemed not to be sufficiently independent.
Conclusion 2. Sharing of research materials, data, and results is haphazard and often grudgingly done. We were especially struck by Dr. Mann’s insistence that the code he developed was his intellectual property and that he could legally hold it personally without disclosing it to peers. When code and data are not shared and methodology is not fully disclosed, peers do not have the ability to replicate the work and thus independent verification is impossible.
Conclusion 3. As statisticians, we were struck by the isolation of communities such as the paleoclimate community that rely heavily on statistical methods, yet do not seem to be interacting with the mainstream statistical community. The public policy implications of this debate are financially staggering and yet apparently no independent statistical expertise was sought or used.
Conclusion 4. While the paleoclimate reconstruction has gathered much publicity because it reinforces a policy agenda, it does not provide insight and understanding of the physical mechanisms of climate change except to the extent that tree ring, ice cores and such give physical evidence such as the prevalence of green-house gases. What is needed is deeper understanding of the physical mechanisms of climate change.
