COP29 host nation Azerbaijan has proclaimed a lofty ambition for this year’s UN climate summit: pausing the conflicts currently wreaking havoc around the world.
If governments follow Baku’s plan, theatres of war – from Gaza to Ukraine – would fall still next month while diplomats fight over the finer details of climate action under the “COP Truce” vision championed by the Azerbaijan presidency of the November 11-22 COP29 talks.
Baku has spoken proudly of its initiative gaining “significant traction”, with 127 countries and nearly 1,100 non-state groups supporting the appeal so far.
But a list of early endorsers features several warring states, deepening skepticism about the real impact and intentions of the initiative at a time when conflicts – which number more than 50 today – are provoking insecurity and severe humanitarian crises in many parts of the globe.
Speaking to Climate Home, veteran climate campaigners and geopolitical experts criticised the COP Truce as a “performative… PR exercise” and “a distraction” from a separate UN-supported push to strengthen climate action in conflict-affected regions.
Meanwhile, as hopes dwindle of Azerbaijan clinching its own peace deal with neighbour Armenia by COP29, Laurence Broers, associate fellow with Chatham House’s Russia and Eurasia Programme, warned about the risks of the “peace COP brand” looking “empty of content”.
World peace aspirations
Alongside the formal government negotiations, the annual climate summits see COP presidencies launch an ever-growing list of voluntary initiatives, hoping to get as many as possible governments, business groups and civil society organisations to sign onto them.
Azerbaijan has pinned its appeal for a “COP Truce” at the top of its list of voluntary declarations for COP29. Taking inspiration from the Olympic Truce, first established in ancient Greece, Baku wants all fighting parties worldwide to lay down their arms while country leaders and diplomats discuss climate policy.
Modi, Macron, Xi and Biden among many leaders yet to request COP29 speech
The initiative “will highlight the importance of peace and climate action” and “aim to remind all nations of the interplay between conflict and climate change”, the COP29 presidency said.
The centrepiece is a 10-line “solemn appeal”, which governments and observer groups are being urged to endorse.
Its signatories “call on everyone to observe the COP Truce during the month of COP29” – but they are not required to explicitly commit to cease hostilities themselves. “It is a generic appeal for the international community to observe a ceasefire during the COP,” Yalchin Rafiyev, Azerbaijan’s lead negotiator for COP29, told Climate Home at a press briefing.
The inherent paradox is exemplified by some of the early backers of the initiative.
War-waging signatories
Azerbaijan’s Ministry of Foreign Affairs announced that the truce appeal has been supported by all member states of the “Non-Aligned Movement”, a forum of 120 countries originally set up in the Cold War era as a buffer between the United States and the Soviet Union.
The movement counts among its members several countries now involved in bloody civil wars and international conflicts, including Sudan, Myanmar and Palestine.
A Sudanese national flag is attached to a machine gun of Paramilitary Rapid Support Forces (RSF) soldiers. (Photo: REUTERS/Umit Bektas/File)
A COP29 official did not reply to Climate Home’s question asking what concrete purpose the COP Truce initiative would serve given the presence of warring countries among its signatories. But in emailed comments, they said the appeal “is meant to enhance ambition, set aside differences, and prioritize peace and climate action”.
The COP29 presidency has also been enlisting international non-state organisations to support the initiative, alongside governments.
It said nearly 1,100 groups have put their name next to the appeal so far. Climate Home requested a full list of signatories but a COP29 official said that would not be shared until November 15 during COP’s “Peace, Relief and Recovery Day”.
The only publicly available information shows support from around 100 NGOs linked to the Baku-based chapter of the Islamic Cooperation Youth Forum. Listed signatories feature a wide range of predominantly grassroots groups in Central and Southeast Asia, including Uzbekistan’s ‘Council of Young Farmers’ and Azerbaijan’s ‘Erasmus Student Network’.
Scepticism and mild support
Climate Home has surveyed around a dozen international organisations deeply involved in the climate, conflict and human rights agendas at the COP. It found deep scepticism in some quarters – and no more than limited support for the initiative in others.
Tasneem Essop, executive director of the influential Climate Action Network and coordinator of the coalition of environmental non-governmental organisations (ENGO) at the UN talks, told Climate Home that the Azerbaijan presidency had approached the UNFCCC Observer Constituencies – including ENGO – in early September asking them to endorse the truce declaration.
“We had a number of important questions about the practical implications of the declaration and what it meant, for example, for our efforts to spotlight human rights abuses,” she said. “But they did not give us the time to engage properly, so obviously we did not sign on.”
Essop also said that “in its current form, it is a hollow and performative ‘motherhood and apple pie’ declaration that does not deal with the fundamental and systemic issues causing wars and conflict.”
“At best, it appears to simply be a PR exercise,” she added.
On the other hand, the COP Truce appeal has received the support of a different UN constituency representing local government and municipal authorities. Its coordinator Yunus Arikan, director of global advocacy at local government sustainability group ICLEI, told Climate Home they hoped the initiative could have “transformative impacts” despite the “huge challenges that lie ahead”.
“But even if this may not fulfill all its aspirations, we still believe it is a worthwhile effort, as it is a moral duty of all governments and leaders to prevent destruction of our livelihoods, either as a result of climate change or through armed conflicts and wars,” he added.
Conflict blind spot in climate action
Nonetheless, Azerbaijan’s appeal has raised an eyebrow among organisations that have been at the forefront of efforts to put a spotlight on the nexus between climate change and conflict at UN climate summits.
The UAE COP28 presidency last year inaugurated a thematic day dedicated to the connection between climate and peace. It culminated in a detailed declaration through which over 100 governments, NGOs and private-sector institutions committed to scale up climate action, including channeling more investment, in war-torn regions.
London-based think-tank ODI was one of the driving forces behind last year’s declaration, but told Climate Home it won’t be throwing its weight behind Azerbaijan’s ceasefire appeal.
“The COP29 Truce is a nice idea but it’s ultimately a distraction – and one that was always unlikely to succeed, as we saw from the failed Olympic truce earlier this year,” said Mauricio Vazquez, ODI’s head of policy for global risks and resilience.
Comment: Why we need new laws to end coal, oil and gas – now
“Noise” from the truce day should not deflect the focus from the “huge” conflict blind spot in climate action, he added.
“More than half of the world’s most climate-vulnerable countries are also fragile or experiencing conflict – yet they receive only a fraction of the finance which goes to more stable places,” Vazquez said. “A temporary truce will not fix these issues.”
Humanitarian aid group Mercy Corps – another signatory of the COP28 declaration – told Climate Home it is still weighing up whether to join Azerbaijan’s truce appeal, but added that its focus is primarily on building momentum from last year’s initiative and turning pledges into action.
Nagorno-Karabakh legacy
Notwithstanding any concrete outcomes, the initiative is also widely seen by geopolitical analysts as an attempt by Azerbaijan to burnish its peace credentials just over a year after putting a forceful end to its decades-long conflict with Armenia over the enclave of Nagorno-Karabakh.
Baku conquered the contested region in a two-part military offensive, concluding in autumn 2023, that led to the mass exodus of some 136,000 ethnic Armenians. For Armenian authorities and some human rights and legal experts, the drive amounted to “ethnic cleansing” – a view Azerbaijan categorically rejects.
In Nagorno-Karabakh, Azerbaijan’s net zero vision clashes with legacy of war
Top Azeri diplomats and government officials have drawn a direct link between the conflict in Nagorno-Karabakh and the COP29 peace appeal.
Hikmet Hajiyev, chief foreign policy advisor to Azerbaijan’s President Ilham Aliyev, wrote last week in an op-ed for Newsweek that it “would be a mistake for us not to try” pushing for a COP Truce “when the COP29 meeting in Baku is itself the product of a truce – one few believed possible”.
Hajiyev was referring to a deal struck between Azerbaijan and Armenia in December 2023 that paved the way for Baku to host this year’s climate summit. Armenia backed Azerbaijan’s COP29 bid, while Baku agreed to release 32 Armenian prisoners captured during the Nagorno-Karabakh conflict.
Faltering peace process
That agreement was interpreted as a potential stepping stone towards a fully-fledged peace deal between the two nations, with watchers seeing COP29 as an ideal backdrop for the much-trailed accord to be finalised.
But hopes of that dwindled last week after President Aliyev turned down Armenia’s latest proposal to sign a peace deal, describing it as “unrealistic”. Armenia is absent from a preliminary list of countries sending their heads of state to speak at COP29’s high-level opening session, raising doubts over the participation of the country’s leaders at the summit.
Broers, of London-based think-tank Chatham House, said he does not expect the signing of a “significant” agreement “before, at or for a long time after the COP29 conference”.
“The statements in recent days and weeks show they are a long way off,” he told Climate Home. “What might be meaningful would be for Baku and Yerevan to use the COP29 venue to sign off on a new package of confidence-building measures on joint environmental action. Without some such steps, the whole ‘peace COP’ brand looks empty of content.”
(Reporting by Matteo Civillini; editing by Megan Rowling)
The post In a warring world, Azerbaijan’s COP29 truce appeal draws fire as “PR exercise” appeared first on Climate Home News.
In a warring world, Azerbaijan’s COP29 truce appeal draws fire as “PR exercise”
Climate Change
Greenpeace welcomes renewed solar push, urges global leadership away from fossil fuels
SYDNEY, Wednesday 5 August 2026 — Greenpeace has welcomed Minister Chris Bowen’s commitment to expanding Australia’s solar discount at his National Press Club address today, a move it says unlocks the potential of Australia’s commercial rooftops, and underscores how homegrown renewables strengthen energy security and affordability in an increasingly volatile world.
The announcement comes three months before Minister Bowen is due to take the reins of UN climate negotiations, and shortly ahead of the Pacific Islands Forum and Pacific Pre-COP — two moments that will test Australia’s determination as incoming COP31 President of Negotiations and bring global attention to Australia’s fossil fuel exports.
Dr Simon Bradshaw, COP31 Lead at Greenpeace Australia Pacific, said: “Homegrown, decentralised renewable energy is the path to energy security, affordability, and to protecting communities from escalating climate disasters.
“We commend Minister Bowen for building on Australia’s world-leading progress in shifting homes and businesses beyond fossil fuels. Now the Australian Government has a responsibility to help drive stronger progress globally, and to tackle Australia’s burgeoning fossil fuel exports.
“Right now, as the northern hemisphere burns and Australians grow anxious at the prospect of another dangerous El Niño summer, all efforts of Australian families and businesses in shifting to renewable energy are being undone by the pollution from Australia’s exported coal and gas.
“COP31 is a unique opportunity for Australia to work with its big energy trade partners like South Korea and Japan towards a prosperous shared future beyond fossil fuels.
“Continuing to approve new fossil fuels, like Woodside’s mammoth Browse gas project, would be an historic act of recklessness at a pivotal moment in the world’s energy transition and response to the climate crisis.
“Australia must get squarely behind longstanding Pacific leadership on climate change, fight to protect the all-important goal of limiting warming to 1.5°C, and ensure that COP31 builds further momentum in the global transition away from fossil fuels.
“As we heard today, Australia is making real strides in its own energy transition. It’s time to match that domestic resolve with the kind of global leadership the Australian Government has promised, and that communities here, in the Pacific and worldwide are depending on.”
-ENDS-
Media contact
Kate O’Callaghan on 0406 231 892 or kate.ocallaghan@greenpeace.org
Greenpeace welcomes renewed solar push, urges global leadership away from fossil fuels
Climate Change
Is FOMO undermining climate diplomacy?
Benito Müller, Anju Sharma, Jen Allan, Matthias Roesti and Luis Gomez-Echeverri.
Every November, tens of thousands of people descend on the world’s annual UN climate conference. Presidents and prime ministers, negotiators, business executives, campaigners, journalists, celebrities and lobbyists converge on one city for two frenetic weeks, all convinced they need to be there.
Everyone with a stake in climate action feels they must be present. Any suggestion of a smaller, more focused conference is quickly met with concerns about exclusion. But it is time to ask an uncomfortable question: has the fear of missing out (FOMO) become one of the biggest obstacles to effective international climate cooperation?
The story in numbers
When governments first met under the UN Framework Convention on Climate Change (UNFCCC) in the 1990s, the annual Conferences of the Parties (COPs) attracted only a few thousand participants. Even the Kyoto conference, which produced the first legally binding emissions agreement, hosted fewer than 10,000 people.
Since then, analysis by ecbi reveals a striking trend: after each major treaty COP, the participation at the next COP approximately doubled (see chart below).
Why?
Part of the answer is success. As climate change has risen up the political and economic agenda, more actors quite rightly want to engage. But our analysis reveals that a less acknowledged force is also driving the spikes in participation: FOMO.
As more heads of state attended, ministers concluded they had to be there too. As ministers arrived in greater numbers, government delegations expanded. Businesses, investors, researchers, campaigners, journalists, city leaders and philanthropies reached the same conclusion: if everyone important is going to COP, we cannot afford to stay away.
The result is a self-reinforcing cycle. The larger COP becomes, the more indispensable attendance appears, because presence signals relevance.


The negotiating community has barely grown
The headline attendance figures tell only part of the story. At COP28, more than 42,000 Party badges were issued to official national delegations. However, only 1,581 delegates had also attended the technical negotiating session in Bonn just five months earlier. Fewer than 4% of Party delegates formed the core negotiating community.
Comment: The UN climate process was built for negotiation – now it must support implementation
This core negotiating community has remained remarkably stable: across the five COPs since Paris, between roughly 1,300 and 1,600 delegates consistently attended both the June negotiating session and the annual COP.
The negotiating community has not become twenty times larger, but the COP has.
One COP, three different events
Today’s COP has, in fact, evolved into three very different events rolled into one.
The first is the formal negotiating session, where governments agree rules, guidance and decisions under the Convention and the Paris Agreement.
The second is a global political summit, where leaders announce initiatives and demonstrate political commitment.
The third is a vast climate expo, where businesses, cities, researchers, financial institutions and civil society showcase solutions, build partnerships and engage the public.
Each of them serves a valuable purpose, but the problem is that they have become bundled together by historical accident rather than institutional design.
Bigger is not always better
The consequences of “mega-COPs” are becoming increasingly difficult to ignore.
The countries most vulnerable to climate change are increasingly less able to host COPs and thus lose the ability to have their voices properly heard. Hosting a modern COP now requires enormous financial resources, extensive security operations and accommodation capacity that many countries simply do not possess. Even wealthier nations have become more reluctant to take on the burden.
Inside the venue, size creates its own inefficiencies. Climate negotiations often advance through informal conversations: a chance meeting in a corridor, a discussion over coffee, an impromptu conversation between delegates who discover common ground. Those opportunities become rarer when participants spend hours navigating enormous venues and crowded security checkpoints.
Comment: COP presidencies should focus less on climate policy, more on global politics
Observer access is constrained by overcrowding. National delegations increasingly include large numbers of non-government participants, sometimes outnumbering officials from government ministries. Meanwhile, businesses, campaigners and journalists compete with negotiators for the same space and attention.
The very scale of the event also creates a reputational problem. A gathering of 60,000 or more people inevitably creates expectations of dramatic political breakthroughs every year. Yet much of today’s climate diplomacy involves steady, technical progress. When those quieter achievements are judged against the expectations generated by a mega-event, disappointment in the UN climate change process becomes almost inevitable.
Time to unbundle
Not everything must happen in the same place at the same time. Negotiations, political leadership and implementation partnerships each deserve their own space. They should become separate events.
Routine governing body sessions, involving the roughly 5,000 participants directly engaged in the formal process, could be held in Bonn, where the UN climate secretariat is based. Political summits could be convened separately when leaders’ intervention is genuinely needed. Climate expos could continue to rotate with the COP Presidency, providing dedicated opportunities for businesses, investors, cities, researchers and civil society to showcase solutions and forge partnerships.
Such an approach would strengthen, not weaken, participation. Negotiators would benefit from a more focused and effective working environment. Host countries would face a far more manageable logistical and financial challenge. Climate-vulnerable countries would once again have a realistic opportunity to host key meetings and shape the global agenda. Businesses, investors, cities and civil society would gain greater visibility by engaging in forums designed for partnership, innovation and implementation, rather than competing with formal negotiations for space and attention.
Comment: Not another COP-out: We must rewrite the rules of the UN climate talks
Today’s mega-COPs evolved incrementally, one seemingly sensible decision at a time, until their sheer scale began to undermine many of the objectives they were intended to serve. The fear of missing out now risks becoming one of the biggest barriers to the reforms needed to make the process more effective.
The greatest fear now is not missing out on the next COP, but missing the opportunity to redesign the process so it can deliver on its ultimate purpose: tackling the climate crisis.
Benito Müller is managing director of Oxford Climate Policy and director of the European Capacity Building Initiative (ecbi).
Anju Sharma is a climate policy specialist with Oxford Climate Policy.
Jen Allan is a senior Lecturer at Cardiff University and strategic advisor at the International Institute for Sustainable Development.
Matthias Roesti is a postdoctoral researcher studying the political economy of climate change at the University of Pennsylvania’s Environmental Politics Lab.
Luis Gomez-Echeverri is a former senior staff member with UNDP and UNFCCC and currently an emeritus research scholar at the International Institute for Applied Systems Analysis, working at the intersection of climate and development.
The post Is FOMO undermining climate diplomacy? appeared first on Climate Home News.
Climate Change
Factcheck: How nuclear, gas, wind and solar power are affected during heatwaves
Heatwaves are becoming more likely and more intense due to climate change, impacting sources of power generation around the world as they work to meet increased demand.
When temperatures soared past 40C in parts of Europe in June and July 2026, nuclear reactors shuttered, gas plants’ efficiency fell, wind speeds dropped and electricity networks sagged.
Yet, while all types of electricity generation are affected variously by extreme heat, some commentators are quick to point the finger at “intermittent” wind and solar, while downplaying the impact on sources such as gas or nuclear power.
Extreme heat also drives up electricity demand, as people turn on air conditioning and fridges work harder.
For example, in France, daily electricity demand rose by almost 20% during a two-week heatwave in June 2026.
This often leads to an increase in power prices, as generation strains and demand rises, putting a premium on electricity.
Below, Carbon Brief – amid a slew of misleading claims – explains how key power sources cope with extreme heat.
Nuclear
The impact of heatwaves on nuclear power generation is well documented, with a plethora of headlines often accompanying record temperatures in nations that rely on the technology.
For example, around 70% of electricity is generated by nuclear power in France, leaving it vulnerable to the impacts of heatwaves.
During the July 2026 heatwave, three of France’s 57 nuclear reactors had to shut down. Generation was reduced at another seven, causing an almost 9% dip in power production.
(This is a well-known phenomenon – France has seen reductions in nuclear generation due to heatwaves in 2003, 2006, 2015, 2018, 2019, 2022 and 2025.)
A similar story is true across various countries in Europe. Low river levels on the Danube have hit nuclear reactors in Romania, Hungary and Serbia this summer, while a Swiss nuclear reactor shuttered due to high river temperatures.
It is nuclear plants using river water to cool their reactors that are most significantly affected by heatwaves and droughts. These make up 14% of the global fleet. Around 60 of the world’s 440 river-cooled reactors are located in France, with a further seven across Europe.
Nuclear power plants use fission to generate heat, which is used to create steam. This steam spins the blades of a turbine that is connected to a generator to create electricity.
Following this process, the water is cooled to allow it to be recycled back through the system as steam again. Nuclear power plants generally use water from rivers or the sea to help cool and condense this steam.
As such, when water temperatures rise due to a heatwave, their cooling capacity is reduced and the overall efficiency of the nuclear power station is affected. Similarly, if there is less water available due to drought, they cannot be cooled as effectively.
Michael Tadrous, a researcher at McMaster University’s DeGroote School of Business in Canada, tells Carbon Brief that the “impact [of heatwaves] is real, but it is far smaller than many headlines suggest” and that the “effect [of heat] is gradual”. He adds:
“Warmer intake water makes a reactor slightly less efficient. [But] even an extreme 15C rise in cooling-water temperature would cost a large reactor only about 6% of its output.
“The real pressure point during a heatwave is usually legal rather than technical. Plants return their cooling water to the river a few degrees warmer than they drew it and the law limits how warm that water may be in order to protect aquatic life.”
Henry Preston, a spokesperson for the industry body the World Nuclear Association, adds that reactor shutdowns due to high river temperatures are “typically an automatic response to comply with regulations to protect local ecosystems, rather than a technological fault”.
He notes that in some extreme heatwaves, these regulations are waived given the “essential need for electricity and taking a proportional approach to climate risks”.
While nuclear power plants can generally return to standard operation quickly if they have been affected by high water temperatures, drought can cause a more significant impact.
Preston tells Carbon Brief:
“In contrast to high river temperatures, which can quickly return to acceptable levels once a heatwave passes, low river levels can persist for much longer, if drought conditions continue. As a result, low water levels may have a more prolonged impact on plant operations than elevated water temperatures.”
This is set to be the case in the current European drought, where multiple reactors in Hungary and Romania have shut down or reduced their output due to low water levels.

The Danube is not expected to return to normal water levels for “days or even weeks as no significant rainfall is forecast”, reported the Associated Press on 3 August 2026. It said this was “push[ing] some countries in eastern Europe to the brink of energy emergency”.
While heatwaves and drought can produce significant short-term effects, their impact on the availability of nuclear power across a full year is generally minimal.
On average, heatwaves cut annual nuclear generation by 0.6% between 2003 and 2022, according to a recent study that Tadrous co-authored.
He adds that, across the whole period studied, the only time a national nuclear fleet lost more than 1% of its nuclear power over a year to heat- and drought-related curtailments was France in 2003, which lost 1.3%.
According to an article in Forbes, for every additional degree Celsius in temperature, a nuclear power plant loses around 0.6-1% in cycle efficiency.
To minimise the impact on both energy security and costs, governments and nuclear companies are looking at a range of solutions to adapt to heatwaves.
For example, French nuclear-plant operator EDF is looking at additional cooling towers for its sites that are the most exposed to the impacts of a warming climate, reported Bloomberg recently.
Tadrous says the nuclear power industry is already adapting to heatwaves that are “more frequent and more intense”, adding:
“France’s river-cooled fleet lost 5.5 terawatt hours (TWh) of output to the 2003 heatwave. By 2022, one of the most severe heat-and-drought summers on record, losses had fallen to 0.5TWh, a reduction of roughly 90%, as utilities upgraded cooling systems, refined operating practices and scheduled maintenance around periods of extreme heat.”
There remain challenges for adapting nuclear power – and the wider electricity systems in which it sits – to heatwaves. However, Tadrous notes that this is less about “technical feasibility than of economic prioritisation and timely implementation”.
Gas
Gas power plants have a reputation for being reliable and able to switch on at any moment, sometimes referred to as “firm, dispatchable” capacity.
Yet, as a type of thermal generation, they are subject to many of the same stresses during heatwaves as nuclear power.
An article by the science advocacy organisation Union of Concerned Scientists (UCS) notes that the “purported ability of gas plants to be available at all times to generate electricity, particularly when the grid needs it most, is increasingly under scrutiny” due to heatwaves.
As a matter of physics, the efficiency of gas power plants drops as temperatures rise. At 40C, a gas-fired power station can expect its capacity to be reduced by 13% and its efficiency by 7% compared to when running at 20C, according to Electric Insights.
Dr Iain Staffell, associate professor in sustainable energy at Imperial College London, tells Carbon Brief:
“Simple gas turbines (the kind which turn on rapidly to meet peak demand) are hit harder [than solar, for example], with their power output falling by about 10% per 10C.”
(He adds that the transmission system struggles more than electricity generation during high temperature. Power line capacity can fall by up to 16% for a 10C rise in temperature, according to a report for the UK government.)
Several types of gas power plants require cooling as part of their process, including gas steam and combined cycle turbines (CCGTs). They usually rely on nearby bodies of water for this.
Additionally, as the UCS article notes, hot air has a lower density than cool air. As gas CCGTs rely on burning a mix of gas and air, this lower density means air takes up more space, leaving less room for gas.
Ultimately, this means that when the air is hot, gas power plants cannot generate as much electricity as normal.
These effects are not just theoretical. For example, across two nights in August 2020, there were rolling blackouts in California, US, as demand exceeded supply amid a heatwave.
While a number of factors contributed to the blackouts, gas plants made up around 79% of the capacity that dropped off the system on 14 August and a similar share the following day.
Amid record-breaking heat in summer 2026, gas power plants have also seen their capacity cut in the UK, France and other countries.

Dr Staffell adds that gas power stations are thought of as “reliable, because of the way we use them” in the UK.
Whereas wind and solar are usually used to the maximum extent possible, he says that on average, only around 40% of the gas fleet is in use at any one time. As such, even if the efficiency of one gas power plant is affected by high temperatures, “we have a lot of slack to call on more of them to run”. He adds:
“The issue is less that they can’t deliver, but we have to pay through the nose to persuade more to turn on at critical times, adding to sky-high energy bills.”
Wind
The impact of heatwaves on wind generation is less direct than for other technologies.
However, wind speeds often drop during heatwaves, which tend to build during periods of sustained high pressure into extreme events such as “heat domes”.
Dr Staffell, explains to Carbon Brief:
“The very hottest days tend to create heat domes with very low wind speeds, which directly reduces the output that windfarms can produce. Air is also less dense the hotter it is, so it carries less energy within it, so there is a double impact on wind turbines.”
High temperatures are linked to low wind speeds across three-quarters of the globe, according to one recent study, looking at data from 1980 to 2023.
The study found that, as a result, across Australia, northern Asia and Europe, wind power decreased by an average of 30-50% during heatwaves.
This is inconsistent globally, however, with the Amazon, the Great Plains in North America and central Africa actually seeing a slight increase in wind during high temperatures.
As such, while the effect of heatwaves on wind generation is less direct than other generation technologies, it can have a significant impact.
In the UK in June 2026, wind generation fell to around 15% of the electricity mix due to low wind speeds, from an average for the month of about 30%, according to Octopus.
Low wind generation during this period was a key feature of the strain on the grid experienced during this time – in particular, as demand rose amid record-high temperatures.
On Wednesday 24 June, for example, the National Electricity System Operator (Neso) had to pay high prices to balance supply and demand. This included paying as much as £1,400 a megawatt-hour to secure around 1.7 gigawatts (GW) of imported power, nearly 20 times the average price for electricity in June 2025.
A Neso spokesperson said in a statement: “This is due to the impact of extremely high temperatures affecting Great Britain and the continent, and low wind.”
While reduced wind generation is common during a heatwave, it is not generally viewed as a concern for energy system operators. This is due to wind following well-established seasonal patterns – it generates less power in summer than in winter – as well as being complementary to other renewable technologies, such as solar.
Dr Chris Rosslowe, senior energy analyst for Europe at Ember, tells Carbon Brief:
“Power systems are less reliant on wind power in the summer months and its lower-than-average output is already expected and planned for. Heatwaves often bring still, but clear conditions, highlighting the benefit of wind and solar as a duo – poor conditions for one often mean good conditions for the other.”
As such, wind power remains one of very few technologies considered “resilient” to heatwaves by the UK government.
However, this did not stop the anti-renewables Daily Mail from attempting to blame the technology for strain on the UK grid on 24 June 2026, despite its own article acknowledging that gas plants had also been forced to cut their output by 2.5GW on the day.
Solar
Another common claim seen in the media is that solar “struggles” during heatwaves, with high temperatures pushing down the technology’s efficiency.
Yet heatwaves tend to coincide with long, cloudless days, when solar generation is reliably above average – despite the impact of high temperatures.
While hot weather does reduce the efficiency of solar cells, the effect is relatively modest – and widely understood. Each 1C of temperature rise reduces output by around 0.4-0.5%, according to a recent study.
This is in line with an evidence review for the UK government, which suggests the performance of solar panels falls by 0.2-0.5% for every degree of heat above 25C.
Generally, however, this effect is easily outweighed by high sunlight hours during hot spells. For example, across a four-day heatwave in the UK in June 2026, solar generated 484 gigawatt-hours (GWh) of electricity – a 46% increase over the same period a week earlier.
Similar generation highs were seen across Europe, amid record temperatures and dangerous heat that was pushing people towards the use of air conditioning.
Solar generated a record 52TWh across the EU in June 2026, beating the high set just the month before of 47TWh.
In fact, solar – especially when combined with battery storage – is a complementary technology to air conditioning, given their similar seasonal patterns. Over the course of the day, demand from air conditioning and generation from solar also marry up well.
Dr Rosslowe says:
“Solar, battery storage and air conditioning are a highly complementary trio of technologies during heatwaves. There’s a high overlap between solar output and demand from AC.”
For example, on the hottest day of the year so far in Great Britain (the island grid serving England, Wales and Scotland), on 26 June 2026, solar surged to 13.9GW in the middle of the afternoon, as demand also hit its highest point, as shown in the chart below.

Across June 2026, homes with solar panels generated the equivalent of five hours of “free” self-supplied air conditioning, according to recent analysis.
Despite the impact of heat on solar efficiency, the technology is, therefore, well placed to bolster energy systems during heatwaves.
Indeed, as Dr Rosslowe tells Carbon Brief, solar suppresses power prices during daylight hours. But, even though it is predictable, there are still challenges around managing the dip in solar generation as the evening sets in. This is often compounded because it coincides with the usual evening increase in demand.
Dr Rosslowe explains:
“Problems arise when the sun goes down, but demand for cooling remains high. In the early evening hours, when gas power typically ramps up to replace solar, we have seen prices spike to extreme levels, made worse by high international gas prices.”
Storage
Energy storage systems are increasingly key to managing the impact of heatwaves on electricity systems.
The category of technologies is dominated by batteries, with more than 108GW of battery storage added in 2025 alone, according to the International Energy Agency.
Already, batteries have been used to take advantage of surges in solar generation during the daytime, amid high summer temperatures.
This is particularly useful to meet evening peaks in electricity demand, as well as the need for air conditioning overnight when temperatures do not fall.
In a statement, Pawel Czyzak , Europe programme director at Ember, said:
“Heatwaves will not go away – they will only get more severe in the future. Solutions that can help mitigate their impacts, such as battery storage, interconnection, demand flexibility and dynamic tariffs, should become a key part of grid planning and power market design.”
However, batteries are not without their challenges during heatwaves. Battery performance also decreases as temperatures exceed their optimal level.
Additionally, high temperatures can accelerate the degradation of components in lithium-ion batteries, which dominate the sector.
Analysis for the UK government found that prolonged operation at very high temperatures could – at least in theory – “overwhelm” the cooling systems built into batteries, “posing risks such as thermal runaway and explosions”. However, it noted that in practice, these cooling systems are “routinely” designed to handle temperatures of up to 45C.
(The analysis added that “developers and manufacturers have a strong understanding of risk to [battery storage systems] from high temperature and mitigate risks through regular maintenance, design improvements, and passive cooling strategies”.)
Other storage technologies also face challenges during heatwaves. For example, pumped hydro storage can be significantly impacted by drought.
Australia – which now has 4.3GW of large-scale battery storage capacity – saw its fleet of batteries and pumped hydro storage tested at the beginning of 2026, amid the most severe heatwave in years.
Temperatures above 40C posed “challenges” to storage technologies, reported Energy Storage News, which explained that their output and operating times were reduced by the increased need for their cooling systems to operate.
Despite these challenges, the use of battery storage is helping to spread the ability of renewables to meet electricity demand during heatwaves. For example, a combination of solar and battery energy storage “kept the lights on” in California amid a heatwave in 2024.
By storing abundant power during the day, it can be discharged during evening peaks, helping to minimise generation constraints and thereby keep power prices down.
Dr Rosslowe says:
“The extreme price spikes that we witness during heatwaves are a blaring signal for more power system flexibility. That could come from battery storage, demand response, or increased interconnection between countries or regions.”
The post Factcheck: How nuclear, gas, wind and solar power are affected during heatwaves appeared first on Carbon Brief.
Factcheck: How nuclear, gas, wind and solar power are affected during heatwaves
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