Peer-review's MySpace problem

Fun with paleoclimatologist cliques and hockey sticks

Published August 31, 2006 5:40PM (EDT)

What do social networks and hockey sticks have in common? Answer: they've been dragged, kicking and screaming, into the political fight over global warming. And if you want to see what happens when scientists get mad, read on.

Even casual followers of climate science are likely to have heard of the "hockey stick." The term refers to a graphical representation of global temperature rise over time. For hundreds of years, temperatures remain pretty much the same, and then suddenly skyrocket upwards. In the eight years since paleoclimatologist Michael Mann first presented data supporting a hockey stick interpretation of rising temperatures over the last millenium, the validity or lack thereof of his interpretation of the data has been the source of much light and heat. For a complete summary of the story, this Wikipedia page is pretty good.

RealClimate, a blog closely affiliated with Mann, points us today to the latest twists and turns in the saga. In July, the House Energy and Commerce Committee held two hearings looking into the "hockey stick" and a study now referred to as the "Wegman report," an independent reexamination of Mann et al's data commissioned by committee chair Republican Joe Barton.

Barton is the congressman who outraged mainstream scientists last year when he demanded that Mann and his colleagues reveal all sources of their funding, as well as turn over all their data, software, and related computer files to his comitteee. In a surprise to absolutely no one, the Wegman report went to great lengths to poke holes in Mann's conclusions.

The most original part of the Wegman report was its use of "social network" analysis to undermine the fact that the vast majority of paleoclimatologists support Mann's research. According to the report, the field of paleoclimatology is small and cosy, and virtually everyone in it is connected with Mann, either as a co-author of a paper with him, or as a co-author with one of his co-authors. Anyone who has spent time following links on MySpace or Friendster will grasp the underlying theory, and the Wegman report is full of neat diagrams tracing the relationships. So never mind that Mann's work has been well peer-reviewed. His peers are all his pals, and they're just sticking together. "Our findings from this analysis suggest that authors in the area of paleoclimate studies are closely connected and thus 'independent studies' may not be as independent as they might appear on the surface."

Of lesser interest, but more fun, was the report's slam against blogs "...Much of the discussion on the 'hockey stick' issue has taken place on competing Web blogs. Our committee believes that Web blogs are not an appropriate way to conduct science and thus the blogs give credence to the fact that these global warming issues have migrated from the realm of rational scientific discourse."

Web logs like RealClimate are of course fantastic at ripping apart politically motivated hack jobs like the Wegman report. So maybe that's why Wegman et al would rather they disappear. But heck, let's concede the point -- blogs aren't the place for determining scientific truth. That honor, most scientists would argue, belongs to peer-reviewed journal articles!

Which, by the way, the Wegman report isn't.

But none of this is the fun stuff. RealClimate points to some documents that Mann filed in response to questions asked at the hearings. One of the documents is a transcript of e-mail messages sent to Wegman, a statistician at George Mason University, by retired Stanford physics professor David Ritson, asking for more information on how Wegman generated his own statistical data.

What's good for the goose should be good for the gander, right? The Wegman report said some rather unkind things about the supposed lack of openness with which Mann and his colleages conduct their business, ("we judge that the sharing of research materials, data and results was haphazardly and grudgingly done.")

I won't even pretend to understand what Ritson is getting at when he initially asks, among other things, "Did you otherwise follow M&M using short-span normalization and 70 member Monte Carlo generated ensembles?" But I can sure hear his growing annoyance when Wegman refuses to answer his e-mails.

"Surely you realized that the proxies combine the signal components on which is superimposed the noise? I find it hard to believe that you would take data with obvious trends, would then directly evaluate ACFs without removing the trends, and then finally assume you had obtained results for the proxy specific noise!... Obviously the information requested below is essential for replication and evaluation of your committee's results. I trust you will provide it in timely fashion."

But still no answer! Ritson's final e-mail would put the fear of God into the heart of any quivering undergraduate.

"I understand that people are away or pursuing other interests over the summer. However minimal professional courtesy would generally have ensured a reply as to when you people would provide the requested information. If I do not receive a reply in the next days I can only presume that the requested information will not be supplied. Frankly such an outcome would be quite unprecedented over my long scientific career."

Is there anything better than the smell of scientific e-mail napalm in the morning? We look forward to the next installment.

By Andrew Leonard

Andrew Leonard is a staff writer at Salon. On Twitter, @koxinga21.

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