A core-sampling study has unveiled a deep history of wild weather on the Great Barrier Reef. 

The study by the University of Queensland allowed researchers to understand for the first time what water quality was like on the Reef over a period of 8,000 years.

Reef cores were recovered from Heron and One Tree reefs by UQ’s Dorothy Hill Research Vessel, before Professor Jianxin Zhao dated and analysed the cores at UQ’s Radiogenic Isotope Facility.

The analysis focused on rare earth elements preserved in microbialites – rocks made by microbes – that have been growing throughout the Great Barrier Reef’s history.

“Eight thousand years ago, extreme runoff from an intense Indian-Australian summer monsoon affected water quality in the southern offshore Reef,” says report co-author Dr Salas-Saavedra.

“Water in the [Great Barrier Reef] was much dirtier, and poor water quality is known to be a major cause of reef decline around the world.

“But 1,000 years later, monsoonal rains eased and the water quality greatly improved.

“We noticed water quality declined during times of dampened El Niño Southern Oscillation frequency, which may have led to more La Niña-dominated wet climates in Queensland at those times – like the weather we have seen this year in Queensland.

“But as El Niño-dominated weather patterns became established, southern Great Barrier Reef water quality again improved to give us the beautiful Reef we know and love.”