Climate Change and Uncertainty

Probably the main reason why we cannot agree on what to do about anthropogenic climate change is that we seem not to understand the inherent, deep uncertainty of the problem. A few days ago I wrote a more general post about the importance of uncertainty in decision-making, so I won’t repeat the argumentation here. I just would like to focus on the specific problem of uncertainty in climate policy, and present a possible approach.

The climatic system of the Earth is a highly complex one. This makes concrete predictions about how it will behave in the future very fuzzy. Furthermore, the anthropogenically induced changes in this system are something completely unprecedented – above all, they are faster and its source is different than anything we know from the (very far) past. Since human knowledge arises from experience, we cannot be able to predict what will happen with the climate of our planet – we just can make guesses, seek for some micro-evidence, extrapolate… But all this is necessarily coupled with a high level of uncertainty which cannot be overcome.

Clearly, we cannot wait for ultimate evidence (i.e., the next climate equilibrium) – we have to decide now what to do about climate change. The decision-making process can be supported by focusing on two extreme alternatives – you may say, the lower and the higher bound of what may come.

The first alternative is the following: assume that we engage heavily in climate change mitigation and adaptation to the changes already under way. We spend billions of dollars each year on cap’n’trade programmes, investments in “clean” energies, funds to preserve forests (e.g., the Yasuní-ITT initiative), energy efficiency, research and development in new, “green” technologies etc. Now suppose that, other than some economists and activists claim, this will really cost much – jobs in traditional, carbon-heavy industries will be destroyed without enough compensation from the “green” industries; budget deficits will rise; there will not be enough money left to invest in other important purposes (e.g., tackling AIDS). Now imagine that after our having done all this, our descendants will face a world made poorer, and without much damage from climate change – the lower bound of climatologists’ projections was “true”. No catastrophe destroys Earth, humanity’s livelihood isn’t significantly damaged. You will admit that this is not a nice picture – neither for us, nor for our grand-grand-children and those who follow.

Now consider the second alternative: assume that we proceed with business-as-usual politics. After having sunk some more climate conferences, we decide to ignore all the “greens” and “ecos” (or however you call them). The fear of losing money, of unnecessarily investing billions in technologies nobody really needs, of taking our development ministries the money they otherwise would use to pretend they’re helping the poor – all this turns out to have more weight in our considerations than the stories told by Green parties, Al Gore and Greenpeace. But then, when it is already too late for us to change our minds, the climate change comes striking – it turns out that even Jim Hansen was underestimating the climate sensitivity; shortly: we face a catastrophe. Our livelihood gets utterly destroyed. Humanity, at least as we’ve known it, vanishes.

It is more probable than not that neither the first nor the second alternative will come upon us. It is far more probable that we are going to find ourselves somewhere in between. But the fact is: we cannot know. We cannot ask the Black Swan. As improbable as they seem, both alternatives are possible.

We have to choose. Postponing the decision is also a decision. Unpleasant as it may be for us humans, accustomed to dealing with at least (seemingly) Gaussian probability distributions, the uncertainty won’t become significantly smaller.

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