Wednesday, April 09, 2008

Climate Change Sceptics

Don Aitken has got coverage in today's The Australian for a speech he gave on climate change.

Aitken has done a remarkably good job of dealing with the justifiable doubts about anthropogenic global warming. In particular I support his eminently justified critique of the attempt to be doctrinaire about the so-called consensus. I could also quibble about his description of Paul Feyerabend as a political theorist rather than a philosopher of science, and to simultaneously assuming there is an established “scientific method” while also quoting approvingly from Feyerabend’s Against Method, which was an argument that there is no privileged scientific method.

In the end all we can have are theories, and we can have theories that are largely useful or theories that have been useful but are now less so, and eventually some of those theories may become “discredited”. With climate change we have a theory of the Greenhouse Effect; a theory I first heard at an ANZAAS conference in 1975 as an argument for nuclear power and hence treated by me with excessive scepticism.

It is a plausible theory, it is a difficult theory to fully demonstrate and model; primarily because weather patterns are what we now call chaotic systems. To the extent that there is evidence to support the theory it is “patchy” – the ice core correlations don’t prove cause and effect, short run warming measures are hard to interpret.

But Aitken also wants to discount a “precautionary principle”, based on a simple criticism of Pacal’s reason for believing in God – namely that in doing his expected value analysis the father of probability theory left out some other possible future states. However, in this case while there are multiple alternate theories there is still a simple binary choice between the “Greenhouse Theory is correct” or “it is not correct”.

The matter is very like the Pascal’s though in pay-off – acting to reduce emissions has a relatively low cost compared to the catastrophic outcome if the theory is correct. And just like Pascal, we can’t wait to make the decision. If we wait to see incontrovertible evidence of warming then we are too late to stop the process escalating. The one thing we do know is that the CO2 concentrations in the atmosphere are already at monstrously high levels.

I have elsewhere likened the issue to a General who refuses to believe the intelligence reports of a paratroop invasion until he sees the first invader on the ground. By then the other thousands are in the air on the way down and there is nothing he can do about it.

Finally, climate change reaction may in the end be just what we need. The theory known as “peak oil” is that the global economy will receive a massive shock when energy demands keep increasing at the same time as oil supply starts to decrease. The steps taken to reduce reliance on fossil fuels will also ease the risks of that shock.

What I find a pity is that the climate change discussion has become clouded in the same kind of pointless dialectic as the so-called culture wars - where persons on either side seem to think direct attacks on the other as being wrong in method are productive or useful. Aitken is right to raise his concerns about the climate bandwagon - but his proposed solution of a giant process to decide the "right" scientific answer is also wrong. We have to accept that at this point multiple theories have degrees of evidentiary support - the question is how to act in the face of that, not on how to decide "the truth".

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