2009-03-16 Comments on EPA DTS Document/woozle
Carlin's arguments seem to depend on a fairly detailed understanding of climate. He is an economist, so it seems unlikely that he would have this knowledge -- but in the interest of scientific democracy, it's certainly possible to take a look and see what he is claiming.
His thesis seems to be that the greenhouse gas/CO2 hypothesis is broken, and therefore AGW is wrong. He lists 7 objections, any one of which (he claims) refutes the GHG/CO2 theory.
Starting in on his list of of objections:
1. Lack of observed upper tropospheric heating in the tropics (see Section 2.9 for a detailed discussion).
Section 2.9 starts out with the claim that "Computer models based on the theory of GHG/CO2 warming predict that the troposphere in the tropics should warm faster than the surface in response to increasing CO2 concentrations, because that is where the CO2 greenhouse effect operates."
However, he provides no references for this claim. Is it true? There's no way to tell. Since he's not an expert in the field, he must have read it somewhere specific (rather than absorbing it from, say, discussion with colleagues) -- and if this is truly fundamental to AGW theory, then it seems important to show this fact.
Nonetheless, I was able to find a refutation of this point here:
2. Lack of observed constant humidity levels, a very important assumption of all the IPCC models, as CO2 levels have risen (see Section 1.7).
Section 1.7 discusses the implications of two quite recent papers (both 2009, so less than 3 months old when Carlin was writing), but does not seem to explain how such recent work constitutes a clear anomaly in the AGW hypothesis, much less completely damning (as he claims). He presents the work as authoritative -- but AGW certainly does not depend on any such recent work.
A more sensible approach would have been to (re-)present the argument given in those works -- on its own merit -- and then give the papers credit for thinking of it.
Not that it's impossible, but his explanation seems to be more intended as a Chewbacca argument (overwhelm the reader with input until they throw up their hands and "let the Wookiee win") than a sincere objection.
Also: is Theoretical and Applied Climatology (the source of the first of the two articles, Paltridge 2009) a reputable journal? I couldn't find anything about it in Wikipedia. Its official web site appears to be here:
...but the page numbering for 2009 (January is pp 1-221, March is 223-422) is not consistent with the page numbers given in the citation for the article (pp 1434-87).
Strike Two. (A little digging: It seems to be in the October issue, pages 351-359: http://www.springerlink.com/content/m7674162066g/?sortorder=asc&p_o=10 Content currently subscriber-only, so I can't check it out in more detail.)
3. The most reliable sets of global temperature data we have, using satellite microwave sounding units, show no appreciable temperature increases during the critical period 1978-1997, just when the surface station data show a pronounced rise (see Section 2.4). Satellite data after 1998 is also inconsistent with the GHG/CO2/AGW hypothesis.
Section 2.4 does not seem to explain why 1978-1997 is a critical period, nor does it give any sources for the surface temperature data or the satellite data which supposedly contradicts it; his sole source for these claims would seem to be a paper by fellow GW-denialst Don Easterbrook.
The statement about "no appreciable temperature increases... 1978-1997" does not appear to be meaningful; there were a couple of significant swings during that fairly short time period, but the larger data still shows a clear upward trend. See this graph:
The 1998 claim is addressed here:
Strike Three. OUT.
Just glancing through subsequent paragraphs, this claim jumped out at me: "The idea that warming temperatures will cause Greenland to rapidly shed its ice has been greatly diminished by new results indicating little evidence for the operation of such processes."
Somewhat earlier, but more Greenland-specific:
Just on the basis of that statement alone, I would have to presume that this guy is willfully ignorant of what's going on around him, much less the fine details of climate science.