THE POLICY DEBATE with respect to anthropogenic climate-change typically revolves around the accuracy of models. Those who contend that models make accurate predictions argue for specific policies to stem the foreseen damaging effects; those who doubt their accuracy cite a lack of reliable evidence of harm to warrant policy action.

JC comment: Two recent essays of relevance here:

These two alternatives are not exhaustive. One can sidestep the “skepticism” of those who question existing climate-models, by framing risk in the most straightforward possible terms, at the global scale. That is, we should ask “what would the correct policy be if we had no reliable models?”

JC comment: The issue of ‘no reliable models’ was addressed in Driving in the Dark: Long-term strategies should be built not on “visions” of the future but instead on the premise that longer term predictions (that is, forecasts of situations years and decades out), however presently credible, will probably prove wrong. – Richard Danzig

We have only one planet. This fact radically constrains the kinds of risks that are appropriate to take at a large scale. Even a risk with a very low probability becomes unacceptable when it affects all of us – there is no reversing mistakes of that magnitude.

JC comment: This returns us to my previous essay on Taleb’s work Is climate change a ‘ruin’ problem? Excerpt:

In many ways, the risk of climate change is an aggregate of the risks faced by individual regions. The warming is not uniform over the globe, and with projected global warming, there are both ‘winners’ and ‘losers’ (see my Testimony). Another relevant question is whether a future ice age – occurring naturally – would be considered as ‘ruin’? The impacts of a future ice age are arguably more severe than doubling or even tripling CO2 (even if you believe IPCC projections). Not to mention that CO2 warming would delay a future ice age. I’m not really seeing AGW as a ‘ruin’ problem, i.e. a ‘catastrophe’. And finally the issue of ‘recovery’ is a time-scale issue (what is ‘forever’?) – e.g. the ice sheets in an ice age will eventually retreat. This whole issue of ‘ruin’ ties back to the issue of what actually constitutes ‘dangerous’ climate change. See these previous posts on the issue of ‘dangerous’:

Without any precise models, we can still reason that polluting or altering our environment significantly could put us in uncharted territory, with no statistical track- record and potentially large consequences. It is at the core of both scientific decision making and ancestral wisdom to take seriously absence of evidence when the consequences of an action can be large. And it is standard textbook decision theory that a policy should depend at least as much on uncertainty concerning the adverse consequences as it does on the known effects.

JC comment: The precautionary principle simply isn’t a good fit for a complex, wicked problem that isn’t a ‘ruin’ problem. From my post Permanent paradigm paralysis:

In their Wrong Trousers essay, Prins and Rayner argue that we have made the wrong cognitive choices in our attempts to define the problem of climate change, by relying on strategies that worked previously with ozone, sulphur emissions and nuclear bombs. While these issues may share some superficial similarities with the climate change problems, they are ‘tame’ problems (complicated, but with defined and achievable end-states), whereas climate change is ‘wicked’ (comprising open, complex and imperfectly understood systems). For wicked problems, effective policy requires profound integration of technical knowledge with understanding of social and natural systems. In a wicked problem, there is no end to causal chains in interacting open systems, and every wicked problem can be considered as a symptom of another problem; if we attempt to simplify the problem, we become risk becoming prisoners of our own assumptions.

Simply put, the current focus on CO2 emissions reductions risks having a massively expensive global solution that is more damaging to societies than the problem of climate change.

The precautionary principal is by no means the only decision analytic framework to use under conditions of deep uncertainty, see these previous posts: