Great Barrier Reef faces catastrophic back-to-back bleaching

Two-thirds of the Great Barrier Reef is experiencing severe coral bleaching for the second time in just 12 months. Global warming is to blame.

The news for the Great Barrier Reef couldn’t be worse. For the second time in just 12 months scientists have recorded severe coral bleaching across huge tracts of the Great Barrier Reef. In 2016, bleaching was most severe in the northern third of the reef, while this year the middle third is experiencing the most intense bleaching.

“The combined impact of this back-to-back bleaching stretches for 1,500 km, leaving only the southern third unscathed,” Professor Terry Hughes of the ARC Centre of Excellence for Coral Reef Studies said in a statement.

“The bleaching is caused by record-breaking temperatures driven by global warming. This year, 2017, we are seeing mass bleaching, even without the assistance of El Niño conditions.”

This is the fourth time that the Great Barrier Reef has bleached severely: 1998, 2002, 2016 and now 2017. While bleached corals are not necessarily dead corals, the scientists predict there will be high levels of coral loss in the central region.

“It takes at least a decade for a full recovery of even the fastest growing corals, so mass bleaching events 12 months apart offers zero prospect of recovery for reefs that were damaged in 2016,” said his colleague Dr James Kerry.

This year the Great Barrier Reef was also struck by the tropical cyclone Debbie at the end of March, which caused varying levels of damage along a path of up to 100 kilometres in width.

“Clearly the reef is struggling with multiple impacts,” said Hughes. “Without a doubt the most pressing of these is global warming. As temperatures continue to rise the corals will experience more and more of these events: 1°C of warming so far has already caused four events in the past 19 years.”

“Ultimately, we need to cut carbon emissions, and the window to do so is rapidly closing.”


Image credit: Greg Torda

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