Most of the coral reefs of the world's oceans will disappear within 30 to 50 years, a marine biologist warned yesterday.
Rupert Ormond, director of the university marine biological station at Millport in Scotland, told the British Association science festival in Glasgow that global warming would raise ocean temperatures to levels that would bleach the great reefs of the Pacific and Indian oceans, the Caribbean and the Red Sea.
Corals are animals that live in symbiosis with light-fixing algae. They colonize shallow coasts and their bones form the limestone platforms that form atolls, enclose lagoons and protect shorelines. They also become habitats for some of the richest collections of creatures on the planet.
Ten years ago, the greatest threat to reefs were pollution from rivers and eruptions of coral-eating starfish. There are now 1,300 marine parks managing the impacts of tourism and overfishing, Dr Ormond said.
But corals are sensitive to changes in sea temperature. In 1998, at the height of a sudden natural surge in temperature, an El Nino, as much as 90% of the coral in the tropical Indian ocean was killed by bleaching.
"This whitening and then death of corals began to be known in a few areas in the 1980s. I became involved in 1997-98 when there was extremely widespread coral bleaching around all the oceans in the tropics," he said.
More than 60 countries experienced coral bleaching. The latest evidence showed overwhelmingly that the bleaching was due to a steady, almost inevitable rise in ocean temperatures, now climbing at the rate of 1-2C every 100 years.
"It explains why to begin with we only saw these events in El Nino years, when the ocean temperatures tend to be warmest... Within 10 to 20 years we will get massive bleaching on a wide scale almost every year. One can predict, looking at those figures, that maybe within 50 years there will be very little left of corals in coral reef countries.
"Frankly, I find the whole prognosis extremely gloomy. I cannot see what can be done, given that there is something like a 50 year time lag between us trying to control carbon dioxide emissions and the temperature of the oceans beginning to drop," he said.
"Reefs are not just attractive places to visit and fun to dive on, they are seen as critical service providers in four main areas: fisheries, tourism, biodiversity and coastal protection, and just as an example it is reckoned that some $100m a year is spent by people in the wider Caribbean. In Egypt where I do a lot of my work there are 2m tourists a year visiting the marine national parks that have reefs."
NASA researchers said yesterday the growing season in Europe and Asia was now 18 days longer than two decades ago. Evidence from satellites showed trees were going into leaf a week earlier in spring, and autumn was arriving 10 days later.
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