Sixth mass extinction ‘already triggered’

Humans have already triggered the start of Earth’s sixth mass extinction, thereby threatening their own future as a species, a study has claimed.

The window of opportunity to prevent the worst diversity disaster since dinosaurs were swept from the planet 65m years ago is “rapidly closing”.

In the last century, vertebrates have been disappearing at a rate 114 times higher than would normally be expected without the destructive influence of humans, according to the scientists, who insist their analysis is “extremely conservative”.

If the pace of extinction is allowed to continue, species loss will have a significant effect on human populations in as little as three generations, it is claimed.

Once the damage is done, it could take millions of years for nature to recover, said the researchers.

They pointed out that, since 1900, more than 400 more vertebrates than expected had vanished. The lost animals included 69 mammal, 80 bird, 24 reptile, 146 amphibian, and 158 fish species.

Today, the spectre of extinction hangs over 26% of all mammalian species and 41% of all amphibians.

Paul Ehrlich, from Stanford University in California, a leading member of the team, said: “Without any significant doubt... we are now entering the sixth great mass extinction event. There are examples of species all over the world that are essentially the walking dead. We are sawing off the limb that we are sitting on.”

Loss of species disrupts ecosystems, leading to serious knock-on effects that are experienced by humans, the scientists stressed. Crop pollination by bees and the water purification of wetlands were two examples of biodiversity benefits which could be lost in three human lifetimes.

Mexican lead researcher Gerardo Ceballos, of the Universidad Autonoma de Mexico, warned that humans could one day follow in the footsteps of the dinosaurs.

“If it is allowed to continue, life would take many millions of years to recover, and our species itself would likely disappear early on,” said Dr Ceballos.

Mass extinctions have occurred on five occasions throughout the history of life on Earth. The last event happened 65m years ago when a giant meteor smashed into the planet, altered the climate, and wiped out the dinosaurs.