Ahead of the 250th anniversary of the Declaration of Independence in the US, an ozone nanobubble system has been used to keep the Lincoln Memorial Reflecting Pool clear.

Months before the celebrations a massive clean up of the pool had taken place, but despite this an algae bloom had turned the water bright green. To deal with this a US$1.7 million (£1.27 million) ozone “nanobubbler” injected microscopic bubbles into the pool.

Nanobubbles are extremely small gas bubbles, often made with oxygen, air or ozone, that can remain in water far longer than ordinary bubbles. In a pool, ozone nanobubbles can act as a strong oxidising treatment, attacking algae and organic matter.

But the more important question is whether this state-of-the-art technology can help solve one of the hardest problems in aquatic restoration: getting oxygen to places where lakes, reservoirs and coastal seas are dying from the bottom up.

Clearing the Lincoln Memorial reflecting pool

The famous Lincoln Memorial reflecting pool in Washington DC is shallow, hard bottomed and man-made. It has no natural sediment bed like that of a natural lake, and its primary goal is to look clear. In this context, ozone nanobubbles can be useful, provided the water is circulated artificially and the treatment is maintained.

This is much easier than restoring a natural body of water, where the main problem is often not obvious, and can be complex to resolve.

In a eutrophic lake or sea, one that has become overloaded with nutrients such as phosphorus and nitrogen, algal blooms are a visible symptom of a wider problem. When algae die, they sink. Bacteria decompose organic matter and consume oxygen. The water at the bottom of the lake can become hypoxic (oxygen-poor) or anoxic (essentially oxygen-free). Under these conditions, sediment can release nutrients, and the nutrients can cause eutrophication.

The worst syndrome of this is algal bloom, which can kill fish and create dead zones within the lake. A vicious circle develops: blooms deplete oxygen, oxygen depletion releases nutrients, and nutrients create more blooms.

This is why oxygen delivery is so important. The challenge is not simply to add oxygen somewhere in the lake or sea. It is to deliver oxygen precisely to the thin layer of bottom sediment, where phosphorus is released, methane produced, and other processes occur.

So, there are two types of nanobubble use.

The first is bulk nanobubbles: bubbles dispersed through the water by machines. These can work well in tanks, aquaculture systems, wastewater treatment, pools and small bodies of water which can be continuously circulated.

But in large natural waters, bulk treatment faces practical limitations. The machines must keep running, and the oxygen distribution depends on pumps, cables and pipes. In a large lake or sea basin, that means high energy demand and uncertain delivery to the bottom.

The second type is what are called interfacial oxygen nanobubbles. These are oxygen nanobubbles attached to the surfaces and pores of solid particles, such as modified clay or other porous natural materials. Oxygen is loaded onto particles that sink. The particles then deliver oxygen directly to the area where the water meets the sediment.

This could reduce energy requirements and avoid some of the ecosystem disturbance associated with large-scale artificial mixing.

The potential impact is significant. If oxygen can be delivered cost-effectively to surface sediments, it may help reduce internal phosphorus release, suppress methane generation, and generally make conditions more favourable for life at the bottom of ocean. These go to the heart of whether a degraded lake or coastal basin can recover.

This is a very different engineering idea. It does not aim to oxygenate the entire volume of the lake.

However, if sewage or fertiliser runoff continue, any oxygenation technology will not be effective.

This strategy for lake restoration is to remove algae and nutrients from the water, lock nutrients into the seabed sediments, and oxygenate the sediment surface to reduce nutrients re-release.

Baltic Sea project

The importance of this targeted approach becomes clearer when we look at the Baltic Sea, one of the world’s best-known examples of oxygen-depleted “dead zones”.

The Baltic is naturally vulnerable due to limited water coming in and out of the sea as it connects through very narrow waterways. It also has distinct deep water and surface layers that don’t tend to mix. Nutrients are constantly released from the sediment into the water, causing oxygen levels to drop dramatically.

One of the most ambitious engineering responses to tackle this kind of dying sea was the deep-water oxygenation project in the Baltic. The principle was straightforward: pump oxygen-rich surface or upper-layer water down into deep oxygen-depleted water.

This process used wind-powered pumping to move oxygen-enriched water from around 50 metres down to much deeper, about 125 metres, using around 100 offshore wind-powered pumps. An alternative to the process used in the Baltic project would be to use nanobubble-clay materials to deliver oxygen onto the deep water sea bottom by gravity and reduce the energy cost and negative impact to the aquatic ecosystem.

The project, which began work in 2009, showed why fixing the problem is so difficult.

Pumping can increase oxygen levels, but it requires extensive infrastructure and can alter the hydrology and ecology of the whole lake or sea. There are unresolved questions about cost, energy, maintenance, ecological side effects and other environmental effects.

In a shallow hard-bottom pool, nanobubbles are judged by whether the water looks clear. Oxygen nanobubbles attached to porous particles could become a lake or sea restoration tool, but with limitations.

Nanobubbles greatest environmental value may be in helping oxygen reach the dark, thin, neglected layer, the dead zone, at the bottom of lakes and seas. But this may be a costly, and complicated, exercise.

Gang Pan does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

Growing evidence suggests that excessive outdoor lighting at night may be harming wildlife.

For generations, rural communities worked to the rhythms of daylight and darkness. Today, the amount of harsh light switched on at nightime is having profound consequences for many living things.

Agricultural properties are often remote and vulnerable to equipment or livestock theft. In response, many landowners have now installed security floodlights, powerful halogen beams, and unshielded external LEDs to illuminate yards overnight.

The North York Moors National Park, an international dark sky reserve in the north of England, has been working with farmers to reduce the impact of artificial light on the natural environment.

The initiative is about ensuring that lighting is used in the right place, at the right time, and at the appropriate intensity. This might involve installing downward-facing fixtures, reducing glare through shielding, or switching to warmer-coloured lighting that is less disruptive to wildlife.

The best places to start trying to reduce bright nighttime lights are those rich in wildlife, and farms in the park are often in the darkest areas.

Since 2021, the national park has worked with more than twenty farms in key dark sky locations, with many more projects in development.

Carefully designed lighting systems can use shielded or motion-activated lighting, which reduce impact on wildlife.

How does it affect the environment?

Over-illumination disrupts complex regional ecosystems, extending daylight artificially and changing the behaviour of animals that depend on natural darkness. Research suggests that light pollution caused by humans, harms ecosystems because of the critical role light has on the timing of biological systems, which artificial light disrupts.

---

Read more: Why walking in a national park in the dark prompts people to turn off lights at home

---

The damage extends from the soil upward. Scientific research indicates that pressures on ecosystems due to habitat loss, pesticides, invasive species and light pollution could create a devastating decline in the insect population, with a knock-on effect on the food chain.

Benefits for farms?

There’s also evidence that suggests that changing lighting could help farms. This light disruption affects crucial agricultural allies. Moths, which serve as vital nocturnal pollinators, are heavily affected, alongside bats facing shrinking feeding grounds. Bats can help farmers control insect pests.

Artificial light exposure also alters vital plant cycles, for instance, and light at night can affect plant growth.

Small changes, such as switching to down-facing lights, can lead to significant environmental improvements.

Changing lighting around farms could also open up new tourism opportunities. Farms that also operate as B&Bs, for instance, can flag to tourists that they are part of a dark skies friendly community programme. This is an accreditation scheme for businesses that improve their lighting systems in accordance with international dark sky standards.

While UK national park authorities have powers to enforce planning restrictions on lighting, in places outside national parks, the UK lacks a comprehensive national regulatory framework to govern rural skyscapes.

The lesson in North Yorkshire and beyond is not that farms should switch off their lights. It is that lighting can be used responsibly to contribute to the stewardship of one of the countryside’s most valuable resources: the natural night sky.

The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.

In the first landmark publication of his papacy, Pope Leo XIV has addressed recent advances in artificial intelligence by focusing on the threat it poses to workers, social justice and “the dignity of persons”.

Presenting his first papal encyclical, “Magnifica Humanitas” (“Magnificent Humanity”), at the Vatican on May 25, Leo declared: “Artificial intelligence needs to be disarmed.”

In the document – comprising around 42,300 words in its English translation – the pope writes: “To disarm does not mean rejecting technology, but preventing it from dominating humanity.”

Encyclicals are exceptionally important papal documents that respond to the most pressing social issues of the time. Typically written as letters to all bishops and archbishops, they have become a crucial vehicle for disseminating the theology and political commitments of the Roman Catholic Church across the world.

Leo chose to sign his first encyclical on May 15 2026, the exact anniversary of Pope Leo XIII’s “Rerum novarum” (“Of new things”). This famous encyclical, which responded to the technological advances of the industrial revolution, became the foundational document of all modern Catholic social teaching.

Indeed, the current pope probably chose the name Leo because of Leo XIII’s renowned commitment to social justice.

Just as “Rerum novarum” responded to the industrial revolution by emphasising workers’ rights and the dignity of human labour, so too Leo XIV has responded to the explosion of AI technology by emphasising the importance of human over machine intelligence.

In 1891, Leo XIII wrote: “Wage-earners … should be specially cared for and protected by the government.”

Leo XIV now makes similar appeals to world governments about AI: “It is necessary to establish adequate regulatory tools capable of upholding justice and curbing the distorting effects of technological power.”

The current pope follows a long tradition of Catholic engagement with new tech – from concerns about the impact of the printing press in the 15th century to the rise of the internet over 500 years later.

Leo XIV’s presentation was preceded by a short film which juxtaposed images of previous popes with major technological innovations. Radio towers gave way to images of broadband centres; early computers to a sea of people holding up their smartphones in St Peter’s Square, Vatican City.

Perhaps the crucial theme of this video was the connection between technology and war. Pictures of second world war aircraft were intercut with the dropping of the atomic bomb, soon followed by images of the 9/11 attacks.

In the encyclical, Leo warns: “The growing ease with which autonomous weapons systems can be deployed makes war more ‘feasible’ and less subject to human control.”

Call for disarmament

Leo XIV isn’t the first pope to address the potential threat posed by AI technology. In January 2025, his predecessor Francis signed off the doctrinal note “Antiqua et nova” (“Ancient and new”) – which called for AI technology “to include the least of our brothers and sisters, the vulnerable and those most in need”.

Leo’s new call for the disarmament of AI is not a demand to discontinue its development, but to regulate AI robustly so it only serves the common good.

In this, the pope drew an analogy with the nuclear disarmament movement, suggesting that both nuclear and AI technologies should only be developed for the good of humanity, and never used as weapons.

Those invited to offer their thoughts on Leo’s encyclical included Christopher Olah, the Canadian billionaire and co-founder of AI firm Anthropic. The appearance of Olah marks the first time a speaker entirely outside clerical or theological circles has been included in such a presentation.

Anthropic is currently locked in a legal dispute with the US government regarding the military application of its AI systems. Leo’s encyclical underlines his concerns about the escalation of war around the world, stating: “It is important to reaffirm that the ‘just war’ theory, which has all too often been used to justify any kind of war, is now outdated.”

Olah echoed Leo’s demands for greater social justice around the use of AI, stating: “His Holiness’s call for disarmament is profoundly timely.”

He called for people working outside computer science to contribute to AI governance and ethics – people “beyond the incentives” of financial markets “who can see what we, from the inside, cannot”.

Leo answered Olah by saying: “In the name of the Church, I accept your invitation to walk together, to listen and to speak – and together, to find the way for humanity in this time of artificial intelligence.”

James Lorenz does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.