The Great Barrier Reef is once again experiencing a dramatic bleaching event and scientists believe that several regions might be damaged beyond any help as they were yet to recover from the 2016 bleaching event.
Last year's event damaged 95 percent of the northernmost third of the reef, while the current one has been particularly devastating for the middle third of the reef. An aerial survey of the reef, conducted by the ARC Centre of Excellence for Coral Reef Studies, covered 8,000 kilometers (5,000 miles), a similar area to the 2016’s survey.
“The combined impact of this back-to-back bleaching stretches for 1,500 km (900 miles), leaving only the southern third unscathed,” Professor Terry Hughes, the director of the Centre, who undertook the surveys in both 2016 and 2017, said in a statement.
The bleaching is caused by the increase in temperature of the water due to global warming. The amazing colors of corals are due to the algae that inhabit their tissue, with which they have a symbiotic relationship. The algae provide nutrients for the corals, and the corals provide a safe haven for the algae.
Algae can’t survive when the water gets too hot, and global warming and a particularly strong El Niño pushed millions of corals beyond the point of no return last year. And while there’s no El Niño this year, the corals are still dying.
“This is the fourth time the Great Barrier Reef has bleached severely – in 1998, 2002, 2016, and now in 2017," explained Dr James Kerry, who also undertook the surveys. "Bleached corals are not necessarily dead corals, but in the severe central region we anticipate high levels of coral loss.”
“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,” he added.
Tropical Cyclone Debbie, which occurred around the end of March, has also been devastating to the reef. The storm was so intense that it damaged corals along a 100-kilometer (62 miles) path.
“Clearly the reef is struggling with multiple impacts,” added 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.”
The reef is not beyond saving but it requires decisive action from both the Australian government and the rest of the world against global warming.
3
