PROVIDENCE, R.I. [Brown University] — It’s hard to comprehend how bad the current rate of species extinction around the world has become without knowing what it was before people came along. The newest estimate is that the pre-human rate was 10 times lower than scientists had thought, which means that the current level is 10 times worse.
Extinctions are about 1,000 times more frequent now than in the 60 million years before people came along. The explanation from lead author Jurriaan de Vos, a Brown University postdoctoral researcher, senior author Stuart Pimm, a Duke University professor, and their team appears online in the journal Conservation Biology.
“This reinforces the urgency to conserve what is left and to try to reduce our impacts,” said de Vos, who began the work while at the University of Zurich. “It was very, very different before humans entered the scene.”
In absolute, albeit rough, terms the paper calculates a “normal background rate” of extinction of 0.1 extinctions per million species per year. That revises the figure of 1 extinction per million species per year that Pimm estimated in prior work in the 1990s. By contrast, the current extinction rate is more on the order of 100 extinctions per million species per year.
Orders of magnitude, rather than precise numbers are about the best any method can do for a global extinction rate, de Vos said. “That’s just being honest about the uncertainty there is in these type of analyses.”