Scientists have identified early warning signs of rising ocean temperatures which threaten to drain Australia's Great Barrier Reef of its vibrant colors.
SYDNEY, Australia Scientists have identified early warning signs of rising ocean temperatures which threaten to drain Australia's Great Barrier Reef of its vibrant colors.
Coral bleaching -- when colorful reefs turn white -- occurs when the water temperature gets so high that it kills the algae which populate and build the corals. Researchers have warned that higher ocean temperatures caused by global warming could kill off most of the coral in the Great Barrier Reef -- the world's largest chain of living coral -- by 2050.
Australia's last major coral bleaching episode occurred in 2002, and damaged about 55 percent of the coral systems in the Great Barrier Reef, marine scientist Ray Berkelmans said Tuesday.
The Great Barrier Reef stretches for almost 2,000 kilometers (1,200 miles) along most of the Queensland state coast, and is one of Australia's most popular tourist spots.
Berkelmans -- who has been tracking ocean temperatures for 12 years -- said certain patterns have emerged that can help scientists predict bleaching episodes months before they occur. Previously, scientists could only track bleaching events as they happened, he said.
"We've found unusually intense cold water, (welling up) at the edge of the continental shelf, signals a change in tropical ocean currents and weather patterns which are then usually followed by bleaching," Berkelmans said in a statement.
The changing ocean currents can move warmer-than-usual water over the coral reefs.
Berkelmans said present conditions in the Coral Sea and western Pacific were "teetering on a knife-edge" with temperatures and current patterns dangerously close to those that have preceded bleaching in the past.
"If these conditions continue through December we'll be very concerned," he said.
Despite the warnings about rising ocean temperatures, Australia has refused to sign the Kyoto pact aimed at reducing greenhouse gas emissions believed to cause global warming. The United States has also rejected the protocol, saying the different levels of carbon dioxide reductions assigned to wealthy and developing countries are unfair.
Source: Associated Press