EDITOR’S NOTE: What follows is an installment of an occasional blog-extension series. When threads get too long for The Corner, NRO’s main group blog, we take them “Out of The Corner.”
I had a friendly conversation yesterday with Curt Davis, the University of Missouri-Columbia scientist whose study on Antarctic ice I have written about. Think Progress contacted Davis and quoted him as saying that I’d made a mathematical error in discussing his work, and that I’d misrepresented him “just like CEI [the Competitive Enterprise Institute] has.” Let me address those claims in turn.
To explain the math, I must recap what Davis’s study did. Using satellites, Davis measured changes in the elevation of about 70 percent of the interior of the Antarctic ice sheet. He found that about 7.3 million square kilometers in the interior of the East Antarctic ice sheet were rising because of greater snowfall. At the same time, 1.2 million square kilometers in the interior of the West Antarctic ice sheet were losing elevation. Davis explains that this decline in the west was mainly the result of coastal ice loss: When ice flows into the sea, it causes the interior to sink with it. Davis reports that the entire study area of 8.5 million square kilometers thickened at an average of 1.4 centimeters per year.
What I did was take that number–a 1.4 centimeter rise over 8.5 million square kilometers–and try to estimate the effect it would have on sea levels. I followed the same procedure Davis used to estimate the effect that the elevation changes in east Antarctica had on sea levels. Using the number Davis gives for average surface-snow density, one gets the result that a snowfall-caused 1.4 centimeter rise over the entire study area would lower sea levels by 0.1156 millimeters per year. This number, I noted, is extremely close to Davis’s conclusion that the East Antarctic snow buildup was equivalent to 0.12 millimeters per year of sea-level decline.
The trouble, Davis points out, is that ice is denser than snow. Using snow-density numbers to calculate the change over the entire study area accordingly doesn’t show the whole picture, since the areas that lost elevation did so, to a large degree, because of the outflow of ice on the coasts. When I wrote that the whole study area had experienced an ice gain of 41.7 billion cubic tons (the equivalent of 0.1156 millimeters of sea-level decline), I was, in effect, looking only at the consequences of snow buildup (and not of coastal ice loss). In this, I made an error.
What Think Progress doesn’t tell you is that, in the same article in which I gave those numbers, I explicitly stated that Davis’s study didn’t measure loss of ice along the coasts. Contrary to what Think Progress says, I did not claim that you get a net gain for the entirety of Antarctica when you factor in coastal loss.
This speaks to the broader question of whether I have used Davis’s work “just like CEI has.” Davis’s criticism of CEI is that it cites his study as though it were representative of all of Antarctica. In my NR piece, I mentioned his study within the context of discussing increasing Antarctic snowfall, and I did so to give a sense of the magnitude of this phenomenon. That this mention followed immediately upon my quoting Patrick Michaels as saying that the Antarctic ice sheet has grown may have caused confusion, and if I were writing the article again I would put the matter more clearly.
But two things should be sufficient to establish that I did not deliberately misrepresent Davis’s results. First: Although, for the sake of brevity, my original article did not discuss the precise scope of Davis’s study area, my subsequent comments on his work have stated that it didn’t look at changes in coastal Antarctic ice. Second: In my original article, the mention of Davis’s study was followed immediately by my discussion of a more recent study which did look at coastal ice and found that, over the past three years, the ice sheet as a whole has been losing mass. If I were in the business of omitting facts to mislead readers, that surely would have been one of my chosen omissions.
And that goes to the heart of the matter. From my very first article, I have conceded that current research shows net losses for both Greenland and Antarctica. This shows that my argument–i.e., that what we know about coastal ice loss does not justify coercive and large-scale reductions in greenhouse-gas emission–hinges neither on the question whether Antarctica is presently gaining or losing ice nor on the question whether the net change in Davis’s study area was positive or negative. If it turns out that Patrick Michaels–whom I quoted as saying that the net change in Antarctic ice was positive until recently, and whose comments were the basis of my writing that 2002 was a high-water mark for Antarctic ice–is wrong, the argument against alarmism is scarcely affected. We still would have only three years of data for all of Antarctica, an insufficiently long time to establish the existence of a trend or to indicate an appropriate policy response. We still wouldn’t know the degree to which present patterns of ice melt are caused by human activity. We still wouldn’t know whether future melt will cause sea-level rise to a degree that should worry us. Further research may eventually show that anthropogenic climate forcing has reached dangerous levels, but nothing Think Progress has said in reply to my piece has gone the slightest distance in proving that assertion. Think Progress can continue harping on the Davis study and misrepresenting what I said as long as it wishes. But what it will not do is make a convincing case that cost-benefit analysis justifies its favored policies. It will not do this because no one can.
Apart from its further comments on the Curt Davis study, Think Progress says that I have “bastardiz[ed]” Jim Hansen’s global-warming research. Think Progress’s argument is that Hansen says that “global warming is real,” that it could have “disastrous consequences,” but that “we can reduce [its] impact . . . if we limit carbon dioxide emissions, control air pollution and adopt new technologies.” Think Progress notes these things as though I’d portrayed Hansen as someone unconcerned about the consequences of global warming. I did no such thing. In fact, I emphasized the difference between Hansen and Patrick Michaels (the University of Virginia scientist who is generally unconcerned about global warming).
What I said was that Hansen, like Michaels, has questioned how realistic the IPCC’s climate models are. If you read what he has written, you’ll see this for yourself. “It is apparent that the real world is beginning to deviate from the prototypical IPCC scenario,” he writes; and again, “[T]he IPCC predilection for exaggerated growth rates of population, energy intensity, and pollution calls into question the realism of their results.” He notes that current trends of anthropogenic climate forcings are at the low end of IPCC scenarios. He finds that even if no efforts are made to control carbon-dioxide emissions, atmospheric concentrations of CO2 will remain near the bottom of the IPCC scenarios through 2050.
This matters because Think Progress has relied exclusively on IPCC scenarios to argue that we should be deeply worried about the consequences of global warming. The force of that argument diminishes to the extent that those scenarios are unrealistic. In responding to Think Progress, it is not my obligation to show that Hansen isn’t worried about global warming; he is worried, and he may even turn out to be right. But what he says about the IPCC models undercuts the use to which Think Progress has put them, and gives us less reason, not more, to believe that drastic reductions in greenhouse-gas emissions would bring benefits that justified the costs.
I would add, finally, that although Hansen thinks increases in greenhouse-gas concentrations even at the low end of the IPCC scenarios are dangerous, he is honest enough to note that implementation of the Kyoto Protocol would have but a small effect on global warming. Accordingly, his projections about future CO2 emissions reductions assume that these will be accomplished, to a large extent, through improvements in energy efficiency, technologies for capturing and sequestering atmospheric CO2, and new non-carbon-based energy technologies (such as next-generation nuclear power). In other words, the “call to action” that Think Progress says he issues comprises many solutions other than the draconian CO2 caps so beloved of the Left. The fundamental policy question, as it relates to Kyoto-style CO2 caps, is whether such an approach is the most efficient way to protect ourselves against anthropogenic climate forcing. Hansen may favor such policies as part of a comprehensive strategy, but, in emphasizing the value of other approaches, he gives a much more sophisticated picture than the left-green coalition with its endless repetition of the word “Kyoto” as though it were a mantra against all evil.