Saturday, January 01, 2011

Only 0.73% of climate scientists think that humans are affecting the climate!!1!

Polymath Andrew Bolt helpfully points to an article by Dennis Ambler demolishing the belief that there's any consensus (how the deniers detest that word, even as they promote petitions to prove an anti-consensus) that the world is warming. In fact, only "0.73% of climate scientists think that humans are affecting the climate".

The article, published by the right wing SPPI, disputes the truth of Examining the Scientific Consensus on Climate Change (Doran, P.T., & Zimmerman, M.K. 2009. Examining the scientific consensus on climate change. EOS 90(3): 21-22.).

Doran and Zimmerman received 3146 responses to a survey asking Earth scientists various questions, including whether they thought temperatures had risen, fallen or stayed the same; and whether they thought humans were contributing to changing temperatures.

What they found was that the more active the scientists were in publishing, and the greater their specialisation in climate science, they more likely they were to consider that humans had caused temperatures to rise (EoR's emphasis):

Results show that overall, 90% of participants answered “risen” to question 1 and 82% answered yes to question 2. In general, as the level of active research and specialization in climate science increases, so does agreement with the two primary questions (Figure 1). In our survey, the most specialized and knowledgeable respondents (with regard to climate change) are those who listed climate science as their area of expertise and who also have published more than 50% of their recent peer-reviewed papers on the subject of climate change (79 individuals in total). Of these specialists, 96.2% (76 of 79) answered “risen” to question 1 and 97.4% (75 of 77) answered yes to question 2.

After various marginal arguments, the contrarian article comes to its damning point (author's emphasis):

It is disingenuous to now use the “climate scientists” as a new population sample size. The response figure of 3,146 is the figure against which the 75 out of 77 should be compared and in this case we get not 97% but just 2.38%.

That's right: the responses of all the other scientists are magically reset by Ambler to a dissenting view, even though the Doran and Zimmerman paper clearly show that 82% believe humans are increasing temperatures. Now that's disingenuous!

Denialism: when the facts don't fit, make your own.

But it gets even better. Ambler's amazing statistical insight enables him to know that a sample doesn't extrapolate to a population. If someone didn't respond, then obviously they don't believe in human caused warming. Thus you can take the non-responders to the survey as well in order to twist your statistics (author's emphasis again).

The original number contacted was 10,157 and of those, 69% decided they didn’t want any part of it, but they were the original target population. When the figure of 75 believers is set against that number, we get a mere 0.73% of the scientists they contacted who agreed with their loaded questions.

Ambler concludes:

What a gross travesty of the truth, and such appalling reporting, but these are the messages fed to acquiescent politicians who do not bother to check the facts, and criticise those who do. How low has science sunk, that scientists will dispense this sort of disinformation to promote their own agenda?

He's directing his vitriol at climate scientists when, in reality, it describes his own article exactly.

Of course, he probably doesn't care how bad his mathematics is, he just wants to have that "Only 0.73% of climate scientists think that humans are affecting the climate" quote sent around the denialosphere as a meme, to be uncritically picked up by the numerically illiterate. Which Andrew Bolt dutifully has done (and why EoR keeps quoting it as well, in the hope that some people searching for it might actually find this post instead and realise how wrong the claim is).

SPPI mathematics primer


  1. What strikes me about climate change deniers is their insistence that what ever humans do cannot have an affect on the world. Thus CO2 created by humans doesn't count because it was not produced naturally.

  2. EoR.

    Kudos for a nice summary. I note that others have also picked up on Bolt's idiocy in repeating Ambler's nonsense, but you deserve acknowledgment for a succint round-up!

    Bernard J.


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