Uncertainty is not your friend (?)

by Judith Curry

It is very clear that uncertainty is no one’s friend. We have seen that greater uncertainty about the evolution of the climate should give us even greater cause for concern. We have seen that all other things being equal, greater uncertainty means that things could be worse than we thought. We have also seen that greater uncertainty means that the expected damages from climate change will necessarily be greater than anticipated, and that the allowance we must make for sea level rise will also be greater than anticipated. All of those results arise from simple mathematics, and we do not even have to resort to any economic modelling to understand how greater uncertainty translates into greater risk. – Stefan Lewandowsky

Stefan Lewandowsky has a series of three posts at the blog Shaping Tomorrow’s World:

• Uncertainty is not your friend
• The inescapable implication of uncertainty
• Climate uncertainty and emission cuts

Read the complete articles to get the details of his arguments.  Here I present his main points.

The main point from Uncertainty is not your friend:

In a nutshell, the logic of this position can be condensed to “there is so much uncertainty that I am certain there isn’t a problem.” How logical is this position? Can we conclude from the existence of uncertainty that there certainly is no problem?

This conclusion appears inadvisable for a number of reasons that will be examined in this series of three posts. To foreshadow briefly, there are three reasons why uncertainty should not be taken as a reason for inaction on climate change:

Uncertainty should make us worry more than certainty, because uncertainty means that things can be worse than our best guess. Today’s post expands on this point below, by showing that in the case of climate change, uncertainty is asymmetrical and things are more likely to be worse, rather than better, than expected.

Main point from the Inescapable implication of uncertainty:

The first conclusion about the climate system therefore has to be that the greater the uncertainty, the greater the potential for catastrophe.

Greater uncertainty means things can be worse than you think. And greater uncertainty means you’ll pay more for the damages arising from climate change than if there were less uncertainty. In fact, you may end up paying much more than anticipated.

Main point from Climate uncertainty and emission cuts (well this one defies a simple summary):

First, we need to realize that to stabilize atmospheric concentrations of greenhouse gases, our current emissions have to tend towards zero. Just cutting 5% or 10% as suggested by political leaders (at best) will achieve nothing.

It is clear that all lines tend towards zero sooner or later, and it is clear that the more we want to limit the budget, the steeper and the sooner the required emission cuts. 

So not only does greater uncertainty put the worst-case scenario into a very bad spot, it also increases the likelihood of that worst-case scenario being true.

So no, uncertainty is no one’s friend, whether we talk about damages from climate change or the costs of mitigation. There is no escaping those simple mathematical facts.

There is only one way to escape that uncertainty: Mitigation. Now.

Ben Pile’s critique

Ben Pile has written a lengthy critique, entitled:  Turning Uncertainty into Certainty:  Reinventing the Precautionary Principle.  Some excerpts:

As previous posts have pointed out, the issue is not whose friend the precaution principle is — indeed, the point was made that the precautionary principle might apply to the precautionary principle. Thus, precaution may leave us in a dizzy spin of infinite regress. The issue for ‘denialists’ is instead that the application of the precautionary principle passes weak theoretical risk off as certainty; it turns possibility into story lines, about which ‘something must be done’.

We have seen that greater uncertainty about the evolution of the climate should give us even greater cause for concern.

In other words, ‘the less we know, the more we should worry’. This has a curious implication. Whereas Oreskes had claimed that science had always been certain — that an unequivocal consensus had always existed — Lewandowsky must now claim that the consensus had not advanced its understanding of the climate: that we don’t know more than we did. And indeed, this reflects an ideological presupposition of environmentalism: that progress is itself a problem. For if certainty was actually achievable — if the parameters of climate change were actually understood — then ‘tackling climate change’ would become a straightforward technical problem. Instead, policies intended to tackle it are founded on the idea that the possible impacts of climate change are uncertain, precisely in order to head off any possibility of a solution that is not mitigation. In other words, if you know what kind of problem you are facing, then you deprive those who have made the undefined problem central to their perspective and their arguments about the urgency of their cause.  The urgency of the problem is owed only to the fact that we don’t know what kind of problem it is.

We have also seen that greater uncertainty means that the expected damages from climate change will necessarily be greater than anticipated…

This is an extraordinary claim indeed, which requires some unpacking. This part of the sentence puts the degree of uncertainty into a necessary (i.e. it cannot be otherwise) relationship with what we have anticipated, and the outcome of events. The condition of uncertainty itself multiplies the anticipated result, to yield an impact of greater magnitude. This is an absurd claim, because the condition of uncertainty has no bearing on things. If you’re unsure about what the result of a throw of a dice will be, but you anticipate that it will not be the number you want it to be (the odds are just 1 in 6 that it is, so it’s a good bet that it isn’t), your uncertainty does not reach out to the dice to prevent it turning the face with your number on it upwards.

But that is the implication of the term ‘necessarily’ in the sentence. So let’s mediate it, to see if it makes any more sense: ‘greater uncertainty means that the expected damages from climate change will necessarily may possibly be greater than anticipated’. 

All of those results arise from simple mathematics, and we do not even have to resort to any economic modelling to understand how greater uncertainty translates into greater risk.

Uncertainty has no relation to actual risk. The degree of risk is the same, no matter what the degree of certainty is. To say otherwise, is to say that the world is moved by nothing other than the confidence we have in our thoughts, and that I could will a dice to produce a 6 on each throw, merely by being sufficiently confident in the outcome: a Disney version of reality. Even the best sense we can make of his claim — that uncertainty implies the underestimation of risks — is a nonsense, because we know that it is possible to over-estimate risk, even in the face of uncertainty. And we have precedents: the Y2K bug; BSE; flu pandemics of recent years; acid rain; ozone depletion; and the entire torrent of turgid crap produced by Malthusians such as Paul Ehrlich over the last half century. 

The precautionary principle — risk analysis without numbers, and without a sense of proportion — gives greater weight to speculation than to knowledge. That is the nature of the politics of fear: you can’t rule something out, so in order to survive, you have to assume that anything you can speculate about is actually the case, and act accordingly. In the wake of criticism of the precautionary principle, environmentalists and those invested in the environmental agenda attempted to distance themselves from it, to emphasise certainty instead: the unequivocal consensus that ‘climate change is happening’. But the precautionary principle did not go away. It took on a new form, and lurked in the background. Rather than saying that the risks of climate change were beyond estimation, environmentalists invented a horizon of uncertainty: the limit of 2 degrees, beyond which lay ‘dangerous climate change’. But this limit was intangible. It wasn’t detected by science; it was invented to meet the needs of policy-makers. It mediated some of the excesses of the precautionary principle by reasoning that we know more about what will happen before 2 degrees of warming than what will happen following it.

But hiding the precautionary principle from environmentalism’s critics concealed it also from the environmentalists. They too forgot the ground on which their perspectives were formed. And now we see in Lewandowsky’s silly posts that the ugly creature wants to crawl back out of the hole it has been buried in. Lewandowsky’s posts will, by themselves, likely achieve no great influence, but what this shows is the irrepressible, irrational and incoherent nature of environmentalism. Environmentalists will continue to be divided by the precautionary principle as it continues to embarrass them and their claim to be grounded in science and reason. The precautionary principle will be reformulated and hidden again, and then reinvented,ad nauseum, long after environmentalism’s demise.

JC note:  the comments on Pile’s thread are worth reading.