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 World Heritage-listed reef off Australia’s northeastern 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 . . . They make the nooks and crannies that fish and other creatures depend on, so losing big three-dimensional corals changes the broader ecosystem,” report co-author and James Cook University professor Terry Hughes told AFP.
Aside from its inestimable natural, scientific and environmental value, the 2,300km-long reef was worth an estimated $4 billion a year in tourism revenue for the Australian economy before the pandemic.
The reef is at risk of losing its coveted world heritage status because of ocean warming – fuelled by climate change – damaging its health.
Changes in ocean temperatures stress healthy corals, causing them to expel algae living in their tissues – draining them of their vibrant colours in a process known as bleaching.