“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
This week our powerful Pacific team is in Palau for the Pacific Islands Forum Leaders Meeting. This is a major moment in our campaigns for Pacific climate justice and to stop deep sea mining. So what’s it all about, what can we expect over the coming days, and why is this year’s meeting in particular so important? Read on to find out!
*Pawa is Melanesian word meaning collective power.
Meet Moemoana Schwenke, our Pacific Climate Campaigner
“When you love something deeply, you do everything you can to protect it.”
What is the Pacific Islands Forum (PIF)?
The Pacific Islands Forum, or ‘PIF’, is our region’s most important political organisation. It is where countries of the Pacific — including Australia and New Zealand — come together to collaborate on shared challenges and to set collective goals.
The PIF Leaders Meeting is an annual weeklong event that includes a dedicated meeting of the Pacific’s small island developing states (PSIDS), many special side events organised by Pacific civil society, the leaders’ meeting itself, and more. At the end of the week, leaders issue a Forum Communiqué, capturing what they have agreed on, their shared priorities and the actions they will take together.
This year’s meeting is being held in the beautiful northern Pacific nation of Palau, the same place our Pacific team gathered back in January to plan for the year.
What’s at stake this year?
Climate change has dominated the PIF for decades. Pacific leaders have been crystal clear it is their number one priority, and the annual gathering is the moment they can exert maximum pressure on Australia over its fossil fuel record.
The voyage to COP31
This year’s meeting comes less than three months before COP31, where Australia will take on the role of President of Negotiations — a role it has committed to undertaking in partnership with the Pacific — and less than a month before the ‘Pacific Pre-COP’, to be held in Fiji and Tuvalu.
Following a fraught round of mid-year negotiations in Bonn, PIF leaders will need to set out a clear vision and priorities for COP31. These include accelerating a just global transition away from fossil fuels, defending science as the foundation of international climate cooperation, and increasing the availability and accessibility of finance for renewable energy and climate adaptation.
Accountability for Australian fossil fuel exports
Since the last PIF Leaders Meeting, Australia has signed the Belém Declaration on the Transition Away from Fossil Fuels. The declaration reaffirmed the legally binding commitment to help limit global warming to 1.5°C and recognised that this is incompatible with new fossil fuel production. Yet, Australia has continued to approve new coal and gas projects, including at least five since the last PIF Leaders Meeting.
What is Greenpeace doing?
We’re going big this year, taking six members of our team to Palau to support Pacific leaders to hold the line, hold Australia accountable, and show the world what’s at stake. We’ll lobby leaders, hold press conferences, share our messages with the world, and support our incredible local partners in Palau.
How can you get involved?
PIF is the first in a drumbeat of major moments where we’ll be carrying the voices of the Pacific to the world. Come October we’ll be voyaging to Fiji on our ship Oceania for the Pacific Pre-COP, and in November we’ll be off to Antalya for the world’s climate negotiations (COP31).
Learn more about the Pacific way to a fossil fuel free future by checking out our report and exhibition.
Follow our journey, and check back here for more ways to join the movement for climate justice. Together we have the pawa!
Gill Einhorn is head of the Forest Future Alliance and Natalie Çilem is community lead of the Global Wildfire Leadership Network.
Wildfires have devastated communities across the world this summer, claiming lives, displacing thousands of people and leaving billions in economic damage in their wake. In Europe alone, wildfires have already caused an estimated €19 billion in losses this year.
They are an economic, financial and public health challenge that is growing faster than many governments and markets are prepared for – and exposing the real costs of poor land management.
A system built for recovery, not resilience
Far more money is currently spent responding to the disastrous effects of wildfires than preventing them in the first place. The United Nations Environment Programme estimates that more than half of wildfire-related spending goes towards response, while planning receives only around 0.2 percent. This problem is not limited to wildfires; over 95 percent of disaster aid between 2005 and 2017 was allocated to response, and less than 4 percent was directed towards prevention or preparedness.
Forests are critical, but without investment in how land is managed and protected, their value is neither stable nor guaranteed. Protecting forests requires investing not only in conservation, but in the conditions that keep forests standing.
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Each dollar invested in wildfire-resistant construction could save around $210 in avoided future economic losses, according to a report by the World Economic Forum and Forest Future Alliance. Despite this evidence that prevention can significantly reduce future costs, wildfire resilience remains chronically underfunded.
This spending discrepancy is creating significant challenges for insurers, asset owners and financial institutions. Global insured losses from natural catastrophes reached $107 billion in 2025, with wildfires, floods and storms accounting for 92 percent of claims.
In this context, insurers are reassessing where and how they are willing to underwrite risk. Around 56 percent of global wildfire losses between 2000 and 2023 were uninsured. In some high-risk areas, insurers are scaling back coverage altogether, leaving homeowners, businesses and governments to shoulder a growing share of the costs – making it increasingly difficult to break even.
Proven solutions are already paying off
In many regions, wildfires are driven not by natural causes but by the deliberate clearing of land for agriculture. Degraded landscapes are becoming drier, more flammable and increasingly vulnerable to catastrophic loss, creating a vicious cycle of deforestation, economic damage and rising emissions.
The answer is not simply stronger firefighting capacity. Governments, investors and businesses must work together to shift capital upstream into prevention, resilience and long-term landscape stewardship of healthy forests. That means planting appropriately, investing in heat-resistant species, exploring approaches that minimise fire footprints through active management, and exploring the AI and technology solutions that are burgeoning.
Solutions to this already exist and are proven to have an impact. Following devastating wildfires year-on-year, Portugal shifted its approach to wildfire management, increasing prevention spending within its national rural fire management system from around 20 percent in 2017 to approximately 60 percent in 2022. While many countries remain locked in a reactive cycle of disaster response, public policy can shift investment upstream and make resilience a priority before fires occur.
Indigenous communities have long used proactive land stewardship to reduce wildfire risk while supporting healthy and productive landscapes. For example, the Cheslatta Carrier Nation in British Columbia traditionally managed fuels through cultural fire practices but now implements mechanised fuel removal methods under commercial agreements. By combining Indigenous stewardship with sustainable forest management, Cheslatta is generating community benefits while also boosting wildfire prevention.
Resilience can also be strengthened through finance and technology. FireSat, a partnership led by Earth Fire Alliance with Google.org, the Gordon and Betty Moore Foundation and Muon, is a satellite constellation designed for rapid wildfire detection. Scanning every 20 minutes, it can detect fires 400 times smaller than current systems and track them through smoke and darkness in almost real time. In California alone, FireSat could prevent up to 350,000 acres from burning each year. It has recently received significant new investments allowing it to expand towards a constellation of more than 50 satellites that will monitor every point on Earth every 20 minutes or less.
In Brazil’s Pantanal, the Embrace the Forest initiative uses AI-powered detection towers across 2.5 million hectares to support earlier intervention and faster response. During the severe 2024 fire season, the initiative contributed to a 40 percent reduction in burned area compared to 2020.
These examples illustrate what is possible when resilience is treated as an investment priority rather than a recovery cost. But we must ensure funding for these measures is scaled before disaster strikes. Initiatives like the Global Wildfire Leadership Network (GWLN) are key, bringing together corporate decision-makers, investors, insurers, governments and Indigenous leaders to direct investment towards prevention and align finance, technology and stewardship to protect nature, safeguard communities and strengthen future economic stability. With a goal of doing more together than the sum of our parts, the network focuses on Forest Future Alliance GWLN Solutions Labs – where partners sign up with the intent to collaborate.
Rewarding prevention
Financial incentives must be created that reward prevention. This can be done by scaling public-private partnerships, supporting long-term landscape stewardship, investing in community capacity including Indigenous wisdom and technology. Ultimately, our terrestrial natural reserves are critical infrastructure that support resilient economies and thriving communities.
One in three people are dependent on forest services, goods and economic opportunities for survival, so it’s in all our interests to protect what we have. Forests support cooling, water and food security – and are a very cost-effective way of removing carbon dioxide from the atmosphere, where done appropriately.
UN chief warns climate crisis “in overdrive” as El Niño threatens to fuel the fire
No sector can solve this challenge alone. The benefits of wildfire resilience are shared across communities, governments, insurers, investors, utilities and businesses. A single intervention can protect homes and livelihoods, reduce insurance claims, secure water supplies and lower future public costs. Because the benefits are shared, the solutions must be too. Coalitions of actors can take proven approaches further than any one individual or organisation could alone.
As wildfires continue to burn at an unprecedented scale, the opportunity now is to roll out solutions, shift investment upstream and build a future where resilience, rather than recovery, becomes the foundation of thriving economies.
The post From firefighting to future-proofing: Preventing wildfires must be the priority appeared first on Climate Home News.
From firefighting to future-proofing: Preventing wildfires must be the priority
Methane is a powerful greenhouse gas and the second-largest contributor to global warming after carbon dioxide (CO2).
Methane traps heat in the atmosphere more efficiently than CO2, but has a significantly shorter lifespan, fading after just a few decades.
Therefore, reducing emissions of methane – a gas primarily produced by agriculture, fossil fuels and waste management – is a powerful option for limiting global warming in the near-term.
Yet climate strategies and models often only focus on CO2, or combine all greenhouse gases into one metric known as “CO2 equivalent”.
The latter approach makes reducing methane emissions dependent on modelling choices and assumptions about the “equivalence” of methane and CO2.
It hides the opportunities and challenges linked to methane’s high warming and short lifetime.
In a new study, published in Communications Earth & Environment, we offer a different perspective that “decouples” CO2 and methane reduction and takes global warming limits as a starting point for determining the required level of methane cuts.
We show that, even under the most ambitious existing national net-zero targets, an absence of methane reduction leads to peak warming that exceeds 1.85C above pre-industrial levels.
The study highlights that, to limit peak warming to well-below 2C, net-zero CO2 targets must be complemented by stringent methane emissions cuts.
CO2 equivalent
How much methane corresponds to one tonne of CO2?
The question is as difficult to answer as: ‘how much spaghetti equals a chicken?’ You could compare the two meals according to their calories, protein content or cost. Each metric can be convenient, but is only valid for that specific comparison – no amount of spaghetti is the same as a chicken.
The same is true for the conversion of emissions of methane and other gases to CO2-equivalent emissions. It can be convenient, as it allows different gases to be compared or combined into a single number. This is why the metric is used in climate targets or evaluating the effectiveness of different mitigation options.
But, because methane and CO2 have different atmospheric lifetimes and warming properties, any conversion is only valid for a chosen time horizon and a chosen baseline.
Depending on the assumptions baked into calculations, methane mitigation can either appear as an immediate priority or framed as almost unnecessary.
There are a number of metrics that scientists use to convert greenhouse gases – whether methane, hydrofluorocarbons or nitrous oxide – into CO2-equivalent emissions:
- “GWP20” measures how much heat a greenhouse gas traps in the atmosphere over a 20-year period, relative to CO2. It emphasises urgent methane mitigation but has been criticised for its implicit discounting of future damages.
- “GWP100” looks at a 100-year timeline. It gives more weight to long-term warming and is used in “integrated assessment models” (IAMs) used by scientists, national emission reporting to the UN and by the GHG Protocol used by companies.
- “GWP*” considers the rate of emissions, rather than warming over a fixed time horizon. Under GWP*, very limited methane reductions bring CO2-equivalent emissions to zero, meaning remaining methane emissions can be designated as causing “no additional warming”. (This interpretation remains controversial as it assumes the continuation of historical levels of warming.)
IAMs are the tools used to generate future emissions scenarios. Because they combine CO2 and methane emissions, the impact of methane emission cuts alone is difficult to isolate in existing emission scenarios.
IAM-generated scenarios also assume mitigation decisions driven by costs. Combinations of CO2 and methane emission pathways that are not purely cost-effective are, therefore, not represented, even though climate policy is messy and emission pathways are rarely cost-effective in the real world.
Only a few countries – including Japan, Mexico and South Korea – specify methane mitigation targets.
A different approach
In our study, we separate CO2 and methane emissions and treat them as independent.
Instead of choosing a conversion method, we suggest that states and organisations set a limit on peak global warming first, then, based on their existing net-zero targets, determine the minimum compatible methane reduction target.
Companies and countries around the world have set net-zero targets focused on CO2, as well as those that include all greenhouse gases. As a result, our research looks at the necessary methane reductions for both types of goal. We consider scenarios where companies or countries deliver linear – in other words, steady – emissions reductions to reach net-zero.
Using a simple climate model, we systematically combined methane and CO2 (or greenhouse gas) mitigation pathways starting in 2025 and calculated peak warming.
The figure below shows how peak warming depends on both the year of reaching net-zero CO2 and the level of methane cuts.
The blue arrows in the figure show that to limit warming to 1.7C under a 2050 net-zero CO2 scenario, methane emissions would need to fall by at least 69% by 2050, relative to 2020.
Our research also finds that, if an organisation or country’s 2050 net zero-target covers all greenhouse gases, its methane emissions would need to fall by 63% instead.
However, under current policies, methane emissions are expected to increase by around 20% by 2050, relative to 2020. We find that this pathway would result in peak warming above 2C by 2050 – even if global CO2 emissions were to reach net-zero by that date (see purple bar on the right-hand side of the figure above).
The figure also shows how, if methane emissions remained at 2020 levels and net-zero CO2 was delivered by 2040 or later, warming would exceed 1.85C. This level of warming is above what has been argued as consistent with the Paris Agreement’s “well-below” 2C limit.
Conversely, cutting methane emissions by around one-third – in line with the Global Methane Pledge target for 2030 – could reduce peak warming by 0.15C, of which 0.05C could be delivered by interventions that come at no net cost. These are shown by the orange and red bars, respectively, on the figure above.
The table below highlights the minimum compatible methane cuts for three different peak warming levels and net-zero CO2 or greenhouse-gas emission targets.
| Peak warming | Year of net-zero CO2 emissions | Year of net-zero greenhouse-gas emissions | ||||
| 2050 | 2060 | 2100 | 2050 | 2060 | 2100 | |
| 1.7C | -69% | – | – | -63% | – | – |
| 1.8C | -32% | -56% | – | -11% | -47% | – |
| 2C | +8% | -8% | -83% | >50% | +33% | -78% |
Minimum methane emission reductions between 2020 and the year of net-zero emissions, consistent with peak warming of 1.7C, 1.8C, and 2.0C at 50% likelihood, assuming linear emission trajectories. For some net-zero targets and peak warming levels, there are no compatible methane mitigation targets (indicated by “–”).
Remaining carbon budget
The global carbon budget refers to the amount of cumulative CO2 emissions allowable while still meeting a particular global warming threshold.
The 2021 climate science report from the Intergovernmental Panel on Climate Change (IPCC) and a 2023 Nature study estimated that, by 2025, the remaining carbon budget for holding warming to 2C would be around 1,000-1,150bn tonnes of CO2 (GtCO2).
We find that these estimates are founded on the assumption of methane reductions of 27-35% by 2050, relative to a 2020 baseline. (A 2024 Communications Earth & Environment study reached similar conclusions.)
Under the GWP* metric, where methane emissions are only cut to maintain “no additional warming”, the remaining carbon budget would be constrained. The best estimate of a 2C budget shrinks by around 30% to approximately 750GtCO2.
Finally, if methane emissions are not cut at all in the future, our findings suggest that the remaining carbon budget for 1.7C of global warming has, in effect, already been exhausted.
Our analysis shows how peak warming depends on both CO2 and methane reduction – and how methane-specific targets can help refine existing net-zero targets.
Crucially, we show that complementing net-zero CO2 targets with stringent methane cuts is necessary to limit peak warming to well-below 2C.
Weber, K. et al. (2026) Limiting warming by CO2 and methane mitigation in an expanded scenario space, Communications Earth & Environment, doi:10.1038/s43247-026-03832-1
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The post Guest post: Why tough methane cuts are crucial for keeping warming ‘well-below’ 2C appeared first on Carbon Brief.
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