DON鈥橳 read this if you鈥檙e a worrier. This year we discovered that life on Earth is more precarious than we thought, and not just because we鈥檙e doing a good job of destroying the environment and devising fresh ways to kill en masse (see 鈥淒espite all the talk, real change is as elusive as ever鈥� and 鈥淏ioterror takes centre stage鈥�).
While astronomers downgraded their estimate of how often to expect a city-levelling asteroid strike 鈥� from once every 250 years to once a millennium 鈥� geologists claimed this was a mistake. Their evidence, which includes car-sized rocks tossed over 40-metre cliffs in Australia, suggests that meteorites capable of triggering massive tsunamis can fall thick and fast when Earth passes through the debris from a comet. But this isn鈥檛 due until 3000. Phew.
In the meantime, though, even a small strike could spark a disaster. Neither Pakistan nor India can rapidly distinguish between a nuclear attack and a 5-metre asteroid exploding as it enters the atmosphere鈥�
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Volcano experts were also in on the apocalyptic action. They claimed that supereruptions capable of wiping out over a billion people happen every 50,000 years or so, far more often than asteroid strikes of similar destructive power.
It wasn鈥檛 all doom and gloom. Taiwan has set up an automated system that can give some islanders a 10 to 25-second warning of an impending earthquake. That鈥檚 enough time to shut gas lines and tell surgeons to put down their scalpels. The trick is to select data from just a few seismographs, allowing the computer to pinpoint the quake鈥檚 epicentre so fast that warnings can be sent to places over 50 kilometres away before the shock waves hit them.
And astronomers have now catalogued the orbits of over 600 of the 1100 or so rogue asteroids. But spotting a planet-buster won鈥檛 be much use unless we can alter its course. Developing the capability to deflect one might win space agencies far more support than the International Space Station, rendered impotent by budget cuts.