Friday , December 3 2021

Heatwaves kill coral reefs far faster than thought: learning



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Sea waves are killing coral reefs far faster than previously thought, according to a new study released Friday.

Scientists knew that rising sea temperatures, blamed for global warming, could severely damage reefs through a "whitening" process, where high temperatures kill colored algae, covering and nourishing corals.

Repeated "whitening events", such as those that hit the Great Barrier Reef in Australia in 2016 and 2017, can eventually kill corals in a process that takes months or years.

If the sea temperature eases, the bleached corals are able to regenerate.

A new study finds that strong sea heat waves can actually impair the skeletal structure of corals, potentially killing organisms in days or weeks.

"The severity of these wave events is beyond the bleaching process. This is actually the moment when the coral animal itself dies," said Tracy Ainsworth, a co-author of the study at the University of New South Wales.

The study, which included researchers from Newcastle University in the UK, the Australian James Cook University, the Technical University of Sydney and the US National Oceanic and Atmospheric Administration, used CT scans of coral reefs to track the effects of extreme temperatures .

Scott Cook of James Cook University said that the rapid dissolution of coral skeletons after intense heat waves came as a surprise.

"Climatologists speak of 'unknown unknowns' – impacts we did not expect from existing knowledge and experience," he said. "This finding fits into this category. As we begin to understand this impact now, the question is how much more of these "unknown unknowns" can still be found that could bring faster and greater damage to coral reefs from climate change, "he said.

Coral bleaching in 2016-2017 affected up to half of corals in the 2,300 km (1,400 miles) reef, a UN World Heritage Site listed on the Australian East Coast.

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