THE Great Barrier Reef's chances of survival from even moderate climate change is poor and "catastrophic damage" may not be avoided, the first Reef Outlook Report has found.
And it concludes that the rate of climate change backed by the Federal Government would result in "severe" coral bleaching and threaten the habitats of key species on the reef.
The five-year study by the Great Barrier Reef Marine Park Authority was released yesterday by the Environment Minister, Peter Garrett, who used the occasion to announce a new water-quality plan for the reef.
In a series of dire predictions for the Australian icon, the report finds that carbon in the atmosphere will have to be kept to under 400 parts per million (ppm) if animal species and coral are to have a low to medium vulnerability to climate change.
The current level of carbon in the atmosphere is 387 ppm.
The Prime Minister, Kevin Rudd, has on several occasions publicly supported a 450 ppm target for carbon in the atmosphere - a figure also backed recently by the Major Economies Forum that includes the United States and China.
The report finds if carbon reaches 450 ppm in the atmosphere, which is predicted for 2035, it would result in "severe mass bleaching" and destroy the reef's ability to grow new coral.
An eminent marine researcher and the former chief scientist of the Australian Institute of Marine Science, Charlie Veron, who helped to prepare the report, said the Rudd Government-backed 450 ppm target would result in the complete death of the reef by 2050.
"Mr Rudd would not be supporting the 450 target if he knew the facts," Mr Veron said yesterday. "This isn't a theory - all the science is incredibly concrete now and it is backed by everybody in the coral research field."
A spokesman for WWF, Nick Heath, said the report showed climate change had already affected levels of calcification, a process which helps grow and strengthen coral, which have collapsed dramatically since 1980 as the ocean around the reef warms and becomes more acidic.
Mr Garrett said the report found that the Barrier Reef continued to be one of the world's healthiest coral systems, but that the emerging threat from climate change required action on global warming.
"The world's only got one Great Barrier Reef, Australia has only got one Great Barrier Reef. It is our most important natural environmental asset," Mr Garrett said.
On the back of yesterday's release Mr Garrett and the Queensland Premier, Anna Bligh, committed to a binding target to cut the amount of pesticides and other agricultural run-off onto the reef by half.
The report found one-third of the reef is exposed to agricultural run-off, which hurts coral and marine life.
The Rudd Government has spent $325 million to improve the health of the reef, including $76 million to work with nearby farmers to limit agricultural runoff. Yesterday's release is the first of what will be a five-yearly review of the reef's health.
The report also found that the general health of marine life in the reef system is strong with no extinctions, but some species, including dugongs, turtles and some sharks have seen significant declines in numbers.