WASHINGTON (AP) -- Only about 30 percent of the world's coral reefs are healthy, down from 41 percent two years ago, according to a study released Monday that lists global warming as the top threat.
The study found as many as one-fifth of the world's coral reefs have been destroyed. Another half are damaged but could be saved, it said.
Coral reefs are among the oldest and most diverse forms of life. They provide food and shelter to fish and protect shores from erosion.
While covering less than 1 percent of the earth's surface, they help drive the food chains and economies of many on the planet, with $375 billion in economic benefits globally, according to the study by 240 scientists in 96 countries.
After global warming -- blamed for higher water temperatures and carbon dioxide concentrations -- threats to the reefs include coral disease, overfishing, coastal development and pollution runoff from land-based sources.
"Reefs need our help, but they're not going to go extinct," said Clive Wilkinson, the study's lead author and coordinator of the Global Coral Reef Monitoring Network. Still, he said, it's crucial to "raise the level of political will" to help reefs around the world.
"We know they're degrading fast, we know what the problems are, we know how to fix them," Wilkinson said at news conference by the Swiss-based World Worldlife Fund. "We've just got to do it."
Destruction or threats to 70 percent of the coral reefs represent a sharp rise from 59 percent in the last study in 2002.
About 65 percent of the Persian Gulf's reefs have been destroyed, the report said. Next in terms of damage are reefs off South and Southeast Asia, where 45 percent and 38 percent, respectively, have been destroyed.
Retired Navy Vice Admiral Conrad Lautenbacher, a Commerce Department undersecretary who heads the National Oceanic and Atmospheric Administration, called reefs a global issue.
"It is not just a nice thing from an environmental perspective," Lautenbacher said. "It is essential to life on earth."
John Turner, assistant secretary of state for oceans and international environmental and scientific affairs, called the report "a wake-up call" and said it would be circulated to U.S. diplomats overseas.
A more positive development is the recovery of about two-fifths of the reefs seriously damaged by an unprecedented coral "bleaching" from unusually warm waters in 1998. About 16 percent of global reefs had been damaged by the bleaching.
Most of the reefs that have recovered are in the Indian Ocean, are part of the Great Barrier Reef off Australia's coast or are in the western Pacific, particularly around Palau. Australia this year put as much as a third of both its Great Barrier Reef and Ningaloo Reef marine park off limits to fishing.
The Caribbean has lost 80 to 98 percent of its elkhorn and staghorn coral, two of the region's most common species, the scientists said, suggesting the United States should look at listing them as endangered species. A petition from an environmental group, the Center for Biological Diversity, to do that is being considered by the Bush administration.
The administration's efforts so far to protect coral reefs include improving monitoring and satellite surveillance, agreeing to Geneva-based treaty restrictions on international trade in coral reefs and passing out $10 million in grants, Lautenbacher said.
The administration is also considering creating a national marine sanctuary and banning commercial fishing in the Northwestern Hawaiian Islands to protect the chain's delicate reefs. A decision is expected by the end of 2005, Lautenbacher said.
