How they "think"-----Earth is on its way to the biggest mass extinction since the dinosaurs, scientists warn - The Washington Post

Earth is on its way to the biggest mass extinction since the dinosaurs, scientists warn - The Washington Post:
"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, though others are skeptical of the doomsday-like findings.
A new study published Monday 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 alone — a rate of two per year.
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.
...“I am an alarmist. My colleagues are alarmists. We're alarmed, and we're frightened.
And there's no other way to put it,” he said..."