Coral bleaching alert levels over the past 30 days.
Credit: Coral Reef Watch
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This is the third global bleaching event on record. The others were in 1998 and 2010, both El Niño years. El Niño, which is marked by warmer than normal waters in the tropical Pacific, has certainly played a role. The steady background creep of ocean warming due to climate change, however, is also an important factor. More than 90 percent of the accumulated heat due to climate change is ending up in the oceans and its effects are being acutely felt.
The prolonged exposure to high water temperatures has left many reefs in critical shape. The warm water causes corals to expel the algae they rely on to grow, leaving ghostly white skeletons in the place of thriving coral communities.
Coral bleaching forecast for March-June.
Credit: Coral Reef Watch
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Coral there have been subjected to some of the most stressful conditions anywhere in the world. Specifically, El Niño sent water temperatures as high as 88°F, or about 6°F above normal, in the region. That extended period of stress had already killed off a wide array of corals when Kim Cobb, a coral expert at Georgia Tech, visited the reef in November during peak El Niño heat.
And though waters are cooling as El Niño ebbs, Cobb is expecting to see even more devastation when she returns to Christmas Island next month. She's using crowdfunding for the trip because of the rapid response nature of the work and the wealth of information she and other scientists can learn from.
Airport Reef in American Samoa at the height of a bleaching event in February 2015.
Credit: XL Catlin Seaview Survey
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The data Cobb plans to collect will provide valuable insight into which corals survive this extreme heat event. With climate change expected to keep warming oceans, those types of insights could be key to conservation efforts, not just at Christmas Island but around the world.
And while Christmas Island should experience a reprieve with oceans returning to normal temperatures around the region later this year, other areas will continue to feel the heat. The odds are increasing for a La Niña event later this year. While that means cooler-than-normal waters for the eastern and central tropical Pacific, it ramps up temperatures in the western edge of the basin around Indonesia and the Papua New Guinea.
That area is known as the Coral Triangle, an ecologically crucial spot for coral, fish, turtles and other sea creatures. It's already under threat from the current global coral bleaching event and could face even higher risks if La Niña materializes.
Links
- These Coral Reefs Are a 'Crystal Ball' For Future Change
- Clues in Coral Hint at Looming Temperature Spike
- Hot Oceans Are Killing Coral Reefs Around the World
- Bleak Picture of Great Barrier Reef's Changing Chemistry
- Paris Pact Promotes But Complicates Carbon Trading
- Study Reveals Stunning Acceleration of Sea Level Rise
- The Human Fingerprints on Coastal Floods
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