A “collapse” of key Atlantic ocean currents would cause winter temperatures to plunge across northern Europe, overriding the warming driven by human activity.
That is according to new research, published in Geophysical Research Letters, which looks at the combined impact of the shutdown of the Atlantic Meridional Overturning Circulation (AMOC) and global warming on temperatures in northern Europe.
Scientists have warned that human-caused climate change is likely causing AMOC to weaken and that continued warming could push it towards a “tipping point”.
The study suggests that, in an intermediate emissions scenario, greenhouse gas-driven warming would not be able to outweigh the cooling impact of an AMOC collapse.
In this modelled world, one-in-10 winters in London could see cold extremes approaching -20C.
Winter extremes in Oslo in Norway, meanwhile, could plummet to around -48C.
The cold temperatures are projected to be driven by the loss of heat transfer from the tropics via ocean currents, as well as the spread of sea ice to northern Europe in the winter months.
The research does not look at when AMOC might tip – instead, it focuses on scenarios in the far future when this has already happened, so as to explore what impact it would have.
Lead author Dr René van Westen, a researcher in oceanography at Utrecht University, says Europe might stand alone as the one region set to get “cooler in a warmer world”. He tells Carbon Brief:
“If the AMOC collapses, we need to prepare for substantially cooler winters. Winter extremes will be very substantial for some regions. Temperatures could go down to -50C in Scandinavia. At -40C and lower in Scandinavia – everything breaks down over there.”
The research is being published alongside an interactive map, featured below, which highlights how a collapsed AMOC under different warming scenarios could impact temperature averages, extremes and sea ice across Europe.
‘Will warming or cooling win?’
AMOC is a system of ocean currents which plays a crucial role in keeping Europe warm. It transports warm water northwards from the tropics to Europe and cold, deep waters back southwards.
The potential collapse of these ocean currents – caused by the influx of freshwater from melting ice as well as rising air temperatures – is seen by some scientists as a “tipping point” that, once triggered, would be irreversible on human timescales.
However, there is significant scientific debate around whether human-caused climate change is causing the AMOC to slow down – and whether and when it might “tip”.
(The “tipping” of AMOC is often referred to as a “collapse”, “breakdown” or “shutdown”.)
Some scientists have argued that ocean currents have been slowing down since the mid-20th century, whereas others say there has been no weakening since the 1960s.
On the risks of an approaching tipping point, some researchers have estimated a collapse could occur this century, but others have questioned the robustness of the early warning signals being interpreted as evidence of a forthcoming shutdown.
(Regular direct measurements of AMOC’s strength started in 2004. To estimate the ocean currents’ health prior to this, scientists turn to a number of methods, including looking at palaeoclimate records, running climate model “hindcasts” and analysing historical patterns in sea surface temperature.)
A paper published last year by van Westen and colleagues, which ranked second in Carbon Brief’s round-up of the most talked-about climate papers of 2024, found that the present-day AMOC is on a trajectory towards tipping.
That paper set out some of the climate impacts of such an event, including a 10-30C drop in average monthly winter temperatures in northern Europe within a century and a “drastic change” in rainfall patterns in the Amazon.
The scientist’s latest offering provides a more detailed look at how an AMOC tipping event might impact Europe, using simulations produced by the Community Earth System Model (CESM).
The research models the impact of an AMOC collapse in combination with the impacts of human-caused climate change, instead of looking at the collapse of the ocean currents in isolation.
Van Westen says the research was designed to answer the question of how warming from greenhouse gas emissions could offset cooling from an AMOC shutdown. He tells Carbon Brief:
“[A question we wanted to address was] what would happen in a scenario where we have climate change and an AMOC collapse. Will it get cooler over Europe, or will it get warmer? Will regional warming win or will the cooling win?”
Simulating AMOC ‘collapse’
To answer this question, the scientists run a raft of climate simulations, exploring different combinations of global temperature rise and AMOC collapse.
Specifically, the scientists explore the collapse of AMOC under three scenarios:
- An “intermediate” climate scenario (RCP4.5), which is in line with current global climate policies.
- A very high-emissions scenario (RCP8.5) where warming hits 4C above the pre-industrial average by 2100.
- A “pre-industrial” scenario, without any human-caused global warming.
Across all three scenarios, the researchers run multiple simulations 500 years into the future, stabilising global temperature rise at 2C and above 4C from 2100 onwards. The researchers explore scenarios where AMOC is stable and when it has tipped.
The paper does not discuss the level of warming at which AMOC might tip – instead, it focuses on a point in the future after it has occurred, when the ocean currents and the climate have “equilibrated to a new background state”.
To simulate an AMOC collapse in the climate model under the two warming pathways, the researchers apply high levels of freshwater forcing to the north Atlantic.
Van Westen acknowledges the level of freshwater forcing applied to the model to create an AMOC shutdown is “unrealistic”, but says the adjustment is necessary to override a “bias” in climate models. He explains:
“[Climate models] have an overly stable AMOC. So, we need to add this kind of freshwater flux to get the AMOC in a more unstable regime which corresponds to actual observations.”
The paper focuses largely on impacts under the intermediate scenario with AMOC collapse. Under this combination, AMOC shutdown causes some global cooling, resulting in a world that is around 2C warmer than pre-industrial levels.
Prof Stefan Rahmstorf, a professor of physics of the oceans at Potsdam University who was not involved in the research, tells Carbon Brief the new study is “highly welcome”. He explains that “not many” studies have investigated the combined impact of global warming with AMOC collapse since a paper he co-authored in 1999, and adds:
“[The new study] uses a sophisticated climate model with good regional resolution – far better than what was possible 26 years ago. The model confirms the long-standing concern that an AMOC collapse would have massive impacts on European climate, in this case focusing on temperature extremes.”
Dr Alejandra Sanchez-Franks, senior research scientist in the marine physics and ocean climate group at National Oceanography Centre, who was also not involved in the research, says the study’s conclusions should not be used to explain how the European climate will respond in the near-term to changes in the strength of AMOC. She tells Carbon Brief:
“The study uses an idealised experiment with unrealistic freshwater changes to force an AMOC collapse. Very importantly, the author’s conclusions refer to the European climate 200 years after an AMOC change and do not describe what will happen to European temperatures and sea ice in the years and decades following an AMOC collapse.
“Therefore, the study does not serve to tell us how an AMOC tipping point or collapse will affect us immediately.”
‘Out of the freezer and into the frying pan’
The most “striking” finding of the paper, according to van Westen, is that an AMOC collapse in a world that is 2C warmer will result in a Europe that is cooler than it is today.
The research notes that – under this scenario – north-west Europe is set to face “profound cooling”, characterised by more intense winter extremes.
Summer temperatures, on the other hand, would be expected to remain just slightly cooler than they would in a pre-industral climate – meaning that Europeans would experience dramatic swings in temperatures throughout the year.
Increased winter storms and greater day-to-day temperature fluctuations are also expected in this scenario. This is due to a greater temperature contrast between northern Europe and southern Europe, which would be less impacted by a weakened AMOC.
The research notes that cooling from the reduced heat transfer from ocean currents would be amplified by “extensive” sea ice expansion to the coasts of north-west Europe. (Sea ice reflects incoming solar sunlight, resulting in less heat uptake and cooler temperatures overall.)
The map below shows the extent of sea ice in February under the scenario where AMOC collapses and the world is 2C warmer. It shows how Arctic sea ice – when at its yearly maximum – would cover the coasts of Scandinavia and much of the island of Great Britain.
Prof Tim Lenton, chair of climate change and Earth system science at the University of Exeter, who was not involved in the study, tells Carbon Brief it is “hard to over-stress how different” the climate simulated by the model is from present-day conditions. He says:
“The extreme winters would be like living in an ice age. But at the same time summer temperature extremes are barely impacted – they are slightly cooler than they would be due to global warming, but still with hotter extremes than the preindustrial climate.
“This means the seasonality of the climate is radically increased. In extreme years it would be like coming out of the freezer into a frying pan of summer heatwaves.”
The research also looks at the impacts of a shutdown of AMOC in a world that is 4C warmer.
It suggests that, under this scenario, cooling related to the shutdown of ocean currents would not outweigh global warming. Northern Europe would not experience extensive sea-ice expansion or the strong cooling projected under the 2C scenario.
Instead, temperatures would be expected to increase throughout the year and particularly in the summer months. However, northern Europe would be expected to see warming below the global average.
Frigid cities
While the paper itself uses the Dutch town of De Bilt as a case study, the researchers have published projections for a range of European cities under the scenarios explored in the study.
For example, the data shows that, under AMOC collapse in a 2C-warmer world, London could experience an average winter temperature of 1.9C, roughly 17.6 freezing days each year and one-in-10-year cold extremes of -19.3C.
In the Norwegian capital of Oslo, average winter temperatures are projected to plunge to -16.5C, with maximum daily temperatures not surpassing 0C for almost half the year, or 169 days. The research suggests the Norwegian city could experience cold extremes of -47.9C.
The map below shows projected cold extremes under 2C of warming and AMOC collapse in cities in Belgium, France, Ireland, the Netherlands, Switzerland and the UK. It shows how temperatures could drop to -29.7 in Edinburgh, -19.3C in London and -18C in Paris.
Van Westen says the findings are “highly relevant for society and policymakers” because they “shift the narrative” about the direction of Europe’s future climate. He explains:
“Parts of the Netherlands and parts of the UK will experience spectacular cold extremes down to -20C or even lower. Our societal structure and our infrastructure is not built for these cold extremes.”
The paper is being published alongside an interactive map, shown below, that shows ice cover, temperature averages and extremes across Europe under five of the scenarios explored in the study. These are: a pre-industrial world with a stable AMOC, a pre-industrial world with a collapsed AMOC, a 2C world with a stable AMOC, a 2C world with a collapsed AMOC and a 4C world with a collapsed AMOC.
Future research
Scientists not involved in the study said the work would need to be followed up with further exploration of the interplay between global warming and potential AMOC collapse.
Dr Bablu Sinha, leader of climate and uncertainty, marine systems modelling at the National Oceanography Centre, told Carbon Brief:
“Given that observational data is limited, theoretical climate modelling approaches need to be taken to properly investigate this topic. Van Westen and Baatsen motivate the need for more detailed investigation into the combined impacts of global warming and AMOC decline on European extreme temperatures.”
Dr Yechul Chin, researcher at Seoul National University’s climate system lab, tells Carbon Brief:
“Although [this research] demonstrates the potential for more extreme weather under combined global warming and AMOC collapse scenarios, significant uncertainties remain that must be resolved before we can quantify risks or devise robust mitigation strategies.
“Projections about AMOC have a large spread and it means that alternative AMOC trajectories and different levels of warming could substantially widen the range of possible outcomes.”
His comments are echoed by Rahmstorf from Potsdam University, who points out that the “exact outcome” for Europe hinges on the development of “two opposing trends” – global warming due to greenhouse gases and regional cooling due to AMOC weakening. He says:
“The balance between those two will depend on the speed and extent of these trends and will, therefore, depend on the emission and AMOC weakening scenarios.
“Therefore, the more scenarios will be explored with different models in future, we will see a range of different outcomes for Europe as well as other parts of the world. A large uncertainty in this respect will remain.”
The post Ocean current ‘collapse’ could trigger ‘profound cooling’ in northern Europe – even with global warming appeared first on Carbon Brief.
This week our powerful Pacific team is in Palau for the Pacific Islands Forum Leaders Meeting. This is a major moment in our campaigns for Pacific climate justice and to stop deep sea mining. So what’s it all about, what can we expect over the coming days, and why is this year’s meeting in particular so important? Read on to find out!
*Pawa is Melanesian word meaning collective power.
Meet Moemoana Schwenke, our Pacific Climate Campaigner
“When you love something deeply, you do everything you can to protect it.”
What is the Pacific Islands Forum (PIF)?
The Pacific Islands Forum, or ‘PIF’, is our region’s most important political organisation. It is where countries of the Pacific — including Australia and New Zealand — come together to collaborate on shared challenges and to set collective goals.
The PIF Leaders Meeting is an annual weeklong event that includes a dedicated meeting of the Pacific’s small island developing states (PSIDS), many special side events organised by Pacific civil society, the leaders’ meeting itself, and more. At the end of the week, leaders issue a Forum Communiqué, capturing what they have agreed on, their shared priorities and the actions they will take together.
This year’s meeting is being held in the beautiful northern Pacific nation of Palau, the same place our Pacific team gathered back in January to plan for the year.
What’s at stake this year?
Climate change has dominated the PIF for decades. Pacific leaders have been crystal clear it is their number one priority, and the annual gathering is the moment they can exert maximum pressure on Australia over its fossil fuel record.
The voyage to COP31
This year’s meeting comes less than three months before COP31, where Australia will take on the role of President of Negotiations — a role it has committed to undertaking in partnership with the Pacific — and less than a month before the ‘Pacific Pre-COP’, to be held in Fiji and Tuvalu.
Following a fraught round of mid-year negotiations in Bonn, PIF leaders will need to set out a clear vision and priorities for COP31. These include accelerating a just global transition away from fossil fuels, defending science as the foundation of international climate cooperation, and increasing the availability and accessibility of finance for renewable energy and climate adaptation.
Accountability for Australian fossil fuel exports
Since the last PIF Leaders Meeting, Australia has signed the Belém Declaration on the Transition Away from Fossil Fuels. The declaration reaffirmed the legally binding commitment to help limit global warming to 1.5°C and recognised that this is incompatible with new fossil fuel production. Yet, Australia has continued to approve new coal and gas projects, including at least five since the last PIF Leaders Meeting.
What is Greenpeace doing?
We’re going big this year, taking six members of our team to Palau to support Pacific leaders to hold the line, hold Australia accountable, and show the world what’s at stake. We’ll lobby leaders, hold press conferences, share our messages with the world, and support our incredible local partners in Palau.
How can you get involved?
PIF is the first in a drumbeat of major moments where we’ll be carrying the voices of the Pacific to the world. Come October we’ll be voyaging to Fiji on our ship Oceania for the Pacific Pre-COP, and in November we’ll be off to Antalya for the world’s climate negotiations (COP31).
Learn more about the Pacific way to a fossil fuel free future by checking out our report and exhibition.
Follow our journey, and check back here for more ways to join the movement for climate justice. Together we have the pawa!
Gill Einhorn is head of the Forest Future Alliance and Natalie Çilem is community lead of the Global Wildfire Leadership Network.
Wildfires have devastated communities across the world this summer, claiming lives, displacing thousands of people and leaving billions in economic damage in their wake. In Europe alone, wildfires have already caused an estimated €19 billion in losses this year.
They are an economic, financial and public health challenge that is growing faster than many governments and markets are prepared for – and exposing the real costs of poor land management.
A system built for recovery, not resilience
Far more money is currently spent responding to the disastrous effects of wildfires than preventing them in the first place. The United Nations Environment Programme estimates that more than half of wildfire-related spending goes towards response, while planning receives only around 0.2 percent. This problem is not limited to wildfires; over 95 percent of disaster aid between 2005 and 2017 was allocated to response, and less than 4 percent was directed towards prevention or preparedness.
Forests are critical, but without investment in how land is managed and protected, their value is neither stable nor guaranteed. Protecting forests requires investing not only in conservation, but in the conditions that keep forests standing.
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Each dollar invested in wildfire-resistant construction could save around $210 in avoided future economic losses, according to a report by the World Economic Forum and Forest Future Alliance. Despite this evidence that prevention can significantly reduce future costs, wildfire resilience remains chronically underfunded.
This spending discrepancy is creating significant challenges for insurers, asset owners and financial institutions. Global insured losses from natural catastrophes reached $107 billion in 2025, with wildfires, floods and storms accounting for 92 percent of claims.
In this context, insurers are reassessing where and how they are willing to underwrite risk. Around 56 percent of global wildfire losses between 2000 and 2023 were uninsured. In some high-risk areas, insurers are scaling back coverage altogether, leaving homeowners, businesses and governments to shoulder a growing share of the costs – making it increasingly difficult to break even.
Proven solutions are already paying off
In many regions, wildfires are driven not by natural causes but by the deliberate clearing of land for agriculture. Degraded landscapes are becoming drier, more flammable and increasingly vulnerable to catastrophic loss, creating a vicious cycle of deforestation, economic damage and rising emissions.
The answer is not simply stronger firefighting capacity. Governments, investors and businesses must work together to shift capital upstream into prevention, resilience and long-term landscape stewardship of healthy forests. That means planting appropriately, investing in heat-resistant species, exploring approaches that minimise fire footprints through active management, and exploring the AI and technology solutions that are burgeoning.
Solutions to this already exist and are proven to have an impact. Following devastating wildfires year-on-year, Portugal shifted its approach to wildfire management, increasing prevention spending within its national rural fire management system from around 20 percent in 2017 to approximately 60 percent in 2022. While many countries remain locked in a reactive cycle of disaster response, public policy can shift investment upstream and make resilience a priority before fires occur.
Indigenous communities have long used proactive land stewardship to reduce wildfire risk while supporting healthy and productive landscapes. For example, the Cheslatta Carrier Nation in British Columbia traditionally managed fuels through cultural fire practices but now implements mechanised fuel removal methods under commercial agreements. By combining Indigenous stewardship with sustainable forest management, Cheslatta is generating community benefits while also boosting wildfire prevention.
Resilience can also be strengthened through finance and technology. FireSat, a partnership led by Earth Fire Alliance with Google.org, the Gordon and Betty Moore Foundation and Muon, is a satellite constellation designed for rapid wildfire detection. Scanning every 20 minutes, it can detect fires 400 times smaller than current systems and track them through smoke and darkness in almost real time. In California alone, FireSat could prevent up to 350,000 acres from burning each year. It has recently received significant new investments allowing it to expand towards a constellation of more than 50 satellites that will monitor every point on Earth every 20 minutes or less.
In Brazil’s Pantanal, the Embrace the Forest initiative uses AI-powered detection towers across 2.5 million hectares to support earlier intervention and faster response. During the severe 2024 fire season, the initiative contributed to a 40 percent reduction in burned area compared to 2020.
These examples illustrate what is possible when resilience is treated as an investment priority rather than a recovery cost. But we must ensure funding for these measures is scaled before disaster strikes. Initiatives like the Global Wildfire Leadership Network (GWLN) are key, bringing together corporate decision-makers, investors, insurers, governments and Indigenous leaders to direct investment towards prevention and align finance, technology and stewardship to protect nature, safeguard communities and strengthen future economic stability. With a goal of doing more together than the sum of our parts, the network focuses on Forest Future Alliance GWLN Solutions Labs – where partners sign up with the intent to collaborate.
Rewarding prevention
Financial incentives must be created that reward prevention. This can be done by scaling public-private partnerships, supporting long-term landscape stewardship, investing in community capacity including Indigenous wisdom and technology. Ultimately, our terrestrial natural reserves are critical infrastructure that support resilient economies and thriving communities.
One in three people are dependent on forest services, goods and economic opportunities for survival, so it’s in all our interests to protect what we have. Forests support cooling, water and food security – and are a very cost-effective way of removing carbon dioxide from the atmosphere, where done appropriately.
UN chief warns climate crisis “in overdrive” as El Niño threatens to fuel the fire
No sector can solve this challenge alone. The benefits of wildfire resilience are shared across communities, governments, insurers, investors, utilities and businesses. A single intervention can protect homes and livelihoods, reduce insurance claims, secure water supplies and lower future public costs. Because the benefits are shared, the solutions must be too. Coalitions of actors can take proven approaches further than any one individual or organisation could alone.
As wildfires continue to burn at an unprecedented scale, the opportunity now is to roll out solutions, shift investment upstream and build a future where resilience, rather than recovery, becomes the foundation of thriving economies.
The post From firefighting to future-proofing: Preventing wildfires must be the priority appeared first on Climate Home News.
From firefighting to future-proofing: Preventing wildfires must be the priority
Methane is a powerful greenhouse gas and the second-largest contributor to global warming after carbon dioxide (CO2).
Methane traps heat in the atmosphere more efficiently than CO2, but has a significantly shorter lifespan, fading after just a few decades.
Therefore, reducing emissions of methane – a gas primarily produced by agriculture, fossil fuels and waste management – is a powerful option for limiting global warming in the near-term.
Yet climate strategies and models often only focus on CO2, or combine all greenhouse gases into one metric known as “CO2 equivalent”.
The latter approach makes reducing methane emissions dependent on modelling choices and assumptions about the “equivalence” of methane and CO2.
It hides the opportunities and challenges linked to methane’s high warming and short lifetime.
In a new study, published in Communications Earth & Environment, we offer a different perspective that “decouples” CO2 and methane reduction and takes global warming limits as a starting point for determining the required level of methane cuts.
We show that, even under the most ambitious existing national net-zero targets, an absence of methane reduction leads to peak warming that exceeds 1.85C above pre-industrial levels.
The study highlights that, to limit peak warming to well-below 2C, net-zero CO2 targets must be complemented by stringent methane emissions cuts.
CO2 equivalent
How much methane corresponds to one tonne of CO2?
The question is as difficult to answer as: ‘how much spaghetti equals a chicken?’ You could compare the two meals according to their calories, protein content or cost. Each metric can be convenient, but is only valid for that specific comparison – no amount of spaghetti is the same as a chicken.
The same is true for the conversion of emissions of methane and other gases to CO2-equivalent emissions. It can be convenient, as it allows different gases to be compared or combined into a single number. This is why the metric is used in climate targets or evaluating the effectiveness of different mitigation options.
But, because methane and CO2 have different atmospheric lifetimes and warming properties, any conversion is only valid for a chosen time horizon and a chosen baseline.
Depending on the assumptions baked into calculations, methane mitigation can either appear as an immediate priority or framed as almost unnecessary.
There are a number of metrics that scientists use to convert greenhouse gases – whether methane, hydrofluorocarbons or nitrous oxide – into CO2-equivalent emissions:
- “GWP20” measures how much heat a greenhouse gas traps in the atmosphere over a 20-year period, relative to CO2. It emphasises urgent methane mitigation but has been criticised for its implicit discounting of future damages.
- “GWP100” looks at a 100-year timeline. It gives more weight to long-term warming and is used in “integrated assessment models” (IAMs) used by scientists, national emission reporting to the UN and by the GHG Protocol used by companies.
- “GWP*” considers the rate of emissions, rather than warming over a fixed time horizon. Under GWP*, very limited methane reductions bring CO2-equivalent emissions to zero, meaning remaining methane emissions can be designated as causing “no additional warming”. (This interpretation remains controversial as it assumes the continuation of historical levels of warming.)
IAMs are the tools used to generate future emissions scenarios. Because they combine CO2 and methane emissions, the impact of methane emission cuts alone is difficult to isolate in existing emission scenarios.
IAM-generated scenarios also assume mitigation decisions driven by costs. Combinations of CO2 and methane emission pathways that are not purely cost-effective are, therefore, not represented, even though climate policy is messy and emission pathways are rarely cost-effective in the real world.
Only a few countries – including Japan, Mexico and South Korea – specify methane mitigation targets.
A different approach
In our study, we separate CO2 and methane emissions and treat them as independent.
Instead of choosing a conversion method, we suggest that states and organisations set a limit on peak global warming first, then, based on their existing net-zero targets, determine the minimum compatible methane reduction target.
Companies and countries around the world have set net-zero targets focused on CO2, as well as those that include all greenhouse gases. As a result, our research looks at the necessary methane reductions for both types of goal. We consider scenarios where companies or countries deliver linear – in other words, steady – emissions reductions to reach net-zero.
Using a simple climate model, we systematically combined methane and CO2 (or greenhouse gas) mitigation pathways starting in 2025 and calculated peak warming.
The figure below shows how peak warming depends on both the year of reaching net-zero CO2 and the level of methane cuts.
The blue arrows in the figure show that to limit warming to 1.7C under a 2050 net-zero CO2 scenario, methane emissions would need to fall by at least 69% by 2050, relative to 2020.
Our research also finds that, if an organisation or country’s 2050 net zero-target covers all greenhouse gases, its methane emissions would need to fall by 63% instead.
However, under current policies, methane emissions are expected to increase by around 20% by 2050, relative to 2020. We find that this pathway would result in peak warming above 2C by 2050 – even if global CO2 emissions were to reach net-zero by that date (see purple bar on the right-hand side of the figure above).
The figure also shows how, if methane emissions remained at 2020 levels and net-zero CO2 was delivered by 2040 or later, warming would exceed 1.85C. This level of warming is above what has been argued as consistent with the Paris Agreement’s “well-below” 2C limit.
Conversely, cutting methane emissions by around one-third – in line with the Global Methane Pledge target for 2030 – could reduce peak warming by 0.15C, of which 0.05C could be delivered by interventions that come at no net cost. These are shown by the orange and red bars, respectively, on the figure above.
The table below highlights the minimum compatible methane cuts for three different peak warming levels and net-zero CO2 or greenhouse-gas emission targets.
| Peak warming | Year of net-zero CO2 emissions | Year of net-zero greenhouse-gas emissions | ||||
| 2050 | 2060 | 2100 | 2050 | 2060 | 2100 | |
| 1.7C | -69% | – | – | -63% | – | – |
| 1.8C | -32% | -56% | – | -11% | -47% | – |
| 2C | +8% | -8% | -83% | >50% | +33% | -78% |
Minimum methane emission reductions between 2020 and the year of net-zero emissions, consistent with peak warming of 1.7C, 1.8C, and 2.0C at 50% likelihood, assuming linear emission trajectories. For some net-zero targets and peak warming levels, there are no compatible methane mitigation targets (indicated by “–”).
Remaining carbon budget
The global carbon budget refers to the amount of cumulative CO2 emissions allowable while still meeting a particular global warming threshold.
The 2021 climate science report from the Intergovernmental Panel on Climate Change (IPCC) and a 2023 Nature study estimated that, by 2025, the remaining carbon budget for holding warming to 2C would be around 1,000-1,150bn tonnes of CO2 (GtCO2).
We find that these estimates are founded on the assumption of methane reductions of 27-35% by 2050, relative to a 2020 baseline. (A 2024 Communications Earth & Environment study reached similar conclusions.)
Under the GWP* metric, where methane emissions are only cut to maintain “no additional warming”, the remaining carbon budget would be constrained. The best estimate of a 2C budget shrinks by around 30% to approximately 750GtCO2.
Finally, if methane emissions are not cut at all in the future, our findings suggest that the remaining carbon budget for 1.7C of global warming has, in effect, already been exhausted.
Our analysis shows how peak warming depends on both CO2 and methane reduction – and how methane-specific targets can help refine existing net-zero targets.
Crucially, we show that complementing net-zero CO2 targets with stringent methane cuts is necessary to limit peak warming to well-below 2C.
Weber, K. et al. (2026) Limiting warming by CO2 and methane mitigation in an expanded scenario space, Communications Earth & Environment, doi:10.1038/s43247-026-03832-1
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