Sabtu, 17 Mei 2008

Change is accelerating in the greenhouse

By : Richard Macey

CLIMATE change enhanced by humans is taking its toll on the world's plants and animals and physical environment much more quickly than previously thought, scientists have warned.

The message from a study was that climate change required an urgent response, said one of the scientists, David Karoly, from the University of Melbourne's school of earth sciences.

The international research team found that many accounts of plants flowering early, birds changing migration habits, and glaciers and mountain snow melting were probably the result of rising greenhouses gases.

"Climate change from greenhouse gases is not only affecting the temperature," Professor Karoly said yesterday.

"It is already affecting ecosystems, and other systems, like glaciers. It is happening earlier than previous studies would have indicated. When you look at the different signals across the globe you can see that message very clearly."

Scientists from the US, the Netherlands, China, Poland, Canada, Chile and Australia reviewed about 80 studies that had looked, for various reasons, at the changing behaviour of plants, animals and physical environmental systems.

The studies looked at changing patterns from 1970 to 2004.

Published today in the journal Nature, the analysis found that patterns documented in only three of the studies "were likely to have been caused by a driving force other than climate change".

Otherwise it was unlikely, very unlikely or exceptionally unlikely that the cause had been another factor, such as changes in the sun's radiance, pollution, land clearing or an invasion by an exotic species.

Professor Karoly, a member of the Wentworth Group of Concerned Scientists, said the impact of climate change was "difficult to see if you only look at one location". But the reviewed studies had examined changes in ecosystems and environments on every populated continent.

If something other than global warming was to blame for the changes observed "you would not expect to get a consistent response from across the whole globe".

He said it was "important for all people to get this message. The urgency of responding to climate change is critical."

Neville Nicholls, a lead author of the Synthesis Report released in November by the UN's Intergovernmental Panel on Climate Change, said: "People sometimes wonder if the warming reported by climate scientists perhaps just reflects cities growing bigger, or changes in the way we measure temperature."

Professor Nicholls, from Monash University's school of geography and environmental science, said: "Yes, Virginia, global warming truly is global."

Another Nature study, of Antarctic ice cores, reports atmospheric greenhouse gas levels are higher than they have been in 800,000 years.

Source : http://www.smh.com.au/news/global-warming

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