The folk at the Royal Swedish Academy of Sciences are nothing if not cautious when it comes to awarding prizes for scientific achievement. And who could blame them? There would surely be nothing more embarrassing than to award a prize for a scientific breakthrough that was subsequently proven to be a false alarm. A case in point would be the caution shown towards Albert Einstein. Despite his annus mirabilis being 1905, it wasn’t until 1921 that the Academy felt confident enough to bestow Nordic recognition; and even then they still couldn’t bring themselves to explicitly mention relativity in the citation. So it comes as no great surprise to see how tardy they were in acknowledging the seminal work undertaken in the field of non-linear dynamics. And when that time finally came, in 1977, it was equally of no great surprise to see that they singled out Ilya Prigogine for their attentions. After all it was he who had pioneered the subject of non-equilibrium thermodynamics, thereby establishing the fundamentals of dissipative structures. What was surprising, however, was the omission of other, equally worthy candidates within the field. Take, for example, a household name such as Benoit Mandlebrot, mathematician, aerodynamicist and father of fractal geometry. Or how about Edward Lorenz, the American mathematician and meteorologist who gave his name to the iconic Lorenz Attractor and coined the term ‘butterfly effect’?

So when the Academy next chose to honour physicists that had made major contributions to the field, one might have thought that they would have taken the opportunity to correct such an obvious oversight. But no, they didn’t. When it came to the 2021 awards, they chose instead to share the honour between Giorgio Parisi, Syukuro Manabe and Klaus Hasselmann. This rather invites the question as to why these gentlemen, magnificent though their work might be, were picked out on this occasion.

Throwing caution to the chaotic turbulence

The first clue to answering this question can be found in the citation. According to the Academy, the award was given for ‘groundbreaking contributions to our understanding of complex systems’. The emphasis here was therefore not on the propensity for seemingly ordered systems to break down into chaotic behaviour that defies predictability (à la the butterfly effect), but for the propensity for order to emerge from behaviours that are ostensibly chaotic. It is this capacity for self-organisation that characterises the complex system. Chaos implies unpredictability despite a firm understanding of the underlying laws. Complexity implies predictability, provided one is looking at particular length- and time-scales. This important distinction becomes even clearer when one looks at how the citation reads with regard to the three recipients.

In the case of Parisi, the award is for ‘the discovery of the interplay of disorder and fluctuations in physical systems from atomic to planetary scales’. Specifically, the Academy seems to have been impressed by his work on so-called spin glasses – magnetic states characterised by randomness that can nevertheless support complex metastable structures.

However, it is when one turns to the other half of the award, shared between Manabe and Hasselmann, that one not only sees how the importance of predictability applies, but also how the award represents something of a Trojan horse. For here it’s not just the predictability of an ostensibly chaotic system that is at stake, it is the credibility of the climate science modelling community. And we all know how important that has become politically (no wonder that Lorenz has missed out again with his warnings of unpredictability). According to the Academy, Manabe’s and Hasselmann’s prizeworthy contributions were the ‘physical modelling of Earth’s climate, quantifying variability and reliably predicting global warming.’

Excuse me, what was that again? Reliably predicting global warming?

Look, I’ll be the first to admit that understanding the physics of the underlying variability is a necessity if one is to tackle the thorny problem of predicting how the Earth’s climate is likely to develop in the face of a number of forcings. I get it that Manabe was a ground breaker when it comes to the idea that such a system could be modelled mathematically with the support of computers. Nor do I deny his early successes in matching observations. I also concede that Hasselmann did a good job of demonstrating how weather forecasts can be impossible beyond five days and yet the climate can, at least in principle, be predicted many years in advance. (This apparent paradox is solved when one considers that there are dissipative factors such as the thermal inertia of the Earth’s oceans to be taken into account. As a result, stochastic integration transforms the white noise of weather variability into the red noise of climatic change. I could add that it isn’t really such a surprising result, given that one can reliably predict that next winter will be colder than last summer, without knowing what will happen on Christmas Day).

However, neither the advancements due to Manabe nor Hasselmann are sufficient to place oneself in the situation of being able to ‘reliably predict global warming’. For that, one has to be able to tackle the significant systemic uncertainties that are still inherent within the climate models. The epistemic uncertainties regarding aleatoric uncertainties may have been reduced, courtesy of these two gentlemen, but the normally conservative Royal Swedish Academy of Sciences surely overreaches when it suggests that the epistemic uncertainties have been vanquished by Manabe and Hasselmann to such an extent that predictability is now to be expected. The Earth’s climate system is not a spin glass, for which the spin glass model (singular) can be used to predict macro behaviour based upon aleatoric analysis of micro behaviour. It is, instead, an open, driven, nonlinear system that is far from equilibrium and far from fully understood. Predictions are formed from model ensembles in which the outcome uncertainties have much more to do with the epistemic than the aleatoric.

So why has the erstwhile Academy of caution chosen to be so gung-ho on this occasion? Why, contrary to the truth, are they citing work as though it has banished unpredictability? It is at this point in proceedings that I have to put on my evil, conspiracist climate denier’s tin foil hat.

“And the award goes to – climate science!”

As I have previously maintained, albeit in a different context, there is a huge difference between necessity and sufficiency when it comes to forming an explanation. So it seems at first odd that the Royal Swedish Academy of sciences, of all people, should be writing citations that appear to ignore the distinction. Odd, that is, until one reflects upon the political importance of the award.

The Swedish Academy does, of course, have history when it comes to endorsing the efforts of the climate concerned. Back in 2007 they famously awarded a Peace Prize to be shared between the IPCC and Al Gore. Given the political nature of this award, one could not take this as an endorsement of the science; rather it was a recognition of political effort. Indeed, the very fact that the IPCC was sharing the podium with Al Gore emphasises that the Academy saw the IPCC as a political body rather than a scientific one. It was high time, therefore, that the Academy declared its full endorsement of the scientific efforts upon which IPCC politics are founded. Recognising that much of the credibility behind the science rested upon the credibility of climate modelling and the understanding of complex systems, the choice of recipients on this occasion seems perfectly natural. But let us not be under any illusions here; it isn’t Manabe’s and Hasselmann’s reputations that concerned the Academy this year, it was the reputation of climate science in general. And just to ram home the point that the Academy considered climate modelling to be rock-solid science, the prize was to be shared with a luminary from the field of condensed matter physics. Representatives of the Academy have been at pains to point out the overarching theme of complexity theory, but I am more impressed by the differences. For example, nowhere within condensed matter physics do we see a key parameter that is known only within a wide uncertainty range that has changed little in 40 years (I speak, of course, of ECS). And nowhere within condensed matter physics will you find the widespread habit of treating epistemic uncertainty as if it were aleatoric, resulting in a focus on the multi-model mean of climate model ensembles that, according to climate scientist Theodore G. Shepherd, ‘has no epistemological justification.’

None of these shortcomings get a mention in the Academy’s citation – there is only the reference to reliable prediction. Which is a shame. But we climate denying reprobates have at least one small crumb of comfort. At least we didn’t wake up the other day to read the following:

“The 2021 Nobel Prize for physics has been awarded to Michael Mann for his groundbreaking application of dodgy statistics and cherry picking to overturn a wealth of cultural and historical references to a Medieval Warm Period”.

Now that would have been a step too far, and I thank God that even the Royal Swedish Academy of Sciences knew it.