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Dairy cattle seem to survive infection with the H5N1 strain of influenza virus, which has killed millions of wild birds.Credit: Ben Brewer/Reuters
As the first-known outbreak of H5N1 avian influenza in cows continues in the United States, scientists are increasingly concerned that the animals will become a permanent reservoir for the virus, giving it more chances to mutate and jump to humans. Cows usually survive infection, which could make them a good place for viruses to acquire mutations by swapping genetic material — and there are a lot of cows. One dairy worker in Texas has definitely already been infected with H5N1 (with only mild symptoms) but there could be far more unidentified cases because testing of people is limited.
A new version of DeepMind’s AlphaFold tool gives scientists the ability to predict protein structures during interactions with other molecules. The tool could be transformative for drug discovery because it can predict the shape of proteins that contain function-altering modifications, or their structure alongside those of DNA, RNA and other cellular players that are crucial to a protein’s duties. “This is just revolutionary,” says biochemist Frank Uhlmann. “It’s going to democratize structural-biology research.” Access to the AlphaFold3 server, however, is limited — partly to protect the advantage of DeepMind’s own drug-discovery spin-off company.
The United States has introduced a new policy that provides stricter oversight of biological experiments that could be misused or spark a pandemic. It took more than four years of deliberations to develop a system that evaluates the risks and benefits of pathogen research without paralysing fundamental science. The policy, which comes into effect next year, sets a standard that might inspire other countries to re-evaluate their current approaches, says biosecurity researcher Filippa Lentzos.
Mexico has two scientist-candidates for president in its elections next month. Leading in the polls is environmental engineer Claudia Sheinbaum Pardo, who has vowed to “make Mexico a scientific and innovation power”. Sheinbaum Pardo would be the first woman and first environmental engineer to lead Mexico. Her rivals include computer engineer Xóchitl Gálvez Ruiz, who criticises Sheinbaum Pardo for not challenging current president Andrés Manuel López Obrador’s policies, including support for Mexico’s oil industry, a controversial science law and cuts to science spending. Some academics echo those concerns: “Is she going to continue López Obrador’s attacks on science or will she … radically change?” asks mathematician Raúl Rojas González.
Rejuvenating the immune system seems to revitalise many organs in an animal’s body — at least in mice. This raises the tantalising prospect of treating immune ageing to control age-related diseases. But interfering with the highly complex immune system can be perilous. Pioneers are setting their sights on low-risk but important goals, such as strengthening older people’s responses to vaccinations and boosting the efficiency of cancer immunotherapies.
In The Light Eaters, journalist Zoë Schlanger takes a deep dive into plant intelligence and consciousness — topics that were long considered pseudoscience. Some cautious studies have popped up, for example of a vine that changes the shape of its leaves to mimic those of neighbouring plants. “As a plant scientist, I am fascinated by what draws us to wanting to define plants as sentient or conscious — or not — through the lens of our limited human understanding of those terms,” writes reviewer Beronda Montgomery.
Do you have a work dilemma you’d like some help with? E-mail [email protected]
QUOTE OF THE DAY
In 2009, neuroscientist Larry Young wrote in Nature about his influential research into how the hormone oxytocin influences complex social behaviours such as the parent-infant bond and romantic love. Young has died, aged 56. (Nature | 5 min read)
Today, I want to share news of the Nature Awards Microbiome Accelerator for researchers with aspirations to translate their microbiome research to transform health outcomes. Four applicants will each receive US$10,000 and entry to an immersive residential programme. Learn more and apply here — the deadline is 24 June.
With contributions by Katrina Krämer, Smriti Mallapaty and Sarah Tomlin
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• Nature Briefing: Microbiology — the most abundant living entities on our planet — microorganisms — and the role they play in health, the environment and food systems.
Stem-cell researcher Carolina Florian didn’t trust what she was seeing. Her elderly laboratory mice were starting to look younger. They were more sprightly and their coats were sleeker. Yet all she had done was to briefly treat them — many weeks earlier — with a drug that corrected the organization of proteins inside a type of stem cell.
When technicians who were replicating her experiment in two other labs found the same thing, she started to feel more confident that the treatment was somehow rejuvenating the animals. In two papers, in 2020 and 2022, her team described how the approach extends the lifespan of mice and keeps them fit into old age1,2.
The target of Florian’s elixir is the immune system. The stem cells she treated are called haematopoietic, or blood, stem cells (HS cells), which give rise to all immune cells. As blood circulates, the mix of cells pervades every organ, affecting all bodily functions.
But the molecular composition of the HS cells changes with age, and this distorts the balance of immune cells that they produce. “Fixing the drift in them that occurs with time seems to fix a lot of the problems of ageing — not only in the immune system but also in the rest of the body,” says Florian, who is now at the Bellvitge Biomedical Research Institute in Barcelona, Spain.
In March3, another team showed that restoring the balance between two key types of immune cell gives old mice more youthful immune systems, improving the animals’ ability to respond to vaccines and to stave off viral infections.
How to make an old immune system young again
Other scientists have used different experimental approaches to draw the same conclusion: rejuvenating the immune system rejuvenates many organs in an animal’s body, at least in mice. And, most intriguingly, evidence suggests that immune-system ageing might actually drive the ageing of those organs.
The potential — helping people to remain healthy in their later years — is seductive. But translating this knowledge into the clinic will be challenging. Interfering with the highly complex immune system can be perilous, researchers warn. So, at first, pioneers are setting their sights on important yet low-risk goals such as improving older people’s responses to vaccinations and improving the efficiency of cancer immunotherapies.
“The prospect that reversing immune ageing may control age-related diseases is enticing,” says stem-cell scientist Vittorio Sebastiano at Stanford Medical School in California. “But we are moving forward cautiously.”
Fading immunity
The human immune system is a complex beast whose multitudinous cellular and molecular components work together to shape development, protect against infections, help wounds to heal and eliminate cells that threaten to become cancerous. But it becomes less effective as people age and the system’s composition starts to change. In older age, people become susceptible to a range of infectious and non-infectious diseases — and more resistant to the protective power of vaccines.
The immune system has two main components: a fast-acting innate system, which destroys invading pathogens indiscriminately, and a more-precise adaptive immune system, whose components learn to recognize specific foreign bacteria and viruses and generate antibodies against them.
The HS cells in the bone marrow spawn the immune cells of both arms of the system. They differentiate into two main classes — lymphoid and myeloid — which go on to differentiate further. Lymphoid cells are mostly responsible for adaptive immunity, and include: B cells, which produce antibodies; T cells, which help to attack invaders and orchestrate complex immune responses; and natural killer cells, which destroy infected cells. Myeloid cells include a raft of cell types involved mostly in innate immunity.
Proteins inside immune-cell-generating stem cells become more symmetrical with age (right).Credit: Eva Mejia-Ramirez
One of the earliest changes in the immune system as people age is the shrinking of the thymus, which begins after puberty. This organ is the crucible for T cells, but a lot of the tissue has turned to fat by the time people hit their 30s, slashing the production of new T cells and diminishing the power of the immune system. What’s more, the function of T cells alters as they age and become less specialized in their ability to recognize infectious agents.
The proportions of different types of immune cell circulating in the blood also changes. The ratio of myeloid to lymphoid cells skews markedly towards myeloid cells, which can drive inflammation. Moreover, increasing numbers of immune cells become senescent, meaning that they stop replicating but don’t die.
Any cell in the body can become senescent, typically when damaged by a mutation. Once in this state, cells start to secrete inflammatory signals, flagging themselves for destruction. This is an important anticancer and wound-healing mechanism that works well in youth. But when too much damage accumulates with ageing — and immune cells themselves also become senescent — the mechanism breaks down. Senescent immune cells, attracted by the inflammatory signals from senescent tissue, secrete their own inflammatory molecules. So not only do they fail to clean up properly, but they also add to the inflammation that damages surrounding healthy tissue. The phenomenon is known as ‘inflammaging’.
“It becomes a terrible positive feedback — a never-ending dance of destruction,” says immunologist Arne Akbar at University College London.
And evidence suggests that this feedback loop is kicked off by the immune system. In a series of experiments in mice4, Laura Niedernhofer at the University of Minnesota in Minneapolis has shown that immune-cell senescence actually drives senescence in other tissues. “These cells are extremely dangerous,” she says.
Her team used genetic methods to eliminate an important DNA-repair enzyme in the immune system of the mice. The animals remained healthy until adulthood but then, unable to correct accumulating mutations, various types of immune cell started to become senescent.
A few months later, increasing numbers of cells in organs such as the liver and kidney also fell into senescence, and the organs showed signs of damage. These effects were all reversed when the scientists gave the mice immune cells from the spleens of young, healthy mice.
All of this suggests that fixing the characteristics of immune-system ageing could help to prevent or mitigate diseases of ageing, says Niedernhofer.
Battling senescence
Many scientists are trying to do just that, from very different angles. Lots of the approaches hint that very short treatments of the immune system might have long-term effects, keeping side effects to a more manageable minimum.
One approach is to tackle senescent immune cells head on, using drugs to either remove them or block the inflammatory factors they secrete. “Senescent immune cells have long been known to be very modifiable in humans,” says Niedernhofer. “They go up if you smoke and down if you exercise.”
Are your organs ageing well? The blood holds clues
Some drugs — such as dasatinib, which is approved for the treatment of some cancers, and quercetin, which is marketed as an antioxidant dietary supplement but not approved as a drug — are known to reduce the age-related acceleration of senescence, and dozens of clinical trials are testing their impact on various age-related diseases. Niedernhofer herself is involved in a small clinical trial on older people with sepsis, a condition that becomes more deadly with age.
Her team is also doing experiments to assess which of the many types of immune cell is the most important in driving senescence in the body, which should help in the design of more precise therapies. Two types — T cells and natural killer cells — are emerging as key contenders, she says. She plans to screen natural products and drugs already approved for use by the US Food and Drug Administration for their ability to interact with those types of immune cell in senescence.
Akbar thinks that targeting inflammation itself might be as effective as targeting the senescent cells. He and his colleagues did a study in healthy volunteers using the investigational compound losmapimod, which blocks an enzyme involved in the production of inflammatory molecules called cytokines. They treated the volunteers with the drug for four days, and then, over the course of a week, measured their skin responses to an injection of the virus that causes chickenpox. Most people are exposed to this virus during their lives and it frequently lingers in the body. But with age, people tend to lose their immunity to it, and it can then manifest as shingles. The drug restored the immune response in the skin in older volunteers to a level similar to that seen in the younger volunteers5. In unpublished work, Akbar has found the same robust skin results up to three months later.
“Temporarily blocking inflammation in this way to allow the immune system to function might similarly boost the response of older patients to flu vaccinations,” says Akbar.
Immune boost
The value of priming the aged immune system before administering a vaccine has been demonstrated in a series of clinical trials led by researcher Joan Mannick, chief executive of Tornado Therapeutics, which is headquartered in Boston, Massachusetts. Those trials tested analogues of the drug rapamycin and other drugs with similar mechanisms, which target the immune system and are approved for prevention of organ transplant rejection and for the treatment of some cancers. The drugs block an enzyme, called mTOR, that is crucial for many physiological functions and which becomes dysregulated in old age.
For several weeks before receiving their influenza vaccinations, trial participants were treated with doses of the drugs that were low enough to avoid side effects. This treatment regimen improved their responses to the vaccine, and boosted the ability of their immune systems to resist viral infections in general.
Vaccines tend to work less efficiently in older adults, but new approaches could boost their power.Credit: Hector Vivas/Getty
But rapamycin can raise susceptibility to infection and affect metabolism, so Mannick is planning trials with similar drugs that might have a safer profile. “But there are all sorts of different ways to try to improve the immune system,” she notes.
One other way is to try to restore the function of the thymus to maintain the production of new T cells. Immunologist Jarrod Dudakov at the Fred Hutchinson Cancer Center in Seattle, Washington, is researching the basic biology of thymus cells to try to work out how they regenerate themselves after stressful assaults. “It’s all a bit early to see how this understanding will translate into the clinic,” he says. But he thinks that maintaining the ability of the thymus to generate a broad repertoire of T cells will be “foundational”.
Others are trying to combat ageing by generating thymic tissue from pluripotent stem cells for eventual transplantation. But Greg Fahy, chief scientific officer at Intervene Immune in Torrance, California, says he sees no need to wait for these long-term prospects to come to fruition, because an available drug — synthetic growth hormone — is already known to regenerate thymus tissue. He is doing a series of small studies on healthy volunteers using growth hormone as part of a cocktail of compounds. Early results indicate that the participants show increased levels of functional thymic tissue, and that their epigenetic clock — a biomarker of ageing — reverses by a couple of years6. Fahy is now extending the trial to look at whether the drug cocktail also improves physical fitness in a larger group of volunteers.
Turn back time
Another approach, not yet in the clinic, is to partially reprogram immune cells, to try to turn back the clock in cells that have become senescent. This involves transiently exposing the cells in a dish to a cocktail of transcription factors known to induce a pluripotent state in adult cells.
Reversal of biological clock restores vision in old mice
Sebastiano and his colleagues have shown in human cells that this process corrects the epigenetic changes that occur with ageing7. He has co-founded a start-up company to use the technique to try to counteract a problem in a cancer therapy known as CAR T, in which T cells are engineered outside the body to target and destroy a person’s cancer. But the T cells can turn senescent before they can be returned to the person. Rejuvenating them during the generation process would make production quicker and more robust, says Sebastiano.
Florian’s approach, too, aims to produce healthier immune cells — inside the body1,2. HS cells in the blood rack up epigenetic changes, and their environment also changes as they age. This causes proteins in the cells to arrange themselves more symmetrically — a process known as polarization — which shifts the balance of stem-cell differentiation in favour of myeloid cells over lymphoid cells. Florian’s studies used a four-day treatment with a compound, called CASIN, that inhibits one part of this process to correct the polarization, and helped the mice to live longer.
The team saw the same life-extending effects when HS cells from old mice given CASIN were transplanted into old mice that hadn’t received the treatment. “This very small step had a large impact,” says Florian.
Florian next hopes to bring her work to the clinic. As a first case study, she thinks her drug might support regeneration of the immune system after people receive chemotherapy for cancer.
How old?
Research on immune ageing faces some fundamental challenges. One is shared with ageing studies in all organs — the inability to measure ageing precisely.
“We don’t know in a quantitative, measurable, predictive way what ageing means at the molecular level in different cell types,” says Sebastiano. “Without those benchmarks, it is very hard to show rejuvenation.” Last year, a consortium of academics got together to begin developing a consensus on biomarkers of ageing — which will be essential when scientists come to seek approval from regulatory agencies for anti-ageing therapies.
Another challenge is the difficulty in pinning down what makes one immune cell unique. Until recently, it has been hard to demonstrate which subtypes of immune cells live where, and how they change with time.
But technologies such as single-cell RNA sequencing, which quantitatively measures the genes being expressed in individual cells, have tightened up analysis. A large study of immune cells in the blood of mice and humans across a range of ages published last November, for example, revealed 55 subpopulations. Just twelve of those changed with age8.
With so many strands of research coming together, scientists are cautiously hopeful that the immune system will indeed prove to be a key lever in healthy ageing. Don’t expect an elixir of youth any time soon, says Florian — by definition, ageing research takes a long time. “But there is such great potential for translation.”
Jaime Guevara-Aguirre (back left) and Valter Longo (back right) pose with several of the Laron study participants.Credit: Courtesy Jaime Guevara-Aguirre & Valter Longo
A rare form of dwarfism that affects only 400–500 people worldwide has caught the interest of scientists who study ageing and metabolic diseases. This is because a series of studies have associated the condition with a number of positive health effects, including protection against diabetes, cancer1 and cognitive decline2. Mice with a similar condition live for about 40% longer than do control animals3.
Although it is unclear whether people with the condition, known as Laron syndrome or growth-hormone-receptor deficiency, live longer on average than those without it, a study published today in Med shows that they do seem to be at lower risk of developing cardiovascular disease4. They have lower blood pressure, reduced artery fat build-up and a less thick carotid artery wall than do relatives who do not have the syndrome.
“In some sense, this was the most important of all studies,” says Valter Longo, a biogerontologist at the University of Southern California in Los Angeles and a co-author of today’s paper. “It was the last piece missing in showing that they seem to be protected from all the major age-related diseases.” Studying the details of the syndrome, he adds, might inspire the development of drugs or diets with similar protective effects.
From Ecuador to the world
The study examined 24 people with Laron syndrome and 27 of their relatives, all of whom live in Ecuador, which is home to about one-third of all people with the condition, says Jaime Guevara-Aguirre, an endocrinologist at the University of San Francisco in Quito, Ecuador, and a co-author of the study. He has been following this group for more than 30 years, since he identified a cluster of cases in a few secluded villages in the Andes Mountains.
Dwarfism may stymie diseases of old age
People with Laron syndrome have a deficiency in the growth hormone receptor that prevents their bodies from properly using the hormone. These individuals have normal or high levels of growth hormone but low levels of insulin-like growth factor-1 (IGF-1), which normally helps growth hormone to promote the growth of bones and tissues.
Because having low IGF-1 levels has been associated with a higher risk of cardiovascular disease5, “everybody assumed that people with Laron probably had a lot of heart and cardiovascular problems, too”, says Longo. A previous study by the same group found that people with Laron syndrome had a normal rate of death from cardiovascular disease1. But when Guevara-Aguirre investigated some of the deaths attributed to heart attacks, he found inconsistencies. “People in those little towns sometimes attribute any death without an explanation to myocardial infarction because it’s the easiest thing,” he says.
The researchers performed a series of tests that showed that people with Laron syndrome actually had normal or improved levels of cardiovascular-disease risk compared with their relatives without the disorder.
“These are preliminary results from a very small number, but they’re interesting observations,” says Ravi Savarirayan, a clinical geneticist and researcher at Murdoch Children’s Research Institute in Melbourne, Australia. “And I think they will need to be replicated in much larger cohorts.” Savarirayan and his colleagues found similar results6 in patients with another type of dwarfism called achondroplasia. “It was just really interesting when I looked at this paper and saw a lot of similarities between the two,” he says.
Endocrinologist Manuel Aguiar-Oliveira at the Federal University of Sergipe in Brazil, who studies another rare mutation that causes short stature, also found similar cardiovascular protective effects7 in a group of people he has been following for more than 30 years in Brazil. “The data are very similar,” he says.
Researchers are intrigued by the possibility that people with Laron syndrome might live longer than average. So far, Longo, Guevara-Aguirre and their colleagues have found no sign of this, but they still hope to find a longevity signal if they compare people with the syndrome with their unaffected siblings. “I’m still trying to get the funds to do this study,” says Guevara-Aguirre.
Drug inspiration?
Haim Werner, a geneticist at Tel Aviv University in Israel who studies the protective effects of Laron syndrome against cancer, says that the current work is important in helping to characterize genes and pathways that might confer protection against cardiovascular disease. “Delineation of these genes is of crucial importance for future nutritional or pharmacological interventions,” he says.
Is a boost to height a boost to health? Dwarfism therapies spark controversy
Longo hopes that the recent results might inspire the development of new strategies to prevent cardiovascular disease in people without the condition, perhaps an oral drug to bring IGF-1 levels down by targeting the growth hormone receptor. “We just have to find out how to do it safely, so that we don’t make things worse,” he says. Aguiar-Oliveira is less enthusiastic about blocking hormones to mimic the positive effects in unaffected people. “I think this type of intervention may be risky,” he says.
The researchers also want to help people with Laron syndrome. Longo and Guevara-Aguirre have been advocating for pharmaceutical companies and the Ecuadorian government to provide IGF-1 to children and adolescents with the syndrome to promote growth, which some research suggests might have benefits for people with dwarfism. The researchers have also begun testing a dietary approach that they hope will improve the growth of children with the syndrome. And Guevara-Aguirre has been providing free medical care to the group. “They still call me every week with one problem here or there,” he says. “Fortunately, they don’t have many.”
One of world’s largest oil platforms, the North Sea’s Gullfaks C, sits on immense foundations, constructed from 246,000 cubic metres of reinforced concrete, penetrating 22 metres into the sea bed and smothering about 16,000 square metres of sea floor. The platform’s installation in 1989 was a feat of engineering. Now, Gullfaks C has exceeded its expected 30-year lifespan and is due to be decommissioned in 2036. How can this gargantuan structure, and others like it, be taken out of action in a safe, cost-effective and environmentally beneficial way? Solutions are urgently needed.
Many of the world’s 12,000 offshore oil and gas platforms are nearing the end of their lives (see ‘Decommissioning looms’). The average age of the more than 1,500 platforms and installations in the North Sea is 25 years. In the Gulf of Mexico, around 1,500 platforms are more than 30 years old. In the Asia–Pacific region, more than 2,500 platforms will need to be decommissioned in the next 10 years. And the problem won’t go away. Even when the world transitions to greener energy, offshore wind turbines and wave-energy devices will, one day, also need to be taken out of service.
Source: S. Gourvenec et al. Renew. Sustain. Energy Rev.154, 111794 (2022).
There are several ways to handle platforms that have reached the end of their lives. For example, they can be completely or partly removed from the ocean. They can be toppled and left on the sea floor. They can be moved elsewhere, or abandoned in the deep sea. But there’s little empirical evidence about the environmental and societal costs and benefits of each course of action — how it will alter marine ecosystems, say, or the risk of pollution associated with moving or abandoning oil-containing structures.
So far, politics, rather than science, has been the driving force for decisions about how to decommission these structures. It was public opposition to the disposal of a floating oil-storage platform called Brent Spar in the North Sea that led to strict legislation being imposed in the northeast Atlantic in the 1990s. Now, there is a legal requirement to completely remove decommissioned energy infrastructure from the ocean in this region. By contrast, in the Gulf of Mexico, the idea of converting defunct rigs into artificial reefs holds sway despite a lack of evidence for environmental benefits, because the reefs are popular sites for recreational fishing.
A review of decommissioning strategies is urgently needed to ensure that governments make scientifically motivated decisions about the fate of oil rigs in their regions, rather than sleepwalking into default strategies that could harm the environment. Here, we outline a framework through which local governments can rigorously assess the best way to decommission offshore rigs. We argue that the legislation for the northeast Atlantic region should be rewritten to allow more decommissioning options. And we propose that similar assessments should inform the decommissioning of current and future offshore wind infrastructure.
Challenges of removing rigs
For the countries around the northeast Atlantic, leaving disused oil platforms in place is an emotive issue as well as a legal one. Environmental campaigners, much of the public and some scientists consider anything other than the complete removal of these structures to be littering by energy companies1. But whether rig removal is the best approach — environmentally or societally — to decommissioning is questionable.
Energy crisis: five questions that must be answered in 2023
There has been little research into the environmental impacts of removing platforms, largely owing to lack of foresight2. But oil and gas rigs, both during and after their operation, can provide habitats for marine life such as sponges, corals, fish, seals and whales3. Organisms such as mussels that attach to structures can provide food for fish — and they might be lost if rigs are removed4. Structures left in place are a navigational hazard for vessels, making them de facto marine protected areas — regions in which human activities are restricted5. Another concern is that harmful heavy metals in sea-floor sediments around platforms might become resuspended in the ocean when foundations are removed6.
Removing rigs is also a formidable logistical challenge, because of their size. The topside of a platform, which is home to the facilities for oil or gas production, can weigh more than 40,000 tonnes. And the underwater substructure — the platform’s foundation and the surrounding fuel-storage facilities — can be even heavier. In the North Sea, substructures are typically made of concrete to withstand the harsh environmental conditions, and can displace more than one million tonnes of water. In regions such as the Gulf of Mexico, where conditions are less extreme, substructures can be lighter, built from steel tubes. But they can still weigh more than 45,000 tonnes, and are anchored to the sea floor using two-metre-wide concrete pilings.
Huge forces are required to break these massive structures free from the ocean floor. Some specialists even suggest that the removal of the heaviest platforms is currently technically impossible.
And the costs are astronomical. The cost to decommission and remove all oil and gas infrastructure from UK territorial waters alone is estimated at £40 billion (US$51 billion). A conservative estimate suggests that the global decommissioning cost for all existing oil and gas infrastructure could be several trillion dollars.
Mixed evidence for reefing
In the United States, attitudes to decommissioning are different. A common approach is to remove the topside, then abandon part or all of the substructure in such a way that it doesn’t pose a hazard to marine vessels. The abandoned structures can be used for water sports such as diving and recreational fishing.
This approach, known as ‘rigs-to-reefs’, was first pioneered in the Gulf of Mexico in the 1980s. Since its launch, the programme has repurposed around 600 rigs (10% of all the platforms built in the Gulf), and has been adopted in Brunei, Malaysia and Thailand.
How to stop cities and companies causing planetary harm
Converting offshore platforms into artificial reefs is reported to produce almost seven times less air-polluting emissions than complete rig removal7, and to cost 50% less. Because the structures provide habitats for marine life5, proponents argue that rigs increase the biomass in the ocean8. In the Gulf of California, for instance, increases in the number of fish, such as endangered cowcod (Sebasteslevis) and other commercially valuable rockfish, have been reported in the waters around oil platforms6.
But there is limited evidence that these underwater structures actually increase biomass9. Opponents argue that the platforms simply attract fish from elsewhere10 and leave harmful chemicals in the ocean11. And because the hard surface of rigs is different from the soft sediments of the sea floor, such structures attract species that would not normally live in the area, which can destabilize marine ecosystems12.
Evidence from experts
With little consensus about whether complete removal, reefing or another strategy is the best option for decommissioning these structures, policies cannot evolve. More empirical evidence about the environmental and societal costs and benefits of the various options is needed.
To begin to address this gap, we gathered the opinions of 39 academic and government specialists in the field across 4 continents13,14. We asked how 12 decommissioning options, ranging from the complete removal of single structures to the abandonment of all structures, might impact marine life and contribute to international high-level environmental targets. To supplement the scant scientific evidence available, our panel of specialists used local knowledge, professional expertise and industry data.
The substructures of oil rigs can provide habitats for a wealth of marine life.Credit: Brent Durand/Getty
The panel assessed the pressures that structures exert on their environment — factors such as chemical contamination and change in food availability for marine life — and how those pressures affect marine ecosystems, for instance by altering biodiversity, animal behaviour or pollution levels. Nearly all pressures exerted by leaving rigs in place were considered bad for the environment. But some rigs produced effects that were considered beneficial for humans — creating habitats for commercially valuable species, for instance. Nonetheless, most of the panel preferred, on balance, to see infrastructure that has come to the end of its life be removed from the oceans.
But the panel also found that abandoning or reefing structures was the best way to help governments meet 37 global environmental targets listed in 3 international treaties. This might seem counter-intuitive, but many of the environmental targets are written from a ‘what does the environment do for humans’ perspective, rather than being focused on the environment alone.
Importantly, the panel noted that not all ecosystems respond in the same way to the presence of rig infrastructure. The changes to marine life caused by leaving rigs intact in the North Sea will differ from those brought about by abandoning rigs off the coast of Thailand. Whether these changes are beneficial enough to warrant alternatives to removal depends on the priorities of stakeholders in the region — the desire to protect cowcod is a strong priority in the United States, for instance, whereas in the North Sea, a more important consideration is ensuring access to fishing grounds. Therefore, rig decommissioning should be undertaken on a local, case-by-case basis, rather than using a one-size-fits-all approach.
Legal hurdles in the northeast Atlantic
If governments are to consider a range of decommissioning options in the northeast Atlantic, policy change is needed.
Current legislation is multi-layered. At the global level, the United Nations Convention on the Law of the Sea (UNCLOS; 1982) states that no unused structures can present navigational hazards or cause damage to flora and fauna. Thus, reefing is allowed.
Satellite images reveal untracked human activity on the oceans
But the northeast Atlantic is subject to stricter rules, under the OSPAR Convention. Named after its original conventions in Oslo and Paris, OSPAR is a legally binding agreement between 15 governments and the European Union on how best to protect marine life in the region (see go.nature.com/3stx7gj) that was signed in the face of public opposition to sinking Brent Spar. The convention includes Decision 98/3, which stipulates complete removal of oil and gas infrastructure as the default legal position, returning the sea floor to its original state. This legislation is designed to stop the offshore energy industry from dumping installations on mass.
Under OSPAR Decision 98/3, leaving rigs as reefs is prohibited. Exceptions to complete removal (derogations) are occasionally allowed, but only if there are exceptional concerns related to safety, environmental or societal harms, cost or technical feasibility. Of the 170 structures that have been decommissioned in the northeast Atlantic so far, just 10 have been granted derogations. In those cases, the concrete foundations of the platforms have been left in place, but the top part of the substructures removed.
Enable local decision-making
The flexibility of UNCLOS is a more pragmatic approach to decommissioning than the stringent removal policy stipulated by OSPAR.
We propose that although the OSPAR Decision 98/3 baseline position should remain the same — complete removal as the default — the derogation process should change to allow alternative options such as reefing, if a net benefit to the environment and society can be achieved. Whereas currently there must be an outstanding reason to approve a derogation under OSPAR, the new process would allow smaller benefits and harms to be weighed up.
The burden should be placed on industry officials to demonstrate clearly why an alternative to complete removal should be considered not as littering, but as contributing to the conservation of marine ecosystems on the basis of the best available scientific evidence. The same framework that we used to study global-scale evidence in our specialist elicitation can be used to gather and assess local evidence for the pros and cons of each decommissioning option. Expert panels should comprise not only scientists, but also members with legal, environmental, societal, cultural and economic perspectives. Regions outside the northeast Atlantic should follow the same rigorous assessment process, regardless of whether they are already legally allowed to consider alternative options.
For successful change, governments and legislators must consider two key factors.
Get buy-in from stakeholders
OSPAR’s 16 signatories are responsible for changing its legislation but it will be essential that the more flexible approach gets approval from OSPAR’s 22 intergovernmental and 39 non-governmental observer organizations. These observers, which include Greenpeace, actively contribute to OSPAR’s work and policy development, and help to implement its convention. Public opinion in turn will be shaped by non-governmental organizations15 — Greenpeace was instrumental in raising public awareness about the plan to sink Brent Spar in the North Sea, for instance.
EU climate policy is dangerously reliant on untested carbon-capture technology
Transparency about the decision-making process will be key to building confidence among sceptical observers. Oil and gas companies must maintain an open dialogue with relevant government bodies about plans for decommissioning. In turn, governments must clarify what standards they will require to consider an alternative to removal. This includes specifying what scientific evidence should be collated, and by whom. All evidence about the pros and cons of each decommissioning option should be made readily available to all.
Oil and gas companies should identify and involve a wide cross-section of stakeholders in decision-making from the earliest stages of planning. This includes regulators, statutory consultees, trade unions, non-governmental organizations, business groups, local councils and community groups and academics, to ensure that diverse views are considered.
Conflict between stakeholders, as occurred with Brent Spar, should be anticipated. But this can be overcome through frameworks similar to those between trade unions and employers that help to establish dialogue between the parties15.
The same principle of transparency should also be applied to other regions. If rigorous local assessment reveals reefing not to be a good option for some rigs in the Gulf of Mexico, for instance, it will be important to get stakeholder buy-in for a change from the status quo.
Future-proof designs
OSPAR and UNCLOS legislation applies not only to oil and gas platforms but also to renewable-energy infrastructure. To avoid a repeat of the challenges that are currently being faced by the oil and gas industry, decommissioning strategies for renewables must be established before they are built, not as an afterthought. Structures must be designed to be easily removed in an inexpensive way. Offshore renewable-energy infrastructure should put fewer pressures on the environment and society — for instance by being designed so that it can be recycled, reused or repurposed.
If developers fail to design infrastructure that can be removed in an environmentally sound and cost-effective way, governments should require companies to ensure that their structures provide added environmental and societal benefits. This could be achieved retrospectively for existing infrastructure, taking inspiration from biodiversity-boosting panels that can be fitted to the side of concrete coastal defences to create marine habitats (see go.nature.com/3v99bsb).
Governments should also require the energy industry to invest in research and development of greener designs. On land, constraints are now being placed on building developments to protect biodiversity — bricks that provide habitats for bees must be part of new buildings in Brighton, UK, for instance (see go.nature.com/3pcnfua). Structures in the sea should not be treated differently.
If it is designed properly, the marine infrastructure that is needed as the world moves towards renewable energy could benefit the environment — both during and after its operational life. Without this investment, the world could find itself facing a decommissioning crisis once again, as the infrastructure for renewables ages.
