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Mass Extinctions


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#1 bobdrake12

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Posted 24 August 2002 - 07:30 PM


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Big bangs and mega-deaths

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Have you heard about mass extinctions? Probably not...



Have you heard about mass extinctions? Probably not... but because of people doing so much damage to the planet and to the web of life, lots of animals and plants are dying out completely. That's what extinction is. And once a creature is extinct, that's it. There are no second chances. It's gone for ever.

But there's nothing new about mass extinctions. Ninety nine percent of all the different types of life - called species - which have ever lived are now extinct. What is completely new is that this is the first extinction caused by people and their wasteful and polluting ways. All the other extinctions in Earth's long history seem to have been caused by violent natural events.


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The best known of these was the final extinction of the dinosaurs about 66 million years ago.



Less well-known but much worse was a mysterious mega-extinction that happened about 250 million years ago. This was so bad that it destroyed around 96% (96 out of every hundred) of all species of life on the planet.

Understanding mass extinction shows that the global life system is delicate. If it's messed up, it could mean the complete collapse of the life-support systems we all depend upon.


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The important lesson to learn from mass extinctions is that they hit complex life hardest. It's things like bacteria and rats and cockroaches that survive -- not people or (sob!) penguins. You have been warned!

#2 lordprovost

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Posted 21 August 2003 - 04:52 AM

I hate to say it but if you North Americans can't even keep your electricity grid functioning it doesn't bode well for the state or your nuclear industry.


'Ah, Monday morning.Time to pay for your two days of debauchery, you hungover drones.'

- Mr Burns [huh]

#3 kevin

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Posted 27 August 2003 - 09:15 PM

Public release date: 27-Aug-2003
Contact: Megan Fellman
fellman@northwestern.edu
847-491-3115
Northwestern University

Methane thought to be responsible for mass extinction

EVANSTON, Ill. -- What caused the worst mass extinction in Earth's history 251 million years ago? An asteroid or comet colliding with Earth? A greenhouse effect? Volcanic eruptions in Siberia? Or an entirely different culprit? A Northwestern University chemical engineer believes the culprit may be an enormous explosion of methane (natural gas) erupting from the ocean depths.

In an article published in the September issue of Geology, Gregory Ryskin, associate professor of chemical engineering, suggests that huge combustible clouds produced by methane gas trapped in stagnant bodies of water and suddenly released could have killed off the majority of marine life and land animals and plants at the end of the Permian era -- long before dinosaurs lived and died.

The mechanism also might explain other extinctions and climate perturbations (ice ages) and even the Biblical flood, as well as be the cause of future catastrophes.

Ryskin calculated that some 10,000 gigatons of dissolved methane could have accumulated in water near the ocean floor under high pressure. If released quickly, perhaps triggered by an earthquake, the resulting cloud of methane would have an explosive force about 10,000 times greater than the world's entire stockpile of nuclear weapons. The huge conflagrations plus flooding and overturned oceans would cause the extinctions. (Approximately 95 percent of marine species and 70 percent of land species were lost.)

"That amount of energy is absolutely staggering," said Ryskin. "As soon as one accepts this mechanism, it becomes clear that if it happened once it could happen again. I have little doubt there will be another methane-driven eruption -- though not on the same scale as 251 million years ago -- unless humans intervene."


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