Two-thirds of Great Barrier Reef may be damaged beyond recovery

Two-thirds of Australia's Great Barrier Reef have been severely damaged by coral bleaching as a result of warming seas, in an event scientists say it will be hard to recover from.

Coral bleaching occurs when algae living within the coral tissue are expelled, usually as a result of water temperatures being too high. As a result, the coral loses its vibrant appearance and turns white. Still alive, but weakened, coral can recover from such an event if cooling occurs soon enough for algae to embed again.

However, this latest announcement from James Cook University in Australia – which recorded and studied aerial footage of the entire reef in 2016 and 2017, matching 800 individual coral reefs in both surveys – warns that the coral may struggle to recover because current damage is the result of two severe bouts of bleaching occurring in the space of just 12 months. Historically, such severe damage (in this case, impacting 1,500km of reef), has occurred years apart.

“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, director of the ARC Centre of Excellence for Coral Reef Studies at James Cook University who headed up the aerial surveys, said in a university 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.”

Tropical Cyclone Debbie also hit the reef last month, damaging an area 100km-wide that had been largely undamaged until that time. Despite this, Hughes is adamant that global warming is the main culprit threatening the natural wonder’s survival. He said: “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.”

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