The Climate Caper
By Professor Garth Paltridge
Connor Court, A$24.95

The popular science shelves of our bookshops are brimming with books on climate change. Usually their authors either regurgirate the establishment views of anthropogenic global warming (AGW) or strive to supplant it with their own pet theories. The Climate Caper, by Professor Garth Paltridge, takes a different approach. Paltridge is an atmospheric physicist, so he has an excellent grounding in the uncertainties in our understanding of the physical processes that underpin the Earth’s climatic system. [He is also a committee member of the Australian Skeptics (Tasmania).]

The book is aimed at the general reader, though there is a moderately technical discussion of the modelling of feedback mechanisms. The argument is structured into chapters titled “Some Physics”, “Some Economics” and “Some Random Sociology”. The Caper spans these three areas of disciplinary focus.

The chapter titled “Some Physics” gives a general description of the climate models used in the IPCC forecasts, with particular attention given to the modelling of feedback gains. Paltridge begins by informing us that: “There are good and straightforward scientific reasons to believe that the burning of fossil fuel and the consequent increase in atmospheric CO2 will lead to an average temperature of the world above that which would otherwise be the case.” (p17)

It is uncontroversial to suggest that a doubling of CO2 levels from the pre-industrial level will result in a 1.2°C temperature increase. However, there are significant uncertainties in our quantitative understanding of the primary feedback processes (water vapour, cloud, ground reflection of sunlight and lapse rate) that amplify or dampen this effect. The sum of these feedback processes is known as ‘total gain’.

The models used in the IPCC process assign values of total gain between 0.4 and 0.8. Paltridge suggests this range of feedback values is suspiciously narrow. He takes this as a sign that “Either the individual process gains are ... correlated ... or there has been some subconscious choice of process description to keep the total gains of the various models within physically realistic bounds.” (p26) Other researchers, such as Row and Baker, demonstrate that this range of values follows the anticipated normal distribution without any sign of systematic bias.

Paltridge suggests that any narrowing disparities between model projections may be an artefact of code reuse, but at the same time he bemoans the number of tuneable parameters in models as giving the theoreticians too much flexibility. I would have thought that code modularity would have assisted the rapid development of alternative models and that this would have increased the diversity of research. If tuneable parameters aren’t being changed in an ad hoc way by researchers during their ensemble runs, then there would be little cause for concern either.

He says that models can only be compared to each other, although in other places Paltridge draws attention to the failings of climate models in recreating certain historical scenarios. Another suggestion is made that, owing to the steep curve of the feedback equation, outlying results would be skewed toward higher temperatures. This line could be further investigated with data from actual ensemble runs submitted to the IPCC.

On the economics of climate policy, Paltridge illustrates the difficulties of using cost benefit analysis over a 90 year time span to determine an optimal course of action. With reference to the Garnaut Report, he suggests that “The forecasting problem is much worse for the economist than for the climatologist.” (p38) and “The problem of calculating the long-term benefit of an expensive exercise to prevent climate change has every chance of being inherently insoluble.” (p39)

A fair comment for a skeptic. There are too many uncertainties in both the future state of our climate and the future worth of our climate to our economy to engage in any meaningful discourse of this kind.

However, Paltridge overshoots the mark when he says: “Whether society should do something about global warming boils down to whether it can be persuaded of two things. First, it must be persuaded that the coming of global warming is certain and that it will be detrimental. [...] Second, society must be persuaded of the greatness of the moral virtue attached to active personal sacrifice for the benefit of people 4 or 5 generations into the future.” (p57)

This reasoning is not so sound. Firstly, we need not be persuaded of the certainty of an outcome in order to take action to mitigate the risk of it occurring. Secondly, (as is acknowledged elsewhere in the book) a significant number of initiatives that would reduce our greenhouse gas emissions would also confer an economic benefit that is realisable in the short term.

In the chapter “Some Random Sociology”, Paltridge gives several interesting anecdotes with a common theme - the efforts of academics, climate researchers and bureaucrats to stifle public discussions of doubts within their ranks about global warming. The most disturbing of these situations was one Paltridge recounts when his own research was rejected by a peer-reviewed journal on the grounds that the reviewer thought it was an attempt give respectability to views that were outside of the recent IPCC findings.

Taken at face value, these anecdotes demonstrate a strong desire to present a united front among the scientific community on climate change which is at odds with a culture of free inquiry. This attitude is frequently characterised as an unwillingness to give ammunition to ‘the sceptics’ (a term used as a catchall for those questioning the existence or extent of AGW). It is not unreasonable to wonder if this kind of fortress mentality, combined with other established publication biases such as the file drawer effect, is contributing to a body of missing research.

There was no attempt in this book to differentiate between what might be termed climate skepticism and climate denialism. Paltridge and other diligent researchers, such as Stephen McIntyre and Ross McKitrick, who draw attention to flawed methodologies or data quality could be reasonably described as having skeptical positions. However, significant media coverage is given to other authors, lobbyists and commentators who confine themselves to a rhetorical or ideological engagement to AGW without making a scientific case. Tom Bethell, with his Politically Incorrect Guide to Science, would be a good example of this mindset.

I would have liked to have seen a more detailed treatment of the scientific merits of the views apparently excluded from the mainstream of scientific discourse. Mention is made of the response of the upper atmosphere to increased CO2 being ignored by climatologists, but the coverage is brief. While it may not have been Paltridge’s intent to produce an overly technical book, at the very least a selection of works for further reading would have been appropriate. Given the abundance of opinion pieces in newspapers, magazines and blogs, it would be preferable for Paltridge to offer a more detailed exposition of the technical uncertainties and cultural biases that he touches on.

Reference

Roe G, Baker M, Science Vol. 318. no. 5850, pp. 629 – 632 10.1126/science.1144735 Why Is Climate Sensitivity So Unpredictable?

Originally published in The Skeptic Vol. 29, No 4. December 2009
(https://www.skeptics.com.au/wp-content/uploads/magazine/The Skeptic Volume 29 (2009) No 4.pdf)