At Keith Kloor’s a little while back, I tried to reach something of an amicable cease-fire with Roger Pielke, Jr. I decided to set aside his constant attacks on the scientists who blog at RealClimate in the interest of moving the discussion on mitigation options forward.
Stefan Rahmstorf and Dim Coumou published an article in PNAS examining the influence of warming on the likelihood of extreme temp events, notably in the context of the blistering 2010 Russian heat wave. Roger accuses Rahmstorf of cherry-picking his period of analysis, and then uses this accusation to cast aspersions on the integrity of climate science more generally.
Here is another good example why I have come to view parts of the climate science research enterprise with a considerable degree of distrust.
Climate science — or at least some parts of it — seems to have devolved into an effort to generate media coverage and talking points for blogs, at the expense of actually adding to our scientific knowledge of the climate system. The new PNAS paper sure looks like a cherry pick to me.
What’s Roger’s actual complaint with the Rahmstorf and Coumou paper? Roger writes:
Look at the annotated figure above, which originally comes from an EGU poster by Dole et al. (programme here in PDF). It shows surface temperature anomalies in Russia dating back to 1880. I added in the green line which shows the date from which Rahmsdorf and Coumou decided to begin their analysis — 1911, immediately after an extended warm period and at the start of an extended cool period.
Obviously, any examination of statistics will depend upon the data that is included and not included. Why did Rahmsdorf and Coumou start with 1911? A century, 100 years, is a nice round number, but it does not have any privileged scientific meaning. Why did they not report the sensitivity of their results to choice of start date? There may indeed be very good scientific reasons why starting the analysis in 1911 makes the most sense and for the paper to not report the sensitivity of results to the start date. But the authors did not share that information with their readers. Hence, the decision looks arbitrary and to have influenced the results.
Roger obviously didn’t bother to actually read the paper he’s attacking.
If there’s one thing Roger can’t stand, it’s scientists pointing out that man-made global warming is making certain kinds of extreme events worse. If there’s another thing he can’t stand, it’s the scientists who blog at RealClimate. Put them together, and Roger goes off the deep end.
Caught out, Roger is predictably moving the goal posts rather than acknowledging that his attacks were unjustified.
First Roger attacked Rahmstorf and Coumou for ignoring the pre-1911 data. He uses this ostensible sin of omission to smear the larger field. Except of course this is completely false. When this is pointed out, Roger moves the goalposts and claims that Rahmstorf and Coumou didn’t actually look at the 1880-2009 data because they didn’t use a linear trend to look at the 1880-2009 data. [Edited to add: this is an implicit rather than explicit claim by Roger, as we’ll see.] The paper is quite clear about making the case that the data (for 1911 on and for 1880-2009, for synthetic data and actual obs) are better described by a nonlinear trend, and the passage I cited in the original point makes it clear that the 1880-2009 data were analyzed using a nonlinear trend.
Roger then has the chutzpah to claim that Rahmstorf has “confirmed” Roger’s “critique”:
It would be quite shocking indeed if Rahmstorf actually “confirmed” Roger’s critique. But of course he did no such thing. When Roger claims “they did not run the analysis from 1880”, he’s completely wrong (see the above excerpt from the paper). When he claims Rahmstorf has “confirmed” his critique, what Roger really means is that Rahmstorf confirmed that they did not look at the 1880-2009 data using a linear trend– which, again is perfectly clear in the paper itself. So it has gone a bit like this:
Roger: “They didn’t look at the whole record!”
Uh, yes, they did.
Roger: “No, they didn’t perform The Analysis* for the whole record!”
*Valid only for Roger’s definition of “The Analysis”.
Roger has taken a concession that the paper did not do something it never claimed to have done and declared victory. Perhaps at some point he’ll realize that claiming something does not make it so.
Roger has repeatedly made the claim that Stefan Rahmstorf “confirmed” Roger’s critique. Roger’s original critique was that the 1880-1910 were not analyzed by Rahmstorf and Coumou. This original critique is patently false, as the paper shows in the excerpt I posted above.
The basis for Roger claiming that Rahmstorf “confirmed” his critique was Rahmstorf stating that a linear trend was not used in analyzing the 1880-2009, as is clear in the paper.
I let Rahmstorf know that Roger was claiming Rahmstorf confirmed Roger’s critique. Rahmstorf responded:
That is truly bizarre, since what I responded to Pielke (in full) was: “We did not try this for a linear trend 1880-2009. The data are not well described by a linear trend over this period.” As shown in the paper and above, our main conclusion regarding Moscow (the 80% probability) rests on our Monte Carlo simulations using a non-linear trend line, and of course is based on the full data period 1880-2009. Nowhere did we “use 1910-2009 trends as the basis for calculating 1880-2009 exceedence probabilities”, and I can’t think why doing this would make sense. Faced with this kind of libelous distortion I will not answer any further questions from Pielke now or in future. As an aside, our paper was reviewed not only by two climate experts but in addition by two statistics experts coming from other fields. If someone thinks that using a linear trend would have been preferable, that is fine with me – they should do it and publish the result in a journal. I doubt, though, whether after subtracting a linear trend the residual would fulfill the condition of being uncorrelated white noise, an important condition in this analysis.
And on a final note, Pielke actually had the nerve to write this:
You may read the paper differently than I do and you may interpret Rahmstorf’s comments differently than I do — happens all the time on these blogs. In such a situation I propose that the best course of action would be to solicit further information to resolve the dispute. Or, perhaps you’d rather we just make comments about motives and call each other names
This, after he wrote a post impugning the field over an “omission” that existed only in his mind. Unreal.