Chait Stains: Chait vs Hayward, Powerline

Having seen the original Hayward 97% piece at the time, I thought it pretty formidable.  I’m not surprised Chait and some would be spurred to rebut it.

http://nymag.com/daily/intelligencer/2014/05/next-step-in-right-wing-climate-skepticism.html

http://www.powerlineblog.com/archives/2014/05/breaking-the-97-percent-climate-consensus-canard.php

Note, Chait is (thankfully…) NOT using the Hayward article as demonstration of denier ‘ignorance’.  See Chait’s last paragraph:

“It’s a topic of serious debate in American politics because one of the two major parties is controlled by a movement that resorts to bizarre, paranoid explanations for facts that complicate its ideological priors.

So he’s describing this conflict as not a battle between smart and dumb, but something else.  And while I don’t agree there, Chait is certainly fairer and seriouser for couching it this way.

That’s merely a recurring theme I like to broach here though, and not an important point today.

The argument at hand is whether ‘97%’ is a scientifically meaningful number (The Chait / liberal perspective) or rather a impressive sounding but simplistic and dishonest talking point used to groom the acquiescence of a low info constituency (the Hayward / denier position).

Hayward argues that as a matter of math / method, you can never get to 97% affirming consensus based on what actually is counted.  The data set is a collection of 11000 or so papers and abstracts classified topically as related to ‘climate change’  MOST (2/3) of those do not do not take a position on Human AGW.  The rest do, say 3500.  97% percent of those express affirmation of human AGW.

Now the case can probably be made that 97% of 3500 is impressive enough in itself (Hayward argues it would not be impressive given institutional bias…).  But that’s not what is asserted.  Cook and the scientists insist that the dataset is all 11000 papers classified topically as relating to climate change.  When you perform the math this way (which seems to be the obvious way) ‘consensus’ on AGW is about 33%.

How do you get to 97% of 11000 when what you’ve actually counted shows 33% of 11000?  Cook and the scientists take 7000 papers that don’t take a position on AGW and claim that they affirm.

Hayward doesn’t say that 33% is the right number, but he does call bull on the idea that you can count 7000 papers that take no position as affirming.  Ergo, the ‘97%’ derived from this is fraudulent and dishonest.  Chait claims the opposite, and supports Cooks method:

“The papers that did not take a position on AGW were measuring some aspect of climate change without weighing in on its causes. A scientist can measure the melting of a particular glacier without discussing the increase in greenhouse gasses that has contributed to that melting. Likewise, one can write up a finding on Neanderthal bones without endorsing the Theory of Evolution, or calculate a rocket’s speed without explicitly endorsing the Theory of Gravity.  […….]  The papers that take no position on AGW are failing to take a position because it’s not a topic of serious debate among the climate science field. “

I’ll go on to afford Chait’s observation it’s due as a quality semantic argument.  But actually, I don’t think he’s right.  There’s no good methodological reason to assume say that a paper reporting the measurement of glacial melt affirms greenhouse gas / AGW as the causation unless the paper author instructs that this is a proper assumption.

Regardless, in this vein Chait and Cook assert that the 7000 of this type dealing with climate but omitting explicit affirmation of AGW can be tallied within the 97% consensus by virtue of their topicality alone.  IE, they have a climate change reference classification (which is probably somewhat broadly applied to papers), thus they must support the consensus position.

This has the appearance of another extraordinary logical leap, but understanding the trend in scientific thought as we do it very well might be more true than its not (but I think 97% is way too high a number…).  In any event it’s also not much more than an assertion, and it’s not ‘method’.  It’s intuition, it’s Kentucky Windage, this from the crowd that insists it has the weight of scientific measurement arguing in their favor in all cases.

That’s the point that Hayward makes.  Not that there’s no AGW, not that the trends in scientific thought aren’t what they are, but that ‘97%’ is a completely tarted up figure that’s taken on a life of its own in narrative and trope, and is dishonestly misused by liberals and the environmental movement.   I don’t see how anyone argues otherwise without reverting to a semantic observation that is in fact inferior to a proper statistical evaluation of the papers.

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