Global Species Survival “In Crisis,” Red List Says

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 bblock@worldwatch.org.