Isotope schistatope. It's a red herring and unnecessary to see the truth.
actually to recap....
![]()
97% claim exposed / debunked.
http://wattsupwiththat.com/2013/09/0...r-math-errors/
â0.3% climate consensus, not 97.1%â
PRESS RELEASE â September 3rd, 2013
A major peer-reviewed paper by four senior researchers has exposed grave errors in an earlier paper in a new and unknown journal that had claimed a 97.1% scientific consensus that Man had caused at least half the 0.7 Cº global warming since 1950.
A tweet in President Obamaâs name had assumed that the earlier, flawed paper, by John Cook and others, showed 97% endorsement of the notion that climate change is dangerous:
âNinety-seven percent of scientists agree: #climate change is real, man-made and dangerous.â [Emphasis added]
The new paper by the leading climatologist Dr David Legates and his colleagues, published in the respected Science and Education journal, now in its 21st year of publication, reveals that Cook had not considered whether scientists and their published papers had said climate change was âdangerousâ.
The consensus Cook considered was the standard definition: that Man had caused most post-1950 warming. Even on this weaker definition the true consensus among published scientific papers is now demonstrated to be not 97.1%, as Cook had claimed, but only 0.3%.
Only 41 out of the 11,944 published climate papers Cook examined explicitly stated that Man caused most of the warming since 1950. Cook himself had flagged just 64 papers as explicitly supporting that consensus, but 23 of the 64 had not in fact supported it.
Hans von Storch is a german climate scientist who has an unfortunate tendency to portray differences of opinion with other scientists as to just how harmful global warming will be in terms of the other scientists "over selling" the dangers. He, along with Dennis Bray, he has published the most interesting and detailed survey of climate scientist's opinions on climate science.
Unfortunately, the survey has (at least) one major technical flaw. Many of the questions are phrased as "How convinced are you that ...", which choices listed from "not at all convinced" (1) to "very much convinced". Technically, anybody who is a little convinced that the statement is not true, or has no opinion on the matter would be "not at all convinced" under this scheme. Thus, anybody responding "2" or higher at least thinks the statement is more likely true than not. Certainly somebody responding "4", ie, that they are moderately convinced are not epistemically neutral on that issue.
Bray and von Storch, and likely most respondents have interpreted questions with that format as representing a range of opinion from complete disagreement to complete agreement with "4" representing a neutral response. They have done this based on normal conventions in survey responses which tend to over ride strict interpretation of questions. The result is that the survey response is, IMO, biased against agreement on various issues.
Despite this, on the crucial questions, "20. How convinced are you that climate change, whether natural or anthropogenic, is occurring now?", and "21. How convinced are you that most of recent or near future climate change is, or will be, a result of anthropogenic causes?" (both on page 46), climate scientists overwhelmingly support the consensus responses. In the first case, the mean response is 6.4 with a standard deviation of approximately 1, and a total of 93.8% "agreeing", ie, having a response of "5" or higher. In the second case, the mean response is 5.7 (st dev = 1.4), with 83.5% "agreeing".
The discrepancy between the 83.5% figure from Bray and van Storch (2010) and Cook et al 2013 is partly due to the bias discussed above, and partly because they survey different things. Specifically, Cook et al survey the proportion of scientific papers endorsing the consensus while Bray and von Storch directly survey the opinions of scientists. From Anderegg et al, we know that scientists "convinced by the evidence" in favour of the consensus have, on average, published twice as many peer reviewed articles as those who are "unconvinced by the evidence". On that basis alone, even accepting Bray and Von Storch as accurate, we would expect 91% of papers to endorse the consensus. Further, the evidence simply does support the consensus. Consequently those who are less convinced, if accurately reporting the evidence, will less frequently be able to find results that actually endorse their beliefs. There will be a tension between their beliefs, and the evidence that will be reflected in the literature.
Given this, Bray and von Storch (2010) does not rebut, or call into question the results of Cook et al (2013). What it does do, or should do, is put a brake on the misinterpretation of Cook et al as showing that 97% of climate scientists endorse the consensus. Cook et al does not show that, and cannot show that because it is a survey of the literature, not of scientists opinions.