This photo from 7 March 2022 shows coral bleaching on the Great Barrier Reef, off the coast of the Australian state of Queensland. Australia’s Great Barrier Reef experienced its sixth massive bleaching event in 2022 as climate change has warmed the ocean, raising concerns over whether one of the world’s natural wonders is nearing a tipping point. Photo: Glenn Nicholls / AFP / Getty Images
This photo from 7 March 2022 shows coral bleaching on the Great Barrier Reef, off the coast of the Australian state of Queensland. Australia’s Great Barrier Reef experienced its sixth massive bleaching event in 2022 as climate change has warmed the ocean, raising concerns over whether one of the world’s natural wonders is nearing a tipping point. Photo: Glenn Nicholls / AFP / Getty Images

By Darryl Fears
26 March 2022

(The Washington Post) – Australia’s Great Barrier Reef is experiencing its sixth massive bleaching event as climate change has warmed the ocean, raising concerns over whether one of the world’s natural wonders is nearing a tipping point.

Reef managers confirmed Friday that aerial surveys detected catastrophic bleaching on 60 percent of the reef’s corals. The discovery is particularly disturbing, researchers said, because a cooling La Niña weather pattern in the ocean usually offsets warming that stresses coral and causes them to lose color.

“This is a first mass bleaching event during a La Niña,” said Emily Darling, a coral reef scientist who directs coral reef conservation for the Wildlife Conservation Society, in a phone interview. “It continues to reinforce that with extreme heat waves and water getting too hot, corals are losing their recovery windows — those times between bleaching events when we know corals can recover.”

The Reef Authority, together with our partners at the Australian Institute of Marine Science, have completed aerial surveys across a representative sample of 750 reefs on the Great Barrier Reef. Aerial surveys are a standard method which provide the best picture of the full spatial extent of bleaching severity at many reefs across a large, representative area of the Great Barrier Reef Marine Park. The bleaching observed from the air was largely consistent with the spatial distribution of the heat stress experienced. Coral bleaching has been observed at multiple reefs in all four management areas (the Far Northern, Cairns–Cooktown, Townsville–Whitsunday and Mackay–Capricorn), confirming a mass bleaching event, the fourth since 2016 and despite La Niña conditions. It is important to note that bleached coral is stressed but still alive. If conditions moderate, bleached corals can recover from this stress, as was the case in 2020 when there was very low coral mortality associated with a mass bleaching event. Weather patterns over the next couple of weeks continue to remain critical in determining the overall extent and severity of coral bleaching across the Marine Park. Video: Great Barrier Reef Marine Park

Unusually high ocean temperatures, up to 7 degrees Fahrenheit above normal, probably triggered the event. It is the sixth massive bleaching the reef has suffered in two decades, and the fourth since 2016. Back-to-back bleaching events in 2016 and 2017 affected two-thirds of the world’s largest reef.

“The pace at which bleaching events are now occurring on the Reef is a matter of huge concern,” Australia’s Great Barrier Reef Foundation said in a statement. “It clearly highlights the importance of transitioning rapidly to a low-carbon economy.

“It is too early to know the level of long-term damage that the bleaching has caused,” the foundation added, “because many corals will recover once thermal stress declines. However, based on what’s happened in the last five years, we would expect to see severe coral mortality in the shallowest regions of the worst affected reefs.” [more]

Climate warming has dealt yet another blow to the Great Barrier Reef