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Australia’s Great Barrier Reef has lost half its corals in past 25 years due to climate change

  • Scientists expect the corals to continue dying off unless Paris Agreement commitments to stem the increase in global temperatures are kept
  • The reef, worth US$4 billion a year in tourism revenue for Australia before the coronavirus pandemic, is in danger of losing its World Heritage status

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Changes in ocean temperatures stress healthy corals, causing them to expel algae living in their tissues which drains them of their vibrant colours in a process known as bleaching. Photo: Handout
Half of the Great Barrier Reef’s corals have died over the past 25 years, scientists said on Wednesday, warning that climate change is irreversibly destroying the underwater ecosystem.
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A study published in the Proceedings of the Royal Society Journal found an alarming rate of decline across all sizes of corals since the mid-1990s on the vast reef off Australia’s northeast coast.

Larger species, such as branching and table-shaped corals, have been affected hardest – almost disappearing from the far northern reaches of the reef.

“They’re typically depleted by [up to] 80 or 90 per cent compared to 25 years ago,” said report co-author and James Cook University professor Terry Hughes. “They make the nooks and crannies that fish and other creatures depend on, so losing big three-dimensional corals changes the broader ecosystem.”

Aside from its inestimable natural, scientific and environmental value, the 2,300km (1,400 mile) reef was worth an estimated US$4 billion a year in tourism revenue for the Australian economy before the coronavirus pandemic.

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