New Recipe: How To Make A Mass Extinction

[RestoreGore]

Mr. Gore is so right about the "planetary emergency" we now face, and that is why this requires a higher calling on all our parts to see it and act. This is so beyond any political rhetoric.
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http://news.yahoo.com/s/space/20061027/sc_space/newreci...

Michael Schirber
Special to LiveScience
LiveScience.com
Fri Oct 27, 1:30 PM ET

Apocalypses may not be all fire and brimstone. A growing number of paleontologists say that Earth-smashing meteors cannot take all the blame for the many mass extinctions that dot our planet's fossil record. The true causes seem to be more complex. "The impact model has been so successful because it's easy to explain and easy to understand," said Nan Arens of Hobart and William Smith College in Geneva, NY. "However, the simple answer isn't always the best one."

At the annual meeting of the Geological Society of America this week in Philadelphia, Arens and others argued that the combined punch of volcanoes, climate change and impacts leaves many species teetering on the brink of extinction. One final blow brings collapse.

The same scenario could be happening now.

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Common diagnosis

A sick Earth succumbing to a final shock is apparently a common extinction formula. Arens and her colleagues analyzed geologic data from the last 488 million years and found more species died out when the environment was first stressed and then stung. Specifically, the researchers compared stress-inducing volcanic activity and catastrophic meteor impacts. Only when the Earth experienced both did extinction rates significantly increase.

"Periods of stress are going to reduce population sizes," Arens said. With reduced numbers, "species are vulnerable to pulse catastrophes."
On the flip side, an unstressed environment is resilient to geologic and climatic disasters because life is diverse and geographically spread out.

And now?

Applying their model to the present, Arens and her collaborators speculate that human activity has both stressed the environment with agriculture and shocked it with fossil fuel burning. Whether or not this is an accurate description, both Bottjer and Keller agree that we are in a precarious situation.

"Under conditions any disaster that might strike (impact or volcanism or major greenhouse warming), which ordinarily would not cause major extinctions, will put much of Earth's biota at risk of extinction," Keller said.

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Original Story: New Recipe: How to Make a Mass Extinction

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[Warpy]

1. New research is indicating the dinosaurs went out

with more of a whimper than a bang. Climate change had been causing a dieoff for a few centuries when the asteroid and tsunami finished them off. Scientists had long wondered why there wasn't a mass of dinosaur bones right at the iridium layer. The slow dieoff is why.

That asteroid probably did them a favor. Life must have been miserable for them toward the end.

The question is whether or not we'll be able to cope with the changes in climate. There will certainly be a lot fewer of us in a few hundred years, and that's a good thing. Getting to a lower, sustainable population will be miserable.

Gore still thinks it's preventable. I no longer think so.