Australia's Great Barrier Reef is suffering a second straight year of mass coral bleaching 鈥� something never seen before, marine scientists reported Monday.
Two-thirds of the reef has been devastated by mass bleaching this year, report researchers from the .
This is the fourth time the Great Barrier Reef has seen mass bleaching: 1998, 2002, 2016, and now in 2017, said James Kerry, who undertook this year and last year鈥檚 aerial surveys.
While bleached corals are not necessarily dead corals, he says his team anticipates high levels of coral loss. He notes that it takes at least a decade for a full recovery of even the fastest growing corals, so reefs that were damaged in 2016 have virtually no chance of recovery.
鈥淭he 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.鈥�
When surrounded by warmer-than-normal waters, corals expel tiny photosynthetic algae, draining them of their colour. The corals can recover if the water temperature drops again and the algae are able to recolonize them. But recovery is a slow, multi-year process.
Just last month, the Australian government's noticing a second straight year of mass coral bleaching, after it conducted its own aerial survey.
The ARC Centre鈥檚 director, Terry Hughes, says what鈥檚 needed now is quick action to slow climate change.
鈥淯ltimately, we need to cut carbon emissions, and the window to do so is rapidly closing,鈥� he said in a statement.
