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Some concluding thoughts about climate change

By Don Aitkin - posted Monday, 28 June 2021

Climate change got me into establishing and maintaining a website, so it's fitting that I farewell the website (almost) with a comment about this vexed issue. As with defence, nothing much has changed since I first got interested in the issue twenty years ago. Very briefly, I was writing a book about Australia twenty years from now (= then = 2002), and it needed a chapter on 'the environment'. That took me to global warming, and on the advice of a friend or two, including Ian Castles, the former Australian Statistician, I ploughed through the WGI paper of the Third Assessment Report of the IPCC. I became more and more sceptical as I read on, explored much more stuff and then started to give addresses and write essays on the subject. In 2012 I decided I might as well set up my own website, and did so.

As I wrote above, nothing much has changed except in detail. The orthodoxy is that carbon dioxide is being manufactured through human activity at a rate that threatens humanity and even the environment of the planet. CO2 is a villain, indeed, the villain, and no other issue is as important, not even Covid. The nations of the planet must band together to reduce our dependence on fossil fuels, the source of this gas, and come to rely exclusively on alternative sources of energy, often named (erroneously) as 'sustainable'. Governments, pressed by Green and other environmental groups to 'do something', have waffled on about 'climate action', which has led to a bewildering mix of energy sources, but fossil fuels remain the dominant provider, especially of electricity.

I thought that Working Group I paper was very short on good data and over-reliant on its basic premise, that CO2 was the villain, and its work was all about showing how that might be so, not about testing the hypothesis against data. Subsequent Assessment Reports from the IPCC, a political body, not a scientific one, have been no better, and there is a new one coming later this year, I understand. I don't see much sign of improvement there. As the data become even more contingent, so the rhetoric of the orthodox and their media allies becomes even more strident.


I don't see any compelling reasons to support the orthodoxy, despite the plethora of organisations that have now signed up to it. Here are a few reasons why I remain sceptical. I've written about all of them before.

First, the orthodox claim that what we are experiencing with our climate is quite 'unprecedented', and that is in part why there is a rush to find solutions, gain global agreements, ban fossil fuels, and so on. It is not always clear what it is that is said to have no precedent, but the historical evidence is that humanity has endured some cold periods, like the Little Ice Age and enjoyed some warm periods, like the Minoan and Roman eras. These eras were not marked by abrupt increases or decreases in carbon dioxide, at least so the proxies say. I find it hard to see anything truly unprecedented in our present climate.

Second, there is general acceptance that a doubling of carbon dioxide in the atmosphere would lead, of itself, to an increase of about one degree Celsius in global temperature. But the climate models, on which the orthodoxy relies, say that there is an additional factor, called 'climate sensitivity', that has to be considered. This factor multiplies the warming effect by 1.5 to 4.5 times, and could lead to 'runaway warming' and 'tipping points'. Efforts to find and measure climate sensitivity have produced a wide range of results. For my part, this is the crucial weakness in the orthodox position. For a doubling of CO2 that produces a one-degree increase in global temperature is not worrying at all, and it will take a long time to generate that increase in temperature anyway. The only reason that we need a concept like 'climate sensitivity' is that the models demand something much more alarming. Climate sensitivity was created to provide it.

Third, what measures we have of global temperature do show an increase from about 1965 to 1998, a period in which the amount of CO2 certainly did increase, almost matching the shape of the increase in temperature. Many people found that agreement to be most alarming, and blamed it on the villainous gas. Between 1920 and 1950, however, there was a similar rise in global temperature, but no corresponding increase in CO2. What caused that increase? Ah, said the orthodox, that's natural variation. Well, asks the sceptic, why isn't the post-war increase also due to natural variation? That's because of the extra CO2? Really? My judgment is that human activity has been part of the cause of the post-war increase, but it is not of much consequence. And in any case,

Fourth, all the orthodox anxiety about warming is based on the premise that warming is bad, and could get worse. In fact, there is no evidence that warming has been bad for anyone. On the face of it, the slight amount of warming that has occurred over the past century has been beneficial to plants and animals. Cold is the real worry. Similarly, the increase in carbon dioxide has not led to a 'climate emergency'. What is the evidence for such an emergency? On the contrary, there has been a perceptible greening of the planet over the past forty years. Plants love CO2, and animals love plants. The greening has been a win/win.

Fifth, the orthodox have worries about sea-level rises, and 'ocean acidification'. Sea levels have been rising for several centuries, and there does not seem to have been a recent sudden acceleration in that rise. Not one, anyway, that can be credited to extra atmospheric CO2. 'Ocean acidification' is an alarming (but mis-named) concept, but if there is a shift in the alkalinity of the seawater it is hardly measurable, and in any case the oceans possess a variety of hot spots and low spots, and sea creatures seem to survive, even flourish, in both extremes.The orthodox claim that extreme weather is the consequence of climate change, but there is no good evidence to support this claim.


There are other reasons to be sceptical, and I haven't time or space to go into the awful mess we are in because of the desire to replace fossil fuels with 'alternative' energy sources, and the hype about electric vehicles. Enough is enough. My conclusion is that governments everywhere would love to be out of this bind, but they feel they can't, because of possible electoral backlash. So I shake my head, and go on puzzling that what ought to be a matter of rational debate and good data has become a matter of passion and principle.

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About the Author

Don Aitkin has been an academic and vice-chancellor. His latest book, Hugh Flavus, Knight was published in 2020.

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