In the last century, certain kinds of animals have gone extinct up to 100 times faster than usual, according to new research.
There have been five documented mass extinctions in the Earth’s history, including when the dinosaurs were suddenly wiped out 65 million years ago. Those extinctions are thought to have been caused by natural disasters, such as massive, earth-darkening volcanic eruptions or cataclysmic asteroid strikes. But a study published Friday concluded that a sixth, human-caused mass extinction is happening now.
We are the problem, according to Gerardo Ceballos, one of the study’s authors and a professor at the Institute of Ecology at the National Autonomous University of Mexico.
“We know that we have been destroying habitat; deforestation is huge,” Ceballos told ThinkProgress. “Thousands of animals are being killed every year for trade, and also by pollution. All these factors, these human factors, are major, and now we have climate change.”
Climate change puts animals at risk in two ways, Ceballos said. One is increased extreme weather, such as a hurricane that hits Puerto Rico and damages the endangered Puerto Rican parrot population. The other is rising temperatures that delicate amphibians can’t adapt to. Both are contributing to the continued loss of biodiversity.
Based on the researchers’ data, published Friday in Advanced Sciences, over the course of the Earth’s existence, it would have taken up to 10,000 years for some of the species that have gone extinct in the last century to disappear.
The analysis is based on a “very conservative” estimate that looks only at vertebrate species and uses a high threshold of documentation for extinction, the study said.
“The results were incredibly, incredibly shocking,” Ceballos said. “To be honest… because we were using such conservative measures, I thought that we wouldn’t be able to find that we were going into a mass extinction.”
Previous studies have been criticized for being overly alarmist, which is why the researchers wanted to look at the issue with new criteria, but the idea of a sixth mass extinction isn’t new. Scientists and ecologists have been arguing for years that a sixth mass extinction is on its way.
According to the IUCN Red List, an international monitoring body, 22 percent of the world’s mammal species are known to be globally threatened or extinct. Since 1500, 76 mammals have disappeared. Nearly a third of the world’s amphibian species are threatened or extinct, and as many as 159 species may already be extinct. At least 38 amphibian species are confirmed to be extinct, while another 120 species have not been spotted in recent years and have possibly died off. (It can take years or even decades to confirm extinction, which is one reason the extinction rate in the study is considered conservative.)
Ceballos said protecting these animals is a moral duty, but it’s also in humanity’s self-interest. For instance, 75 percent of the medicines we currently use are derived from plant and animal compounds, he said.
“Every species we lose, we lose that,” Ceballos said.
The moral argument for environmentalism has gained traction lately, especially with the release of the pope’s encyclical on the environment and climate change. But some have argued that elevating animals over humans is immoral.
At the end of the day, though, we are dependent on the environment for our own existence, Ceballos pointed out.
“There are many reasons we should care about the extinction of species,” he said. “But if we save them, we are saving humans.”