When you insure your house you don’t care about the most likely scenario (i.e. that your house won’t burn down), you care about the remote possibility that it might. It’s not the likelihood of that tail risk that determines what you spend on insurance, but the ruinous consequences that such an outcome would have on your life.

Weitzman argued that this is how we should think about the economics of climate change – as a kind of planetary fire insurance.

It’s a powerful analogy, all the more so when one considers that, unlike house fires, for which we have a firm basis of evidence on which calculate the risk of a particular house burning down, there’s still a lot we don’t know about the risks of climate change.

The global climate is a vastly complex system which we’re messing about with by burning millions of years worth of fossil fuel deposits in a geological blink of an eye. We still don’t know what the full consequences of this interference will be.

The foolish response to this lack of knowledge, is to carry on regardless until we have further information. The wise response is to see what we don’t know as a spur to action not an excuse for complacency – especially when it comes to the only planet that we have to live on.

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Peter Franklin is Associate Editor of UnHerd. He was previously a policy advisor and speechwriter on environmental and social issues.

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