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Nearly a tenth of global climate finance could be under threat as US president Donald Trump’s aid cuts risk wiping out huge swathes of spending overseas, according to Carbon Brief analysis.

Last year, the US announced that it had increased its climate aid for developing countries roughly seven-fold over the course of Joe Biden’s presidency, reaching $11bn per year.

This likely amounts to more than 8% of all international climate finance in 2024.

However, any progress in US climate finance has been thrown into disarray by the new administration.

Trump has halted US foreign aid and threatened to cancel virtually all US Agency for International Development (USAid) projects, with climate funds identified as a prime target.

USAid has provided around a third of US climate finance in recent years, reaching nearly $3bn in 2023, according to Carbon Brief analysis.

Another $4bn of US funding for the UN Green Climate Fund (GCF) has also been cancelled by the president’s administration.

One expert tells Carbon Brief that more climate funds will likely end up on the “cutting block”.

Another warns of an “enormous gulf” to meeting the new global $300bn climate-finance goal nations agreed last year, if the US stops reporting – let alone providing – any official climate finance.

Carbon Brief’s analysis draws together available data to explain how the Trump administration’s cuts endanger global efforts to help developing countries tackle climate change.

How much did climate finance increase under Biden?

The US is by far the world’s largest economy and biggest historical emitter of carbon dioxide (CO2).

This means that, while it is the fourth-biggest national provider of international climate finance, its overall share is low relative to the nation’s wealth and responsibility for climate change. As a result, the US has long been seen as a laggard in this area.

The US provides 0.24% of its gross national income (GNI) as aid for developing countries, which includes some climate funding. This is the same share as the Czech Republic, a nation with a per-capita GNI three times smaller.

US climate-finance contributions stalled during Trump’s first four-year term as president, when other developed countries were ramping up to meet their target of providing and mobilising $100bn a year for developing countries by 2020.

A shift in focus came when Biden became president in 2021. He established an international climate finance plan to scale up US efforts, in line with US obligations under the Paris Agreement.

Biden also announced that the US would reach $11.4bn in annual climate finance by 2024.

This goal was achieved, according to “preliminary estimates” announced by the US during the COP29 climate summit at the end of 2024. These estimates, which are unlikely to be confirmed by the new administration, are shown in the chart below.

Climate finance flatlined during Trump's first presidency, but increased rapidly under the Biden administration
US climate-finance contributions to developing countries, 2015-2024, with Democrat presidencies indicated by blue columns and Trump’s Republican presidency indicated by red columns. Figures for 2015-2022 are based on official figures reported to the UN in biennial reports (BRs) and, for the years 2021 and 2022, the biennial transparency report (BTR). Figures for 2023 and 2024 have only been announced by the Biden administration in media releases, without the underlying data. All years only include bilateral funds and contributions to multilateral funds, not shares of multilateral development bank finance or private finance. Source: BRs, BTR, US Department of State.

The figures are based predominantly on “bilateral” climate finance reported to the UN. They also include US finance distributed via multilateral climate funds, such as the Global Environment Facility (GEF) and the GCF.

Bilateral climate finance largely comes from aid programmes with climate benefits, such as supporting a geothermal project in the Philippines, investing in “climate-smart” agriculture in Bangladesh, or improving water security in Niger.

The US significantly increased its contribution towards climate finance during the Biden administration. Ramping up relevant US aid projects and multilateral funding helped developed countries to hit the $100bn climate-finance target – albeit two years late in 2022.

The $11bn reported by the US in 2024 would be the equivalent of 21% of all bilateral and multilateral climate fund inputs that year – up from around 4% under the previous Trump presidency. These funds are shown by the blue bars in the figure below.

(Estimates for 2023 and 2024 assume a steady rise in climate finance from sources beyond the US, as official figures beyond then have not been released. See Methodology for more information.)

Even when considering other sources of international climate finance – specifically multilateral development banks (MDBs) and “mobilised” private finance shown in grey in the figure below – the US has contributed a sizable share in recent years.

After lingering around 2% during the last Trump administration, the US share of total climate finance roughly quadrupled to more than 8% in 2024, Carbon Brief analysis suggests.

Around 8% of all international climate finance was provided directly by the US in 2024
International climate finance provided and mobilised by developed countries, 2015-2024. US figures for 2023 and 2024 were announced by the Biden administration in media releases. Other figures for 2023 and 2024 are extrapolations, based on existing pledges and planned reforms to financial architecture expected by 2030. Private finance is missing from the 2015 OECD data. Export credit data is included in the bilateral totals. Source: BRs, BTR, US Department of State, OECD, NRDC.

It is also worth noting that the US, as the biggest shareholder at the World Bank and a major shareholder at other MDBs, can be linked to a large portion of their finance. This contribution is not factored into official US reporting, so it has not been included in this analysis.

Even accounting for MDB contributions, US climate finance spending is still far lower than its “fair share”, based on its historical responsibility for climate change and ability to pay. Some analysts have put the US fair share as high as 40-50% of climate finance overall.

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What are the climate impacts of cutting USAid?

Upon taking office for the second time in January 2025, Trump immediately took aim at international aid spending and climate action with a flurry of executive orders.

One order announced plans to withdraw the US from the Paris Agreement and criticised such treaties for “steer[ing] American taxpayer dollars to countries that do not require, or merit, financial assistance”. It also “revoked and rescinded” Biden’s international climate finance plan.

In another executive order, Trump announced a “pause” on US foreign aid “for assessment of programmatic efficiencies and consistency with US foreign policy”.

USAid handles 60% of US foreign aid – more than $43bn in 2023 – while the State Department oversees most of the remainder. Trump says he wants to “close [USAid] down” and his advisor Elon Musk has called it a “criminal organisation”.

Donald Trump post on Truth Social: "USAID IS DRIVING THE RADICAL LEFT CRAZY, AND THERE IS NOTHING THEY CAN DO ABOUT IT BECAUSE THE WAY IN WHICH THE MONEY HAS BEEN SPENT, SO MUCH OF IT FRAUDULENTLY, IS TOTALLY UNEXPLAINABLE. THE CORRUPTION IS AT LEVELS RARELY SEEN BEFORE. CLOSE IT DOWN!"

Source: Truth Social.

Trump requires the approval of Congress to repurpose USAid funds or, indeed, abolish the agency. His administration’s actions have, therefore, been described as “illegal” and “unconstitutional” by senior Democrats and aid workers.

Yet, despite lawsuits and court orders instructing the administration to lift the pause, it has since stated its intention to eliminate more than 90% of USAid contracts and, more widely, $60bn of US foreign aid.

This would have major implications for US climate finance.

News outlets have reported on the climate-related programmes at risk, sometimes stating that USAid has funded half a billion dollars of climate programmes annually in recent years.

This figure, while based on USAid’s own reporting of its clean energy, climate adaptation and nature projects, is a significant underestimate of its total climate-finance contributions.

Carbon Brief analysis suggests that USAid contributed $2.8bn of climate finance in 2023, the latest year for which data is available. Other US departments with aid contributions in the OECD database contributed smaller sums, bringing total climate spending up to $2.9bn.

This equates to around a third of US climate finance that year. If a similar share from these departments was counted as climate finance in 2024, it would amount to nearly $4bn, Carbon Brief finds.

(These are estimates based on “climate-related” aid data reported to the OECD. See Methodology for more details.)

A large chunk of US climate finance comes from USAID
Approximate amount of US climate finance in 2022 and 2023 that was overseen by USAid and a small number of other departments distributing aid (dark blue), or from other sources (lighter blue/grey). Data for the breakdown of bilateral and multilateral finance is not available for 2023. Source: OECD CRS, BRs, BTR, US Department of State

Climate-finance experts tell Carbon Brief that these higher figures align with the fact that many aid projects targeting other issues, such as agriculture, have climate components.

Dr Ed Carr, a centre director at Stockholm Environment Institute US who has previously worked at USAid, tells Carbon Brief:

“The way that the Biden administration was doing stuff and the way that [former president Barack] Obama before was doing stuff, [was to] start to weave a degree of climate sensitivity into everything…So, basically, a huge percentage of programmes [are] working on some aspect of climate.”

Unlike many forms of climate finance, USAid projects include lots of grant-based funding, which many developing countries view as preferable to loans and better suited to supporting climate adaptation.
Relevant projects backed by USAid in recent years include support for a food-security programme in Ethiopia, upgrading a dam in Pakistan and protecting water supplies in Peru.

The Trump administration has made it clear that “climate” is one of the issues that it is scrutinising as it assesses aid projects for consistency with what it defines as US interests. A survey sent to grant recipients several weeks after the initial executive order asks:

“Can you confirm this is not a climate or ‘environmental justice’ project or include such elements?”

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Are other sources of climate finance at risk?

The remaining billions in climate finance are handled by more than a dozen organisations, distributing grants, loans, development finance and export credits.

Around $1.2bn of US climate finance in 2022 was paid into international funds, including the GEF. This amounts to a fifth of the total US climate finance that year.

The Biden administration did not release a breakdown of how much money went to these funds in 2023 and 2024. However, in 2023 the country paid out $1bn for the GCF alone.

Such funding is also at risk as the new administration pulls away from what the White House calls “international agreements and initiatives that do not reflect our country’s values”. Notably, the US has now cancelled $4bn in funds previously committed to the GCF.

(Biden and Obama pledged $3bn each to the fund. However, neither of them ever delivered more than $1bn of their pledge, leaving $4bn outstanding.)

As the chart below shows, this means the US contribution to the GCF is now lower than that of Sweden – a country with an economy 50 times smaller.

Following Trump's cuts, the US has now pledged less to the Green Climate Fund than Sweden
Total pledges to the Green Climate Fund from the biggest contributors, covering the three replenishment periods of 2014, 2019 and 2023. Outstanding US pledges that have now been cancelled are indicated by the hatched area in the red column. Source: NRDC GCF tracker.

The GCF is not the only specific fund that has been targeted. The US formally ended its involvement in the UN loss and damage fund, which it pledged $17.6m towards in 2023. It has also withdrawn from the Just Energy Transition Partnership initiative, which included at least $56m in grants to help South Africa transition away from coal power.

Another Trump executive order announced a review of “international intergovernmental organisation” membership, including MDBs.

There is an assumption that the US will not give up its considerable power in these banks. However, Trump supporters, including those behind the influential Project 2025, have laid out plans for withdrawing the US from the World Bank.

A large chunk of the remaining US climate finance in recent years has come from the US International Development Finance Corporation (DFC), which committed more than $3.7bn in climate finance in 2024 and a similar amount in 2023. This included loans for a wind power project in Mozambique and a railway to carry critical minerals through Angola.

DFC is a development finance institution that invests in private enterprises and was set up under the first Trump administration. It has so far been insulated from US aid cuts and there has been speculation that it may now play a larger role in US foreign policy.

Leaning more heavily on DFC, as well as the US Export-Import Bank (EXIM), would not be suitable for climate finance, Ritu Bharadwaj, a climate-finance principal researcher at the International Institute for Environment and Development (IIED), tells Carbon Brief:

“If these mechanisms remain intact while grant-based finance is gutted, it signals a shift away from public, needs-based funding toward finance that prioritises US commercial and strategic interests. In other words, what little climate finance remains will likely benefit US corporations first, rather than frontline communities.”

Additionally, even if such organisations are favoured by the new administration, this does not mean their climate projects will be protected. Benjamin Black, Trump’s nominee to lead DFC, wrote a blog post about the corporation in January, stating:

“The Biden administration’s emphasis on virtue-signaling – such as dedicating 40% of [DFC’s] recent commitments to green projects – raises serious concerns.”

Carr tells Carbon Brief that more US climate spending could still end up on the “cutting block”:

“From what we’ve seen so far, it looks to me like they are going to try and root out everything that they see as clearly related to climate.”

He caveats this by noting that some of the money the Biden administration would have counted as climate finance may continue, but not be defined as such.

This highlights the importance of accounting when assessing climate finance. Different governments around the world report different things as climate finance, depending on their priorities and political leanings.

For example, during the last Trump presidency, the US stopped reporting on climate finance to the UN. When calculating progress towards the $100bn goal during this period, the OECD had to estimate US figures based on “provisional data” or averages from previous years.

The Biden administration retrospectively reported the missing data from the Trump years in 2021, resulting in the OECD scaling down a previous estimate.

Clemence Landers, a senior policy fellow at the Center for Global Development (CGD) who previously worked at the US Treasury, tells Carbon Brief that a “very educated guess [is] that there will be no reporting from the US” in the coming years.

The US government website tracking aid has not been updated since December.

If climate finance is not recorded, this could hamper its inclusion in the annual $100bn goal, which lasts until 2025, as well as the $300bn goal that countries agreed on last year at COP29 to replace it, as Landers notes:

“That does leave an enormous gulf in terms of the new global climate-finance target.”

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Methodology

Climate-finance reporting practices mean that official data can be difficult to analyse in detail.

In this article, annual US climate-finance figures for the period 2015-2022 are based on those reported by the US government to the UN in biennial reports (BRs) and, for the years 2021 and 2022, its first biennial transparency report (BTR).

These can be considered “official” climate-finance figures. They align with the figures that the US federal government has released and are the ones used to inform the OECD’s assessments of developed countries’ progress towards the $100bn annual target.

The figures only include bilateral climate finance and inputs into multilateral climate funds. MDB shares and private finance mobilised are not covered. Again, this aligns with the “climate-finance” totals quoted in progress reports by the Biden administration.

The climate-finance totals for 2023 and 2024 are based on releases from the US Department of State during the Biden administration. These figures are for the US financial year (FY), which runs from 1 October to 30 September. However, the FY figures are the same as the calendar year numbers reported to the UN for 2021 and 2022, so Carbon Brief assumes the same is true for 2023 and 2024.

Due to the significant time lag in official reporting to the UN, the figures underpinning these totals are not due to be released until 2026. (The previous Trump administration did not report them at all and it is unlikely that the current one will either, now that the US has announced its departure from the Paris Agreement.)

Given this time lag, estimates for total international climate finance in 2023 and 2024 are derived from a joint analysis by the thinktanks Natural Resources Defense Council (NRDC), ODI, Germanwatch and ECCO. This calculated likely totals in 2030, based on existing pledges and planned reforms. Carbon Brief assumes a steady trajectory to the overall $197bn estimated under the thinktanks’ “business-as-usual” scenario, with bilateral finance, specifically, reaching $50bn by 2025.

Climate-finance figures reported to the UN by the US do not include details of the government departments and agencies responsible, making it difficult to determine the share overseen by USAid. The Biden administration also did not report the breakdown between agencies.

This data is reported to the OECD Creditor Reporting System (CRS), which contains figures up to 2023. However, the information in the CRS is not “official” climate finance, but rather “climate-related development finance”, identified as such using Rio Markers. Most countries apply simple coefficients to convert the figures they report to the CRS into their climate-finance submissions to the UN, but the US calculates its climate-finance submissions separately.

Nevertheless, to obtain approximate figures, Carbon Brief has assumed that 100% of CRS projects marked as “principal” climate projects and 50% of the projects marked as “significant”, are climate finance. This aligns with a methodology used by other organisations, such as Oxfam, as well as other nations, including Germany, Japan and Denmark.

However, it is only a rough estimate. Experts that Carbon Brief consulted stressed the uncertainties of climate finance reporting and said the numbers could be higher or lower.

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Analysis: Nearly a tenth of global climate finance threatened by Trump aid cuts

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Climate Change

From firefighting to future-proofing: Preventing wildfires must be the priority

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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.

    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.

    A burnt olive tree in an area affected by a wildfire in Ano Sichaina near Patras, Greece, August 14, 2025. REUTERS/Louiza Vradi

    A burnt olive tree in an area affected by a wildfire in Ano Sichaina near Patras, Greece, August 14, 2025. REUTERS/Louiza Vradi

    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.

    A drone view shows burnt cars following a wildfire in Dymi, near Patras, Greece August 14, 2025. REUTERS/Louiza Vradi

    A drone view shows burnt cars following a wildfire in Dymi, near Patras, Greece August 14, 2025. REUTERS/Louiza Vradi

    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.

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    Climate Change

    Guest post: Why tough methane cuts are crucial for keeping warming ‘well-below’ 2C

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    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.

    Peak global warming relative to 1850-1900 reached until 2100 (50% likelihood), for combinations of the year of global net-zero CO2 emissions (x-axis) and the change in global methane (CH4) emissions between 2020 and that year (y-axis), assuming linear trajectories. Black lines are contours of equal peak warming. The three bars on the right show independent estimates of where CH4 emissions could or would land on the same vertical scale: CH4 mitigation available at no net cost (IEA, red), the 2030 mitigation potential (Global methane status report, orange), and the current legislation scenario for 2050 (Global methane status report, purple). Adapted from Weber et al. (2026).

    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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    Climate Change

    Pacific Islands Forum leaders, Albanese must not lose focus on Pacific priorities of climate and ocean

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    KOROR, PALAU, Monday 31 August 2026 — As Pacific leaders gather for the 55th Pacific Islands Forum Leaders Meeting in Palau from today, Greenpeace Australia Pacific is urging Prime Minister Anthony Albanese to stand with Pacific family by keeping Pacific needs at the heart of negotiations, backing longstanding Pacific leadership, supporting Pacific energy sovereignty and ocean custodianship, and holding the line on 1.5°C.

    Against the backdrop of tense geopolitical turmoil, increasingly frequent and lethal extreme weather disasters, the threat of deep sea mining and an energy crisis driven by fossil fuel dependence, the Pacific Islands Forum Leaders Meeting (PIFLM) is a critical moment for Pacific nations to unite with Pacific needs central to regional dialogue.

    The climate crisis, security, the opportunities of renewable energy in the Pacific, ocean protection, and the shifting political landscape will be the focus of the Forum’s discussions.

    Speaking from Palau, Shiva Gounden, Head of Pacific at Greenpeace Australia Pacific, said:
    “The Pacific Islands Forum is the most important multilateral forum in our region, unifying the Pacific under increasingly turbulent global circumstances. We are urging Forum members, including Australia, to not lose focus of Pacific priorities of climate and oceans amid noise and external pressures at this year’s meeting.

    “It is very clear that the greatest security threat to our region is climate change and the only way we can address that is through a just transition away from fossil fuels. Regional cooperation is an antidote to climate chaos and geopolitical tension – together, our region can be guided by Pacific nations’ legacy of leadership from the frontlines of the climate crisis, as we build a more peaceful and secure world.

    “This year’s Forum will set the stage as we build momentum toward COP31 and a Fossil Fuel Free Pacific. Australia must back Pacific energy sovereignty as a solution to the compounding threats facing our region, including soaring costs of living and increasingly lethal extreme weather disasters, and resist the militarisation of our oceans, deep sea mining, and power politics.

    “We must not lose sight of what is needed. The regional adoption of Pacific-led solutions, a Pacific pre-COP with focus on advancing the just transition away from fossil fuels and community-targeted finance for strong and resilient futures beyond fossil fuels must be the foundations of this year’s Forum discussion. What we need now is stronger political will.”

    Also in Palau, Dr Simon Bradshaw, COP31 Lead and climate expert at Greenpeace Australia Pacific, said:
    “Prime Minister Albanese faces a major test of Australia’s climate credibility and Pacific partnership this week. We cannot be a friend to the Pacific and continue to expand fossil fuel production. The best way for Australia to remain the Pacific’s security partner of choice is to act faster on the Pacific’s number one security concern — climate change.

    “The Albanese Government has approved at least five new coal and gas projects since the last Pacific Islands Forum Leaders Meeting, and 36 since being elected, every one of which increases the threats to life, security and sovereignty facing Pacific communities.

    “Nowhere in the world are the dangers of fossil fuels or the benefits of renewable energy clearer than in the Pacific, which faces the double blow of climate disasters and expensive fuel imports.

    “Australia, as incoming President of Negotiations for COP31, has a responsibility to follow the Pacific’s lead, embrace the vision of a resilient Fossil Fuel Free Pacific, and do everything possible to keep 1.5°C alive. Doing so would establish Australia as a highly effective middle power, a force for good in troubled times, and a true ally and partner to the Pacific.”

    —ENDS—

    Greenpeace Australia Pacific has delegates from the Pacific and Australia at the PIFLM in Palau available for interview

    Pacific Islands Forum leaders, Albanese must not lose focus on Pacific priorities of climate and ocean

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