Earth is embarking on its sixth greatest extinction event in its 3.5 billion year history.

That is the finding of a major study conducted by a number of universities including Princeton, Stanford, Berkeley and the University of Mexico which paints a rather alarming picture of the impact humans have had on the earth.

The research was carried out to determine how the actions of humans over the past 500 years have affected the extinction rates of vertebrates: mammals, fish, birds, reptiles and amphibians. And the findings show an alarming accelerated rate of species loss in the past two hundred years.

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

The last comparable event in terms of species extinction was 65 million years ago when the dinosaurs were wiped out — likely by a large meteor.

The finding were published in the journal of Science Advances and has added fuel to the fire for those warning of future catastrophe. The research echoes similar warnings from a report published by Duke University in 2014.

“These estimates reveal an exceptionally rapid loss of biodiversity over the last few centuries, indicating that a sixth mass extinction is already under way,” said the authors of the paper.

“Averting a dramatic decay of biodiversity and the subsequent loss of ecosystem services is still possible through intensified conservation efforts, but that window of opportunity is rapidly closing.”

The analysis is based on documented extinctions of vertebrates, or animals with internal skeletons such as frogs, reptiles and tigers, from fossil records and other historical data.

The modern rate of species loss was compared to the “natural rates of species disappearance before human activity dominated.”

It can be difficult to estimate this rate, also known as the background rate, since humans don’t know exactly what happened throughout the course of Earth’s 4.5 billion year history.

For the study, researchers used a past extinction rate that was twice as high as widely used estimates.

If the past rate was two mammal extinctions per 10,000 species per 100 years, then the “average rate of vertebrate species loss over the last century is up to 114 times higher than it would be without human activity, even when relying on the most conservative estimates of species extinction,” said the study.

“We emphasise that our calculations very likely underestimate the severity of the extinction crisis because our aim was to place a realistic lower bound on humanity’s impact on biodiversity.”

The causes of species loss range from climate change to pollution to deforestation and more.

According to the International Union for Conservation of Nature, about 41 per cent of all amphibian species and 26 per cent of all mammals are threatened with extinction.

“There are examples of species all over the world that are essentially the walking dead,” said co-author Paul Ehrlich of Stanford.

The study called for “rapid, greatly intensified efforts to conserve already threatened species, and to alleviate pressures on their populations — notably habitat loss, over-exploitation for economic gain and climate change.”