Scientists warn: do not trespass on global boundaries
Thu Sep 24 05:11:34 EST 2009
Wed Sep 23 19:11:34 UTC 2009
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CANBERRA, Sept 24 AAP - A group of international scientists has marked nine clear lines in the sand that must not be crossed if humans are serious about saving the planet.
The boundaries for climate change, fresh water use, pollution and ozone depletion among others, if transgressed, could bring the world into a new era of decline, the scientists warn.
The global study brought together 28 researchers, including three Australians, and outlines exactly what levels are required to keep the world sustainable.
For climate change, it's a carbon concentration of 350 parts per million; for biodiversity, it's the loss of only 10 species per million each year.
The other areas include the stratospheric ozone, land-use change, ocean acidification, fresh water distribution, the nitrogen and phosphorus cycles, aerosol loading and chemical pollution.
The scientists hope it will provide a blueprint for humans in their quest for a more sustainable planet.
"We are entering the Anthropocene, a new geological era in which our activities are threatening the Earth's capacity to regulate itself," said report co-author Professor Will Steffen, a director of the Climate Change Institute at the Australian National University in Canberra.
"The expanding human enterprise could undermine the resilience of the Holocene state, which would otherwise continue for thousands of years into the future.
"Here we have a challenge ... on how can we get our act together?"
The only problem is humans may have already passed the boundaries for three of the nine areas.
Global leaders are looking at reducing carbon emissions to 450 parts per million, well above the scientists' recommended levels.
And 10 extinctions per million species a year signals a massive departure from the 100 we're already losing.
It doesn't mean the race is lost, said Prof Steffen, who admitted the figures weren't perfect.
"We're quick to admit that our knowledge is very incomplete in this area and we hope that rather than people arguing about whether we've got the figure right, we trigger a lot more research," he said.
It was about identifying the issues at stake and increasing awareness, he said.
The study has been published in the latest edition of Nature.
