The UK’s largest freshwater lake experienced its worst-ever levels of a harmful bacteria this summer.
Lough Neagh – a lake in Northern Ireland that is larger than the country of Malta – has been plagued by blue-green algae that can negatively impact humans, plants and animals.
A group of environmentalists recently held a “wake” to protest the scale of the situation.
Scientists tell Carbon Brief that agricultural nutrient runoff and climate change are the main roots of the problem – and that there is no “silver-bullet” solution.
In this article, Carbon Brief explains what happened on Lough Neagh this summer, how climate change made the situation worse and how it is being tackled without a functioning devolved government in place.
- What happened on Lough Neagh?
- What role does climate change have in the algal blooms?
- What is being done to improve the situation?
What happened on Lough Neagh?
Lough Neagh is the largest freshwater lake in the UK and Ireland, spanning around 380 square kilometres (km2). It holds more than 800bn gallons of water and stretches across five of the six counties in Northern Ireland.
The lake hosts a range of plant and animal species, including whooper swans, tufted ducks and the rare Irish Lady’s Tresses orchid. The wider 5,400km2 basin around the lake holds wildlife-rich wetlands.
The map below shows the scale of Lough Neagh compared to the rest of Northern Ireland.
Since May, high levels of a type of bacteria called blue-green algae have been identified in a number of rivers, lakes and coastlines in Northern Ireland. Lough Neagh has been particularly impacted.
These cyanobacteria – a type of bacteria that can photosynthesise – naturally inhabit freshwater ecosystems.
But if they get plenty of sunlight, CO2 and nutrients – such as nitrogen and phosphorus – they can grow in big numbers and begin to form visible algal “blooms”. The blooms negatively impact the appearance, quality and use of the water.
The recent blooms have affected swimmers and fisheries in Lough Neagh, which contains Europe’s largest commercial wild eel fishery.
It can cause rashes and illnesses in humans and can “potentially kill wild animals, livestock and pets if ingested”, according to the Northern Ireland Department of Agriculture, Environment and Rural Affairs (Daera).
The blooms also block sunlight from reaching other plants and use up oxygen in the water, which can suffocate fish and other creatures.
The image below shows the blooms visible from Copernicus satellite imagery on 4 September. The green swirls of algae are particularly noticeable on the eastern side of the lake.
Lough Neagh supplies around 40% of all drinking water in Northern Ireland. NI Water says that drinking water drawn from the lake remains “safe to drink and use as normal”.
The issue has had a political impact in Northern Ireland, where the devolved government has been at a standstill since last year due to Brexit-related issues.
The climate-sceptic former Northern Ireland environment and agriculture minister, Edwin Poots, said the blooms are a “very significant issue”.
What role does climate change have in the algal blooms?
There are a number of drivers behind the increase in algal blooms on Lough Neagh this summer.
This includes excess nutrient runoff from agricultural and wastewater systems, “combined with climate change and the associated weather patterns, such as the exceptionally warm June, followed by the wet July and August”, Daera says in a statement to Carbon Brief. The department adds:
“This is a complex, multi-factorial issue that will take years, if not decades, to solve.”
Studies say that excessive nutrients are the main cause of blue-green algal blooms in freshwater lakes around the world. Nitrogen and phosphorus occur naturally in water, but agricultural fertilisers, sewage run-off, household products and storm water flows can cause an overabundance of these nutrients
Algal blooms appear as a result of eutrophication – a process arising from too many nutrients in the water boosting the growth of plants and algae.
Lough Neagh is “hypereutrophic”, meaning it is especially rich in nutrients coming from a range of sources.
Prof Mark Emmerson, a professor of biodiversity at Queen’s University Belfast, says the nutrient issue is heightened further by climate change. He tells Carbon Brief:
“We’ve had the wettest July on record. The consequence of that is that when we have farmers who are managing their slurry [mixture of animal waste and water used as fertiliser]…climate events are leading to that being washed out into our river courses and down into the Lough.
“You get this combination of multiple stressors that erode the capacity of an ecosystem like Lough Neagh to absorb and recover from these sorts of events.”
The UK and Ireland have experienced more rainfall on average in recent decades. This trend is predicted to continue as global temperatures rise further, according to the Intergovernmental Panel on Climate Change.
The map below shows rainfall levels across the UK in July this year compared to the 30-year average. The dark purple areas experienced the highest above-average rainfall levels. Northern Ireland (left) saw more than double its average rainfall for the month.
Rising temperatures also play a role in the growth of blue-green algae, according to Prof Christopher Gobler, endowed chair of coastal ecology and conservation at Stony Brook University in New York. He tells Carbon Brief that the climate impact on blooms is a “no-doubter”:
“If you go back even to the 20th century, the summers just weren’t as warm as they are today. The warming sets up a whole multitude of effects. These blue-green algae, they grow best at really high temperatures. The warmer it gets in general, the better they do.”
A 2011 study found that nutrient levels and climate change “synergistically enhance” cyanobacteria blooms in bodies of water.
However, other research published earlier this year found that nutrients were the main reason behind cyanobacteria growth in lakes in the Americas.
The researchers found “no clear trends” in the links between algal blooms and latitude. Water temperature is “only weakly” related to bloom growth, the study said, saying this aspect has been “overemphasised” previously.
A greater focus on reducing nutrients would improve the situation for lakes such as Lough Neagh, Gobler tells Carbon Brief:
“If you can address the nutrient issue, what that says is that you can actually overcome the temperature issue…In the 20th century, [the] nutrients may have been there, but because the window of opportunity of temperature was short, you didn’t get the blooms.
“But now, since the window is open for most of the summer and the nutrient levels are high – now you’re getting the blooms.”
Other issues have affected this year’s blooms on Lough Neagh. The lake has a high population of zebra mussels, an invasive species, which Daera says upset the “ecological balance” in the Lough.
The filter feeding of the zebra mussels may have contributed to making the water clearer, allowing more sunlight to pass through and boost bloom growth – as well as removing food for native species.
A 2008 study found that harmful blooms in freshwater ecosystems “may lead to mass mortalities of fish and birds” and pose a health threat to cattle, pets and humans. The study, based on modelling, found that high temperatures cause increased growth rates of cyanobacteria and that summer heatwaves “boost the development” of toxic blooms.
The wider impacts on Lough Neagh specifically “remain very much unknown”, Emmerson tells Carbon Brief. He adds:
“We don’t know what the impact on the fish communities that are commercially harvested will have been. We also don’t know what the impacts [are] on the invertebrates that live on the rocks on the bottom of the lake…which are also important food for the fish communities that live there.”
What is being done to improve the situation?
The situation on Lough Neagh is ongoing, but the blooms have started to decline. Daera tells Carbon Brief in a statement:
“Whilst the reporting of visible blooms has decreased and there is evidence that the blue-green algae is starting to break down, the situation of the blooms in Lough Neagh are still being closely monitored, but it is anticipated that as temperatures drop and daylight shortens, the blooms will subside.”
Algal blooms can occur at any time of year and often do on Lough Neagh, but they are most commonly found between May and September.
Daera says it “recognises the seriousness of the situation” this summer and the department continues to assess water quality on the lake.
A team was set up to focus on the immediate response to the situation and a panel of experts will develop recommendations to improve water quality in Northern Ireland, the department says.
Daera adds that any reviews and recommendations for action will be considered in the context of other public-sector demands and also within the “priorities of a returning executive”, referring to the Northern Ireland government which collapsed in May 2022.
The situation on Lough Neagh “vividly illustrates years of political failure – no legislation to protect the environment and no government to address the crisis”, Sky News senior Ireland correspondent David Blevins wrote last month.
The executive has been in a state of collapse for more than 40% of its existence. Northern Ireland’s lawmaking assembly also collapsed in October 2022 over disagreements on post-Brexit trade rules.
Since last year, civil servants have managed government responsibilities. But they are not able to develop new policies or make political decisions, leaving Northern Ireland at a political standstill.
In the past, the UK government has imposed “direct rule” where they took over responsibility for Northern Ireland government decisions during times of collapse. But this has not been implemented since 2007.
The Social Democratic and Labour party last month launched a motion to recall the Northern Ireland assembly to discuss the “ecological crisis” on Lough Neagh, according to BBC News.
Emmerson believes that “nothing is going to happen” in the absence of a functioning devolved government. He tells Carbon Brief:
“I’m confident that we have the technologies, the engineering solutions, the nature-based solutions [and] the capacity to develop social solutions that could work, but whether the political will is there or not, I’m not quite sure – even if we had a functioning government.”
There’s no “silver-bullet” solution to the situation, Emmerson adds, but actions such as planting trees on upland areas to reduce seepage from land to water and reducing fertiliser use on farms would have multiple benefits. He says:
“Many of the solutions which are aimed at improving water quality and addressing the solution in somewhere like Lough Neagh have indirect co-benefits for climate-related action and for nature recovery all at the same time.
“There’s this lack of recognition that the climate and biodiversity and water-quality crises are all interlinked. If you put in place mitigating measures for one, then you are likely to have beneficial effects – what we call co-benefits – for many of the other large-scale crises that we are facing at the moment.”
James Orr, director of Friends of the Earth Northern Ireland, says that although the blooms have receded, the lack of concrete action is “condemning Lough Neagh to more ecological catastrophe in the future”. He tells Carbon Brief:
“That’s the most depressing issue, that we’ve basically condemned these problems to happen repeatedly in the future with much greater severity because they [the government] will do anything other than tackle the sources of pollution – be it human sewage or animal waste.”
Orr says that taking Lough Neagh into public ownership would be one good step to tackle the situation. The bed and soil of Lough Neagh is currently owned by the Earl of Shaftesbury’s estate.
A petition to bring the lough into public ownership and manage it under a single body was submitted to the UK parliament last month. This was rejected.
Nicholas Ashley-Cooper, who currently holds the title of Earl of Shaftesbury, told BBC News that he is willing to sell the lake to the public – “but won’t give it away for free”.
Orr says that if a functioning devolved government had been in place in recent months, there could have been closer scrutiny of politicians, civil servants and the bodies responsible for protecting the environment. But, he adds:
“The system has just got its hands over its ears…[This is] going to happen again and again and again, and it’s going to happen for decades unless we do the obvious thing – reduce the pollution and invest in sewage infrastructure.”
The post Lough Neagh: How climate change intensified toxic algae on the UK’s largest lake appeared first on Carbon Brief.
Lough Neagh: How climate change intensified toxic algae on the UK’s largest lake
The launch of the Africa Energy Bank (AEB) has been put back yet again, raising doubts about the institution’s future ability to finance fossil fuel projects – its main objective – as global lenders retreat from such investments over climate concerns, experts told Climate Home News.
The bank, which had been billed to launch in September after a series of delays, is now scheduled to begin operations in November, according to the head of the African Energy Chamber, an advocacy body for the continent’s oil and gas sector.
Even as the world aims to transition away from fossil fuels, many African leaders have made clear they want to continue exploring and extracting the continent’s large oil and gas deposits – estimated at around 125 billion barrels of crude and over 600 trillion cubic feet of gas – to boost economic development.
As a group, Africa sided with a number of powerful oil-and-gas producing nations in blocking progress on negotiations to craft a global roadmap to transition away from fossil fuels at last year’s UN COP30 climate talks, although some countries did individually support the proposal.
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Meanwhile, major projects under development across the continent – including the 1,443-km East African Crude Oil Pipeline (EACOP) and Dangote’s 700,000-barrel-per-day Kenyan refinery – show that African governments see oil and gas as playing a significant role in meeting their energy and economic needs for many years to come.
In 2022, at a gathering of the African Petroleum Producers’ Organization (APPO) in oil-rich Angola, ministers from its member states adopted a resolution to create the Africa Energy Bank to finance projects for the production, use and trade of oil, gas and broader energy sources.
African control over energy resources
An article on the APPO website explains that the bank was conceived as a way to overcome “disenchantment” with fossil fuels among “the international community” which it said had crystallised around the “energy transition” concept.
“If Western countries, after having long taken advantage of the energy sources they now revile to develop, can afford the luxury of abandoning them, this is not the case in Africa,” it adds, noting that many of the continent’s economies are still largely dependent on oil and gas revenues.
A separate web page about the bank, also hosted on APPO’s website, says its objectives include financing the exploration, production and refining of oil and gas, as well as supporting member states in transitioning from fossil fuels to cleaner energy sources “while ensuring energy security”.
Said Addi, a former executive with Shell and energy commodities trading house Gunvor, said the new bank was judged necessary because financing for hydrocarbons from many traditional international lenders has become constrained.
In trying to fill this financing gap, Africa is not simply setting up another fund to support oil and gas, he added. “It is also an attempt to give African countries greater control over how their energy resources and infrastructure are financed,” he explained.
Nigeria to host the AEB
The energy bank – a joint initiative of APPO and the African Export–Import Bank (Afreximbank) – has so far suffered several delays and is almost two years behind schedule. The initial plan was to start operations in January 2025, with Nigeria as the host country, but the bank’s opening was delayed to June of that year to allow Nigeria time to finalise the construction of the bank’s headquarters in Abuja.
After the government announced the completion of the offices in late November 2025, a new launch date was set for January 2026, which was moved back to April, June and then September. Now it has shifted again to November, raising concerns that the institution may be losing momentum.
Former Shell executive Addi said that if the capital is eventually paid in, the bank becomes operational and its first projects are commercially credible, then the delays will be regarded as normal teething troubles in setting up a multilateral institution. But, he added, scepticism will be justified if it continues to stall.
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Baron Lamarré, an oil and gas expert and former Petronas oil trader, said that missing “three deadlines in a row is not normal”, and warned that if the timeline slips again, “the story flips from ‘ambitious institution finding its footing’ to ‘good idea that lost momentum before it found any’.”
The Nigerian government, APPO and Afreximbank did not respond to requests for comment by the time of publication.
The funding challenge
The Africa Energy Bank is targeting base capital of $5 billion, with plans to scale up to $120 billion within five years by mobilising private-sector funds. However, it is expected to start operations with initial seed capital of $500 million.
The funding plan is to have the 18 member countries of the APPO contribute $83 million each to the bank as equity for a combined $1.5 billion. Afreximbank, other non-APPO African countries and investors outside the continent are expected to provide the remaining $3.5 billion.
But even the initial $500 million has not been easy to mobilise. In May, APPO Secretary-General Farid Ghezali called on members to deliver on their pledges towards the startup goal before the end of June. But the delays suggest this may not have been met, with experts saying Africa may be finding it difficult to self-fund its oil and gas projects in the absence of international capital.
Lamarré said every extension of the deadline points to the fact that “raising fossil fuel capital in Africa without the majors and their financing networks is brutally hard”.
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Since 2020, Western lenders, export credit agencies and insurers have been in steady retreat from African hydrocarbons, he said, while oil majors are divesting their African assets, handing over fields to smaller local operators whose credit ratings are not high enough to borrow cheaply.
Even capital from China and the Gulf, which has partially filled the gap, cannot match the volume, tenor or pricing that Western investors once offered, Lamarré argued.
“If mobilising the first $500 million of seed capital [for the AEB] has taken this long, that’s the clearest signal yet of how steep the climb to $120 billion looks,” he said, noting that the continent’s energy financing gap is as large as $30 billion-$45 billion per year.
Africa’s investment landscape, meanwhile, has been shifting. While foreign direct investment dropped from a 2024 peak, inflows remained roughly one-third above the continent’s long-term average in 2025, according to the 2026 World Investment Report from UN Trade and Development (UNCTAD). They are concentrated in a few sectors including critical minerals needed for renewable energy technologies, battery manufacturing and advanced industrial production.
At the same time, data on global