Researchers say there’s a ‘biological annihilation occurring globally’
Biologists say more than 30 percent of all vertebrates have declining populations in what they call a ‘biological annihilation’ that is occurring globally.
A 2015 study 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, according to a Stanford University press release.
“We are now in the middle of the sixth great mass extincion to occur on Earth. We’re losing species at an extraordinarely rate compared to the background rate in which we lost them between the prevous five great extinctions. Couple of species a year disappearing a year turns out to be ten to a hundred time as fast as it happened in the past,” Paul Ehrlich, professor emeritus of biology said.
In a new analysis, recently published in Proceedings of the National Academy of Sciences, scientists mapped the ranges of 27,600 species of birds, amphibians, mammals and reptiles – a sample representing nearly half of known terrestrial vertebrate species – and analyzed population losses in a sample of 177 well-studied mammal species between 1990 and 2015.
The study, led by Gerardo Ceballos of the National Autonomous University of Mexico, finds more than 30 percent of vertebrate species are declining in population size and range. Of the 177 mammals for which the researchers had detailed data, all have lost 30 percent or more of their geographic ranges and more than 40 percent have lost more than 80 percent of their ranges. Tropical regions have had the greatest number of decreasing species while temperate regions have seen similar or higher proportions of decreasing species. Particularly hard hit have been the mammals of south and southeast Asia, where all the large-bodied species of mammals analyzed have lost more than 80 percent of their geographic ranges.
The study’s maps suggest that as much as 50 percent of the number of animal individuals that once shared Earth have disappeared, as have billions of animal populations. This amounts to “a massive erosion of the greatest biological diversity in the history of Earth,” the authors wrote in their research.
The loss of populations and biological diversity matters because, apart from leading to a species extinction, it robs humans of crucial ecosystem services such as honeybees’ crop pollination, pest control and wetlands’ water purification.