Thursday, July 26, 2007

The End is Near (okay 12 million years away)

With a tongue firming in the cheek, but based on some peer-reviewed science, the Scientific American blog reports that we will suffer a life-ending extinction event in 12 million years:

I know there are disasters just over the horizon--terrorism, climate change, the rapture--but some ends to the human race are so profoundly unavoidable that they deserve further scrutiny, even if it's just to satisfy my need for some kind of secular eschatology.

Back in May, a pair of researchers at the University of Kansas proposed a unique solution to the puzzling periodicity of mass extinctions on Earth--which happen about once every 62 million years.

According to Adrian Melott, professor of physics and astronomy at KU, the motion of the solar system exposes Earth to an onslaught of cosmic rays on a schedule that is synchronized to the mass extinctions.

That white dot is us, oscillating through the periphery of our parent galaxy along that helpfully-illustrated snaky green path. Of doom.

Like Baltimore, St. Louis or (insert economically depressed city here) writ large, the galaxy has a good side of town and a bad side. Keep this in mind the next time you're piloting a faster-than-light spaceship home after a few too many: The bad side of the Milky Way is the north side.

The KU researchers hypothesize that the leading, north side of the Milky Way generates a shock wave as the galaxy plunges through the universe.

When the solar system periodically journeys up to the north boundary of the galaxy -- about once every 64 million years -- the galactic shock wave exposes Earth to a huge dose of high-energy radiation.

In other words, the earth is periodically irradiated like a steaming heap of potentially contaminated ground chuck, only it ain't just the salmonella that are wiped out.

The one thing that was left out of much of the original reporting on the story, the Letters section of the July 14 issue of Science News informs me, is when we're due for another trip to the wrong side of the tracks:

"We've just passed the mid-plane of the galaxy," said Melott. "We're on the way up and we'll reach a peak in about 10 or 12 million years. That's when the radiation should start getting bad again -- if our idea is right."

"As for the next die-off, there is plenty of time to prepare," cheerfully notes the pr department of the University of Kansas.

Read the post here.

The KU press release ofers a bit more details--and even offers a silver lining:

Melott said a bath of cosmic rays produced by the Milky Way’s shock wave could cut down numbers of Earth’s species in a variety of ways: boosting exposure to elementary particles called muons, creating a blanket of planet-cooling clouds and damaging the ozone layer so that increased radiation causes more mutations, cancers and cataracts.

According to Melott, radiation weakens the biosphere for prolonged periods so that when sudden events occur, such as meteor hits or volcanic eruptions, the disturbance to life on Earth is more severe. “It’s like having the flu and then getting shot,” Melott said.

But the news is not all bad for Earth’s inhabitants. Data shows that while overall diversity of Earth’s species drops during the 62-million-year cycle, it also rebounds every time, like a spring.

“Radiation could increase the number of mutations and also help new species arise,” said Melott. “During these times of lowered biodiversity a lot of new species come into existence, which ride the wave up to the new peak of biodiversity.”

Read the KU press release about the bad news here

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