World's Coral Reefs Facing Serious Threats

A major new survey of the world's coral reefs finds that they are in trouble. Big trouble.

Overfishing and local pollution continue to grow as threats, and the reefs' long-term existence is in doubt because the world's oceans are gradually getting warmer and more acidic because of human activity.

There's a lot at stake: Coral reefs are spectacular ecosystems, overflowing with diverse and colorful marine life. They're also the source of food and economic sustenance to half a billion people around the world.

"Currently, we find 75 percent of the world's reefs are threatened by a combination of local and global threats," says Lauretta Burke, a senior author of the new report. "By 2030, the percentage will rise to 90 percent. By 2050, virtually all reefs will be threatened," she says.

Many of the risks are familiar and long-standing. At a news conference Wednesday, Burke, of the World Resources Institute, talked about overfishing, and runoff of sewage and sediments from the shore.

"But perhaps the most shortsighted threat to reefs is the use of destructive fishing practices: the use of poisons to stun and capture fish, the use of explosives to kill fish," she says.

The report also folds in global threats. Greenhouse gases pouring into the atmosphere from our tailpipes and chimneys warm the oceans, causing heat stress to corals. Lots of that carbon dioxide also dissolves in the ocean, creating carbonic acid, which can eventually corrode coral and other shell-building animals. Add it all together, and one-third of all coral species are at risk of extinction, says Nancy Knowlton of the Smithsonian Institution's Marine Biology Research Institution.

"This makes corals the most endangered animal on the planet," she says, "even more endangered than frogs, which have gotten a lot of press because of the diseases that have wiped out a lot of frog populations. And of course this is just the corals — it doesn't count all the things that depend on corals."

Dealing With The Threats

"These are dire projections," Burke says. But it doesn't have to be that way: "These results assume no improvement in management, no reduction in local threats, and that we continue on our current trajectory of greenhouse gas emissions."

And that current emissions trajectory gives us a small grace period.

"The tipping point comes sometime between 2040 and 2050, which is not that far away," Knowlton says.

Local threats are potentially easier to deal with, and there has been some progress in that regard. For example, President George W. Bush created vast marine protected areas in the Pacific to preserve reefs in U.S. territorial waters.

"We obviously need more marine protected areas," Knowlton says. "Not just big ones like these, but small ones, local ones in the developing world, where major marine protected areas aren't financially possible, but small protected areas can do a lot of good."

In releasing this report today, the World Resources Institute got help from one of the premiere marine biologists in this country — Jane Lubchenco, who now runs the U.S. National Oceanic and Atmospheric Administration.

"It will take a Herculean effort to reverse the current trajectory and leave healthy ocean ecosystems to our children and our grandchildren," she said.

And nobody sounded too optimistic about that task.