June 8, 2012-By Agence France-Presse
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. For the rest of the story Go To Original