Level of risk = probability x impact

We fret about familiar risks – air crashes, carcinogens in food, low radiation doses, etc – and they’re all intensively studied. But we’re in denial about some emergent threats – the potential downsides of fast-developing new technologies and the risk of crossing environmental ‘tipping points’. These may seem improbable, but in our interconnected world, their consequences could cascade globally, causing such devastation that even one such incident would be too many. These potentially catastrophic threats surely deserve expert analysis. It’s crucial to assess which can be dismissed firmly as science fiction, and which could conceivably become real; to consider how to enhance resilience against the more credible ones; and to guard against technological developments that could run out of control. This topic should be higher on the international agenda. It’s a wise mantra that ‘The unfamiliar is not the same as the improbable’. And that’s why the topics addressed in these pages are so timely and deserve to be widely read.

It’s crucial to assess which risks can be dismissed firmly as science fiction, and which could conceivably become real.

Martin Rees

UK Astronomer Royal, and Co-founder, Cambridge Centre for the Study of Existential Risk