Update: 1:44PM The world has lost 19 per cent of its coral reefs, according to the 2008 global update of the worlds reef status.
The report, released by the Global Coral Reef Monitoring Network, shows if current trends in carbon dioxide emissions continue, many of the remaining reefs may be lost over the next 20 to 40 years.
This will have alarming consequences for some 500 million people who depend on coral reefs for their livelihoods.
Climate change is considered the biggest threat to coral reefs today.
The main climate threats, such as increasing sea surface temperatures and seawater acidification, are being exacerbated by other threats including overfishing, pollution and invasive species.
"If nothing changes, we are looking at a doubling of atmospheric carbon dioxide in less than 50 years," says Carl Gustaf Lundin, Head of the IUCN Global Marine Program, one of the organisations behind the Global Coral Reef Monitoring Network.
"As this carbon is absorbed, the oceans will become more acidic, which is seriously damaging a wide range of marine life from corals to plankton communities and from lobsters to seagrasses."
Encouragingly, 45 per cent of the worlds reefs are currently healthy.
Another sign of hope is the ability of some corals to recover after major bleaching events, caused by warming waters, and to adapt to climate change threats.
However, the report shows that, globally, the downward trend of recent years has not been reversed.
