World's sixth mass extinction may be underway - study

A A A

Mankind may have unleashed the sixth known mass extinction in Earth's history, according to a paper released on Wednesday by the science journal Nature.

Over the past 540 million years, five mega-wipeouts of species have occurred through naturally-induced events.

But the new threat is man-made, inflicted by habitation loss, over-hunting, over-fishing, the spread of germs and viruses and introduced species and by climate change caused by fossil-fuel greenhouse gases, says the study.

Evidence from fossils suggests that in the "Big Five" extinctions, at least 75 percent of all animal species were destroyed.

Palaeobiologists at the University of California at Berkeley looked at the state of biodiversity today, using the world's mammal species as a barometer.

Until mankind's big expansion some 500 years ago, mammal extinctions were very rare: on average, just two species died out every million years.

But in the last five centuries, at least 80 out of 5,570 mammal species have bitten the dust, providing a clear warning of the peril to biodiversity.

"It looks like modern extinction rates resemble mass extinction rates, even after setting a high bar for defining 'mass extinction," said researcher Anthony Barnosky.

This picture is supported by the outlook for mammals in the "critically endangered" and "currently threatened" categories of the Red List of biodiversity compiled by the International Union for Conservation of Nature (IUCN).

On the assumption that these species are wiped out and biodiversity loss continues unchecked, "the sixth mass extinction could arrive within as little as three to 22 centuries," said Barnosky.

Compared with nearly all the previous extinctions this would be fast-track.

Four of the "Big Five" events unfolded on scales estimated at hundreds of thousands to millions of years, inflicted in the main by naturally-caused global warming or cooling.

The most abrupt extinction came at the end of the Cretaceous, some 65 million years ago when a comet or asteroid slammed into the Yucatan peninsula, in modern-day Mexico, causing firestorms whose dust cooled the planet.

An estimated 76 percent of species were killed, including the dinosaurs.

The authors admitted to weaknesses in the study. They acknowledged that the fossil record is far from complete, that mammals provide an imperfect benchmark of Earth's biodiversity and further work is needed to confirm their suspicions.

But they described their estimates as conservative and warned a large-scale extinction would have an impact on a timescale beyond human imagining.

"Recovery of biodiversity will not occur on any timeframe meaningful to people," said the study.

"Evolution of new species typically takes at least hundreds of thousands of years, and recovery from mass extinction episodes probably occurs on timescales encompassing millions of years."

Even so, they stressed, there is room for hope.

"So far, only one to two percent of all species have gone gone extinct in the groups we can look at clearly, so by those numbers, it looks like we are not far down the road to extinction. We still have a lot of Earth's biota to save," Barnosky said.

Even so, "it's very important to devote resources and legislation toward species conservation if we don't want to be the species whose activity caused a mass extinction."

Asked for an independent comment, French biologist Gilles Boeuf, president of the Museum of Natural History in Paris, said the question of a new extinction was first raised in 2002.

So far, scientists have identified 1.9 million species, and between 16,000 and 18,000 new ones, essentially microscopic, are documented each year.

"At this rate, it will take us a thousand years to record all of Earth's biodiversity, which is probably between 15 and 30 million species" said Boeuf.

"But at the rate things are going, by the end of this century, we may well have wiped out half of them, especially in tropical forests and coral reefs."

News
people'It can last and it's terrifying'
News
people Emma Watson addresses celebrity nude photo leak
News
Katie Hopkins appearing on 'This Morning' after she purposefully put on 4 stone.
peopleKatie Hopkins breaks down in tears over weight gain challenge
Sport
Alexis Sanchez, Radamel Falcao, Diego Costa and Mario Balotelli
football
PROMOTED VIDEO
Have you tried new the Independent Digital Edition apps?
Sport
Danny Welbeck's Manchester United future is in doubt
footballGunners confirm signing from Manchester United
News
i100
Arts and Entertainment
Olivia Colman topped the list of the 30 most influential females in broadcasting
tv
Life and Style
techIf those brochure kitchens look a little too perfect to be true, well, that’s probably because they are
News
Kelly Brook
peopleA spokesperson said the support group was 'extremely disappointed'
Sport
Andy Murray celebrates a shot while playing Jo-Wilfried Tsonga
TennisWin sets up blockbuster US Open quarter-final against Djokovic
Arts and Entertainment
Hare’s a riddle: Kit Williams with the treasure linked to Masquerade
booksRiddling trilogy could net you $3m
Arts and Entertainment
Alex Kapranos of Franz Ferdinand performs live
music Pro-independence show to take place four days before vote
News
news Video - hailed as 'most original' since Benedict Cumberbatch's
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
iJobs Job Widget
iJobs General

SAP Assessor

£26000 Per Annum: The Green Recruitment Company: Job Title: SAP Assessor Job T...

SEN Teacher

Negotiable: Randstad Education Plymouth: SEN Jobs Available Devon

Infrastructure Lead, (Trading, VCE, Converged, Hyper V)

£600 - £900 per day: Harrington Starr: Infrastructure Lead, (Trading infrastru...

Software Solution Technician - Peterborough - up to £21,000

£20000 - £21000 per annum + Training: Ashdown Group: Graduate Software Solutio...

Day In a Page

'I’ll tell you what I would not serve - lamb and potatoes': US ambassador hits out at stodgy British food served at diplomatic dinners

'I’ll tell you what I would not serve - lamb and potatoes'

US ambassador hits out at stodgy British food
Radio Times female powerlist: A 'revolution' in TV gender roles

A 'revolution' in TV gender roles

Inside the Radio Times female powerlist
Endgame: James Frey's literary treasure hunt

James Frey's literary treasure hunt

Riddling trilogy could net you $3m
Fitbit: Because the tingle feels so good

Fitbit: Because the tingle feels so good

What David Sedaris learnt about the world from his fitness tracker
Saudis risk new Muslim division with proposal to move Mohamed’s tomb

Saudis risk new Muslim division with proposal to move Mohamed’s tomb

Second-holiest site in Islam attracts millions of pilgrims each year
Alexander Fury: The designer names to look for at fashion week this season

The big names to look for this fashion week

This week, designers begin to show their spring 2015 collections in New York
Will Self: 'I like Orwell's writing as much as the next talented mediocrity'

'I like Orwell's writing as much as the next talented mediocrity'

Will Self takes aim at Orwell's rules for writing plain English
Meet Afghanistan's middle-class paint-ballers

Meet Afghanistan's middle-class paint-ballers

Toy guns proving a popular diversion in a country flooded with the real thing
Al Pacino wows Venice

Al Pacino wows Venice

Ham among the brilliance as actor premieres two films at festival
Neil Lawson Baker interview: ‘I’ve gained so much from art. It’s only right to give something back’.

Neil Lawson Baker interview

‘I’ve gained so much from art. It’s only right to give something back’.
The other Mugabe who is lining up for the Zimbabwean presidency

The other Mugabe who is lining up for the Zimbabwean presidency

Wife of President Robert Mugabe appears to have her sights set on succeeding her husband
The model of a gadget launch: Cultivate an atmosphere of mystery and excitement to sell stuff people didn't realise they needed

The model for a gadget launch

Cultivate an atmosphere of mystery and excitement to sell stuff people didn't realise they needed
Alice Roberts: She's done pretty well, for a boffin without a beard

She's done pretty well, for a boffin without a beard

Alice Roberts talks about her new book on evolution - and why her early TV work drew flak from (mostly male) colleagues
Get well soon, Joan Rivers - an inspiration, whether she likes it or not

Get well soon, Joan Rivers

She is awful. But she's also wonderful, not in spite of but because of the fact she's forever saying appalling things, argues Ellen E Jones
Doctor Who Into the Dalek review: A classic sci-fi adventure with all the spectacle of a blockbuster

A fresh take on an old foe

Doctor Who Into the Dalek more than compensated for last week's nonsensical offering