On average, “the background extinction rate” will bump off about one species, per million species, per year. But what we’re seeing now is a bit more extreme.
“If we look at the numbers of just mammal extinctions on the continent [Australia] in the last 200 years, they’ve been extraordinary,” said Professor Trish Flemming, a wildlife conservation expert from Murdoch University.
Since Europeans colonized Australia, at least 40 species of terrestrial mammal have gone extinct. That rate is around 600 times faster than the normal background extinction rate, and there are lots of species that we might not even realize have perished.
“We actually have no comprehension of the amount of biodiversity that we have. There’s a whole wealth of things like isopods, spiders and stygofauna, that we never even think about or consider,” said Flemming.
So is this a mass extinction?
Since life began, there have been five occasions where more than three-quarters of all species went extinct within 2.8 million years. These calamities have been used to establish a benchmark for what constitutes a mass extinction: 75% of species gone in 2.8 million years.
Obviously, we haven’t quite run out the clock for this era to officially qualify, but with extinction rates hundreds of times higher than “normal,” it’s hard to view what’s happening as anything else.
“I definitely do think what we’re experiencing is a mass extinction,” said Flemming.
“We keep removing resources and changing and altering habitat in ways that are irreversible…we’re taking resources away that we can’t conceivably replace within our lifetimes.”