Saturday, November 28, 2009

Durkin's Great Global Warming Swindle revisited

Over on the Daily Mail climate change debate, Wayland says "I have reluctantly changed sides after watching The Great Global Warming Swindle".

Although this TV polemic came out in 2007, it bears another brief refutation here.

This Channel 4 programme rested on these assertions.

1 "The record for 1940-70 shows cooling while CO2 was rising".
This graph shows that when all inputs are factored in, the result is consistent with scientific climate theory

2 "The troposphere (lower atmosphere, particularly that ~5 miles above the surface) air should warm faster than the surface". There is a gap in knowlege here, but more recent work is changing this situation.

3 "Temperature leads CO2 by up to 800 years in the ice cores, in the very long, interglacial timescales".

There is a positive feedback loop in effect, where higher temperatures, believed to be started by changes in solar input to the Earth, lead to more CO2 (from forest fires & outgassing from the oceans) which leads to more warming. The glacial - interglacial swings of temperature are thought to have been initiated by Malinkovitch cycles, but the duration of the cycle cannot be explained without factoring in CO2 -induced warming.

Note that this refers to very long timescales; for us humans, the concern is what has happened in the last 150 years, where CO2, undeniably a greenhouse gas, has undeniably increased, at the same time that temperature has undeniably increased. There is no 800 year time lag at present. Only wish there was.

4 The programme advances solar as the cause for the recent increase in temperature, but the science shows that solar changes to not correlate to the observed increase in recent years. This graph

shows a fair correlation between temperature and solar activity before 1970, with a marked divergence thereafter.

The programme repeated the myth that volcanoes emit more CO2 than humans. Not true. The sum total of all CO2 out-gassed by active volcanoes amounts to about 1/150th of human emissions, and the CO2 concentration curve is smooth, and does not reflect volcanic activity.

These are the main failings of the Swindle programme. The regulator Ofcom ruled that the programme had unfairly treated Sir David King, the IPCC and Professor Carl Wunsch. The programme makers with drew two assertions, but Bob Ward (former spokesman for the Royal Society), hold that this leaves five points uncorrected.

Channel 4 defended the programme as a polemic, an essay in stirring controversy, rather than a serious piece of scientific work.

What is happening to our home planet is serious. We should base our judgments about what to do on the whole picture, not on fragments presented in a polemical TV programme by people with an ideological axe to grind. Durkin, the film maker, has a political agenda, having moved from the Revolutionary Communist party, via Living Marxism to an extreme libertarianism.

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