Great Barrier Reef: 91% of reefs studied suffered from coral bleaching in 2022



CNN

Warming waters due to escalating climate change have caused coral bleaching on 91% of reefs surveyed along the Great Barrier Reef this year, according to new findings from an Australian government agency.

Scientists from the Great Barrier Reef Marine Park Authority (GBRMPA) confirmed in March that this was the sixth mass bleaching event on record for the reef and the fourth since 2016.

But Tuesday’s report, Reef snapshot: summer 2021-22, found nearly all coral reefs examined in the 1,400-mile (2,300-kilometer) system were affected by bleaching.

Coral reefs are some of the most vibrant marine ecosystems on earth: between a quarter and a third of all marine species depend on them at some point in their life cycle. But the rapid warming of the planet due to human emissions of heat-trapping gases is causing above-average water temperatures, leading to stress events like mass bleaching.

Coral bleaching tends to occur when the water temperature is much warmer than normal. But for the first time, this massive bleaching is occurring despite La Niña, a weather event characterized by cooler-than-normal temperatures in the equatorial Pacific Ocean, the Authority’s scientists said.

The report surveyed a total of 719 reefs from a low-flying aircraft during the 2021-2022 Australian summer season and found that 654 reefs, 91%, “showed some bleaching.”

“Surveys confirm a massive bleaching event, with coral bleaching observed on multiple reefs in all regions. This is the fourth mass bleaching event since 2016 and the sixth to occur on the Great Barrier Reef since 1998,” the Australian government’s Great Barrier Reef Marine Park Authority said in its findings.

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The waters of the Great Barrier Reef began to warm up in December 2021 and exceeded “record summer highs”. It was hit by three separate heat waves during the summer through early April 2022, which increased “heat stress” in the central and northern areas of the reef, according to the report.

The stressed coral expels algae from its tissue, depriving it of a food source. If conditions don’t improve, the coral can starve and turn white as its carbonate skeleton is exposed.

“Even the most robust corals require almost a decade to recover,” Jodie Rummer, an associate professor of marine biology at James Cook University in Townsville, told CNN in March.

“So we’re really missing that window of recovery. We’re having back-to-back bleaching events, back-to-back heat waves. And the corals are just not adapting to these new conditions,” she said.

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The report warned that the climate crisis remains the biggest threat to the reef and that “reef-disturbing events are becoming more frequent.”

It is the fourth mass bleaching in six years and the first since 2020, when about a quarter of the studied reef showed signs of severe bleaching. That event came just three years after back-to-back bleaching events in 2016 and 2017. The previous bleaching occurred in 1998 and 2002.

Scientists say time is running out for reefs to recover and governments must urgently address the root cause: the climate crisis.

This photograph taken on March 7 shows the current state of coral in the Great Barrier Reef, off the coast of the Australian state of Queensland.

“To give our reef a fighting chance, we must tackle problem number one: climate change. No amount of funding will stop these bleaching events unless we reduce our emissions this decade,” Amanda McKenzie, executive director of the Climate Council, said in March.

The Great Barrier Reef is one of Australia’s national treasures, stretching some 1,400 miles (2,300 km) off the Queensland coast and drawing some three million tourists a year before the pandemic.

The Australian government has faced prolonged pressure from UNESCO to show it is doing enough to save the reef and has been criticized by global climate experts, among others, for not doing enough to steer Australia away from the fossil fuels and reduce greenhouse gas emissions.

The report’s release comes after leading scientists called on the agency to release its findings ahead of the May 21 federal election.

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