The first-ever international conference on the contentious topic of “overshoot” was held last week in a palace in the small town of Laxenburg in Austria.
The three-day conference brought together nearly 200 researchers and legal experts to discuss future temperature pathways where the Paris Agreement’s “aspirational” target to limit global warming to 1.5C is met “from above, rather than below”.
Overshoot pathways are those which exceed the 1.5C limit – before being brought back down again through techniques that remove carbon from the atmosphere.
The conference explored both the feasibility of overshoot pathways and the legal frameworks that could help deliver them.
Researchers also discussed the potential consequences of a potential rise – and then fall – of global temperatures on climate action, society and the Earth’s climate systems.
Speaking during a plenary session, Prof Joeri Rogelj, a professor of climate science and policy at Imperial College London, said that “moving into a world where we exceed 1.5C and have to manage overshoot” was an exercise in “managing failure”.
He said that it was “essential” that this failure was acknowledged, explaining that this would help set out the need to “minimise and manage” the situation and clarify the implications for “near-term action” and “long-term [temperature] reversal”.
Below, Carbon Brief draws together some of the key talking points, new research and discussions that emerged from the event.
- Defining overshoot
- Mitigation ambition and 1.5C viability
- Carbon removal
- Impacts of overshoot
- Adaptation
- Legal implications and loss and damage
- Communication challenges and next steps
Defining overshoot
The study of temperature overshoot has grown in recent years as the prospects of limiting global temperature rise to 1.5C have dwindled.
Conference organiser Dr Carl-Friedrich Schleussner – a senior research scholar at the International Institute for Applied Systems Analysis (IIASA) – explained the event was designed to bring together different research communities working on a “new field of science”.
He told Carbon Brief:
“If we look at [overshoot] in isolation, we may miss important parts of the bigger picture. That’s why we also set out the conference with very broad themes and a very interdisciplinary approach.”
The conference was split between eight conference streams: mitigation ambition; carbon dioxide removal (CDR); Earth system responses; climate impacts; tipping points; adaptation; loss and damage; and legal implications.
There was also a focus on how to communicate the concept of overshoot.
In simple English, “overshoot” means to go past or beyond a limit. But, in climate science, the term implies both a failure to meet a target – as well as subsequent action to correct that failure.
Today, the term is most often deployed to describe future temperature trajectories that exceed the Paris Agreement’s 1.5C limit – and then come back down.
(In the Intergovernmental Panel on Climate Change’s (IPCC’s) fifth assessment cycle, completed in 2014, the term was used to describe a potential rise and then fall of CO2 concentrations above levels recommended to meet long-term climate goals. A recent “conceptual” review of overshoot noted this was because, at the time, CO2 concentrations were the key metric used to contextualise emissions reductions).
The plot below provides an illustration of three overshoot pathways. The most pronounced pathway sees global temperatures rise significantly above the 1.5C limit – before eventually falling back down again as carbon dioxide is pulled from the atmosphere at scale.
In the second and third pathways, global temperature rise breaches the limit by a smaller margin, before either falling enough just to stabilise around 1.5C, or dropping more dramatically due to larger-scale carbon removals.
In an opening address to delegates, Prof Jim Skea, who is the current chair of the IPCC, acknowledged the scientific interpretation of overshoot was not intuitive to non-experts.
“The IPCC has mainly used two words in relation to overshoot – “exceeding” and “limiting”. To a lay person, these can sound like opposites. Yet we know that a single emissions pathway can both exceed 1.5C in the near term and limit warming to 1.5C in the long term.”
Noting that different research communities were using the term differently, Skea urged researchers to be precise with terminology and stick to the IPCC’s definition of overshoot:
“We should give some thought to communication and keep this as simple as possible. When I look at texts, I hear more poetic words like “surpassing” and “breaching”. I would urge you to keep the range of terms as small as possible and make sure that we’re absolutely using them consistently.”
In the glossary for its latest assessment cycle, AR6, the IPCC defines “overshoot” pathways as follows:
IIASA’s Schleussner stressed that not all pathways that go beyond 1.5C qualify as overshoot pathways:
“The most important understanding is that overshoot is not any pathway that exceeds 1.5C. An overshoot pathway is specific to this being a period of exceedance. It is going to come back down below 1.5C.”
Mitigation ambition and 1.5C viability
Perhaps the most prominent topic during the conference was the implications of overshoot for global ambition to cut carbon emissions and the viability of the 1.5C limit.
Opening the conference, IIASA director general Prof Hans Joachim Schellnhuber shared his personal view that “1.5C is dead, 2C is in agony and 3C is looming”.
In a pre-recorded keynote speech, Ralph Regenvanu, Vanuatu’s minister for climate change, called for a rejection of the “normalisation of overshoot” and argued that “we must treat 1.5C as the absolute limit that it is” and avoid backsliding. He added:
“Minimising peak warming must be our lodestar, because every tenth of a degree matters.”
Prof Skea opened his keynote with some theology:
“I’m going to start with the prayer of St Augustine as he struggled with his youthful longings: ‘Lord grant me chastity and continence, but not yet.’ And it does seem that this is the way that the world as a whole is thinking about 1.5C: ‘Lord, limit warming to 1.5C above pre-industrial levels, but not yet.’”
Referencing the “lodestar” mentioned by Regenvanu, Skea warned that it is light years away and, “unless we act with a sense of urgency, [1.5C is] likely to remain just as remote”.
Speaking to Carbon Brief on the sidelines of the conference, Skea added:
“We are almost certain to exceed 1.5C and the viability of 1.5C is now much more referring to the long-term potential to limit it through overshoot.”
Schleussner told Carbon Brief that the framing of 1.5C in the conference is “one that further solidifies 1.5C as the long-term limit and, therefore, provides a backstop against the idea of reducing or backsliding on targets”.
If warming is going to surpass 1.5C, the next question is when temperatures are going to be brought back down again, Schleussner added, noting that there has been no “direct” guidance on this from climate policy:
“The [Paris Agreement’s] obligation to “pursue efforts” [to limit global temperature rise by 1.5C] points to doing it as fast as possible. Scientifically, we can determine what this means – and that would be this century. But there’s no clear language that gives you a specific date. It needs to be a period of overshoot – that is clear – and it should be as short as possible.”
In a parallel session on the “highest possible mitigation ambition under overshoot”, Prof Joeri Rogelj, professor of climate science and policy at Imperial College London, outlined how the recent ruling from the International Court of Justice (ICJ) provides guidance to countries on the level of ambition in their climate pledges under the Paris Agreement, known as “nationally determined contributions” (NDCs). He explained:
“[The ruling] highlights that the level of NDC ambition is not purely discretionary to a state and that every state must do its utmost to ensure its NDC reflects the highest possible ambition to meet the Paris Agreement long-term temperature goal.”
Rogelj presented some research – due to be published in the journal Environmental Research Letters – on translating the ICJ’s guidance “into a framework that can help us to assess whether an NDC indeed is following a standard of conduct that can represent the highest level of ambition”. He showed some initial results on how the first two rounds of NDCs measure up against three “pillars” covering domestic, international and implementation considerations.
In the same session, Prof Oliver Geden, senior fellow and head of the climate policy and politics research cluster at the German Institute for International and Security Affairs and vice-chair of IPCC Working Group III, warned that the concept of returning temperatures back down to 1.5C after an overshoot is “not a political project yet”.
He explained that there is “no shared understanding that, actually, the world is aiming for net-negative”, where emissions cuts and CDR together mean that more carbon is being taken out of the atmosphere than is being added. This is necessary to achieve a decline in global temperatures after surpassing 1.5C.
This lack of understanding includes developed countries, which “you would probably expect to be the frontrunners”, Geden said, noting that Denmark is the “only developed country that has a quantified net-negative target” of emission reductions of 110% in 2050, compared to 1990 levels. (Finland also has a net-negative target, while Germany announced its intention to set one last year. In addition, a few small global-south countries, such as Panama, Suriname and Bhutan, have already achieved net-negative.)
Geden pondered whether developed countries are a “little bit wary to commit to going to net-negative territory because they fear that once they say -110%, some countries will immediately demand -130% or -150%” to pay back a larger carbon debt.
Carbon removal
To achieve a decline in global temperatures after an initial breach of 1.5C would require the world to reach net-negative emissions overall.
There is a wide range of potential techniques for removing CO2 from the atmosphere, such as afforestation, direct air capture and bioenergy with carbon capture and storage (BECCS). Captured carbon must be locked away indefinitely in order to be effective at reducing global temperatures.
However, despite its importance in achieving net-negative emissions, there are “huge knowledge gaps around overshoot and carbon dioxide removal”, Prof Skea told Carbon Brief. He continued:
“As it’s very clear from the themes of this conference, we don’t altogether understand how the Earth would react in taking carbon dioxide out of the atmosphere. We don’t understand the nature of the irreversibilities. And we don’t understand the effectiveness of CDR techniques, which might themselves be influenced by the level of global warming, plus all the equity and sustainability issues surrounding using CDR techniques.”
Skea notes that the seventh assessment cycle of the IPCC, which is just getting underway, will “start to fill these knowledge gaps without prejudging what the appropriate policy response should be”.
Prof Nebojsa Nakicenovic, an IIASA distinguished emeritus research scholar, told Carbon Brief that his “major concern” was whether there would be an “asymmetry” in how the climate would respond to large-scale carbon removal, compared to its response to carbon emissions.
In other words, he explained, would global temperatures respond to carbon removal “on the way down” in the same way they did “on the way up” to the world’s carbon emissions.
Nakicenovic noted that overshoot requires a change in focus to approaching the 1.5C limit “from above, rather than below”.
Schleussner made a similar point to Carbon Brief:
“We may fail to pursue [1.5C] from below, but it doesn’t relieve us from the obligation to then pursue it from above. I think that’s also a key message and a very strong overarching message that’s going to come out from the conference that we see…that pursuing an overshoot and then decline trajectory is both an obligation, but it also is well rooted in science.”
Reporting back to the plenary from one of the parallel sessions on CDR, Dr Matthew Gidden, deputy director of the Joint Global Change Research Institute at the Pacific Northwest National Laboratory, also noted another element of changing focus:
“When we’re talking about overshoot, we have become used to, in many cases, talking about what a net-zero world looks like. And that’s not a world of overshoot. That’s a world of not returning from a peak. And so communicating instead about a net-negative world is something that we could likely be shifting to in terms of how we’re communicating our science and the impacts that are coming out of it.”
On the need for both CDR and emissions cuts, Gidden noted that the discussions in his session emphasised that “CDR should not be at the cost of mitigation ambition”. But, he added, there is still the question of how “we talk about emission reductions needed today, but also likely dependence on CDR in the future”.
In a different parallel session, Prof Geden also made a similar point, noting that “we have to shift CDR from being seen as a barrier to ambition to an enabler of even higher ambition, but not doing that by betting on ever more CDR”.
Among the research presented in the parallel sessions on CDR was a recent study by Dr Jay Fuhrman from the JGCRI on the regional differences in capacity to deploy large-scale carbon removal. Ruben Prütz, from the Potsdam Institute for Climate Impact Research, presented on the risks to biodiversity from large-scale land-based CDR, which – in some cases – could have a larger impact than warming itself.
In another talk, the University of Oxford’s Dr Rupert Stuart-Smith explored how individual countries are “depending very heavily on [carbon] removals to meet their climate targets”. Stuart-Smith was a co-author on an “initial commentary” on the legal limits of CDR, published in 2023. This has been followed up with a “much more detailed legal analysis”, which should be published “very soon”, he added.
Impacts of overshoot
Since the Paris Agreement and the call for the IPCC to produce a special report on 1.5C, research into the impacts of warming at the aspirational target has become commonplace.
Similarly, there is an abundance of research into the potential impacts at other thresholds, such as 2C, 3C and beyond.
However, there is comparatively little research into how impacts are affected by overshoot.
The conference included talks on some published research into overshoot, such as the chances of irreversible glacier loss and lasting impacts to water resources. There were also talks on work that is yet to be formally published, such as the risks of triggering interacting tipping points under overshoot.
Speaking in a morning plenary, Prof Debra Roberts, a coordinating lead author on the IPCC’s forthcoming special report on climate change and cities and a former co-chair of Working Group II, highlighted the need to consider the implications of different durations and peak temperatures of overshoot.
For example, she explained, it is “important to know” whether the impacts of “overshoot for 10 years at 0.2C above 1.5C are the same as 20 years at 0.1C of overshoot”.
Discussions during the conference noted that the answer may be different depending on the type of impact. For heat extremes, the peak temperature may be the key factor, while the length of overshoot will be more relevant for cumulative impacts that build up over time, such as sea level rise.
Similarly, if warming is brought back down to 1.5C after overshoot, what happens next is also significant – whether global temperature is stabilised or net-negative emissions continue and warming declines further. Prof Schleussner told Carbon Brief:
“For example, with coastal adaptation to sea level rise, the question of how fast and how far we bring temperatures back down again will be decisive in terms of the long-term outlook. Knowing that if you stabilise that around 1.5C, we might commit two metres of sea level rise, right? So, the question of how far we can and want to go back down again is decisive for a long-term perspective.”
One of the eight themes of the conference centred specifically on the reversibility or irreversibility of climate impacts.
In his opening speech, Vanuatu’s Ralph Regenvanu warned that “overshooting 1.5C isn’t a temporary mistake, it is a catalyst for inescapable, irreversible harm”. He continued:
“No level of finance can pull back the sea in our lifetimes or our children’s. There is no rewind button on a melted glacier. There is no time machine for an extinct species. Once we cross these tipping points, no amount of later ‘cooling’ can restore our sacred reefs, it cannot regrow the ice that already vanished and it cannot bring back the species or the cultures erased by the rising tides.”
As an example of a “deeply, deeply irreversible” impact, Dr Samuel Lüthi, a postdoctoral research fellow in the Institute of Social and Preventive Medicine at the University of Bern, presented on how overshoot could affect heat-related mortality.
Using mortality data from 850 locations across the world, Lüthi showed how projections under a pathway where warming overshoots 1.5C by 0.1-0.3C, before returning to 1.5C by 2100 has 15% more heat-related deaths in the 21st century than a pathway with less than 0.1C of overshoot.
His findings also suggested that “10 years of 1.6C is very similar [in terms of impacts] to five years of 1.7C”.
Extreme heat also featured in a talk by Dr Yi-Ling Hwong, a research scholar at IIASA, on the implications of using solar geoengineering to reduce peak temperatures during overshoot.
She showed that a world where a return to 1.5C had been achieved through geoengineering would see different impacts from a world where 1.5C was reached through cutting emissions. For example, in her modelling study, while geoengineering restores rainfall levels for some regions in the global north, significant drying “is observed in many regions in the global south”.
Similarly, a world geoengineered to 1.5C would see extreme nighttime heat in some tropical regions that is more severe than in a 2C world with no geoengineering, Hwong added.
In short, she said, “this implies the risk of creating winners and losers” under solar geoengineering and “raises concerns about equity and accountability that need to be considered”.
After describing how overshoot features in the outlines of the forthcoming AR7 reports in his opening speech, Prof Skea told Carbon Brief that he expects a “surge of papers” on overshoot in time to be included.
But it was important to emphasise that a “lot of the science that people have been carrying out is relevant within or without an overshoot”, he added:
“At points in the future, we are not going to know whether we’re in an overshoot world or just a high-emissions world, for example. So a lot of the climate research that’s been done is relevant regardless of overshoot. But overshoot is a new kind of dimension because of this issue of focus on 1.5C and concerns about its viability.”
Adaptation
The implications of overshoot temperature pathways for efforts to prepare cities, countries and citizens for the impacts of climate change remains an under-researched field.
Speaking in a plenary, Prof Kristie Ebi – a professor at the University of Washington’s Center for Health and the Global Environment – described research into adaptation and overshoot as “nascent”. However, she stressed that preparing society for the impacts associated with overshoot pathways was as important as bringing down emissions.
She told Carbon Brief that there were “all kinds of questions” about how to approach “effective” adaptation under an overshoot pathway, explaining:
“At the moment, adaptation is primarily assuming a continual increase in global mean surface temperature. If there is going to be a peak – and, of course, we don’t know what that peak is – then how do you start planning? Do you change your planning? There are places, for instance when thinking about hard infrastructure, [where overshoot] may result in a change in your plan.”
IIASA’s Schleussner told Carbon Brief that the scientific community was only just “beginning to appreciate” the need to understand and “quantify” the implications of different overshoot pathways on adaptation.
In a parallel session, Dr Elisabeth Gilmore, associate professor in environmental engineering and public policy at Carleton University in Canada, made the case for overshoot modelling pathways to take greater account of political considerations.
“Not just, but especially, in situations of overshoot, we need to start thinking about this as much as a physical process as a socio-political process…If we don’t do this, we are really missing out on some key uncertainties.”
Current scenarios used in climate research – including the Shared Socioeconomic Pathways and Representative Concentration Pathways – are “a bit quiet” when it comes to thinking about governance, institutions and peace and conflict, Gilmore said. She added:
“Political institutions, legitimacy and social cohesion continue to shift over time and this is really going to shape how much we can mitigate, how much we adapt and especially how we would recover when adding in the dimension of overshoot.”
Gilmore argued that, from a social perspective, adaptation needs are greatest “before the peak” of temperature rise – because this is when society can build the resilience to “get to the other side”. She said:
“Orthodoxy in adaptation [research] that you always want to plan for the worst [in the context of adaptation, peak temperature rise]… But we don’t really know what this peak is going to be – and we know that the politics and the social systems are much more messy.”
Dr Marta Mastropietro, a researcher at Politecnico di Milano in Italy, presented the preliminary results of a study that used emulators – simple climate models – to explore how human development might be impacted under low, medium and high overshoot pathways.
Mastropietro noted how, under all overshoot scenarios studied, both the drop to the human development index (HDI) – an index which incorporates health, knowledge and standard of living – and uncertainty increases as the peak temperature increases.
However, she said “the most important takeaway” from the preliminary results was around society’s constrained ability to recover from damage.
“This percentage of damages that are absorbed is always less than 50%. So, even in the most optimistic scenarios of overshoot, we will not be able to reabsorb these damages, not even half of them. And this is considering a damage function which does not consider irreversible impacts like sea level rise.”
Meanwhile, Dr Inês Gomes Marques from the University of Lisboa in Portugal, shared the results of an as-yet-unpublished study investigating whether the Lisbon metropolitan area holds enough public spaces to offer heatwave relief to the population under overshoot scenarios. The 1,900 “climate refugia” counted by researchers included schools, museums and churches.
Marques noted that most of the population were found to be within one kilometre of a “climate refugia” – but noted that “nuances” would need to be added to the analysis, including a function which considers the limited mobility of older citizens.
She explained that the researchers were aiming to “establish a framework” for this type of analysis that would be relevant to both the science community and municipalities tasked with adaptation. She added:
“The main point is that we need to think about this now, because we will face some big problems if we don’t”.
Legal implications and loss and damage
Significant attention was given throughout the conference to the legal considerations of the breach of – and impetus to return to – the Paris Agreement’s 1.5C warming limit.
This included discussions about how the international legal frameworks should be updated for an “overshoot” world where countries would need to pursue “net-negative” strategies to bring temperatures down to 1.5C.
There were also discussions around governance of geoengineering technologies and the fairness and justice considerations that arise from the real-world impacts of breached targets.
The conference was being held just months after the ICJ’s advisory decision that limiting temperature increase to 1.5C should be considered countries’ “primary temperature goal”.
IIASA’s Shleussner told Carbon Brief that the decision provided “clarity” that countries had a “clear obligation to bring warming back to 1.5C”. He added:
“We may fail to pursue it from below, but it doesn’t relieve us from the obligation to then pursue it from above.”
Prof Lavanya Rajamani, professor of international environmental law at the University of Oxford, insisted that “1.5C was very much alive and well in the legal world”, but noted there were “very significant limits” to what could be achieved through the UN Framework Convention for Climate Change (UNFCCC) – the global treaty for coordinating the response to climate change – both today and in the future.
Summarising discussions around how countries can be pushed to deliver the “highest possible ambition” in future climate plans submitted to the UN, Rajamani urged delegates to be “tempered in [its] expectations of what we’re going to get from the international regime”. She added:
“Changing the narratives and practices at the national level are far more likely to filter up to the international level than trying to do it from a top-down perspective.”
In a parallel session, Prof Christina Voigt, a professor of international law at the University of Oslo, pointed out that overshoot would require countries to aspire beyond “net-zero emissions” as “the end climate goal” in national plans.
Stabilising emissions at “net-zero” by mid-century would result in warming above 1.5C, she explained, whereas “net-negative” emissions are required to deliver overshoot pathways that return temperatures to below the Paris Agreement’s aspirational limit. She continued:
“We will need frontrunners. Leaders, states, regions would need to start considering negative-emission benchmarks in their climate policies and laws from around mid-century. There will be an expectation that developed country parties take the lead and explore this ‘negativity territory’.”
Voigt added that it was “critical” that nations at the UNFCCC create a “shared understanding” that 1.5C remains the “core target” for nations to aim for, even after it has been exceeded. One possible place for such discussions could be at the 2028 global stocktake, she noted.
She said there would need to be more regulation to scale up CDR in a way that addresses “environmental and social challenges” and an effort to “recalibrate policies and measures” – including around carbon markets – to deliver net-negative outcomes.
In a presentation exploring governance of solar radiation management (SRM), Ewan White, a DPhil student in environmental law at the University of Oxford, said the ICJ’s recent advisory opinion could be interpreted to be “both for and against” solar geoengineering.
Countries tasked with drawing up global rules around SRM in an overshoot world would need to take a “holistic approach to environmental law”, White said. In his view, this should take into account international legal obligations beyond the Paris Agreement and consider issues of intergenerational equity, biodiversity protection and nations’ duty to cooperate.
Dr Shonali Pachauri, research group leader at IIASA, provided an overview of the equity and justice implications that might arise in an overshoot world.
First, she said that delays to emissions reductions today are “shifting the burden” to future generations and “others within this generation” – increasing the need for “corrective justice” and potential loss-and-damage payments.
Second, she said that adaptation efforts would need to increase – which, in turn, would “threaten mitigation ambition” given “constrained decision-making”.
Finally, she pointed to resource consumption issues that might arise in a world of overshoot:
“The different technologies that one might use for CDR often depend on the use of land, water, other materials – and this, of course, then means competing with many other uses [of resources].”
A separate stream focused on loss and damage. Session chair Dr Sindra Sharma, international policy lead at the Pacific Islands Climate Action Network, noted that the concept of loss and damage was “fundamentally transformed” by overshoot – adding there were “deep issues of justice and equity”.
However, Sharma said that the literature on loss and damage “has not yet deeply engaged with the specific concept of overshoot” despite it being “an important, interconnected issue”.
Sessions on loss and damage explored the existence of “hard social limits” under future overshoot scenarios, insurance and the need to bring more factors into assessments of habitability, including biophysical and social-economic constraints.
Communication challenges and next steps
At the conference, scientists and legal experts collaborated on a series of statements that summarised discussions at the conference – one for each research theme and an overarching umbrella statement.
IIASA’s Schleussner told Carbon Brief that the statements represented a “key outcome of the conference” that could provide a “framework” to guide future research.
Nevertheless, he noted that statements are a “work in progress” and set to be “further refined” following feedback from experts not able to attend the conference.
At the time of going to press, the overarching conference statement read as follows:
“Global warming above 1.5C will increase irreversible and unacceptable losses and damages to people, societies and the environment.
“It is imperative to minimise both the maximum warming and duration of overshoot above 1.5C to reduce additional risks of human rights violations and causing irreversible social, ecological and Earth system changes including transgressing tipping points.
“This is required by international law and possible by removing CO2 from the atmosphere and further reducing remaining greenhouse emissions.”
Conference organisers also pointed delegates to an open call for research on “pathways and consequences of overshoot” in the journal Environmental Research Letters. The special issue will be guest edited by a number of scientists who played a key role in the conference.
Meanwhile, communications experts at the conference discussed the challenges inherent in conveying overshoot science to non-experts, noting potential confusion around the word “overshoot” and the difficulties in explaining that the 1.5C limit, while breached, was still a goal.
Holly Simpkin, communications manager at the Potsdam Institute for Climate Impact Research, urged caution when communicating overshoot science to the general public:
“I don’t know whether ‘overshoot’ is an effective communication framing. It is an important scientific question, but when it comes to near-term action and the requirements that an ambitious overshoot pathway would ask of us, emissions are what are in our control.
“We could spend 10 more years defining this and, actually, it’s quite complex…I think it’s better to be honest about that and to try to be more simple in that frame of communication, knowing that this community is doing a wealth of work that provides a technical basis for those discussions.”
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Overshoot: Exploring the implications of meeting 1.5C climate goal ‘from above’
Greenhouse Gases
Analysis: Fossil-fuel CO2 emissions to set new record in 2025, as land sink ‘recovers’
Carbon dioxide (CO2) emissions from fossil fuels and cement will rise around 1.1% in 2025, reaching a record 38.1bn tonnes of CO2 (GtCO2), according to the latest figures from the Global Carbon Project.
However, falling land-use emissions means that global CO2 emissions in 2025 will remain relatively unchanged compared to 2024 levels.
The 20th edition of the annual Global Carbon Budget report, published today, also finds that the land carbon sink – the portion of human-caused CO2 emissions absorbed by plants and soils – appears to have recovered to its pre-El Niño strength after two unusually weak years.
However, research published alongside the report by the same team also suggests that climate change has caused a long-term decline in land and ocean carbon sinks, with sinks being about 15% weaker over the past decade than they would have been without climate impacts.
The study, published in Nature, finds that the decline of carbon sinks has contributed about 8% to the rise in atmospheric CO2 concentration since 1960.
The 2025 Global Carbon Budget report also estimates that:
- Emissions in China and India are projected to grow much less in 2025 compared to the past decade, while emissions in the US and EU are projected to grow this year after years of decline.
- Global CO2 emissions from land-use change are expected to decrease by nearly 10% in 2025, driven by reductions in deforestation and forest degradation in South America.
- Total CO2 emissions – fossil and land use – have grown more slowly over the past decade (0.3% per year on average) compared to the previous decade (1.9% per year).
- The remaining carbon budget to limit global warming to 1.5C is virtually exhausted and is equivalent to only four years of current emissions. Carbon budgets to limit warming to 1.7C and 2C would similarly be used up in 12 and 25 years, respectively.
- The concentration of CO2 in the atmosphere is set to reach 425.7 parts per million (ppm) in 2025, 2.3ppm above 2023 and 52% above pre-industrial levels.
(For detailed coverage of previous editions of the report, see Carbon Brief’s coverage for 2024, 2023 and 2022.)
Global emissions remain flat
The Global Carbon Budget (GCB) finds that total global CO2 emissions in 2025 – including those from fossil fuels and land use – are projected to remain approximately flat at 42.2GtCO2, falling by a negligible -0.04% compared to last year.
This means 2025 is effectively tied with 2024 as the highest global CO2 emissions on record.
Flat total CO2 emissions in 2025 reflect a combination of continued rising emissions from fossil fuel and industry and declining emissions from land-use change. Fossil CO2 emissions rose 1.1% to 38.1GtCO2, while land-use emissions declined by -9.8% to 4.1GtCO2 (albeit with large uncertainties).
The figure below shows the 2025 global CO2 emissions update (red solid line) alongside 2024 (dark blue dotted), 2023 (mid blue dotted) 2022 (light blue dotted), 2021 (light grey dotted) and 2020 (dark grey dotted). The shaded area indicates the uncertainty around the new 2025 budget.
(Each year, the GCB is updated to include the latest data as well as improvements to modelling sources and sinks, resulting in some year-to-year revisions to the historical record.)
The 2025 figures are notably higher than those in the prior five GCB reports, reflecting an upward revision in historical land-use emissions. (This is discussed in more detail in the land-use emissions section below.)
Total global CO2 emissions have notably flattened in the past decade (2014-25), growing at only 0.3% per year compared to the 1.9% rate of growth during the prior decade (2004-13) and the longer-term average growth rate of 1.6% over 1959-2014.
This apparent flattening is due to declining land-use emissions compensating for continued – but slow – increases in fossil CO2 emissions. Fossil emissions grew around 0.2GtCO2 per year over the past decade, while land-use emissions decreased by a comparable amount.
However, despite the emissions plateau, there is still no sign of the rapid and deep decrease in CO2 emissions needed to reach net-zero and stabilise global temperatures in-line with the Paris Agreement temperature goal.
If global emissions remain at current levels, the remaining carbon budget to limit warming to 1.5C (with a 50% chance) will be rapidly exhausted.
(The carbon budget is the total amount of CO2 that scientists estimate can be emitted if warming is to be kept below a particular temperature threshold. Earlier this year, the Indicators of Global Climate Change report estimated the remaining carbon budget had declined by three-quarters between the start of 2020 and the start of 2025.)
With human-caused global warming sitting at around 1.36C above pre-industrial levels in 2024, the remaining budget for 1.5C is 170GtCO2, equivalent to four years of current emissions.
The GCB report finds that the remaining carbon budgets to limit warming to 1.7C and 2C have been reduced to 525GtCO2 (12 years at current emissions levels) and 1,055GtCO2 (25 years), respectively.
Global fossil CO2 emissions also grew more slowly in the past decade (0.8% per year) compared to the previous decade (2.1%). This was driven by the continued decarbonisation of energy systems – including a shift from burning coal to gas and replacing fossil fuels with renewables – as well as slightly weaker global economic growth during the past decade.
The figure below breaks down global emissions (dark blue line) in the 2025 budget into fossil (mid blue) and land-use (light blue) components. Fossil CO2 emissions represent the bulk of total global emissions in recent years, accounting for approximately 90% of emissions in 2025 (compared to 10% for land use). This represents a large change from the first half of the 20th century, when land-use emissions were approximately the same as fossil emissions.
Global fossil emissions include CO2 emitted from burning coal, oil and gas, as well as the production of cement. However, to determine total fossil emissions, the Global Carbon Budget also subtracts the cement carbonation sink – CO2 slowly absorbed by cement once it is exposed to the air – from fossil emissions.
Global emissions can also be expressed on a per-capita basis, as shown in the figure below.
While it is ultimately total global emissions that matter for the Earth’s climate – and a global per-capita figure glosses over a lot of variation among, and within, countries – it is noteworthy that global per-capita fossil emissions peaked in 2012 and have been slightly declining in the years since.
Land-use emissions continue downward trend
Global land-use emissions stem from deforestation, forest degradation, loss of peatlands and harvesting trees for wood. They averaged around 5.0GtCO2 over the past decade (2015-24) and the Global Carbon Budget provides an initial projection for 2025 of 4.1GtCO2.
This represents a 0.5GtCO2 decrease in land-use emissions relative to 2024. The GCB report suggests that this was largely driven by a combination of reductions in deforestation and forest degradation in South America and by the end of the dry 2023-24 El Niño conditions.
Overall, land-use emissions have decreased by around 32% compared to their average in the 2000s, with a particularly large drop in the past decade. This decline is statistically significant and is due both to decreasing deforestation and increasing levels of reforestation and afforestation globally.
Three countries – Brazil, Indonesia and the Democratic Republic of the Congo (DRC) – collectively contribute approximately 57% of the global land-use emissions. In the past, China has been a meaningful contributor to land-use emissions, but in recent years its land-use emissions have turned net-negative as more trees have been planted than cut down.
The figure below shows changes in emissions over time in these countries, as well as land-use emissions in the rest of the world (grey).
Historical land-use emissions have been revised upward in the 2025 GCB report compared to prior estimates. This reflects a combination of two factors:
- The discontinuation of one of the four bookkeeping models that GCB has historically relied on for land-use emissions estimates. This model tended to show lower land-use emissions than the others.
- The inclusion of the impacts from CO2 fertilisation on global biomass densities. Because forests have higher biomass densities now than in the past, due to increasing CO2, this tends to increase the estimate of land-use emissions for recent years.
Fossil-fuel CO2 hits record highs
Global emissions of fossil CO2 – including coal, oil, gas and cement – increased by around 1.1% in 2025, relative to 2024, with an uncertainty range of 0.2-2.2%. This represents a new record high and surpasses the prior record set in 2024.
The figure below shows global CO2 emissions from fossil fuels, divided into emissions from major emitting countries including China (dark blue shading), the US (mid blue), the EU (light blue), India (light blue) and the remainder of the world (grey).
China represents 32% of global CO2 emissions today. Its 2025 emissions are projected to increase by a relatively small 0.4% (with an uncertainty range of -0.9% to 2%), driven by a small rise in emissions from coal (0.3%), a modest rise in gas (1.3%) and a larger rise in oil (2.1%).
Given the uncertainty range, a decrease in Chinese emissions is also a possibility, but this will not be confirmed until the full 2025 data is available.
Similarly, recent analysis for Carbon Brief found that China’s emissions were “finely balanced between a small fall or rise” in 2025. However, it said that a drop in the full-year total became more likely after a 3% decline in September. (The Global Carbon Project estimates are based on data covering January through to August, which point towards a small rise in 2025.)
Whether China’s emissions see small rise or fall in 2025, the outcome will be due to moderate growth in energy consumption combined with an extraordinary growth in renewable power generation. This would represent the second year in a row where Chinese emissions growth was well below the average rate over the past decade.
The US represents 13% of global emissions and emissions in 2025 are projected to increase by 1.9% (-0.2 to +4.1%) compared with 2024. This marks a reversal from recent trends in declining CO2 emissions.
The projected growth of emissions in the US is likely driven by a combination of three factors: a colder start to the year after a mild 2024, which led to greater heating requirements, higher gas prices, which led to more coal being used in power generation, as well as an increase in total demand for electricity.
US emissions from coal are expected to increase by a substantial 7.5% in 2025, emissions from both oil and gas by a more modest 1.1% and emissions from cement to fall by -8.0%.
While policies enacted by the current US administration may increase CO2 emissions going forward, their impact on national emissions levels in 2025 were likely relatively modest compared to other factors.
India represents 8% of global emissions. In 2025, its emissions are projected to increase by 1.4% (-0.3% to +3.1%) on 2024 levels, significantly below recent trends.
An early monsoon with the highest-ever May rainfall substantially reduced cooling requirements in May and June, the hottest months of the year. Strong growth or renewables – particularly solar – has also helped limit the growth of Indian emissions.
Indian emissions from coal are expected to grow 1.7%, with oil growing 0.1%, gas shrinking by -6.4% and cement growing by 9.9%.
The EU represents 6% of global emissions. Its emissions are projected to increase by 0.4% in 2025, with an uncertainty range of -2.1 to +2.8%. This represents a divergence from a past decline in emissions (albeit with large uncertainties).
EU emissions from coal are expected to decline by -0.3%, whereas emissions from oil and gas are projected to increase by 0.6% and 0.9%, respectively. Cement emissions are expected to fall by -4.1%.
The increase in EU emissions is in part from weather-related low hydropower and wind generation which – despite increases in solar – have led to an increase in electricity generation from gas. In addition, a relatively cold February led to increased use of natural gas for space heating.
International aviation and shipping (included in the “rest of world” in the chart above) are responsible for 3% of global emissions. They are projected to increase by 6.8% for aviation, but remain flat for international shipping. This year will be the first time that aviation emissions have exceeded pre-Covid levels.
The rest of the world (excluding aviation) represents 38% of global emissions. Emissions are expected to grow by 1.1% in 2025 (ranging from -1.1% to +3.3%), with increases in emissions from coal (1%), oil (0.5%), gas (1.8%) and cement (2.4%).
The total emissions for each year over 2022-25, as well as the countries and regions that were responsible for the changes in absolute emissions, are shown in the figure below.
Annual emissions for 2022, 2023, 2024 and estimates for 2025 are shown by the black bars. The smaller bars show the change in emissions between each set of years, broken down by country or region – the US (dark blue), EU (mid blue), China (light blue), India (pale blue) and the rest of the world (grey). Negative values show reductions in emissions, while positive values reflect emission increases.
The US represented a large part of the rise in global fossil-fuel emissions in 2025. US emissions increases over 2024-25 contributed about 40% of the total global increase – more than the EU, China and India contributions combined.
The Global Carbon Project notes that emissions have declined over the past decade (2015-24) in 35 nations, which collectively account for 27% of global emissions. This is up from 18 countries during the prior decade (2005-14).
The decrease in emissions in those countries comes despite continued domestic economic growth and represents a long-term “decoupling” of CO2 emissions and the economy.
The carbon intensity of energy has consistently decreased over the past decade in China, the US, the EU – and, to a lesser extent, globally.
However, peaking CO2 emissions requires that the rate of decarbonisation exceeds the growth in energy demand. This has happened in some regions, including the US and EU, but not yet globally.
Modest growth in emissions from coal, oil, gas and cement
Global fossil-fuel emissions primarily result from the combustion of coal, oil and gas.
In 2025, coal is responsible for more emissions than any other fossil fuel, representing approximately 42% of global fossil-fuel CO2 emissions. Oil is the second largest contributor at 33% of fossil CO2, while gas comes in at 21%.
The production of cement is responsible for around 3.8% of global emissions, but this is reduced to 1.9% once the carbonation sink – the drawdown of atmospheric CO2 by concrete – is taken into account.
These percentages reflect both the amount of each fossil fuel consumed globally, but also differences in CO2 intensities. Coal results in the most CO2 emitted per unit of heat or energy produced, followed by oil and gas.
The figure below shows global CO2 emissions from different fuels over time, covering coal (dark blue), oil (mid blue) and gas (light blue), as well as cement production (pale blue) and other sources (grey).
While coal emissions increased rapidly in the mid-2000s, they have largely flattened since 2013. However, coal use increased significantly in 2021 and then more modestly in the subsequent four years.
Global emissions from coal increased by 0.8% in 2025 compared to 2024, while oil emissions increased 1.0% and gas emissions increased by 1.3%.
Despite setting a new record this year, global coal use is only 6% above 2013 levels – a full 13 years ago. By contrast, during the 2000s, global coal use grew at a rate of around 4% every single year.
The figure below shows the total emissions for each year over 2022-25 (black bars), as well as the absolute change in emissions for each fuel between years.
Global oil emissions were suppressed for a few years after the 2020, but rebounded to pre-pandemic levels as of 2024 and have continued to grow in 2025.
This reflects that, despite falling sales of internal combustion engine vehicles, not enough electric vehicles (EVs) have yet been sold to result in peak oil demand.
The global carbon budget
Every year, the Global Carbon Project provides an estimate of the overall “global carbon budget”. This is based on estimates of the release of CO2 through human activity and its uptake by the oceans and land, with the remainder adding to atmospheric concentrations of the gas.
(This differs from the commonly used term “remaining carbon budget”, which refers to the amount of CO2 that can be released while keeping warming below global limits of 1.5 or 2C.)
The most recent budget, including estimated values for 2025, is shown in the figure below.
Values above zero represent sources of CO2 – from fossil fuels and industry (dark blue shading) and land use (mid blue) – while values below zero represent carbon sinks that remove CO2 from the atmosphere. Any CO2 emissions that are not absorbed by the oceans (light grey) or land vegetation (mid grey) accumulate in the atmosphere (dark grey). In addition, a dashed black line is shown to represent the expected sum of sinks based on estimated emissions.
Over the past decade (2015-24), the world’s oceans have taken up approximately 29% of total human-caused emissions, or around 11.8GtCO2 per year.
The ocean CO2 sink has been relatively flat since 2014 after growing rapidly over the prior decades, reflecting the flattening of global emissions during that period.
This estimate for carbon sinks has been revised up from 26% in prior versions of the GCB, reflecting a major update to carbon budgets driven by new data and modelling of carbon sink behavior.
The land sink takes up around 21% of global emissions, or 8.7GtCO2 per year on average over the past decade – discussed in more detail in the section below. This is down from 29% in prior budgets.
The atmosphere continues to accumulate the bulk of human-caused CO2 emissions, with about 49% going into the atmosphere on average over the past decade – a rate of 20.4GtCO2 per year.
The growth rate of atmospheric CO2 in 2025 is expected to be around 2.3ppm, which is a bit below the decadal average rate of 2.6ppm over the past decade (2015-24). This is well below the record-setting rise of 3.7ppm in 2024, which was primarily driven by the effect of the 2023-24 El Niño conditions weakening the land sink.
Atmospheric CO2 concentrations are set to reach an annual average of 425.7ppm in 2025, representing an increase of 52% above pre-industrial levels of 280ppm.
There remains an unusual imbalance in the carbon budget in 2024, where the sum of the sinks is notably larger than estimated emissions. This can be seen in the figure above, where the dashed line is below the shaded area.
Budget imbalances are not unprecedented – there are large uncertainties in both emissions data and sink estimates. But the rise in the amount of CO2 accumulating in the atmosphere in 2024 is larger than would be expected based on emissions.
There are a number of potential explanations for this 2024 imbalance. The land cover data for 2024 is not yet complete and it is possible that some fire emissions data might be missing from the record. This might result in either higher land-use emissions or lower land sinks than currently estimated.
Alternatively, it could be due to the CO2 growth rate – captured by surface stations managed by the US National Atmospheric and Oceanic Administration (NOAA) – being slightly high. CO2 records for 2024 from these stations are higher than those obtained from satellite-based sensors, though it remains unclear which provides the most accurate measurement.
A declining, but not collapsing, land sink
After an usually weak land carbon sink in 2023, there were a number of media articles about its potential collapse.
For example, in October 2024, the Guardian wrote that “the sudden collapse of carbon sinks was not factored into climate models – and could rapidly accelerate global heating”.
The truth is a bit more complicated. While the impending collapse of the land carbon sink has been greatly exaggerated, there is growing evidence of a long-term weakening of both the land and ocean carbon sinks due to human activity.
And while the land sink has recovered to its pre-El Niño strength in 2025, aided by relatively low global fire CO2 emissions, it will continue to gradually weaken as global temperatures rise. This is not unexpected – scientists have long foreseen a weaker carbon sink in a warmer world.
A weaker land sink will contribute to higher global temperatures in the future as more CO2 emissions from burning fossil fuels and land use change will accumulate in the atmosphere.
The figure below shows the percentage of human emissions absorbed by the land sink in every year since 1959, with a recovery upwards in 2025 after two relatively low years.
In a study published in Nature alongside the release of the 2025 Global Carbon Budget, the same team of researchers provide a detailed estimate of exactly how the land and ocean sinks have changed as a result of human activity.
The research finds that the land and ocean sinks are 25% smaller and 7% smaller, respectively, than they would have been without the effects of climate change over 2015-24.
This amounts to a nearly 20% reduction in the efficacy of current global carbon sinks – that is, both the land and ocean – and a 15% reduction compared to how large they would be without the effects of climate change.
The figure below, from the new paper, shows the impact of climate change on the ocean sink (blue), the land sink (green) and atmospheric CO2 concentrations (grey) since 1960.
The weakening of carbon sinks due to human activity has led to an increase of atmospheric CO2 of more than 8ppm since 1960. The combined effects of climate change and deforestation have turned tropical forests in south-east Asia and in large parts of South America from CO2 sinks to sources.
And these sinks will likely continue to weaken as long as atmospheric CO2 concentrations continue to rise and the world continues to warm. There are a wide range of estimates of carbon cycle feedbacks among climate models, but a large carbon cycle feedback could result in a few tenths of a degree of future warming.
The post Analysis: Fossil-fuel CO2 emissions to set new record in 2025, as land sink ‘recovers’ appeared first on Carbon Brief.
Analysis: Fossil-fuel CO2 emissions to set new record in 2025, as land sink ‘recovers’
Greenhouse Gases
IEA: Fossil-fuel use will peak before 2030 – unless ‘stated policies’ are abandoned
The world’s fossil-fuel use is still on track to peak before 2030, despite a surge in political support for coal, oil and gas, according to data from the International Energy Agency (IEA).
The IEA’s latest World Energy Outlook 2025, published during the opening days of the COP30 climate summit in Brazil, shows coal at or close to a peak, with oil set to follow around 2030 and gas by 2035, based on the stated policy intentions of the world’s governments.
Under the same assumptions, the IEA says that clean-energy use will surge, as nuclear power rises 39% by 2035, solar by 344% and wind by 178%.
Still, the outlook has some notable shifts since last year, with coal use revised up by around 6% in the near term, oil seeing a shallower post-peak decline and gas plateauing at higher levels.
This means that the IEA expects global warming to reach 2.5C this century if “stated policies” are implemented as planned, up marginally from 2.4C in last year’s outlook.
In addition, after pressure from the Trump administration in the US, the IEA has resurrected its “current policies scenario”, which – effectively – assumes that governments around the world abandon their stated intentions and only policies already set in legislation are continued.
If this were to happen, the IEA warns, global warming would reach 2.9C by 2100, as oil and gas demand would continue to rise and the decline in coal use would proceed at a slower rate.
This year’s outlook also includes a pathway that limits warming to 1.5C in 2100, but says that this would only be possible after a period of “overshoot”, where temperature rise peaks at 1.65C.
The IEA will publish its “announced pledges scenario” at a later date, to illustrate the impact of new national climate pledges being implemented on time and in full.
(See Carbon Brief’s coverage of previous IEA world energy outlooks from 2024, 2023, 2022, 2021, 2020, 2019, 2018, 2017, 2016 and 2015.)
World energy outlook
The IEA’s annual World Energy Outlook (WEO) is published every autumn. It is regarded as one of the most influential annual contributions to the understanding of energy and emissions trends.
The outlook explores a range of scenarios, representing different possible futures for the global energy system. These are developed using the IEA’s “global energy and climate model”.
The latest report stresses that “none of [these scenarios] should be regarded as a forecast”.
However, this year’s outlook marks a major shift in emphasis between the scenarios – and it reintroduces a pathway where oil and gas demand continues to rise for many decades.
This pathway is named the “current policies scenario” (CPS), which assumes that governments abandon their planned policies, leaving only those that are already set in legislation.
If the world followed this path, then global temperatures would reach 2.9C above pre-industrial levels by 2100 and would be “set to keep rising from there”, the IEA says.
The CPS was part of the annual outlook until 2020, when the IEA said that it was “difficult to imagine” such a pathway “prevailing in today’s circumstances”.
It has been resurrected following heavy pressure from the US, which is a major funder of the IEA that accounts for 14% of the agency’s budget.
For example, in July Politico reported “a ratcheted-up US pressure campaign” and “months of public frustrations with the IEA from top Trump administration officials”. It noted:
“Some Republicans say the IEA has discouraged investment in fossil fuels by publishing analyses that show near-term peaks in global demand for oil and gas.”
The CPS is the first scenario to be discussed in detail in the report, appearing in chapter three. The CPS similarly appears first in Annex A, the data tables for the report.
The second scenario is the “stated policies scenario” (STEPS), featured in chapter four of this year’s outlook. Here, the outlook also includes policies that governments say they intend to bring forward and that the IEA judges as likely to be implemented in practice.
In this world, global warming would reach 2.5C by 2100 – up marginally from the 2.4C expected in the 2024 edition of the outlook.
Beyond the STEPS and the CPS, the outlook includes two further scenarios.
One is the “net-zero emissions by 2050” (NZE) scenario, which illustrates how the world’s energy system would need to change in order to limit warming in 2100 to 1.5C.
The NZE was first floated in the 2020 edition of the report and was then formally featured in 2021.
The report notes that, unlike in previous editions, this scenario would see warming peak at more than 1.6C above pre-industrial temperatures, before returning to 1.5C by the end of the century.
This means it would include a high level of temporary “overshoot” of the 1.5C target. The IEA explains that this results from the “reality of persistently high emissions in recent years”. It adds:
“In addition to very rapid progress with the transformation of the energy sector, bringing the temperature rise back down below 1.5C by 2100 also requires widespread deployment of CO2 removal technologies that are currently unproven at large scale.”
Finally, the outlook includes a new scenario where everyone in the world is able to gain access to electricity by 2035 and to clean cooking by 2040, named “ACCESS”.
While the STEPS appears second in the running order of the report, it is mentioned slightly more frequently than the CPS, as shown in the figure below. The CPS is a close second, however, whereas the IEA’s 1.5C pathway (NZE) receives a declining level of attention.
US critics of the IEA have presented its stated policies scenario as “disconnected from reality”, in contrast to what they describe as the “likely scenario” of “business as usual”.
Yet the current policies scenario is far from a “business-as-usual” pathway. The IEA says this explicitly in an article published ahead of the outlook:
“The CPS might seem like a ‘business-as-usual’ scenario, but this terminology can be misleading in an energy system where new technologies are already being deployed at scale, underpinned by robust economics and mature, existing policy frameworks. In these areas, ‘business as usual’ would imply continuing the current process of change and, in some cases, accelerating it.”
In order to create the current policies scenario, where oil and gas use continues to surge into the future, the IEA therefore has to make more pessimistic assumptions about barriers to the uptake of new technologies and about the willingness of governments to row back on their plans. It says:
“The CPS…builds on a narrow reading of today’s policy settings…assuming no change, even where governments have indicated their intention to do so.”
This is not a scenario of “business as usual”. Instead, it is a scenario where countries around the world follow US president Donald Trump in dismantling their plans to shift away from fossil fuels.
More specifically, the current policies scenario assumes that countries around the world renege on their policy commitments and fail to honour their climate pledges.
For example, it assumes that Japan and South Korea fail to implement their latest national electricity plans, that China fails to continue its power-market reforms and abandons its provincial targets for clean power, that EU countries fail to meet their coal phase-out pledges and that US states such as California fail to extend their clean-energy targets.
Similarly, it assumes that Brazil, Turkey and India fail to implement their greenhouse gas emissions trading schemes (ETS) as planned and that China fails to expand its ETS to other industries.
The scenario also assumes that the EU, China, India, Australia, Japan and many others fail to extend or continue strengthening regulations on the energy efficiency of buildings and appliances, as well as those relating to the fuel-economy standards for new vehicles.
In contrast to the portrayal of the stated policies scenario as blindly assuming that all pledges will be met, the IEA notes that it does not give a free pass to aspirational targets. It says:
“[T]argets are not automatically assumed to be met; the prospects and timing for their realisation are subject to an assessment of relevant market, infrastructure and financial constraints…[L]ike the CPS, the STEPS does not assume that aspirational goals, such as those included in the Paris Agreement, are achieved.”
Only in the “announced pledges scenario” (APS) does the IEA assume that countries meet all of their climate pledges on time and full – regardless of how credible they are.
The APS does not appear in this year’s report, presumably because many countries missed the deadlines to publish new climate pledges ahead of COP30.
The IEA says it will publish its APS, assessing the impact of the new pledges, “once there is a more complete picture of these commitments”.
Fossil-fuel peak
In recent years, there has been a significant shift in the IEA’s outlook for fossil fuels under the stated policies scenario, which it has described as “a mirror to the plans of today’s policymakers”.
In 2020, the agency said that prevailing policy conditions pointed towards a “structural” decline in global coal demand, but that it was too soon to declare a peak in oil or gas demand.
By 2021, it said global fossil-fuel use could peak as soon as 2025, but only if all countries got on track to meet their climate goals. Under stated policies, it expected fossil-fuel use to hit a plateau from the late 2020s onwards, declining only marginally by 2050.
There was a dramatic change in 2022, when it said that Russia’s invasion of Ukraine and the resulting global energy crisis had “turbo-charged” the shift away from fossil fuels.
As a result, it said at the time that it expected a peak in demand for each of the fossil fuels. Coal “within a few years”, oil “in the mid-2030s” and gas ”by the end of the decade”.
This outlook sharpened further in 2023 and, by 2024, it was saying that each of the fossil fuels would see a peak in global demand before 2030.
This year’s report notes that “some formal country-level [climate] commitments have waned”, pointing to the withdrawal of the US from the Paris Agreement.
The report says the “new direction” in the US is among “major new policies” in 48 countries. The other changes it lists include Brazil’s “energy transition acceleration programme”, Japan’s new plan for 2040 and the EU’s recently adopted 2040 climate target.
Overall, the IEA data still points to peaks in demand for coal, oil and gas under the stated policies scenario, as shown in the figure below.
Alongside this there is a surge in clean technologies, with renewables overtaking oil to become the world’s largest source of energy – not just electricity – by the early 2040s.
In this year’s outlook under stated policies, the IEA sees global coal demand as already being at – or very close to – a definitive peak, as the chart above shows.
Coal then enters a structural decline, where demand for the fuel is displaced by cheaper alternatives, particularly renewable sources of electricity.
The IEA reiterates that the cost of solar, wind and batteries has respectively fallen by 90%, 70% and 90% since 2010, with further declines of 10-40% expected by 2035.
(The report notes that household energy spending would be lower under the more ambitious NZE scenario than under stated policies, despite the need for greater investment.)
However, this year’s outlook has coal use in 2030 coming in some 6% higher than expected last year, although it ultimately declines to similar levels by 2050.
For oil, the agency’s data still points to a peak in demand this decade, as electric vehicles (EVs) and more efficient combustion engines erode the need for the fuel in road transport.
While this sees oil demand in 2030 reaching similar levels to what the IEA expected last year, the post-peak decline is slightly less marked in the latest outlook, ending some 5% higher in 2050.
The biggest shift compared with last year is for gas, where the IEA suggests that global demand will keep rising until 2035, rather than peaking by 2030.
Still, the outlook has gas demand in 2030 being only 7% higher than expected last year. It notes:
“Long-term natural gas demand growth is kept lower than in recent decades by the expanding deployment of renewables, efficiency gains and electrification of end-uses.”
In terms of clean energy, the outlook sees nuclear power output growing to 39% above 2024 levels by 2035 and doubling by 2050. Solar grows nearly four-fold by 2035 and nearly nine-fold by 2050, while wind power nearly triples and quadruples over the same periods.
Notably, the IEA sees strong growth of clean-energy technologies, even in the current policies scenario. Here, renewables would still become the world’s largest energy source before 2050.
This is despite the severe headwinds assumed in this scenario, including EVs never increasing from their current low share of sales in India or the US.
The CPS would see oil and gas use continuing to rise, with demand for oil reaching 11% above current levels by 2050 and gas climbing 31%, even as renewables nearly triple.
This means that coal use would still decline, falling to a fifth below current levels by 2050.
Finally, while the IEA considers the prospect of global coal demand continuing to rise rather than falling as expected, it gives this idea short shrift. It explains:
“A growth story for coal over the coming decades cannot entirely be ruled out but it would fly in the face of two crucial structural trends witnessed in recent years: the rise of renewable sources of power generation, and the shift in China away from an especially coal-intensive model of growth and infrastructure development. As such, sustained growth for coal demand appears highly unlikely.”
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IEA: Fossil-fuel use will peak before 2030 – unless ‘stated policies’ are abandoned
For the first time in the history of COP climate summits, the US – the world’s largest historical emitter – has not sent a delegation to the talks.
Back in January, newly inaugurated US president Donald Trump signed a letter to the UN to trigger the start of a US withdrawal from the Paris Agreement for a second time.
Although this process is not yet complete, the White House confirmed earlier this month that no “high-level officials” would be attending COP30 in Belém, Brazil.
The US joins Afghanistan, Myanmar and San Marino as the only countries not registering a delegation for the summit, according to Carbon Brief’s analysis of the provisional lists of delegates published by the United Nations Framework Convention on Climate Change (UNFCCC).
Despite these absences, more than 56,000 delegates have signed up to COP30, provisionally placing the summit as one of the largest in COP history.
This is despite the run-up to the negotiations being dogged by reports of a shortage of beds and “sky-high” accommodation costs.
Brazil even offered free cabins on cruise ships moored in Belém to delegations from low-income nations who were otherwise unable to attend.
According to the provisional figures, 193 countries, plus the European Union, have registered a delegation for the summit.
Unsurprisingly, the largest delegation comes from COP30 hosts Brazil, with 3,805 people registered.
This is followed, in order, by China, Nigeria, Indonesia and the Democratic Republic of the Congo.
This year also sees the largest number of “virtual” delegates, with more than 5,000 people signed up to attend the talks online.
Party delegations
With 56,118 delegates registered, COP30 is provisionally the second-largest COP in history, behind only COP28 in Dubai, which was attended by more than 80,000 people.
This is the provisional total, based on the delegates that have registered to be at the summit in person. At recent COPs, the final total is at least 10,000 lower, which would drop COP30 down to the fourth largest.
(The UNFCCC releases the final figures – based on participants collecting a physical badge at the venue – after the summit has closed.)
The chart below shows how the provisional figures for COP30 compare to the final totals in past COPs – going back to COP1 in Berlin in 1995.
The participant lists provided by the UNFCCC are divided between the different types of groups and organisations attending the summit. The largest group at COP30 is for delegates representing parties. These are nation states, plus the European Union, that have ratified the convention and play a full part in negotiations.
This group adds up to 11,519 delegates – the fourth largest behind the past three COPs.
(In keeping with recent COPs, the UNFCCC has published spreadsheets that name every single person that has registered for the summit – excluding support staff. Previously, COPs have typically included thousands of “overflow” participants in which countries and UN agencies could nominate delegates without their names appearing on their official lists.)
For consistency with Carbon Brief’s analysis of previous COPs, the above chart includes overflow delegates as a single group. However, the participant lists do divide the overflow delegates between parties and observer groups. Including the overflow numbers approximately doubles the total for party representatives to 23,509.
US no-show
Overall, of the 198 parties to the UNFCCC, 194 have registered delegations for COP30.
The most notable absentee is the US, which has been present at every other COP in history – even throughout Donald Trump’s first presidency.
On average, the US sends a delegation of around 100 people, typically making it one of the larger groups at the talks.
The absent parties – Afghanistan, Myanmar and San Marino – have been more sporadic attendees at past COPs.
Despite reports of a “logistical nightmare” hosting a COP summit in the Amazon, there has been no drop-off in the number of countries registering delegations for COP30.
In addition to hotel rooms and rental properties in Belém, beds have been made available on cruise ships, in converted shipping containers and in motels that Reuters primly described as being typically “aimed at amorous couples”.
Reports suggested that many developing nations considered scaling back their presence at COP30, with smaller delegations or attendees only coming for a few days.
While the average party delegation size of 59 (excluding overflows) is lower than the previous two COPs, it is similar to the average in COP26 in Glasgow and COP27 in Sharm el-Sheikh.
The map and table below present the delegation size – split between party and overflow badges – for all the countries registered for COP30. The darker the shading, the more delegates that country has signed up. Use the search box to find the data for a specific party.
The largest delegation comes from host country Brazil, with 3,805 people registered. China (789) and Nigeria (749) follow with the second- and third-largest, respectively.
Making up the rest of the top 10 are Indonesia (566), the Democratic Republic of the Congo (556), France (530), Chad (528), Australia (494), Tanzania (465) and Japan (461).
The UK comes someway down the list with a delegation of 210.
(It is worth noting that some countries – such as Brazil – allocate some of their party badges to NGOs, which can artificially inflate the size of their official delegation.)
The smallest delegation is the one person registered to represent Nicaragua. There are five delegations of two people (North Korea, Latvia, Liechtenstein, Saint Vincent and the Grenadines and Slovakia).
Ahead of COP30, Latvia's climate minister, told Reuters that the country had asked if its negotiators could dial into the summit by video call. However, Latvia does not appear to have registered any delegates to attend virtually.
In total, 40 parties registered virtual delegates. Party totals are all in single figures apart from the Philippines (31), Costa Rica (21) and Turkey (16).
Changing gender balance
The UNFCCC’s participant lists typically provide a title – such as Mr, Ms, Sr or Sra – for each registered delegate. In the past, this has allowed Carbon Brief to work out the balance of men to women in the delegations that each country has sent to a COP.
(This analysis always carries the caveat that the titles are designated by UNFCCC and not by Carbon Brief. In addition, Carbon Brief recognises that gender is not best categorised using a binary “man” or “woman” label and appreciates that the UNFCCC’s lists may not be wholly accurate.)
Overall, the COP30 provisional list suggests an average gender balance of party delegations of 57% men to 43% women.
As the chart below shows, this makes COP29 the most balanced COP in history. For consistency, the COP28, COP29 and COP30 figures only include those on party badges, not overflow ones.
(Note: Since COP28 last year, the UNFCCC has also used titles that do not indicate gender – such as Dr, Prof, Ambassador and Honourable. Therefore, for this analysis, these non-gendered titles – which make up 1% of all the people at COP30, for example – have not been included.)
There are four party delegations this year that are all men – Tuvalu (three delegates), Niger (three), North Korea (two) and Nicaragua (one) – and one that is all women (Nauru, with five delegates).
The full list of COP30 party delegation sizes can be found here.
(For previous COPs, see Carbon Brief’s delegate analysis for COP21, COP23, COP24, COP25, COP26, COP27, COP28, COP29)
The post Analysis: Which countries have sent the most delegates to COP30? appeared first on Carbon Brief.
Analysis: Which countries have sent the most delegates to COP30?
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