Given that net zero is a risk management response to a perceived threat, one would hope that those who are both directly and indirectly responsible for establishing such policies would have a sound theoretical and conceptual understanding of risk and uncertainty. In particular, one would hope that they fully understand the basic principles of risk management and appreciate how risk and uncertainty are related. Unfortunately, although we are perfectly entitled to assume that such concepts are fully understood by those driving climate policy, this is actually not the case. I firmly believe that this shortcoming is one of the most important issues to be addressed by the sceptic, since it is a shortcoming that severely impairs the ability to make the correct risk-based decisions under uncertainty. Indeed, it could be argued that our government’s uncompromising pursuit of a carbon-free future is as a direct result of such a miscalculation. It is therefore a matter of great personal frustration that the publicising and addressing of this issue has not been a priority amongst professional and academic risk scientists. For too long now, climate scientists have been allowed to get away with professing a superior expertise in the evaluation and communication of risk and uncertainty, unchallenged by domain experts within the broader community of risk scientists.

Despite being something of an amateur when it comes to risk science, I have done what little I can by writing articles here that attempt to clarify the relevant technical issues. For example, I have challenged the IPCC’s concept of a ‘risk management framework’, given that it is predominantly focused upon psychological manipulation aimed at engineering compliance with policy. I have drawn attention to a profound and widespread failure within the climate science community to understand uncertainty’s philosophical framework and how this has resulted in an over-reliance on probability distributions when quantifying risk and uncertainty. I have taken a prominent communicator of climate science to task for advocating the view that gaps in knowledge are a layman’s misconception of what uncertainty is. I have warned of the important distinction to be made between risk and uncertainty aversions and what this means for those who advocate a precautionary approach. I have drawn attention to the relevance of ergodicity and have warned against the misuse of terminology such as ‘black swan’. And I have tried to point out how causal narratives are routinely oversimplified in the interest of promoting a ‘correct’ framing of the problem.¹

But most of all, I have been at pains to point out the dangers of using levels of expert consensus as a metric for uncertainty. In particular, I expressed concern that, when it came to issuing advice to the IPCC’s lead authors on how to standardise on the evaluation and communication of risk and uncertainty, the supposed IPCC experts dished up a set of guidelines that were so confused, ambiguous and internally incoherent that one had to conclude that any statements subsequently emanating from the IPCC regarding risk, uncertainty or confidence would have to be treated with considerable suspicion.

Be that as it may, I cannot hope to exercise the required levels of influence on my own. I have no academic standing to leverage and virtually no online following. It is for this reason that I was particularly gratified to see Dr Judith Curry publish a book that covers many of the themes you will have seen me address. Furthermore, it is even more gratifying to see that a highly-respected risk scientist, Dr Terje Aven, Professor of Risk Analysis and Risk Management at the University of Stavanger, Norway, has tweeted the following regarding Dr Curry’s book:

I am impressed by the way Curry has addressed important scientific issues related to climate change, and in particular uncertainty and risk…It is seldom to see climate scientists dealing with risk science issues in such a professional way, giving due credit to the scientific literature, summarizing and drawing conclusions on important climate topics.

He goes on to say:

Risk science knowledge provides many different concepts and perspectives, and being able to develop a holistic and consistent presentation based on this knowledge is not straightforward. But this is exactly what Curry has done. Climate Uncertainty and Risk provides a comprehensive exposition of risk and uncertainty issues related to climate change, based on contemporary risk science…[T]his book represents a very strong contribution to the scientific discourse on climate uncertainty and risk.

Given that Dr Curry has been accused by fellow climate scientists of failing to understand uncertainty,² it is interesting that she should be receiving such validation from a leading domain expert.

Moreover, an examination of Dr Aven’s own publication history makes it clear that he shares many of my concerns when it comes to the treatment of risk and uncertainty within the climate science community.³ Indeed, when he did his own review of the IPCC’s guidelines for lead authors on how to standardise on the evaluation and communication of risk and uncertainty, he came to the same conclusions that I had, making him, to my knowledge, the only high-profile risk scientist to have taken up the cause by pointing out the conceptual failings within the climate science community.⁴ Professor Aven’s concluding remarks say it all:

In this article, we have argued that the IPCC assessment reports fall short of a theoretically and conceptually convincing foundation when it comes to the treatment of risk and uncertainties…The important concepts of confidence and likelihood used in the IPCC documents remain too vague to be used consistently and meaningfully in practice.

That said, it is important to appreciate that Professor Aven is not a climate scientist and so reserves judgement regarding the significance of his criticisms:

The critical remarks on the treatment of uncertainty and risk should not be interpreted as an expression of skepticism toward the main insights from IPCC climate change reports or even misjudged as a critical position toward the major assumption of anthropogenic climate change. This is also not our main field of expertise. The main purpose of this article is to contribute to strengthening the quality of the complex and ambiguous assessment of future climate change by suggesting improvements in the analytic handling of risks and uncertainty. This can assist [the] IPCC in making its messages and recommendations more robust.

I would endorse that caveat. When I criticise the IPCC’s handling of risk and uncertainty I do not do so because I seek to challenge the scientific fundamentals of climate change. However, I do believe that policy-makers who are making decisions based upon a scientist’s statements of confidence and likelihood have a right to expect that those statements are not employing terminology that is ‘too vague to be used consistently and meaningfully in practice.’ Nor should it be too much to ask that they be working with a ‘theoretically and conceptually convincing foundation when it comes to the treatment of risk and uncertainties’. As Professor Aven says, when we speculate upon the future direction of the climate, and what to do about it, we are dealing with a complex and ambiguous assessment. Therefore, this is not so much about the science as it is about the making of risk-based decisions under uncertainty. If, as a result, you are going to propose a course of action that is likely to immiserate nations and destroy economies, I believe it behoves those responsible to at least master the concepts that lie at the heart of their deliberations. When Professor Aven writes of assisting the IPCC ‘in making its messages and recommendations more robust’ he should instead be referring to them being sufficiently safe and reliable. In my view, given the weaknesses within the theoretical and conceptual foundation used by the IPCC, the resulting messages and recommendations are far from that.

Footnotes:

[1] I could go on by mentioning my surprise that the IPCC should think that a ‘story telling’ approach to extreme weather event attribution could possibly be characterised as a method for analysing deep uncertainty, or that anyone could think of uncertainty as being ‘actionable knowledge’. There was also my article on Ellsberg’s paradox and how it leads to the need for robust decision-making, and my despair at seeing supposed experts fall for the transposed conditional.

[2] For example, James Annan seemed less than impressed with Dr Curry’s attempt to explain non-binary logic as applied to the question of anthropogenic attribution.

[3] Readers of this blog may also be interested to hear that I approached Professor Aven to seek his views on my Cliscep review of the IPCC’s Assessment Report 5, Working Group 3 (AR5 WG3): ‘Integrated Risk and Uncertainty Assessment of Climate Change Response Policies’. His response was terse but no less reassuring for that: “And that first article on IPCC was great”.

[4] That said, Aven’s paper cites a number of climate scientist reviews of the IPCC’s handling of risk and uncertainty, not all of which are fully supportive.