From rhinos to tigers to elephants, three out of four “familiar” animal species – those commonly thought of and well understood by human beings – will be extinguished within three human lifetimes, a new study finds, confirming that Earth is in the midst of what’s become known as the “sixth mass extinction” driven by runaway development, shrinking animal habitats and climate change.
“Scientists never like to say anything for sure, but this is close as we’re ever going to get to saying, ‘We’re certain that this is a huge problem,’” says study coauthor Anthony Barnosky, a paleontologist at the University of California-Berkeley, calling the problem “quite dire.”
The hundreds of species eliminated in the past century alone would otherwise have lasted at least another 800 to 10,000 years, the study found. Coral reefs “are in danger of annihilation” as soon as 2070, Barnosky says, potentially erasing a quarter of the ocean’s species.
The last mass extinction occurred 66 million years ago with the end of the dinosaurs. This is the only one, however, where a single species is responsible for the destruction of all the others. And by eliminating biodiversity, it threatens to disrupt the pollination, water purification, food chain and other “ecosystem services” that humanity’s “beautiful, fascinating and culturally important living companions” provide, the study says – threatening human life itself.
“You can kind of think of it as guns and bullets,” Barnosky says. “The guns are different in each case, but the bullets that come out – changing climate, increased CO2 and other gases in the atmosphere, ocean acidification – those things that contribute to mass extinction are the things that we’re doing today.”
Previous studies had established the world is in the midst of a mass extinction, with animals disappearing at far faster rates than expected. The term even made the title of New Yorker writer Elizabeth Kolbert’s 2014 bestseller, “The Sixth Extinction.” There is no way to know just how many species there are on earth – roughly 1.3 million animals have been described since 1758. A study last September, however, found the number of wild animals had likely been halved in just the past 40 years.
But this latest effort is by far the most conservative: a study aimed at debunking any possible rebuttal that its findings are “alarmist.”
Barnosky and his team, hailing from Florida and Mexico as well as California, doubled the pace that species were expected to go extinct without any human interference, then used the lowest possible estimate for the number of species that actually were disappearing.
The results, even as an underestimate, proved just as dire.
Since 1900, birds, mammals, reptiles, amphibians and fish died 72 times faster than “normal,” this most conservative estimate found. Whereas researchers might have expected nine veterbrates to go extinct, instead 468 were wiped from the Earth.
Industrialization was especially lethal, with extermination rapidly accelerating from 1800 on.
“The most iconic bird species historically are gone – the ivory-billed woodpecker, passenger pigeon, Carolina parakeet, great auk, imperial woodpecker,” says study coauthor Paul Ehrlich, professor and president of the Center for Conservation Biology at Stanford University. “But there are many others less-well known – the gorgeous orange-bellied and golden-shouldered parrots of Australia, many large raptors, and likely many penguins – as climate disruption takes hold.”
The study was released one day after Pope Francis issued the Vatican’s first-ever encyclical on the environment and climate change, a 184-page letter urging Catholics and “all humanity” to respect nature, rein-in development and address global warming. It also comes six months ahead of a U.N. climate summit in Paris, where President Barack Obama and other world leaders reportedly hope nearly 200 nations will agree to reduce their carbon emissions.
Francis emphasized the need for swift action, a theme echoed by the research team.
“It really is possible to fix these big problems if people put their minds to it,” Barnosky says. “We’re at a stage now where people are becoming aware of the problem, and as people become aware we can move the needle toward making progress.”
That includes switching from fossil fuels to
sources like wind and solar, producing food more efficiently and limiting population growth. But no matter what actions are taken, there will inevitably be a cost, experts say.“We’re not only in the midst of a sixth major extinction, we’re moving further and further into it,” says Bruce Stein, senior director of climate adaptation and resilience at the National Wildlife Foundation. “It’s clear that we are going to lose a lot of things, but it’s also clear that we have the ability to ensure that many of our systems will be different but will continue to have ecological functionality and continue to support many of these species.”