Some years ago I argued that, although there were still many interesting questions left to be resolved, the scientific aspects of global warming were sufficiently clear that for policymaking purposes it was appropriate to move on to the question: “What shall we do about it?” And when we get there we are no longer (insofar as we ever were) in the realms of questions of atmospheric physics.

Then we have arrived in the realms of economics, of evaluating pros and cons, discounting risks and rewards and identifying incentives and behavioural feedbacks. And in my view the answer economics has given has always been very clear: our core strategy should be to adapt to climate change, not to attempt (futilely and expensively) to prevent it.

To believe a UK policy strategy of attempting to prevent climate change is better than a UK strategy of adapting to it, one must accept seven things – all but the first of which are unlikely:

The environmental impacts, after climate feedbacks, of CO2 release lie in the upper part of the mainstream range (i.e. in simple terms, one must be at least moderately pessimistic regarding the science). The low-end estimates (e.g. 1 degree rise over a century, similar to that in the 20th century) could be adapted to so trivially that there is nothing to discuss, whilst rises in the lower part of the range (up to about 2 degrees) have almost always, in serious economic analysis, been found to have costs of adaptation below those of mitigation. A globally coordinated strategy to prevent global warming is possible and would not create its own problems worse than the cure (e.g. it would not create authoritarian global policy instruments that risked falling into the hands of global tyrants; or would not risk setting off global cooling instead; etc.) Mitigation policies that would be implemented via globally coordinated strategy would be close to optimal (i.e. we would pursue the best strategies, not simply those easiest to agree upon or those that were most visible and easy to point to) The chances of “something turning up” as we go along, either in the way of some technical fix (some new invention or technique that allows CO2 to be cleaned up) or of some offsetting force (e.g. some other environmental event – volcanoes, sun, etc – that might trigger cooling) or some unforeseen balancing factor (e.g. the seas absorb all the extra atmospheric heat with little discernible other impact), is low Market forces (e.g. the natural evolution to new fuel sources, or new innovations funded by insurance companies) do not mitigate emissions and the effects thereof naturally and more effectively than regulatory-forcing. The biting impacts do not ultimately arise so far in the future that their discounted value today is trivial (e.g. it doesn’t turn out that there is no material impact for a century, but which point everyone is so rich that their resilience to climate change’s impacts is so high that there would be no point in us today, far poorer than folk in a century’s time, making sacrifices for them) Our ability to adapt, and to spread the costs of adaptation appropriately (e.g. wealthy countries in a century’s time providing assistance to poorer countries more affected by the impacts of climate change) is low

I believe it fairly clear that, aside from the first of these (about which debate continues), none of the criteria is likely to be met. Global coordination has already collapsed. Those policies that did have some international support were far from optimal. The chances of something turning up is high. It is very likely that market forces would, if allowed to, naturally mitigate or avoid a significant part of the effects. Biting impacts will almost certainly arise so far in the future that their discounted present value is small. And our ability to adapt will almost certainly be high.

Note that none of these points relies upon any denial that there is global warming or that human actions contribute materially to it. Note also that, although I mention point 1 (i.e. the possibility that actual warming will be towards the lower end of modelled projections) I do not rely upon it.

I have recently seen article after article urging that we should all agree that there is global warming and the debate should be about what to do about it. I agree, provided that “what to do about it?” includes the options “nothing” or “wait and adapt” or “start adapting now”. The mistake made in this discussion is to assume that “what to do about it” must mean “how to prevent it”. We are not going to prevent climate change, and it is far from obvious that the cost-benefit analysis of attempting to prevent climate change would be favourable even if we could.

Many scientists have started to write articles bewailing the supposed irrationality of the public in its resistance to climate change prevention policies. There is even a growing academic literature on the “psychology of climate change denial”, as if not wanting to mitigate climate change were a psychiatric pathology rather than a policy preference. Even if one accepted the most absurd “thermageddon”-type scare story view of climate change and its impacts, it would still not necessarily be irrational to reject policies to attempt to prevent it.

First, one might claim that such policies wouldn’t work – I could well believe that the volcano gods are angry and going to punish us for our impiety but at the same time deny that sacrificing a virgin to them at dawn is going to placate them; just because I accept your diagnosis of a problem that doesn’t mean I believe your solution will be effective.

Second, there is nothing irrational about discounting the future. Folk might prefer to “live fast and die young”. That’s not an error or a psychiatric disorder; it’s a preference.

In fact, of course, no-one serious is talking about any adult alive today experiencing anything more than modest impacts from climate change. The serious impacts are forecast to be experienced by folk in a century’s time. So when we ask folk today to make sacrifices (expensive energy etc) to mitigate climate change, we are asking them to lose out themselves so that their children’s children’s children, in a century’s time, will gain. But our children’s children’s children will be rich beyond our wildest dreams of avarice, as we ourselves are rich beyond the comprehension of folk one hundred years ago.

If folk today, struggling in tough economic times, do not want to make sacrifices so that those fabulously richer than them, in 100 years’ time, can be richer still that is not irrational. That is a policy choice – and by no means an obviously selfish or silly one.