Saturday, July 25, 2009

Watershed: the McLean, de Freitas, and Carter paper

I've been thinking quite a bit about the very recently published McLean, de Freitas, and Carter paper published in the Journal of Geophysical Research. (Put those three names in a Google search and watch the search results explode.) Both the underlying and visible animosity between the climate change obfuscatori (the skeptics) and climate change cognoscenti is on full display on the blogs. The speed at which this paper has gotten out, gotten word, and gotten thoroughly lambasted is astonishing, even in this era of the Internet.

And it's just getting started. I expect the paper to be exhibit 1 (or at least 1A) when the Senate takes up Waxman-Markey. There's a reason I think that. The Inhofe drumbeat has been that "growing numbers of scientists" are "dissenting" or "debunking" or other such malarkey the scientific underpinnings of climate change. (See here, which has "Scientific meetings are now being dominated by a growing number of skeptical scientists.") This paper takes that as far as it can in attempting to cast doubt on the climate influence of anthropogenic CO2; mainly through subtle comments in the Conclusions that are apparenty unmerited (I could also say groundless) by what's actually done in the paper. Over on Tamino's "Open Mind" blog, where the first critical lambasting of the paper was performed, it appears that 1st author John McLean attempted to defend the paper, leading to this final comment in reply from Tamino:

Let's "duke it out" in the peer-reviewed literature, shall we? Expect a comment on your paper to appear soon in JGR. I can hardly wait to see how you'll respond there. [Yeah, neither can I, but...]

... the problem is, what if the paper isn't wrong? I mean, what's wrong about it is not the methodology or the results, but actually those subtle comments in the Conclusions, which Carter amplified in the press releases about the paper -- the press releases which have been gobbled up by the skeptical blogosphere, as well as media sympathetic to the skeptical snake-oil. Can a refutation article be written about subtle comments in the Conclusions when the paper's results (which show a lagging influence on global temperature from the ENSO state of the Pacific Ocean) are probably reasonably accurate? I get a sense from some of what Tamino says:

The fact that the method used in McLean et al. removes all effect of trend from the result isn't the *only* problem with this paper. The methodology greatly inflates the correlation between SOI and global temperature, so much so that it gives a ludicrous estimate of the degree of influence of SOI on global temperature.

that there's enough wrong with the paper to justify the rebuttal article and get it published. But I'm not sure. And if JGR somehow disallows rebuttal articles to the paper, then the paper will end up being a triumph for the skeptics.

On the other hand, if it goes down in flames, it will be a fairly good example of the kind of biased-science-leading-to-biased- (and heavily-hyped) conclusions that is being practiced by a very, very, very, very, very, very, very, very small number of actual practicing scientists who are somewhat qualified to publish in the field of climate science.

All I can say right now is: Fascinating. Pass me the popcorn.


Hank Roberts said...

"... I have spotted one more error that no-one else has commented on so far .... It's not as significant as the one Tamino deals with, but here it is anyway. Paragraph 30 reads as follows:..."

John said...

Tamino seems to have set himself up as some sort of expert in every field of science and talks down to us with somewhat childish demonstrations of the effects of differention in removing trends, as if we should hang on his everyword. There is no question that the paper demonstrates clearly and honestly from the data, all that is claimed for it, and no attempt is made to hide the "trend" which Tamino is so hung up on, being clearly presented in the very first diagram, Fig 1. The statistics have obviously been prepared by a professional statistician and despite all the yelping, every graph presented, using a variety of data, shows a clear correleation between changes in the Southern Oscillation Index and respectable sets of global temperatures. The main point concerning trends, is the obvious sudden jump in both SOI and temperature about 1976 which was not, as far as I am aware, a particularly bad year for the emission of carbon dioxide. If people could just calm down and quietly analyse the paper, check the references, check the data sets and perhaps carry out some other statistical analysis which may confirm or negate the findings in the paper, we could all enjoy a satisfying and enlightening scientific discussion.

Hank Roberts said...

> there is no question

Except for, at least the several scientists Annan links to in the post I mentioned, who have raised several questions

> demonstrates clearly and
> honestly
> all that is claimed for it

But no, it claims far more than it demonstrates. Your statement of faith is touching but citeless.

Brief excerpts from longer discussions by two more scientists Annan pointed to back in July:

"These authors make the completely unsurprising point that that there is a correlation between ENSO indices and global mean temperature – something that has been well known for decades – and then go on to claim that that all trends are explained by this correlation as well...."


"The denialists are now trumpeting a very silly argument that El Nino (a quasiperiodic oscillation with energy in the 2-10 year band) is dominating secular trends in global temperature by an argument that I summarized in seven steps recently.

I would like to start the day with a shorter summary:

1) El Nino dominates interannual variability.
2) Frantic armwaving, accompanied by sciencey-looking charts and graphs.
3) Therefore, warming is predominantly due to El Nino.
4) Therefore, very not the IPCC."

The verification word today is:

Apt enough!

This is just to illustrate the point that "it's a poor memory that only works backward" -- don't rely on strangers on blogs to come along every six months and bring them up to date like this; you have to look for newer information yourself. It's a kindness if you post good sources when you find them.