Published: Thu, May 31, 2018
Sci-tech | By Brandy Patterson

'Death event' threatens Great Barrier Reef

Although the study shows that the Great Barrier Reef can show great resilience, Webster says it would be very hard for the reef to survive its current stressors, especially since the rise in the sea's surface temperature is occurring much faster than ever.

The research team found that the reef survived all those calamities by moving laterally by up to 4.9 feet every year.

The researchers summarized the new study writing, "Here we document the evolution of the Great Barrier Reef (GBR), the world's largest reef system, to major, abrupt environmental changes over the past 30 thousand years based on comprehensive sedimentological, biological and geochronological records from fossil reef cores".

It is a concern that environmentalists have been raising in recent years, as increased quantities of sediment, largely from grazing lands and due to deforestation, are entering the Reef affecting the water quality and reducing sunlight available to corals.

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The warming water temperature kills off the algae that nourish the coral and provide the vivid colors of the reef.

A landmark global study of the Great Barrier Reef has shown that in the past 30,000 years the world's largest reef system has suffered five death events, largely driven by changes in sea level and associated environmental change.

The study, published in the journal Nature Geoscience, shows both glaciation and deglaciation events had a significant impact on the reef.

A new study by a group of global researchers looked at fossil reef cores at 16 sites across North Queensland in Australia.

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As sea levels dropped in the millennia before that time, there were two widespread death events (at about 30,000 years and 22,000 years ago) caused by exposure of the reef to air, known as subaerial exposure.

Previous studies have established a past sea surface temperature rise of a couple of degrees over a timescale of 10,000 years, but current forecasts change are around 0.7 degrees in a century, Webster said. It survived that event, but it took many thousands of years for it to grow back to normal again. However, the rapid increases in temperature and sea-level due to current changes in climate may be too much for the reef to properly adapt as it has before. While today's sea level rise is only about 10% the rate about 13,000 years ago, it is expected to rise rapidly in the coming years, notes the report.

"I have grave concerns about the ability of the reef in its current form to survive the pace of change caused by the many current stresses and those projected into the near future", says Jody Webster, lead researcher on the project.

And while this suggests the reef may be more resilient than once thought, it has likely never faced an onslaught quite as severe as today, they added.

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