Thursday, August 19, 2010

Bye Bye Birdie

We've all heard about global warming likely caused by human activity, but lurking in the background is something we're probably also aware of - the accelerating pace of species extinction.

For the first time, I've seen some impressive numbers to back it up. For instance, how do current extinction rates compare with other great extinctions?

From the latest Scientific American:

The biggie - the Permian-Triassic Extinction - wiped out up to 96 percent of species around at the time. The event last some 1 million years, so the rate of extinction was 9.6 percent per millennium.

The Cretaceous-Tertiary Extinction - the one that creamed the dinosaurs - lasted only 10,000 years. The rate of species loss was 15 percent per millennium.

These extinctions were, of course, exceptional. On average, over the three or four billion years of life's (pre-human) existence, the extinction rate was a mere 0.1 per millennium.

That jumped, from 1900 to 2000, by a factor of 100 to a rate of 10 percent. And in the next 100 years, the rate is expected to reach 20 percent - clearly surpassing even the worst extinctions of the past.

How long do you suppose we ought to allow this to continue?

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