I’ve read about elephant poaching and the illegal ivory trade. I’m aware of shrinking forests worldwide and how rising temperatures threaten to magnify deadly insect-borne diseases. Yet I don’t always connect the dots between these particular crises and our swelling human population and the demands we make on various ecosystems.
After spending an hour inside the fourth floor office of biologist Rodolfo Dirzo on the sprawling Stanford University campus last week, however, the links between the stressors we are putting on ecosystems and species and the stressors we are placing on our own species became clear.
Dirzo, who is also a senior fellow at the Stanford Woods Institute for the Environment, coined the term “Anthropocene defaunation” to describe biodiversity loss caused by human activity.
Consider these numbers from a paper Dirzo published in the journal Science this past July: 322 species of vertebrates on land have died off since 1500. The abundance of the remaining creatures has fallen 25 percent on average.
In the last 500 million years, the planet has gone through five major extinction events, the most famous being the die-off of dinosaurs when meteors crashed into the Yucatan Peninsula. Now many scientists concur that we are entering the sixth major extinction, driven by one species: that’s us, Homo sapiens.
“We calculated that the rate of extinction is hundreds or thousands times more intense than it used to be. It’s very intense,” said Dirzo.
Dirzo, who earned his Ph.D. in ecology at the University of Wales, spent his childhood in Mexico, climbing trees, collecting insects, and checking out plants and animals in the wilderness. He has continued that exploration, albeit in a more disciplined fashion, throughout his career.
Read the rest of my conversation and video clips with Dirzo at Climate Confidential on Beacon.