From: Stanford University
Published July 11, 2017 09:20 AM

Prelude to global extinction: Stanford biologists say disappearance of species tells only part of the story of human impact on Earth's animals

No bells tolled when the last Catarina pupfish on Earth died. Newspapers didn’t carry the story when the Christmas Island pipistrelle vanished forever.

Two vertebrate species go extinct every year on average, but few people notice, perhaps because the rate seems relatively slow – not a clear and present threat to the natural systems we depend on. This view overlooks trends of extreme decline in animal populations, which tell a more dire story with cascading consequences, according to a new study that provides the first global evaluation of these population trends.

“This is the case of a biological annihilation occurring globally, even if the species these populations belong to are still present somewhere on Earth,” said co-author Rodolfo Dirzo, a professor of biology.

Mapping loss

A 2015 study co-authored by Paul Ehrlich, professor emeritus of biology, and colleagues showed that Earth has entered an era of mass extinction unparalleled since the dinosaurs died out 66 million years ago. The specter of extinction hangs over about 41 percent of all amphibian species and 26 percent of all mammals, according to the International Union for Conservation of Nature (IUCN), which maintains a list of threatened and extinct species. This global disaster scene has the fingerprints of habitat loss, overexploitation, invasive organisms, pollution, toxification and climate change.

Read more at Stanford University

Image: Tropical forest logging has contributed to population declines in many animals, including the Bornean gibbon, known for its whooping call. (Credit: Gerardo Ceballos)

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