Coral Reefs
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Coral reefs are beautiful, play host to many other sea creatures, and help fuel fishing and tourism. But corals are under attack. The evidence is mounting that global warming and related events like El Niño are taking a toll on these environmentally sensitive creatures. Hi. I'm Dave Thurlow, and this is the Weather Notebook.

Though they look like plants or rocks, corals are actually tiny animals, with skeletons made of limestone. It's the limestone that gives structure to the vast, colorful reefs. Coral reefs are spread around the world's tropics, locked onto the ocean floor. and they may be the first creatures that global warming has put into real jeopardy. Here's why:

Corals need the sea to be within a very specific range-- from about 76 to 84 degrees. If the water gets warmer, the tiny algae that give color and nutrients to corals, and help build their skeleton, disappear. The coral then turns white. This is called "bleaching" and it puts added stress on corals. While corals can recover from bleaching, they can also die from the disease. In fact, bleaching has become epidemic in the past 20 years as oceans have warmed up. El Niño has done the worst damage.

Three years ago, during the last big El Niño, nearly 16% of all the world's coral reefs, struck by bleaching, were destroyed in a matter of months. Ocean scientists say that by 2010, up to 40 percent of the world's coral reefs may be nothing but dead limestone because of the ocean warming. Scientists warn that the threat to corals could have profound consequences for biodiversity, fisheries and tourism. One expert warned, "The coral reefs are the canary in the mine for global warming. They will go first."

Today's story was written by Bob Henson. The Weather Notebook is a production of the Mount Washington Observatory, sponsored by Suburu, the beauty of All-Wheel-Drive.