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

Published: 1:40pm, 14 Oct 2020Updated: 12:49pm, 15 Oct 2020

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.

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.