Not surprisingly, I am starting to get shelled from the Right because of my recent NRODT cover story on global warming.
The most widely read of these critics is Steven Milloy, an adjunct scholar at Cato and CEI, as well as the publisher of JunkScience. He has written a very long (~2,000 word) attack piece that takes me to task for failing to understand either the science or the politics of the issue. I have read his article carefully, and I am not convinced that he is correct. I suspect, however, that he has raised some reservations that some other conservatives hold as well, so I thought that it would be useful to respond in detail.
You can read his entire article here uninterrupted. I will go through his entire article sequentially, and respond to each specific criticism in this post. In the spirit of Marlo’s classic post on Harry Reid, I will break this into two sections in the interest of length. The first section will be more or less science issues, and the second will be more or less political issues. Milloy’s article will be in regular type, and my comments will be inserted in italics.
What should conservatives do about global warming? Jim Manzi suggests in his June 25 National Review cover story (“Game Plan”) that conservatives embrace junk science and “manage” global climate change so that they can “peel off” 1 percent of the votes from the “opposing coalition” in some future presidential election.
Manzi’s is a recipe for social, political and economic disaster – not just for conservatives, but for everyone, with the possible exception of the back-to-nature socialists among us.
“It is no longer possible, scientifically or politically, to deny that human activities have very likely increased global temperatures…,” intones Manzi, who has apparently spent too much time watching “An Inconvenient Truth.”
It’s clear from his article that he neither understands the science nor the politics of global warming.
So far, it’s rhetoric. Here comes some content…
Manzi says we should believe in global warming because of the “underlying physics.” He writes, “All else equal, the more CO2 molecules we have in the atmosphere, the hotter it gets.”
But both the underlying physics and historical climate data debunk this statement.
Different greenhouse gases absorb different wavelengths of energy emitted by the Earth. The fact that only a limited amount of the Earth’s emitted energy is available for absorption by CO2 and that CO2 has to compete with water vapor and clouds for that energy, results in a crucial (but little publicized) logarithimic relationship between CO2 and temperature – that is, as atmospheric CO2 increases, it absorbs less and less additional energy to produce correspondingly less and less additional warming. At some point, adding more atmospheric CO2 doesn’t significantly change atmospheric temperature.
OK, explicit in Milloy’s discussion is that, exactly as I said in my article, “All else equal, the more CO2 molecules I have in the atmosphere, the hotter it gets.” The reason you can’t get around this is that you have added energy to a vessel – it will get hotter. The whole debate is around how much hotter.
As we’ll see, the “all else equal” part is a very big deal, but let’s start where Milloy starts.
To describe the logarithmic relationship between CO2 and temperature as “little publicized” and act as if he is letting us in on a secret is ludicrous. The fundamental unit of measurement of climate sensitivity is the impact on global temperatures of a doubling of atmospheric concentration of CO2, i.e., the relationship is logarithmic. It is cited on page 12 of the current UN IPCC WG1 Summary for Policymakers. It has been widely analyzed in major scientific papers for many decades. I posted on one such landmark paper from 1975. In fact, it has been the basic unit for measuring temperature sensitivity to CO2 since Arrhenius first postulated the greenhouse effect in 1896. There are thousands of scientific papers that consider the impact of CO2 in explicitly logarithmic terms. Some of the most obvious examples, beyond those previously indicated, include this, this, this, <a href="http://ams.allenpress.com/perlserv/?request=get-abstract&doi=10.1175/1520-0485(1990)0202.0.CO;2″>this and <a href="http://ams.allenpress.com/perlserv/?request=get-abstract&doi=10.1175/1520-0442(1988)0012.0.CO;2″>this. Examples of more popular discussion of the logarithmic nature of climate sensitivity include this, this, this and this. Or this or this. Oh yeah, there’s also this, this and this. Go to Google and enter [doubling “carbon dioxide” temperature], and you can find about a million such examples.
To analogize, consider a window with many shades, each blocking half the incoming light. As successive shades are pulled, the transmitted light is halved and the effect of each shade is diminished. Eventually, there’s no additional effect because previous shades have already absorbed the light to all but a vanishing degree. As more shades won’t block more light, more CO2 won’t cause significantly more warming.
Or we could just do the math. All this means is that if going from 100 to 200 parts-permillion in the atmosphere (ppm) of CO2 causes temperatures to increase X degrees, then to get the same X degree increase in temperature you would have to go from 200 to 400 ppm, then to get another increase of X degrees, you would have to go from 400 to 800 ppm, and so on. Therefore, the statement that “more CO2 won’t cause significantly more warming” is wrong because it begs the question of what is “significant.”
How might this distinction matter, rather than being a word-game? Well, consider a world that has super-linear increases in emissions over time (such as the one we live in) – this might drive roughly constant increases in temperature by time period in spite of the declining marginal impact of each molecule of CO2. Alternatively, there might be some absolute temperature point at which catastrophic climate change occurs, so even if the rate of increase slows, it still might be quite “significant” as we approach that threshold. Just because there is a log relationship doesn’t mean that further emissions become “insignificant” at some ill-defined point, or that we are anywhere near such a point right now.
In fact, there’s been more than enough greenhouse gas in the atmosphere to cause much greater warming than actually occurs since long before humans discovered fire.
I don’t understand this sentence.
From a historical perspective, consider the relationship between carbon dioxide emissions and global temperature for the period 1940-1970. As atmospheric CO2 levels steadily increased during this period, global temperatures decreased, giving rise to the 1970s-era scare of an impending ice age. It’s also clear that, if there has been a relationship between atmospheric CO2 and global temperature since the 1970s, it’s not readily apparent.
This is a type of argument that Milloy uses repeatedly in his piece. He identifies several decades or a geographic region, or the combination of both, for which there is no correlation between CO2 and some relevant outcome that would support the hypothesis that human activity is creating global warming, and acts as if this is a smoking gun that disproves the hypothesis. In technical terms, he is claiming that the hypothesis has failed a falsification test.
This is like saying “Look, I cut way down on fatty foods after the holidays and the level of plaque in my arteries did not noticeably decrease by April, therefore this theorized link between fat intake and arteriosclerosis can’t be correct”. The obvious problems with this supposed falsification test are that the theory calls for an effect that is (i) based on cumulative intake, (ii) manifests itself over a longer period than four months and (iii) is part of a complex system called he human body that is only partially understood. You would have to run the test over a much longer period and with more than one person and varying levels of fat intake to reliably test the theory. Similarly, observing that “hey we kept pumping a lot of CO2 into the air between 1940 and 1970 and temperatures didn’t go up” does not falsify the hypothesis that CO2, all else equal, increases tempertature over time. I’ll refer to this as the “localized fallacy” each time Milloy uses it in order not to have to repeat this argument.
Of course, this means that the temperature record over similar time periods or geographies can not logically be used to demonstrate that the theory of human-caused global warming is true either. This is why temperature records do not provide compelling evidence either for or against human-created global warming. (Incidentally, it’s also why I called out in my article that temperature swings should not be the basis for accepting a link between human activity and global warming.)
And let’s not forget the third-rail of global warming debate – one that Al Gore carefully slid over in his movie – the actual relationship between carbon dioxide and global temperature.
While alarmists would have us assume that increases in atmospheric CO2 precede and cause increases in global temperature, the scientific data say the exact opposite.
Historical data taken from polar ice core samples indicate that increases in temperature have preceded increases in atmospheric CO2 by several hundred years. Not letting this “inconvenient truth” spoil his movie, …
Gore’s movie was a bad joke, and he was misleading in the way he presented this information (among many other things). There are plausible theories for CO2 acting as an amplifier for warming incidents started by other instigating factors. Nobody knows if they are correct. Once again, this information (like everything we see in the temperature record) neither confirms nor falsifies the hypothesis. It simply emphasizes our profound uncertainty about the climate.
…Al Gore only describes the relationship between atmospheric CO2 and temperature as “complex.”
Indeed, it is.
So I guess, Milloy, Gore and I all agree that the relationship is complex. Complex here is a synonym for “not well understood”. Apparently, Gore thinks “not well understood” means “will definitely destroy us”, Milloy thinks “not well understood means “no big deal”, and I think “not well understood” means “I don’t know how big a deal this is”. Or as I said in the article: “Global warming is a real risk, but its impact over the next century could plausibly range from negligible to severe.”
So why let it get in the way of the most subtle yet audacious political power grab of our time. Manzi has taken Gore’s bait and is running with it. We’ll get to the politics in a moment, but there are a few other points to make about Manzi’s presentation of the science.
Manzi writes that, “The most important scientific debate is really about…feedback effects,” by which he refers to the notion that changes in atmospheric CO2 cause a complicated set of feedback effects that supposedly magnify and reduce the greenhouse effect. Manzi specifically mentions that higher atmospheric temperatures melt the polar ice caps, which in turn, supposedly causes more warming, and that more atmospheric CO2 increases plant growth which removes CO2 from the atmosphere, thereby cooling the climate.
The reality, however, is that these feedback loops are hypothetical in nature and no one really understands them, if they exist. No one knows why the Arctic ice caps seem to be receding. Glacial melting is a complex geologic event that seems to have little to do with atmospheric temperatures.
When it comes to feedback effects, let’s parse “if they exist” from “no one really understands them”.
On the point of their existence: I challenge Milloy to find one credible atmospheric scientist who claims that climate feedback loops do not exist. This is crazy. He’s basically saying that you can change some aspect of a complex, integrated system without impacting other aspects.
On the point of our current level of understanding these feedbacks: I yield to no man in my insistence that we have no validated capability to model net feedbacks with sufficient precision to forecast the impact of various emissions scenarios with meaningful accuracy. I devoted about the first third of my article to explaining why this is true and why it is central to the debate. I have previously written a lengthy article for NRO that focuses solely on the science behind this exact point. I have posted repeatedly on this point, such as here, here and here.
Milloy doesn’t seem to get that “I don’t know” is not the same thing as “No reason to worry”.
During the warming period from 1880 to 1938, it’s estimated that the atmospheric CO2 increased by an estimated 20 parts per million. But from 1938 to 2003 – a period of essentially no increase in Arctic warming – the atmospheric CO2 increased another 60 parts per million. It doesn’t seem plausible, then, that Arctic temperatures are significantly influenced by atmospheric levels of greenhouse gases.
Global warming worriers can take no comfort from Antarctic data either. Over the last 30 years, atmospheric CO2 increased by about 15 percent, from about 328 parts per million to about 372 parts per million. But the Antarctic temperature trend for that period indicates a slight cooling. This observation contrasts sharply with the relatively steep Antarctic warming observed from 1949 to 1974, which was accompanied by a much more modest increase in greenhouse gas concentrations.
As to trees removing CO2 from the atmosphere, well, some do and some don’t.
Researchers from the Lawrence Livermore National Laboratory recently reported in the Proceedings of the National Academy of Sciences (April 17) that while tropical forests exert a cooling influence on global climate, forests in northern regions, because of their absorption of sunlight, exert a warming influence — and it’s not just a trivial climatic effect.
Based on the researchers’ computer modeling, forests above 20 degrees latitude in the Northern Hemisphere — that is, north of the line of latitude running through Southern Mexico, Saharan Africa, central India and the southernmost Chinese island of Hainan – will warm surface temperatures in those regions by an estimated 10 degrees Fahrenheit by the year 2100.
Having told us over and over about how we don’t know jack about the global climate system (we don’t even know if feedbacks exist!), Milloy now cites “researchers’ computer modeling” to tell us that something as specific as planting trees in a particular part of the globe, but not another, will have the counter-intuitive effect of increasing warming. You can’t have it both ways.
Contrary to the claims of this simulation model, we don’t know what effect planting trees above the 20 degree lat line in the Northern Hemisphere would have on regional temperatures, because no climate model has ever demonstrated good fit simulating temperatures at the level of major regions of continents, even based on much more fundamental climate drivers .
It would seem that climate jihadists might well start their anti-warming campaigns in the chainsaw isle of their local hardware stores, rather than coming for our SUVs, incandescent light bulbs and thermostats.
Milloy ends the science section of his article with more rhetoric.