Thanks to Mr. Revkin's intrepid reporting, we now know that there is a bit of a schism afflicting researchers looking at methane release from the East Siberian Arctic Shelf (ESAS). After reporting on the permafrost model presented by Dmitrenko at the recent AGU meeting (a model that suggests methane releases in the Arctic are not going to markedly accelerate with climate change), Revkin relates:
Semiletov is finally in touch with me (he'd gone on vacation right after AGU) and you'll hear more on his work soon. He's very critical of Dmitrenko. This kind of back-and-forthing is the process of science in action.And indeed it is. And both of these authors have many peer-reviewed climate studies to their name. They are both respectable professionals, and only time will tell who has a better sense of what is happening on the ESAS. I was interested, though, in how they compared to one another in terms of their stature in this field, so I did a little research.
There is no completely reliable and objective way to gauge the impact of a particular researcher in their field, but a commonly used rule of thumb is to look at the number of times their publications have been cited. Once a scientist crosses the great divide of peer-reviewed publication that separates him or her from a Monckton or a Glenn Beck, the next test of relevance is whether or not their work is useful to others in the field; whether it is considered to be work that needs to be addressed or built upon. Science that doesn't stand the test of time gets superseded or just ignored.
Citations, then, are a way to assess, within the scientific community, what Samuel Johnson called the only objective measure of greatness "length and duration of esteem."
One quick example of how this works. Steig (2009) analyzed temperature trends in Antarctica. A "skeptic," Ryan O'Donnell, with assistance from Steig, turned his critique of Steig (2009) into something that successfully navigated peer review -- O'Donnell (2010). Climate Audit then triumphantly proclaimed "O'Donnell et al 2010 Refutes Steig et al 2009." Watts gloated similarly.
With both publications in print for more than a year, let's see how they're doing:
Improved methods for PCA-based reconstructions: case study using the Steig et al. 2009 Antarctic temperature reconstruction (O'Donnell et al, 2010). Cited by 2.
"Warming of the Antarctic ice-sheet surface since the 1957 International Geophysical Year" (Steig et al, 2009). Cited by 163.So that's basically how it works. Better science tends to get more citations. So with that in mind, I searched Google Scholar for "Semiletov and methane," and "Dimitrenko and methane," and took the first five articles I could find:
Dimitrenko and methane
IA Dmitrenko, SA Kirillov, LB Tremblay… - Journal of Geophysical …, 2010 - agu.org
Cited by 8.
…, JA Hoelemann, I Dmitrenko… - SPECIAL PAPERS- …, 2007 - books.google.com
Cited by 2.
C Schultz - Eos, Transactions American Geophysical Union, 2011 - agu.org
This is a summary of the first paper. I did it again! But there's nothing else to plug in here. No citations.
J Hoelemann, M Makhotin, C Wegner, I Dmitrenko… - 2008 - utsa.edu
Dmitrenko has a total of ten citations for these papers. I felt a little bad about this, so I looked into the matter some more, and found, based on his publications listed at the International Arctic Research Center, that he is more of a water-and-wind guy, and less of a permafrost-and-methane guy (nothing wrong with that). So I tried again with the publications listed here:
Dmitrenko, I, Kirillov S, Eicken H, Markova N. 2005. Wind-driven summer surface hydrography of the eastern Siberian Shelf. Geophysical Research Letters. 32:L14613.
Cited by 13.
Dmitrenko, I, Holemann J, Kirillov S, Berezovskaya S, Ivanova D, Eicken H, Kassens H. 2006. Sea ice impact on the periodical shallow water dynamics in the Laptev Sea (Siberian Arctic). Proceedings of the 16th IAHR International Symposium on Ice at Dunedin, New Zealand. :375-381.
Cited by 2.
Dmitrenko, I, Kirillov S, Ivanov VV, Woodgate R. 2008. Mesoscale Atlantic water eddy off the Laptev Sea continental slope carries the signature of upstream interaction. Journal of Geophysical Research. 113:C07005.
Cited by 5.
Dmitrenko, I, Tyshko K, Kirillov S, Hölemann J, Eicken H, Kassens H. 2005. Impact of flaw polynas on the hydrography of the Laptev Sea. Global and Planetary Change. 48:9-27.
Could not find with Google Scholar.
Dmitrenko, I, Polyakov IV, Kirillov S, Timokhov L, Simmons HL, Ivanov VV, Walsh D. 2006. Seasonal Variability of Atlantic Water on the Continental Slope of the Laptev Sea during 2002-2004. Earth and Planetary Science Letters. 244:735-743.
Cited by 11.
A total of 31 citations, or an average of six per publication (possibly depressed a bit by my inability to find citations for the fourth paper.)
Semiletov and methane
SA Zimov, YV Voropaev, IP Semiletov, SP Davidov… - Science, 1997 - sciencemag.org
Cited by 116.
[PDF] from instrument.com.cnN Shakhova, I Semiletov, A Salyuk, V Yusupov… - Science, 2010 - sciencemag.org
Cited by 55.
Cited by 36.
…, I Semiletov - Journal of Marine Systems, 2007 - Elsevier
Cited by 19.
Cited by 11.
Total citations: 227.
Semiletov's least cited paper is cited almost as many times (11) as Dmitrenko's most cited (13). He has more than seven times as many citations. Also, interestingly, he's clearly something of a specialist in this area; finding five papers about Arctic methane by Semiletov was no trouble at all. Dmitrenko has expertise in the relevant fields of hydrology and the Arctic, but he seems to be something of a methane newbie; only the first paper, which Revkin references, from October 2011, is about methane emissions.
Dmitrenko is a serious scientist; his work should be and will be judged on its merits. Nothing against him. But taking a quick look at their respective records, Dmitrenko is a strange choice for a debunker of Semiletov's concerns. First, basic weight-class stuff:
1. Dmitrenko's top papers have been cited a few dozen times; Semiletov has hundreds of citations.
2. Semiletov has been studying methane emissions from waterlogged permafrost for at least 15 years; Dmitrenko published his first paper on the subject three months ago.
On the type of studies:
3. Dmitrenko's is a permafrost modelling study; Semiletov recently returned with direct observations from the ESAS.
Final verdict: ADVANTAGE SEMILETOV for greater experience, and longer record, more respect from peers, and recent direct observations of the phenomenon in question. I award bonus points because the established methane researcher, with a longer record and more citations, would be the one we would expect would be downplaying recent changes and be disposed to assert continuity in the face of excitable newcomers to the field. If the old man is worried, well, it puts me in mind of the old joke shirt: