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[Past] Extinction Tied to Global Warming
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| Contributor | ArmyDem |
| Last Edited | ArmyDem Jan 21, 2005 07:17pm |
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| Category | News |
| Media | Newspaper - Washington Post |
| News Date | Friday, January 21, 2005 06:00:00 AM UTC0:0 |
| Description | Greenhouse Effect Cited in Mass Decline 250 Million Years Ago
By Guy Gugliotta
Washington Post Staff Writer
Friday, January 21, 2005; Page A03
Scientists call it "the Great Dying," a 250 million-year-old catastrophe that wiped out 90 percent of ocean species and 70 percent of land species in the biggest mass extinction in Earth's geologic history.
The cause of this cataclysm is a matter of great dispute among paleontologists, but research released yesterday offers new evidence that global warming caused by massive and prolonged volcanic activity may have been the chief culprit.
Huge amounts of carbon dioxide were released into the air from open volcanic fissures known to geologists as the "Siberian Traps," researchers said, triggering a greenhouse effect that warmed the earth and depleted oxygen from the atmosphere, causing environmental deterioration and finally collapse.
A second set of findings suggested that the warming also crippled the oceans' ability to refresh their oxygen supply, causing the seas to go sterile, destroying marine life and allowing anaerobic bacteria (which do not require oxygen) to release poisonous hydrogen sulfide "swamp" gas into the air.
The two reports, prepared independently, both cast doubt on another theory -- that the Great Dying was caused by the impact of an asteroid or comet such as the one that triggered the extinction of the dinosaurs 65 million years ago. |
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