The sixth mass extinction in Earth's history is already underway and is more severe than previously thought, say scientists who warn that human overpopulation and overconsumption has led to the massive loss of wildlife.
Scientists found billions of regional or local populations have been lost.
The study, published in the journal Proceedings of the National Academy of Sciences, calls the loss of wildlife a "biological annihilation" that represents a "frightening assault on the foundations of human civilisation".
Previous studies have shown species are going extinct at a significantly faster rate than for millions of years before, but even so extinctions remain relatively rare giving the impression of a gradual loss of biodiversity.
The new work instead takes a broader view, assessing many common species which are losing populations all over the world as their ranges shrink, but remain present elsewhere.
The scientists found that a third of the thousands of species losing populations are not currently considered endangered and that up to 50 per cent of all individual animals have been lost in recent decades.
Almost half of land mammals have lost 80 per cent of their range in the last century, 'The Guardian' reported.
The scientists found billions of populations of mammals, birds, reptiles and amphibians have been lost all over the planet, leading them to say a sixth mass extinction has already progressed further than was thought.
"The resulting biological annihilation obviously will have serious ecological, economic and social consequences," researchers said.
"Humanity will eventually pay a very high price for the decimation of the only assemblage of life that we know of in the universe," they said.
The research analysed data on 27,500 species of land vertebrates and found the ranges of a third have shrunk in recent decades.
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