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.
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 for 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 and 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.
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.
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. This 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.
The post Guest post: How to steer EVs towards the road of ‘mass adoption’ appeared first on Carbon Brief.
Guest post: How to steer EVs towards the road of ‘mass adoption’
China and India have declined to back any of their old United Nations carbon credit projects seeking to sell offsets under the new UN market, driving a cull of nearly three-quarters of applicants, analysis of official data shows.
Only 415 out of more than 1,500 projects and programmes hoping to move from the Clean Development Mechanism (CDM) to the new carbon market set up under Article 6.4 of the Paris Agreement won the approval of their host governments by the 30 June deadline – a crucial step in transitioning them.
The two Asian giants, home to two-thirds of all applicants, account for the bulk of the exclusions. Brazil, the other heavyweight of the CDM era, took the opposite path, approving nearly all of its projects in a last-minute rush that leaves it with the largest number of activities still in the running to sell credits under the new mechanism.
Carbon market watchers have long regarded the CDM, set up under the Kyoto Protocol which has now been largely replaced by the Paris Agreement, as largely discredited for failing to drive real emission cuts. They also warned that letting its projects live on could dent confidence in the mechanism’s successor.
-
EU carbon credits could supercharge world’s clean cooking push, France says
The country’s top climate envoy says he discussed using cookstove carbon credits with TotalEnergies, which is working to expand the use of LPG cooking in Africa
If all projects seeking transition had been successful, they could have flooded the market with up to more than 900 million credits generated with largely outdated rules, according to UN estimates. One credit is equivalent to one tonne of carbon dioxide (CO2) and 900 million tonnes is similar to Japan’s annual emissions.
‘New era’
Injy Johnstone, senior research fellow at the Munich-based Max Planck Institute, said the failure of most projects to clear the hurdle sent a significant signal that carbon trading had entered a new era. “The system is trying to remove some of the hot air that had inflated it in the past,” she told Climate Home News.
“The lack of transition is the biggest contribution that Article 6 has made to climate yet,” she added, arguing that leaving “zombie credits” in the market creates confusion, especially for buyers that might not realise these units have lost their value.
Among the schemes that failed to win government approval are nine programmes promoted by fossil fuel companies over a decade ago to subsidise the construction of gas plants in the Global South, which Climate Home News has previously reported on.
Fossil fuel firms seek UN carbon market cash for old gas plants
But one of them, supporting the Ressano Garcia gas plant in Mozambique, could still profit from the new market after the country’s government granted its approval on deadline day itself.
Brazil leads projects transition
Established in 1997 under the Kyoto Protocol, the CDM allowed rich countries to meet part of their climate obligations by financing emission-cutting projects in poorer ones. It drew widespread criticism over its patchy human rights record and for failing to deliver promised climate benefits. Backers of the Article 6.4 market say it is a higher-integrity successor.
CDM projects were given a route back into the new mechanism under certain conditions at COP26 in Glasgow in November 2021, when governments agreed the rules for the Paris Agreement market.
Project developers had until the end of 2023 to apply and host governments were originally given until the end of 2025 to grant approval. But, after requests from many developing countries for an extension, at COP30 in Belém countries agreed to push the deadline back six months to the end of June.
Brazil was the single largest beneficiary of the decision, with all of its 92 approvals coming during the extension window. Hydropower plants, landfill gas schemes and wind farms make up the bulk of the South American country’s surviving portfolio, and hydro is the single most common project type in the global transition pipeline.
Peru greenlit the move of nearly a dozen hydropower plants, Thailand backed a batch of biogas and waste-to-energy schemes, and Mexico squeezed all of its approvals – including a controversial industrial gas project – into the final week. African nations including Zambia, Malawi and Ethiopia backed programmes aiming to switch households to cleaner cooking stoves, which have the potential to generate millions of offsets and are set to be the biggest source of credits among the surviving projects.
Long way from selling credits
Securing government support does not mean a scheme can now automatically sell credits under the Article 6 mechanism. Developers are required to submit additional documentation by the end of 2026 demonstrating that their programmes respect the mechanism’s stricter rules on environmental and social safeguards and on the risk of emission cuts being reversed. The Article 6.4 Supervisory Body, the mechanism’s regulator, has the final say on which projects are allowed into the market.
Those that make it through can sell credits for emission reductions achieved between 2021 and 2025 under the old CDM methodologies, with some adjustments aimed at preventing the creation of excess credits not backed by real emission cuts. For reductions achieved from 2026 onwards, projects will need to switch to new methodologies, which the regulator is currently developing.
So far, 30 programmes have completed the process, and only two cookstove projects in Myanmar have been formally approved to issue credits.
Civil society groups have called for an investigation into the activities in Myanmar over its ties to Myanmar’s military junta – which the UN says is guilty of human rights abuses – and allegations of “massively” overstating its climate impact.
The company behind the scheme said its engagement with authorities “should not be interpreted as political endorsement” of the junta, while disputing the calculations underpinning the claim that too many credits had been issued.
The post Most “zombie credits” locked out of new UN carbon market after China and India snub appeared first on Climate Home News.
Most “zombie credits” locked out of new UN carbon market after China and India snub
Climate Change
Debriefed 17 July 2026: UK ‘firewave’ | Fossil-fuelled heat deaths | London’s Natural History Museum spotlights climate
Welcome to Carbon Brief’s DeBriefed.
An essential guide to the week’s key developments relating to climate change.
This week
Heat and firewaves
‘FIREWAVE’: Wildfires ravaged Europe and North America this week. France utilised water-dumping planes collecting from the Seine to contain a fire in the Fontainebleau forest near Paris, according to the Associated Press. The Financial Times reported that the UK has had “25 non-consecutive days with temperatures of 30C or more, including nine days above 34C”, creating a “firewave” and putting pressure on emergency services. Meanwhile, an “orange haze from Canada wildfires” could be “seen in Ontario and northern US”, said BBC News.
‘NEW NORMAL’: Climate events previously seen as extreme are becoming the “new ‘normal’”, said the Met Office, in a report on the UK’s climate. While last year was the UK’s hottest on record, rising temperatures mean it is expected to be surpassed in the next few years, reported Reuters. Liz Bentley, head of the Royal Meteorological Society, told the Guardian that “climate change has been described by scientists for many years but is now increasingly being felt by the UK population in their own homes and communities”.
Around the world
- ELECTRIFYING PUSH: The European Commission has announced a target for electricity to account for 46% of energy consumption across the bloc by 2040, reported Carbon Pulse. The commission has also made plans to adapt its emissions trading system to “bring relief to industry”, it said.
- FALLING OIL: The International Energy Agency said that global oil demand is expected to decline this year for the first time since 2020, reported the Associated Press.
- US ROLLBACKS: Trump cuts to clean energy support “led to the cancellation or delay of $83bn in investment across hundreds of projects”, reported Reuters. The Trump administration has also changed environmental law to allow development in the habitats of endangered species, according to CNN.
- BURNHAM BEGINS: Incoming UK prime minister Andy Burnham is preparing to announce new North Sea drilling “within days of taking office”, said Bloomberg. Carbon Brief looked at 28 statements that Burnham has made about climate change and fossil fuels.
- DRY JULY: Drought in Uganda led to significant crop losses and at least 16 deaths from starvation, said BBC News.
- ON AI: Australia planned to implement restrictions on energy and water usage for datacentres “amid [an] AI boom”, said the New York Times.
38%
The drop in Brazilian Amazon deforestation in the first half of 2026, compared to last year, reported Al Jazeera.
Latest climate research
- The area of land burned by wildfires in Africa each year has reduced due to a shrinking dry season | Geophysical Research Letters
- Most people do not distinguish between climate adaptation and mitigation when thinking about tackling climate change | Climate Outreach
- An “effort-sharing framework” has been developed to support progress towards the Paris Agreement | npj Climate Action
(For more, see Carbon Brief’s in-depth daily summaries of the top climate news stories on Monday, Tuesday, Wednesday, Thursday and Friday.)
Captured
Carbon Brief explained how more than 1,000 heat-related deaths in England and Wales during May and June were attributed to climate change, accounting for almost half of all heat-related deaths experienced during those months. The article also unpacked the different methods for estimating heat deaths around the world.
Spotlight
Natural History Museum exhibits climate change
This week, Carbon Brief interviews Meaghan Macdonald, senior project and programme manager for London’s Natural History Museum, about their first permanent climate-themed exhibition, Fixing Our Broken Planet.
Carbon Brief: Why are programmes such as Fixing Our Broken Planet so important?
Meaghan Macdonald: One of the main things we’re trying to achieve with Fixing Our Broken Planet is to place the museum as a convener of conversations around the planetary emergency…trying to bring together the different groups of people who need to be involved in this conversation in order to work together to find a solution.
And we find that a lot of the people who come into the gallery weren’t necessarily coming here to see it; they come across it, which is a really great way to engage people who may not have been engaged in that discussion previously.
CB: How does the exhibition engage and inspire visitors?
MM: A driving force for this exhibition is that you are dealing with a subject matter that can be quite disheartening, and one of the things that we were very careful about is to try to make sure that woven throughout the scientific data… is a sense of hope… to enable people to feel empowered to make a difference.
We were able to do things like our “what you can do” labels, which give an example that people can take away with them. We also have “conversation starters”, which is a digital screen that asks people a series of questions related to the planetary emergency. Things like: “Should we mine the deep sea to power the green economy?”…And there’s no right or wrong answer.
We [also] set out very specifically to…forefront the science that’s happening here. We know from multiple studies from thinktanks and organisations that people actually trust our scientists the most.
CB: The museum has set out a goal to “create advocates for the planet”. What does this mean? How does it relate to the exhibition and the museum’s wider climate action?
MM: The aim of the museum is to get to a place where both people and the planet thrive. Being a library of the natural world, it is our duty to be standing up for it and to help people find their way, fighting for nature’s side.
In order to create those advocates, the aim of the [exhibition] and the wider advocacy programmes at the museum is to try to find ways to bring all these people [individuals, policymakers, industry, scientists] together.
We have the wider programme with Fixing Our Broken Planet. We have Generation Hope…a free graphic panel version of our display in the gallery that we have been able to get into a number of venues in Bangalore…the very long-standing and beloved wildlife photographer of the year [exhibition]…our urban nature movement…[and] an initiative that we are doing with the Department for Education called the National Education Nature Park.
Watch, read, listen
STUBBORN HOPE: For the Conversation, climate scientist Prof Peter Stott argued that researchers need to “talk more about the very worst-case scenarios” and the possibility for action.
EXTREME: Vox’s the Gray Area podcast spoke to New York Times journalist David Wallace-Wells about the possibility of a “Godzilla” El Niño.
RESPONSIBILITY: For Climate Home News, two researchers from the Center for International Environmental Law explored how “major emitting countries knew of climate risks decades earlier than claimed”.
Coming up
- 13-31 July: Meeting of the International Seabed Authority assembly and council, Kingston, Jamaica
- 17-19 July: 3rd International Conference on Environment and Sustainable Development, London
- 19 July: Presidential election, São Tomé and Príncipe
Pick of the jobs
- Zero Carbon Analytics, research lead | Salary: Unknown. Location: Remote
- Met Office, ocean climate scientific manager | Salary: £54,515-£58,582. Location: Exeter
- National Trust, land use and nature delivery partner | Salary: £44,499. Location: Newcastle or York
DeBriefed is edited by Daisy Dunne. Please send any tips or feedback to debriefed@carbonbrief.org.
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The post Debriefed 17 July 2026: UK ‘firewave’ | Fossil-fuelled heat deaths | London’s Natural History Museum spotlights climate appeared first on Carbon Brief.
Recent weeks have seen a flurry of reports from public health authorities and scientists that estimate the deaths caused by Europe’s record-breaking summer heatwaves.
In France, the national public health agency reported 2,025 excess deaths over the week where the heatwave peaked in June.
Authorities in Germany and Netherlands put the excess death toll during the same seven-day period at 5,753 and 533, respectively.
An analysis from climate scientists in Carbon Brief found that France saw more than 2,700 heat-related deaths over 17 days in June.
Separate research estimated there had been 2,700 heat-related deaths in the UK’s May and June heatwaves – 42% of which had been caused by human-caused climate change.
There are a number of methods for how academics and governments tally deaths caused by extreme heat, each with their own advantages and drawbacks.
Here, Carbon Brief looks at the different ways scientists and public health authorities have calculated the death toll of Europe’s record-breaking summer heat.
- How established is the science of calculating heat deaths?
- What are the different approaches to counting heat deaths?
- What do the latest figures show for Europe’s May and June heatwaves?
- What are the pros and cons of the ‘excess deaths’ method?
- What are the pros and cons of the ‘statistical modelling’ method?
How established is the science of calculating heat deaths?
Economists and epidemiologists have been studying the relationship between heat and mortality for nearly a century.
A pioneering study published in 1923 by geographer Ellsworth Huntington and economist Margaret Justin that looked at mortality data for New York City over 1882-88 found that deaths increased rapidly as temperatures rose above 17C.
As global temperatures have risen in response to human-caused carbon emissions, scientists have increasingly sought to understand how warming could impact mortality.
The study of mortality caused by specific heatwave events dates back a few decades, with a 1995 heatwave in Chicago among the earliest events to be studied in detail.
Over the past decade, a growing number of studies have gone a step further, by estimating the number of deaths caused by a specific heatwave event and then attributing a percentage or number of those deaths to human-caused climate change.
Carbon Brief covered the first study of this type, which was published in Environmental Research Letters in 2016 and focused on a 2003 summer heatwave that caused tens of thousands of deaths across Europe.
The study estimated that 506 of the 735 summer fatalities in Paris and 64 of the 315 in London were a result of human influence on the climate.
More recently, a study in Climatic Change found that 27% of deaths in a 2018 heatwave in Zurich, Switzerland were linked to human-caused climate change and a paper in Science Advances estimated that 11-15% of deaths in a 2021 heatwave in British Columbia were attributable to global warming.
Dr Christopher Callahan, assistant professor at the O’Neill School of Public and Environmental Affairs at Indiana University, tells Carbon Brief this type of “two-step” study has “really exploded” in recent years:
“It is really only in the last five to 10 years that we have seen this, partly because it does require interdisciplinary expertise. You need people who know how to run the epidemiological models and you need a climate analysis of the counterfactual [world] without climate change, which is its own effort.”
What are the different approaches to counting heat deaths?
A central challenge in estimating deaths from a heatwave is that heat is rarely recorded as the primary cause of death on death certificates.
However, exposure to high temperatures has wide-ranging effects on the human body, including the strain of keeping cool. This effort places pressure on the heart and kidneys.
As a result, heat extremes can worsen health risks from chronic conditions and cause acute kidney injury. Researchers have linked heat to increased mortality from respiratory and cardiovascular diseases, as well as dementia and Alzheimer’s.
As a result, public health authorities and scientists cannot depend on death certificates for a full count of heat-related deaths. They instead estimate heat deaths using a number of different approaches, each with assumptions baked into their calculations.
Dr Garyfallos Konstantinoudis, who researches methods for calculating excess mortality due to extreme events at the Grantham Institute for Climate Change and the Environment at Imperial College, tells Carbon Brief there is “no ground truth” when it comes to tallying heat-related deaths:
“We don’t know what the heat-related deaths are, so we rely on different models to describe the picture.”
This makes the study of deaths from heatwaves similar to those from air pollution, he says:
“This sort of health-impact assessment has been done for years on studies related to deaths from air pollution, which have the same problem. Air pollution, until very recently, was not recorded on death certificates.
“[However], for air pollution, the [scientific] literature is much larger, so no one questions that air pollution is toxic and kills. This sort of messaging for heat is more recent.”
There are, broadly speaking, two approaches to calculating deaths during a heatwave.
The first involves counting the number of excess deaths relative to a period in the past.
This method – often referred to as an “excess deaths” approach – looks at how many people died during a particular time period compared to a baseline period where there was no heatwave.
To do this, public health authorities and researchers rely on official death figures reported by country authorities.
The heat death tolls published in recent weeks by public health agencies in Belgium, France, Germany and the Netherlands relied on this approach.
(For more, see: What are the pros and cons of the ‘excess deaths’ method?)
The second method uses long-term mortality data to understand the statistical relationship between temperature and mortality in a given place. The model that emerges can be used to infer the number of deaths from a heatwave in that place.
In a rapid analysis published this week, researchers at Imperial College London, the London School of Hygiene and Tropical Medicine (LSHTM) and the Met Office used this approach to estimate that the May and June heatwaves in the UK caused the deaths of 2,700 people.
Dr Callahan – working with Prof Andrew Dessler, director of the Texas Center for Extreme Weather at Texas A&M University – used this method to estimate that more than 2,700 people had died in France over a 17-day period in June in an analysis for Carbon Brief.
(For more: see: What are the pros and cons of the ‘statistical modelling’ method?)
The majority of the figures released in the wake of Europe’s June heatwave have relied on these two methods.
There is a third way to calculate heat deaths, which is to look at official counts of deaths attributed on death certificates to heatstroke.
Callahan tells Carbon Brief that the “death-certificate coding” appears to have fallen out of favour in Europe – which he says is a “smart move” given that it does not provide a “full accounting”.
Nevertheless, some public health authorities are still using this method. For example, in the wake of the heatwave in the US earlier this month, public health data showed 29 people in New Jersey and three people in New York had died from “heat-related illnesses”.
Scientists tell Carbon Brief the excess deaths and statistical modelling approaches both have advantages and drawbacks. These are explored below.
What do the latest figures show for Europe’s May and June heatwaves?
The table below shows the death numbers that have been reported by governments and researchers for Europe’s May and June heatwaves, including the approach used to reach the figures.
It suggests that multiple countries in Europe experienced more than 1,000 heat-related deaths during the late June heatwave, with authorities in Germany counting more than 5,000.
Meanwhile, the EuroMoMo mortality monitoring system estimated there were more than 10,500 excess deaths across 27 countries during the June heatwave.
| Reported | Source | Country / region | Dates | Days | Deaths | Link | Approach |
|---|---|---|---|---|---|---|---|
| 28/06/2026 | Public Health France | France | 22-27 June | 6 | 1,000 | santepubliquefrance.fr | Excess deaths |
| 29/06/2026 | World Health Organization | Europe | 21-28 June | 8 | 1,300 | x.com/DrTedros/status | Excess deaths |
| 01/07/2026 | Carlos III Health Institute (MoMo) | Spain | 1-30 June | 30 | 1,033 | dw.com | Excess deaths (all-cause and temperature-attributable) |
| 02/07/2026 | National Institute for Public Health and the Environment | Netherlands | 22-28 June | 7 | 480 | rivm.nl | Excess deaths |
| 03/07/2026 | Public Health France | France | 22-28 June | 7 | 2,025 | santepubliquefrance.fr | Excess deaths |
| 07/07/2026 | Chris Callahan/Andrew Dessler | France | 12-29 June | 18 | 2,766 | carbonbrief.org | Statistical modelling |
| 08/07/2026 | Chris Callahan | Europe | 15-28 June | 14 | 13,975 | zenodo.org | Statistical modelling |
| 08/07/2026 | Sciensano | Belgium | 18 June – 1 July | 14 | 1,747 | brusselstimes.com | Excess deaths |
| 09/07/2026 | Robert Koch Institute | Germany | 22-28 June | 7 | 5,120 | rki.de | Statistical modelling |
| 13/07/2026 | Met Office/LSHTM/Imperial | England and Wales | 22-27 June | 6 | 2,183 | drive.google.com | Statistical modelling |
| 13/07/2026 | Met Office/LSHTM/Imperial | England and Wales | 24-26 May | 3 | 553 | drive.google.com | Statistical modelling |
| 13/07/2026 | EURO Mo/Mo | 27 European countries | 22-28 June | 7 | 10,650 | reuters.com | Excess deaths |
| 07/07/2025 | National Institute for Public Health and the Environment | Netherlands | 22-28 June | 7 | 577 | archive.ph | Excess deaths |
| 14/07/2026 | Germany Federal Statistical Office (Destatis) | Germany | 22-28 June | 7 | 5,753 | destatis.de | Excess deaths |
In most instances, Carbon Brief has linked to the figures published by public health authorities, where numbers were first reported. In some instances, figures were released on dashboards or webpages that are updated weekly. In these cases, Carbon Brief has linked to media reports or archived web content.
What are the pros and cons of the ‘excess deaths’ method?
The excess deaths approach looks at how many more people died during a particular time period compared to a baseline period of the same length.
For instance, on 14 July, Germany’s federal statistics agency, Destatis, published figures showing Germany saw 32% more deaths than the average in the week of 22-28 June, which was dominated by the heatwave.
Specifically, the agency said that 23,932 deaths had been recorded that week, compared to an average of 18,179 in that calendar week across the years 2022-25.
This suggests there were 5,753 excess deaths during the heatwave week. (This was a slight increase from preliminary Destatis figures released a week earlier, covered by Bloomberg.)
The Netherlands similarly calculates excess deaths by comparing death figures against an average of deaths in a similar period during unspecified “previous years”.
Data published by the country’s National Institute for Public Health and the Environment (RIVM) shows that, during the week of 22-28 June, an estimated 3,626 people died in total in the northern European country.
This is 577 more deaths than the 3,049 expected at that time of year, it said. (This is a slight revision upwards from the 480 excess deaths reported on 4 July by NL Times based on preliminary figures from NVIM.)
Callahan says that the excess deaths approach has the benefit of being rapid and relatively uncomplicated:
“It is something that public health authorities can put out fairly quickly without having to run a fancy model and do coding like the academic scientists do. It is a short-term, high-impact, rapid estimate of mortality.”
The drawback to the approach is that it is impossible to decipher what percentage of these “all-mortality” excess deaths are, in fact, heat-related.
Imperial College’s Konstantinoudis notes that the public often “feels more comfortable” with the excess deaths approach over the statistical modelling approach because the data it is using – the official death numbers – is based on real-world data.
However, he stresses that excess deaths figures are based on a series of assumptions, including the reference period picked by researchers and how the numbers are interpreted.
Statisticians and researchers have to make a series of decisions, including what period to use as a comparative baseline. For example, the baseline period could be the week before a heatwave, the same week a year before – or an average of the same week across multiple years in the past. If averaging mortality of a similar period across a number of previous years, they must decide how much “weight”, or influence, each year should have.
They must also decide how to account for spikes in deaths during the Covid-19 pandemic years, as well as the gradual rise in average temperatures due to global warming.
During the pandemic, many governments and the World Health Organization (WHO) used the excess deaths approach to count deaths. The WHO said this metric was more “comparable” and “objective” than relying on national reports of Covid-19 deaths, given that different countries used different criteria for this classification.
A notable example of how assumptions can skew excess death figures came during this period, when the WHO estimated in 2022 that Germany had seen 195,000 excess deaths over two years of pandemic.
However, after statisticians and epidemiologists pointed out the assumptions in the model were not suited to Germany’s demographics, the WHO retracted the figure and eventually reduced it to 122,000 and then later to 102,000.
Konstantinoudis explains:
“Covid taught us that it is complicated. Depending on the different assumptions used in the excess-mortality approach, you get different results…There is a scientific basis, but we should acknowledge the assumptions.”
What are the pros and cons of the ‘statistical modelling’ method?
In the statistical modelling approach, researchers use models to determine the specific relationship between mortality and temperature for a particular location and then apply it to temperatures observed during a heatwave.
This allows them to estimate the overall number of deaths that were caused by a heatwave.
Previous research has revealed that, in most places of the world, there is a U-shaped response of mortality to temperature – where deaths increase rapidly in cold or hot conditions as daily maximum temperatures depart further from an “optimum temperature”.
For example, research published in Proceedings of the National Academy of Sciences in 2025 found that mortality rates in France rise as daily maximum temperatures move away from approximately 20C. This is shown in the chart below.
Indiana University’s Callahan say this approach allows scientists to “formally establish a relationship between the temperature and the mortality”, adding:
“If you do these calculations right, you can credibly say your entire estimate of mortality is heat-related.”
Prof Antonio Gasparrini, biostatistician and epidemiologist at LSHTM, explains the method relies on “timeseries models that apply relatively sophisticated statistical methods in which you ‘smooth’ trends occurring in time, so you control for long-term trends and seasonality”.
He says that these models also allow researchers to “remove” trends affecting mortality that are unrelated to heat – for instance, the impacts of the pandemic. They can also “add” other information, such as around how air pollution combines with heat to threaten vulnerable populations.
Gasparrini adds:
“What statistical modelling can bring is that it is more refined. It can link specific temperatures to specific impacts rather than just looking at the event [in the whole]. And also, it can be localised – [data] can be stratified at a fine scale and we can look at impacts at different scales.
“So, it is more informative. But, at the same time, of course, it’s based on more assumptions than the [excess deaths approach] and, of course, needs to be checked and compared.”
The approach depends on a number of judgment calls from scientists and statisticians, including the years picked to underpin the model and how to capture the lag in deaths in the days and weeks after a heatwave event.
They must also decide at what threshold to start counting deaths – in other words, whether to count all deaths above the “optimum temperature” or set a higher, more extreme value – and whether and how to account for any adaptation to heat extremes that may have been put in place in the study area.
A benefit of the statistical modelling approach is that it opens the door for being able to attribute a specific number of deaths to human-caused climate change.
By applying the temperature-mortality curve to both the temperatures of the recent heatwave and a counterfactual world without climate change, scientists can estimate what proportion of estimated deaths only occurred because the world is warming.
For instance, Imperial College, LSHTM and Met Office researchers found that 59% and 38% of heat-related deaths in the UK’s May and June heatwaves, respectively, could be attributed to climate change. Their findings are shown in the chart below.
Some climate-sceptic commentators have argued that modelled estimates are hypotheses and should therefore be treated with caution.
On 13 July, climate-sceptic news website GB News covered a blog post by Oxford academics that argued the figure that 2,700 people had died in the UK’s May and June heatwaves was not reflected in the provisional “all-mortality” data put out by the UK’s Office for National Statistics (ONS). Quoting the blog, GB News said:
“Modelling tells us nothing. Models explore possibilities; surveillance tells us what happened. When the two disagree, our instinct should be to investigate the data rather than simply trust the model.”
However, Imperial’s Konstantinoudis – who worked on the models behind the 2,700 figure – says it is important to await the UK Health and Security Agency (UKHSA)’s annual heat mortality report before arriving at any conclusions. He explains:
“While we are entirely clear that our current findings are modelled estimates, this methodology has consistently delivered comparable results to the UKHSA’s own official analyses of observed deaths for past heat events.”
(The UKHSA report will include updated figures and estimate excess deaths from heat based on specific periods of heat in different regions, whereas the provisional ONS figures cover all national deaths during a full-week period.)
Konstantinoudis says both the excess deaths and statistical modelling approaches have been the subject of extensive peer-reviewed scientific study and can provide a “holistic view of what is happening” when used together.
Studies that have compared statistical modelling approaches for estimating heatwave deaths with excess death figures in the UK have found they yield broadly similar results.
The post Q&A: Europe’s May and June heatwave deaths – and how they were counted appeared first on Carbon Brief.
Q&A: Europe’s May and June heatwave deaths – and how they were counted
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