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Nigel Lawson: Volcanic Ash And The Precautionary Principle

The revelation that the decision to close Europe’s skies following last week’s eruption of an unpronounceable Icelandic volcano, and the spewing of ash into the sky, was triggered by advice from the Volcanic Ash Advisory Centre of the UK Met Office, based not on all relevant empirical evidence but on their computer model, has led to no small controversy. IATA, representing the airlines, has condemned the advice as absurd and unnecessarily alarmist, while others have noticed the parallel with the drastic decarbonisation policies promoted by the climate change lobby, similarly based largely on alarmist interpretations of the projections generated by Met Office computer models.

However, the folly of everyone relying on Met Office computer modelling is only half the story. An even more important read-across concerns our old friend the precautionary principle.

What the Met Office/Volcanic Ash Advisory Centre model does is essentially to provide short-term predictions of the extent and location of the clouds of ash. It may well do this (not a very difficult task, after all) pretty accurately. It is clearly a very much simpler and hugely less uncertain task than predicting the likely temperature of the planet a hundred years from now. It is, however, a very limited model, which does not even pretend to predict the intensity of the ash within the cloud, or in different areas of the cloud. Nor, of course, does the VAAC have any knowledge at all of what level of ash intensity is a serious hazard to jet aircraft and what level is not a serious hazard. When tackled about the intensity issue by the BBC, the Met Office spokesman claimed that this was irrelevant, since the policy in force was one of ‘zero tolerance’. This, of course, is complete idiocy (and is conspicuously not the policy in the US, whose air safety record is as good as Europe’s). It is, however, the so-called precautionary principle again – and indeed only a few days ago the Eurocontrol spokeswoman was explicitly justifying the original blanket flying ban on the grounds of the precautionary principle.

The so-called precautionary principle, heavily used as the argument for hugely costly decarbonisation policies, is always and in all contexts a meaningless policy guide, since it is an elision of two injunctions, one of which – ‘be careful’ – is obviously right, and the other of which – ‘you can’t be too careful’- is equally obviously (at least after a moment’s reflection) wrong. If you can’t be too careful, if your approach to risk is one of zero tolerance, then you wouldn’t fly at all, ever. Nor would you take a train. And you would certainly never drive a car (or be driven in one). You might never even cross a road.

Rational decisions have to be taken on the basis of some empirical understanding of the risks involved, and on the balance between risk and reward (or the cost of avoiding risk).

Exposing the nonsense and muddle of the so-called precautionary principle is an essential part of the GWPF’s declared mission ‘to bring reason, integrity and balance to a climate debate that has become seriously unbalanced, irrationally alarmist, and all too often depressingly intolerant’. If the argument now raging over the policy response to the volcanic ash clouds assists in achieving this, it will demonstrate that ash clouds, too, have a silver lining.