Billed as the “Amazon COP”, the UN climate talks will see the debut of Brazil’s flagship fund to “reward” tropical countries for keeping their forests intact.
The Tropical Forest Forever Facility (TFFF) will be launched at the COP30 leaders’ summit on 6 November.
The fund aims to raise and invest $125bn from a range of sources, with excess returns channelled to up to 74 developing countries that sufficiently protect their forests.
This, according to Brazil, would make it one of the biggest multilateral investment funds for nature.
(For comparison, the Green Climate Fund’s portfolio is around $18bn.)
While Brazil expects TFFF to “transform the world’s approach to environmental conservation”, many critics remain unconvinced.
They argue that conservation funding for climate-critical forests should not depend on “betting on stock market prices” and instead call for new biodiversity finance.
Here, Carbon Brief takes a closer look at where the fund came from, how it will be set up and how it is supposed to work.
What is the Tropical Forest Forever Facility?
First officially proposed by Brazil at COP28 in Dubai in 2023, the Tropical Forest Forever Facility aims to pay up to 74 developing tropical forest countries for keeping their existing old-growth forests intact.
It plans to do this by raising $25bn in capital from wealthy “sponsor” governments and philanthropies, which – it hopes – will attract an additional $100bn in private investment.
Returns on these investments will go towards paying back investors and making “forest payments” to countries that increase or maintain their forest cover.
On 4 November, Brazil’s finance minister Fernando Haddad told Bloomberg that “he believed the fund could raise $10bn by next year”, less than half the original target.
While the facility’s official launch is slated for COP30, its rules are still being finalised after several iterations of “concept notes” and consultations.
However, the idea that underpins the fund is not new.
Former World Bank treasurer Kenneth Lay first floated the idea of a Tropical Forest Finance Facility around 15 years ago.
Lay and others later envisioned the TFFF as a “pay-for-performance” sovereign wealth fund for forests. In their design of the TFFF, loans from developed countries and private investors would have been invested in the debt markets of tropical forest countries, with excess returns being allocated annually as “rainforest rewards”.
In their thinking, TFFF offered a “highly-visible, large-scale reward for successfully tackling deforestation without increasing funding demands” on developed countries, according to a 2018 article for the Center for Global Development.
Others central to the TFFF’s current design are Christopher Egerton-Warburton – founder of London-based Lion’s Head Global Partners, who is credited with engineering the facility’s financial structure – and Garo Batmanian, director of Brazil’s forestry service.
What is it designed to achieve?
The ultimate goal of the TFFF is to pay for the conservation of the world’s major rainforests, which provide a range of ecosystem services, including carbon storage.
In a statement from the COP30 presidency, André Aquino, special advisor on economy and environment at Brazil’s ministry of environment, said:
“What the TFFF seeks is for the world to remunerate part of these services. It is to remunerate forests as the basis of life, as the basis of the economy, for our well-being.”
On the ground, this mechanism could help landowners to conserve trees and forests by ensuring that the value they bring as standing forests is higher than from cutting them down.
The facility also intends to finance long-term objectives for forest conservation, including policies and programmes for sustainable use and restoration.
More than 70 developing countries that are home to more than 1bn hectares of tropical and sub-tropical forests could be potential recipients from this facility. These countries span the Amazon, Congo and Mekong basins, as well as many other regions.
The following map shows the countries that host tropical rainforests and are potentially eligible to receive funds from the TFFF.
To be selected as beneficiaries, countries will require transparent financial management systems and must commit to allocating 20% of the funds to Indigenous peoples and traditional communities, according to the draft rules.
These countries would need to have a deforestation rate – averaged over the previous three years – of no more than 0.5% of their total forested area, with standing forest areas having a canopy cover of at least 20-30% in each hectare to be eligible for payments.
The TFFF’s third concept note says that areas that transition from above to below this 20-30% threshold would be “considered deforested”.
In a recent Yale Environment 360 article, forest ecologists warned that the low level of this threshold – for what counts as a forested area – is “not scientifically credible” and “would allow payments even where industrial logging is occurring in primary forests”.
However, TFFF argues that “including forest areas with lower canopy cover does provide an incentive for maintaining these areas”.
Additionally, payments would be reduced for each hectare of forest loss and for each hectare degraded by fire.
The funds for Indigenous peoples would be “put aside in a different account, following different rules”, Aquino said during a press briefing attended by Carbon Brief.
Brazil’s ministry of environment and climate change invited five countries with rainforests to support the creation of the fund: Colombia, the Democratic Republic of Congo, Ghana, Indonesia and Malaysia.
Individual national governments that are beneficiaries of the scheme would be free to define how and where the generated funds would be distributed.
How will the fund work?
The TFFF is split into two entities, with a secretariat to coordinate between them.
The facility is the first of these. It is tasked with setting up the rewards system, eligibility criteria, monitoring methodologies and disbursement rules, as well as engaging with participating recipient countries.
The other is the TFFF’s main financial arm, the Tropical Forest Investment Fund (TFIF) – responsible for raising and managing the TFFF’s resources.
So far, five potential sponsor countries have shown interest in supporting the fund: France, Germany, Norway, the United Arab Emirates and the UK.
These countries, along with five potential recipient countries – Brazil, Colombia, the DRC, Ghana, Indonesia and Malaysia – formed an interim steering committee to shape TFFF’s development.
According to its third concept note, published in October, the TFIF would be a “blended finance vehicle”, pooling public, philanthropic and private funding.
The TFIF is split into two tranches. The first is a “sponsor” tranche, where donor countries and philanthropies are invited to contribute long-term, low-cost capital investment to the tune of $25bn, either from long-term loans, guarantees or outright grants.
So far, Brazil’s initial pledge of $1bn to the facility is the only such pledge. Other governments, such as the UK, have played an “active part” in establishing the TFFF.
(Five days before COP30 kicked off, Bloomberg reported that the UK would not be investing in the TFFF, after the government’s treasury department warned that the investment is “not something the UK can afford at a time when it’s trying to tackle its surging debt burden”.)
This $25bn from sponsor countries, in turn, would be expected to absorb risk, cover losses and serve as a catalyst to raise $100bn from institutional investors in the global bond market.
(This sum raised from private investors is described as the “senior market debt” tranche of investment: if the markets see a downturn, private investors are protected first, making their interests “senior” to donor and recipient countries.)
TFIF and its asset managers then invest this $125bn of capital into a mixed portfolio of investments, including public and corporate market bonds, but excluding those with a significant environmental impact. (In a joint letter, issued in October, advocacy and research groups called for a more detailed exclusion criteria.)
Income from these investments, in turn, will be used to pay investors first, then interest to donor countries and, finally, to pay participating forest countries. The payments to participating countries will be roughly $4 per hectare of standing forest (subject to annual adjustment for inflation), as verified by satellite imagery.
The World Bank confirmed in September 2025 that it will serve as a trustee to the facility and host its interim secretariat.
Liane Schalatek, a climate finance expert and associate director of German policy thinktank Heinrich-Böll-Stiftung’s Washington office, tells Carbon Brief:
“It’s a very clear hierarchy: you serve the money raised on the market and capital investors first before you go to the intended purpose of the fund – and that is compensating countries for basically leaving their tropical forest standing. To me, it seems that the focus is on the money, not necessarily on the outcome. That is really worrisome.”
While sponsor countries are guaranteed their money back over a 40-year period, payouts to forest countries depend on investment returns. These are subject to market risks and volatility and, therefore, are not guaranteed.
According to Frederic Hache, co-founder of the EU Green Finance Observatory thinktank, payouts promised by the TFFF are “really not appropriate to the emergency of the [biodiversity and climate] crises” and do not address their “root drivers”. Hache tells Carbon Brief:
“Even if you meet the very hard criteria as a country to get this money, obtaining this conservation funding is conditional upon financial market conditions and the skill of an asset manager. That’s not very generous and that’s not very appropriate.”
Hache warns that if the fund does not make enough money or experiences losses, the “first thing that is impacted is the forest payment”, which could be put on hold, while “sponsor capital protects private investors with taxpayer money”.
What issues might the fund face?
Civil-society organisations and climate finance experts have warned of several risks and gaps within the facility.
Finance fragmentation
Experts who spoke to Carbon Brief expressed concerns that TFFF could erode the legitimacy of existing, but under-resourced, multilateral funds for climate and biodiversity, as well as dilute the legal obligations of developed countries to pay their “fair share” of nature finance.
While the TFFF hopes to contribute to the goals of all three UN conventions – climate, biodiversity and land degradation – the fund is not officially part of any of the three treaties.
To Schalatek, the fact that the “biggest thing that is going to come out of COP30” is “outside” the UN Framework Convention on Climate Change (UNFCCC) and depends to a large extent on private investment is cause for disappointment.
A keenly awaited report ahead of COP30 is a roadmap towards a wider climate finance target of $1.3tn a year, which could include various sources beyond the jurisdiction of the UN climate process.
Schalatek tells Carbon Brief:
“While we’re trying to have a discussion about protecting the provision of public finance from developed to developing countries [after Baku and amid aid cuts], TFFF is almost contributing to a further undermining of the financial mechanism of the UNFCCC and the Paris Agreement.”
Sarah Colenbrander, director of the climate and sustainability programme at the UK-based global development thinktank ODI, tells Carbon Brief:
“The creation of the Tropical Forest Forever Facility risks not increasing total resources for climate and biodiversity finance, but rather fragmenting the funds already available.”
Potential financial risk
Given the fund’s long-term horizon, a significant challenge is managing financial risk down the line.
This could take the form of a debt crisis in emerging markets, which could “wipe out” sponsor capital and “halt rainforest flows, possibly before they even begin”, economists Max Alexander Matthey and Prof Aidan Hollis wrote in a Substack post in September.
Higher return rates for investors – as mentioned in the third draft of TFFF’s concept note – in combination with high financial fees and operational costs, have left several experts questioning what remains in the way of “rewards” to rainforest countries.
Hache tells Carbon Brief that the TFFF might be “fantastic” for investors who get a “AAA-rated investment without sacrificing any returns”, but real risk is borne by tropical forest countries.
In addition, the mooted payments of $4 a hectare is “ridiculous and not enough to displace alternatives” such as growing cash crops for export, he says, adding:
“$125bn sounds much better than, ‘Oh, we put $2.5bn on the table conditionally’. While there is very little political appetite for giving grant money, this is one of these mechanisms where innovation can obfuscate the lack of ambition and generosity by global-north countries.”
Commodification and transparency
Other experts fear that the new facility could contribute to the commodification of forests and a possible lack of adequate accountability.
The Global Forest Coalition (GFC), an alliance of not-for-profit organisations and Indigenous groups working on forest issues worldwide, have urged countries, Indigenous peoples and civil society to reject the TFFF.
In a press release in October, the GFC said that the TFFF views forests as “financial assets” and warned that the fund is “subject to investment returns, liquidation risks and payouts that are not even guaranteed”.
The press release quotes Mary Louise Malig, policy director at the GFC, who said:
“This is not about conserving forests; it is about conserving the power of elites over forests. It is the continuation of a free market model dressed up as climate finance.”
Information on transparency and governance of the TFFF is unavailable at the moment, says Tyala Ifwanga, forest governance campaigner at Fern, a civil-society organisation that works to protect forest people’s rights in the EU. She tells Carbon Brief that this makes it difficult to assess whether the facility can ensure payments meet the fund’s objectives, adding:
“Corruption is not the only issue we should have in mind here. Some tropical forest countries have autocratic regimes and very limited civic space.”
Pablo Solón, executive director of the Solón Foundation, is also quoted in the GFC press release. He warned:
“The TFFF is a distraction that diverts attention and resources from real solutions like regulation, corporate accountability and direct financing for Indigenous and local initiatives.”
Low Indigenous involvement
Another concern highlighted by the GFC is that while Indigenous peoples and local communities are expected to have “consultative roles”, the “decision-making power rests with governments and financial institutions”.
According to Fern’s Ifwanga, the Global Alliance for Territorial Community – a political platform bringing together coalitions of Indigenous peoples and local communities for defending nature – was involved in developing the TFFF concept notes related to Indigenous peoples and local communities.
She says that although the alliance agrees with the facility, “they are very aware that a lot of work remains to be done to ensure that their voices are heard at every level of the mechanism”.
She also encourages countries to increase direct access to funds for Indigenous communities.
Schalatek says that it is “sinister” that forest communities are being asked to “provide continued stewardship” and preserve forests “without any predictability on how much they’re going to receive for it”, while fund managers can get their money back. She concludes:
“This [TFFF] is exactly the kind of vehicle that gives developed countries the sick leave to not contribute to the GCF [Green Climate Fund], not contribute to the Adaptation Fund…We all know the world has changed, but that doesn’t apply to legal obligations you have signed on to.
“One could probably argue that the Brazilians put a lot more effort into the TFFF than in, for example, thinking about how to deal with the finance agenda within COP30.”
The post COP30: Could Brazil’s ‘Tropical Forest Forever’ fund help tackle climate change? appeared first on Carbon Brief.
COP30: Could Brazil’s ‘Tropical Forest Forever’ fund help tackle climate change?
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.
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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.
This is an online version of Carbon Brief’s weekly DeBriefed email newsletter. Subscribe for free here.
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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