Saturday, November 8, 2008

Faith-Based Climate Models? (I)

In a recent FORBES article (Oct. 27, 'Faith-Based Models', p. 105) columnist Peter Huber takes global warming models to task in a variety of ways. His general conclusion is that "outsider faith in global warming has to be grounded on trust in higher authority, disconnected from any critical scientific reflection at all".

Of course, this dreck enables him to then go on to assert that "promoting that kind of faith is the exact opposite of what science teachers should be doing".

The truth, of course, is far different. That is, that any reasonably intelligent (and curious!) person can convince himself that antrhropogenic global warming is real by simply perusing the essential climate literature. It also helps to at least have some background in thermal physics.

Let's take a look at a few of Huber's complaints to see if any have merit. The first is what he claims is a standard drawing or graphic in schoolbooks. That is - sunlight entering the Earth's atmosphere warms its surface, but then after this heating, its longer (infrared) wavelengths are blocked on re-emission from the surface so that a greenhouse effect takes hold. Huber complains:

"In fact, direct radiation from the surface into outer space plays only a small role in cooling the Earth. Far more important, the chimney like motion of hot air and evaporated water that transfers heat from the surface into the atmosphere".

Of course, he is referring to convection in the atmosphere. However, I would not go so far as Huber in saying that the other graphic amounts to "miseducating children". What it means, is that we employ an admittedly simplified cartoon (or ansatz) to convey the concept.

By adding in convection and its details, as well as cloud cover etc. one would clutter the concept and make it overly complicated for a school child.

This is not unusual at all, and is done all the time in science. For example, when I gave astronomy courses at the Barbados Community College, one graphic I often used showed how energy was transferred from the Sun's core to the photosphere. A zig-zag path was used to represent the photon trying to emerge from the solar core (wherein it was absorbed and re-emitted in different directions) until finally getting to the convective layer, and thence to the photosphere from where it could depart into outer space as electro-magnetic waves.

In many respects, the energy transmission graphic is as simplified as the one for the greenhouse effect which Huber criticizes in grade school general science books. The reason is that in fact billions of photons are in transit, and each taking an average of one million years to get out of the solar core because of the absorptions and re-emissions (by core atoms) in different directions. But this more factual depiction is clearly impossible to show, and would not in any way enhance the teaching of the underlying concept.

Huber himself then goes on to make a classic mistake when he avers:

"When not miseducating children, the climate modelers try to call a chimney a chimney. They recognize that cloud cover and water vapor eclipse carbon dioxide as the dominant greenhouse agents."

In fact, H20 vapor does not eclipse CO2 as a greenhouse agent. Even a tiny, minuscule amount of CO2 is vastly more efficient at blocking the re-radiation of energy than any amount of water vapor- at those bands. (See the NRC Report published ca. 2001 that gives the relative W/m^2 forcing contributions of each greenhouse gas) Part of the misconception arose because early researchers, lacking the current technology of infrared spectroscopy, assumed that water vapor bands already blocked out most of what would (ordinarily) be taken by CO2. (Cf. ‘The Discovery of the Risk of Global Warming’, by Spencer Weart, in Physics Today, Jan. 1997, p. 34).

As to cloud cover, a very useful reference here is the paper: ‘Can Earth’s Albedo and Surface Temperature Increase Together’ in EOS- Transactions of the American Geophysical Union(Vol. 87, No. 4, Jan. 24, 2006, p. 37).

As the authors note, though there is some evidence that Earth’s albedo (ratio of the radiant flux falling on a surface to that reflected from it) has increased from 2000 to 2004 this has NOT led to a reversal in global warming. The authors cite the most up to date cloud data released in August, 2005 from the International Satellite Cloud Climatology Project (ISCCP). The data – from a range of meteorological satellites covering the entire Earth, discloses the most likely reason for the anomaly is primarily in the redistribution of the clouds.
Thus, as the authors point out (ibid.):

"whereas low clouds have decreased during the most recent years, high clouds have increased to a larger extent leading to both an increase in cloud amount AND an increased trapping of infrared radiation."

Prof. Gale Christianson in his book Greenhouse (Penguin, 1999, p. 203)notes that “stratus clouds are gray, dense and low flying and have a net COOLING effect since their albedo is relatively high”.

BUT these are precisely the cloud type that has receded in incidence, as the ISCCP data show, from the EOS article! Now, what type has increased? Christianson again (ibid.):

“Conversely, wispy high flying cirrus are semi-transparent to incoming sunlight but block infrared radiation emitted by the Earth thus CONTRIBUTING to the Greenhouse Effect”

Again, the point I am making is that the use of the ansatz in school texts )to depcit the global greenhouse) is nowhere near as bankrupt educationally as Huber makes it out to be.

More on this in the next instalment.

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