Extensive bleaching of the Great Barrier Reef has now occurred for the second year in a row, prompting fears that much of the coral has “zero prospect” of ever recovering.
Not only that but our window to save the remainder of the World Heritage Site is “rapidly closing” say experts.
The annual aerial survey of the Reef, from the ARC Centre of Excellence for Coral Reef Studies, has confirmed scientist’s worst fears that approximately 1500km (900 miles) of additional coral have been bleached in just one year.
In 2016, a study revealed that 80-100% of the northern section was dead as a result of coral bleaching. That has now extended to the middle corridor, leaving only the southern third “unscathed”, according to Professor Terry Hughes.
Although bleaching doesn’t necessarily mean dead coral, this back-to-back devastation is unprecedented in the history of the reef, which has only seen four bleachings ever, in 1998, 2002, 2016 and now 2017.
It is particularly important because it takes at least a decade for even the fastest growing corals to recover, so mass bleaching events set only twelve months apart like this offer zero prospect of recovery for reef that was damaged in 2016.
The team blamed the bleaching on record-breaking temperatures, driven by global warming. And said that even without the assistance of El Niño conditions weather conditions, climate change is causing these problems.
Not only that but tropical cyclone Debbie struck the Great Barrier Reef at the end of March with a spread of damage up to 100km in width.
Professor Hughes said: “Clearly the reef is struggling with multiple impacts.
“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.”
Coral bleaching takes part in three stages, and leaves the coral without protective algae tissue, causing it to die. This happens in cases of extreme environmental stress.