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The Australian , December 14, 2007

IT is probably too late to save the Great Barrier Reef and other
coral reefs from global warming.

Even if governments implement far-reaching measures to cut greenhouse
gas emissions, they will not prevent the annihilation of coral reefs
around the world.

These are the conclusions of analysis by leading marine scientists to
be published today in the prestigious journal Science.

"There is a terrible future in front of us for the reefs," said
Canada-based United Nations University professor Peter Sale, one of
17 authors from seven nations of the Science paper.

On Wednesday, Kevin Rudd told the UN's Bali climate change conference
that global warming was threatening Australian natural wonders such
as the Great Barrier Reef, Kakadu National Park and rainforests,
killing rivers and exposing people to more frequent and ferocious bushfires.

The scientists present three scenarios for the future of coral reefs
- the world's largest lifeforms - under different climatic conditions.

If current conditions continue, with the stabilisation of
temperatures and emissions at today's level of 380 parts per million,
reefs will survive but undergo fundamental changes.

However, scientists agree that stabilisation of current conditions is
not possible. The paper warns that if emissions rise to between 450
and 500ppm, with an associated temperature rise of 2C by 2050 - the
most optimistic outcome predicted by the landmark study by British
economist Nicholas Stern - reefs will suffer "vastly reduced habitat
complexity and loss of biodiversity".

But if they rise above 500ppm, the minimum emission level forecast by
the UN's Intergovernmental Panel on Climage Change by 2050, reefs
will become "rapidly eroding rubble banks".
"These changes will reduce coral reef ecosystems to crumbling
frameworks with few calcareous corals," the paper says.

"It is clear that coral reefs as we know them today would be extremely rare."

The scientists determined that the concentration of carbon monoxide
in the earth's atmosphere of 380ppm was 80ppm higher than it has been
for 740,000 years, and probably for as long as 20 million years.

Professor Sale, who is in Brisbane this week for a World
Bank-sponsored marine science conference, said there was no point
speculating about the outcome for reefs in the worst-case scenarios
outlined by the Stern and IPCC reviews, of temperature rises as high
as 6C. "In the best-case predictions, with temperature rises of 2C by
2050, the outlook can hardly be more dire," he said.

However, he said some damage could be averted if radical measures
were introduced to curb emissions. "There is a ray of hope, but it is
fading fast."

Climate change sceptic Bob Carter, a James Cook University
researcher, said while he was not familiar with the Science paper,
caution needed to be exercised about "alarmist" climate modelling.
"Too often these climate models are basically PlayStations which have
not been validated scientifically," Dr Carter said.

But the lead author of the Science paper, University of Queensland
professor Ove Hoegh-Guldberg, said the $7billion Great Barrier Reef
tourism industry was at risk.

"With conservative estimates predicting emission levels exceeding
500ppm, coral reefs will dwindle into insignificance," Professor
Hoegh-Guldberg said.

"These changes dwarf anything that happened in the Ice Age
transitions and they are happening faster than Stern and the IPCC
predicted. The outlook is very grim."

Another author of the paper, World Bank marine adviser Marea
Hatziolos, said the collapse of coral reefs would destroy the
livelihood of 100 million people.

Food supplies to millions more would be reduced; in Asia, reefs
supply 25 per cent of fish, feeding one billion people.

Paul R. Ehrlich
Bing Professor of Population Studies
President, Center for Conservation Biology
Department of Biological Sciences
Stanford University, Stanford, CA 94305-5020

Jimmy Sjöblom
Jimmy Sjöblom 2007-12-17 09:48:58
71 postningar


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