Hydrogen emissions are ‘supercharging’ the warming impact of methane
The warming impact of hydrogen has been “overlooked” in projections of climate change, according to authors of the latest “global hydrogen budget”.

The study, published in Nature, is the most comprehensive analysis yet of the global hydrogen cycle, showing how the gas moves between the atmosphere, land and ocean.

Hydrogen has long been recognised as a clean alternative to fossil fuels and an important component of the green energy transition.

However, while hydrogen is not itself a greenhouse gas, rising emissions are “supercharging” the warming effect of methane, the authors say.

Increasing levels of atmospheric hydrogen have led to “indirect” warming of 0.02C over the past decade, the study finds.

The authors say that limiting leaks from future hydrogen fuel projects and rapidly cutting methane emissions will be key to securing benefits from hydrogen as a clean-burning alternative to oil and gas.

The international team of scientists behind the study also produce the annual “global carbon budget”, which saw its 20th edition published last month.

‘Supercharging’ methane

Hydrogen is the lightest and most abundant element in the universe. It is also an explosive gas that contains more energy per unit of weight than fossil fuels.

The gas has long been recognised as a clean alternative to fossil fuels, because it only emits water when burned.

There are many ways to produce hydrogen. It is typically generated in a carbon-intensive process that relies on fossil fuels. However, renewable energy can be used to produce “green hydrogen” with near-zero carbon emissions.

Hydrogen “indirectly” heats the atmosphere through its interactions with other gases. This warming is mainly due to interplay between hydrogen and methane – a potent greenhouse gas that is the second biggest contributor to human-caused global warming after CO2.

This interplay involves molecules in the atmosphere called hydroxyl radicals. These naturally occurring molecules are known as the atmosphere’s “detergents” because they react with certain greenhouse gases, such as methane, converting them into other compounds that do not warm the planet.

Prof Rob Jackson is a scientist at Stanford University and an author on the study. He explains that hydrogen also reacts with hydroxyl radicals, effectively “using up” these detergents and leaving less to react with methane.

This effectively “extends the lifetime” of methane in the atmosphere, Jackson tells Carbon Brief, leading to higher concentrations and greater warming.

There is also a reciprocal effect, where more methane in the atmosphere leads to more hydrogen. This occurs because methane reacts with oxygen in the atmosphere in a process called “oxidation”, which produces hydrogen.

Jackson tells Carbon Brief that interactions between hydrogen and methane have “not really been considered in climate circles”, adding:

“I think people don’t realise that the dominant source of hydrogen in the world today is methane in the atmosphere.”

Overall, the study estimates that increasing levels of hydrogen in the atmosphere led to global warming of 0.02C over 2010-20. This climate impact has been “overlooked”, the researchers say in a press release.

Jackson te[...]

lls Carbon Brief that although this level of warming “looks fairly small”, it is still “comparable” to the warming caused by emissions of individual countries, such as France.

The hydrogen cycle

The global hydrogen budget brings together a range of observed data and models to quantify sources of hydrogen emissions as well as “sinks”, which absorb the gas from the atmosphere.

The authors find that hydrogen levels in the atmosphere increased from 523 parts per billion (ppb) in 1992 to 543ppb in 2020.

The graphic below shows the main sources (up arrows) and sinks (down arrows) of hydrogen over 2010-20.
https://www.carbonbrief.org/wp-content/uploads/2025/12/Screenshot_2025-12-17_at_11.39.09.png Sources and sinks of hydrogen over 2010-20. Source: Ouyang et al (2025).
As the figure shows, the largest single contributor to rising hydrogen emissions over 2010-20 is from the oxidation of human-produced methane. Methane emissions are on the rise due to human activity, such as from the fossil fuel industry, livestock and waste.

According to the study, 56% of atmospheric hydrogen over 2010-20 was caused by the oxidation of methane and non-methane volatile organic compounds (NMVOCs) reacting with oxygen to produce hydrogen.

(NMVOCs are chemicals that are released naturally from vegetation and more rapidly during wildfires. Human-produced emissions of NMVOCs – for example, from oil refineries or car tailpipes – are also on the rise, according to the study.)

The study also points to leakage from industrial hydrogen production as another driver of rising atmospheric hydrogen levels.

Jackson tells Carbon Brief that hydrogen leakage is on the rise “not because manufacturing is getting dirtier, but because we’re making more hydrogen from coal and natural gas”.

Hydrogen can also be produced as an unintentional byproduct from the combustion of fossil fuels. The study finds that these emissions of hydrogen are decreasing.

At the same time, natural sources of hydrogen emissions have not shown any increasing or decreasing trend over time, the authors say.

One of the largest natural sources of hydrogen is through “nitrogen fixing” – a chemical process in which nitrogen is converted into ammonia, which releases hydrogen as a byproduct. This process locks down nitrogen into the soil and ocean, where it is used by plants and algae to grow.

Meanwhile, hydrogen sinks have “increased in response to rising atmospheric hydrogen” over the past three decades, the study says.

Nearly three-quarters of the global hydrogen sink comes from hydrogen getting trapped in soil – for example, by microbes taking in hydrogen to use for energy, or hydrogen seeping into the soil through diffusion.

Dr Zutao Ouyang is an assistant professor at the University of Harvard and lead author on the study. He tells Carbon Brief that soil uptake is “the main mechanism removing hydrogen from the atmosphere”, but adds that it also has “the greatest uncertainty” because there is “not much long-term data” on this component of the hydrogen budget.

Mapped

Drawing on data including observational measurements and emissions inventories, the authors map the sources and sinks of hydrogen and their relative strength.

The maps below show the sources (top) and sinks (bottom) over 1990-2020, where darker colours indicate a stronger source or sink.
https://www.carbonbrief.org/[...]

wp-content/uploads/2025/12/Screenshot_2025-12-17_at_11.39.44-1008x1024.png Sources (top) and sinks (bottom) of hydrogen over 1990-2020. Source: Ouyang et al (2025).
The largest “hotspots” for hydrogen emissions are in “south-east and east Asia”, according to the research. More widely, it says that “tropical regions” contribute about 60% of total hydrogen emissions.

The authors explain that these “hotspots” occur because the oxidation of methane and NMVOCs – processes that happen in the atmosphere and produce hydrogen as a byproduct – happen more quickly at higher temperatures.

They also find that these regions have more vegetation, which leads to higher NMVOC emissions.

For emissions related to human activity, east Asia and North America “contributed the most hydrogen emissions from fossil fuel combustion”, the study says, due to the “intensive fossil fuel use”.

Hydrogen emissions due to nitrogen fixation – when plants draw down nitrogen and release hydrogen as a byproduct – are highest in South America. The report links these emissions to the region’s “extensive cultivation” of crops such as soybeans and peanuts. Dr Maria Sand is a senior researcher at CICERO and was not involved in the study. She tells Carbon Brief that the paper “provides a valuable and much-needed assessment of the global hydrogen budget”. She adds:

“By better constraining the sources and sinks of hydrogen, this study helps reduce the uncertainty in the climate impact [of hydrogen].” Dr Nicola Warwick is a researcher at the National Centre for Atmospheric Science and assistant research professor at the University of Cambridge. She tells Carbon Brief that the study “provides an important update to our understanding of the atmospheric hydrogen budget by better constraining the key sources and sinks of hydrogen”.

She adds that better understanding of hydrogen uptake by soil – including how it responds to “climate-driven changes in soil moisture and temperature” – are “essential for reliably assessing the climate impacts of any future changes in hydrogen emissions”.

Study author Jackson tells Carbon Brief that he hopes the study will “prompt people to evaluate some of these emissions and sources and sinks in new ways and new places”. Hydrogen economy

In the pursuit of net-zero, hydrogen may play an increasingly important role in the global energy system.

There are many ways to produce hydrogen gas. Most hydrogen is currently generated through a process called steam reforming, which brings together fossil gas and steam to produce hydrogen, with CO2 as a by-product.

According to the study, more than 90% of hydrogen produced today uses this “carbon-intensive” method.

However, electricity can be used to split water into hydrogen and oxygen atoms, in a process called electrolysis. If renewable energy is used, hydrogen can be produced and consumed with near-zero carbon emissions.

Hydrogen can be stored, liquified and transported via pipelines, trucks or ships. It can be used to make fertiliser, fuel vehicles, heat homes, generate electricity or drive heavy industry.

This potential hydrogen “economy” is shown in the graphic below. The illustrations, with numbered captions from one to three, show how hydrogen could be made, moved and used

The graphic below, from Carbon Brief’s explainer, illustrates the elements of a potential hydrogen economy.
https://www.carbonbrief.org/wp-content/uploads/2025/12/Screenshot-2025-12-17-at-9.58.45-AM.png Source: Carbon Brief (<a href='https://www.carbonbrief.org/[...]

in-depth-qa-does-the-world-need-hydrogen-to-solve-climate-change/'>2020).
Jackson tells Carbon Brief that, in his opinion, hydrogen is a “brilliant” choice to replace fossil fuels on-site, for industries such as steel manufacturing. However, he says he is “concerned” about “a hydrogen economy that distributes hydrogen around the world in millions of users”, because there is potential for lots of the gas to leak.

He adds:

“We know that methane leakage is bad. Hydrogen is a smaller molecule than methane. So wherever you have methane and hydrogen together, if methane leaks, hydrogen is likely to leak even more.”

The authors model hydrogen emissions under a range of future warming scenarios over the coming century.

They find that in “low-warming scenarios with high hydrogen usage”, methane emissions are low, limiting the formation of hydrogen via the oxidation of methane. In this instance, changes in atmospheric hydrogen levels depend strongly on leakage.

Meanwhile, in higher-warming scenarios, the authors find that hydrogen use is “relatively low”, but methane emissions remain “largely unmitigated”. In this instance, they find that the additional hydrogen formed through the oxidation of methane can outweigh hydrogen released through leaks.

Overall, the authors suggest that hydrogen could cause additional warming of 0.01-0.05C by the year 2100. Study author Zutao tells Carbon Brief that this additional warming was not included in the climate projections in the last assessment report from the Intergovernmental Panel on Climate Change.
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The post Hydrogen emissions are ‘supercharging’ the warming impact of methane appeared first on Carbon Brief.

Ayesha Tandon

Source: https://www.carbonbrief.org/?p=60618

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Guest post: How to steer EVs towards the road of ‘mass adoption’
Electric vehicles (EVs) now account for more than one-in-four car sales around the world, but the next phase is likely to depend on government action – not just technological change.

That is the conclusion of a new report from the Centre for Net Zero, the Rocky Mountain Institute and the University of Oxford’s Environmental Change Institute.

Our report shows that falling battery costs, expanding supply chains and targeted policy will continue to play important roles in shifting EVs into the mass market.

However, these are incremental changes and EV adoption could stall without efforts to ensure they are affordable to buy, to boost charging infrastructure and to integrate them into power grids.

Moreover, emerging tax and regulatory changes could actively discourage the shift to EVs, despite their benefits for carbon dioxide (CO2) emissions, air quality and running costs.

This article sets out the key findings of the new report, including a proposed policy framework that could keep the EV transition on track.

A global tipping point

Technology transformations are rarely linear, as small changes in cost, infrastructure or policy can lead to outsized progress – or equally large reversals.

The adoption of new technologies tends to follow a similar pathway, often described by an “S-curve”. This is divided into distinct phases, from early uptake, with rapid growth from very low levels, through to mass adoption and, ultimately, market saturation.

However, technologies that depend on infrastructure display powerful “path-dependency”, meaning decisions and processes made early within the rollout can lock in rapid growth, but equally, stagnation can also become entrenched, too.

EVs are now moving beyond the early-adopter phase and beginning to enter mass diffusion. There are nearly 60m on the road today, according to the International Energy Agency, up from just 1.2m a decade ago.

Technological shifts of this scale can unfold faster than expected. Early in the last century in the US, for example, millions of horses and mules virtually disappeared from roads in under three decades, as shown in the chart below left.

Yet the pace of these shifts is not fixed and depends on the underlying technology, economics, societal norms and the extent of government support for change. Faster or slower pathways for EV adoption are illustrated in the chart below right.
https://www.carbonbrief.org/wp-content/uploads/2025/12/Screenshot_2025-12-18_at_10.08.59-scaled.png Left: The S-curve from horses to cars. Right: The predicted shift from ICE to EVs. Note that S-curves present technology market shares from fixed saturation levels to show the shape of diffusion, rather than absolute numbers; Cars were both a substitute for, and additional to, horses. Sources: Grubler (1999), Technology and Global Change (left); Rocky Mountain Institute, IEA data (2023) (right).
Internal combustion engine (ICE) vehicles did not prevail in becoming the dominant mode of transport through technical superiority alone. They were backed by massive public investment in roads, city planning, zoning and highway expansion funded by fuel taxes.

Meanwhile, they faced few penalties fo[...]

r pollution and externalities, benefitting from implicit subsidies over cleaner alternatives. Standardisation, industrial policy and wartime procurement further entrenched the ICE.

EVs are well-positioned to follow a faster trajectory, as they directly substitute ICE vehicles while being cleaner, cheaper and quieter to run.

Past transitions show that like-for-like replacements – such as black-and-white to colour TVs – tend to diffuse faster than entirely novel products.

Late adopters also benefit from cost reductions and established norms. For example, car ownership took 60 years to diffuse across the US, but just 20 years in parts of Latin America and Japan.

In today’s globalised economy, knowledge, capital and supply chains travel faster still. Our research suggests that the global EV shift could be achieved within decades, not half a century.

Yet without decisive policy, investment and coordination, feedback loops could slow, locking in fossil-fuel dependence.

Our research suggests that further supporting the widespread deployment of EVs hangs on three interlinked actions: supporting adoption; integrating with clean electricity systems; and ensuring sustainability across supply chains and new mobility systems.

Closing the cost gap

EVs have long offered lower running costs than ICE vehicles, but upfront costs – while now cost-competitive in China, parts of Europe and in growing second-hand markets – remain a major barrier to adoption in most regions.

While battery costs have fallen sharply – lithium-ion battery packs fell by 20% in 2024 alone – this has not fully translated into lower retail vehicle prices for consumers.

In China, a 30% fall in battery prices in 2024 translated into a 10% decline in electric SUV prices. However, in Germany, EV retail prices rose slightly in 2024 despite a 20% drop in battery costs.

These discrepancies reflect market structures rather than cost fundamentals. Our report suggests that a competitive EV market, supported by transparent pricing and a strong second-hand sector, can help unlock cost parity in more markets.

Beyond the sale of EVs, government policy around running costs, such as fuel duty, has the potential to disincentivse EV adoption.

For example, New Zealand’s introduction of road-pricing for EVs contributed to a collapse in registrations from nearly 19% of sales in December 2023 to around 4% in January 2024.

EV-specific fees have also been introduced in a number of US states. Last month, the UK also announced a per-mile charge for EVs – but not ICEs – from 2028.

Addressing the loss of fuel-duty revenue as EVs replace ICE vehicles is a headache for any government seeking to electrify mobility.

However, to avoid slowing diffusion, new revenues could be used to build out new charging infrastructure, just as road-building was funded as the ICE vehicle was scaling up.

While subsidies to support upfront costs can help enable EV adoption, the best approach to encouraging uptake is likely to shift once the sector moves into a phase of mass diffusion.

Targeted support, alongside innovative financing models to broaden access, from blended finance to pay-as-you-drive schemes, could play a greater role in ensuring lower-income drivers an[...]

d second-hand buyers are not left behind.

Mandates as engines of scale

Zero-emission vehicle (ZEV) mandates and ICE phase-out deadlines can reduce costs more effectively than alternatives by guaranteeing market scale, our research finds, reducing uncertainty for automakers and pushing learning rates forward through faster production.

California’s ZEV mandate was one of the first in the 1990s, a policy that has since been adopted by ten other US states and the UK.

China’s NEV quota system has produced the world’s fastest-growing EV market, while, in Norway, clear targets and consistent incentives mean EVs now account for nearly all of new car sales. These “technology-forcing” policies have proved highly effective.

Analyses consistently show that the long-run societal benefits of sales mandates for EVs far outweigh their compliance costs.

For example, the UK’s ZEV mandate has an estimated social net present value of £39bn, according to the government, driven largely by emissions reductions and lower running costs for consumers.

Benefits can also extend beyond national borders. For example, California’s “advanced clean cars II” regulations – adopted by a number of US states and an influence on other countries – have been instrumental in compelling US automakers to develop and commercialise EVs, which can, in turn, trigger innovation and scale to reduce costs worldwide.

Research suggests that, where possible, combining mandates and incentives creates further synergies: mandates alleviate supply-side constraints, making subsidies more effective on the demand side.

Public charging: a critical bottleneck

Public charging is one of the most significant impediments to EV adoption today.

Whereas EVs charged at home are substantially cheaper to run than ICE vehicles, higher public charging costs can erase this benefit – in the UK, this can be up to times the home equivalent.

While most homes in the UK, for example, do have access to off-street parking, there are large swathes of low-income and urban households without access to private driveways. For these households, a lack of cheap public charging has been described as a de facto “pavement tax”, which is disincentivising EV adoption and resulting in an inequitable transition.

Our research shows that a dual-track charging strategy could help resolve the situation. Expanding access to private charging – through cross-pavement cabling, “right-to-charge” legislation for renters and planning mandates for new developments could be combined with  strategic investment in public charging, to overcome the “chicken-and-egg” problem for investors uncertain about future EV demand.

Meanwhile, “smart charging” in public [...]

settings  – where EV demand is matched with cheaper electricity supply – can also help close the affordability gap, by delivering cheap off-peak charging that is already available to those charging at home.

The Centre for Net Zero’s research shows that drivers respond to dynamic pricing outside of the convenience of their homes, which reduces EV running costs below those of petrol cars.

The figure below shows that, while the level of discount being offered had the strongest impact, lower-income areas showed the largest behavioural response, indicating that they may stand to gain the most from a rollout of such incentives.
https://www.carbonbrief.org/wp-content/uploads/2025/12/Lower-income_households_respond_more_strongly_to_price_incentives_1.png Impact on charging behaviour from a “green message”, 15% or 40% discounts, according to the average disposable income in the area. Source: Centre for Net Zero (2025)
Our research suggests that policymakers could encourage this type of commercial offering by creating electricity markets with strong price signals and mandating that these prices are transparent to consumers.

Integrating with clean electricity grids

Electrification is central to decarbonising the world’s economies, meaning that sufficient capacity on electricity networks is becoming a key focus.

For the rollout of EVs, pressure will be felt most on low-voltage “distribution” networks, where charging is dispersed and tends to follow existing peaks and troughs in domestic demand.

Rather than responding to this challenge by just building out the grid – with the corresponding economic and political implications – making smart charging the norm could help mitigate pressure on the network.

Evidence from the Centre for Net Zero’s trials shows that AI-managed charging can shift EV demand off-peak, reducing residential peak load by 42%, as shown in the chart below.

Additionally, the amount of time when EVs are plugged in but not moving is often substantial, giving networks hours each day in which they can shift charging, targeting periods of low demand or high renewable output.
https://www.carbonbrief.org/wp-content/uploads/2025/12/Shifting_EV_demand_can_reduce_loads_during_peak_periods_by_42_.png Average hourly consumption of electricity (kWh) across different hours of the day, showing baseline consumption (grey) and that with an EV tariff (navy). Source: Centre for Net Zero (2025)
The system value of this flexible charging is significant. In the UK, managed charging could absorb 15 terrawatt hours (TWh) of renewable electricity that would otherwise be curtailed by 2030 – equivalent to Slovenia’s entire annual consumption.

For these benefits to be realised, our research suggests that global policymakers may need to mandate interoperability across vehicles, chargers and platforms, introduce dynamic network charges that reflect local grid stress and support AI-enabled automation.

Bi-directional charging – which allows EVs to export electricity to the grid, becoming decentralised, mobile storage units – remains underexploited. T[...]

his could allow EVs to contribute to the capacity of the grid, helping with frequency and providing voltage support at both local and system levels.

The nascency of such vehicle-to-grid (V2G) technology means that penetration is currently limited, but there are some markets that are further ahead.

For example, Utrecht is an early leader in real-world V2G deployment in a context of significant grid congestion, while Japan is exploring the use of V2G for system resilience, providing backup power during outages. China is also exploring V2G systems.

Our research shows that if just 25% of vehicles across six major European nations had V2G functionality, then the theoretical total capacity of the connected vehicles would exceed each of those country’s fossil-fuel power fleet.

Mandating V2G readiness at new chargepoints, aligning the value of exports with the value to the system and allowing aggregators to pool capacity from multiple EVs, could all help take V2G from theory to reality. A sustainable EV system

It is important to note that electrification alone does not guarantee sustainability.

According to Rocky Mountain Institute (RMI) analysis, the total weight of ore needed to electrify the world’s road transport system is around 1,410mtonnes (Mt). This is 40% less than the 2,150Mt of oil extracted every year to fuel a combustion-based system. EVs concentrate resource use upfront, rather than locking in fossil-fuel extraction.

Moreover, several strategies can reduce reliance on virgin minerals, including recycling, new chemistries and improved efficiency.

Recycling, in particular, is progressing rapidly. Some 90% of lithium-ion batteries could now be recycled in some regions, according to RMI research. Under an accelerated scenario, nearly all demand could be met through recycling before 2050.

Finally, while our report focuses largely on EVs, it is important to highlight that they are not a “silver bullet” for decarbonising mobility.

Cities such as Seoul and New York have demonstrated that micromobility, public transport and street redesign can cut congestion, improve health and reduce the number of overall vehicles required.

Better system design reduces mineral demand, lowers network strain and broadens access. The ‘decision decade’ ahead

Policy decisions made today will determine whether EVs accelerate into exponential growth or stall.

Our research suggests that governments intent on capturing the economic and environmental dividends of electrified mobility are likely to need coherent, cross-cutting policy frameworks that push the market up the steep climb of the EV S-curve.
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The post Guest post: How to steer EVs towards the road of ‘mass adoption’ appeared first on Carbon Brief.

Carbon Brief Staff

Source: https://www.carbonbrief.org/?p=60642

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DeBriefed 19 December 2025:  EU’s petrol car U-turn; Trump to axe ‘leading’ research lab; What climate scientists are reading
Welcome to Carbon Brief’s DeBriefed.
An essential guide to the week’s key developments relating to climate change.

This week

EU easing up

HITTING THE BREAKS: The EU “walked back” its target to ban the sale of petrol and diesel cars by 2035, “permitting some new combustion engine cars”, reported Agence-France Presse. Under the original plan, the bloc would have had to cut emissions entirely by 2035 on new vehicles, but will now only have to cut emissions by 90% by that date, compared to 2021 levels. However, according to the Financial Times, some car manufacturers have “soured” on the reversal.

ADJUSTING CBAM: Meanwhile, the Financial Times reported that the EU is making plans to “close loopholes” in the bloc’s carbon border adjustment mechanism (CBAM) before it goes into effect in January. CBAM is set to be the world’s first carbon border tax and has drawn ire from key trading partners. The EU has also finalised a plan to delay its anti-deforestation legislation for another year, according to Carbon Pulse.

Around the world
* NCAR NO MORE: The Trump administration is moving to “dismantle” the National Center for Atmospheric Research in Colorado, said USA Today, describing it as “one of the world’s leading climate research labs”.
* DEADLY FLOODS: The deadliest flash flooding in Morocco in a decade killed “at least” 37 people, while residents accused the government of “ignoring known flood risks and failing to maintain basic infrastructure”, reported Radio France Internationale.
* FAILING GRADE: The past year was the “warmest and wettest” ever recorded in the Arctic, with implications for “global sea level rise, weather patterns and commercial fisheries”, according to the US National Oceanic and Atmospheric Administration’s 2025 Arctic report card, covered by NPR.
* POWER TO THE PEOPLE: Reuters reported that Kenya signed a $311m agreement with an African infrastructure fund and India’s Power Grid Corporation for the “construction of two high-voltage electricity transmission lines” that could provide power for millions of people.
* BP’S NEW EXEC: BP has appointed Woodside Energy Group’s Meg O’Neill as its new chief executive amid a “renewed push to…double down on oil and gas after retreating from an ambitious renewables strategy”, said Reuters.
29

The number of consecutive years in which the Greenland ice sheet has experienced “continuous annual ice loss”, according to a Carbon Brief guest post.
Latest climate research
* Up to 4,000 glaciers could “disappear” per year during “peak glacier extinction”, projected to occur sometime between 2041 and 2[...]

055 | Nature Climate Change
* The rate of sea level rise across the coastal US doubled over the past century | AGU Advances
* Repression and criminalisation of climate and environmentally focused protests are a “global phenomena”, according to an analysis of 14 countries | Environmental Politics
(For more, see Carbon Brief’s in-depth daily summaries of the top climate news stories on Monday, Tuesday, Wednesday, Thursday and Friday.)

Captured
https://www.carbonbrief.org/wp-content/uploads/2025/12/image-1024x720.png
The latest coal market report from the International Energy Agency said that global coal use will reach record levels in 2025, but will decline by the end of the decade. Carbon Brief analysis of the report found that projected coal use in China for 2027 has been revised downwards by 127m tonnes, compared to the projection from the 2024 report – “more than cancelling out the effects of the Trump administration’s coal-friendly policies in the US”.

Spotlight

What climate scientists are curious about

This week, Carbon Brief spoke to climate scientists attending the annual meeting of the American Geophysical Union in New Orleans, Louisiana, about the most interesting research papers they read this year.

Their answers have been lightly edited for length and clarity.

Dr Christopher Callahan, assistant professor at Indiana University Bloomington

The most interesting research paper I read was a simple thought experiment asking when we would have known humans were changing the climate if we had always had perfect observations. The authors show that we could have detected a human influence on the climate as early as the 1880s, since we have a strong physical understanding of how those changes should look. This paper both highlights that we have been discernibly changing the climate for centuries and emphasises the importance of the modern climate observing network – a network that is currently threatened by budget cuts and staff shortages.

Prof Lucy Hutyra, distinguished professor at Boston University

The most interesting paper I read was in Nature Climate Change, where the researchers looked at how much mortality was associated with cold weather versus hot weather events and found that many more people died during cold weather events. Then, they estimated how much of a protective factor in the urban heat island is on those winter deaths and suggested that the winter benefits exceed the summer risks of mitigating extreme heat, so perhaps we shouldn’t mitigate extreme heat in cities.

This paper got me in a tizzy…It spurred an exciting new line of research. We’ll be publishing a response to this paper in 2026. I’m not sure their conclusion was correct, but it raised really excellent questions.

Dr Kristina Dahl, vice president for science at Climate Central

This year[...]

was when we saw source attribution studies, such as Chris Callahan‘s, really start to break through and be able to connect the emissions of specific emitters…to the impact of those emissions through heat or some other sort of damage function. [This] is really game-changing.

What [Callahan’s] paper showed is that the emissions of individual companies have an impact on extreme heat, which then has an impact on the GDP of the countries experiencing that extreme heat. And so, for the first time, you can really say: “Company X caused this condition which then led to this economic damage.” Dr Antonia Hadjimichael, assistant professor at Pennsylvania State University

It was about interdisciplinary work – not that anything in it is ground-shakingly new, but it was a good conversation around interdisciplinary teams and what makes them work and what doesn’t make them work. And what I really liked about it is that they really emphasise the role of a connector – the scientist that navigates this space in between and makes sure that the things kind of glue together…The reason I really like this paper is that we don’t value those scientists in academia, in traditional metrics that we have. Dr Santiago Botía, researcher at Max Planck Institute for Biogeochemistry

The most interesting paper I’ve read this year was about how soil fertility and water table depth control the response to drought in the Amazon. They found very nicely how the proximity to soil water controls the anomalies in gross primary productivity in the Amazon. And, with that methodology, they could explain the response of recent droughts and the “greening” of the forest during drought, which is kind of a counterintuitive [phenomenon], but it was very interesting. Dr Gregory Johnson, affiliate professor at the University of Washington

This article explores the response of a fairly coarse spatial resolution climate model…to a scenario in which atmospheric CO2 is increased at 1% a year to doubling and then CO2 is more gradually removed from the atmosphere…[It finds] a large release of heat from the Southern Ocean, with substantial regional – and even global – climate impacts. I find this work interesting because it reminds us of the important – and potentially nonlinear – roles that changing ocean circulation and water properties play in modulating our climate.

Cecilia Keating also contributed to this spotlight. Watch, read, listen

METHANE MATTERS: In the Guardian, Barbados prime minister Mia Mottley wrote that the world must “urgently target methane” to avoid the worst impacts of climate change.

CLIMATE WRAPPED: Grist summarised the major stories for Earth’s climate in 2025 – “the good, the bad and the ugly”.

COASTING: On the Coastal Call podcast, a biogeochemist spoke about “coastal change and community resilience” in the eastern US’s Long Island Sound. Coming up
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Analysis: UK renewables enjoy record year in 2025 – but gas power still rises
The UK’s fleet of wind, solar and biomass power plants all set new records in 2025, Carbon Brief analysis shows, but electricity generation from gas still went up.

The rise in gas power was due to the end of UK coal generation in late 2024 and nuclear power hitting its lowest level in half a century, while electricity exports grew and imports fell.

In addition, there was a 1% rise in UK electricity demand – after years of decline – as electric vehicles (EVs), heat pumps and data centres connected to the grid in larger numbers.

Other key insights from the data include:

* Electricity demand grew for the second year in a row to 322 terawatt hours (TWh), rising by 4TWh (1%) and hinting at a shift towards steady increases, as the UK electrifies.
* Renewables supplied more of the UK’s electricity than any other source, making up 47% of the total, followed by gas (28%), nuclear (11%) and net imports (10%).
* The UK set new records for electricity generation from wind (87TWh, +5%), solar (19TWh, +31%) and biomass (41TWh, +2%), as well as for renewables overall (152TWh, +6%).
* The UK had its first full year without any coal power, compared with 2TWh of generation in 2024, ahead of the closure of the nation’s last coal plant in September of that year.
* Nuclear power was at its lowest level in half a century, generating just 36TWh (-12%), as most of the remaining fleet paused for refuelling or outages.

Overall, UK electricity became slightly more polluting in 2025, with each kilowatt hour linked to 126g of carbon dioxide (gCO2/kWh), up 2% from the record low of 124gCO2/kWh, set last year.

The National Energy System Operator (NESO) set a new record for the use of low-carbon sources – known as “zero-carbon operation” – reaching 97.7% for half an hour on 1 April 2025.

However, NESO missed its target of running the electricity network for at least 30 minutes in 2025 without any fossil fuels.

The UK inched towards separate targets set by the government, for 95% of electricity generation to come from low-carbon sources by 2030 and for this to cover 100% of domestic demand.

However, much more rapid progress will be needed to meet these goals.

Carbon Brief has published an annual analysis of the UK’s electricity generation in 2024, 2023, 2021, 2019, 2018, 2017 and 2016.

Record renewables

The UK’s fleet of renewable power plants enjoyed a record year in 2025, with their combined electricity generation reaching 152TWh, a 6% rise from a year earlier.

Renewables made up 47% of UK electricity s[...]

upplies, another record high. The rise of renewables is shown in the figure below, which also highlights the end of UK coal power.

While the chart makes clear that gas-fired electricity generation has also declined over the past 15 years, there was a small rise in 2025, with output from the fuel reaching 91TWh. This was an increase of 5TWh (5%) and means gas made up 28% of electricity supplies overall.

The rise in gas-fired generation was the result of rising demand and another fall in nuclear power output, which reached the lowest level in half a century, while net imports and coal also declined.
https://www.carbonbrief.org/wp-content/uploads/2025/12/UK_renewables_enjoy_record_year_in_2025_E28093_but_gas_power_still_rises.png UK electricity supplies by source 2010-2025, terawatt hours (TWh). Net imports are the sum of imports minus exports. Renewables include wind, biomass, solar and hydro. The chart excludes minor sources, such as oil, which makes up less than 2% of the total. Source: Carbon Brief analysis of data from NESO and DESNZ.
The year began with the UK’s sunniest spring and by mid-December had already become the sunniest year on record. This contributed to a 5TWh (31%) surge in electricity generation from solar power, helped by a jump of roughly one-fifth in installed generating capacity.

The new record for solar power generation of 19TWh in 2025 comes after years of stagnation, with electricity output from the technology having climbed just 15% in five years.

The UK’s solar capacity reached 21GW in the third quarter of 2025. This is a substantial increase of 3 gigawatts (GW) or 18% year-on-year.

These are the latest figures available from the Department for Energy Security and Net Zero (DESNZ). The DESNZ timeseries has been revised to reflect previously missing data.

UK wind power also set a new record in 2025, reaching 87TWh, up 4TWh (5%). Wind conditions in 2025 were broadly similar to those in 2024, with the uptick in generation due to additional capacity.

The UK’s wind capacity reached 33GW in the third quarter of 2025, up 1GW (4%) from a year earlier. The 1.2GW Dogger Bank A in the North Sea has been ramping up since autumn 2025 and will be joined by the 1.2GW Dogger Bank B in 2026, as well as the 1.4GW Sofia project.

These sites were all awarded contracts during the government’s third “contracts for difference” (CfD) auction round and will be paid around £53 per megawatt hour (MWh) for the electricity they generate. This is well below current market prices, which currently sit at around £80/MWh.

Results from t[...]

he seventh auction round, which is currently underway, will be announced in January and February 2026. Prices are expected to be significantly higher than in the third round, as a result of cost inflation.

Nevertheless, new offshore wind capacity is expected to be deliverable at “no additional cost to the billpayer”, according to consultancy Aurora Energy Research.

The UK’s biomass energy sites also had a record year in 2025, with output nudging up by 1TWh (2%) to 41TWh. Approximately two-thirds (roughly 27TWh) of this total is from wood-fired power plants, most notably the Drax former coal plant in Yorkshire, which generated 15TWh in 2024.

The government recently awarded new contracts to Drax that will apply from 2027 onwards and will see the amount of electricity it generates each year roughly halve, to around 6TWh. The government is also consulting on how to tighten sustainability rules for biomass sourcing. Rising demand

The UK’s electricity demand has been falling for decades due to a combination of more efficient appliances and lightbulbs, as well as ongoing structural shifts in the economy.

Experts have been saying for years that at some point this trend would be reversed, as the UK shifts to electrified heat and transport supplies using EVs and heat pumps.

Indeed, the Climate Change Committee (CCC) has said that demand would more than double by 2050, with electrification forming a key plank of the UK’s efforts to reach net-zero.

Yet there has been little sign of this effect to date, with electricity demand continuing to fall outside single-year rebounds after economic shocks, such as the 2020 Covid lockdowns.

The data for 2025 shows hints that this turning point for electricity demand may finally be taking place. UK demand increased by 4TWh (1%) to 322TWh in 2025, after a 1TWh rise in 2024.

After declining for more than two decades since a peak in 2005, this is the first time in 20 years that UK demand has gone up for two years in a row, as shown in the figure below.
https://www.carbonbrief.org/wp-content/uploads/2025/12/UK_electricity_use_grew_by_1__in_2025_after_decades_of_decline_1.png Annual UK electricity demand 2000-2025, terawatt hours (TWh). The truncated y-axis shows recent changes more clearly. Source: Carbon Brief analysis of data from NESO and DESNZ.
While detailed data on underlying electricity demand is not available, it is clear that the shift to EVs and heat pumps is playing an important role in the recent uptick.

There are now <a href='https://www.zap-map.com/ev-stats/ev-m[...]

arket'>around 1.8m EVs on the UK’s roads and another 1m plug-in hybrids. Of this total, some 0.6m new EVs and plug-in hybrids were bought in 2025 alone. In addition, around 100,000 heat pumps are being installed each year. Sales of both technologies are rising fast. Estimates from the NESO “future energy scenarios” point to an additional 2.0TWh of demand from new EVs in 2025, compared with 2024. They also suggest that newly installed heat pumps added around 0.2TWh of additional demand, while data centres added 0.4TWh.

By 2030, NESO’s scenarios suggest that electricity use for these three sources alone will rise by around 30TWh, equivalent to around 10% of total demand in 2025.

EVs would have the biggest impact, adding 17TWh to demand by 2030, NESO says, with heat pumps adding another 3TWh. Data-centre growth is highly uncertain, but could add 12TWh. Gas growth

At the same time as UK electricity demand was growing by 4TWh in 2025, the country also lost a total of 10TWh of supply as a result of a series of small changes.

First, 2025 was the UK’s first full year without coal power since 1881, resulting in the loss of 2TWh of generation. Second, the UK’s nuclear fleet saw output falling to the lowest level in half a century, after a series of refuelling breaks and outages, which cut generation by 5TWh.

Third, after a big jump in imports in 2024, the UK saw a small decline in 2025, as well as a more notable increase in the amount of electricity exported to other countries. This pushed the country’s net imports down by 1TWh (4%).

The scale of cross-border trade in electricity is expected to increase as the UK has significantly expanded the number of interconnections with other markets.

However, the government’s clean-power targets for 2030 imply that the UK would become a net exporter, sending more electricity overseas than it receives from other countries. At present, it remains a significant net importer, with these contributions accounting for 109% of supplies.

Finally, other sources of generation – including oil – also declined in 2025, reducing UK supplies by another 2TWh, as shown in the figure below.
https://www.carbonbrief.org/wp-content/uploads/2025/12/Gas_generation_increased_in_2025_despite_renewables_growth-scaled.png Change in electricity supply by source between 2024 and 2025, TWh. Source: Carbon Brief analysis of data from NESO and DESNZ.
These losses in UK electricity supply were met by the already-mentioned increases in generation from gas, solar, wind and biomass, as shown in the figure above.

The government’s targets for decarbonising the UK’s electricity supplies will face similar challenges in the years to come as electrification – and, potentially, data centres – continue to push up demand.

All but one of the UK’s existing nuclear power plants are set to retire by 2030, meaning the loss of another 27TWh of nuclear generation.

This will be replaced by new nuclear capacity, but only slowly. The 3.2GW Hinkley Point C plant in S[...]

omerset is set to start operating in 2030 at the earliest and its sister plant, Sizewell C in Suffolk, not until at least another five years later.

Despite backing from ministers for small modular reactors, the timeline for any buildout is uncertain, with the latest government release referring to the “mid-2030s”.

Meanwhile, biomass generation is likely to decline as the output of Drax is scaled back from 2027.

Stalling progress

Taken together, the various changes in the UK’s electricity supplies in 2025 mean that efforts to decarbonise the grid stalled, with a small increase in emissions per unit of generation.

The 2% increase in carbon intensity to 126gCO2/kWh is illustrated in the figure below and comes after electricity was the “cleanest ever” in 2024, at 124gCO2/kWh.
https://www.carbonbrief.org/wp-content/uploads/2025/12/Progress_on_grid_decarbonisation_stalled_in_20252C_with_a_small_uptick_in_emissions_per_unit_of_electricity_1.png Carbon intensity of UK electricity supplies, gCO2/kWh. Source: Carbon Brief analysis of data from NESO and DESNZ.
The stalling progress on cleaning up the UK’s grid reflects the balance of record renewables, rising demand and rising gas generation, along with poor output from nuclear power.

Nevertheless, a series of other new records were set during 2025.

NESO ran the transmission grid on the island of Great Britain (GB; namely, England, Wales and Scotland) with a record 97.7% “zero-carbon operation” (ZCO) on 1 April 2025.

Note that this measure excludes gas plants that also generate heat – known as combined heat and power, or CHP – as well as waste incinerators and all other generators that do not connect to the transmission network, which means that it does not include most solar or onshore wind.

NESO was unable to meet its target – first set in 2019 – for 100% ZCO during 2025, meaning it did not succeed in running the transmission grid without any fossil fuels for half an hour.

Other records set in 2025 include:

* GB ran on 100% clean power, after accounting for exports, for a record 87 hours in 2025, up from 64.5 hours in 2024.
* Total GB renewable generation from wind, solar, biomass and hydro reached a record 31.3GW from 13:30-14:00 on 4 July 2025, meeting 84% of demand.
* GB wind generation reached a record 23.8GW for half an hour on 5 December 2025, when it met 52% of GB demand.
* GB solar reached a record 14.0GW at 13:00 on 8 July 2025, when it met 40% of demand.

The government has separate targets for at least 95% of electricity generation and 100% of demand on the island of Great Britain to come from low-carbon sources by 2030.

These goals, similar to the NESO target, exclude Northern Ireland, CHP and waste incinerators. However, they include distributed renewables, such as solar and onshore wind.

These definitions mean it is hard to measure progress independently. The most recent government figures show that 74% of qualifying generation in GB was from low-carbon sources in 2024.

Carbon Brief’s figures for the whole UK show that low-carbon sources made up a record 58% of electricity[...]