A popular new paradigm for the nature of change pertains more to the social and political worlds than it does to the physical one.
Rarely since Catch 22 has a book title made its mark on the language in such a way as The Tipping Point. The author, Malcolm Gladwell, made no claim to have invented the term, but his thought-provoking book brought the idea into common parlance. Since then, the view that incremental changes in a cause can suddenly produce a much larger effect has entered common currency. It is now being ever more frequently deployed in the debate about the world's climate.
In some respects, this is old wine in new bottles. For almost as long as people have been worrying about anthropogenic climate change, there have been warnings that, although the build-up of greenhouse gases may be slow and gradual, the effects they will have on the system need not be. The physical, chemical and biological responses that turn greenhouse gases into climate change are complex and subtle, and capable of responses that are surprisingly disproportionate. There are thresholds beyond which the past response of the system no longer predicts the future, and there are positive feedbacks through which change can feed on itself. All these possibilities are now being discussed under the rubric of tipping points.
It is reasonable to worry about such things, but there are three dangers attendant on focusing humanity's response to the climate crisis too much on tipping points. The first is the uncertainty of the science; the second is the tendency of such an emphasis to distort our responses; the third is the danger of fatalism.
Anyone claiming to know for sure when a particular tipping point will be reached should be treated with suspicion.
The models through which our understanding of the climate system are channelled into assessments of how it might behave in the future are impressive by the standards of human investigation, but crude with respect to the details of the Earth system. All sorts of phenomena, from the formation of clouds to the respiration of soils, are hard to capture accurately, and it is on such details that an understanding of possible tipping points depends (see page 802). Anyone claiming to know for sure when a particular tipping point will be reached should be treated with suspicion — and so must anyone who suggests that no tipping point will ever be reached.
The second problem is that an emphasis on tipping points not yet reached increases the focus on the future. Such an increase tips the balance away from adapting to climate change and in favour of trying to avoid it. A rational response to the challenge of the twenty-first century's climate is to do both: to reduce the rate at which greenhouse gases force climate change, but at the same time build up the ability to cope with adverse climates.
The third issue is that tipping points can induce fatalism. The concept may encourage the belief that a complete solution is the only worthwhile one, as any other course may allow the climate system to tumble past the crucial threshold. This sort of all-or-nothing approach is already over-stressed in climate policy by the Framework Convention on Climate Change, which calls for the complete avoidance of dangerous anthropogenic climate change, rather than the more reasonable and more feasible goal of minimizing and controlling it.
The concept of the tipping point is, in fact, more pertinent to the climate crisis in the social sphere than in the physical world. The strength of Gladwell's book lies in its reasoned illustrations of the ways in which beliefs and behaviours change, and the rules and contexts that govern that change. It is possible to make people change their minds and behaviours, and for those changes to spread like a contagion. “Look at the world around you,” Gladwell argues. “It may seem like an immovable, implacable place. It is not. With the slightest push — in just the right place — it can be tipped.”
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Reaching a tipping point. Nature 441, 785 (2006). https://doi.org/10.1038/441785a