Developing countries are receiving just a fraction of the international finance they need to prepare citizens and adapt infrastructure for escalating climate impacts.
That is according to the latest adaptation gap report from the UN Environment Programme (UNEP), which calculates that developing nations will need more than $310bn annually between now and 2035 to prepare for the impacts of climate change.
And yet, in 2023, developed nations provided just $26bn in international adaptation finance to developing nations, according to the report.
UNEP warns that, under current trends, developed nations are on track to miss their goal – agreed at the COP26 climate summit in Glasgow – of doubling 2019 international adaptation finance by 2025.
It cautions that countries’ more recent climate-finance pledge for 2035 – the new collective quantified goal (NCGQ) – will be “insufficient” to meet adaptation finance needs.
The UN report – entitled, “Running on empty: The world is gearing up for climate resilience without the money to get there” – also explores how countries are integrating adaptation priorities into national climate plans, policies and practices.
It finds that 87% of countries have at least one national adaptation plan or strategy in place, but warns that gaps remain in the implementation of measures.
Inger Andersen, the executive director of UNEP, says: “Even amid tight budgets and competing priorities, the reality is simple: if we do not invest in adaptation now, we will face escalating costs every year.”
Below, Carbon Brief summarises some of the key takeaways from the report.
- Developed countries are on track to miss their 2025 adaptation finance goal
- Developing nations’ adaptation finance needs are 12 times greater than current flows
- A majority of countries have a national adaptation plan or strategy in place
- Implementation of adaptation measures is progressing – but gaps remain
- The NCQG is insufficient on its own to meet adaptation finance needs
Developed countries are on track to miss their 2025 adaptation finance goal
Climate change adaptation refers to a range of measures that reduce society’s and infrastructure’s vulnerability to climate change, from planting crop varieties that can withstand greater heat through to building stronger defences against floods.
Spending from the public funds of developed nations is a key source of finance for these actions in developing nations, especially for low-income countries that are vulnerable to climate impacts.
Under Article 9 of the Paris Agreement, developed countries agreed to achieve a “balance” in the amount of climate finance raised for emissions reduction and adaptation. However, more money has been raised for cutting emissions than preparing for climate impacts.
UNEP’s adaptation gap report notes that, in 2023, the amount of public money channelled to developing countries from richer nations for adaptation measures fell.
In total, developed countries raised $25.9bn in international adaptation finance – marking a decline on the $27.9bn recorded in 2022.
The report authors attribute the fall to a decline in funding from multilateral development banks, such as the World Bank, which provided more than half – 57% – of international adaptation finance.
The table below shows how adaptation finance provided by developed countries for developing countries (orange) dipped in 2023 – despite an uptick in climate finance as a whole.
The UN warns that, if current trends continue, developed nations are set to miss their goal of doubling 2019 adaptation finance flows by 2025.
This goal – set out in the Glasgow Climate Pact agreed at the COP26 climate summit in 2021 – commits developed nations to providing $40bn in adaptation funding for developing nations by 2025.
Official climate-finance figures from the Organisation for Economic Co-operation and Development (OECD) for 2025 will not be available for several years. However, the report notes that, over 2019-23, international adaptation finance grew at a compound rate of 7% – falling short of the 12% rate required to meet the Glasgow Climate Pact goal.
Cuts to international aid budgets since 2023 are also threatening the Glasgow Climate Pact goal, according to the report authors. They note that, globally, foreign aid fell by 9% in 2024 and predict that reductions announced in 2025 are “likely” to lead to a further 9-17% decline.
Meanwhile, countries’ more recent pledge to help raise $300bn a year by 2035 for both tackling and adapting to climate change – set out in the new collective quantified goal for climate finance (NCQG), agreed last year at COP29 in Baku – is also under threat, according to the report.
In the introduction of the report, UNEP’s Anderson writes:
“While the numbers for 2024 and 2025 are not yet available, one thing is clear: unless trends in adaptation financing do not turn around, which currently seems unlikely, the Glasgow Climate Pact goal will not be achieved, the NCQG will not be achieved and many more people will suffer needlessly.”
‘Adaptation investment trap’
The report also breaks down international adaptation finance in 2023 by funding type. It finds that that 70% was either grants, which allow countries to address climate impacts without exacerbating debt, or “concessional” loans, which are provided at below market rate.
However, it notes that “non-consessional” finance – which is provided at, or near, market rates – is on the rise, growing at an annual compound rate of 7% over 2019-23. In 2023, non-concessional loans exceeded concessional ones for the first time, the report notes.
The “increasing proportion” of non-concessional finance raises “long-term affordability and equity” concerns, the authors warn. They also point to the risk of an “adaptation investment trap” – whereby rising climate disasters increase developing countries’ “indebtedness”, which subsequently makes it harder for them to invest in adaptation.
The report also finds that loans and other forms of “debt instruments” comprised “58% on average” of international adaptation finance in 2022-23.
The NCQG text highlights the need for “concessional” and “non-debt creating” finance.
(This came after strong calls from many developing countries to exclude “non-concessional” loans – which result in wealth flowing back to the donor countries as loan repayments and interest – as a form of climate finance. Analysis has shown that many developing countries are spending more on servicing debts than they receive in climate finance.)
Elsewhere, the authors also find that funding for new adaptation projects through UN Framework Convention on Climate Change (UNFCCC) funds (the adaptation fund, green climate fund (GCF) and the least developed countries fund (LDCF) and special climate change fund (SCCF) managed by the Global Environment Facility) saw a “large spike” in 2024, with grants reaching around $920m.
However, they note that the recent increase “may not be a trend, with financial constraints likely to rise beyond 2025”.
Developing nations’ adaptation finance needs are 12 times greater than current flows
While previous UN adaptation gap reports have investigated adaptation finance shortfalls through to 2030, this latest analysis extends its estimates through to 2035.
This is in light of the NCQG, which states that developed countries should “take the lead” in raising “at least $300bn” a year for climate action in developing countries by 2035.
The report calculates that the costs of adaptation by 2035 for developing countries sit in a “plausible central range” of $310-365bn annually. It explains that it has arrived at this range based on “two lines of evidence”:
- A modelled estimate of the additional costs of adaptation, calculated using “global sectoral models with national-level resolution”. This exercise pins the cost of adaptation for developing countries at $310bn a year by 2035 under an intermediate emissions scenario.
- An analysis of the climate finance needs set out by developing countries in 97 national adaptation plans and nationally determined contributions (NDCs) submitted to the UNFCCC – with “extrapolation” of this data to all 155 developing countries. This results in the upper figure of $365bn per year up to 2035.
The chart below shows the disparity between existing finance flows (dark blue bar) and adaptation finance needs and modelled costs (red bars).
With current levels of international adaptation finance estimated at $26bn a year, the report calculates that developing countries are facing an “adaptation finance gap” in the range of $284-339bn per year by 2035.
As such, it calculates that the adaptation finance needs of developing countries by 2035 are “12-14 times” as much as current finance flows.
Of the public adaptation finance that has been issued, a higher proportion currently goes to the countries most exposed to climate hazards, according to the report. It notes that, in 2022-23, $10.4bn and $1.2bn was allocated to least-developed countries (LDCs), including Afghanistan and Rwanda, and small island developing states (SIDS), such as Tuvalua and the Marshall Islands, respectively.
Nevertheless, finance provided to these climate-vulnerable nations is still “modest relative to needs”, the report warns. It estimates that the adaptation finance needs of LDCs and SIDS are $50bn a year.
It also finds that per-capita adaptation finance to both country groups was lower in 2022-23 than previous years, at $9 for LDCs and $20 in SIDs.
A majority of countries have a national adaptation plan or strategy in place
Under the framework for the global goal on adaptation agreed at COP28, countries said they would put in place “national adaptation plans, policy instruments and planning processes and/or strategies” by 2030.
To assess the “global status” of national adaptation planning, the authors of the report tracked the publication of national plans, strategies and policies for adaptation in each country.
According to the report, the first national adaptation policy was published in 2002. It finds that there was a “notable acceleration” in countries developing national adaptation planning instruments over 2011-21, but says that, since then, progress has “slowed significantly”.
According to the report, 87% of countries had at least one national adaptation policy, strategy or plan in place as of 31 August 2025. However, 36 of these 172 countries’ plans are “expired” or “outdated”.
Meanwhile, 25 countries had no national adaptation plan at all, according to the report. It explains that these are “predominantly developing countries, suggesting that financial, technical and human resource constraints inhibit national adaptation planning”.
Of these countries without plans, 21 have “initiated a process to develop” a national adaptation plan, according to the report. However, it notes that many of these countries have “been in this process for a long time”.
The chart below shows the percentage of countries from different “country classifications” that have no national adaptation planning instrument in place (red), an expired adaptation planning instrument in place (yellow) and a valid instrument in place (green).
The report also discusses different types of adaptation “mainstreaming”. This is defined by the report authors as the “integration of adaptation objectives and climate risk considerations into the established functions, policy and practice of government institutions to build climate resilience”.
The authors list six different mainstreaming strategies. For example, “directed” mainstreaming means “dedicating funding, staff capacity-building and resources specifically to adaptation, including through financial frameworks and fiscal processes such as budget planning”.
Another example is “regulatory mainstreaming”, which means “modifying the formal or informal policy instruments such as legislation, frameworks, strategies and plans by integrating adaptation”.
According to the report, only regulatory mainstreaming is captured by the framework for the global goal on adaptation’s target related to planning.
The report also outlines the different “levels” of mainstreaming. These range from “prioritisation”, which it describes as a strong level of mainstreaming in which adaptation takes precedence over existing policy goals, to “coordination”, in which adaptation “is recognised as a policy goal, but is secondary to existing priorities”.
However, the report says there is “presently no agreement on how to measure and assess the outcomes of mainstreaming”.
Implementation of adaptation measures is progressing – but gaps remain
Under the UN “enhanced transparency framework”, countries are required to submit information about their climate progress in biennial transparency reports (BTR). The first report was due at the end of 2024.
The adaptation gap report calls BTRs the “most comprehensive national source of information on adaptation implementation worldwide available”.
The report says that 105 countries had submitted BRTs as of 31 August 2025, of which 94 include details about adaptation
The authors find that 75 of these BTRs mention gender in relation to adaptation. However, only 4% of the results reported through BTRs are directly related to “gender and social inclusion”.
The report also highlights the “uneven coverage” of BTRs globally. According to the report, 88% of developed countries have submitted a BTR, compared to only 37% of developing countries.
It adds that there are further inequalities within the bracket of “developing countries”. Only 21% of SIDS and 14% of LDCs have submitted BTRs with “detailed information on climate impacts and adaptation”, according to the report.
This could “indicate that preparing national reports such as BTRs is most burdensome for the countries with the least capacity”, the report authors suggest.
The map below shows the countries that have submitted a BTR including “detailed information on climate impacts and adaptation” (blue) and those that have not (grey). For the former category, darker blue indicates that the country’s BTR includes more segments of text (data points) about climate impacts and adaptation.
The report finds that countries are “disproportionately reporting on climate hazards, systems at risk, climate change impacts and adaptation priorities” in BTRs. Meanwhile, only 15% and 7% of the data points in the map above discuss adaptation “actions” and “results” respectively.
In total, the report identifies 1,640 “adaptation actions” across 68 BTRs. It says that 23% of these are related to “biodiversity and ecosystems”, 18% to “infrastructure and human settlements”, 16% to “water and sanitation” and 14% to “food and agriculture”.
However, it finds that actions targeting health and poverty alleviation or livelihoods are each accounting for only 5%, while those addressing cultural heritage are “nearly absent” and account for less than 1% of all reported actions.
In a separate analysis, the report explores documents submitted by developing countries to the UNFCCC to understand how adaptation needs break down by sector. It finds that the 55 plans submitted by developing countries which include “detailed sectoral information” reveal that the agriculture and food sector and water supply are “common priorities across all regions, though they vary in terms of their relative importance”.
The NCQG is insufficient on its own to meet adaptation finance needs
At COP29 last year, developed nations pledged to raise at least $300bn per year under the NCQG for both mitigation and adaptation.
The report says that, although the target “appears significantly higher than the previous goal for developed countries to mobilise $100bn by 2020 for developing countries”, it is still “clearly insufficient” to meet adaptation finance needs in 2035.
The report sets out two reasons for this.
First, the authors explain that the $300bn target is not adjusted for inflation. It says that adaptation costs for developing countries are currently estimated at $310-365bn annually until 2035, based on costs in 2023. However, when adjusting for an inflation rate of 3% per year for the next decade, this number rises to US$440–520bn by 2035.
(In an analysis published last year, Carbon Brief noted that the $300bn target does not account for inflation.)
The plot below shows the effect of inflation on adaptation finance needs (dark blue) and modelled costs (light blue). It also shows the NCQG goal, accounting for inflation, based on 2023 costs (red) and without inflation based on 2035 costs (pink). It also shows the NCQG goal of $300bn by 2035 (yellow).
Second, it notes that the NCQG covers both mitigation – namely, efforts to cut emissions – and adaptation. So far, it warns that no “subgoal” has been agreed to determine how much money goes to each.
The report authors have also developed two scenarios exploring how much the NCQG would bridge the adaptation finance gap, if the $300bn target is met, both of which account for inflation. These are:
- A “minimum adaptation scenario”. The authors assume that 26% of the NCQG money will be used for adaptation finance as this is the percentage of all international climate finance that was spent on adaptation over 2011-20. Based on historical proportioning of finance, $3bn of the resulting $78bn this would go to SIDS and the rest to $25bn to LDCs.
- A “maximum adaptation scenario”. Under this scenario, the Glasgow Pact and Baku to Belém Roadmap are achieved, meaning that adaptation funding reaches $40bn annually by 2025 and $120bn annually by 2030. They also assume that adaptation finance grows by 7% per year, reaching $166bn by 2035 – more than half of the NCGQ finance goal of $300bn. Under this scenario, SIDS would receive $6bn in adaptation funding by 2035 and LDCs would receive $55bn.
The report concludes that, even if the NCQG is achieved, a “significant adaptation finance gap” is likely to remain in 2035 “regardless of the share of international public climate finance that will flow towards adaptation”.
Meanwhile, the report notes that private-sector finance can help “fill the adaptation finance gap” – but cautions that its overall contribution is likely to be “modest”.
The “realistic” potential for private-sector investment, according to the report, is $50bn per year by 2035 – a figure it estimates would cover 15-20% of overall estimated needs.
Reaching this level of private-sector finance will require “targeted policy action” given that current private-sector flows to “publicly identified” adaptation priorities in 2023 are estimated at $5bn, it notes.
Furthermore, UNEP warns that many proposed approaches for raising private-sector funds for adaptation measures pass “most of the costs of adaptation back to developing countries or households”.
The post UN report: Five charts which explain the ‘gap’ in finance for climate adaptation appeared first on Carbon Brief.
UN report: Five charts which explain the ‘gap’ in finance for climate adaptation
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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Pacific leaders will launch the first call for proposals next week for a new regional fund designed to swiftly channel climate finance to local communities
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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Guest post: Why tough methane cuts are crucial for keeping warming ‘well-below’ 2C
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