The ARC Centre of Excellence for Coral Reef Studies, based in Northern Queensland, released the report to help bring awareness to the back-to-back bleaching which stretches for more than 1,500 km.
— CoralCoE (@CoralCoE) April 10, 2017
Professor Terry Hughes, Director of the ARC, undertook aerial surveys in both 2016 and 2017, covering more than 8,000 km of the eastern coastline of Australia.
“The combined impact of this back-to-back bleaching stretches for more than 1,500 km, leaving only the southern third unscathed,” he said.
“The bleaching is caused by record-breaking temperatures driven largely by global warming.”
What is coral bleaching?
Coral bleaching is the process in which coral turns completely white.
Factors such as warmer water temperatures and global warming, run-off and pollution, over-exposure to sunlight, and extremely low tides, can tend to stress the coral. The coral then expels an algae (zooxanthellae) living in the tissues.
Coral and algae depend on each other to survive, so when the algae is expelled from the coral, it turns white.
Dr James Kerry from the ARC said that despite the severe bleaching of the Great Barrier Reef in 1998, 2002, 2016 and now 2017, the bleached corals are “not necessarily dead”.
“It would take at least a decade for a full recovery of even the fastest growing corals, so while there is a slim chance of recovery, the chances are exactly that, very slim,” he said.
The reef is still alive, say tour operators
Despite the grim conditions, residents in far north Queensland have been called upon to spread the message that the Great Barrier Reef is not totally dead.
Col McKenzie, Executive Director of the Association of Marine Park Tourism Operators (AMPTO), told News Corp Australia it was important for locals to inform tourists exactly what the real effects of bleaching were.
“People are equating bleaching with death,” he said.
“Well, it doesn’t quite work that way.
“The last two years, there have been dramatic amounts of heat stress and we’ve seen significant mortality in the Far North.
“We haven’t seen the same mortality rate between Cairns and Townsville.”
What parts of the reef are still worth seeing?
As the maps below show, many parts of the reef around the Whitsunday Islands and Mackay have remained largely unaffected by bleaching over 2016 and 2017.
In the ‘South’ region around Mackay, only 1% of the reef shows bleaching. But in the ‘North’ region above Cairns, 67% of the Great Barrier Reef has been bleached.
— CECHR (@CECHR_UoD) November 29, 2016
What’s hurting the reef?
According to Professor Hughes, the recent impact of Tropical Cyclone Debbie has not helped the reef, leaving a path of damage almost 100 km in width.
“Clearly the reef is struggling with multiple impacts,” he explains.
“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.”