Wednesday, December 08, 2004

The end of the World

As an astronomer you get used to thinking in the long term. A few million years is a relatively short time scale when you reguarly deal in time scales of billions of years, so when someone tells you something bad is going to happen in only a few hundred years, you tend to take notice. Astronomers are also used to thinking about global catastrophes. The impact of Comet Shoemaker-Levy 9 with Jupiter in 1994 made the threat of Near Earth Objects very plain, and since then some money at least has been directed towards the hunt for such objects. After all, what sensible species would watch a rock the size of a large mountain strike a nearby planet and then do absolutely nothing about it?

There are other possible extiction level events. A nearby supernovae could send a wave of lethal radiation towards us, stripping the protective ozone layer from our planet, indeed it has been suggested that this may have happened before. Closer to home, the eruption of a Supervolcano might make all our worrying about mankind's effect on the climate totally irrelevant.

CREDIT: British Antarctic Survey/C Gilbert, PA
Part of a massive tabular iceberg adrift in the Weddell Sea off the Antarctic peninsula. In Antarctica, the recent break-up of ice shelves has precipitated increased streaming of ice from much farther inland, which potentially represents the initiation of a phase of much more serious ice-sheet collapse.

We can do little about the most of the external threats to the continuation of our species, at least for now. Maybe in a few hundred years, if we get lucky enough to make it that far, then we will have the technology to address at least some of them. But Jan Zalasiewicz's recent article in The Guardian suggests we might not have those few hundred years.

I'd recommend people read it, it scared me badly, and like geologists, astronomers don't scare easily. We're used to thinking about the world coming to an end, and maybe you should be thinking about it as well.