Today, the rate is at least 1,000 times greater than the 0.1 figure at 100 extinctions per year per million species, but could be up to 1000 per 1 million, Dr Pimm said.
Although a combination of numerous factors is responsible for the acceleration in disappearance of species, the biggest is habitat loss caused by humans, Dr Pimm and co-author Clinton Jenkins from the Institute of Ecological Research in Brazil said.
Other major issues are invasive species introduced by humans crowding out native species, climate change affecting where species can survive and overfishing.
A good example is the buffy-tufted-ear marmoset Dr Jenkins said development in Brazil has decimated its habitat while a competing marmoset has taken over where it lives.
The oceanic white-tip shark used to be one of the most abundant predators on Earth, but they have been hunted so much they are now rarely seen, added Dalhousie University marine biologist Boris Worm, who praised the study. "If we don't do anything, this will go the way of the dinosaurs."
Other species at great risk include the Sumatran rhinoceros, Amur leopard and mountain gorilla.
Dr Pimm and Mr Jenkins did however say there is some hope. Both said the use of smartphones and applications such as iNaturalist will help ordinary people and biologists find species in trouble, they said. Once biologists know where endangered species are, they can try to save habitats and use captive breeding and other techniques to save the species, they said.
One success story is the golden lion tamarin. Decades ago the tiny primates were thought to be extinct because of habitat loss, but they were then found in remote parts of Brazil and bred in captivity, and biologists helped set aside new forests for them to live in, Dr Jenkins said.
"Now there are more tamarins than there are places to put them," he said.
- Independent, additional reporting by AP
