The Earth could be on the brink of the sixth mass extinction in history, claim scientists。
They believe that the steep decline in populations of many animal species, from frogs and fish to tigers, is as fast as any of the last five extinctions in the past 540 million years。
The study, written by scientists from University of California, will be published in the journal Nature。
"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," said Professor Anthony Barnosky。
Nevertheless, Prof Barnosky said it was not too late to save these critically endangered mammals and other such species。
That would require dealing with a perfect storm of threats, including habitat fragmentation, invasive species, disease and global warming。
Biologists estimate that within the past 500 years, at least 80 mammal species have gone extinct out of a starting total of 5,570 species。