by As the early morning sun rises over the Great Barrier Reef, its light pierces the turquoise waters of a shallow lagoon, giving life to more than a dozen turtles.
These waters around Lady Elliot Island, off the east coast of Australia, provide some of the best snorkeling in the world – but they are also on the front line of the climate crisis, as one of the first places to suffer coral mass . a bleaching event that has now spread throughout the world.
The Great Barrier Reef has had its worst summer on record, and the US-based National Oceanic and Atmospheric Administration (NOAA) announced last month that the world is in the midst of a rare global coral bleaching event – the fourth one since the late 1990s – affecting at least 53 countries.
The corals are the casualties of soaring global temperatures that have broken historical records in the past year – mainly due to fossil fuels increasing carbon emissions and accelerated by the El Niño weather pattern, which increases ocean temperatures in this part of the world.
CNN spotted bleaching on the Great Barrier Reef in mid-February, on five different reefs that comprise the northern and southern parts of the 2,300 kilometer (1,400 mile) ecosystem.
“What’s happening now in our oceans is like underwater wildfires,” said Kate Quigley, chief research scientist at Australia’s Minderoo Foundation. “We will have so much heating that we will be going to the tipping point, and we will not be able to come back from that.”
Bleaching occurs when marine heat waves stress corals, causing them to expel algae from their tissues, draining their color. Corals can recover from bleaching if temperatures return to normal, but will be reduced if the water remains warmer than normal.
“It’s a death knell,” said Professor Ove Hoegh-Guldberg, a climate scientist at the University of Queensland in Australia and chief scientist at The Great Barrier Reef Foundation. “The temperatures got so hot, they’re off the charts … they’ve never happened before at this level.”
The destruction of marine ecosystems would provide an effective death sentence for around a quarter of all species that depend on reefs for survival – and threaten the billions of people who depend on reef fish for their food and their livelihoods. Reefs also provide vital protection to coastlines, reducing the impact of floods, cyclones and sea level rise.
“Humanity is being threatened at a rate that I’m not sure we really understand,” Hoegh-Guldberg said.
‘I pray the corals come back’
Taking off from Brisbane just after dawn, our tiny propeller plane skims miles of the Queensland coast before heading north out over the crystal-clear waters of the Coral Sea — revealing the beauty of this vast reef system beneath its surface .
Our destination is Mary Elliot Island, a remote coral cay perched on top of the southern tip of the Great Barrier Reef.
Pilot Peter Gash is the lessor of the island, and his family has been taking trips to the island for almost 20 years.
“We did our life’s work,” Gash said. “Me and my wife got married, I went and learned to fly planes so I could bring people here.”
Gash negotiates his small aircraft through bumpy crosswinds to land safely on the short, grass-covered runway.
Twenty years ago, the island was a barren landscape with no vegetation after years of mining the nutrient-rich waste of seabirds — known as guano — in the late 1800s.
The Gash family began to bring this island back to life, planting around 10,000 native species of trees to create a man-made forest and nature reserve, and using solar power, batteries and a water desalination system to support a small resort ecotourism.
There are now up to 200,000 seabirds on the island, which has helped regenerate the coral reefs on the island’s edge.
“If we can recover this little place, this little circle, we can recover this big place — the whole planet,” Gash said. “That’s what really motivates me, is trying to inspire people to know that it’s not hopeless, that it can be done.”
Gash takes CNN on a snorkel trip, diving down to explore the underwater rainforest in his backyard. The vibrant coral colonies burst with color and are home to hundreds of species including manta rays, reef sharks, clown fish and turtles.
When the island’s biggest enthusiast resurfaces to catch his breath, even he can’t hide his horror at the extent of the coral bleaching.
“It’s worse than I thought it would be,” Gash said, treading water on the surface. “I pray the corals come back next year.”
‘Quiet as a graveyard’
Beyond the Great Barrier Reef, the massive marine heat wave sweeping the globe is already affecting some of the world’s most famous coral reefs – including those in the Red Sea, Indonesia and the Seychelles.
Last year, the dramatic rise in ocean temperatures caused widespread coral destruction in the Caribbean and Florida – and US experts are predicting more damage there next summer.
“I’m increasingly concerned about the summer of 2024 for the Caribbean and Florida more broadly,” said Derek Manzello, coordinator of NOAA’s Coral Reef Watch program.
“It won’t take much additional seasonal warming to push temperatures over the bleaching threshold.”
In February, NOAA added three new levels to its coral bleaching alert maps, to enable scientists to assess the new scale of underwater warming.
Scientists hope the stark images of mass bleaching events – and the bleak predictions for longer-term coral reef survival – will push world leaders into aggressive action to lower carbon emissions by switching away from fossil fuels.
Researchers are also trying to buy some time for coral reefs until the world can bring emissions under control.
For the past six years, Peter Harrison and his team at Southern Cross University in New South Wales have been developing a “coral IVF” program to increase coral reproduction on the reef. The researchers use fishing nets to capture healthy breeding coral spawn, then grow the larvae in swimming pools before releasing them to damaged areas of the reef to help encourage recovery.
“We need to act now to keep corals alive on as many reefs as possible around the planet,” said Harrison.
There are also research projects underway at the Australian Institute of Marine Science (AIMS) looking at breeding heat-resistant corals that can survive at higher temperatures, and developing AI tools to try and make some of the processes scalable for the sheer size of the reef.
The Australian government has faced criticism for pouring hundreds of millions of dollars into dozens of reef research projects, while doubling down on the use and production of climate-changing fossil fuels – even allowing the opening of four new coal mines. in 2023.
“We have this terrible disagreement that Australia is mining, selling to burn on a large scale, and at a great pace the very thing, the pollution that is driving the destruction of this beautiful place,” said David Ritter, CEO Greenpeace Australia. CNN on top of a boat deck near Briggs Reef, in the northern Great Barrier Reef.
Australia has committed to sourcing 82% of its electricity from renewable sources by 2030 and has legislated a path to net zero emissions by 2050. But the pace of that transition is too slow for many activists, who point out that it is years the planet is still warming. come from carbon pollution that has already been released into the atmosphere.
“The truth is that more disasters are overcharged by climate change baked into the system,” said Ritter.
Scientists predict that at the current rate of warming, global average temperatures could be 2 degrees Celsius above pre-industrial levels by 2050. At that level of heat, 99% of coral reefs will simply die.
For the marine biologists who are witnessing this death, there is real sadness.
Everyone involved in the reef is “wrestling” with feelings of grief and helplessness, said David Wachenfeld, AIMS research program director.
“Coral reefs are at least canaries for climate change in the mine,” he said. “The trajectory we’re on now is pretty scary.”
Harrison, the researcher at Southern Cross University, described it as “ecological grief.”
“If you swam past a reef system that was vibrant, colorful a few months earlier – the sounds of the reef were incredible,” he said.
“And you swim back to it, and the whole thing is like a graveyard. It’s as quiet as a graveyard.”
The documentary “World Warning: Australia’s Climate Disasters” will air on Anderson Cooper’s The Whole Story this Sunday, May 5, at 8 pm ET.
For more CNN news and newsletters create an account at CNN.com
