This ancient Australian reef is sending a silent distress call
Story by Hilary Whiteman, CNN
Photographs and video by Nush Freedman for CNN
Updated May 7, 2025
Editor’s Note: Call to Earth is a CNN editorial series committed to reporting on the environmental challenges facing our planet, together with the solutions. Rolex’s Perpetual Planet Initiative has partnered with CNN to drive awareness and education around key sustainability issues and to inspire positive action.
Halfway up the coast of Western Australia, American tourists Emily Wapman and Evan Risucci are riding a gentle current off Turquoise Bay, one of the country’s most remote and beautiful beaches.
It’s called drift snorkeling, and the water’s guiding them over Ningaloo, one of the world’s longest near-shore reefs, revealing coral that’s as white as the sand on the sea floor — drained of color by the stress of a severe and prolonged marine heatwave.
“You hear about it in school, there’s all this bleaching, but it’s very eye-opening to see the scale of it,” said Wapman, who’s just graduated with a degree in biological sciences and will soon start a master’s degree at UC Santa Barbara.
The Californians met in December on a dating app and are now touring Australia in an aging four-wheel drive they bought online and equipped for adventure.
Risucci, a filmmaker, admits he knows little about coral but is learning a lot from his travel companion. “I thought that the white coral was the live coral,” he said, squinting in the harsh Australian sun.
“It’d be good for tourists to know what’s actually happening,” he said. “Someone from the United States might come here and think, ‘wow, this is so pretty,’ and be completely oblivious to the fact that it’s all dead.”
Not dead, just sick
It’s not all dead, molecular ecologist Kate Quigley told CNN from a boat bobbing above Tantabiddi Sanctuary Zone, a popular destination for local tour boats within Ningaloo Marine Park off the West Australian coast. Ningaloo Reef is sick, like many coral reefs around the world.
Oceans are now storing 90% of the excess heat from global warming — and each of the last eight years has set a new record for the amount of heat stored in the ocean. As of this month, mass global bleaching that began in 2023 had spread to at least 82 countries and territories, impacting almost 84% of the world's reefs.
Ningaloo Reef had been spared from the mass bleaching event until this year when a marine heatwave collided with above average temperatures, then Western Australia’s hottest March on record.
In April, when CNN visited, brightly colored fish darted around a patchwork of healthy, dead and dying coral. The reef has bleached before, but for the first time, massive Porites — coral boulders, hundreds of years old — had begun ejecting healthy algae, draining them of color and opening the door for downy green algae to slowly spread over their ghostly frames — the marker of death.
“It was only a matter of time before bleaching would come here,” said Quigley, a principal research scientist with Minderoo Foundation, the philanthropic organization founded by Australian billionaire iron ore miner Andrew Forrest, who swam in these waters as a child.
Within the Minderoo Exmouth Research Lab, Quigley has been conducting experiments in selective breeding to try to create more heat-resistant baby corals in tanks that control temperatures to within 0.25 of a desired degree.
“Our ability to regulate temperature and environmental parameters within the labs here allows the replication of what climate change is doing to the reef and what climate change might do in the future,” said lab manager Zac Saber.
Coral was taken from warmer waters and bred with the same species from colder water to see which combinations produced the most heat-resilient offspring.
“What we found on the Ningaloo is that if you have a mom from a heat tolerant reef crossed or mixed with a dad from a less heat tolerant reef, you can get two times as much heat tolerance in your baby corals,” said Quigley. “The baby sometimes is more heat tolerant even than the mom.”
In March, for the first time ever, World Heritage-listed reefs on either side of Australia bleached in unison — Ningaloo in the west and the Great Barrier Reef in the east.
“When you get mass bleaching events on both reef systems, then you're really saying to every Australian, this is exactly what we were warned about, and it has now come true,” Forrest told CNN at an Indian Ocean Forum in Perth, jointly hosted by the Minderoo Foundation and France ahead of the United Nations Ocean Conference (UNOC) in Nice in June.
Having made his fortune from iron ore, Forrest is trying to convince the mining industry and its investors to speed up the transition to renewable energy — a tough sell in Western Australia, a state rich in fossil fuels. Investing in clean energy to cut carbon emissions and contain temperatures is not only good for the environment — it makes business sense, said Forrest, who has a PhD in marine ecology. “If we destroy the oceans, we destroy our economy, and that's the principal message I'm really happy to get across.”
A magnet for holidaymakers
Every March and April, visitors flood to the small town of Exmouth, the gateway to Ningaloo Reef, to swim with whale sharks attracted by the annual coral spawning. Visitors at that time of year might also see humpback whales, manta rays and green turtles swimming on reefs teeming with marine life.
The wider region is a hotbed of fossil fuel extraction that’s generated immense profits and created emissions that are heating the oceans and killing the reefs.
As a signatory to the Paris Agreement, Australia was among the countries that agreed to try to contain global average temperature rise to below 1.5 degrees Celsius. Temperatures exceeded that in 2024, but the United Nations says the long-term goal remains achievable, if urgent action is taken to cut carbon emissions.
But new fossil fuel projects are still being proposed — including the Burrup Hub, a major gas venture north of Ningaloo Reef that conservation groups say could be the biggest fossil fuel scheme ever developed in Australia. The re-elected Australian Labor government will soon decide on a key component of the plan — the North West Shelf extension — which would allow oil and gas company Woodside to extend operations at Karratha Gas Plant until 2070.
Bill Hare, CEO of non-profit international science and policy institute Climate Analytics, said it would be wrong for Labor to interpret its landslide win as a “full endorsement of their less than stellar performance on climate action.”
“Any compromise that they might think of to shorten this extension to 20 years or so would be widely seen as an extension of the performative climate action that they’ve undertaken the last three years in many ways, and an abdication of their responsibility to act,” he said.
“We all know, at least from the science point of view, that coral reefs probably won't survive much above one and a half degrees of global mean warming.”
Spawning on a dying reef
Back on Ningaloo Reef, the breeze is light enough for photographer Nush Freedman to delicately launch a drone high into the sky. From above Rangers Reef, the camera shows patches of faded coral. Below the surface, Freedman duck dives to get a closer shot. She moved to Exmouth 10 years ago and now documents the reef’s beauty — and its decline. “It's pretty heartbreaking to see these places that you love, and that you have a really personal connection to, change so much,” she said.
“This reef supports so many forms of life, different ecosystems, from the tiniest creatures all the way up to these huge marine megafauna that we have here,” she said. “The diversity of life is unlike anywhere else, and I think that what's magic about it — you never know what you're going to see.”
Baby corals bred in the lab haven’t been released on Ningaloo; not enough is known about the extent of the loss yet — that will only emerge during surveys in the next few months.
On the other side of the country, ongoing field trials on corals conceived at the National Sea Simulator, or SeaSim, in Queensland have shown that, so far, corals bred in a lab can survive on the Great Barrier Reef.
Selective breeding of corals from different parts of the reef also shows promising results, according to Patrick Laffy, senior research scientist with the Australian Institute of Marine Science (AIMS), and the co-author of a paper published last month.
“It looks like this kind of selective breeding can have a positive outcome for the juveniles and the larvae. But the caveat is that it's very species specific, and it's quite often reef specific as well,” Laffy said.
Scientists warn reef restoration projects are no substitute for climate action, and that restoring coral reefs already lost around the world would be prohibitively expensive using current techniques.
“There is increased pressure that we come up with some of these intervention strategies. And the timelines are getting rapidly shorter and shorter,” Laffy said.
Outside the lab, reefs only regenerate during mass spawning events over several nights once or twice a year, when the water fills with a slimy mix of eggs and sperm. Scientists had worried that the heat-damaged Ningaloo Reef wouldn’t spawn this year — but it did.
“I was absolutely relieved and thrilled because that means that, yes, the system is under pressure, the coral is sick, but there is still that ability to regenerate,” Quigley said.
“Spawning is all about the next generation. It's all about regeneration. It's all about babies going to new places and settling and building again, and so that, I think, should give people the sense that, yes, this is an ecosystem under threat, but we absolutely have not lost it yet, and we need to do more to protect it.”
