WHY DON’T NATURAL DISASTERS WORRY US MORE?
Humanity ought to wise up on the long-term risks
What 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 this 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 1 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 humanity for the rest of eternity. But Joe Public – and especially Sir Joseph Politician – tend to have rather more short-term concerns, such as living long enough to see their kids grow up, or getting re-elected. For them, that is perfectly rational, too. So telling them they’re wrong to ignore risks on timescales so vast they’ll probably never experience them isn’t going to win them over. Cosmic catastrophes, which typically have timescales of centuries and more, run straight into this timescale problem – which is probably why few people outside academia worry about them. But natural disasters on much shorter timescales can still engender indifference. From California’s San Andreas fault to the slopes of Mount Vesuvius, it’s clear that millions of people are quite capable of pondering the risks of living on the sites of far more frequent natural catastrophes and deciding they’ll probably be okay. So what kind of timescale do people take seriously when assessing such risks? Judging by the response of those living in hurricane zones, it takes less than a generation – around 20 years or so – for people to park their concerns about a repeat of a previous disaster. That’s far shorter than the average ‘return period’ of most forms of natural disaster, such as earthquakes, volcanic eruptions or Category 5 hurricanes. In one sense, all of this bears witness to the astonishing resilience of the human spirit. But it also highlights a critical limit to human rationality – and a major challenge to those seeking to protect humanity from long-term disaster. Unless they can find some way of circumventing the timescale problem, their pleas for action are likely to be greeted by the classic response of each new generation to the dire warnings of their elders: “Yeah, whatever…”.
“IT TAKES AROUND 20 YEARS FOR PEOPLE TO PARK THEIR CONCERNS ABOUT A REPEAT OF A PREVIOUS DISASTER”