Book Review. Positive Tipping Points: How to Fix the Climate Crisis

Positive Tipping Points: How to Fix the Climate Crisis

By Tim Lenton

Simon Maxwell

Tim Lenton is an earth system modeller who has written a book applying his pioneering ideas about the physics of climate tipping points to the social and economic response to climate change. That is ‘brave’ – not quite in the civil servant sense when they tell ministers they are being brave when they really mean foolhardy, but certainly on the bold side of ambitious. You won’t find me writing about salt levels in ocean currents or the thawing of the tundra.

Does it work? Honestly, and to my mind, there are risks in this way of structuring the argument. But never mind, the book is not just brave, but readable, informative, stimulating and hopeful. The key lesson is that there is lots to do, and we had better get on with it, as purposively as we can.

Lenton spends about a third of the book on home territory, so to speak, summarizing the science of global warming and describing sixteen potential tipping points. Before that, we are introduced to the concept of the ‘tipping point’. And afterwards, in Part 2, we turn to what needs to be done, on everything from building social pressure to accelerating the adoption of wind power or electric cars.

The climate science need not detain us here, though Lenton has some interesting insights into the temperature ranges at which human societies flourish – about 13 degrees C on average, with a subsidiary peak in monsoonal climates at 25-26 degrees: life becomes  - is becoming - much harder away from the peaks or if the ranges shift. He also has sobering things to say about the risk of tipping point ‘cascades . . . or in the worst case, ‘domino dynamics’ where tipping one thing inevitably tips another and another.’ If this were to happen, Lenton says, ‘we would really have lost control of climate change’. An example is the melting of the Greenland ice sheet, which would tip the Atlantic overturning circulation, which would in turn threaten the West African monsoon, the West Antarctic ice sheet and parts of the East Antarctic ice sheet.

So far, so, mostly, familiar. What is important to understand, though, is the morphology of a tipping point. This is the movement from one more-or-less stable equilibrium to another - for example from sitting quietly on a chair through leaning backwards and falling noisily onto the floor. Two equilibria, separated by, in this case, somewhat reckless activity. Another example is the transition from life to death. In all such cases, including with respect to climate, the transition is restricted by ‘damping feedback’ but accelerated by ‘reinforcing feedback’. In the case of falling backwards on a chair, gravity helps in the early stages, tending to bring the chair back to its normal position, but gradually reverses until it accelerates the fall. An important hint that a tipping point may be approaching is if the damping feedback begins to taper off, and when a system takes longer to return to its original state.

When we come to the social and economic spheres, Lenton identifies actual or potential tipping points, some related to climate. Votes for women is one example. The ban on smoking in public places is another. Norway adopting electric vehicles is a third. Greta Thunberg mobilising public opinion is a fourth. And there is a host of incipient examples in the field of climate action: renewable energy, including wind, solar and green hydrogen, green ammonia for fertilizer, green steel, sustainable aviation fuel, regenerative farming, reforestation, dietary choices.

What turns incipient examples into actual tipping points and reinforcing cascades? Lenton cites ‘deeply committed individuals, forming tightly-knit groups . . . Government policy and regulation . . disruptive technical innovation . . . social learning and contagion . . .’ He celebrates his own suffragette great aunt, Lilian Lenton, who set out to burn down two buildings a week to draw attention to her cause and was arrested multiple times. He celebrates the Norwegian pop stars who used their fame to kick-start the adoption of EVs in Norway. He celebrates Extinction Rebellion. He praises German subsidies which spurred the global spread of solar PV. And he makes much of Wright’s Law, the learning-by-doing and economies of scale, which drive down production costs as output increases. All these increase the probability and irreversibility of tipping points: ‘once uptake of a new behaviour or technology has passed a tipping point to become self-propelling, while it may be slowed, it is hard to stop’.

Being ‘self-propelling’ and  ‘hard to stop’ is at the heart of the argument for using the term ‘tipping points’. I read the book on a Kindle. There are 6 mentions in the book of ‘hard to stop’, 35 mentions of variations on ‘hard-to-reverse’, 48 mentions of self-propelling, and 28 mentions of the term ‘irreversible’ or ‘irreversibly’.

This takes some thinking about. It is easy to see that some transitions are unlikely to be reversed: for example, it seems unlikely that we will again see horse-drawn carriages dominating road traffic in major cities. But there are others, maybe especially in the social sphere, where the pendulum could swing the other way. The opposition to net zero is having something of a moment, and not just in the US. Insurers and banks are abandoning climate commitments. Artificial meat is also under threat as the risk of ultra-processed food becomes better known.

Lenton himself recognizes the risk of reversal: ‘Of course, policy can waver with a changing political tide. Currently, there are plenty of reasons for pessimism, including social polarization, rising inequalities, conflicts and wars. Some populist politicians, parts of the media and other vested interests are  . . . (trying) to damp change towards green alternatives’. But change is ‘hard to stop’. Maybe. The latest Production Gap Report says that governments are planning more fossil fuel production in coming decades than before, and that this will put climate goals beyond reach.

But does irreversibility really matter? And do we really need to talk of tipping points as an organizing principle, when we have large literatures, both general and climate-specific on ‘transition’, ‘transformation’ or just plain ‘innovation’? Lenton references the innovation S-curve, specifically the work of Everett Rogers, that staple of agricultural economics and rural development courses, with a slow start by early adopters, then mass adoption, then a tailing off as laggards catch up on the way to eventual saturation. But we could also look at the work of statistics professor Oliver Johnson on the need to understand exponential rather than linear progression, for example in the spread of viruses; or the comprehensive work by Vaclav Smil on growth, specifically the ubiquity of sigmoid curves of different types. All this is understood in the climate field, for example in detailed research by Niklas Hohne and others for the UN Environment Emissions Gap Report on S-shaped sectoral transformations. There may be limited circumstances in which irreversibility is the crucial element, and it probably does little harm to popularise the term ‘tipping point’, but there are risks.

Specifically, focusing on the drivers of tipping points may ignore literatures on other drivers, associated with transition or transformation.

Lenton has a pretty good list of drivers, as noted. He could have drawn more on the core literature on tipping points. For example, Malcolm Gladwell, who is cited in the book, has a chapter in The Tipping Point on how ideas spread, on the different roles of connectors, mavens (well-connected experts) and salesmen. He talks about the importance of ‘stickiness’. And he emphasizes the need for constant testing and evaluation. ‘To make sense of social epidemics’, he says, ‘we must first understand that human communication has its own set of very unusual and counterintuitive rules’.   In his more recent book, The Revenge of the Tipping Point, he introduces new concepts: the overstory, the super-spreader, and the idea of group proportions.

But, of course, a wider perspective than ‘tipping points’ opens the floodgates on everything the social sciences can contribute to understanding and accelerating transformation. Just glancing at my bookshelf: Mariana Mazzucato on the entrepreneurial state and mission-led innovation, Chip and Dan Heath on stickiness, Duncan Green for Civil Society Organisations on How Change Happens, Diane Stone on policy entrepreneurship and think-tanks, and a stack of books on climate action, including Scoones, Leach and Newell on The Politics of Green Transformations, and our own work in the Climate and Development Knowledge Network (CDKN) on Mainstreaming Climate Compatible Development.

We need all these insights, and more. Tim Lenton is right about the urgency of climate action. He makes a valuable contribution. He encourages us to think about all the different ways in which we can work together to accelerate the response.

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Simon Maxwell is Co-Chair of Climate:Change

Perspective pieces are the responsibility of the authors, and do not commit Climate:Change in any way.