Saturday, March 03, 2012

Nordhaus on global warming

Yale economist William Nordhaus, who has studied cost-benefit aspects of potential policy responses to global warming, responds to this recent editorial.

I don't find Nordhaus completely convincing (in fact his discussion of the performance of climate models, point 2, alarmingly misses the point), but the article is worth reading.

NYBooks: ... Then, I saw an opinion piece in The Wall Street Journal of January 27, 2012, by a group of sixteen scientists, entitled “No Need to Panic About Global Warming.” This is useful because it contains many of the standard criticisms in a succinct statement. The basic message of the article is that the globe is not warming, that dissident voices are being suppressed, and that delaying policies to slow climate change for fifty years will have no serious economic or environment consequences.

My response is primarily designed to correct their misleading description of my own research; but it also is directed more broadly at their attempt to discredit scientists and scientific research on climate change.1 I have identified six key issues that are raised in the article, and I provide commentary about their substance and accuracy. They are:

• Is the planet in fact warming?
• Are human influences an important contributor to warming?
• Is carbon dioxide a pollutant?
• Are we seeing a regime of fear for skeptical climate scientists?
• Are the views of mainstream climate scientists driven primarily by the desire for financial gain?
• Is it true that more carbon dioxide and additional warming will be beneficial?

As I will indicate below, on each of these questions, the sixteen scientists provide incorrect or misleading answers. ...


LaurentMelchiorTellier said...

On par with missing the point in subject 2, is his falling into the very error he accuses his opponents of in subject 1: incorrect inference, by omission of context. 

Besides the fact that he does not refute the basic WSJ claim of the lack of warming within the claimed timeframe (10 years), nor the claim that this contradicts the computer models being refuted,  Nordhaus then goes on to revise a narrow, 10 year timeframe, in which warming is lacking, to a cherrypicked 100 year timeframe, within which warming occurs. 

On the one hand, this misses the point that the earlier half of this warming is not likely to be significantly due to (largely unchanged...) carbon dioxide levels, but must be due to the natural variations which he critiques WSJ for ignoring.

And on the other hand, it refrains from expanding the timeframe to 1000 years... to include the medieval warm period. Or millions of years... the context within which current rates of warming - both in absolute temperature, rate of change, and acceleration of rate - are so unremarkable. Expanding context to refute a point does not make sense if you expand only to exactly the extent that allows you to make your point, but no further.

Likewise, the refutation of subject 5 misses the point made by the WSJ article, at a level equal to subject 2.

The (very informal...) WSJ article barely can be called an argument against catastrophic AGW, and there are good cases and good proponents for catastrophic AGW. But Nordhaus does not seem to be one of them.

LaurentMelchiorTellier said...

As an aside, I think I'm not the only one who would be appreciative if this blogpost does not get hijacked into the usual ethnic partisanship sidetrack. You know who you are, usual suspects. ;-)

tractal said...

I agree, his failure to address point #2 is really disappointing. He covered the issue in a way which looks rhetorically like an effective response, but says nothing substantively. Of course all the New Yorker readership will read it like a knock-down argument, when it actually says nothing.  The same is true of point #3. He is attacking the idea that Co2 is not a pollutant in the environmental sense with an argument that it is a pollutant in a legal sense... Thanks for this link. If anything it makes me even more suspicious of the orthodoxy. 

Andrew Brereton said...

What do you think about the performance of climate models Steve?

steve hsu said...

I don't claim to be an expert, but my general experience with modeling complex phenomena is it is very easy to have much more confidence than is really warranted in your model. Therefore I think it is reasonable for an outsider to be skeptical as to whether existing climate models can really predict the future, or whether they have really properly characterized the dynamics. Nordhaus' response indicates he doesn't appreciate this point.

Off the top of my head I can't think of any complex systems (e.g., stock market, macro economy, the solar cycle) that we have good predictive models for.

Oneil said...

            can you give us your opinion on the editorial Nordhaus responded to?

RKU1 said...

Well, I don't have any expertise on the theory of human-induced CO2 Global Warming, but one very effective criticism I've read centered on the worldwide Great Depression.  Apparently, global industrial production fell by about one-third, and since heavy industry dominated in those days, it's likely that human CO2 emissions fell by a comparable amount.  The economic situation went on for roughly a full decade across most of the world.

Despite this, there's supposedly no sign of any "kink" in the global CO2 growth curves of that era, based on tree-ring analysis or that sort of thing.  This would tend to strengthen the argument that CO2 levels are actually a *consequence* rather than a cause of Warming.  At the very least, it seems to me that if a one-third drop in CO2 emissions worldwide for a full decade had no impact on CO2 trends in the atmosphere, it seems unlikely that any of the current measures being proposed will have much impact either.

I wonder if any of the commentators here who've investigated the Warming issue are familar with this particular point and what that standard pro-Warming refutation might be.

LaurentMelchiorTellier said...

By chance, I'm familiar with it. But all you really have to do is look at graph 2 of my post above, you can see the kink for yourself, late 1930s. 

Unlike world temperature (which is a profoundly messy business to measure), we have pretty clear and unambiguous numbers for world CO2 concentration in ppm. There's isn't "localized CO2 concentration" in the same way as there is for degrees Kelvin, CO2 disperses too efficiently. So, what we see for the period in question is that the depression was a period of warming, immediately preceded and followed by periods of cooling, during a period of reduced rate of CO2 increase. 

To be fair though, although I'm unconvinced by catastrophic AGW, the depression period is a poor example of anything, either way. It's mere a slight reduction in the *rate* of CO2 *increase*. But the CO2 concentration itself was still increasing. 

RKU1 said...

Thanks!  It's always helpful to have smart, knowledgeable people around to answer ignorant questions.

And you're certainly correct about a kink in the curve.  I'm sure I must have misremembered what I'd read a few years back, confusing claims of a no-kink CO2 curve with a no-kink temperature curve or something along those lines.

Albert Magnus said...

I think people outside atmospheric science put way too much emphasis on the computer models. The scientists doing this work are aware and are very disciplined about showing their uncertainties. Its the communicators and the activists that tend to babel about nonsense.

RealClimate just posted an update of various climate models from about a decade ago compared with real data, including for Ocean heat content and arctic ice.

Albert Magnus said...

People should always talk about and try to quantify the statistical and systematic uncertainties about whatever time interval they are talking about. If you do that, then I wouldn't consider it cherry picking either way.

Albert Magnus said...

Also, comparing ice core data from a 10,000 years ago or tree ring data from 1000 years ago to modern atmospheric temperature measurements should be done with all sorts of care. They aren't the same set of information.

Bobdisqus said...

I spend my time creating variation models of autos which are a good bit simpler and struggle to imagine the hubris it would take to claim one had a model of the earth’s climate capable of predictive value.

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