How Climate Change Caused the Great Barrier Reef's Latest Mass Coral Bleaching Event

Sophie Hirsh - Author

May 11 2022, Published 12:33 p.m. ET

Great Barrier Reef coral bleaching
Source: Getty Images

The Great Barrier Reef is one of the most beautiful natural wonders on our planet — but we are certainly not treating it that way. New data from the Australian government show that climate change has caused coral bleaching across most of the Great Barrier Reef. What is happening to the Great Barrier Reef, exactly?

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Keep reading for the details on the latest mass bleaching event in the Great Barrier Reef, which is the world’s longest coral system. It spans a length of 1,429 miles in the Coral Sea, off of Queensland, Australia’s coast.

What is happening to the Great Barrier Reef? The Great Barrier Reef Marine Park Authority just published a concerning report.

Great Barrier Reef
Source: Getty Images

On May 10, 2022, the Great Barrier Reef Marine Park Authority (GBRMPA) published a report titled “Reef Snapshot: Summer 2021-22” (bear in mind that Australia’s summers are during December, January, and February).

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The report found that “Above average water temperatures led to a mass coral bleaching event late in the summer.” Experts observed coral bleaching along the Reef across all three regions of the Reef, in varying degrees of severity. According to CNN, anthropogenic climate change has contributed to coral bleaching in 91 percent of surveyed reefs that make up the Great Barrier Reef.

The GBRMPA stated that this was the fourth bleaching event in the last seven years. Additionally, it was the first bleaching event during a La Niña year, which is concerning, as La Niña years should mean slightly colder temperatures.

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“The early indications are that the mortality won’t be very high,” said David Wachenfeld, chief scientist at GBRMPA, as per AP News. This is good news, considering that 2016 and 2017’s bleaching events caused “quite high levels of coral mortality,” according to the scientist.

“We are hoping that we will see most of the coral that is bleached recover and we will end up with an event rather more like 2020 when, yes, there was mass bleaching, but there was low mortality,” Wachenfeld stated.

What causes coral bleaching?

The GBRMPA noted that there are four central factors that cause coral bleaching. The most notable is above average sea temperatures — and as long as humans keep emitting greenhouse gases, ocean temperatures will only continue to rise, and coral bleaching will keep happening. According to the GBRMPA, the average maximum water temperature increasing by just 1 degree Celsius for about a month can cause severe bleaching.

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The second factor is cyclones and storms, which cause powerful waves that can damage coral reefs.

Third is flood plumes, which happen when rainfall causes muddy water to flow into the ocean, which can reduce water quality and therefore affect coral health.

And fourth is the coral predator crown-of-thorns starfish; when the starfish’s population grows beyond normal levels, they eat coral tissue at unsustainable rates.

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There are a number of programs working on monitoring and protecting the Great Barrier Reef, including one run by the Australian Institute of Marine Science, as well as the Long-term Monitoring Program, the Marine Monitoring Program, the Eye on the Reef Program, and the Reef Joint Field Management Program, as noted in the GBRMPA's report.

But these programs and organizations can only do so much to prevent coral bleaching — a far more effective approach would be to shut down the main source of this disaster: mass anthropogenic greenhouse gas emissions.

High-emission activities like burning fossil fuels, raising livestock, and deforestation directly contribute to the greenhouse gas effect, which raises sea temperatures, which causes coral bleaching, which hurts the many animals who rely on the Great Barrier Reef's coral system. If we do not take comprehensive climate action soon, the Great Barrier Reef is just one of many areas of planet Earth that will suffer.

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