Australia’s Great Barrier Reef has very “poor” chances of survival even from moderate climate change and there may be “complete death” of the reef by 2050, a new report has said.

The rate of climate change and the optimum levels of carbon-dioxide in the atmosphere supported by the government would result in “severe mass coral bleaching” and threaten the habitats of key species on the reef, ‘The Age’ said on Thursday, quoting the Reef Outlook Report.

In a series of dire predictions for the World Heritage-listed natural wonder, the report by the Great Barrier Reef Marine Park Authority finds that carbon dioxide in the atmosphere will have to be kept under 400 parts per million (ppm) if important animal species and coral are to have a “low to medium vulnerability to climate change”.

The current level of carbon dioxide in the atmosphere is 387 ppm.

Prime Minister Kevin Rudd has publicly supported a 450 ppm target, a figure also backed recently by the Major Economies Forum that also includes the US and China.

Eminent marine researcher and former chief scientist of the Australian Institute of Marine Science, Charlie Veron, who helped prepare the report, told the daily that the Rudd Government-backed 450 ppm target would result in the “complete death of the reef by 2050”.

The report found if the level of carbon dioxide reaches 450 ppm, as predicted for 2035, it would result in “severe mass bleaching” and destroy the reef’s ability to grow new coral.

“Rudd would not be supporting the 450 target if he knew the facts,” Veron said, adding “This isn’t a theory -- all the science is incredibly concrete now and it is backed by everybody in the coral research field.” Meanwhile, World Wildlife Fund spokesperson Nick Heath said the report that showed climate change has already affected levels of calcification -- a process that helps grow and strengthen coral -- which have collapsed dramatically since 1980 as the ocean around the reef has become more warm and acidic.