At 12.33pm on Monday 28 April, most of Spain and Portugal were plunged into chaos by a blackout.
While the initial trigger remains uncertain, the nationwide blackouts took place after around 15 gigawatts (GW) of electricity generating capacity – equivalent to 60% of Spain’s power demand at the time – dropped off the system within the space of five seconds.
The blackouts left millions of people without power, with trains, traffic lights, ATMs, phone connections and internet access failing across the Iberian peninsula.
By Tuesday morning, almost all electricity supplies across Spain and Portugal had been restored, but questions about the root cause remained.
Many media outlets were quick to – despite very little available data or information – blame renewables, net-zero or the energy transition for the blackout, even if only by association, by highlighting the key role solar power plays in the region’s electricity mix.
Below, Carbon Brief examines what is known about the Spanish and Portuguese power cuts, the role of renewables and how the media has responded.
What happened and what was the impact?
The near-total power outage in the Iberian Peninsula on Monday affected millions of people.
Spain and Portugal experienced the most extensive blackouts, but Andorra also reported outages, as did the Basque region of France. According to Reuters, the blackout was the biggest in Europe’s history.
Shortly after 12.30pm, the grid suffered an “event” akin to loss of power generation, according to a summary of the call posted by Bloomberg’s energy and commodities columnist Javier Blas on LinkedIn. While the grid almost immediately self-stabilised and recovered, about 1.5 seconds later a second “event” hit, he wrote.
Around 3.5 seconds later, the interconnector between the Spanish region of Catalonia and south-west France was disconnected due to grid instability. Immediately after this, there was a “massive” loss of power on the system, Blas said.
This caused the power grid to “cascade down into collapse”, causing the “unexplained disappearance” of 60% of Spain’s generation, according to Politico.
It quoted Spanish prime minister Pedro Sánchez, who told a press conference late on Monday that the causes were not yet known:
“This has never happened before. And what caused it is something that the experts have not yet established – but they will.”
The figure below shows the sudden loss of 15GW of generating capacity from the Spanish grid at 12.33pm on Monday. In addition, a further 5GW disconnected from the Portuguese grid.
Electricity generation capacity in Spain, megawatts (MW), from 27-29 April, showing the drop in generation. Credit: Red Eléctrica.
The Guardian noted in its coverage that “while the system weathered the first event, it could not cope with the second”.
A separate piece from the publication added that “barely a corner of the peninsula, which has a joint population of almost 60 million people, escaped the blackout”.
El País reported that “the power cut…paralysed the normal functioning of infrastructures, telecommunications, roads, train stations, airports, stores and buildings. Hospitals have not been impacted as they are using generators.”
According to Spanish newswire EFE, “hundreds of thousands of people flooded the streets, forced to walk long distances home due to paralysed metro and commuter train services, without mobile apps as telecommunications networks also faltered”.
It added that between 30,000 and 35,000 passengers had to be evacuated from stranded trains.
The New York Times reported that Portuguese banks and schools closed, while ATMs stopped working across the country and Spain. People “crammed into stores to buy food and other essentials as clerks used pen and paper to record cash-only transactions”, it added.
Spain’s interior ministry declared a national emergency, according to Reuters, deploying 30,000 police to keep order.
Both Spain and Portugal convened emergency cabinet meetings, with Spain’s King Felipe VI chairing a national security council meeting on Tuesday to discuss an investigation into the power outage, Sky News reported.
By 10pm on Monday, 421 out of Spain’s 680 substations were back online, meaning that 43% of expected power demand was being met, reported the Guardian.
By Tuesday morning, more than 99% of the total electricity supply had been recovered, according to Politico, quoting Red Eléctrica.
In Portugal, power had been restored to every substation on the country’s grid by 11.30pm on Monday. In a statement released on Tuesday, Portuguese grid operator REN said the grid had been “fully stabilised”.
What caused the power cuts?
In the wake of the power cuts, politicians, industry professionals, media outlets, armchair experts and the wider public scrambled to make sense of what had just happened.
Spanish prime minister Sánchez said on the afternoon of the blackout that the government did not have “conclusive information” on its cause, adding that it “[did] not rule out any hypothesis”, Spanish newspaper Diario Sur reported.
Nevertheless, some early theories were quickly rejected by officials.
Red Eléctrica, “preliminarily ruled out that the blackout was due to a cyberattack, human error or a meteorological or atmospheric phenomenon”, El País reported the day after the event.
Politico noted that “people in the street in Spain and some local politicians” had speculated about a cyberattack.
However, it quoted Eduardo Prieto, Red Eléctrica’s head of system operation services, saying that while the conclusions were preliminary, the operator had “been able to conclude that there has not been any type of intrusion in the electrical network control systems that could have caused the incident”.
The Majorca Daily Bulletin reported that Spain’s High Court said it would open an investigation into whether the event was the result of a cyberattack.
Initial reporting by news agencies blamed the power cuts on a “rare atmospheric phenomenon”, citing the Portuguese grid operator REN, according to the Guardian. The newspaper added that REN later said this statement had been incorrectly attributed to it.
The phenomenon in question was described as an “induced atmospheric vibration”.
Nevertheless, he said the phenomenon being described was familiar, referring to “wavelike movements” in the atmosphere caused by sudden changes in temperature or pressure.
In general terms, Reuters explained that power cuts are often linked to extreme weather, but that the “weather at the time of Monday’s collapse was fair”. It added that faults at power stations, power distribution lines or substations can also trigger outages.
Another theory was that a divergence of electrical frequency from 50 cycles per second (Hz), the European standard, could have caused parts of the system to shut down in order to protect equipment, France 24 explained.
Some analysts noted that “oscillations” in grid frequency shortly before the events in Spain and Portugal could be related to the power cuts. Tobias Burke, policy manager at Energy UK, explained this theory in his Substack:
“The fact these frequency oscillations mirrored those in Latvia…at the other extreme of the Europe-spanning ENTSO-E network, might suggest complex inter-area oscillations across markets could be the culprit.”
This phenomenon can be seen in a chart shared by Prof Lion Hirth, an energy researcher at Hertie School, on LinkedIn.
With many details still unknown, much of the media speculation has focused on the role that renewable energy could have played in the blackouts. (See: Did renewable energy play a role in the cut?)
“There’s a variety of things that usually happen at the same time and it’s very difficult for any event to say ‘this was the root cause’.”
Nevertheless, there are several efforts now underway to determine what the causes were.
Portugal’s prime minister, Luís Montenegro, announced on Tuesday that the government would set up an independent technical commission to investigate the blackouts, while stressing that the problem had originated in Spain, according to Euractiv.
Finally, EU energy commissioner Dan Jørgensen has indicated that the EU will open a “thorough investigation” into the reasons behind the power cuts, BBC News noted.
Did renewable energy play a role in the blackouts?
As commentators began to look into the cause of the blackout, many pointed to the high share of renewables in Spain’s electricity mix.
On 16 April, Spain’s grid had run entirely on renewable sources for a full day for the first time ever, with wind accounting for 46% of total output, solar 27%, hydroelectric 23% and solar thermal and others meeting the rest, according to PV Magazine.
Spain is targeting 81% renewable power by 2030 and 100% by 2050.
At the time of the blackout on Monday, solar accounted for 59% of the country’s electricity supplies, wind nearly 12%, nuclear 11% and gas around 5%, reported the Independent.
The initial “event” is thought to have originated in the south-western region of Extremadura, noted Politico, “which is home to the country’s most powerful nuclear power plant, some of its largest hydroelectric dams and numerous solar farms.”
On Tuesday, Red Eléctrica’s head of system operation services Eduardo Prieta said that it was “very possible that the affected generation [in the initial ‘events’] could be solar”.
This sparked further speculation about how grids that are highly reliant on variable renewables can be managed so as to ensure security of supply.
Political groups such as the far-right VOX – which has historically pushed back against climate action such as the expansion of renewables – also pointed to the blackout as evidence of “the importance of a balanced energy mix”.
However, others rejected this suggestion, with EU energy chief Dan Jørgensen telling Bloomberg that the blackout could not be pinned on a “specific source of energy”:
“As far as we know, there was nothing unusual about the sources of energy supplying electricity to the system yesterday. So the causes of the blackout cannot be reduced to a specific source of energy, for instance renewables.”
Others have sought to highlight that, while it was possible solar power was involved in the initial frequency event, this does not mean that it was ultimately the cause of the blackout.
Writing on LinkedIn, chief technology officer of Arenko, a renewable energy software company, Roger Hollies, noted:
“The initial trip may well have been a solar plant, but trips happen all the time across all asset types. Networks should be designed to withstand multiple loss of generators. 15GW is not one power station, this is the equivalent of 10 large gas or nuclear power stations or 75 solar parks.”
Others pointed to what they said was insufficient nuclear power on the grid – a notion that prime minister Sánchez rejected, according to El País.
Speaking on Tuesday, he said that those arguing the blackouts showed a need for more nuclear power were “either lying or showing ignorance”, according to the newspaper. It said he highlighted that nuclear plants were yet to fully recover from the event.
One key aspect of the transition away from electricity systems built around thermal power stations burning coal, gas or uranium is a loss of “inertia”, the Financial Times highlighted.
Thermal power plants generate electricity using large spinning turbines, which rotate at the same 50 cycles per second (Hz) speed as the electrical grid oscillates. The weight of these “large lump[s] of spinning metal” gives them “inertia”, which counteracts changes in frequency on the rest of the grid.
When faults cause a rise or fall in grid frequency, this inertia helps lower the rate of change of frequency, giving system operators more time to respond, noted Adam Bell, director of policy at Stonehaven, in a post on LinkedIn.
Solar does not include a spinning generator, and therefore, critics pointed to the lack of inertia on the grid due to the high levels of the technology as a cause of the blackout.
As Bell pointed out, this ignores the inertia provided by nuclear, hydro and solar thermal on the grid at the time of the blackout, alongside the Spanish grid operator having built “synchronous condensers” to help boost inertia and grid stability.
Bell added:
“A lack of inertia was therefore not the main driver for the blackout. Indeed, post the frequency event, no fossil generation remained online – but wind, solar and hydro did.”
While the ultimate cause of the blackouts remains to be seen, they have highlighted the need for an increased focus on grid stability, particularly as the economy is electrified.
A selection of comments from experts published in Review Energy emphasises the need for further resilience to be built into the grid as it transitions away from fossil fuels.
How has the media responded to the power cut?
As the crisis was still unfolding and its cause remained unknown, several climate-sceptic right-leaning UK publications clamoured to draw a link between the blackouts and the nations’ reliance on renewable energy.
It comes as right-leaning titles have stepped up their campaigning against climate policy over the past year.
On Tuesday, the Daily Telegraph carried a frontpage story headlined: “Net-zero blamed for blackout chaos.”
But the article contradicted its own headline by concluding: “What exactly happened remains unclear for now. And the real answer is likely to involve several factors, not just one.”
None of the experts quoted in the piece blamed “net-zero” for the incident.
The Daily Telegraph also carried an editorial seeking to argue renewable energy was the cause of the blackouts, which claimed that “over-reliance on renewables means a less resilient grid”.
The Daily Express had an editorial (not online) claiming that the blackout shows “relying on renewables is dim”.
Additionally, the Standard carried a comment by notorious climate-sceptic commentator Ross Clark breathlessly blaming the blackout on “unreliable” renewables, with a fear-monguering warning that the “same could happen in the UK”.
The Daily Mail published a comment by Rupert Darwall, a climate-sceptic author who is part of the CO2 Coalition – an organisation seeking to promote “the important contribution made by carbon dioxide to our lives” – which claimed that the blackout showed “energy security is being sacrificed at the altar of green dogma”.
Climate-sceptic libertarian publication Spiked had a piece by its deputy editor Fraser Myers titled: “Spain’s blackouts are a disaster made by net-zero.” The article claimed that “our elites’ embrace of green ideology has divorced them from reality”.
In Spanish media, Jordi Sevilla, the former president of Red Eléctrica, wrote in the financial publication Cinco Días that, while it is not known what caused the blackout, it is clear that the country’s grid “requires investments to adapt to the technical reality of the new generation mix”. He continued:
“In Spain, in the last decade, there has been a revolution in electricity generation to the point that renewable technologies ([solar] photovoltaic and wind, above all) now occupy the majority of the energy mix. This has had very positive impacts on CO2 emissions, lower electricity prices and increased national autonomy.
“But there is a technical problem: photovoltaic and wind power are not synchronous energies, whereas our transmission and distribution networks are designed to operate only with a minimum voltage in the energy they transport. Therefore, to operate with current technology, the electrical system must maintain synchronous backup power, which can be hydroelectric, gas or nuclear, to be used when photovoltaic and wind power are insufficient, either due to their intermittent nature (there may be no sun or wind) or due to the lack of synchronisation required by the generators to operate.”
For Bloomberg, opinion columnist Javier Blas said that “Spain’s blackout shouldn’t trigger a retreat from renewables”, but shows that “an upgraded grid is urgently needed for the energy transition”. He added:
“The world didn’t walk away from fossil-fuel and nuclear power stations because New York suffered a massive blackout in 1977. And it shouldn’t walk away from solar and wind because Spain and Portugal lost power for a few hours.
“But we should learn that grid design, policy and risk mapping aren’t yet up to the task of handling too much power from renewable sources.”
In Kenya’s Laikipia County where temperatures can reach as high as 30 degrees Celsius, a local building technology is helping homes stay cooler while supporting education, creating jobs and improving the livelihoods and resilience of community residents, Climate Home News found on a visit to the region.
Situated in a semi-arid region, houses in Laikipia are mostly built with wood or cement blocks with corrugated iron sheets for roofing. This building method usually leaves the insides of homes scorching hot – and as global warming accelerates, the heat is becoming unbearable.
Peter Muthui, principal of Mukima Secondary School in Laikipia County, lived in these harsh conditions until 2023, when the Laikipia Integrated Housing Project began in his community.
The project uses compressed earth block (CEB) technology, drawing on traditional building methods and local materials – including soil, timber, grass and cow dung – to keep buildings cool in the highland climate. The thick earth walls provide insulation against the heat.
Peter Muthui, principal of Mukima Secondary School in Laikipia County, stands in front of classroom blocks built with compressed earth blocks (Photo: Vivian Chime)
Peter Muthui, principal of Mukima Secondary School in Laikipia County, stands in front of classroom blocks built with compressed earth blocks (Photo: Vivian Chime)
“Especially around the months of September all the way to December, it is very, very hot [in Laikipia], but as you might have noticed, my house is very cool even during the heat,” Muthui told Climate Home News.
His school has also deployed the technology for classrooms and boarding hostels to ensure students can carry on studying during the hottest seasons of the year. This way, they are protected from severe conditions and school closures can be avoided. In South Sudan, dozens of students collapsed from heat stroke in the capital Juba earlier this year, causing the country to shutter schools for weeks.
COP30 sees first action call on sustainable, affordable housing
The buildings and construction sector accounts for 37% of global emissions, making it the world’s largest emitter of greenhouse gases, according to the UN Environment Programme (UNEP). While calls to decarbonise the sector have grown, meaningful action to cut emissions has remained limited.
At COP28 in Dubai, the United Arab Emirates and Canada launched the Cement and Concrete Breakthrough Initiative to speed up investment in the technologies, policies and tools needed to put the cement and concrete industry on a net zero-emissions path by 2050.
Canada’s innovation minister, François-Philippe Champagne, said the initiative aimed to build a competitive “green cement and concrete industry” which creates jobs while building a cleaner future.
Coordinated by UNEP’s Global Alliance for Buildings and Construction, the council has urged countries to embed climate considerations into affordable housing from the outset, “ensuring the drive to deliver adequate homes for social inclusion goes hand in hand with minimising whole-life emissions and environmental impacts”.
Homes built with compressed earth blocks in Laikipia (Photo: Julián Reingold)
Homes built with compressed earth blocks in Laikipia (Photo: Julián Reingold)
With buildings responsible for 34% of energy-related emissions and 32% of global energy demand, and 2.8 billion people living in inadequate housing, the ICBC stressed that “affordable, adequate, resource-efficient, low-carbon, climate-resilient and durable housing is essential to a just transition, the achievement of the Sustainable Development Goals and the effective implementation of the Paris Agreement”.
Compressed earth offers local, green alternative
By using locally sourced materials, and just a little bit of cement, the compressed earth technology is helping residents in Kenya’s Laikipia region to build affordable, climate-smart homes that reduce emissions and environmental impacts while creating economic opportunities for local residents, said Dacan Aballa, construction manager at Habitat for Humanity International, the project’s developers.
Aballa said carbon emissions in the construction sector occur all through the lifecycle, from material extraction, processing and transportation to usage and end of life. However, by switching to compressed earth blocks, residents can source materials available in their environment, avoiding nearly all of that embedded carbon pollution.
According to the World Economic Forum (WEF), global cement manufacturing is responsible for about 8% of total CO2 emissions, and the current trajectory would see emissions from the sector soar to 3.8 billion tonnes per year by 2050 – a level that, compared to countries, would place the cement industry as one of the world’s top three or four emitters alongside the US and China.
Comparing compressed earth blocks and conventional materials in terms of carbon emissions, Aballa said that by using soil native to the area, the process avoids the fossil fuels that would normally have been used for to produce and transport building materials, slashing carbon and nitrogen dioxide emissions.
The local building technology also helps save on energy that would have been used for cooling these houses as well as keeping them warm during colder periods, Aballa explained.
Justin Atemi, water and sanitation officer at Habitat for Humanity, said the brick-making technique helps reduce deforestation too. This is because the blocks are left to air dry under the sun for 21 days – as opposed to conventional fired-clay blocks that use wood as fuel for kilns – and are then ready for use.
Women walk passed houses in the village of Kangimi, Kaduna State, Nigeria (Photo: Sadiq Mustapha)
Traditional knowledge becomes adaptation mechanism
Africa’s red clay soil was long used as a building material for homes, before cement blocks and concrete became common. However, the method never fully disappeared. Now, as climate change brings higher temperatures, this traditional building approach is gaining renewed attention, especially in low-income communities in arid and semi-arid regions struggling to cope with extreme heat.
From Kenya’s highlands to Senegal’s Sahelian cities, compressed earth construction is being repurposed as a low-cost, eco-friendly option for homes, schools, hospitals – and even multi-storey buildings.
Senegal’s Goethe-Institut in Dakar was constructed primarily using compressed earth blocks. In Mali, the Bamako medical school, which was built with unfired mud bricks, stays cool even during the hottest weather.
And more recently, in Nigeria’s cultural city of Benin, the just-finished Museum of West African Art (MOWA) was built using “rammed earth” architecture – a similar technology that compresses moist soil into wooden frames to form solid walls – making it one of the largest such structures in Africa.
David Sathuluri is a Research Associate and Dr. Marco Tedesco is a Lamont Research Professor at the Lamont-Doherty Earth Observatory of Columbia University.
As climate scientists warn that we are approaching irreversible tipping points in the Earth’s climate system, paradoxically the very technologies being deployed to detect these tipping points – often based on AI – are exacerbating the problem, via acceleration of the associated energy consumption.
The UK’s much-celebrated £81-million ($109-million) Forecasting Tipping Points programme involving 27 teams, led by the Advanced Research + Invention Agency (ARIA), represents a contemporary faith in technological salvation – yet it embodies a profound contradiction. The ARIA programme explicitly aims to “harness the laws of physics and artificial intelligence to pick up subtle early warning signs of tipping” through advanced modelling.
We are deploying massive computational infrastructure to warn us of climate collapse while these same systems consume the energy and water resources needed to prevent or mitigate it. We are simultaneously investing in computationally intensive AI systems to monitor whether we will cross irreversible climate tipping points, even as these same AI systems could fuel that transition.
The computational cost of monitoring
Training a single large language model like GPT-3 consumed approximately 1,287 megawatt-hours of electricity, resulting in 552 metric tons of carbon dioxide – equivalent to driving 123 gasoline-powered cars for a year, according to a recent study.
GPT-4 required roughly 50 times more electricity. As the computational power needed for AI continues to double approximately every 100 days, the energy footprint of these systems is not static but is exponentially accelerating.
And the environmental consequences of AI models extend far beyond electricity usage. Besides massive amounts of electricity (much of which is still fossil-fuel-based), such systems require advanced cooling that consumes enormous quantities of water, and sophisticated infrastructure that must be manufactured, transported, and deployed globally.
The water-energy nexus in climate-vulnerable regions
A single data center can consume up to 5 million gallons of drinking water per day – sufficient to supply thousands of households or farms. In the Phoenix area of the US alone, more than 58 data centers consume an estimated 170 million gallons of drinking water daily for cooling.
The geographical distribution of this infrastructure matters profoundly as data centers requiring high rates of mechanical cooling are disproportionately located in water-stressed and socioeconomically vulnerable regions, particularly in Asia-Pacific and Africa.
At the same time, we are deploying AI-intensive early warning systems to monitor climate tipping points in regions like Greenland, the Arctic, and the Atlantic circulation system – regions already experiencing catastrophic climate impacts. They represent thresholds that, once crossed, could trigger irreversible changes within decades, scientists have warned.
Yet computational models and AI-driven early warning systems operate according to different temporal logics. They promise to provide warnings that enable future action, but they consume energy – and therefore contribute to emissions – in the present.
This is not merely a technical problem to be solved with renewable energy deployment; it reflects a fundamental misalignment between the urgency of climate tipping points and the gradualist assumptions embedded in technological solutions.
The carbon budget concept reveals that there is a cumulative effect on how emissions impact on temperature rise, with significant lags between atmospheric concentration and temperature impact. Every megawatt-hour consumed by AI systems training on climate models today directly reduces the available carbon budget for tomorrow – including the carbon budget available for the energy transition itself.
The governance void
The deeper issue is that governance frameworks for AI development have completely decoupled from carbon budgets and tipping point timescales. UK AI regulation focuses on how much computing power AI systems use, but it does not require developers to ask: is this AI’s carbon footprint small enough to fit within our carbon budget for preventing climate tipping points?
There is no mechanism requiring that AI infrastructure deployment decisions account for the specific carbon budgets associated with preventing different categories of tipping points.
Meanwhile, the energy transition itself – renewable capacity expansion, grid modernization, electrification of transport – requires computation and data management. If we allow unconstrained AI expansion, we risk the perverse outcome in which computing infrastructure consumes the surplus renewable energy that could otherwise accelerate decarbonization, rather than enabling it.
With global consensus over climate action faltering on the accord’s 10th anniversary, experts say “coalitions of the willing” should move faster and with more ambition
Rising demand in Southeast Asia and India is expected to prevent coal use from falling significantly this decade, the International Energy Agency predicts
What would it mean to resolve the paradox?
Resolving this paradox requires, for example, moving beyond the assumption that technological solutions can be determined in isolation from carbon constraints. It demands several interventions:
First, any AI-driven climate monitoring system must operate within an explicitly defined carbon budget that directly reflects the tipping-point timescale it aims to detect. If we are attempting to provide warnings about tipping points that could be triggered within 10-20 years, the AI system’s carbon footprint must be evaluated against a corresponding carbon budget for that period.
Second, governance frameworks for AI development must explicitly incorporate climate-tipping point science, establishing threshold restrictions on computational intensity in relation to carbon budgets and renewable energy availability. This is not primarily a “sustainability” question; it is a justice and efficacy question.
Third, alternative models must be prioritized over the current trajectory toward ever-larger models. These should include approaches that integrate human expertise with AI in time-sensitive scenarios, carbon-aware model training, and using specialized processors matched to specific computational tasks rather than relying on universal energy-intensive systems.
The deeper critique
The fundamental issue is that the energy-system tipping point paradox reflects a broader crisis in how wealthy nations approach climate governance. We have faith that innovation and science can solve fundamental contradictions, rather than confronting the structural need to constrain certain forms of energy consumption and wealth accumulation. We would rather invest £81 million in computational systems to detect tipping points than make the political decisions required to prevent them.
The positive tipping point for energy transition exists – renewable energy is now cheaper than fossil fuels, and deployment rates are accelerating. What we lack is not technological capacity but political will to rapidly decarbonize, as well as community participation.
Deploying energy-intensive AI systems to monitor tipping points while simultaneously failing to deploy available renewable energy represents a kind of technological distraction from the actual political choices required.
The paradox is thus also a warning: in the time remaining before irreversible tipping points are triggered, we must choose between building ever-more sophisticated systems to monitor climate collapse or deploying available resources – capital, energy, expertise, political attention – toward allaying the threat.
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