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. The study concludes that Earth's creatures are on the brink of a sixth mass extinction, comparable to the one that wiped out the dinosaurs and it calculates that three-quarters of today's animal species could vanish within 300 years.
Species naturally come and go over long periods of time. But what sets a mass extinction apart is that three-quarters of all species vanish 
quickly. Earth has already endured five such events over the past 540 million years including the one that wiped out dinosaurs and many other creatures 65 million years ago. Conservationists have warned for years that the world is in the midst of a sixth, human-caused extinction, with species from frogs to birds to tigers threatened by climate change, disease, loss of habitat and competition for resources with nonnative species.
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.
Palaeo-biologists 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.
The baiji dolphin is functionally extinct, orangutans are disappearing and even some species of bats—the most numerous of mammals—are dying out.
"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 is really gloom-and-doom stuff," continues Barnosky of the University of California, Berkeley. "But the good news is we haven't come so far down the road that it's inevitable."
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 time frame 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 the Earth has only
lost "a few (percent) of species, nothing like the 75% we lost in the past, so we still have a lot more out there to save," says Barnosky, who glumly adds, "Walk outside, look around and imagine three-fourths of all the different kinds of life you see gone. Ask yourself if you'd be happy living in that world."
"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 biotic 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."
The silver lining in this dark cloud is that if humans work quickly to protect endangered and threatened species and their habitats now, the mass extinction can be prevented or at least delayed by thousands of years, says Barnosky.
Source:
Canada.com,"World’s sixth mass extinction may be underway: study",accessed March 10, 2011
Washington Post, "Study foresees a rapid and widespread extinction of species", accessed March 10, 2011
Science Now, "Are We in the Middle of a Sixth Mass Extinction?", accessed March 10, 2011
World leaders will next week consider a target for halting extinctions of animals and plants by 2020 that many experts rate impossibly ambitious given mounting threats such as climate change and loss of habitats.
"Biodiversity losses are accelerating," said Anne Larigauderie, executive
director of the Paris-based Diversitas Secretariat (at right), which groups international scientists and reckons the goal laid out in a draft U.N. plan is out of reach for 2020.
Experts say that at least half of the world’s current species will be completely gone by the end of the century. Wild plant-life is also disappearing. Of the 45,000 species evaluated by the International Union for Conservation of Nature in 2008, 17,000 faced at least a high risk of extinction in the wild. The list of species in trouble is extensive and includes orangutans, rhinos, tigers, bees, polar bears, chimpanzees, 
blue-finned tuna, etc. Some scientists are predicting that half of all species will go extinct in this century.
At the United Nations headquarters in New York on September 22, nations will discuss how to protect the diversity of plants and animals -- vital to everything from food to fresh water -- after failing to reach a goal set in 2002 of a "significant reduction" in losses by 2010.
The world has made some progress since 2002, such as in expanding protected areas for wildlife. But U.N. studies say extinction rates are running up to 1,000 times higher than those inferred from fossil records in the worst crisis since 
the dinosaurs were wiped out 65 million years ago.
Larigauderie said scientists had been largely left out of defining new goals. "Until we have an organized process we will continue to have these sort of feel-good objectives that we are going to miss again," she said of halting losses by 2020.
A draft U.N. strategic plan for 2020, to be formally adopted at U.N. talks in Japan in October, calls for "effective and urgent action" either "to halt the loss of biodiversity by 2020" or "toward halting the loss of biodiversity" with no deadline.
IMMENSE STRUGGLE
"Our goal has to be to halt the loss of biodiversity," said Achim Steiner (at left), head of the U.N. Environment Program.
"Can we already agree on targets and time-lines that lead us to that over the course of a decade? It will be an immense struggle," he stated while urging tough goals.
Apart from the overall target for 2020, some targets in a draft strategic 
plan are more measurable -- such as an option of "ending overfishing" or "halving" deforestation by 2020.
A rising human population, spread of cities, pollution and global warming are adding to problems that are damaging nature and vital free services ranging from insect pollination of crops to coral reefs that are nurseries for fish stocks.
Environmental group Greenpeace said the world should set the strictest 
possible goals for 2020.
"We favor halting the loss of biodiversity by 2020," said Nathalie Rey of Greenpeace. "We are at a crossroads where we are at a point of no return. You have to stay ambitious."
A U.N. study this year said the world risked "tipping points" of no return such as a drying out of the Amazon rainforest, a build-up of fertilizers that bring dead zones in the oceans or ocean acidification linked to climate change.
The International Union for Conservation of Nature, which groups governments, scientists and environmentalists, believes it is too 
ambitious to set a goal of halting losses by 2020.
It has argued for a vaguer target of "putting in place by 2020 all the necessary policies and actions to prevent further biodiversity loss." Beyond that, it wants a 2050 deadline for conserving and restoring biodiversity.
Source:
Reuters,"World examines "impossible" goal to halt extinctions", accessed September 18, 2010
Facing what many scientists say is the sixth mass extinction in half-a-billion years, our planet urgently needs a "bailout plan" to protect its biodiversity, a top conservation group said Thursday.
Failure to stem the loss of animal and plant species will have dire consequences on human well-being, the International Union for Conservation of Nature (IUCN) warned.
"The gap between the pressure on our natural resources and governments' response to 
the deterioration is widening," said Bill Jackson, the group's deputy director, calling for a 10-year strategy to reverse current trends.
"By ignoring the urgent need for action we stand to pay a much higher price in the long term than the world can afford," he said in a statement.
A fifth of mammals, 30 percent of amphibians, 12 percent of known birds, and more than a quarter of reef-building corals -- the livelihood cornerstone for 500 million people in coastal areas -- face extinction, according to the IUCN's benchmark Red List of Threatened Species.
In 2002, the international community pledged to slow the biodiversity drop off by 2010, and incorporated the target into the United Nations Millennium Development Goals.
But the decline has continued apace, according to a major scientific assessment published last week in the journal Science.
The next opportunity to set new goals and devise a strategy for achieving them will be the October meeting in Nagoya, Japan of the Convention of Biological Diversity.
In preparation, an advisory body of scientists will brainstorm in Nairobi, Kenya starting next week, and formulate recommendations.
Discussions will cover protected areas, inland and marine water 
areas, the impact of climate change, biofuels and invasive species, said the IUCN, a key partner in the deliberations.
"This year we have a one-off opportunity to really bring home to the world the importance of the need to save nature for all life on Earth," said Jane Smart, head of the IUCN's Biodiversity Conservation Group.
"If we don't come up with a big plan now, the planet will not survive," she said.
The IUCN draws together more than 1,000 government and NGO organisations, and 11,000 volunteer scientists from about 160 countries.
Source:
Google News, "World needs 'bailout plan' for species loss: IUCN", accessed May 5, 2010
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. The study concludes that Earth's creatures are on the brink of a sixth mass extinction, comparable to the one that wiped out the dinosaurs and it calculates that three-quarters of today's animal species could vanish within 300 years.
quickly. Earth has already endured five such events over the past 540 million years including the one that wiped out dinosaurs and many other creatures 65 million years ago. Conservationists have warned for years that the world is in the midst of a sixth, human-caused extinction, with species from frogs to birds to tigers threatened by climate change, disease, loss of habitat and competition for resources with nonnative species.
greenhouse gases, says the study.
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.
endangered" and "currently threatened" categories of the Red List of biodiversity compiled by the International Union for Conservation of Nature (IUCN).
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.
lost "a few (percent) of species, nothing like the 75% we lost in the past, so we still have a lot more out there to save," says Barnosky, who glumly adds, "Walk outside, look around and imagine three-fourths of all the different kinds of life you see gone. Ask yourself if you'd be happy living in that world."
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."
