Human-driven biodiversity loss faster than mass extinction when dinosaurs were wiped out, study finds

The damage humans are doing to the world is now so great that in some ecosystems the biodiversity loss exceeds the rate of extinction at the time the dinosaurs died out, and the destruction could require millions of years to undo, scientists have said.

A new study shows that the current rate of biodiversity decline in freshwater ecosystems, which are among the world’s most threatened, is up to three times higher than the period during which the dinosaurs went extinct, and over the next century a third of all living freshwater species may have vanished.

This high level of biodiversity collapse is “unprecedented” even within previous mass extinctions, the team from Justus Liebig University in Germany said.

The current biodiversity crisis, now widely referred to as the 6th mass extinction, is one of the critical challenges we face in the 21st century, alongside – and closely related to – the climate crisis.

Numerous species are threatened with extinction, mostly as a direct or indirect consequence of human activity.

Key causes of biodiversity decline include large-scale habitat destruction, the climate crisis, overexploitation of land and animals, pollution and proliferation of invasive species.

“Losing species entails changes in species communities and, in the long run, this affects entire ecosystems,” said Dr Thomas Neubauer, of the university’s Department of Animal Ecology & Systematics, who led the research.

“We rely on functioning freshwater environments to sustain human health, nutrition and fresh water supply.”

The scientists said that during the world’s 5th mass extinction event – the result of a large asteroid impact in Mexico 66 million years ago, when the dinosaurs died out – eradicated about 76 per cent of all species on the planet.

But despite the impact being a single, rapid event, the effects were extremely long-lasting.

The extinction rate remained high for approximately five million years. Afterwards there followed an even longer period of recovery. In total it took almost 12 million years until the balance between species originating and going extinct was restored.

To make the comparison, the research team gathered a large dataset containing 3,387 fossil and living snail species of Europe covering the past 200 million years.

The scientists estimated rates of speciation and extinction to assess the speed at which species come and go and predict recovery times.

They described the results as “alarming”.

“While already the extinction rate during the 5th mass extinction was considerably higher than previously believed for freshwater biota, it is drastically overshadowed by the predicted future extinction rate of the current 6th mass extinction event,” they said.

“Even if our impact on the world’s biota stops today, the extinction rate will likely stay high for an extended period of time,” said Dr Neubauer.

“Considering that the current biodiversity crisis advances much faster than the mass extinction event 66 million years ago, the recovery period may be even longer.

“Despite our short existence on Earth, we have assured that the effects of our actions will outlast us by millions of years.”

The research is published in the journal Communications Earth & Environment.