Climate Change
In a 2004 Technology Review article, Muller supported the findings of Stephen McIntyre and Ross McKitrick in which they criticized the research, led by Michael E. Mann, which produced the so-called "hockey stick graph" of global temperatures over the past millennium, on the grounds that it did not do proper principal component analysis (PCA). In the article, Richard Muller stated:
McIntyre and McKitrick obtained part of the program that Mann used, and they found serious problems. Not only does the program not do conventional PCA, but it handles data normalization in a way that can only be described as mistaken.
Now comes the real shocker. This improper normalization procedure tends to emphasize any data that do have the hockey stick shape, and to suppress all data that do not. To demonstrate this effect, McIntyre and McKitrick created some meaningless test data that had, on average, no trends. This method of generating random data is called "Monte Carlo" analysis, after the famous casino, and it is widely used in statistical analysis to test procedures. When McIntyre and McKitrick fed these random data into the Mann procedure, out popped a hockey stick shape!
That discovery hit me like a bombshell, and I suspect it is having the same effect on many others. Suddenly the hockey stick, the poster-child of the global warming community, turns out to be an artifact of poor mathematics. How could it happen?
He went on to state "If you are concerned about global warming (as I am) and think that human-created carbon dioxide may contribute (as I do), then you still should agree that we are much better off having broken the hockey stick. Misinformation can do real harm, because it distorts predictions." Muller's statements were widely quoted on skeptical blogs, and his status as a believer in global warming made his criticism of the "hockey stick" particularly damaging. In an article on the RealClimate blog on various myths about the graph, Mann mentioned Muller's article as parroting the claims of McIntyre and McKitrick.
In October 2011, Muller wrote in an op-ed in the Wall Street Journal, concerning his work with the Berkeley Earth Surface Temperature project:
When we began our study, we felt that skeptics had raised legitimate issues, and we didn't know what we'd find. Our results turned out to be close to those published by prior groups. We think that means that those groups had truly been very careful in their work, despite their inability to convince some skeptics of that. They managed to avoid bias in their data selection, homogenization and other corrections.
Global warming is real. Perhaps our results will help cool this portion of the climate debate. How much of the warming is due to humans and what will be the likely effects? We made no independent assessment of that.
While the BEST project did not delve into the proxy data sets used in the "hockey stick", the importance of the work regarding the modern temperature record is explained on the BEST web site:
Existing data used to show global warming have met with much criticism. The Berkeley Earth project attempts to resolve current criticism of the former temperature analyses by making available an open record to enable rapid response to further criticism and suggestions. Our results include our best estimate for the global temperature change and our estimates of the uncertainties in the record.
On July 28, 2012, he stated, "lobal warming real .... Humans are almost entirely the cause."
Read more about this topic: Richard A. Muller
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