At a Glance

The deaths have occurred over the last 30,000 years and were triggered by changes in the ecosystem's environment.Scientists fear the reef will not likely survive the current rates of temperatures rising on the surface of the sea,

The Great Barrier Reef has “died” at least five times over the last 30,000 years as it worked to keep up with sudden environmental changes, according to a recent study.

An international team of researchers suggests the largest living thing on Earth has had to , which forced the reef to move around to survive.

Two widespread , according to the study. Both involved subaerial exposure, meaning the reef was exposed to air. In that time, the reef shifted toward the sea to try to keep up with the falling sea levels.

The Last Glacial Maximum saw two more reef deaths around 17,000 to 13,000 years ago due to a sudden rise in sea level, which caused the reef to migrate toward land in an effort to keep up. The last death event struck roughly 10,000 years agoand appears to have been triggered by massive amounts of sediment around the reef and the resulting poor water quality, in addition to the general sea level rise.

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“Our study shows the reef has been able to bounce back from past death events during the last glaciation and deglaciation,” lead author and Sydney University School of Geosciences associate professor Jody Webster said in the release. “However, we found it is also highly sensitive to increased sediment input, which is of concern given current land-use practices.”

The researchers used data from fossil reef cores collected from 16 sites around Mackay and Cairns and looks at the timeframe right before the “Last Glacial Maximum” occurred roughly 20,000 years ago. At that time, sea levels were more than 380 feet below where they are today.

According to the scientists, the reef has likely been able to adapt over time thanks to the habits of its corals and coralline-algae, as well as the ecosystem’s ability to move laterally between roughly 2 and 5 feet annually.

Despite the ecosystem's ability to migrate, Webster says the pace at which it moves is likely not enough to help it survive the current rates of temperatures rising on the surface of the sea, steep drops in coral coverage and repeated coral bleaching events, and an increase in sediment.

“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,” said Webster.

“Our study shows that as well as responding to sea-level changes, the reef has been particularly sensitive to sediment fluxes in the past and that means, in the current period, we need to understand how practices from primary industry are affecting sediment input and water quality on the reef,” he added.

“If you can , over longer time-scales you can help it re-establish as it has done in the past," ARC Centre of Excellence for Coral Reef Studies research fellow Tom Bridge, who was not involved with the study, told The Sydney Morning Herald. "We need to make sure the conditions are there [for the reef] to recover."