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One World.net's take: Over a third of the world's species are threatened with extinction according to the latest findings from a major biodiversity conservation organization.

• A young tiger in the zoo of Zürich, Switzerland. © Tambako the Jaguar (flickr)The International Union for Conservation of Nature (IUCN) publishes an annual Red List of Threatened Species that is widely recognized as a comprehensive inventory of the world's plant and animal life. IUCN researchers use a set of criteria to place species into one of nine categories, of which the most urgent are Critically Endangered, Endangered, and Vulnerable. The classification criteria for these three groups include factors such as rate of decline, population size, area of geographic distribution, and many others.

• The tiger is one of the mammals listed as endangered on the IUCN Red List. Relatively large areas are required for a tiger population to thrive, and many protected areas are too small to conserve tigers. Habitat destruction, climate change, poaching, and disease have negatively impacted the tiger and many other species around the world.

Global Species Survival "In Crisis," Red List Says

From: Worldwatch Institute

by Ben Block
October 7, 2008

More than a third of the world's species are threatened with extinction, according to the latest international biodiversity assessment from the World Conservation Union (IUCN).

The IUCN's Red List of Threatened Species, considered the authority on the status of the world's species, was updated this year to include 44,838 species. Of these, about 38 percent are designated as "threatened" and 7 percent are "critically endangered."

Continued habitat depletion, deadly diseases, and climate change are all posing dire threats to biodiversity across the world, conservationists warned at the IUCN's World Congress in Barcelona.

"Within our lifetime, hundreds of species could be lost as a result of our own actions," said Julia Marton-Lefevre, the IUCN Director-General.

The updated assessment includes the most comprehensive review of the world's mammals ever completed. The study, which will be published in the journal Science this week, counted 1,141 of the world's 5,487 mammals, about one-fourth, as threatened.

The list added 366 species of amphibians, bringing the total of threatened or extinct amphibians to 1,983, or 32 percent. Holdridge's Toad, native to the rainforests of Costa Rica, was officially declared extinct after not having been seen since 1986.

The status of mammals, amphibians, and other classes may be even more severe; however, a lack of sufficient data prevents a more accurate assessment. The IUCN said it does not have enough information about 836 mammals to declare their status and that the share of threatened mammals could be as high as 36 percent, said Jan Schipper, program coordinator for the IUCN and Conservation International's joint global mammal assessment and the lead author of the Science study.

"We have social, political, and economic indexes. But we lack broad biodiversity indexes," Schipper said. "This is vital for our global species' existence."

Ben Block is a staff writer with the Worldwatch Institute. He can be reached at .

For more information about species conservation, visit the Worldwatch Institute.