AFP Yahoo News 7 Jun 12;
Climate change, population growth and environmental destruction could cause a collapse of the ecosystem just a few generations from now, scientists warned on Wednesday in the journal Nature.
The paper by 22 top researchers said a "tipping point" by which the biosphere goes into swift and irreversible change, with potentially cataclysmic impacts for humans, could occur as early as this century.
The warning contrasts with a mainstream view among scientists that environmental collapse would be gradual and take centuries.
The study appears ahead of the June 20-22 UN Conference on Sustainable Development, the 20-year followup to the Earth Summit that set down priorities for protecting the environment.
The Nature paper, written by biologists, ecologists, geologists and palaeontologists from three continents, compared the biological impact of past episodes of global change with what is happening today.
The factors in today's equation include a world population that is set to rise from seven billion to around 9.3 billion by mid-century and global warming that will outstrip the UN target of two degrees Celsius (3.6 degrees Fahrenheit).
The team determined that once 50-90 percent of small-scale ecosystems become altered, the entire eco-web tips over into a new state, characterised especially by species extinctions.
Once the shift happens, it cannot be reversed.
To support today's population, about 43 percent of Earth's ice-free land surface is being used for farming or habitation, according to the study.
On current trends, the 50 percent mark will be reached by 2025, a point the scientists said is worryingly close to the tipping point.
If that happened, collapse would entail a shocking disruption for the world's food supply, with bread-basket regions curtailed in their ability to grow corn, wheat, rice, fodder and other essential crops.
"It really will be a new world, biologically, at that point," said lead author Anthony Barnosky, a professor of integrative biology at the University of California in Berkeley.
"The data suggests that there will be a reduction in biodiversity and severe impacts on much of what we depend on to sustain our quality of life, including, for example, fisheries, agriculture, forest products and clean water. This could happen within just a few generations."
The authors stressed it was unclear when this feared tipover would happen, given blanks in knowledge about the phenomenon.
And they said there were plenty of solutions -- such as ending unsustainable patterns of growth and resource waste -- that mean it is not inevitable.
"In a nutshell, humans have not done anything really important to stave off the worst because the social structures for doing something just aren't there," said Arne Mooers, a professor of biodiversity at Simon Fraser University in Canada's British Columbia.
"My colleagues who study climate-induced changes through the Earth's history are more than pretty worried," he said in a press release. "In fact, some are terrified."
Past shifts examined in the study included the end of the last Ice Age, between 14,000 and 11,000 years ago, and five species mass extinctions which occurred around 443 million, 359 million, 251 million, 200 million and 65 million years ago.
Earth today is vulnerable to fast change because of the growing connectedness between ecosystems, voracious use of resources and an unprecedented surge in greenhouse gases, the authors concluded.
In a report on Wednesday issued ahead of the "Rio+20" summit, the UN Environment Programme (UNEP) warned that burgeoning populations and unsustainable patterns of growth were driving Earth towards "unprecedented" eco-damage.
Tipping Point? Earth Headed for Catastrophic Collapse, Researchers Warn
Stephanie Pappas LiveScience.com Yahoo News 7 Jun 12;
Earth is rapidly headed toward a catastrophic breakdown if humans don't get their act together, according to an international group of scientists.
Writing Wednesday (June 6) in the journal Nature, the researchers warn that the world is headed toward a tipping point marked by extinctions and unpredictable changes on a scale not seen since the glaciers retreated 12,000 years ago.
"There is a very high possibility that by the end of the century, the Earth is going to be a very different place," study researcher Anthony Barnosky told LiveScience. Barnosky, a professor of integrative biology from the University of California, Berkeley, joined a group of 17 other scientists to warn that this new planet might not be a pleasant place to live.
"You can envision these state changes as a fast period of adjustment where we get pushed through the eye of the needle," Barnosky said. "As we're going through the eye of the needle, that's when we see political strife, economic strife, war and famine." [Top 10 Ways to Destroy Earth]
The danger of tipping
Barnosky and his colleagues reviewed research on climate change, ecology and Earth's tipping points that break the camel's back, so to speak. At certain thresholds, putting more pressure on the environment leads to a point of no return, Barnosky said. Suddenly, the planet responds in unpredictable ways, triggering major global transitions.
The most recent example of one of these transitions is the end of the last glacial period. Within not much more than 3,000 years, the Earth went from being 30 percent covered in ice to its present, nearly ice-free condition. Most extinctions and ecological changes (goodbye, woolly mammoths) occurred in just 1,600 years. Earth's biodiversity still has not recovered to what it was.
Today, Barnosky said, humans are causing changes even faster than the natural ones that pushed back the glaciers — and the changes are bigger. Driven by a 35 percent increase in atmospheric carbon dioxide since the start of the Industrial Revolution, global temperatures are rising faster than they did back then, Barnosky said. Likewise, humans have completely transformed 43 percent of Earth's land surface for cities and agriculture, compared with the 30 percent land surface transition that occurred at the end of the last glacial period. Meanwhile, the human population has exploded, putting ever more pressure on existing resources. [7 Billion Population Milestones]
"Every change we look at that we have accomplished in the past couple of centuries is actually more than what preceded one of these major state changes in the past," Barnosky said.
Backing away from the ledge
The results are difficult to predict, because tipping points, by their definition, take the planet into uncharted territory. Based on past transitions, Barnosky and his colleagues predict a major loss of species (during the end of the last glacial period, half of the large-bodied mammal species in the world disappeared), as well as changes in the makeup of species in various communities on the local level. Meanwhile, humans may well be knotting our own noose as we burn through Earth's resources.
"These ecological systems actually give us our life support, our crops, our fisheries, clean water," Barnosky said. As resources shift from one nation to another, political instability can easily follow.
Pulling back from the ledge will require international cooperation, Barnosky said. Under business-as-usual conditions, humankind will be using 50 percent of the land surface on the planet by 2025. It seems unavoidable that the human population will reach 9 billion by 2050, so we'll have to become more efficient to sustain ourselves, he said. That means more efficient energy use and energy production, a greater focus on renewable resources, and a need to save species and habitat today for future generations.
"My bottom line is that I want the world in 50 to 100 years to be at least as good as it is now for my children and their children, and I think most people would say the same," Barnosky said. "We're at a crossroads where if we choose to do nothing we really do face these tipping points and a less-good future for our immediate descendents."
