There have been five mass extinction events on planet Earth over the past 540 million years. Among these are the asteroid strike that is thought to have killed off the dinosaurs roughly 65 million years ago, and four less infamous extinctions, such as the “Permian event” that occurred 250 million years ago.
During these periods, at least three-quarters of all species on earth went extinct. The dinosaurs vanished, as did the giant insects of the Permian era.
Biologists now suggest that a sixth extinction is underway.
“We see a very consistent move toward decline in species richness, in populations, which results eventually in species extinctions,” said Johannes Foufopoulos, an associate professor at the School of Natural Resources and Environment at the University of Michigan.
Unlike prior periods, it isn’t asteroids or geological shifts causing the rapid disappearance of fauna and flora. Rather, according to Foufopoulos, it’s us – human beings. Climate change, habitat destruction, and overharvesting are among the ways homo sapiens are wreaking havoc on other species.
“If you look at this pattern of human activities you see this exponential increase in impact,” he said. “And matching that is the number of extinctions. So what we’re seeing is species going extinct as an accelerated rate.”
Foufopoulos said that here in Michigan, species in the southern third of the state have been severely affected by habitat loss. While ecosystems in northern Michigan are in better shape, forest practices in the Upper Peninsula remain an issue.
The passenger pigeon is a particularly stark example of a recent manmade extinction. Once the most common bird in North America, it was not unusual for flocks consisting of millions of birds to darken the skies over the region stretching from the Great Plains to the Atlantic littoral. But hunting and deforestation eventually led to the demise of the bird, which was gone from the earth by the 1920s.
Not all modern extinctions receive as much notoriety as the passenger pigeon. In fact, most don’t receive any notice at all. According to Foufopoulos, it’s likely that thousands of species now go extinct each year, most of them unknown to biologists.
Nonetheless, Foufopoulos argues that such shifts in the biosphere could have a major impact on human life. He pointed to recent declines in bee populations as an example of how society relies on healthy ecosystems in ways we don’t always understand.
“We depend for proper ecological function and for appropriate ecosystem services to species we may not be aware of,” he said.
Listen to our full interview with Johannes Foufopoulos above.