The Great Barrier Reef has lost half its corals within 3 decades

[hatrack]

1. From WP Coverage Of Same Story: "I Know The Reef Is Dead. It Just Doesn't Know It Yet."

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“The decline occurred in both shallow and deeper water, and across virtually all species — but especially in branching and table-shaped corals,” Terry Hughes, a professor at the ARC Center of Excellence for Coral Reef Studies in Queensland and a co-author of the research paper, said in a statement Tuesday. “These were the worst affected by record breaking temperatures that triggered mass bleaching in 2016 and 2017.”

On some areas of the northern half of the reef, “the abundance of large colonies on the crest dropped” by up to 98 percent, according to the study, published in the journal Proceedings of the Royal Society B. By contrast, there was a slight increase on the southern slope, about 25 percent. It’s a clear sign of rapid decline.

“We expect this decline to continue” because of warming caused by humans, Hughes said. “The only effective way to improve the outcome for coral reefs is global action on greenhouse gasses. If global temperatures rise to 3 or 4 [degrees Celsius], the reef will be unrecognizable, so there is no time to lose.” “We have evidence from some parts of the reef that recruitment rates are only recovering very slowly … and are nowhere near levels prior to the bleaching events,” Andreas Dietzel, another professor at the ARC Center and a co-author of the paper, said in an email.

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Bob Richmond, a research professor and director of the Kewalo Marine Laboratory at the University of Hawaii at Manoa, called the study “a really excellent piece of work,” with the most comprehensive research on Great Barrier Reef coral populations that he’s seen. “What they’re showing is these demographic changes are occurring on a regional scale … on reef slopes that make it difficult for coral reefs to persist over time,” Richmond said. In his long experience of visiting and researching reefs around the world, “if I don’t see one-year-old, two-year-old, three-year-old corals, I know that reef is dead. It just doesn’t know it yet.”

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https://www.washingtonpost.com/climate-environment/2020/10/13/warming-has-killed-half-coral-great-barrier-reef-study-finds-it-might-never-recover/