The coral of the Great Barrier Reef is experiencing “widespread” bleaching just two years after the reef’s last mass bleaching event in 2020.
The Great Barrier Reef Marine Park Authority said Friday it had observed the bleaching after conducting surveillance flights over the 1,243-mile reef, as AFP reported.
“Bleaching has been detected across the Marine Park — it is widespread but variable, across multiple regions, ranging in impact from minor to severe,” the authority said in an update. “Most observations of bleaching have been of paling or fluorescing but several locations have whole colonies bleached white.”
The reef had been experiencing a heat wave during February and early March, the authority said. Temperatures began to cool this week, but sea surface temperatures are still above average, ranging from 0.5−2 degrees Celsius above average across the park. In the Far North and in inshore areas between Townsville and Rockhampton, temperatures are as much as two to four degrees Celsius above average. They are expected to stay around one degree Celsius above average through the end of the month.
“Most of the Marine Park has accumulated significant heat stress over the summer, with the central Reef experiencing the highest heat stress accumulation,” the authority said.
Coral bleaching occurs when high water temperatures force the coral to expel the algae that give them food and color. Mass bleaching events have become more frequent because of the climate crisis, and the reef has experienced five in a little more than two decades.
Professor Terry Hughes, a coral expert from James Cook University, told The Guardian on Wednesday that he thought the reef was in the midst of a sixth mass bleaching event.
“We all breathed a sigh of relief because corals that were pale in December regained their colour in January and February. But in the last three weeks there have been reports of moderate to strong bleaching all along the reef,” he said.
However, Great Barrier Reef Marine Park chief scientist Dr. David Wachenfeld told Guardian Australia that it was too soon to tell if this bleaching represented a mass event.
“There is certainly a risk we are seeing a mass bleaching event, but we aren’t in a position to confirm that yet,” he said. “We want to finish the aerial surveys to really understand this before we make a call on the extent and severity of this bleaching.”
One concerning element of the current bleaching is that it is occurring during a La Niña weather event, which usually brings cooler temperatures to the Pacific Ocean, AP News reported.
“This is a sure sign that climate change caused by burning coal, oil and gas is threatening the very existence of our reef,” Greenpeace Australia Pacific climate impacts campaigner Martin Zavan said in a statement reported by AP News.
The bleaching comes days before the UN is expected to start a 10-day investigation of the reef’s health on Monday, The Guardian reported. The investigation is supposed to help determine whether the reef’s United Nations Educational, Scientific, and Cultural Organization (UNESCO) World Heritage site status should be listed as “in danger” because of climate change, AP News explained. The Australian government, which supports the burning of fossil fuels, managed to stave off such a status change last summer, but the World Heritage Committee will consider the question again in June.
To protect the reef, environmental advocates called on the Australian government to reduce fossil-fuel emissions.
“Reducing Australia’s domestic and exported emissions fast, this decade, is the main solution within our control,” WWF Australia head of oceans Richard Leck said, as The Guardian reported.