Scientists: Mass extinction looms
But others claim tone of report is too alarmist
Have humans damaged the Earth’s ecosystems so severely that we’re well on our way to the biggest mass extinction since the dinosaurs vanished 66 million years ago? And are we running out of time to reverse the negative impacts of our actions?
Three scientists who have studied extinctions of thousands of species of vertebrates believe so, although others are skeptical of the doomsday-like findings.
A study published this month paints a grim picture: The populations of nearly 9,000 vertebrate species, including mammals such as cheetahs, lions and giraffes, have significantly declined between 1900 and 2015. Almost 200 species have gone extinct in the past 100 years. The study says the losses are indicative of the planet’s “ongoing six major extinction events” and has cascading consequences for human life on Earth.
“This is the case of a biological annihilation occurring globally, even if the species these populations belong to are still present somewhere on Earth,” Rodolfo Dirzo, the study’s co-author and a Stanford University biology professor, said in a news release.
The researchers analyzed 27,600 species of birds, amphibians, mammals and reptiles — about half of all known vertebrate species — and found that 8,851 (about 32 percent) have seen declining populations and shrinking areas of habitat. A more detailed analysis of 177 mammal species found that more than 40 percent have experienced significant drops in population. The findings, the study says, mean that billions of animal populations that once roamed the Earth are now gone.
The authors describe the shrinking population of species as “a massive erosion of the greatest biological diversity in the history of Earth.”
“Thus, we emphasize that the sixth mass extinction is already here and the window for effective action is very short, probably two or three decades at most,” the authors wrote. “All signs point to ever more powerful assaults on biodiversity in the next two decades, painting a dismal picture of the future of life, including human life.”
A few examples: There were only a little more than 7,000 cheetahs in existence last year, and their population may drop another 53 percent in the next 15 years, according to National Geographic. Borneo and Sumatran orangutans have been considered endangered for years mainly because of loss of habitat.
The population of African lions has dropped by more than 40 percent in the past 20 years. West African lions, in particular, are nearing extinction, with only about 400 animals left. Historically, lions roamed southern Europe, the Middle East, northwestern India and most of Africa. Today, there are only scattered populations in sub-Saharan Africa and a few remnants at Gir Forest National Park in India, according to the study.
The driving force is a steady drumbeat of human activities that result in habitat losses, pollution and climate disruption, among others.
“The massive loss of populations and species reflects our lack of empathy to all the wild species that have been our companions since our origins,” the study’s lead author, Gerardo Ceballos, an ecology professor at the Universidad Nacional Autónoma de México, said in the news release.
Some in the scientific community disagree with the study’s grim findings. Stuart Pimm, head of the conservation ecology at Duke University, said the study unnecessarily raises alarms. Pimm believes the sixth mass extinction is just beginning, not well on its way.
“It’s a little bit dramatic,” Pimm said. “Yes, we are driving species to extinction a thousand times faster than we should. So yes, there is a problem. But on the other hand, telling people that we’re all doomed and going to die isn’t terribly helpful.”