Species extinction can herald ecosystem collapse

One million species are threatened with extinction. Now scientists who have studied the largest mass extinction in the history of the earth are warning that species extinction can “tip over” in a collapse of the ecosystems.

If development continues at today’s pace, one million species risk extinction within the next few decades, according to the UN’s expert panel on biological diversity. Many scientists believe we are approaching a sixth mass extinction.

Of the previous five mass extinctions that took place, the largest occurred at the end of the Permian period, 252 million years ago. It was likely triggered by massive volcanic eruptions that led to extreme global warming.

To better understand this event – when 95 percent of all species were wiped out – the researchers in the new study analyzed marine fossils from southern China, which at the time was a shallow sea, from the time before, during and after the mass extinction. In this way, they were able to recreate a kind of model of the ecosystem of that time.

Two phases

The results, which are published in the scientific journal Current Biology, indicate that a crisis for biodiversity can be a harbinger of a more extensive ecosystem collapse, the researchers write.

The mass extinction took place in two phases. In the first, half of the Earth’s species disappeared but the ecosystem remained relatively stable, according to the study. There were still species similar to those that became extinct and that could fill their “niche”, their ecological function.

But during the second phase, around 60,000 years later, the last species capable of filling each niche began to die out – with severe effects on ecosystems as a result.

Reverse the trend

“Ecosystems were pushed to a tipping point from which they could not recover,” said Yuangeng Huang of the China University of Geosciences, one of the researchers behind the study, in a press release.

Today, the loss of species is faster than during previous mass extinctions, according to the researchers, and they argue that their study underscores the importance of reversing the human-caused trend.

“It is likely that we are in the first phase of another, more serious mass extinction. We cannot predict the tipping point that will lead to a total collapse of ecosystems. But it is an inevitable outcome if we do not reverse the loss of biodiversity,” says Yuangeng Huang.

Facts

Mass extinctions

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