Global Coral Bleaching 2014 -
Global warming combined with a significant El Niño are driving the Earth's third global coral bleaching event. The event, which began in 2014, could extend well into 2017 and is the longest coral bleaching event on record. Due to record warm ocean temperatures, coral reefs from the South Pacific to Hawaii, from western Africa to the Caribbean are losing the symbiotic algae that feed and give them color.
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Great Barrier Reef sees worst coral bleaching ever
Scientists confirmed in late-March 2016 that the global bleaching event which began in 2014 was the worst ever observed in parts of the Great Barrier Reef.
In the northern part of the Great Barrier Reef, only four of the 520 reefs surveyed by coral scientist Terry Hughes in early March 2016 showed no signs of bleaching, and more than 95 percent were in the top two most severe bleaching categories. During a bleaching event in 2002, only 18 percent of reefs experienced such severe bleaching.
By the end of May, scientists found that corals in the Coral Sea region north of Cairns—covering about two-thirds of the Great Barrier Reef—had an average mortality rate of 35 percent, rising to more than 50 percent in areas around Cooktown. Water temperatures in the Coral Sea were record warm in March of this year.
Warming water isn’t the only way greenhouse gas emissions damage corals
The ocean has absorbed an estimated 26 percent of the carbon dioxide (CO2) released into the atmosphere since the start of the Industrial Revolution in 1750. This uptake of CO2 from the atmosphere is a major contributor to the decline in seawater pH known as ocean acidification.
A recent Nature study found that coral reefs grew 7 percent faster under pre-Industrial Revolution pH conditions than they do now. Slower growth makes it harder to recover from recurring insults like bleaching.