Coral reefs under climate threat

Published on Tuesday 23 February 2010 21:42

THE world's coral reefs face being eaten away by the end of the century as greenhouse gases turn the oceans more acidic, new research suggests.

Scientists predict when the amount of carbon dioxide in the atmosphere reaches twice its pre-industrial level, reefs will stop growing and start to disintegrate.

If current trends continue, coral reefs – formed from the hard skeletons of millions of simple marine organisms called polyps – could start to vanish.

Research leader Dr Jacob Silverman, from the Carnegie Institution in Washington DC, said: "These ecosystems, which harbour the highest diversity of marine life in the oceans, may be severely reduced within less than 100 years."

Reef-building corals are highly sensitive to the acidity and temperature of the seawater in which they grow, Dr Silverman told the annual meeting of the American Association for the Advancement of Science in San Diego.

Oceans soak up greenhouse gas from the atmosphere, but in doing so become more acidic. The gas forms carbonic acid when it reacts with saltwater.

When the acid levels rise too high, it prevents coral from extracting minerals from seawater to build up their hard skeletons. Temperature also affects this process.

Mass bleaching events were extremely rare 30 years ago, but had become increasingly common in recent years, researcher Dr Simon Donner said.

In 2006, severe bleaching struck the southern part of Australia's Great Barrier Reef, the world's largest coral reef system, but it has since recovered.