There is no help for it. No one would write a book on this subject unless he or she felt strongly about it, and a reviewer needs to make clear his own starting position. I don’t disagree with everything – far from it. The core of the climate change proposition, as set out in the most recent (Fourth) Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), can be stated simply (i) the planet is warming; (ii) the warming is unprecedented; (iii) human beings are responsible; (iv) the way forward is to reduce our emission of greenhouse gases; and (v) we must do it now, or very soon (one or two of the orthodox would say it is already too late). Professor Eggleton follows this line of thought in his book. I have reservations about the orthodoxy, and thus about his conclusions.

On the evidence, the first IPCC claim is likely to be true; the second cannot be known; the third is likely to be responsible for at least some warming; the fourth seems impossible to achieve in any short time frame; and the fifth is simply an assertion based on the scariest possibilities. The orthodox, using the same evidence, will say that I am missing the point, or not recognising the important findings, or waving aside the opinion of the ‘ninety-seven per cent’ of those qualified to make a judgement, or that I am not a climate scientist, or am indifferent to my grandchildren’s future. Adequate responses can be made to all such objections, but the debate goes on and on, because ‘climate change’ is ultimately about the status of human beings, and our future on the planet. It has both a strong religious overtone and a great capacity to affect the way we live.

For the IPCC orthodoxy is the basis of the Australian carbon tax, the European Union’s charges on flights into Europe, the subsidisation of solar and wind power in many countries, including Australia, and many other actual or proposed measures to mitigate global warming. There are many who disagree, and they come from a variety of positions. The religious fervour of some of the orthodox, in occupying the moral high ground and finger-wagging the rest of us to persuade us to reduce our carbon footprint, can and does get people’s backs up. The increased price of energy has hit everyone, and not all consumers happily accept that the high prices show their willingness to save the planet. And there are well-informed sceptics, lots of them, who ask inconvenient questions.

There are few real debates (I have taken part in two, both polite and inconclusive). For the orthodox as well as most governments, the science is settled: they have moved on, and are only interested in looking at mitigation – reducing emissions. For the dissenters, the science is inconclusive, and does not require that we try to ‘combat climate change’. Dissenters prefer adaptation to mitigation. Eggleton wants mitigation. His approach is low-key until the last chapter, systematic and well-argued, with plenty of references, charts, pictures, and graphs. He advances the IPCC argument, but does allow that there are dissenters. For me what he puts forward is familiar ground, and I have little quarrel with what he claims is the basic science. Much of it can be interpreted in a number of ways, and that is the problem. Furthermore, so-called ‘climate science’ is a new field, and all the established people in it come from older, established disciplines: physics, meteorology, statistics, geology, chemistry, oceanography, and so on. They bring with them their own tools and interests.

Eggleton is a geologist, and a respected one. He takes issue with two other professors of geology: Bob Carter and Ian Plimer, both sceptics. Plimer is, incidentally, a Eureka Prize winner. All three have written books worth reading. What is the hapless seeker after knowledge to do? My answer is that one should make sure that one’s reading diet in this area is balanced. Readers will still be unsure about many things when they have finished. So am I. We are a long way from real knowledge in this domain. Let me give some examples of why there is uncertainty, and why I have criticisms of Eggleton’s book, and of the IPCC position that it supports.

First, like so many in this field, both orthodox and dissenting, Tony Eggleton takes the measurements of temperature as given, and thinks that the ‘global temperature anomaly’ is a meaningful construct (it purports to be the difference between the world’s average temperature today and the average of a baseline measured from 1961 to 1990). There is much error in the temperature data, and the errors become greater the further back you go. It is most likely that the earth has warmed over the twentieth century, but we cannot be sure by how much. The notion that we can know that last year was hotter than its predecessor, to three decimal places, is nonsense.

Second, the warming may or may not be unprecedented, but we have no real knowledge, not only because we can’t measure the average temperature of the last century accurately, but also because the proxies used to measure past temperatures come with their own uncertainties.

Third, humans must have had some effect on temperature, since the physics of radiative transfer is clear, but increased carbon dioxide cannot be the only important effect on temperature, because carbon dioxide emissions keep going up while temperature wanders around, even if it seems on average to be getting warmer. We still don’t know what causes climate’s ‘natural variability’, and we cannot distinguish this from carbon dioxide’s effects.

Fourth, while in Australia there are good economic reasons to look for alternatives to oil, significantly reducing emissions now is probably impossible to achieve without causing economic recession, and could have only a small effect on temperature. A worldwide agreement to limit emissions is beyond us.

I liked the way Eggleton began his book, but as I read through it I developed a growing sense of unease. For him there is little uncertainty, despite his apparent even-handedness in considering opposing points of view. The last chapter is particularly scary in its ‘predictions’, which are only projections based on possible scenarios developed in computer models. I do not buy them, and I think it will be twenty years or more before we have a decent handle on what affects our climate.

In the meantime, books on the subject will regularly appear, and passions will remain high, until another bugbear becomes fashionable.