China’s carbon dioxide (CO2) emissions grew by 2% in the first quarter of 2026, after a rise in the amount of “wasted” wind and solar power.
The country used more coal and gas to generate electricity than in the same quarter a year earlier, despite a record amount of new wind and solar capacity being built.
While the strait of Hormuz crisis has boosted China’s focus on energy security – including through clean energy and electrification – its electricity system is failing to keep up.
The new analysis for Carbon Brief shows that, while China’s CO2 emissions from fossil fuels and industry increased in the first part of 2026, they remain below the peak in early 2024.
Other key findings for the first quarter of 2026 include:
- There was a 23% year-on-year rise in wind-power capacity and 33% for solar.
- There was also a sharp rise in the amount of wind and solar output being “wasted”, as it was not accommodated by the current electricity system.
- As a result, emissions in the power sector increased by 4% year-on-year.
- Power-sector CO2 would have been flat without the rise in “wasted” wind and solar.
- Emissions in other sectors of the economy grew by 1%.
The key reason for “wasted” wind and solar generation was the inflexible management of coal power plants and power grids, not a lack of grid infrastructure.
In the first quarter of 2026, China’s energy system also began to adjust to the surge in oil and gas prices due to the blockade of the strait of Hormuz.
This continued through April and May, with sharp reductions in oil imports and oil-based chemicals production, as well as the share of gas in electricity generation.
However, the inability to make full use of new wind and solar power plants left China more exposed to the closure of the strait of Hormuz, by increasing the need for other fuels.
This exposure could become more acute if the “super El Niño” that is forecast for later this year limits the electricity output of hydropower, while fossil-fuel supplies remain tight.
Nevertheless, the Hormuz crisis could result in China following a lower-CO2 trajectory than previously expected, if key policies in its 15th five-year plan are fully implemented.
Emissions plateau continues
Recent analysis for Carbon Brief showed that China’s CO2 emissions from fossil fuels and industry had been “flat or falling” for nearly two years.
The latest analysis points to a rise of 2% year-on-year in the first quarter of 2026, as shown in the figure below. For now, however, emissions remain below the peak in March 2024.
In previous quarters, emissions had fallen in almost every sector of the economy, with the exception of the coal-based chemicals industry.
The latest quarter saw more widespread increases, with the power sector by far the largest source of emissions growth, as shown in the figure below.
Emissions from other sectors were relatively stable in aggregate, with some rising and others continuing to decline.
Coal consumption in the chemical industry continued strong growth, increasing by 20%, but showed no change in trend after the closure of the strait of Hormuz and surge in oil prices.
(This is contrary to some commentary arguing that the closure of the strait of Hormuz has resulted in a marked increase in the output of China’s coal-chemicals industry.)
The apparent consumption of oil products rebounded in January-February, driven by transportation, but declined slightly in March as oil prices surged.
Emissions from the cement and steel industries continued to fall, as real estate investment contracted another 11% in the first quarter of 2026, following a 17% reduction in 2025. Cement production fell 7% and crude steel output by 5%.
‘Wasted’ wind and solar power
After falling in 2025, power generation from coal and gas increased by 4% in the first quarter of the year.
Power demand grew at 5.2% and hydropower generation increased 9%. Under these circumstances, the record growth in solar and wind power capacity in 2025 should have covered demand growth and pushed fossil-power generation down.
The trend was accentuated in March, as power demand grew just 3.5%, hydropower output increased 9% and yet fossil-power generation increased 4.2%.
The reason for fossil-power generation growth was a sharp drop in the electricity output per unit of installed capacity for both solar and wind power, known as the “capacity factor”.
If capacity factors were stable, the increased solar and wind capacity would have been expected to result in 160 terawatt hours (TWh) of additional clean-power generation during the first quarter, compared with the same time last year, with nuclear and hydro bringing the total to 170TWh. This would have comfortably exceeded the 120TWh increase in power demand.
However, the actual increase in clean-power generation was just 60TWh, with wind showing almost no growth.
While wind power capacity grew by 23% from the first quarter of 2025 to the same period in 2026, an increase of 120GW, the average capacity factor fell from 27% to 22%, a reduction of 18%. This implies that power generation from wind only grew 1% year-on-year. In the case of solar, capacity grew by 33%, but the average capacity factor fell by 11%, resulting in 18% growth in solar-power generation.
It is normal for solar and especially wind capacity factors to vary year-to-year due to weather conditions, but the fall this year was an extension of a longer trend. The average capacity factors of solar and wind have fallen by 19% and 10%, respectively, from 2022 to 2025.
A quarter of the fall in capacity factors over the three-year period is explained by the increase in reported curtailment. This refers to the amount of electricity that is effectively “wasted”, or curtailed, because it cannot be accommodated by the power network.
Nor can the remainder of the fall in capacity factors be explained by the change in weather conditions, as both wind and solar conditions improved on a national-average basis from 2022 to 2025.
In the first quarter of 2026, approximately half of the drop in wind capacity factor and a quarter of the drop in solar capacity factor was explained by weather conditions, implying that the rest is due to increased curtailment resulting from inadequate grid management and integration.
One clear symptom of increased curtailment is that in January-February, both solar and wind conditions were actually better than last year, but capacity factors still fell.
The fact that capacity factors have fallen significantly more than would be expected based on reported curtailment and weather conditions indicates that a lot of curtailment goes unreported, either because it is excluded from the statistical definition, or because there are gaps in reporting.
Market participants have long noted that actual curtailment is much higher than reported in official statistics.
Official data on curtailment only includes “system reasons”, while excluding some lost generation linked to market trading, grid-connection conditions and other “special” causes.
The figure below shows actual electricity generation from wind and solar plants (dark blue), the amount that would have been generated if reported curtailment had not taken place (light blue) and the level expected if the rate of curtailment had stayed the same (mid-blue).
In total, wind and solar could have generated an extra 170TWh of electricity in the first quarter of 2026, if the rate of curtailment had not gone up in the preceding years. This is more than the total power generation of France over the same period.
The largest reductions in capacity factors, after controlling for variations in weather conditions, came from Inner Mongolia, Xinjiang and Liaoning. In these northern provinces, the heating season is a challenging time for grid managers due to inflexible operation of plants that provide both heat and power.
More broadly, the key reason for curtailment is inflexible grid management. Flexible operation of coal and gas-fired power plants could very substantially increase the amount of solar and wind power the grid can accommodate.
Yet currently, coal-fired power generation is largely operated via medium- and long-term contracts to supply fixed amounts of electricity at fixed prices, meaning there is no incentive for adjustments in output to make space for solar and wind.
Similarly, electricity trading between provinces is predominantly contracted annually, preventing the variable output of solar and wind from being transmitted between jurisdictions in real time.
These issues have a clear impact on the amount of wind and solar that is curtailed. For example, power-system modeling carried out for the year 2023 indicates that flexible power-grid operation would have essentially eliminated the need for curtailment.
The government has also recognised solar and wind curtailment as one of the central challenges of the energy transition.
Recent policies have called for increased inter-province trading and improved flexibility of coal-power plants as the solutions, implicitly recognising these as key issues to address.
Recent large increases in storage capacity, including pumped hydro and batteries, should have improved the integration of wind and solar into the grid. But there is a lack of incentives for storage operators that limits the benefits the system can derive from the technology.
The government has implicitly recognised this and called for establishing electricity pricing that enables energy storage to “participate fairly”.
Meanwhile, China’s new renewable-pricing rules, which shifted existing solar and wind plants to selling electricity on the market, rather than being compensated directly by the grid operator, does not seem to have reduced curtailment so far.
Most provinces only finalised their plans for implementing the policy in late 2025, which left little time for the market and operators to adapt.
China is aiming to build a “new type power system”, capable of integrating large amounts of wind and solar into the grid by 2027. In the meantime, the government has also called for “reasonably pacing” utility-scale “new energy” capacity additions to match the pace at which provinces think they are able to improve the “regulation capacity” of their grids.
How the Hormuz crisis is affecting China’s energy sector
China’s energy system has started, since March, to adjust to the surge in oil and gas prices triggered by the closure of the strait of Hormuz. There have been sharp reductions in oil imports, the share of gas in thermal power generation and in oil-based chemical production.
The consumption of gas fell overall in March, even as consumption in the power sector increased. The power sector fuel mix shifted from gas to coal, but the increase in overall thermal power generation still pushed gas use up in the sector.
High gas prices had already been straining household finances before the current crisis. Millions of households were shifted from coal stoves to gas-based heating as a part of efforts to tackle air pollution during the past decade. However, the gas-price subsidies created to enable this shift have expired in recent years, leading to a rise in heating bills.
China’s oil imports started falling sharply immediately after oil prices surged, with net imports falling even further as exports were restricted. The fall has continued into May, with shipments falling by over 40% year-on-year in the first three weeks of the month.
In the first quarter of the year, state-owned oil major Sinopec reported oil product sales up 4.8%. Apparent consumption of oil products had increased 5.5% in January-February, but fell -0.3% in March, indicating an early impact of the price surge, although the late timing of the Chinese New Year also had an effect.
Electric vehicles have continued to gain market share in 2026, reaching 53% of vehicle sales in April, up from 47% a year ago.
Electricity demand for EV charging grew over 50% year-on-year in March. The large number of plug-in hybrid vehicles on the road means that drivers can switch from petrol to power quickly when there is more of an incentive to do so.
Moreover, 24% of highway trips during the 1 May holiday were made by EVs, even though they only make up 15% of all registered cars. This shows that EVs tend to be driven more than average, making a bigger dent in oil use than their share in the fleet would suggest.
Crude oil processing volumes fell by 2% in March and 6% in April, after growth in January-February. Plastics output growth moderated in March and turned into a decline in April.
The increase in oil prices has boosted the profitability of the highly carbon-intensive coal-to-chemicals industry. There has also been speculation that the industry would have forcefully increased output in response to the Hormuz crisis, enabling China to cut back on oil use. The industry was, however, already operating at high capacity utilisation before the current crisis, reported at an average of 87% in the first half of 2025. This means there was little headroom in the sector to raise output in the short term.
Coal use in the chemical industry increased 19% in January-February and 22% in March, showing a rapidly rising trend, but no step change after the start of the crisis.
The global fossil-fuel crisis is also affecting China’s clean-energy industry through overseas demand. Exports of solar, batteries and EVs recorded 56% growth year-on-year in the first quarter, reaching $55bn. This increase was partially driven by front-loading of shipments ahead of changes to tax rebates to solar and battery exports at the end of March, but the value of exports also grew 38% in April, an indication of strong underlying demand.
Implications of the crisis for China’s transition
The oil-and-gas crisis represents an opportunity for both clean energy and coal. The economics of electrification and clean-energy production, as well as of domestic coal production, have improved dramatically as imported fossil fuels have become more expensive.
At least as importantly, the closure of the strait of Hormuz and the resulting global fossil-fuel crisis closely mirror Chinese policymakers’ long-standing concern about reliance on seaborne fossil fuels. This is likely to reinforce their focus on energy security.
The previous fossil-fuel crisis, in 2021-2022, led to a new wave of coal-power plants, coal mines and coal-to-chemicals plants being built in China.
This time around, any expansion in coal mining is expected to be limited, both by the government’s “anti-involution” drive, which aims to stem harmful price competition, as well as by the carbon constraints in China’s climate goals.
Domestic coal production fell in the first four months of the year, despite a rise in oil and gas as well as coal prices. Rising coal prices will reduce the profitability of coal-fired power generation, at least for the next few months.
The perceived need for further new coal-power projects is also limited by the fact that, after record additions in 2025, there was still another 206GW of coal-fired capacity under construction in January, due to large volumes of permitting during the previous five years.
The energy regulator recently called on provinces to “strictly limit” the addition of new coal-power plants and other “regulating” power capacity in areas with sufficient firm capacity.
There is also a ceiling on the upside for coal in the current crisis, because gas plays a limited role in China’s energy system. This leaves little space for replacing gas with coal.
The exception is the coal-to-chemicals industry, which can replace oil and gas, albeit at the cost of very high carbon emissions. As a result, investment in the industry will likely get a further boost, even though the economic incentive is lower than it may seem.
While crude oil prices for delivery this summer have increased by more than $40 per barrel since the start of the year, 2030 prices are only up $5. This is a more relevant benchmark, given that a new coal-to-chemicals plant will take several years to build and commission.
The coal-to-chemicals expansion will also be limited by the new system to control carbon emissions. In particular, the requirement for local governments to compensate for carbon emissions from new industrial projects by closing down existing capacity, if these controls are implemented effectively.
Since the previous fossil-fuel crisis, the concept of energy security has become broader, encompassing clean energy and electrification, rather than being limited to coal and fossil fuels. This shift is also clear from how state media has been covering energy security in the wake of the war on Iran.
As such, the oil-and-gas crunch is likely to speed up the electrification of transportation and buildings. It also strengthens the case for “green fuels”, referring to green hydrogen and synthetic gaseous and liquid fuels produced from it, which are an important priority in the new five-year plan.
Solar and wind also become more attractive, economically and politically, as a result of the crisis. The upside may be limited by the dominant narrative that they have grown faster than the grid can manage, rather than being limited by institutional constraints. Nevertheless, they will benefit from fossil fuels – including coal – becoming more expensive and volatile.
Still, curtailment has become a key issue affecting the pace of China’s energy transition. It both reduces the immediate benefits of clean energy and undermines further investment in clean capacity, by increasing investment risks and cutting into returns.
The flipside of the current rise in curtailment is that when the installed wind, solar and energy storage capacity is put to full use, the supply of clean energy will increase substantially.
As noted, a key priority for the government in the next few years is to build a “new type of power system”, capable of integrating large amounts of variable renewable capacity.
The balance between how much the current crisis benefits coal or clean energy will depend on implementation of key climate and energy provisions in the 15th five-year plan.
If power-system reforms that benefit solar, wind and storage are implemented, while carbon-emission controls limit the expansion of coal-to-chemicals, then China is likely to follow a lower-CO2 emission trajectory than expected before the crisis.
About the data
Data for the analysis was compiled from the National Bureau of Statistics of China, National Energy Administration of China, China Electricity Council and China Customs official data releases, as well as from industry data provider WIND Information and from Sinopec, China’s largest oil refiner.
Electricity generation from wind and solar, along with thermal power breakdown by fuel, was calculated by multiplying power generating capacity at the end of each month by monthly utilisation, using data reported by China Electricity Council through Wind Financial Terminal.
Total generation from thermal power and generation from hydropower and nuclear power were taken from National Bureau of Statistics monthly releases.
Monthly utilisation data was not available for biomass, so the annual average of 52% for 2023 was applied. Power-sector coal consumption was estimated based on power generation from coal and the average heat rate of coal-fired power plants during each month, to avoid the issue with official coal consumption numbers affecting recent data.
CO2 emissions estimates are based on National Bureau of Statistics default calorific values of fuels and emissions factors from China’s latest national greenhouse gas emissions inventory, for the year 2021. The CO2 emissions factor for cement is based on annual estimates up to 2024.
For oil, apparent consumption of transport fuels – diesel, petrol and jet fuel – is taken from Sinopec quarterly results, with monthly disaggregation based on production minus net exports. The consumption of these three fuels is labeled as oil product consumption in transportation, as it is the dominant sector for their use.
Apparent consumption of other oil products is calculated from refinery throughput, with the production of the transport fuels and the net exports of other oil products subtracted.
Estimated non-energy use of fossil fuels is subtracted from total chemical industry fossil fuel consumption, and process emissions are calculated based on fossil fuel consumption with carbon retained in products subtracted. Emissions from the incineration of plastics are based on a peer-reviewed estimate of plastics incineration in 2022, combined with growth rates in the overall power generation from waste-to-energy plants. Metals industry process emissions are calculated using industrial output data and IPCC default emission factors.
Reported curtailment, and capacity utilisation in the absence of reported curtailment, is calculated as the complement of the “offtake rates” (利用率) reported by National New Energy Consumption Monitoring and Early Warning Center monthly by province for solar and wind.
Total curtailment is estimated by comparing solar and wind capacity utilisation predicted based on weather conditions, and in the absence of curtailment, to reported utilisation. Utilisation is predicted by fitting regression models to reported monthly utilisation and weather conditions in 2020-2023.
Weather data used for predicting utilisation are hourly wind speed, temperature, solar irradiation and humidity at solar and wind power plant locations in each province from NASA Power and CFSv2. Locations are taken from Global Energy Monitor data.
The post Analysis: China’s CO2 climbs 2% in early 2026 due to ‘wasted’ wind and solar appeared first on Carbon Brief.
Analysis: China’s CO2 climbs 2% in early 2026 due to ‘wasted’ wind and solar
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.
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
As governments at the UN seek ways to prevent the US from unilaterally mining the deep ocean floor for critical minerals, the latest UN seabed talks launched “long” processes that would seek to challenge Washington’s approach.
The International Seabed Authority (ISA), the UN body regulating the deep ocean floor, held annual three-week talks ending on Friday. The discussions come as the US – which is not a member country – moved forward in its unilateral deep-sea mining push, and as mining companies applying for American permits fought back a UN inquiry into their behaviour.
The Trump administration and mining frontrunners, among them Canadian firm The Metals Company (TMC), want to mine a huge area of the Pacific Ocean known as the Clarion-Clipperton Zone. Although it holds deposits of mangenese, nickel and rare earths – key for military use and clean energy components – it is also an unexplored ecosystem with thousands of unnamed species.
The meeting, held at ISA headquarters in Jamaica’s capital Kingston, ended with no immediate breakthroughs. Instead, it started long processes that seeks to hold mining firms and the US accountable, according to ocean governance expert Pradeep Singh, from the Oceano Azul Foundation.
“It shows some level of maturity as well as understanding from member states that this is a long process that requires policy discussions that might not be resolved by acting right away without considerate thought” he said.
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Countries have begun consultations on whether to request an advisory opinion from the International Tribunal for the Law of the Sea (ITLOS), which would seek to clarify the legality of the US-issued permits in the Clarion-Clipperton Zone and whether other states should recognise them.
The ISA will also move forward with an inquiry into its contractors, including The Metals Company (TMC). The company tried to prevent this inquiry by suing the ISA at the ITLOS for allegedly acting in bad faith, an argument that the world’s top maritime court rejected.
ISA secretary-general Letícia Carvalho said in her closing remarks that the past year “presented both significant challenges and noteworthy achievements”. Earlier in the talks, she said the agency’s role is “more important than ever” and that resources in the deep seabed are “the common heritage of humankind”.
Advisory opinion on legality of US mining push
Towards the end of the ISA assembly, Carvalho submitted a draft text to countries proposing they request an advisory opinion from the ITLOS, clarifying the legality of the US deep-sea mining push.
The initiative proposed questions to the court, including whether international law backs the principle that the deep seafloor cannot be appropriated by any single country, and whether other governments should avoid recognising any similar effort.
Several nations including the African group, New Zealand, Norway, France, Singapore, Jamaica and Canada argued that while they could back such a proposal, it required careful legal consideration. Some regretted that the note was not sent earlier in the talks.
Russia and China backed the request for an advisory opinion. The Chinese delegation suggested asking whether unilateral actions by non-member states – such as the US – would break international law, and what the consequences of such actions would be.
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By the end of the talks there was no consensus on this proposal. The assembly decided instead to hold consultations led by Malta, and decide on whether to request an advisory opinion by next year’s meeting.
“They are not rushing into this,” Singh explained. “It also seems that they are not feeling immediately threatened at this stage, and that there are still some things that could be done to find a way forward and perhaps persuading the US from acting unilaterally.”
Growing call for deep-sea mining moratorium
Activists were also critical of the ISA deciding to renew one of TMC’s exploration licenses in the Clarion-Clipperton Zone, which expired last month. Haldis Helle, ocean campaigner at Greenpeace, said this was a “reward” for TMC despite “their clear disregard for international law”.
But Singh argued that the renewal was “not an endorsement to act unilaterally” but an effort from countries to make the “whole decision-making including the inquiry process robust”, without showing signs of any bias.
Instead, campaigners highlighted a growing call for a moratorium on deep-sea mining, which seeks to halt all activity until enough scientific evidence can show that it is not harmful for marine wildlife. The initiative is now backed by 46 governments, with Mauritius, Mozamboque and the Republic of Congo becoming the latest supporters.
“The lesson from the past three weeks is clear: only a pause on exploitation, now backed by over a quarter of ISA member states, can deliver the legal certainty this moment demands and rein in a situation being driven out of control by a handful of reckless companies“, said Sofia Tsenikli, global campaign director at the Deep-Sea Conservation Coalition (DSCC).
The post Governments weigh response to US going alone on deep-sea mining appeared first on Climate Home News.
Governments weigh response to US going alone on deep-sea mining
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