Islanders threatened by coral destruction

Marine biologists have issued their sternest warning yet about the parlous state of the world's coral reefs and say their destruction could lead to an unprecedented migration of island-dwellers whose homes and livelihoods are in danger of being washed away.

Marine biologists have issued their sternest warning yet about the parlous state of the world's coral reefs and say their destruction could lead to an unprecedented migration of island-dwellers whose homes and livelihoods are in danger of being washed away.

Some governments are now so concerned about the consequences of losing up to half of the world's coral reefs over the next 25 years that they are preparing contingency plans to move millions of people to neighbouring countries.

Warmer sea temperatures, pollution and overfishing are being blamed for the destruction of coral, which acts as an important barrier against the erosion of island coastlines that are already under threat from rising sea levels because of global warming.

Some predictions suggest that rising sea levels will begin to have an impact on low-lying island nations within the next 50 to 100 years, although some scientists believe that the rate of coral destruction and coastal erosion will make this a reality within 30 years.

Ove Hoegh-Guldberg, a marine biologist from the University of Queensland, who has written a report on coral destruction in the western Pacific, said at least three million people from the islands of Tuvalu and Kiribati might have to be relocated to Australia and New Zealand.

"I know that the Australian government is taking this very seriously and that the US State Department is also worried about the long-term socio-economic consequences of these population shifts," Professor Hoegh-Guldberg said.

About 1,500 of the world's leading marine biologists are meeting this week at an international symposium about coral reefs in Bali, Indonesia, where scientists made pessimistic forecasts about the future of coral, which is seen as the undersea version of tropical rainforest; both are rich in wildlife but easily destroyed.

One assessment says that between 50 and 90 per cent of the coral reefs stretching from the east coast of Africa to the west coast of India, including the Maldives and the Seychelles, are now dead or dying.

"There is a very good probability that coral reefs as we know them now will be gone in 30 to 50 years," said Professor Hoegh-Guldberg, who calculates that 26 per cent of the world's coral reefs have already been destroyed.

One of the main problems was identified two years ago when huge tracts of coral suffered "bleaching", whereby the coral organism expels the brightly coloured algae that lives symbiotically in the coral's limestone "skeleton".

The bleaching effect came after one of the most severe El Niño events in recent times when a warm Pacific Ocean current flowing west to east suddenly went into reverse, causing dramatic changes in local climates.

Research published this week in the journal Nature shows that coral growth is intimately connected with El Niño events, which are themselves strongly influenced by average sea temperatures.

Scientists from the University of Colorado studied coral cores drilled from a Pacific atoll that dated back 155 years. They found that the annual coral growth patterns showed sea temperatures became slowly warmer in the first part of the 20th century but underwent a dramatic temperature increase around 1976 and 1977.

El Niño events during the past 25 years have also become stronger and are known to act as powerful forces for the distribution of heat throughout the Pacific and Indian oceans, where much of the coral destruction has taken place.

Professor Hoegh-Guldberg said:"There is no way to explain this coral death event [other] than by global warming... all the marine scientists I know are now really scared by this evidence."