“Extreme” wildfires emitted more than 8bn tonnes of carbon dioxide during the 2024-25 “global fire season”, according to a new report.
The annual “state of wildfires” report from an international team of scientists finds that fires burned at least 3.7m square kilometres of land – an area larger than India – between March 2024 and February 2025.
This is almost 10% below the average annual area burned over the past two decades.
But, due to an increase in wildfires in carbon-rich forests, the CO2 emissions resulting from these fires were almost 10% above average.
The report also zooms in on four of the most prominent extreme wildfire events during this time: southern California; north-east Amazonia; South America’s Pantanal-Chiquitano region; and the Congo Basin.
All of these events were found to have been more likely to occur as a result of human-caused climate change.
The researchers identify that, in some cases, the area burned by these fires was 25-35 times larger than it would have been without global warming.
The report also estimates that more than 100 million people around the world were exposed to wildfires in 2024 and 2025.
These fires are “reshaping lives, economies and ecosystems on a global scale”, one of the report authors, Dr Carmen Steinmann from ETH Zürich, said in a statement.
‘Increasing extent and severity’
Scientists from dozens of institutions analyse “extreme wildfires” globally between March 2024 and February 2025 in the second annual edition of the report.
The report explains that the “March-February definition of the global fire season latest global fire season is chosen so as to align with an annual lull in the global fire calendar in the boreal spring months”.
According to the report, the authors “harness and adopt new methodologies brought forward by the scientific community”. They add that in future reports, they hope to “enhance the tools presented in this report to predict extremes with increasing lead times, monitor emerging situations in near-real time and explain their causes rapidly”.
In the report’s “summary for policymakers”, study author Dr Matthew Jones, from the University of East Anglia, says:
“[The report] focuses on the global extreme wildfire events of the global fire season, explains why they happened and fingerprints the role of climate change as one of the key drivers of changing wildfire risk globally.”
The authors aim to “deliver actionable information” to policy experts and wider society about wildfires, the report says.
Using satellite data, the authors find that 3.7m square kilometres (km2) of land burned globally between March 2024 and February 2025. This means that the 2024-25 fire season ranks 16th out of all fire seasons since 2002, indicating below-average burned area compared to the rest of the 21st century.
However, the global fire emissions database shows that the 2024-25 wildfire season drove more than 8bn tonnes of CO2 emissions, according to the report. This is 10% above the average of wildfire seasons since 2002.
Jones explains that this is indicative of a trend towards “increasing extent and severity of fire in global forests, which are carbon-rich”, as opposed to less carbon-rich grassland biomes.
The chart below shows global burned area (top) and carbon emissions (bottom) during the 2024-25 wildfire season, compared to the average over 2002-24, for different world regions. Red bars indicate that the 2024-25 wildfire season had higher-than-average burned area or emissions for the given region, while blue indicates lower-than-average numbers.
Savannas, grasslands and shrublands account for more than 80% of the burned area in a typical year, with forests and croplands making up the rest.
According to the report, burned area in tropical and subtropical grasslands, savannah and shrublands was 10% below the 2002-24 average over 2024-25, but still contributed 70% towards the total global burned area.
The 2024-25 wildfire season was the second consecutive year that African savannahs “experienced a low fire season”, the report notes, with below average burned area and carbon emissions.
Meanwhile, the report finds that the greatest increases in burned area and carbon emissions during the 2024-25 wildfire season were seen in the Canada’s boreal forests, the moist tropical forests in the Amazon region, the Chiquitano dry forests of Bolivia and the Cerrado – a tropical savannah in central Brazil.
The graphic below shows some key figures from the 2024-25 wildfire season.
Study author Dr Douglas Kelley, from the UK Centre for Ecology and Hydrology, told a press briefing that the author team spent time “actively engaging with a big regional panel of experts”.
The team identified four “focal events” – extreme wildfire events that were chosen both for the severity of the fire and the impacts on people and the environment.
For each focal point, the study authors assessed the drivers of the wildfire. They also used attribution – a field of climate science that aims to identify the “fingerprint” of climate change on an extreme event – to determine the contribution of human-caused climate change.
Finally, the authors estimated the likelihood of similar events occurring in the future as the climate continues to warm over the coming century.
Kelley told the press briefing that “capturing fires themselves can be quite tricky”, because they are affected by a range of different factors.
The report notes that wildfires are affected by changes in weather, with hot and dry weather providing the best conditions for wildfires. It adds that changes in land use are also important, as they can affect ignition.
Kelley explained that the report authors used “multiple types of attribution” to capture these different factors, using a range of fire models, weather forecasting models and land use data.
North America
In North America, 2024-25 was an “extreme” fire year, the report says.
Both burned area and carbon emissions reached their second-highest levels since records began in 2002 and 2003, respectively. Across the continent, the burned area was 35% higher than the average since 2002 and the carbon emissions were more than double the average emissions since 2003.
In Canada, 46,000km2 of land burned during the 2024-25 fire season, releasing 282m tonnes of carbon (Mt). The burned area was 85% higher than average, but the associated emissions were more than 200% higher than average, according to the report.
The report also notes that the wildfire season started early in Canada in 2024, due to earlier-than-normal snowmelt, as well as persistent, multiyear drought and “holdover fires” that reignited in the spring after smouldering through the winter months.
In the US, more than 64,000 individual wildfires contributed to a total burned area larger than 36,000km2. More than 8,000 wildfires in Mexico led to a record 16,500km2 of burned area.
The regions experiencing record or near-record burned area and carbon emissions were varied: from the Canadian tundra and the north-western US mountain ranges to California’s grasslands and Mexico’s tropical forests. In the far-northern boreal forest – which contains around 20% of the world’s forest carbon – the season trailed only the record-breaking 2023-24 fire season in burned area and associated emissions.
The researchers select the January 2025 southern California wildfires as one of the four “focal events” of the report.
The maps below show the locations of the four focal events: southern California, the Congo Basin, north-east Amazonia and the Pantanal-Chiquitano. The colours show the percentage difference from the average burned area, with blue indicating less burned area than average and darker browns showing more burned area.
In early January 2025, more than a dozen fires broke out in and around Los Angeles. Although January is “well outside the typical fire period”, the fires “became the most expensive wildfires ever recorded in just a few short days”, Prof Crystal Kolden – a study author and the director of the University of California, Merced’s Fire Resilience Center – wrote in the report.
The two largest fires, named the Palisades fire and the Eaton fire, resulted in at least 30 deaths, more than 11,500 homes destroyed and more than 153,000 people being evacuated from their homes.
The fires resulted in estimated economic losses of $140bn, placing “substantial pressure on the already volatile home insurance market in California”, according to the report. It notes that the fires also contributed to the “housing and affordability crisis” in southern California.
The report says that the severity of the January fires was largely due to intensifying extremes in the water cycle – an unusually wet period that allowed vegetation to flourish, followed by an unusually arid winter that dried out that vegetation, turning it into fuel. It notes:
“Between 5 and 25 January, favourable weather, fuel availability and ignition sources aligned, leading to create ideal conditions for ignition and rapid fire spread.
“The substantial suppression efforts deployed is unaccounted for in our modelling framework and could be one of the possible reasons the fires did not escalate even further.”
Previous attribution analysis found that the January 2025 fires were “likely influenced” by human-driven climate change. The report authors also find that the burned area in the southern California event was 25 times greater due to climate change.
However, whether extreme fire activity in southern California continues to intensify depends largely on how the region’s plants and trees respond to increased atmospheric CO2, the report says. It also notes that climate models disagree as to whether wintertime rainfall will increase or decrease in future climates.
South America
The report finds that South America had a total area burned by wildfires of 120,000km2 during the 2024-25 fire season – 35% higher than average.
That translated into the release of 263Mt of carbon – the “highest carbon emissions on record for the continent” and 84% above average, the report says.
Jones, a study author, said in a press briefing that South America “hasn’t seen carbon emissions like this on record before”.
The report underlines that South America’s fire season was “unprecedented” in many ways, such as fire extent, emission levels, intensity and their impacts on society and the environment, although not in the number of fires.
For example, fires in the north-east Amazon impacted air quality, crops, houses and native vegetation, affecting people living in the region, including Indigenous peoples such as the Yanomami, the report says.
The country with the largest area burned by wildfires during the 2024-25 fire season was Brazil, with a total burned area of 243,000km2, followed by Bolivia, with a total of 107,000km2 of burned area, and Venezuela, with a total of 43,000km2 of burned area.
The most-affected biomes in the region were the Amazon rainforest, with 47,000km2 of wildfires above the average since 2002.
Second was the Chiquitano and Chaco dry forests – encompassing parts of Bolivia, Brazil, Paraguay and Argentina. These biomes experienced a “record-breaking” fire season with more than 46,000km2 of burned area. These fires resulted in 100Mt of carbon emissions – six times higher than the average since 2003.
More than 46,000km2 of the Pantanal – the largest tropical wetland located in Brazil, Bolivia and Paraguay – burned in 2024-25, with associated carbon emissions of 67Mt above the average.
According to the report, fire activity in the region was primarily driven by “anomalous dry weather”.
In the north-eastern Amazon, the severity of the fire season between January and April 2024 was compounded by natural sources of climate variability, such as El Niño and the Atlantic Meridional Mode, which contributed to very high temperatures and absence of rainfall. There, deep soil moisture dropped to 1%.
Meanwhile, in Pantanal and Chiquitano, “extreme dry weather” since 2023 and “multiple years of below-average rainfall” contributed to the severe fires, the report says. Study author Dr Francesca Di Giuseppe said in a briefing that the “wet season that usually happens between February and May failed completely to recharge the soil that kept completely dry and this drove most of the fire season” in the region.
The authors conduct an attribution analysis and find that the fire weather conditions in the north-eastern Amazon that season were “significantly more likely” due to climate change. In the Pantanal and Chiquitano, the conditions were 4.2-5.5 times more likely due to climate change.
Africa
Overall, the scale of fires across Africa was “well-below average” in 2024 and 2025, the report finds, except in certain areas, including the Congo Basin, northern Angola and South Africa.
In 2024, a record-high amount of land was burned in the Congo Basin – a biodiverse region in central Africa spanning six countries that holds the world’s second-largest tropical forest. This burned area was 28% higher than the annual average and there were 4,000 fires in total, 20% more than usual, in 2024.
Fires also caused “hazardous” air pollution and contributed to the Congo Basin’s highest loss of primary forest in a decade.
The analysis in the report finds that it is “virtually certain” that human-caused climate change contributed to the extreme fire weather in this region in July and August 2024.
The hot, dry and windy conditions were 3-8 times more likely to occur as a result of climate change and the area scorched by fires was three times greater than it would have been otherwise, the findings show.
Climate change has also driven an increase of more than 50% in the average annual burned area in the Congo Basin, which the researchers say is “one of the most robust signals of climate influence” in the fire trends they analysed.
Drought was a major factor behind the fires, the report finds, and water stress is expected to be the main driver shaping future fires in the Congo Basin.
These fires are “part of a long-term trend of increasing fire encroachment into African moist forests, driven by climate change and human pressure”, says Prof Michael Wimberly, a professor at the University of Oklahoma who was not involved in the report, but has researched wildfires in Africa. He tells Carbon Brief:
“The increased fire activity in the Congo Basin is troubling because of the vast expanses of unfragmented forests and peatlands that store massive amounts of carbon, provide habitat for threatened species and supply vital resources to local populations.”
The report notes that there is “sparse reporting and poor media coverage” on the impacts of fires in the Congo Basin in 2024, despite millions of people being impacted.
In South Africa, 34 people were killed and thousands of livestock and homes were destroyed in fires last year. In Ivory Coast, 23 people were killed and 50km2 of land was burned.
Dr Glynis Humphrey, a postdoctoral research fellow at the University of Cape Town, who was not involved in the study, adds that a below-average burned area across Africa “does not necessarily indicate a decline in fire risk or impact”. She tells Carbon Brief:
“In some ecosystems, fewer but more intense fires are being observed, which can still have severe ecological and atmospheric consequences.”
Using climate models, the researchers project that fires to the extent of those in the Congo Basin last year could occur up to 50% more often by 2100, under a medium-emissions pathway.
The region is also projected to see more increases in extreme wildfire risk by the end of this century. Gabon, Equatorial Guinea and the central part of the Democratic Republic of the Congo could see some of the largest increases in burned area, which, the report estimates, could double or quadruple in some cases.
Humphrey notes that fire patterns are “shifting” in response to climate change, which is “leading to significant consequences for ecosystems that don’t typically burn – like the forests in the Congo Basin”. She tells Carbon Brief:
“This is of concern, as primary forests harbour critical biodiversity that supports ecosystem functioning and provide services to people…These forests are also sanctuaries for endangered species.”
The post Global wildfires burned an area of land larger than India in 2024 appeared first on Carbon Brief.
Global wildfires burned an area of land larger than India in 2024
Greenhouse Gases
DeBriefed 9 January 2026: US to exit global climate treaty; Venezuelan oil ‘uncertainty’; ‘Hardest truth’ for Africa’s energy transition
Welcome to Carbon Brief’s DeBriefed.
An essential guide to the week’s key developments relating to climate change.
This week
US to pull out from UNFCC, IPCC
CLIMATE RETREAT: The Trump administration announced its intention to withdraw the US from the world’s climate treaty, CNN reported. The move to leave the UN Framework Convention on Climate Change (UNFCCC), in addition to 65 other international organisations, was announced via a White House memorandum that states these bodies “no longer serve American interests”, the outlet added. The New York Times explained that the UNFCCC “counts all of the other nations of the world as members” and described the move as cementing “US isolation from the rest of the world when it comes to fighting climate change”.
MAJOR IMPACT: The Associated Press listed all the organisations that the US is exiting, including other climate-related bodies such as the Intergovernmental Panel on Climate Change (IPCC) and the International Renewable Energy Agency (IRENA). The exit also means the withdrawal of US funding from these bodies, noted the Washington Post. Bloomberg said these climate actions are likely to “significantly limit the global influence of those entities”. Carbon Brief has just published an in-depth Q&A on what Trump’s move means for global climate action.
Oil prices fall after Venezuela operation
UNCERTAIN GLUT: Global oil prices fell slightly this week “after the US operation to seize Venezuelan president Nicolás Maduro created uncertainty over the future of the world’s largest crude reserves”, reported the Financial Times. The South American country produces less than 1% of global oil output, but it holds about 17% of the world’s proven crude reserves, giving it the potential to significantly increase global supply, the publication added.
TRUMP DEMANDS: Meanwhile, Trump said Venezuela “will be turning over” 30-50m barrels of oil to the US, which will be worth around $2.8bn (£2.1bn), reported BBC News. The broadcaster added that Trump claims this oil will be sold at market price and used to “benefit the people of Venezuela and the US”. The announcement “came with few details”, but “marked a significant step up for the US government as it seeks to extend its economic influence in Venezuela and beyond”, said Bloomberg.
Around the world
- MONSOON RAIN: At least 16 people have been killed in flash floods “triggered by torrential rain” in Indonesia, reported the Associated Press.
- BUSHFIRES: Much of Australia is engulfed in an extreme heatwave, said the Guardian. In Victoria, three people are missing amid “out of control” bushfires, reported Reuters.
- TAXING EMISSIONS: The EU’s landmark carbon border levy, known as “CBAM”, came into force on 1 January, despite “fierce opposition” from trading partners and European industry, according to the Financial Times.
- GREEN CONSUMPTION: China’s Ministry of Commerce and eight other government departments released an action plan to accelerate the country’s “green transition of consumption and support high-quality development”, reported Xinhua.
- ACTIVIST ARRESTED: Prominent Indian climate activist Harjeet Singh was arrested following a raid on his home, reported Newslaundry. Federal forces have accused Singh of “misusing foreign funds to influence government policies”, a suggestion that Singh rejected as “baseless, biased and misleading”, said the outlet.
- YOUR FEEDBACK: Please let us know what you thought of Carbon Brief’s coverage last year by completing our annual reader survey. Ten respondents will be chosen at random to receive a CB laptop sticker.
47%
The share of the UK’s electricity supplied by renewables in 2025, more than any other source, according to Carbon Brief analysis.
Latest climate research
- Deforestation due to the mining of “energy transition minerals” is a “major, but overlooked source of emissions in global energy transition” | Nature Climate Change
- Up to three million people living in the Sudd wetland region of South Sudan are currently at risk of being exposed to flooding | Journal of Flood Risk Management
- In China, the emissions intensity of goods purchased online has dropped by one-third since 2000, while the emissions intensity of goods purchased in stores has tripled over that time | One Earth
(For more, see Carbon Brief’s in-depth daily summaries of the top climate news stories on Monday, Tuesday, Wednesday, Thursday and Friday.)
Captured
The US, which has announced plans to withdraw from the UNFCCC, is more responsible for climate change than any other country or group in history, according to Carbon Brief analysis. The chart above shows the cumulative historical emissions of countries since the advent of the industrial era in 1850.
Spotlight
How to think about Africa’s just energy transition
African nations are striving to boost their energy security, while also addressing climate change concerns such as flood risks and extreme heat.
This week, Carbon Brief speaks to the deputy Africa director of the Natural Resource Governance Institute, Ibrahima Aidara, on what a just energy transition means for the continent.
Carbon Brief: When African leaders talk about a “just energy transition”, what are they getting right? And what are they still avoiding?
Ibrahima Aidara: African leaders are right to insist that development and climate action must go together. Unlike high-income countries, Africa’s emissions are extremely low – less than 4% of global CO2 emissions – despite housing nearly 18% of the world’s population. Leaders are rightly emphasising universal energy access, industrialisation and job creation as non-negotiable elements of a just transition.
They are also correct to push back against a narrow narrative that treats Africa only as a supplier of raw materials for the global green economy. Initiatives such as the African Union’s Green Minerals Strategy show a growing recognition that value addition, regional integration and industrial policy must sit at the heart of the transition.
However, there are still important blind spots. First, the distributional impacts within countries are often avoided. Communities living near mines, power infrastructure or fossil-fuel assets frequently bear environmental and social costs without sharing in the benefits. For example, cobalt-producing communities in the Democratic Republic of the Congo, or lithium-affected communities in Zimbabwe and Ghana, still face displacement, inadequate compensation, pollution and weak consultation.
Second, governance gaps are sometimes downplayed. A just transition requires strong institutions (policies and regulatory), transparency and accountability. Without these, climate finance, mineral booms or energy investments risk reinforcing corruption and inequality.
Finally, leaders often avoid addressing the issue of who pays for the transition. Domestic budgets are already stretched, yet international climate finance – especially for adaptation, energy access and mineral governance – remains far below commitments. Justice cannot be achieved if African countries are asked to self-finance a global public good.
CB: Do African countries still have a legitimate case for developing new oil and gas projects, or has the energy transition fundamentally changed what ‘development’ looks like?
IA: The energy transition has fundamentally changed what development looks like and, with it, how African countries should approach oil and gas. On the one hand, more than 600 million Africans lack access to electricity and clean cooking remains out of reach for nearly one billion people. In countries such as Mozambique, Nigeria, Senegal and Tanzania, gas has been framed to expand power generation, reduce reliance on biomass and support industrial growth. For some contexts, limited and well-governed gas development can play a transitional role, particularly for domestic use.
On the other hand, the energy transition has dramatically altered the risks. Global demand uncertainty means new oil and gas projects risk becoming stranded assets. Financing is shrinking, with many development banks and private lenders exiting fossil fuels. Also, opportunity costs are rising; every dollar locked into long-lived fossil infrastructure is a dollar not invested in renewables, grids, storage or clean industry.
Crucially, development today is no longer just about exporting fuels. It is about building resilient, diversified economies. Countries such as Morocco and Kenya show that renewable energy, green industry and regional power trade can support growth without deepening fossil dependence.
So, the question is no longer whether African countries can develop new oil and gas projects, but whether doing so supports long-term development, domestic energy access and fiscal stability in a transitioning world – or whether it risks locking countries into an extractive model that benefits few and exposes countries to future shocks.
CB: What is the hardest truth about Africa’s energy transition that policymakers and international partners are still unwilling to confront?
IA: For me, the hardest truth is this: Africa cannot deliver a just energy transition on unfair global terms. Despite all the rhetoric, global rules still limit Africa’s policy space. Trade and investment agreements restrict local content, industrial policy and value-addition strategies. Climate finance remains fragmented and insufficient. And mineral supply chains are governed largely by consumer-country priorities, not producer-country development needs.
Another uncomfortable truth is that not every “green” investment is automatically just. Without strong safeguards, renewable energy projects and mineral extraction can repeat the same harms as fossil fuels: displacement, exclusion and environmental damage.
Finally, there is a reluctance to admit that speed alone is not success. A rushed transition that ignores governance, equity and institutions will fail politically and socially, and, ultimately, undermine climate goals.
If Africa’s transition is to succeed, international partners must accept African leadership, African priorities and African definitions of development, even when that challenges existing power dynamics in global energy and mineral markets.
Watch, read, listen
CRISIS INFLAMED: In the Brazilian newspaper Folha de São Paulo, columnist Marcelo Leite looked into the climate impact of extracting more oil from Venezuela.
BEYOND TALK: Two Harvard scholars argued in Climate Home News for COP presidencies to focus less on climate policy and more on global politics.
EU LEVIES: A video explainer from the Hindu unpacked what the EU’s carbon border tax means for India and global trade.
Coming up
- 10-12 January: 16th session of the IRENA Assembly, Abu Dhabi
- 13-15 January: Energy Security and Green Infrastructure Week, London
- 13-15 January: The World Future Energy Summit, Abu Dhabi
- 15 January: Uganda general elections
Pick of the jobs
- WRI Polsky Energy Center, global director | Salary: around £185,000. Location: Washington DC; the Hague, Netherlands; New Delhi, Mumbai, or Bengaluru, India; or London
- UK government Advanced Research and Invention Agency, strategic communications director – future proofing our climate and weather | Salary: £115,000. Location: London
- The Wildlife Trusts, head of climate and international policy | Salary: £50,000. Location: London
- Children’s Investment Fund Foundation, senior manager for climate | Salary: Unknown. Location: London, UK
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 9 January 2026: US to exit global climate treaty; Venezuelan oil ‘uncertainty’; ‘Hardest truth’ for Africa’s energy transition appeared first on Carbon Brief.
The Trump administration in the US has announced its intention to withdraw from the UN’s landmark climate treaty, alongside 65 other international bodies that “no longer serve American interests”.
Every nation in the world has committed to tackling “dangerous anthropogenic interference with the climate system” under the 1992 UN Framework Convention on Climate Change (UNFCCC).
During Donald Trump’s second presidency, the US has already failed to meet a number of its UN climate treaty obligations, including reporting its emissions and funding the UNFCCC – and it has not attended recent climate summits.
However, pulling out of the UNFCCC would be an unprecedented step and would mark the latest move by the US to disavow global cooperation and climate action.
Among the other organisations the US plans to leave is the Intergovernmental Panel on Climate Change (IPCC), the UN body seen as the global authority on climate science.
In this article, Carbon Brief considers the implications of the US leaving these bodies, as well as the potential for it rejoining the UNFCCC in the future.
Carbon Brief has also spoken to experts about the contested legality of leaving the UNFCCC and what practical changes – if any – will result from the US departure.
- What is the process for pulling out of the UNFCCC?
- Is it legal for Trump to take the US out of the UNFCCC unilaterally?
- How could the US rejoin the UNFCCC and Paris Agreement?
- What changes when the US withdraws from the UNFCCC?
- What about the US withdrawal from the IPCC?
- What other organisations are affected?
What is the process for pulling out of the UNFCCC?
The Trump administration set out its intention to withdraw from the UNFCCC and the IPCC in a White House presidential memorandum issued on 7 January 2026.
It claims authority “vested in me as president by the constitution and laws of the US” to withdraw the country from the treaty, along with 65 other international and UN bodies.
However, the memo includes a caveat around its instructions, stating:
“For UN entities, withdrawal means ceasing participation in or funding to those entities to the extent permitted by law.”
(In an 8 January interview with the New York Times, Trump said he did not “need international law” and that his powers were constrained only by his “own morality”.)
The US is the first and only country in the world to announce it wants to withdraw from the UNFCCC.
The convention was adopted at the UN headquarters in New York in May 1992 and opened for signatures at the Rio Earth summit the following month. The US became the first industrialised nation to ratify the treaty that same year.
It was ultimately signed by every nation on Earth – making it one of the most ratified global treaties in history.
Article 25 of the treaty states that any party may withdraw by giving written notification to the “depositary”, which is elsewhere defined as being the UN secretary general – currently, António Guterres.
The article, shown below, adds that the withdrawal will come into force a year after a written notification is supplied.
The treaty adds that any party that withdraws from the convention shall be considered as also having left any related protocol.
The UNFCCC has two main protocols: the Kyoto Protocol of 1997 and the Paris Agreement of 2015.
Although former US president Bill Clinton signed the Kyoto Protocol in 1998, its formal ratification faced opposition from the Senate and the treaty was ultimately rejected by his successor, president George W Bush, in 2001.
Domestic opposition to the protocol centred around the exclusion of major developing countries, such as China and India, from emissions reduction measures.
The US did ratify the Paris Agreement, but Trump signed an executive order to take the nation out of the pact for a second time on his first resumed day in office in January 2025.
Is it legal for Trump to take the US out of the UNFCCC unilaterally?
Whether Trump can legally pull the US out of the UNFCCC without the consent of the Senate remains unclear.
The US previously left the Paris Agreement during Trump’s first term.
Both the UNFCCC and the Paris Agreement allow any party to withdraw with a year’s written notice. However, both treaties state that parties cannot withdraw within the first three years of ratification.
As such, the first Trump administration filed notice to exit the Paris Agreement in November 2019 and became the first nation in the world to formally leave a year later – the day after Democrat Joe Biden won the 2020 presidential election.
On his first day in office in 2021, Biden rejoined the Paris Agreement. This took 30 days from notifying the UNFCCC to come into force.
The legalities of leaving the UNFCCC are murkier, due to how it was adopted.
As Michael B Gerrard, director of the Sabin Center for Climate Change Law at Columbia Law School, explains to Carbon Brief, the Paris Agreement was ratified without Senate approval.
Article 2 of the US Constitution says presidents have the power to make or join treaties subject to the “advice and consent” of the Senate – including a two-thirds majority vote (see below).
However, Barack Obama took the position that, as the Paris Agreement “did not impose binding legal obligations on the US, it was not a treaty that required Senate ratification”, Gerrard tells Carbon Brief.
As noted in a post by Jake Schmidt, a senior strategic director at the environmental NGO Natural Resources Defense Council (NRDC), the US has other mechanisms for entering international agreements. It says the US has joined more than 90% of the international agreements it is party to through different mechanisms.
In contrast, George H Bush did submit the UNFCCC to the Senate in 1992, where it was unanimously ratified by a 92-0 vote, ahead of his signing it into law.
Reversing this is uncertain legal territory. Gerrard tells Carbon Brief:
“There is an open legal question whether a president can unilaterally withdraw the US from a Senate-ratified treaty. A case raising that question reached the US Supreme Court in 1979 (Goldwater vs Carter), but the Supreme Court ruled this was a political question not suitable for the courts.”
Unlike ratifying a treaty, the US Constitution does not explicitly specify whether the consent of the Senate is required to leave one.
This has created legal uncertainty around the process.
Given the lack of clarity on the legal precedent, some have suggested that, in practice, Trump can pull the US out of treaties unilaterally.
Sue Biniaz, former US principal deputy special envoy for climate and a key legal architect of the Paris Agreement, tells Carbon Brief:
“In terms of domestic law, while the Supreme Court has not spoken to this issue (it treated the issue as non-justifiable in the Goldwater v Carter case), it has been US practice, and the mainstream legal view, that the president may constitutionally withdraw unilaterally from a treaty, ie without going back to the Senate.”
Additionally, the potential for Congress to block the withdrawal from the UNFCCC and other treaties is unclear. When asked by Carbon Brief if it could play a role, Biniaz says:
“Theoretically, but politically unlikely, Congress could pass a law prohibiting the president from unilaterally withdrawing from the UNFCCC. (The 2024 NDAA contains such a provision with respect to NATO.) In such case, its constitutionality would likely be the subject of debate.”
How could the US rejoin the UNFCCC and Paris Agreement?
The US would be able to rejoin the UNFCCC in future, but experts disagree on how straightforward the process would be and whether it would require a political vote.
In addition to it being unclear whether a two-thirds “supermajority” vote in the Senate is required to leave a treaty, it is unclear whether rejoining would require a similar vote again – or if the original 1992 Senate consent would still hold.
Citing arguments set out by Prof Jean Galbraith of the University of Pennsylvania law school, Schmidt’s NRDC post says that a future president could rejoin the convention within 90 days of a formal decision, under the merit of the previous Senate approval.
Biniaz tells Carbon Brief that there are “multiple future pathways to rejoining”, adding:
“For example, Prof Jean Galbraith has persuasively laid out the view that the original Senate resolution of advice and consent with respect to the UNFCCC continues in effect and provides the legal authority for a future president to rejoin. Of course, the Senate could also give its advice and consent again. In any case, per Article 23 of the UNFCCC, it would enter into force for the US 90 days after the deposit of its instrument.”
Prof Oona Hathaway, an international law professor at Yale Law School, believes there is a “very strong case that a future president could rejoin the treaty without another Senate vote”.
She tells Carbon Brief that there is precedent for this based on US leaders quitting and rejoining global organisations in the past, explaining:
“The US joined the International Labour Organization in 1934. In 1975, the Ford administration unilaterally withdrew, and in 1980, the Carter administration rejoined without seeking congressional approval.
“Similarly, the US became a member of the United Nations Educational, Scientific and Cultural Organization (UNESCO) in 1946. In the 1980s, the Reagan administration unilaterally withdrew the US. The Bush administration rejoined UNESCO in 2002, but in 2019 the Trump administration once again withdrew. The Biden administration rejoined in 2023, and the Trump Administration announced its withdrawal again in 2025.”
But this “legal theory” of a future US president specifically re-entering the UNFCCC “based on the prior Senate ratification” has “never been tested in court”, Prof Gerrard from Columbia Law School tells Carbon Brief.
Dr Joanna Depledge, an expert on global climate negotiations and research fellow at the University of Cambridge, tells Carbon Brief:
“Due to the need for Senate ratification of the UNFCCC (in my interpretation), there is no way back now for the US into the climate treaties. But there is nothing to stop a future US president applying [the treaty] rules or – what is more important – adopting aggressive climate policy independently of them.”
If it were required, achieving Senate approval to rejoin the UNFCCC would take a “significant shift in US domestic politics”, public policy professor Thomas Hale from the University of Oxford notes on Bluesky.
Rejoining the Paris Agreement, on the other hand, is a simpler process that the US has already undertaken in recent years. (See: Is it legal for Trump to take the US out of the UNFCCC unilaterally?) Biniaz explains:
“In terms of the Paris Agreement, a party to that agreement must also be a party to the UNFCCC (Article 20). Assuming the US had rejoined the UNFCCC, it could rejoin the Paris Agreement as an executive agreement (as it did in early 2021). The agreement would enter into force for the US 30 days after the deposit of its instrument (Article 21).”
The Center for Climate and Energy Solutions, an environmental non-profit, explains that Senate approval was not required for Paris “because it elaborates an existing treaty” – the UNFCCC.
What changes when the US withdraws from the UNFCCC?
US withdrawal from the UNFCCC has been described in media coverage as a “massive hit” to global climate efforts that will “significantly limit” the treaty’s influence.
However, experts tell Carbon Brief that, as the Trump administration has already effectively withdrawn from most international climate activities, this latest move will make little difference.
Moreover, Depledge tells Carbon Brief that the international climate regime “will not collapse” as a result of US withdrawal. She says:
“International climate cooperation will not collapse because the UNFCCC has 195 members rather than 196. In a way, the climate treaties have already done their job. The world is already well advanced on the path to a lower-carbon future. Had the US left 10 years ago, it would have been a serious threat, but not today. China and other renewable energy giants will assert even more dominance.”
Depledge adds that while the “path to net-zero will be longer because of the drastic rollback of domestic climate policy in the US”, it “won’t be reversed”.
Technically, US departure from the UNFCCC would formally release it from certain obligations, including the need to report national emissions.
As the world’s second-largest annual emitter, this is potentially significant.
“The US withdrawal from the UNFCCC undoubtedly impacts on efforts to monitor and report global greenhouse gas emissions,” Dr William Lamb, a senior researcher at the Potsdam Institute for Climate Impact Research (PIK), tells Carbon Brief.
Lamb notes that while scientific bodies, such as the IPCC, often use third-party data, national inventories are still important. The US already failed to report its emissions data last year, in breach of its UNFCCC treaty obligations.
Robbie Andrew, senior researcher at Norwegian climate institute CICERO, says that it will currently be possible for third-party groups to “get pretty close” to the carbon dioxide (CO2) emissions estimates previously published by the US administration. However, he adds:
“The further question, though, is whether the EIA [US Energy Information Administration] will continue reporting all of the energy data they currently do. Will the White House decide that reporting flaring is woke? That even reporting coal consumption is an unnecessary burden on business? I suspect the energy sector would be extremely unhappy with changes to the EIA’s reporting, but there’s nothing at the moment that could guarantee anything at all in that regard.”
Andrew says that estimating CO2 emissions from energy is “relatively straightforward when you have detailed energy data”. In contrast, estimating CO2 emissions from agriculture, land use, land-use change and forestry, as well as other greenhouse gas emissions, is “far more difficult”.
The US Treasury has also announced that the US will withdraw from the UN’s Green Climate Fund (GCF) and give up its seat on the board, “in alignment” with its departure from the UNFCCC. The Trump administration had already cancelled $4bn of pledged funds for the GCF.
Another specific impact of US departure would be on the UNFCCC secretariat budget, which already faces a significant funding gap. US annual contributions typically make up around 22% of the body’s core budget, which comes from member states.
However, as with emissions data and GCF withdrawal, the Trump administration had previously indicated that the US would stop funding the UNFCCC.
In fact, billionaire and UN special climate envoy Michael Bloomberg has already committed, alongside other philanthropists, to making up the US shortfall.
Veteran French climate negotiator Paul Watkinson tells Carbon Brief:
“In some ways the US has already suspended its participation. It has already stopped paying its budget contributions, it sent no delegation to meetings in 2025. It is not going to do any reporting any longer – although most of that is now under the Paris Agreement. So whether it formally leaves the UNFCCC or not does not change what it is likely to do.”
Dr Joanna Depledge tells Carbon Brief that she agrees:
“This is symbolically and politically huge, but in practice it makes little difference, given that Trump had already announced total disengagement last year.”
The US has a history of either leaving or not joining major environmental treaties and organisations, such as the Paris Agreement and the Kyoto Protocol. (See: What is the process for pulling out of the UNFCCC?)
Dr Jennifer Allan, a global environmental politics researcher at Cardiff University, tells Carbon Brief:
“The US has always been an unreliable partner…Historically speaking, this is kind of more of the same.”
The NRDC’s Jake Schmidt tells Carbon Brief that he doubts US absence will lead to less progress at UN climate negotiations. He adds:
“[The] Trump team would have only messed things up, so not having them participate will probably actually lead to better outcomes.”
However, he acknowledges that “US non-participation over the long-term could be used by climate slow-walking countries as an excuse for inaction”.
Biniaz tells Carbon Brief that the absence of the US is unlikely to unlock reform of the UN climate process – and that it might make negotiations more difficult. She says:
“I don’t see the absence of the US as promoting reform of the COP process. While the US may have had strong views on certain topics, many other parties did as well, and there is unlikely to be agreement among them to move away from the consensus (or near consensus) decision-making process that currently prevails. In fact, the US has historically played quite a significant ‘broker’ role in the negotiations, which might actually make it more difficult for the remaining parties to reach agreement.”
After leaving the UNFCCC, the US would still be able to participate in UN climate talks as an observer, albeit with diminished influence. (It is worth noting that the US did not send a delegation to COP30 last year.)
There is still scope for the US to use its global power and influence to disrupt international climate processes from the outside.
For example, last year, the Trump administration threatened nations and negotiators with tariffs and withdrawn visa rights if they backed an International Maritime Organization (IMO) effort to cut shipping emissions. Ultimately, the measures were delayed due to a lack of consensus.
(Notably, the IMO is among the international bodies that the US has not pledged to leave.)
What about the US withdrawal from the IPCC?
As a scientific body, rather than a treaty, there is no formal mechanism for “withdrawing” from the IPCC. In its own words, the IPCC is an “organisation of governments that are members of the UN or World Meteorological Organization” (WMO).
Therefore, just being part of the UN or WMO means a country is eligible to participate in the IPCC. If a country no longer wishes to play a role in the IPCC, it can simply disengage from its activities – for example, by not attending plenary meetings, nominating authors or providing financial support.
This is exactly what the US government has been doing since last year.
Shortly before the IPCC’s plenary meeting for member governments – known as a “session” – in Hangzhou, China, in March 2025, reports emerged that US officials had been denied permission to attend.
In addition, the contract for the technical support unit for Working Group III (WG3) was terminated by its provider, NASA, which also eliminated the role of chief scientist – the position held by WG3 co-chair Dr Kate Cavlin.
(Each of the IPCC’s three “working groups” has a technical support unit, or TSU, which provides scientific and operational support. These are typically “co-located” between the home countries of a working group’s two co-chairs.)
The Hangzhou session was the first time that the US had missed a plenary since the IPCC was founded in 1988. It then missed another in Lima, Peru, in October 2025.
Although the US government did not nominate any authors for the IPCC’s seventh assessment cycle (AR7), US scientists were still put forward through other channels. Analysis by Carbon Brief shows that, across the three AR7 working group reports, 55 authors are affiliated with US institutions.
However, while IPCC authors are supported by their institutions – they are volunteers and so are not paid by the IPCC – their travel costs for meetings are typically covered by their country’s government. (For scientists from developing countries, there is financial support centrally from the IPCC.)
Prof Chris Field, co-chair of Working Group II during the IPCC’s fifth assessment (AR5), tells Carbon Brief that a “number of philanthropies have stepped up to facilitate participation by US authors not supported by the US government”.
The US Academic Alliance for the IPCC – a collaboration of US universities and research institutions formed last year to fill the gap left by the government – has been raising funds to support travel.
In a statement reacting to the US withdrawal, IPCC chair Prof Sir Jim Skea said that the panel’s focus remains on preparing the reports for AR7:
“The panel continues to make decisions by consensus among its member governments at its regular plenary sessions. Our attention remains firmly on the delivery of these reports.”
The various reports will be finalised, reviewed and approved in the coming years – a process that can continue without the US. As it stands, the US government will not have a say on the content and wording of these reports.
Field describes the US withdrawal as a “self-inflicted wound to US prestige and leadership” on climate change. He adds:
“I don’t have a crystal ball, but I hope that the US administration’s animosity toward climate change science will lead other countries to support the IPCC even more strongly. The IPCC is a global treasure.”
The University of Edinburgh’s Prof Gabi Hegerl, who has been involved in multiple IPCC reports, tells Carbon Brief:
“The contribution and influence of US scientists is presently reduced, but there are still a lot of enthusiastic scientists out there that contribute in any way they can even against difficult obstacles.”
On Twitter, Prof Jean-Pascal van Ypersele – IPCC vice-chair during AR5 – wrote that the US withdrawal was “deeply regrettable” and that to claim the IPCC’s work is contrary to US interests is “simply nonsensical”. He continued:
“Let us remember that the creation of the IPCC was facilitated in 1988 by an agreement between Ronald Reagan and Margaret Thatcher, who can hardly be described as ‘woke’. Climate and the environment are not a matter of ideology or political affiliation: they concern everyone.”
Van Ypersele added that while the IPCC will “continue its work in the service of all”, other countries “will have to compensate for the budgetary losses”.
The IPCC’s most recent budget figures show that the US did not make a contribution in 2025.
Carbon Brief analysis shows that the US has provided around 30% of all voluntary contributions in the IPCC’s history. Totalling approximately $67m (£50m), this is more than four times that of the next-largest direct contributor, the EU.
However, this is not the first time that the US has withdrawn funding from the IPCC. During Trump’s first term of office, his administration cut its contributions in 2017, with other countries stepping up their funding in response. The US subsequently resumed its contributions.
At its most recent meeting in Lima, Peru, in October 2025, the IPCC warned of an “accelerating decline” in the level of annual voluntary contributions from countries and other organisations, reported the Earth Negotiations Bulletin. As a result, the IPCC invited member countries to increase their donations “if possible”.
What other organisations are affected?
In addition to announcing his plan to withdraw the US from the UNFCCC and the IPCC, Trump also called for the nation’s departure from 16 other organisations related to climate change, biodiversity and clean energy.
These include:
- The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) – the biodiversity equivalent of the IPCC.
- Intergovernmental Forum on Mining, Minerals, Metals and Sustainable Development – a voluntary group of more than 80 countries aiming to make the mining sector more sustainable.
- UN Energy – the principal UN organisation for international collaboration on energy.
- UN Oceans – a UN mechanism responsible for overseeing the International Seabed Authority (ISA) and other UN agencies related to ocean and coastal issues.
- UN Water – the UN agency responsible for water and sanitation.
- UN Collaborative Programme on Reducing Emissions from Deforestation and Forest Degradation in Developing Countries (UN-REDD) – a UN collaborative initiative for creating financial incentives for protecting forests.
- International Renewable Energy Agency – an intergovernmental organisation supporting countries in their transition to renewable energy.
- 24/7 Carbon-Free Energy Compact – a UN initiative launched in 2021 pushing governments, companies and organisations to achieve 100% low-carbon electricity generation.
- Commission for Environmental Cooperation – an organisation aimed at conserving North America’s natural environment.
- Inter-American Institute for Global Change Research – an intergovernmental organisation supported by 19 countries in North and South America for the support of planetary change research.
- International Energy Forum – an intergovernmental platform for dialogue among countries, industry and experts.
- International Solar Alliance – an organisation supporting the development of solar power and the phaseout of fossil fuels.
- International Tropical Timber Organization – an organisation aimed at protecting tropical forest resources.
- International Union for Conservation of Nature – an international nature conservation organisation and authority on the state of biodiversity loss.
- Renewable Energy Policy Network for the 21st Century – a global policy forum for renewable energy leadership.
- Secretariat of the Pacific Regional Environment Programme – a regional organisation aimed at protecting the Pacific’s environment.
As well as participating in the work of these organisations, the US is also a key source of funding for many of them – leaving their futures uncertain.
In a letter to members seen by Carbon Brief, IPBES chair and Kenyan ecologist, Dr David Obura, described Trump’s move as “deeply disappointing”.
He said that IPBES “has not yet received any formal notification” from the US, but “anticipates that the intention expressed to withdraw will mean that the US will soon cease to be a member of IPBES”, adding:
“The US is a founding member of IPBES and scientists, policymakers and stakeholders – including Indigenous peoples and local communities – from the US have been among the most engaged contributors to the work of IPBES since its establishment in 2012, making valuable contributions to objective science-based assessments of the state of the planet, for people and nature.
“The contribution of US experts ranges from leading landmark assessment reports, to presiding over negotiations, serving as authors and reviewers, as well as helping to steer the organisation both scientifically and administratively.”
Despite being a party to IPBES until now, the US has never been a signatory to the UN Convention on Biological Diversity (CBD), the nature equivalent of the UNFCCC.
It is one of only two nations not to sign the convention, with the other being the Holy See, representing the Vatican City.
The lack of US representation at the CBD has not prevented countries from reaching agreements. In 2022, countries gathered under the CBD adopted the Kunming-Montreal Global Biodiversity Framework, often described as the “Paris Agreement for nature”.
However, some observers have pointed to the lack of US involvement as one of the reasons why biodiversity loss has received less international attention than climate change.
The post Q&A: What Trump’s US exit from UNFCCC and IPCC could mean for climate action appeared first on Carbon Brief.
Q&A: What Trump’s US exit from UNFCCC and IPCC could mean for climate action
Greenhouse Gases
Analysis: World’s biggest historic polluter – the US – is pulling out of UN climate treaty
The US, which has announced plans to withdraw from the global climate treaty – the UN Framework Convention on Climate Change (UNFCCC) – is more historically responsible for climate change than any other country or group.
Carbon Brief analysis shows that the US has emitted a total of 542bn tonnes of carbon dioxide (GtCO2) since 1850, by burning fossil fuels, cutting down trees and other activities.
This is the largest contribution to the Earth’s warming climate by far, as shown in the figure below, with China’s 336GtCO2 significantly behind in second and Russia in third at 185GtCO2.
The US is responsible for more than a fifth of the 2,651GtCO2 that humans have pumped into the atmosphere between 1850 and 2025 as a result of fossil fuels, cement and land-use change.
China is responsible for another 13%, with the 27 nations of the EU making up another 12%.
In total, these cumulative emissions have used up more than 95% of the carbon budget for limiting global warming to 1.5C and are the predominant reason the Earth is already nearly 1.5C hotter than in pre-industrial times.
The US share of global warming is even more disproportionate when considering that its population of around 350 million people makes up just 4% of the global total.
On the basis of current populations, the US’s per-capita cumulative historical emissions are around 7 times higher than those for China, more than double the EU’s and 25 times those for India.
The US’s historical emissions of 542GtCO2 are larger than the combined total of the 133 countries with the lowest cumulative contributions, a list that includes Saudi Arabia, Spain and Nigeria. Collectively, these 133 countries have a population of more than 3 billion people.
See Carbon Brief’s previous detailed analysis of historical responsibility for climate change for more details on the data sources and methodology, as well as consumption-based emissions.
Additionally, in 2023, Carbon Brief published an article that looked at the “radical” impact of reassigning responsibility for historical emissions to colonial rulers in the past.
This approach has a very limited impact on the US, which became independent before the vast majority of its historical emissions had taken place.
The post Analysis: World’s biggest historic polluter – the US – is pulling out of UN climate treaty appeared first on Carbon Brief.
Analysis: World’s biggest historic polluter – the US – is pulling out of UN climate treaty
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