SYDNEY, Australia – Much of the Great Barrier Reef has been hit by a sixth mass bleaching event, the marine park authority said Friday, an alarming milestone for the coral wonder that points to the ongoing threat of climate change and greenhouse gas emissions.
Government scientists who last week surveyed 750 individual reefs spanning hundreds of miles using helicopters and small planes found severe bleaching in 60 percent of the corals.
Bleaching events have now occurred in four of the past seven years, with 2022 bringing an alarming first — a massive year-long bleaching of La Niña, when more rain and cooler temperatures would provide a moment of calm for sensitive corals to recover.
“We see that coral reefs cannot cope with the current warming and the frequency of climate change,” said Dr. Neal Cantin, a coral biologist who led one of the teams observing the reef’s condition. “We need to slow that warming down as quickly as possible.”
Coral bleaching is often referred to as a climate change warning system, a canary in the coal mine of a struggling Earth. It indicates that corals are under intense stress from the waters around them, which have been steadily getting warmer. Last year, scientists recorded the warmest year on record for the world’s oceans — for the sixth year in a row.
First, the stress on coral reefs appears in bright, almost neon colors, as coral, being an animal, expels the algae that live in it and provides the coral with food. The corals turn white as bone, but can still recover if the temperature cools long enough.
However, scientists report that this has become increasingly rare. Between 2009 and 2019, a sweeping study from last year found that 14 percent of the world’s coal reefs were lost.
Along the 1,500 miles of the Great Barrier Reef—a beautiful ecosystem that can be seen from space—there are still large, healthy areas of coral, with sharks, turtles, rays, and crayon-colored fish.
But all along the natural wonder, there are also signs of damage. The blocks of underwater cemeteries, with gray fields of brittle, dead coral covered in wisps of unsightly algae, are growing with every massive bleaching event since the first occurred in 1998.
In Australia, this decline has become increasingly politicized. The government of Prime Minister Scott Morrison, which has done little to reduce the country’s dependence on fossil fuels or its exports, has repeatedly urged the United Nations to defy its own scientific advice and avoid listing the reef as endangered. world heritage sites.
Rather than aggressively pursuing emissions reductions, Australia has thrown hundreds of millions of dollars into long-term projects that aim to help the reef by cleaning up agricultural waste, killing invasive species or finding and breeding the most heat-resistant coral species.
Climate protests across the country have also intensified, some led by children, others by activists who have tried to block trains and traffic.
UN scientists are now in Australia to monitor the reef’s status. dr. Cantin said he met them on Friday afternoon and explained what the investigations had found.
The reef’s image (and Australia’s management of it) would be seriously tarnished if the United Nations suggests it is slowly on its way to extinction. But the damage to the world’s reefs goes far beyond a threat to tourism or a country’s reputation.
Although coral reefs cover a small portion of the ocean floor, together they support an estimated $2.7 trillion a year in goods and services worldwide, according to a recent report from the International Coral Reef Initiative. Their fish provide food for hundreds of millions of people around the world – and in Australia and elsewhere, they provide protection from the severe storms that are also increasingly common with climate change.
dr. Cantin said he was particularly disappointed with the spatial footprint of this year’s bleaching damage. Reefs closer to shore experienced the most extreme bleaching, but he said the bleaching appeared to cover a wider area than the successive outbreaks in 2016 and 2017.
He said it was the product of a summer that started early.
“In December we were already warmer than the historic summer maxima of February,” he said. There was a cooling off period in February, he added, but the last two weeks of this month saw little rain and continued heat.
“With the frequency of major stressful summers, we’ve been on watch for bleaching almost every year,” he said. “We are in troubling times.”
