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Great Barrier Reef Has Died Five Times In Last 30,000 Years, Study Says (newsweek.com)
schwit1 quotes a report from Newsweek: You may well have heard that Australia's iconic Great Barrier Reef is dying as warmer and more acidic waters bleach the system's vibrant coral reefs. In fact, a heat wave killed nearly a third of the system's corals in 2016. Now, scientists writing in the journal Nature Geoscience have discovered the reef has bounced back from near-extinction five times in the last 30,000 years. The current stresses, however, are probably far more intense than those felt in the past.
Low sea levels 30,000 and 22,000 years ago killed coral by air exposure. The remaining reef shifted seaward and eventually bounced back. Rising sea levels -- like those we see today -- killed off the coral twice between 13,000 and 17,000 years ago. This time, coral inched close to land to survive. The reef system, the scientists think, migrated up to 60 inches a year in the face of a changing environment. The last of the five great die-offs occurred about 10,000 years ago, and was likely caused by a huge influx of sediment, a reduction in water quality and a general sea level rise. The reef system may be due for another die-off sometime in the next few thousand years "if it follows its past geological pattern," study author Jody Webster told AFP. "But whether human-induced climate change will hasten that death remains to be seen."
Low sea levels 30,000 and 22,000 years ago killed coral by air exposure. The remaining reef shifted seaward and eventually bounced back. Rising sea levels -- like those we see today -- killed off the coral twice between 13,000 and 17,000 years ago. This time, coral inched close to land to survive. The reef system, the scientists think, migrated up to 60 inches a year in the face of a changing environment. The last of the five great die-offs occurred about 10,000 years ago, and was likely caused by a huge influx of sediment, a reduction in water quality and a general sea level rise. The reef system may be due for another die-off sometime in the next few thousand years "if it follows its past geological pattern," study author Jody Webster told AFP. "But whether human-induced climate change will hasten that death remains to be seen."
We show that reefs migrated seaward as sea level fell to its lowest level during the most recent glaciation (~20.5–20.7 thousand years ago (ka)), then landward as the shelf flooded and ocean temperatures increased during the subsequent deglacial period (~20–10ka).
They didn't just look at where the reef is now, but where it has been in the past. It has an ability to migrate at 0.2-1.5m/year. The reef is older, but it wasn't always in the same place. Source
So what you are saying is that your lead sentence is false, the reef is more than the dead skeletons of corals, given that part of it is alive. Further, although you do not acknowledge it or perhaps even know it, it is also an entire eco-system consisting of more than just corals - in fact they are the most diverse ecosystems in the entire ocean.
The notion that "dead corals will bounce back within a year or two" is similar to asserting - "Hey, trees sprout from seeds every spring! So if an old-growth forest is destroyed, it can bounce back the very next year!"
Big, big different between the earliest stages of recolonization and a mature ecosystem.
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