Wednesday, 12 December 2007

Cargo Cult Science

In keeping with the theme of cargo cults mentioned as a problem with computers in education, let's look again at another field where the outward appearance of science is sufficient: climate change doubt.

One Ernst-Georg Beck has attracted some attention through publishing a paper claiming that CO2 variation was much greater in the immediate pre-industrial era than today.

One bunch of comments not only spruiks this doubtful paper, but also repeats a claim that Mount St Helens spewed out more CO2 than all industrial sources since the start of the industrial age.

Let's give you a hint. Increasing atmospheric CO2 by 1 ppm represents about 7 gigatons of CO2.

In one of his graphs, Beck has atmospheric CO2 dropping by 100ppm over a single year, and increasing in other places almost as fast. 100ppm represents about 700Gtons of CO2 – if you are talking about the entire atmosphere. Since he claims his results are accurate to at worst 3%, he is proposing that there was some sort of CO2 sink that can absorb CO2 at that rate, but which has somehow magically switched off in the last century. And some sort of pre-industrial CO2 source that was equally magical.

A more rational interpretation of his data is that early measures had gross experimental errors. For example, we are exhaling CO2; if you are measuring in parts per million, it is extremely easy to contaminate the data.

As for volcanic output of CO2, I prefer to believe sources who are working in the field, e.g., How much CO2 did Mount St Helens' eruption in 1980 release into our atmosphere? Can you give me some idea of how much CO2 volcanoes add to the atmosphere generally?, Scott Rowland, University of Hawaii and Steve Mattox, University of North Dakota and A Compilation of Sulfur Dioxide and Carbon Dioxide Emission-Rate Data from Mount St. Helens during 1980-88, U.S. Geological Survey Global Change Research Program. The maximum daily output from Mt St Helens was about 23ktons. Contrast this with 10-billion tons of CO2 produced by power stations worldwide annually (about 27-million tons a day) and you have to conclude that someone is talking nonsense.

(I suspect there is some mixing in the various reports of metric and old fashioned tons but the difference is insignificant on the scales we are talking about here.)

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