BERKELEY, Calif., March 2 (UPI) -- With many of Earth's animal species declining, some scientists are warning of mass extinctions, something that has occurred five times in 540 million years.
Each of the previous mass extinctions resulted in at least three-quarters of all animal species going extinct.
University of California, Berkeley, paleobiologists studying the status of mammals and other species in terms of possible extinction, compared to past episodes, say they find cause for hope as well as alarm, a UCB release reported Wednesday.
"If you look only at the critically endangered mammals … and assume that their time will run out, and they will be extinct in 1,000 years, that puts us clearly outside any range of normal, and tells us that we are moving into the mass extinction realm," said Anthony D. Barnosky, UCB professor of biology. "If currently threatened species -- those officially classed as critically endangered, endangered and vulnerable -- actually went extinct, and that rate of extinction continued, the sixth mass extinction could arrive within as little as 3 to 22 centuries."
However, he said, it's not too late to save critically endangered mammals and other such species and stop short of the tipping point.
"So far, only 1 (percent) to 2 percent of all species have gone extinct in the groups we can look at clearly, so by those numbers, it looks like we are not far down the road to extinction," Barnosky said. "We still have a lot of Earth's biota to save."
That would mean dealing with habitat fragmentation, invasive species, disease and global warming, he said.
"It's very important to devote resources and legislation toward species conservation if we don't want to be the species whose activity caused a mass extinction," Barnosky said.