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Scientists worry about Australia's Great Barrier Reef, and no wonder. Like many coral reefs, the largest in the world will be attacked by water pollution, overfishing and warmer seawater caused, among other things, by climate change.
But a large new study over a decade shows that the reef was capable of being thrown back by a series of "deaths" in the last 30,000 years. This suggests that the reef could be more resistant to changes in sea level and temperature than before ̵
"We have discovered that the Great Barrier Reef has experienced cycles of reef death and growth in large areas in response to changes in sea level and water quality," said Helen V. McGregor, geologist and climate change researcher at Wollongong University in Australia and member of the international team of scientists who conducted the study, told NBC News MACH
New hope for the reef?
What does this finding mean for the long-term survival prospects of the Great Barrier Reef?
"Our research tells us that the reef evolves in response to major changes in the region's climate and environment, but there are limits," McGregor said. "Exceeds the limits and the reef does not survive, the reef can regenerate as conditions improve, but there's a catch – the reef needs time to come back."
McGregor predicted that the reef would "become a shadow of his former self" unless steps were taken to curb climate change and other threats, but said that "our research gives me hope that the reef will recover can. "
Others sounded a more cautious note.
I have great concerns about the ability of the reef in its present form to survive the speed of change caused by the many current and projected tensions in the near future, "said Jody M. Webster, geoscientist at the University of Sydney and Head of the scientific team said in a written statement.
Webster said that whether the reef was resilient enough to survive in the long run was an open question.
For the study published in the journal Nature Geoscience on May 28, scientists used a variety of techniques to analyze fossilized reef sample cores at 16 locations in Cairns and Mackay on the Australian northeast coast There have been 5 crashes of large parts of the reef over the last 30 millennia.
One death occurred 30,000 years ago, when the sea level exposed the reef to the air and a similar event lasted 22,000 years ago. At that time, the reef survived by shifting its position seaward and finding deeper water there.
Two more deaths occurred before 17,000 and 13,000 years ago, when swiftly rising seas flooded the reef and drowned its coral. At that time, the reef moved landward.
The last death occurred 10,000 years ago, when the reef was hit by large amounts of sediment known to damage coral by blocking and possibly burying the sunlight.
Saving Coral Reefs
From transplanting healthy corals to damaged reefs, cultivating stubborn corals, and protecting reefs with chemical sunscreens, scientists are exploring a range of ways to ensure the survival of coral reefs in the world.
But McGregor said the key Keeping reefs is easy. "It's tempting to seek new strategies to protect the Great Barrier Reef, but frankly, we already know what to do: maintain good water quality and [carbon] reduce emissions to limit the rise in ocean temperature," she said in her email  Whether the new study provides a degree of security for those who care for the reefs of the world was provided by Stuart Sandlin, a marine ecologist at the Scripps Institution of Oceanography, who is not on the new research was involved, its own rating.  "You'll find coral reef professionals standing on one side of the fence or optimism or pessimism on the other," he told MACH in an e-mail. "However, this study reminds us not to forget that while we see many examples of coral reef dying, there are phenomenal examples of coral reef growth from which we can derive hope, or at least perspective."
Coral reefs are valuable for many reasons. Not only do they provide a habitat for marine organisms and protect coastal areas from storms and waves, they are often crucial for tourism and commercial fishing.
The Great Barrier Reef stretches over more than 1250 miles along the northeastern coast of Australia and covers an area of approximately 135,000 square miles. It houses more than 1,500 species of fish, 30 species of whales, dolphins and porpoises, as well as many species of sea turtles, birds and snakes. It was declared a World Heritage Site in 1981.
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