The researchers analysed more than 70,000 species for the study.
A new study has revealed that almost half of the planet's species are experiencing rapid decline in population. It also said that the loss of global wildlife is "significantly more alarming", blaming humans for the "sixth mass extinction" that is drawing closer. The study has been published in the journal Biological Reviews. This comes months after another study revealed new details about the first mass extinction on Earth that took place 550 million years ago during a period known as the Ediacaran.
In the latest study, the researchers said that humans have already wiped out huge numbers of species and pushed many more to the brink. It added that the next mass extinction event will also happen because of humans.
The researchers analysed more than 70,000 species on the planet, including mammals, birds, reptiles, amphibians, fish and insects to arrive at this conclusion.
"Other studies, based on considerably smaller numbers of species, have shown that the ongoing 'extinction crisis' is more severe than generally appreciated. Our findings provide a stark confirmation on a global scale," Co-author Daniel Pincheira-Donoso, from the School of Biological Sciences at Queen's University Belfast told CNN.
The researcher added that the study provides a "clearer picture" about the extent of the global erosion of biodiversity.
The threat to species is gauged by the labels International Union for Conservation of Nature (IUCN), a United Nations committee, gives to them. So far, the IUCN list classifies about 28 per cent of species as under threat of extinction.
But the new research says 33 per cent of the species currently classed as "non-threatened" on the IUCN Red List are in fact declining towards extinction.
"What our study shows is not whether species are currently classed as threatened or not, but instead, whether their population sizes are becoming rapidly and progressively smaller or not," Mr Pincheira-Donoso said.
While mammals, birds and insects are seeing a decline in numbers, amphibians are particularly badly affected overall, said the study. Apart from disease and impacts of climate change, these species are facing many other threats.
The population of fish and retiles appear to be stable, rather than declining, it further said.