Welcome to Carbon Brief’s DeBriefed.
An essential guide to the week’s key developments relating to climate change.
This week
Three years to 1.5C
‘DOOMED TO BREACH’: At current carbon dioxide (CO2) emission levels, the world is “doomed to breach the symbolic 1.5C warming limit” in as little as three years, according to research by 60 climate scientists covered by BBC News. (Carbon Brief carried a guest post by two scientists involved in the study.) Co-author and Carbon Brief climate science contributor Dr Zeke Hausfather told the Washington Post: “Some reports, there’s a silver lining. I don’t think there really is one in this one.”
FLOODED AFRICA: South Africa declared a national disaster after floods killed more than 90 people in four of the country’s nine provinces, Bloomberg reported. This is the “second time in about seven months” that the government has invoked the measure to “free up funds for relief and reconstruction”, it added. Separately, 29 people were confirmed to have died “after heavy rains at the weekend triggered floods and landslides” in Kinshasa, the capital of the Democratic Republic of the Congo, the Associated Press reported.
CHINA DELUGE: Heavy rainfall fuelled by Typhoon Wutip has caused the “worst flood in a century” in China’s southern province of Guangdong, with the Sui river in the Huaiji county swelling to “over five metres above the official danger level…the highest on record”, reported state broadcaster CGTN. Local authorities have declared a “top-level emergency” as economic losses from the floods are estimated at $5.7m, the outlet added.
HURRICANE AND HEAT DOME: In North America, forecasters have warned that parts of the US could see “dangerously high temperatures and extreme humidity” from an incoming heat dome, the Wall Street Journal reported. The Associated Press reported that a “fast-moving brush fire” burned hundreds of acres and forced the evacuation of 50 Maui residents in Hawaii, even as 2023 wildfire survivors struggle with declining health, per the Guardian. Hurricane Erick made landfall on Mexico’s Pacific coast on Thursday “shortly after being downgraded slightly from an ‘extremely dangerous’ category 4” storm, noted BBC News.
Bonn talks turn ‘bitter’
BEGIN AGAIN: The Bonn climate talks – the annual two-week preparatory talks held each June deemed “critical to thrash out differences” before each year’s COP – began on Monday “amid severe geopolitical turmoil and renewed tensions”, the Hindustan Times reported. It added that the meetings are shrouded by a “shadow of failed climate-finance talks” at COP29 in Baku, Azerbaijan last year and “divergent views” on a roadmap to raise climate finance to $1.3tn.
AGENDA FIGHT: The start of the talks was delayed by an “agenda row”, after Bolivia – on behalf of the Like-Minded Group of Developing Countries (LMDC) – sought to include items on climate finance from developed nations and “climate change-related trade-restrictive unilateral measures”, Climate Home News reported. Donald Trump’s administration “decided…not to send a delegation to the preparatory meetings” – meaning the US was absent in Bonn for the first time ever, it added.
‘BITTER EXCHANGES’: After 30 hours of “bitter exchanges”, the agenda was adopted on Tuesday “to polite applause and a bigger sense of discontent”, another Climate Home News article said. The Bonn chairs agreed to hold “substantive consultations” on climate finance and report back in Belém at COP30, it continued. Negotiators can now “turn their full attention to equally thorny discussions” on climate adaptation indicators and fossil fuels, it added. (Carbon Brief’s Josh Gabbatiss and Molly Lempriere will report live from Bonn next week.)
Around the world
- BRUSSELS BAN: The European Commission tabled a bill that, according to Euractiv, “would phase out the large volumes of Russian gas still flowing into the EU until the end of 2027”, adding that the ban would stand “irrespective of whether there is peace” in Ukraine.
- UK-CHINA MEET: UK officials including energy secretary Ed Miliband, climate envoy Rachel Kyte and nature envoy Ruth Davies sat down with Chinese counterparts, including the head of China’s Ministry of Economy and Environment, in London this week to discuss the “next steps of climate cooperation”, according to Chinese business publication Jiemian News.
- AMAZON OIL BID: Brazil’s national oil agency has “auctioned off” several oil sites near the mouth of the Amazon river and two inland sites near Indigenous territories months before the country is due to host COP30, the Associated Press reported.
- BLACKOUT BLACK BOX: Spain announced the findings of a 49-day probe into the “catastrophic” Iberian blackout, the Financial Times reported, “spread[ing] the blame…between its grid operator and electricity companies”. (See Carbon Brief’s updated Q&A.)
- MISINFORMATION MEASURED: A review of 300 studies found that action on climate change is being “obstructed and delayed by false and misleading information stemming from fossil-fuel companies, rightwing politicians and some nation states”, the Guardian said.
- OIL PEAK EARLY: According to the International Energy Agency (IEA), China’s oil demand will peak in 2027, two years earlier than previously forecast, Bloomberg reported. At the same time, India’s “thirst for oil will rise more than any other country” over the next five years, wrote the Times of India.
120 kcal
The amount of calories the average person could lose per day for every 1C of warming, due to climate change’s impact on six key crops, according to research covered by Carbon Brief.
Latest climate research
- New forests larger than the size of North America would need to be planted to offset the potential CO2 emissions from fossil fuel reserves held by the world’s top 200 fossil fuel companies, found new analysis in Communications Earth & Environment.
- According to new research in Science Advances, human-driven climate change will remove coral habitat faster than corals can expand into higher-latitude, cooler waters. It found that severe coral cover declines will likely occur over the next 40-80 years, while large-scale expansion “requires centuries”.
- New rapid analysis by World Weather Attribution estimated that climate change will make Saturday’s “widespread heat” of 32C in southeast England “about 100 times” more likely.
(For more, see Carbon Brief’s in-depth daily summaries of the top climate news stories on Monday, Tuesday, Wednesday, Thursday and Friday.)
Captured

Carbon Brief charted eight decades of the UK’s nuclear energy fleet – from setting up the world’s first commercial reactor in Cumbria in 1956 to UK chancellor Rachel Reeves greenlighting the Sizewell C reactor last week. The chart shows the contribution of each of the UK’s nuclear plants to the country’s overall capacity, according to when they started and stopped operating. It also shows timelines for new planned nuclear capacity yet to come on board, plus known planned closure dates.
Spotlight
Forecasting Mumbai’s fierce monsoon
This week, Carbon Brief visits Mumbai’s official monsoon monitoring centre and “war room” to examine how the city is responding to its earliest downpour on record.
If extreme weather had a poster-child capital, it would be Mumbai. The megacity has it all – catastrophic urban flooding every monsoon, sea level rise, landslides, climate-change induced tropical cyclones, heatwaves across all its seven islands – and, with further climate change, it will only get worse.
Famed for its “spirit”, Mumbai’s 26 million metropolis dwellers have come to loathe the term that valorises their resilience every monsoon, evident from the memes that flooded the internet on 26 May when the monsoon arrived earlier than ever before in the city’s history.
On its first monsoon day of the year, the city received 135.4mm of rainfall rather than its normal of 0.2mm – an excess of 67,600%. Visuals of a flooded metro line that opened only 17 days ago went viral.
Faced with criticism, the state’s deputy chief minister Eknath Shinde equated the rains to a “cloudburst” and admitted that the country’s richest civic body – that he heads in the absence of elected representatives – was caught off-guard this year.
Despite having a year to prepare, Shinde admitted that pumps meant to remove water from a city that is barely above sea level were not working to full capacity. They stand in sharp contrast to the billion-dollar highways that have robbed the city of its natural flood defences and now dominate its skyline and waterfront, but are already being overwhelmed by extreme weather.
In India’s financial capital – where 73% of all offices and commercial establishments are within 500m of a flood hotspot and 69% of all employees experience “hindered access” from waterlogging trying to get to or leave work – forecasting the monsoon is fraught, essential and getting trickier with climate change.
Forecasting the monsoon
Dr Sushma Nair, a meteorologist with the India Meteorological Department’s (IMD) regional monitoring centre, has the unenviable job of getting it right.
Nair and her team work out of the Colaba Observatory, at the southernmost tip of the city. Established in 1826 by the East India Company, it is one of world’s longest-running observatories and is older than the IMD itself – as well as many parts of the city that have been reclaimed from the sea.
“As weather-in-charge, it’s a 24/7 job,” Nair told Carbon Brief during a visit to the observatory.
Nair’s day begins at 8:30am, when her team prepares a forecast, checks upper air observations, runs models and decides what colour – yellow, orange or red – to assign the region for the next 24 hours, before hopping on a video call with her regional contemporaries and the IMD HQ.
“No journalist will get a forecast from us before 11:30 or 12:30, because we are discussing the weather,” she said.

Meteorological Centre has a Nowcast that refreshes every three hours, allowing forecasters to account for sudden changes in the weather and upgrade the city to a red alert, based on satellite and radar warnings.
Nair confesses that she “normally” checks the Nowcast at 4am, “because I lose my sleep at 3am”, and has the city’s chief disaster manager on speed dial for a red nowcast, no matter what the hour. “I am an insomniac, so don’t take that as a regular forecaster’s sleep hours,” she joked.
Her biggest source of dread is two-hour intense downpours in which the island city receives more than 150mm of rain, caused by an offshore vortex that is a “very small-scale, sub-grid system” that weather models cannot capture. She said:
“Low-pressure cyclonic systems, we can see coming. [But] this is the goblin that I haven’t seen who rushes in usually at night, creates havoc and leaves. Climate change is already contributing to these types of events: a whole lot of rain in smaller spells.”
As a coastal city, scientists told Carbon Brief that the city should be prepared to soak in 300mm of rain, but, because of choked drains, rivers and built infrastructure, it currently cannot even take in 100mm.
Mumbai’s monsoon ‘war room’
Fifteen minutes away from the observatory, a whiteboard in the Brihanmumbai Municipal Corporation’s (BMC) “monsoon war room” shows the state of affairs: rivers that should have been desilted by May are still only 66% done.
In its disaster control room three flights down, the phones will not stop ringing. The city’s residents, police and fire brigades are calling to report waterlogging, fallen branches and landslides.
While one giant screen streams live CCTV footage from 25 of the city’s worst traffic chokepoints, another screen shows live Doppler radar footage – when it is working.
“Whatever resources an emergency needs, we mobilise them from this control room,” a senior BMC disaster management official told Carbon Brief:
“If we get an orange alert from the IMD, all of our agencies, the navy, army: all of them get an alert message from us asking them to stand by.”
Many fault the BMC for delayed alerts, desilting and a city dug up beyond recognition. Officials say they are using all platforms – from X to SMS – to warn people about monsoon impacts. They blame TV channels that have “stopped carrying the news” – and people who have stopped watching it for weather updates – for a lack of awareness. The official told Carbon Brief:
“We have sufficient funds. You can’t reduce natural hazards and, in such a crowded city, to survive, the only thing that can save you is your wits.”
Watch, read, listen
ET TU, PETROSTATE? A Foreign Affairs essay by two US professors argued that, as the US’s energy exports have grown, it has “begun to behave more like a classic petrostate”, less likely to “embrace multilateralism and cooperate on international rules”.
ADRIAN VS ADANI: BBC World Service’s Life at 50C had a new documentary following Indigenous Queenslander Adrian Burragubba’s “battle against Adani[‘s]” coal mine in Australia’s Galilee Basin.
NO SHADE: Adaptation policy researcher Aditya Valiathan Pillai spoke to the Migration Story about heat stress and the “politics of shade”.
Coming up
- 16-26 June: SB42 climate talks, Bonn
- 16-20 June: 79th meeting of the World Meteorological Organization’s Executive Council, Geneva
- 23 June-4 July: International Seabed Authority legal and technical commission meeting (Part II), Kingston
- 23-27 June: States parties to the United Nations Convention on the Law of the Sea, 35th meeting, New York
Pick of the jobs
- Bruegel, energy and climate economist | Salary: Unknown. Location: Brussels
- The Economist, editorial intern for the digital department | Salary: £30,000. Location: London
- Bertha Foundation, fellowship for filmmakers, lawyers and jouranalists | Fellowship: Up to $64,900 for a year. Location: Remote
DeBriefed is edited by Daisy Dunne. Please send any tips or feedback to debriefed@carbonbrief.org.
This is an online version of Carbon Brief’s weekly DeBriefed email newsletter. Subscribe for free here.
The post DeBriefed 20 June 2025: Three years to ‘keep 1.5C alive’; Bonn talks turn ‘bitter’; Inside Mumbai’s monsoon ‘war room’ appeared first on Carbon Brief.
Climate Change
Pawa in Palau
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!
Climate Change
From firefighting to future-proofing: Preventing wildfires must be the priority
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.


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