Enjoy diving the world's corals - because your grandchildren may not have the opportunity. Scientists have warned that, through climate change, the world's corals could start disappearing quickly in the next 35 to 70 years.

Speaking at a climate-change conference in Exeter at the beginning of February, scientists explained that the world's seas are becoming ever more acidic - and that many species of coral will eventually become unable to grow.

It has been calculated that nearly half of all man-made carbon dioxide emissions are absorbed by the sea, where they convert to carbonic acid. This can harm any organism which employs calcium to form a shell or skeleton.

Corals, sea urchins and, crucially, plankton - which underpin the food chain for many sea creatures - are just some of the species that could suffer a "severe impact", said Carol Turley, Head of Science at Plymouth Marine Laboratory.

But corals would be particularly vulnerable. Within 35 to 70 years, Turley said, seas could become too acidic for coral reefs to survive.

"This is a rapid change that the world, and the organisms in the sea, have not seen for hundreds of thousands of years, if not millions," she told delegates. "There is a very urgent need to do more research."

Crabs and lobsters, which build shells from a different material, chitin, might be less prone to harm. But fish such as cod, which consume plankton or shellfish that rely on calcium carbonate to grow, could be badly affected.

And, with numbers of fish greatly reduced, jellyfish could enjoy a renaissance. "The whole composition of life in the oceans will have changed," said Turley.

A team from Jerusalem's Hebrew University told how they tested reefs around Eilat in the Red Sea. They found that the more acidic the water, the more slowly the corals grew.

They expected carbon dioxide emissions and carbonic acid levels to continue rising, until a point of no return was reached for corals.

The team's leader, Professor Jonathan Erez, later told BBC2's Newsnight programme: "This ecosystem, which is the most productive and diverse in the ocean, is going to disappear as an ecosystem.

"The individual components may survive here and there but, as an ecosystem, our grandchildren will not see coral reefs any more."

In Exeter it was concluded that more urgent attention should be paid to replacing fossil fuels with other sources of energy.

The Avoiding Dangerous Climate Change conference was sponsored by the UK Department of Environment, Food and Rural Affairs.

Related links
Avoiding Dangerous Climate Change home site
Fish stocks and coral reefs under pressure
Coral may survive global warming, but not CO2 increase
Coral reef study shows link between fishing and starfish attacks
Great Barrier Reef coral will be gone in 50 years
Coral reefs threat
Climate change could reduce coral growth
Coral faces a bleach future

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