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    The Great Barrier Reef Nearly Died Once Before. But It Bounced Back

    The Reef's recovery 125,000 years ago offers hope that the ecosystem could flourish again, scientists say.

    The Great Barrier Reef is under threat from coral bleaching, but a new study shows the 2,300km-long ecosystem almost died out once before – and made a full recovery.

    Scientists analysed core samples from an ancient reef during a period of great environmental instability for the study, published this month in the peer-review journal Global and Planetary Change.

    It was characterised by melting ice sheets and a rapid sea-level rise.

    “This stage of the reef appears to have come close to drowning and therefore almost died due to major environmental changes,” said study supervisor Jody Webster, an Associate Professor at the University of Sydney.

    But then the sea-level rise stabilised during this time more than 125,000 years ago, known as the Last Interglacial period. And shallow reef growth restarted.

    This is significant because while sea levels were higher then than they are now, the climate change threats are similar to those the Earth faces today, according to the study’s lead author, Dr Belinda Dechnik from the Geocoastal Research Group in the School of Geosciences.

    “The findings highlight the importance of increasing the reef’s resilience now,” she said.

    The collaborative project with the University of Queensland and Queensland University of Technology and other institutions from the United States, Spain also accurately identified of the age of the fossil reef that grew before the modern Great Barrier Reef – some 129,000-121,000 years ago.

    “The Great Barrier Reef is like a sponge cake – the modern reef is just the last layer,” said Dr Dechnik, who undertook the research as part of her PhD.