Sixth Great Extinction Under Way, Scientists Say

pigs
"Mangalica" pigs graze in Kaba, Hungary, May 22, 2015. Mangalicas, which were all but extinct 25 years ago, now feature prominently in some of the best restaurants in the world for their tasty, fatty meat. Laszlo Balogh/Reuters

In addition to the rapidly melting polar ice caps and the widening scarcity of water, our globe's animals are now in the throes of what scientists are calling a "sixth great extinction." In a study published Friday in Science Advances, researchers asserted that the rate of extinction for species in the 20th and early 21st centuries was 100 times higher than it would have been without human interference—another reminder that the greatest threat to the Earth's survival is humankind itself.

The researchers came up with what they call "extremely conservative assumptions" about the current extinction rate and compared it to the average extinction rate throughout history, aiming to draw conclusions as to whether human habits contributed to accelerated extinction in the past century.

The results were grim: The study found that the rate at which vertebrates in particular were dying out has soared eight to 100 times since 1900, with more than 477 vertebrates having become extinct. Natural rates, by contrast, would indicate that only nine species of vertebrates would have become extinct in that time, according to The Guardian.

"This is very depressing because we used the most conservative rates, and even then they are much higher than the normal extinction rate, really indicating we are having a massive loss of the species," said Dr. Gerardo Ceballos, a study co-author and a professor at National Autonomous University of Mexico. "It's really signalling we've entered a sixth extinction and it's driven by man."

What's more, the calculations still probably don't offer a full accounting: "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," researchers wrote in the study.

Scientists have concluded that the surge in extinction rates can be attributed to humans clearing land for farming, the introduction of invasive species and the emergence of carbon emissions and toxins. "There are examples of species all over the world that are essentially the walking dead," said Stanford's Paul Ehrlich in a press release.

While researchers were surprised by the study's results, Ceballos said President Barack Obama's focus on global biodiversity efforts and Pope Francis's recent encyclical on the environment have given him hope. The study's authors say that in order to avoid a true sixth mass extinction, humans will have to embark on "rapid, greatly intensified efforts to conserve already threatened species."