Arnold Kling  

Global Warming and Model Dependence

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Woof!... I am not a Populist...

J.S. at Environmental Economics writes,


We all are aware of the well-funded campaigns to discredit the science of global warming, and I’m the last one who wants to add more uncertainty to the mix.

He points to this set of charts put together by Monte Hieb, which shows that man-made carbon dioxide is a very small component of total greenhouse gases. The charts make the point that water vapor is 95 percent of greenhouse gases.

Not sure whether those charts were credible, I got some confirmation from NOAA's National Climactic Data Center.


Water Vapor is the most abundant greenhouse gas in the atmosphere, which is why it is addressed here first. However, changes in its conentration is also considered to be a result of climate feedbacks related to the warming of the atmosphere rather than a direct result of industrialization. The feedback loop in which water is involved is critically important to projecting future climate change, but as yet is still fairly poorly measured and understood.

I am starting to appreciate how extremely model-dependent the field of climate forecasting is. That is not a good thing. As I wrote here, "The complexity of the process far exceeds the availability of data needed to verify the model. Even a broad consensus may prove fragile."

Under the circumstances, I think that the language that climate forecasters should be using ought to be careful and cautious about what they claim to know. The argument for trying to control carbon dioxide emissions is actually quite subtle and nuanced.

The argument would have to start by saying that the relationship between man-made carbon dioxide and global temperature is highly nonlinear, and there is a very large margin of error in estimating the effect. The error could be that we over-estimate the effect of emissions on global warming, but it could be that we under-estimate the effect. Particularly if we under-estimate the effect, we would want to err on the side of curbing emissions.

To me, that is the strongest argument that one can make for curbing emissions and still retain credibility. The more that Al Gore and company argue something differently, the more I am inclined to reject their religion.


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TRACKBACKS (6 to date)
TrackBack URL: http://econlog.econlib.org/mt/mt-tb.cgi/525
The author at Eli Dourado in a related article titled DHMO Is A Killer writes:
    Arnold Kling points out that dihydrogen monoxide makes up 95% of greenhouse gases, much more than carbon dioxide.  When will we do something about this dangerous substance?  Clearly, this is some sort of government conspiracy. ... [Tracked on June 14, 2006 8:24 AM]
The author at Muck and Mystery in a related article titled Arnold Does Climate writes:
    It's a bit worrisome that I find that many of the most rational and sensible takes on climate change come from economists. In a better world it would be environmentalists, ecologists and such that would have the saner views since it is their business ... [Tracked on June 14, 2006 3:32 PM]
COMMENTS (3 to date)
dearieme writes:

The absorption of heat by CO2 is so close to saturation that you need to build some sort of amplifier into the models if you are to predict dramatic temperature rises. The one favoured in absorption by water vapour. Since it is, as they say, poorly understood, the whole "science" of Global Warming is in act-of-faith territory.

dearieme writes:

Ha, "subtle and nuanced" = requiring the suspension of your critical faculties.

aaron writes:

Complex systems tend to be self correcting.

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