The worst kinds of argument are those in which the opponents think that they are talking about the same thing, but there are fundamental differences in their basic assumptions. The climate debate in the media is one such argument. Journalists, along with the public, have a basic lack of understanding of the way in which science comes to conclusions. But to be fair to them, scientists are partly to blame because their public arguments tend to be expressed in the mode used by non-scientists, rather than explaining the nature of scientific reasoning. A little explanation is needed to clarify what I mean.
We all have a peculiar way of dealing with risk. We usually have a rational way of dealing with moderate risk and its companion probability, the sort of odds used in betting on horses for instance. We well understand how to respond to a 50:50 chance, or a one in three probability, but when the chances are at the extreme ends, we act in strange ways. Each time we take to the road in a car we know that there is a small but finite chance that some catastrophe will bring us to grief, but act as if there is no risk. If our bus turns up 99 times as scheduled, we will assume it will today, even though there is of course a small chance that today it will break down and not appear. In short, we like to have things definite and predictable. A prominent example is our legal system where we will send a person to prison (and in some countries may execute them), for a decision “beyond reasonable doubt”. The accused is labelled “guilty” even though we implicitly admit that the conclusion may be incorrect. But then this process is a necessary technique for everyday life, because if we dwelled on every little risk we would end up doing nothing. Real life is a long series of risk-taking.
Science works differently. Here the process is a step-by-step buildup of confidence. A proposal is made that something might be the case, and an experiment is performed to test it. The results of the test are published so that other scientists can criticise the test, or duplicate it, or check by some other method. If the results of the original test are supported, then confidence builds in the proposal, If not, it is discarded or modified. This is actually a rather idealised description of the process, but the principle of checks and balances building up confidence is genuinely at the core of scientific progress. So if you hear a scientist proclaim something like “Climate change is real”, what is really meant is “The probability is so high that we consider it certain”.
Sceptics on the other hand state quite baldly that climate change is a myth, and they seem to believe this absolutely. To them the probability is zero, and it is on this point that they should be challenged. Rather than climatologists having to strenuously defend every last detail of their case, they should be saying “OK, if the point you have made is correct, then all that happens is that our confidence will be reduced from, say, 95 per cent to 93 per cent. Now what is your evidence that reduces all of our other evidence to zero probability”. And there is another point of principle. It is an unwritten rule of science that it is the responsibility of the minority view to provide convincing evidence to counter the majority opinion, so once again it requires more than picking a few holes in the generally accepted evidence, or even claiming that there is an alternative explanation. The skeptics have to deliver a body of evidence that more than matches that of the established case, and that certainly has not been done by the climate change skeptics.
The buildup of evidence in support of climate change has been taking place for more than fifty years, with very few stalls along the way. Yes, you will have heard of challenges by reputable scientists, and some errors and even misbehaviour, but the revelations of these represent the strength of the case, the checks and balances at work, not its weaknesses.
In summary, when the debate on climate change turns from absolutes to probabilities, we will finally see the subject in proper perspective and get some sense into attitudes. It may be acceptable to assume the horse you back is a certainty but with climate, you are gambling on the future of your children and grandchildren. So turn off the shock jocks and make your own decision based on evidence.
Jeffrey Tapping
Retired CSIRO Physicist
Telegraph Point
