Earth has entered into a sixth period of mass extinction with levels of species going extinct unparalleled since the dinosaurs died out 66 million years ago, a new study has found.
“[The study] shows without any significant doubt that we are now entering the sixth great mass extinction event,” study co-author Paul Ehrlich Bing, Professor of Population Studies in Biology and a senior fellow at the Stanford Woods Institute for the environment, announced in a Stanford University press release.
Vertebrate species are going extinct 114 faster than they would if there were no humans around, according to the authors of the study, which was published in the Science Advances journal.
“Our activities are causing massive loss of species that has no precedent in the history of humanity and few precedents in the history of life on Earth,” said lead researcher Gerardo Ceballos, a professor of conservation ecology at the Universidad Autónoma de México.
Researchers used data from a 2011 study in the Journal Nature to calculate the current background extinction rate, which is the average rate of species dying out between mass extinctions. According to the data, the earth has lost two species of vertebrae out of 100,000 species every 100 years, which is double the number other studies have found.
They compared this background rate with data from the International Union for Conservation of Nature (IUCN) Red List of 2014, which lists species which have gone extinct and possibly extinct since 1500.
Just nine vertebrate species should have gone extinct since 1900, if it was in line with natural background rate, the study found. But, during the same period, 468 vertebrate species have gone extinct, including 69 mammalian species, 80 bird species, 146 amphibians, and 158 fish.
"We emphasize that our calculations very likely underestimate the severity of the extinction crisis, because our aim was to place a realistic lower bound on humanity's impact on biodiversity," the researchers wrote in the paper.
When a species disappears, its role in the complex ecosystem also vanishes. If the bee, for example, “disappeared off the face of the earth, man would only have four years to live,” since there would be no pollination of crops.
Human made carbon emissions causing climate change, land clearing for farming, and toxins such as pesticides are some but not all of the activities destroying species’ natural habitats.
“There are examples of species all over the world that are essentially the walking dead,”
"We are sawing off the limb that we are sitting on.” Ehrlich said.