The Australian, 14th December 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.

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