As Coral Bleaching Goes Global, Scientists Fear Worst Is Yet to Come
The longest and most widespread coral bleaching event on record has reached reefs near at least 38 countries and island groups, according to the latest report from NOAA's Coral Reef Watch and other research. Parts of many coral reefs have died, becoming ghostly underwater graveyards. They are perhaps the starkest reminders—like the melting Arctic—that a thickening blanket of greenhouse gases is irrevocably changing the face of the Earth.
Reefs are not only beautiful to behold, they also play a key role in ocean ecosystems. When the surrounding water gets too warm, corals start to expel symbiotic algae that helps keep them alive and gives them their color. Bleaching in popular tourist spots like the Maldives and Great Barrier Reef has grabbed recent headlines, but reefs in all the world's tropical oceans have been affected.
Coral mortality has reportedly been as high as 50 percent along previously healthy sections of Australia's Great Barrier Reef. There was even higher mortality around small islands in the central Pacific, in the pool of water overheated by the recent strong El Niño.