Great Barrier Reef Hit By Severe Coral Bleaching For 2nd Year In A Row

For the first time in history, scientists have recorded back-to-back severe coral bleaching across huge tracts of the Great Barrier Reef.

Aerial surveys completed by the ARC Centre of Excellence for Coral Reef Studies show that bleaching was most severe in the middle third of the reef, while last year it was the top third. 

“The combined impact of this back-to-back bleaching stretches for 1,500 km (900 miles), leaving only the southern third unscathed,” says Prof. Terry Hughes, director of the centre, who undertook the aerial surveys in both 2016 and 2017.

“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.”

Credit: Greg Torda / Supplied.
It’s the fourth time in history the reef has bleached severely (also recorded in 1998 and 2002, as well as 2016 and 2017), with water quality expert Jon Brodie telling The Guardian it’s now in a “terminal stage”. Fuuuuuck.

Dr. James Kerry, who also undertook the aerial surveys in 2016 and 2017, says the back-to-back bleaching has basically given the coral affected last year a “zero prospect of recovery”.

“Bleached corals are not necessarily dead corals, but in the severe central region we anticipate high levels of coral loss,” he said.

“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.”

Credit: Bette Willis / Supplied.
In another blow to the reef’s health, Tropical Cyclone Debbie struck a corridor of the reef that had largely escaped the worst of the bleaching, yet has likely caused varying levels of damage.

“Clearly the reef is struggling with multiple impacts”, said Prof. 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.”

Photo: Ed Roberts / Supplied.