In a hotter future, what comes after coral reefs die?
The fate of coral reefs has been written with a degree of certainty rare in climate science: at 1.5 degrees Celsius of global warming, most are expected to die.
This is not a far-off scenario. Scientists predict that the rise of 1.5 Celsius (2.7 Fahrenheit) will be reached within a decade and that beyond that point, many coral simply cannot survive.
It is important to accept this and ask what next "rather than trying to hold onto the past", said David Obura, chair of IPBES, the UN's expert scientific panel on biodiversity.
"I wish it were different," Obura, a Kenyan reef scientist and founding director of CORDIO East Africa, a marine research organisation, told AFP.
"We need to be pragmatic about it and ask those questions, and face up to what the likely future will be."
And yet, it is a subject few marine scientists care to dwell on.
"We are having a hard time imagining that all coral reefs really could die off," said Melanie McField, a Caribbean reef expert, who described a "sort of pre-traumatic stress syndrome" among her colleagues.
"But it is likely in the two-degree world we are rapidly accelerating to," McField, founding director of the Healthy Reefs for Healthy People Initiative, told AFP.
When stressed in hotter ocean waters, corals expel the microscopic algae that provides their characteristic colour and food source. Without respite, bleached corals slowly starve.
At 1.5C of warming relative to pre-industrial times, between 70 and 90 percent of coral reefs are expected to perish, according to the IPCC, the global authority on climate science.
At 2C, that number rises to 99 percent.
Even with warming as it stands today -- about 1.4C -- mass coral death is occurring, and many scientists believe the global collapse of tropical reefs may already be underway.
- What comes next -
Obura said it was not pessimistic to imagine a world without coral reefs, but an urgent question that scientists were "only just starting to grapple with".
"I see no reason to not be clear about where we are at this point in time," Obura said. "Let's be honest about that, and deal with the consequences."
Rather than disappear completely, coral reefs as they exist today will likely evolve into something very different, marine scientists on four continents told AFP.
This would happen as slow-growing hard corals -- the primary reef builders that underpin the ecosystem -- die off, leaving behind white skeletons without living tissue.
Gradually, these would be covered by algae and colonised by simpler organisms better able to withstand hotter oceans, like sponges, mussels, and weedy soft corals like sea fans.
"There will be less winners than there are losers," said Tom Dallison, a marine scientist and strategic advisor to the International Coral Reef Initiative.
These species would dominate this new underwater world. The dead coral beneath -- weakened by ocean acidification, and buffeted by waves and storms -- would erode over time into rubble.
"They will still exist, but they will just look very different. It is our responsibility to ensure the services they provide, and those that depend on them, are protected," Dallison said.
- Dark horizon -
One quarter of all ocean species live among the world's corals.
Smaller, sparser, less biodiverse reefs simply means fewer fish and other marine life.
The collapse of reefs threatens in particular the estimated one billion people who rely on them for food, tourism income, and protection from coastal erosion and storms.
But if protected and managed properly, these post-coral reefs could still be healthy, productive, attractive ecosystems that provide some economic benefit, said Obura.
So far, the picture is fuzzy -- research into this future has been very limited.
Stretched resources have been prioritised for protecting coral and exploring novel ways to make reefs more climate resilient.
But climate change is not the only thing threatening corals.
Tackling pollution, harmful subsidies, overfishing and other drivers of coral demise would give "the remaining places the best possible chance of making it through whatever eventual warming we have", Obura said.
Conservation and restoration efforts were "absolutely essential" but alone were like "pushing a really heavy ball up a hill, and that hill is getting steeper", he added.
Trying to save coral reefs "is going to be extremely difficult" as long as we keep pouring carbon into the atmosphere, said Jean-Pierre Gattuso, an oceans expert from France's flagship scientific research institute, CNRS.
But some coral had developed a level of thermal tolerance, he said, and research into restoring small reef areas with these resilient strains held promise.
"How do we work in this space when you have this sort of big dark event on the horizon? It's to make that dark event a little brighter," said Dallison.
np/mh/phz
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News.com.au
4 days ago
- News.com.au
In a hotter future, what comes after coral reefs die?
The fate of coral reefs has been written with a degree of certainty rare in climate science: at 1.5 degrees Celsius of global warming, most are expected to die. This is not a far-off scenario. Scientists predict that the rise of 1.5 Celsius (2.7 Fahrenheit) will be reached within a decade and that beyond that point, many coral simply cannot survive. It is important to accept this and ask what next "rather than trying to hold onto the past", said David Obura, chair of IPBES, the UN's expert scientific panel on biodiversity. "I wish it were different," Obura, a Kenyan reef scientist and founding director of CORDIO East Africa, a marine research organisation, told AFP. "We need to be pragmatic about it and ask those questions, and face up to what the likely future will be." And yet, it is a subject few marine scientists care to dwell on. "We are having a hard time imagining that all coral reefs really could die off," said Melanie McField, a Caribbean reef expert, who described a "sort of pre-traumatic stress syndrome" among her colleagues. "But it is likely in the two-degree world we are rapidly accelerating to," McField, founding director of the Healthy Reefs for Healthy People Initiative, told AFP. When stressed in hotter ocean waters, corals expel the microscopic algae that provides their characteristic colour and food source. Without respite, bleached corals slowly starve. At 1.5C of warming relative to pre-industrial times, between 70 and 90 percent of coral reefs are expected to perish, according to the IPCC, the global authority on climate science. At 2C, that number rises to 99 percent. Even with warming as it stands today -- about 1.4C -- mass coral death is occurring, and many scientists believe the global collapse of tropical reefs may already be underway. - What comes next - Obura said it was not pessimistic to imagine a world without coral reefs, but an urgent question that scientists were "only just starting to grapple with". "I see no reason to not be clear about where we are at this point in time," Obura said. "Let's be honest about that, and deal with the consequences." Rather than disappear completely, coral reefs as they exist today will likely evolve into something very different, marine scientists on four continents told AFP. This would happen as slow-growing hard corals -- the primary reef builders that underpin the ecosystem -- die off, leaving behind white skeletons without living tissue. Gradually, these would be covered by algae and colonised by simpler organisms better able to withstand hotter oceans, like sponges, mussels, and weedy soft corals like sea fans. "There will be less winners than there are losers," said Tom Dallison, a marine scientist and strategic advisor to the International Coral Reef Initiative. These species would dominate this new underwater world. The dead coral beneath -- weakened by ocean acidification, and buffeted by waves and storms -- would erode over time into rubble. "They will still exist, but they will just look very different. It is our responsibility to ensure the services they provide, and those that depend on them, are protected," Dallison said. - Dark horizon - One quarter of all ocean species live among the world's corals. Smaller, sparser, less biodiverse reefs simply means fewer fish and other marine life. The collapse of reefs threatens in particular the estimated one billion people who rely on them for food, tourism income, and protection from coastal erosion and storms. But if protected and managed properly, these post-coral reefs could still be healthy, productive, attractive ecosystems that provide some economic benefit, said Obura. So far, the picture is fuzzy -- research into this future has been very limited. Stretched resources have been prioritised for protecting coral and exploring novel ways to make reefs more climate resilient. But climate change is not the only thing threatening corals. Tackling pollution, harmful subsidies, overfishing and other drivers of coral demise would give "the remaining places the best possible chance of making it through whatever eventual warming we have", Obura said. Conservation and restoration efforts were "absolutely essential" but alone were like "pushing a really heavy ball up a hill, and that hill is getting steeper", he added. Trying to save coral reefs "is going to be extremely difficult" as long as we keep pouring carbon into the atmosphere, said Jean-Pierre Gattuso, an oceans expert from France's flagship scientific research institute, CNRS. But some coral had developed a level of thermal tolerance, he said, and research into restoring small reef areas with these resilient strains held promise. "How do we work in this space when you have this sort of big dark event on the horizon? It's to make that dark event a little brighter," said Dallison. np/mh/phz
ABC News
5 days ago
- ABC News
These Pacific Islands are building walls to stop rising seas. Will it work?
The sea used to wreak havoc as it crashed into Simeona Tapeneko's village in Samoa. Water would flood the houses in Lauli'i, on the north coast of the country's most populated island, overwhelming an old seawall built offshore. "Many things — including our homes — were severely damaged," Mr Tapeneko said. "The waves also destroyed the graves of deceased family members." When builders laid the last rock of a new seawall there in May, ending six months of construction, Lauli'i breathed a collective sigh of relief. Mr Tapeneko said the $1.9 million wall, funded by the New Zealand government, would protect the homes from storm surges. It's one of many Pacific Island communities building seawalls to defend themselves against rising sea levels. One of Marshall Islands' most populated islands, Ebeye, is buttressing its coast with a wall of rock shipped from Dubai and funded by the World Bank and Green Climate Fund. New seawalls also protect low-lying atolls in Tuvalu, and more will appear in Kiribati, Tonga, Solomon Islands, Fiji and other island nations, many with funding from the Australian government and international development organisations. They're a source of hope for countries grappling with sea level rise — which scientists say will continue even if the world limits global temperature rises to 1.5 degrees Celsius above pre-industrial times. Coastal engineers say places like the Netherlands have long used engineering to hold back the sea from low-lying lands — and that the Pacific could do the same. But researchers in climate change adaptation say seawalls are usually a costly, short-term fix in a region with limited money. "A seawall along an eroding coastline is really only a stopgap measure, because we know that [sea level rise] is projected to continue well beyond the end of this century, perhaps by about another 200 or 300 years," Patrick Nunn, a University of Sunshine Coast climate scientist, said. Not far from the shores of Lauli'i, its old seawall sits mostly submerged in water. Leota Vaimauga, a village chief, estimates it lasted for 10-15 years before it was overwhelmed by the sea. And while he's relieved the village has a new seawall, he expects Lauli'i will need to replace it in another decade, depending on the weather and the stability of the new barrier. Climate adaptation researchers say seawalls have a clear downside that makes them hard to sustain in rural areas. "You have to keep elevating them, have to keep extending them, and so they're very economically costly," Jon Barnett, a climate adaptation researcher at the University of Melbourne, said. Most seawalls in rural coastal areas are funded and built by local communities, and have been too expensive to maintain, researchers say. Professor Nunn calculates that on average, the structures will collapse after 18 to 24 months. A study he co-authored in 2021 describes the Pacific's rural coastlines as "littered with the remains of collapsed seawalls". Climate adaptation researchers also say seawalls have side effects, like diverting erosion to other parts of the coast, forcing waves to scour the seafloor at their seaward side, and pooling water on their landward side. Professor Nunn said rural villages in the Pacific's higher volcanic islands could better use the labour and resources spent on seawalls on a longer-term solution — relocating further inland and upslope. But he said seawalls can offer important psychological benefits for communities losing land to rising seas. They also provide time for them to consider whether to relocate, researchers and coastal engineers say. It's something Queensland University of Technology climate change adaptation researcher, Annah Piggott-McKellar, observed in one Fiji village that relocated after building a series of seawalls. "Land is … a way of life. It's a part of who people are," she said. But Dr Piggott-McKellar said there was also a risk that seawalls give false hope. "Having that realistic conversation and understanding of what a seawall might be there to do is going to be important." For the Pacific's low-lying atolls, new seawalls come with fanfare. In Marshall Islands, 65,000 tonnes of rock shipped from the United Arab Emirates will form a new 1.81 kilometre barrier on the seaward side of Ebeye island. Hall Contracting, which is building the multi-million-dollar seawall, said it was due to be completed by December. "The houses in Ebeye are built right up against the ocean … in large storm events those houses can be affected," company CEO and director Cameron Hall said. "This seawall will protect them." Mr Hall said seawalls have an important role to play for Pacific Island nations as sea levels rise. "It's a problem that developed nations have created … and if there's an engineering solution, why wouldn't we do it for them?" The work is logistically challenging, requiring builders to move machinery to remote atolls, and source material for the seawalls. In Tuvalu, Hall Contracting dredged sand from the lagoon by the capital Funafuti to build seven hectares of new or "reclaimed" land protected by a seawall of sandbags. It also constructed a seawall of interlinked hexagonal concrete blocks along part of the coast at Nanumea, another Tuvalu atoll. It's all part of Tuvalu's coastal adaptation project, funded by the Tuvaluan and Australian governments and the Green Climate Fund, aiming to keep the nation inhabitable. But a group of Nanumeans is championing a proposal to save their home for the longer-term. Local engineer Truman Lomi has worked on a concept for the Nanumea Salvation Seawall Project for years. It involves building a barrier around the entire island — rather than just a section. He said the barrier would protect the entire coast from large, powerful waves. For now, it requires funding for a feasibility study. His granddaughter Ashleigh Chatelier, a member of the Nanumea Salvation Seawall group, said the project also carried a message about Tuvalu's ability to adapt to climate change. "Unfortunately, we are restricted in terms of the funding of this project, but the reality is that this is a community-led resilience project and it essentially has come from the roots of Nanumea." Countries have long used engineering to protect, or reclaim, land from the sea. In the Netherlands, dams and dykes keep vast, low-lying areas from flooding. The Maldives, in the Indian Ocean, has reclaimed land from rising seas, although at huge financial and environmental costs. "An engineering solution is possible," Francois Flocard, coastal engineer at the University of New South Wales' Water Research Laboratory, said. "It's [about] understanding, as a community and as a society, where does it make sense to be applied?" Professor Barnett says there are other options for communities where seawalls are too costly to build and maintain. One is to try restoring and conserving ecosystems in a way that lets islands respond naturally to sea level rise. "That doesn't mean they're going to be easy to live on," he said. "Shorelines are going to change, the topography of islands is going to change. Some bits are going to erode, some bits are going to grow. "But the adaptation options there are probably much cheaper." Some Pacific Island nations are also creating nature-based barriers, using mangroves, sloping rock walls and vetiver grass to block rising seas. In some ways, Professor Barnett said, all action is good action compared to the paralysis on climate change adaptation in some countries. Leaders in countries like Tuvalu are being told there is only decades until their nations are uninhabitable, he said. "You've got to protect the capital. You have to have an airport. You have to have a hospital. You have to have schools. "It seems perfectly reasonable to engage in the kinds of urban defensive strategies."
News.com.au
25-05-2025
- News.com.au
Global warning over fungi ‘that could eat you from inside out'
Researchers have warned that a mysterious fungi that kill millions of people worldwide each year may soon spread significantly further - including in Australia. In a chilling echo of the popular video game TV series adaptation The Last of Us – a post-apocalyptic story about survival in a world ravaged by a fungal infection – the fungi could soon spread across North America, Europe, China and Russia. That's according to scientists from Manchester University who used computer simulations to forecast how Aspergillus, a group of fungi that can cause a life-threatening lung disease called aspergillosis, may move globally. The new Manchester University study, which has yet to be peer-reviewed, studied three pathogenic Aspergillus species: A. fumigates, A. flavus, and A. niger, under different climate scenarios. A. fumigates was found to be more common in temperate climates, while A. flavus and A. niger dominate in warmer regions. According to future climate scenarios, all three species could shift north due to global warning, particularly under severe warming events. The use of fossil fuels could also speed the spread. 'Fungi are relatively under-researched compared to viruses and parasites, but these maps show that fungal pathogens will likely impact most areas of the world in the future,' lead author of the research Norman van Rhijn told I mpact on Australia When it comes to how Australia will be impacted by the fungi, Dr van Rhijn said the nation should expect cases to climb, especially around coastal areas. 'The model predicts there will be a slight increase in suitability for Aspergillus flavus – as it mostly shifts from inland towards the coast (and therefore will be more closer to a lot of people),' Dr van Rhijn said. 'The other two species, Aspergillus fumigates and niger remain relatively consistent as they are most common in Australia along the coastal lines already and remain there.' So what is Aspergillus and how deadly is it? A group of living organisms that include moulds, yeasts, and mushrooms, fungi is all around us. Some types of fungi are useful – such as yeast used in baking – however others can cause severe infections in humans, livestock, and plants. Fungi spreads in spores through the air that we breathe and lives inside our bodies as well as in the soil. If the body's immune system cannot clear the fungi spores it breaths in, the fungi 'starts to grow and basically kind of eat you from the inside out, saying it really bluntly', Dr van Rhijn warned. He explained that fungi are decomposers or recyclers in nature and are extremely good at cleaning up organic material such as leaves falling from the trees or dead animals. 'They can obviously do the same to people when they come into contact. That means that people that are unable to effectively deal with the fungus through impaired immune systems or other diseases, are prone to have the fungus grow in them.' There is still a lot to learn about fungi, and more than 90 per cent types of fungi are estimated to be unknown to science. They have a devastating impact. Globally, there are 6.5 million invasive fungal infections a year, associated with approximately 3.8 million mortalities. Of those deaths, 2.5 million are directly attributable to these infections, according to the International Society for Infectious Diseases. An estimated 2.1 million people develop invasive aspergillosis annually, with a mortality rate of 85.2 per cent, while chronic pulmonary aspergillosis affects 1.84 million people annually, causing 340,000 deaths. Those with weakened immune systems such as transplant recipients or those undergoing chemotherapy, and people with asthma, cystic fibrosis and COPD, are more vulnerable to the fungus. 'Fungal pathogens pose a serious threat to human health by causing infections and disrupting food systems.' Viv Goosens, research manager at Wellcome Trust, which funded the research, told Sky News. 'Climate change will make these risks worse. To address these challenges, we must fill important research gaps.' Results of the study The study explored how the existing habitats that are suitable for the fungi could spread or shrink under different global warming predictions. The world is on track to heat up by 2.6-3.1C, and the scientists found that even with 2C of warming, the fungi types Aspergillus fumigates and flavus would spread further northwards into the UK and Scandinavia. Aspergillus fumigates could spread by 16 per cent – possibly increasing by 77.5 per cent by 2100. The fungus would likely die in southern Europe. Meanwhile, Aspergillus niger could spread a further 10 per cent in Europe, while temperatures in Africa may become so high that some fungi would cease to exist. Of further concern, a warming world could also boost the fungi's temperature tolerance, allowing them to survive better inside people's bodies. 'Australians should be aware' The fungi has been detected in Australia, with those around the nation warned to be on the lookout for symptoms. 'Although the term Aspergillosis may sound like a tongue twister, it's something that all Australians should be aware of, particularly given our warm, humid atmosphere which is ideal for the formation of mould,' Australia Wide First Aid advises on its website. 'This bothersome infection, which is brought on by the common mould Aspergillus, can be rather serious, especially for people who have compromised immune systems or respiratory problems.' It noted that Aspergillus, commonly found in our surroundings, grows best in environments with lots of organic matter such as dust in homes, soil, decomposing leaves, and compost. In 2022, the World Health Organization added Aspergillus flavus to its critical group of fungal pathogens due to its public health impact and antifungal resistance risk.
