The Last Word
Robert Matthews on why natural disasters don’t worry us more
HUMANITY OUGHT TO WISE UP ON THE LONG-TERM RISKS
hat would you think if a nuclear-tipped missile zoomed through space and nearly hit a satellite or two? That’s pretty close to what actually happened on 12 October last year – except that the ‘missile’ was under no one’s control.
Travelling at over 25,000 km/h, the housesized chunk of rock known as asteroid 2012 TC4 packed the punch of a few dozen atomic bombs as it flew overhead, at a similar altitude to many communications satellites. Yet after a bit of media coverage, the event soon went the way of all such ‘cosmic close shave’ stories, and disappeared off the news radar entirely.
Even when one of these objects actually does make it through the atmosphere – as one did over Chelyabinsk, Russia in 2013, injuring over 1,000 people – we all soon forget about it. But are we being too complacent? Many scientists argue that we are, and they claim to have evidence to prove it.
The trouble is, that evidence isn’t very compelling. Exhibit A is that the chances of dying in an asteroid impact that trashes the planet are around one in 75,000 – that’s double the risk of being killed by lightning. But wait, that can’t be right, surely? After all, the last time the Earth got totalled was around 65 million years ago, when the dinosaurs were wiped out.
The explanation lies in the fact that this risk depends on more than just how frequent the event is. While massive asteroid impacts are far rarer than lightning strikes, the likely death toll is millions of times higher – leading to that surprisingly high final risk figure.
Multiplying the frequency of the event by its consequences has long been deemed the only scientific way to make decisions about risk – and the theory behind this is pretty solid. But as a way of getting people –and politicians – to take risks of natural disasters seriously, it doesn’t really work.
That’s because the formula is only really helpful for deciding how best to protect the whole of