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Policy, Uncertainty and Global Warming

The Australian today contains a link on its front page to an article entitled ‘Academic cool on warming’(,25197,23509775-2702,00.html) together with a link to a recent speech by the retired Vice-Chancellor of the University of Canberra Don Aitken entitled ‘A Cool Look at Global Warming’

( Aitken urges agnosticism regarding the scientific evidence for anthropogenic global warming. Aitken is no expert on climate science, his expertise lies in the fields of political science and history. However, his best points are political rather than scientific points, so this is not a reason to dismiss what he has to say out of hand. Aitken’s main contention is that the consensus view on the extent of the danger of climate change that the Intergovernmental Panel on Climate Change (IPCC) advocates is a political creation rather than a genuine consensus of scientists; and he is convincing in arguing that the IPCC consensus is most unlike scientific consensuses that have emerged over time and that it appears to be manufactured, at least in part, by political pressures. So it is wrong to call the IPCC case for anthropogenic global warming a received view in the same way that the Theory of Evolution or the Universal Law of Gravity is a received view. He also makes the good point that the evidential basis that underpins the IPCC consensus is dangerously over-reliant on predictions generated by models of the global climate. But reality is much more complicated than our simple models allow. We don’t understand the many ways in which causal factors that are relevant to creating the earth’s climate interact, and it is dangerous to presume that we do understand such matters.

      The global climate is the end product of the interaction of many factors. If we interfere with it, it is difficult to predict what the consequences will be. Many climate scientists argue that the IPCC consensus is our best estimate of the potential effects of anthropogenic global warming, however, as Aitken points out, some scientists argue that the IPCC overstates the case. Also some such as James Hansen, a climate scientist from NASA, argue that climate change will be much more extreme than the IPCC predicts. See

This is why agnosticism about the IPCC consensus is an appropriate attitude for Aitken to take. What is unfortunate is that Aitken lacks the courage of his agnostic convictions. In his ‘A Cool Look at Global Warming’ he repeatedly conflates sensible agnosticism with atheism about climate change. His ‘agnostic summary’ of his overall view is that ‘The earth’s atmosphere may be warming, but if so, not by much and not in an alarming or unprecedented way’. This is not genuine agnosticism at all, but an indication of a preference for one position in the debate. Aitken does introduce some evidence for this position, but it is plainly not sufficient to pass the sceptical challenges that he sets for the IPCC consensus, so it is not a position that a consistent climate change agnostic should feel compelled to move to.

      Aitken is not a consistent climate change agnostic, however he does argue that there are policy implications that follow from climate change agnosticism. He thinks that the appropriate policy response for the agnostic is to urge that we do nothing about climate change until such time as sufficient evidence becomes available to prompt us to abandon agnosticism for a particular position. This strikes me as dangerous advice. Given that the potential consequences of climate change are devastating, including the deaths of millions and the extinction of large numbers of species, it is prudent for the genuine agnostic to urge that we take those precautions we can to mitigate the effects of climate change while we can, even if there is a non-insignificant chance that climate change will not occur. Aitken is aware that some agnostics will reason as I have and argue that we should take climate change seriously even if we do not know for sure that it will occur. He associates such reasoning with the precautionary principle which, he argues, is a flawed principle. I agree with him that the precautionary principle is a flawed principle (See my earlier post ). However, one does not need to appeal to the precautionary principle to make the case for precautionary action on the basis of a possibility. Ordinary cost-benefit analysis will do. If the possible benefits of acting now to reduce the threat of climate change are high and the costs of preventative action are low compared to the potential costs of inaction, then the possibility of climate change being real (provided that it is not a vanishingly small possibility) is a sufficient rational basis for precautionary action.

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