Sixth Mass Extinction
Thursday, 30. July 2009, 09:04:36
The classical "Big Five" mass extinctions are End Ordovician, Late Devonian, End Permian, End Triassic, and End Cretaceous (see note below). The Holocene extinction event is referred to as the Sixth Extinction, that is the extinction event that is taking place NOW. This means indeed that the earth's 6th great mass extinction is occurring while you read this post.
A study published in the international journal Conservation Biology is the first comprehensive review of more than 24,000 scientific publications related to conservation in the Oceanic region. Compiled by a team of 14 scientists, it reveals a sorry and worsening picture of habitat destruction and species loss. It also describes the deficiencies of and opportunities for governmental action to lessen this mounting regional and global problem. The review highlights destruction and degradation of ecosystems as the main threat. In Australia, agriculture has altered or destroyed half of all woodland and forests. Around 70% of the remaining forest has been damaged by logging. Loss of habitats is behind 80% of threatened species, the report claims.
According to the IUCN Red List of Threatened Species, 2008
Extinction certainly threatens amphibians [http://www.pnas.org/content/105/suppl.1/11466.abstract] — frogs, salamanders, and caecilians. A detailed worldwide assessment and subsequent updates show that one-third or more of the 6,300 species are threatened with extinction.
• http://www.science.unsw.edu.au/news/extinction-crisis-oceania/
• http://www.guardian.co.uk/environment/2009/jul/28/species-extinction-hotspots-australia
• http://wwf.org.au/news/queensland-land-clearing/
In Danish:
• http://politiken.dk/videnskab/article759526.ece
Note on 5 previous mass extinctions:
A study published in the international journal Conservation Biology is the first comprehensive review of more than 24,000 scientific publications related to conservation in the Oceanic region. Compiled by a team of 14 scientists, it reveals a sorry and worsening picture of habitat destruction and species loss. It also describes the deficiencies of and opportunities for governmental action to lessen this mounting regional and global problem. The review highlights destruction and degradation of ecosystems as the main threat. In Australia, agriculture has altered or destroyed half of all woodland and forests. Around 70% of the remaining forest has been damaged by logging. Loss of habitats is behind 80% of threatened species, the report claims.
According to the IUCN Red List of Threatened Species, 2008
- Nearly 17,000 of the world's 45,000 assessed species are threatened with extinction (38 percent). Of these, 3,246 are in the highest category of threat, Critically Endangered, 4,770 are Endangered and 8,912 are Vulnerable to extinction.
- Nearly 5,500 animal species are known to be threatened with extinction and at least 1,141 of the 5,487 known mammal species are threatened worldwide.
- In 2008, nearly 450 mammals were listed as Endangered, including the Tasmanian Devil (Sarcophilus harrisii), after the global population declined by more than 60 percent in the last 10 years.
- Scientists have catalogued relatively little about the rest of the world's fauna: only 5 percent of fish, 6 percent of reptiles, and 7 percent of amphibians have been evaluated. Of those studied, at least 750 fish species, 290 reptiles, and 150 amphibians are at risk.
- The average extinction rate is now some 1,000 to 10,000 times faster than the rate that prevailed over the past 60 million years.
Extinction certainly threatens amphibians [http://www.pnas.org/content/105/suppl.1/11466.abstract] — frogs, salamanders, and caecilians. A detailed worldwide assessment and subsequent updates show that one-third or more of the 6,300 species are threatened with extinction.
• http://www.science.unsw.edu.au/news/extinction-crisis-oceania/
• http://www.guardian.co.uk/environment/2009/jul/28/species-extinction-hotspots-australia
• http://wwf.org.au/news/queensland-land-clearing/
In Danish:
• http://politiken.dk/videnskab/article759526.ece
Note on 5 previous mass extinctions:
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Cretaceous-Tertiary. 65 million years ago, the dinosaurs were wiped out in a mass extinction that killed nearly a fifth of land vertebrate families, 16% of marine families and nearly half of all marine animals.
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End of Triassic. About 200 million years ago, lava floods erupting from the central Atlantic are thought to have created lethal global warming, killing off more than a fifth of all marine families and half of marine genera.
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Permian-Triassic. The worst mass extinction took place 250 million years ago, killing 95% of all species.
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Late Devonian. About 360 million years ago, a fifth of marine families were wiped out, alongside more than half of all marine genera.
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Ordovician-Silurian. About 440 million years ago, a quarter of all marine families were wiped out.
WIDGETIZE