The Intergovernmental Panel on Climate Change’s (IPCC) latest assessment cycle has been beset by disagreements between nations over the timeline for publishing its next landmark report.
During the UN climate science body’s last five “sessions” – biannual meetings where governments discuss matters related to the IPCC’s work – governments have been unable to sign off on the delivery date of the “working group” reports.
The deadlock over the delivery plan for the seventh assessment cycle (AR7) has been described as “unprecedented”.
Some countries have pushed for reports to be approved in 2028, in time to inform the “second global stocktake”, which is due to conclude at COP33 that year and is designed to inform the next round of national climate goals under the Paris Agreement.
Other nations have argued that developing countries need more time to review and approve the reports – meaning that one, or more, would not be published until after the stocktake.
The next IPCC meeting – due to take place in Addis Ababa in October – is likely the last moment where a timeline could be agreed that would see the reports synchronised with the stocktake.
One expert tells Carbon Brief that the failure to align the IPCC’s reports with the stocktake would be a “major historical break [that] would be used to weaken the international climate process and Paris Agreement”.
In this Q&A, Carbon Brief explores the ongoing disagreements over the AR7 timeline.
- How does the IPCC assessment report cycle work?
- How have timeline negotiations been different for AR7?
- Why have negotiations over the timeline of AR7 faltered?
- Why are some countries calling for a slower timeline for AR7 reports?
- How is the IPCC managing the impasse?
- Is delivering the reports in time for the global stocktake still possible?
- What could be the implications of an extended timeline for AR7?
How does the IPCC assessment report cycle work?
For almost 40 years, the IPCC has been one of the most visible examples of a “science-policy interface” – an institution that helps science to inform policy.
The UN General Assembly resolution that established the IPCC in December 1988 states that the panel will “provide internationally coordinated scientific assessments of the magnitude, timing and potential environmental and socioeconomic impact of climate change and realistic response strategies”.
Four years later, the UN Framework Convention on Climate Change (UNFCCC) was created, with an objective of “stabilising greenhouse gas concentrations at a level that would prevent dangerous anthropogenic [human-caused] interference with the climate system”.
The IPCC’s official rulebook, last updated in 2013, highlights the IPCC’s role in producing comprehensive assessments of the state of human-caused climate change. It stipulates that its assessments must provide “relevant” information – and that reports should be “neutral with respect to policy”.
The IPCC’s work has long helped inform the work of the UNFCCC, which meets annually for its “conference of the parties” (COP).
For example, the reports of the fifth assessment cycle (AR5), published over 2013-14, have been credited for informing the Paris Agreement’s headline goal to hold global temperature rise at “well below 2C” and “pursue efforts” to limit increases to 1.5C.
During each assessment cycle, the IPCC produces three “working group” (WG) reports on physical science (WG1), impacts and adaptation (WG2) and mitigation (WG3). These are summarised in a “synthesis” report (SYR). It also produces special reports and methodology reports.
There are a number of stages to the creation of an IPCC working group report, as shown in the graphic below.
How have timeline negotiations been different for AR7?
The current assessment cycle – AR7 – formally began in July 2023, at the IPCC’s 59th session (IPCC-59) in Nairobi.
In January 2024, governments agreed to publish the AR7 synthesis report in 2029.
However, governments are yet to ratify a timeline for publication of the working group reports that will precede it, after negotiations on the issue ended in deadlock in Istanbul, Sofia, Hangzhou, Lima and Bangkok.
This puts AR7 at odds with the previous assessment cycles, where timelines were agreed more quickly. This is shown in the table below.
| Assessment cycle | Start date | Report timeline agreed* | Time until decision | WG1 | WG2 |
WG3 | SYR |
|---|---|---|---|---|---|---|---|
| First | IPCC-1, Nov 1988 | IPCC-2, Jun 1989 | 7 months | Aug 1990 | Jun 1990 | Jun 1990 | Aug 1990 |
| Second | IPCC-7, Feb 1992 | IPCC-9, Jun 1993 | 1 year, 4 months | Dec 1995 | Oct 1995 | Oct 1995 | Dec 1995 |
| Third | IPCC-13, Sep 1997 |
IPCC-14, Oct 1998 | 1 year, 1 months | Jan 2001 | Feb 2001 | Mar 2001 | Sep 2001 |
| Fourth | IPCC-19, Apr 2002 | IPCC-21, Nov 2003 | 1 year, 8 months | Feb 2007 | Apr 2007 | May 2007 | Nov 2007 |
| Fifth | IPCC-28, Apr 2008 |
IPCC-31, Oct 2009 | 1 year, 5 months | Sep 2013 | Mar 2014 | Apr 2014 | Nov 2014 |
| Sixth | IPCC-42, Oct 2015 |
IPCC-46, Sep 2017 | 1 year, 11 months | Aug 2021 | Feb 2022 | Apr 2022 | Mar 2023 |
| Seventh | IPCC-59, Jul 2023 |
– | 2 years, 9 months and counting | – | – | – | 2029 |
“Report timeline agreed” refers to when delivery timeline of working group reports was agreed. WG = working group and SYR = synthesis report. Analysis by Carbon Brief.
Why have negotiations over the timeline of AR7 faltered?
Part of the disagreement over the AR7 timeline centres on the question of whether the IPCC’s seventh assessment cycle should align with the second global stocktake, a process that is due to culminate in the autumn of 2028 at COP33.
While a number of different timelines have been proposed, there are, broadly speaking, two camps in the AR7 timeline debate.
The first group has argued that all three working group reports should be published in 2028, so that they can inform the second global stocktake.
The other faction has advocated for a longer timeline, which would mean WG2 and WG3 would be finished after the stocktake is completed.
Established in 2015 under the Paris Agreement, the global stocktake is a five-yearly assessment of the world’s collective progress on tackling climate change. Under the terms of the treaty, countries pledged to consider the “best available science” during the process.
The first global stocktake concluded at COP29 in Dubai in 2023. Its outcomes informed national 2035 climate goals, which were due to the UN in 2025.
In the outcome decision of the first global stocktake, the UNFCCC officially invited the IPCC to consider how to “best align” with the “second and subsequent global stocktakes”.
The document also invited the IPCC to “provide relevant and timely information for the next global stocktake”.
Dr Bill Hare, CEO and senior scientist of Climate Analytics, tells Carbon Brief the stocktake is “at the guts, or heart, or the Paris Agreement’s ambition mechanism”.
He explains that the IPCC’s sixth assessment reports (AR6) – published over 2021-23 – were a “critical element” in the first global stocktake process:
“You had the IPCC reports there. You’ve had the IPCC co-chairs, or authors, in the discussions [and] workshops, pushing back on arguments from [countries]…They were able to anchor the fact that the world hasn’t done enough, that the NDCs [“nationally determined contributions”, or climate pledges] haven’t met the 1.5C goal by a wide margin – and that the cost of doing stuff is relatively cheap, which was a critical output of the WG3 report last time.”
Dozens of counties have advocated for a global stocktake-aligned timeline for AR7 reports, arguing that it is critical that findings from all working groups inform the exercise.
For example, the small-island state of Vanuatu said at IPCC-63 in Lima that delaying the reports would deprive countries of important scientific information ahead of key international meetings, according to the Earth Negotiations Bulletin (ENB), reporting from inside the meeting.
Meanwhile, the Netherlands said at IPCC-64 in Bangkok that the delivery of reports after the stocktake would “significantly lower the policy relevance of AR7”, according to ENB.
A timeline where the reports are published ahead of the stocktake has been backed by co-chairs of IPCC reports. (See: How is the IPCC managing the impasse?)
Hare says that, in his analysis, a timeline where the AR7 reports align with the stocktake is supported by the “majority of countries, across geographies and levels of development, including least developed countries and small-island developing states”.
However, a number of emerging-economy nations have argued that a timeline where all reports are delivered by 2028 is too tight.
Why are some countries calling for a slower timeline for AR7 reports?
Among the most vocal proponents for the WG2 and WG3 reports being delivered after the stocktake, according to the ENB’s write-ups of negotiations in Bangkok and Lima, are India, Kenya, Russia and Saudi Arabia.
These countries have argued that authors, experts and governments from developing nations with fewer resources need more time to prepare, review and approve working group reports.
Some of the arguments in favour for a slower timeline are captured below in an excerpt from the ENB’s write-up of last October’s IPCC-63 in Lima.
An article published in 2025 in Africa Climate Insights summarised some of the arguments in favour of a slower timeline. It says a stocktake-aligned timeline would have overlapping review periods for different working group reports that would place more pressure on governments and experts.
It also notes that researchers from the global south – who face greater institutional barriers to publishing research in academic journals – would benefit from a later cut-off date for scientific literature for the AR7 reports. It quotes Dr Patricia Nying’uro – Kenya’s IPCC “focal point” – saying:
“The current timeline does not provide adequate time for developing countries to conduct research, publish their findings and have meaningful input.”
On top of citing inclusivity concerns, countries have also argued that aligning reports with the global stocktake is not an IPCC priority.
For instance, ENB reported at IPCC-64 that Saudi Arabia said “compressing” the cycle to meet “external timelines” would be “improper” because the IPCC “serves a broader mandate than just providing inputs to the global stocktake”.
Meanwhile, Russia said inputs to the global stocktake were “not the key to IPCC success”.
These arguments have faced significant pushback.
At IPCC-63 in Lima, IPCC co-chairs pointed out that overlapping reviews of assessment reports were “intentional” and would allow experts to see both drafts at once, according to ENB.
At the meeting, IPCC chair Prof Jim Skea also pointed to the IPCC rulebook, which states that panel and working group sessions should be scheduled to coordinate “to the extent possible, with other related international meetings”.
Some have contested the framing of a stocktake-aligned timeline as “compressed”.
At IPCC-61 in Sofia, the delegation from Saint Kitts and Nevis argued that the proposed schedule for AR7 was “neither compressed nor rushed”, because, while it was shorter than the schedule for AR6, it would contain fewer special reports.
Meanwhile, at IPCC-62 in Hangzhou, representatives from Luxembourg reminded the conference that AR6 was produced under “global pandemic conditions and was, therefore, delayed”, reported ENB. As such, they said the “proper comparison of the timeline would be to AR5, relative to which the proposed timetable was not rushed”.
(AR6’s seven-year run has been attributed in IPCC documents to the Covid-19 pandemic interrupting workflows and an unprecedented number of reports.)
There have been accusations in some quarters that delegations advocating in favour of a slower timeline are deliberately stalling the process.
For example, in a statement released after the meeting, the French government expressed its “deep concern over attempts to arbitrarily slow down and postpone the publication schedule”.
It said that “any delay in taking into account the relevant scientific data to respond to the climate emergency would seriously compromise climate action on a global scale”.
Some observers have argued that dynamics playing out at the IPCC replicate those in UN climate negotiations. Yao Zhe from Greenpeace East Asia tells Carbon Brief:
“The group of countries that opposed the proposed AR7 timelines is similar to the group that tactically slowed down or blocked negotiations regarding mitigation ambition under the UNFCCC. And they are gaining more influence as global climate governance faces a leadership vacuum.”
Dr Kari de Pryck, a lecturer at the Institute for Environmental Sciences at the University of Geneva, tells Carbon Brief that, “clearly, there is obstruction”. She continues:
“It is in the interest of some countries to ensure that the IPCC reports are not published on time. But there are also interesting and legitimate comments on inclusivity and diversity.”
How is the IPCC managing the impasse?
Despite no formal timeline for report delivery being agreed, report production has continued undeterred, IPCC chair Prof Jim Skea tells Carbon Brief.
He says that, so far, the science “has not been held up” by the report timeline issue, with lead author meetings and drafting of the various working group, special and methodological reports underway.
However, he warns that a final decision will need to be made by the end of 2026 on a timeline. He explains:
“There are multiple proposals that have been made [on timelines] and they start to diverge during 2027 due to the scheduling of specific events, like lead author meetings and review periods. Because we need to establish a budget for 2027, we need to make a decision before the end of 2626 to have some certainty about the entire cycle.
“So far, we’ve operated by taking year by year decisions – you just take the decision for the next year and carry on. That’s been okay so far, because there has not been a divergence [between timeline proposals] at the earlier stages of the cycle. But we will see divergences coming up.”
At IPCC-63 last October, WG1 co-chair Dr Robert Vautard noted that reports production was currently aligned with a schedule that had been “considered” in the previous meeting in Hangzhou. He said this timeline would allow final approval sessions for WG1, WG2 and WG3 to take place in May 2028, June 2028 and July 2028, respectively.
After this timeline failed to garner consensus, WG1 co-chair Dr Xiaoye Zhang and WG2 co-chair Dr Bart Van den Hurk then presented a new “compromise” timeline to delegates.
This extended the expert and government review periods for draft reports and pushed final approval sessions for WG2 and WG3 to July 2028 and September 2028. Discussions about this updated timeline ended in deadlock.
At IPCC-64 in Bangkok in March 2026, the timeline for reports was initially not slated for discussion.
However, an item on “progress on AR7 reports” was added to the agenda on the first day of the conference, after some countries said the issue required structured discussion. In the end, no agreement was reached on how resolution could be reached.
Negotiations have been pushed – alongside a number of other unresolved decisions – to IPCC-65, scheduled to take place in Addis Ababa, Ethiopia, in October 2026.
Skea says the lack of agreement on a way forward in Bangkok leaves the secretariat with the “responsibility to try and figure out the process that will move us in the right direction”. He adds:
“Is there a bridging proposal, some kind of scheme that would help to bring the sides together? That’s what we need to work on over the next few months.”
A key issue the secretariat will need to consider is how to address a “loss of trust between different groups of countries”, as well as the “technicalities of how the timeline is constructed”, he says.
Is delivering the reports in time for the global stocktake still possible?
The IPCC maintains that delivering reports in time for the next global stocktake remains possible, if a decision is made by the end of this year.
Speaking to Carbon Brief, Skea says all timeline options in contention are still feasible “in principle”, if countries show flexibility. He counts four different proposals – two of which would see all reports produced before the stocktake in 2028 and two where WG2 and WG3 would be published in 2029.
He says, though, that he is optimistic a “constructive” result can be delivered in Addis Ababa – but stresses it will only be possible with “a lot of hard work”.
Experts have noted that, even if reports are published in 2028, they will come later in the stocktake process.
Dr Matti Goldberg, director of international climate policy at the Woodwell Climate Research Center and former staffer at the UNFCCC secretariat, explains:
“It is already kind of late. If you want to have a meaningful consideration of the IPCC reports in the global stocktake, they need to be there now or at the beginning of the information collection stage. Otherwise, you’ll have a bunch of parties saying: ‘No, can’t do it. It is too short a timeframe, too big a report.’”
The global stocktake is a process that is split into three phases: an information collection phase to gather inputs; a technical assessment of inputs and other evidence; and a “consideration of outputs” phase where countries decide what to collectively take away from the process.
The information phase of the second global stocktake is due to kick off at COP31 in Antalya, Turkey in November 2026. The technical assessment phase will take place from June 2027 to June 2028, giving way to the final political phase that culminates at COP33 in November 2028.
Under the revised AR7 timeline proposed by IPCC co-chairs in Lima, WG1 would be ready during the technical phase of the second global stocktake and WG2 and WG3 would be able to inform its final, political phase.
Goldberg emphasises that the publication of the reports – and their respective summaries for policymakers – in 2028 would mean countries would face “much higher pressure to deliver stronger messages of ambition” in the second global stocktake.
However, he adds that a faster timeline for the reports will not change the “fundamental calculations of interest” that shape international climate politics:
“There are a series of negotiations: first, over the summary of policymakers and then throughout the whole global stocktake. In the end, that is the process that determines a lot of the result.”
De Pryck from the University of Geneva similarly notes that scientific input is not “the only input” to the stocktake:
“It is a political process. So, at the end of the day, science and expertise is very important – but it’s not going to translate directly into the global stocktake.”
What could be the implications of an extended timeline for AR7?
If AR7 reports are not published until after the global stocktake, governments would likely turn to other sources of science in their submissions, experts tell Carbon Brief.
De Pryck explains that a broad range of science was submitted by governments to the first global stocktake. She says this includes the UN Environment Programme’s annual adaptation and emissions gap reports; updates from the International Energy Agency and climate-finance analysis from Oxfam:
“There are quite a lot of other academic and epistemic reports that could be used by countries in the negotiations that, in a way, could support what the IPCC is doing.”
Greenpeace Asia’s Yao Zhe notes that AR7’s special report on climate change and cities, due to be published in 2027, could play a “good scientific basis” for policy discussions around climate mitigation in the absence of the WG3 report from the stocktake.
Climate Analytics’ Bill Hare warns that a failure to align the the IPCC cycle with the global stocktake could result in less robust science being considered:
“There’s a general consensus that the IPCC is the best available science. It is the formal science, if you like, delivered to the Paris Agreement and climate convention. So, if that doesn’t happen, then it opens the space for other sources of so-called science to come in.”
He adds that any disconnect between the global stocktake cycle and the IPCC assessment cycle would be a “major historical break and one which would be used to weaken the international climate process and Paris Agreement”.
The impacts would also be felt within the climate science community, Hare continues. The IPCC’s role in advising the UNFCCC has long provided a “really strong sense of relevance” to many climate scientists, he says:
“That relevance is a very strong motivator for what [scientists] do. I wonder whether the failure of the IPCC to agree timetable alignment would have a negative impact on that. And that wouldn’t be just for this global stocktake cycle, it would be for subsequent ones.”
The post Q&A: Why the standoff between nations over the next IPCC reports matters appeared first on Carbon Brief.
Q&A: Why the standoff between nations over the next IPCC reports matters
Temperatures during the pilgrimage in Saudi Arabia are rising as climate change accelerates, according to a growing body of research.
More than 1.7 million people participated last week in the annual Islamic pilgrimage to Mecca in Saudi Arabia—consistently one of the world’s largest mass gatherings.
Climate Change
Colorado River Faces ‘Devastating Consequences’ If Another Dry Winter Lands, Experts Warn
Even a huge snowpack during the coming winter would only give the river basin states less than two years of storage before reservoirs returned to historic lows.
Another warm, arid winter could leave Colorado River reservoirs nearly dry.
Colorado River Faces ‘Devastating Consequences’ If Another Dry Winter Lands, Experts Warn
Carbon dioxide removal (CDR) technologies will need to be deployed at rates even faster than those seen for solar power, if the world is to have a chance of limiting global warming to 1.5C by 2100, says a new report.
Nearly all pathways to meeting the Paris Agreement’s highest ambition of keeping global temperatures to 1.5C above pre-industrial levels in 2100 involve CDR techniques – ranging from tree-planting to sucking CO2 from air with machines.
This is in addition to steep and immediate emissions cuts.
Scientists expect carbon emissions to push warming beyond 1.5C in the decade ahead, meaning that the target can only be achieved “from above” via large-scale CDR that brings down global temperatures.
These temperature trajectories are known as “overshoot” pathways.
The third “state of CDR” report, written by more than 50 scientists, says that countries’ current CDR plans would fall short of what is needed to limit warming to 1.5C by more than 5bn tonnes of CO2 (GtCO2) per year by 2050.
Global CDR would have to increase fourfold – from 2.2GtCO2 in 2026 to 8.75GtCO2 by 2050 – to have a chance of meeting the 1.5C target by 2100, according to the report.
It adds that deploying CDR can be a “gradual process”, making the period 2026-30 “crucial” for “establishing CDR’s role in limiting climate damages” in the future.
Below, Carbon Brief covers the key findings of the third state of CDR report. (This follows from Carbon Brief’s coverage of the first report in 2023 and second report in 2024.)
- What is CDR?
- What are current levels of CDR?
- How much CDR is needed to reach net-zero goals?
- What does the science say about the potential and costs of CDR?
- What have governments pledged on CDR?
- What is the current funding and research landscape for CDR?
- How is policy impacting CDR demand?
What is CDR?
According to the report, the definition of CDR is:
“Human activities capturing CO2 from the atmosphere and storing it durably in geological, terrestrial or ocean reservoirs, or in products. This includes human enhancement of natural removal processes but excludes natural uptake not directly caused by anthropogenic [human-caused] activities.”
In addition to this, the report includes “three key principles” for CDR, which are:
- The captured CO2 must come from the atmosphere, not from “fossil sources”.
- The subsequent storage “must be durable”, so that the CO2 is not soon reintroduced to the atmosphere.
- The removal must result from human intervention that is in addition to Earth’s natural processes.
In this report, a CDR method is considered durable if it is able to lock up carbon for “decades or more”.
The report classifies CDR techniques as either “conventional” or “novel”.
“Convential” CDR techniques are “well established, already deployed at scale and widely reported by countries as part of [land-use] activities”.
The methods included in this group are tree-planting, ecosystem restoration, agroforestry (trees in agriculture), improving soil carbon in croplands and natural lands, and durable wood production.
“Novel” CDR techniques have “lower level of readiness for deployment and, as a consequence, are currently deployed at smaller scales”, says the report.
Some examples of different CDR methods are listed on the graphic below.
The graphic also shows whether carbon is captured through biological or chemical processes, as well as how “ready” the method is and for how long it can store carbon, among other features.
The report says that CDR is “needed alongside deep and rapid emissions reductions” to give Earth a chance of limiting global warming to 1.5C. It continues:
“It should play a smaller role than emissions reductions given uncertainty around the feasible levels of scaling, sustainability limits, storage availability and the risk of reversal, among other constraints.
“In general, CDR should be seen as a limited resource that will need to be used prudently.”
It adds that CDR can “fulfil three major functions”.
In the near term, CDR can help reduce “net emissions”, it says.
In the medium term, CDR can “counterbalance residual emissions” to achieve net-zero CO2 or net-zero greenhouse gas emissions, the report continues.
(“Residual emissions” are those that cannot be eradicated through technologies or societal changes, such as methane emissions from rice production.)
Research suggests that global warming is likely to stop, more or less, once net-zero is achieved globally.
In the long term, CDR can “help achieve net-negative emissions”, a state where CO2 removal exceeds emissions, says the report.
In this state, humans could lower global temperatures. This may allow the world to limit global warming to 1.5C by 2100, even if the temperature target is surpassed earlier on in the century.
Future trajectories where temperatures exceed the 1.5C limit before being brought back down again through CDR techniques are known as “overshoot” pathways.
What are current levels of CDR?
The report says that, at present, “99.9%” of existing CDR is conventional, land-based techniques such as tree-planting and ecosystem restoration.
The world currently removes 2.2GtCO2 per year, equivalent to around 5% of gross global CO2 emissions, it continues.
The largest contributors to removing CO2 from the atmosphere are China, the US, the EU, Brazil and Russia.
The chart below shows the amount of CO2 removed each year over 2014-23 by the largest contributors, through tree-planting (afforestation) and forest restoration (reforestation).
“Novel” CDR, such as biochar and direct air capture, currently removes just 2m tonnes of CO2 annually at present, according to the report.
However, these methods have been growing at a rate of 40% per year – “similar to successful technologies like solar energy, but insufficient for the scale-up required to meet the Paris temperature goal”, says the report.
The graphic below illustrates how the contribution of conventional CDR currently dwarfs novel CDR, but how the latter techniques are quickly growing.
The report says that investment in CDR companies recovered in 2025 following a dip – and its “share of all climate-tech funding” grew to 2.6%.
The report also notes that, at present, most CDR efforts are unevenly distributed across the world.
For example, two-thirds of conventional CDR in voluntary carbon markets is in Latin America, according to the report. (Voluntary carbon markets are where companies can buy credits for carbon-reducing or removing projects, such as tree-planting, to claim that they have “offset” some of their own emissions.)
In addition, most pilot projects that aim to demonstrate novel CDR methods are located in only a few countries, such as Sweden, Denmark and the US, says the report.
The chart below shows the location and timeline of demonstration projects that have been announced, are under construction or in operation globally.
The report continues:
“While first-movers play important roles, if their actions do not diffuse more widely, vulnerability emerges, as evidenced by the impact of US climate policy dismantling.”
(For more, see: How is policy impacting CDR demand?)
How much CDR is needed to reach net-zero goals?
The report examines three scenarios where global temperature rise is limited to “well below” 2C by 2100:
- A current ambition scenario, based on national climate pledges (but omitting the US);
- A highest-possible ambition scenario;
- A delayed ambition scenario, which is consistent with current targets until 2035 and then switches to the highest ambition scenario.
The pledges considered in the report are “nationally determined contributions”, or NDCs, which countries submit periodically to the UN Framework Convention on Climate Change (UNFCCC). NDCs lay out a country’s climate ambition.
Under the current ambition scenario, the report projects a total of 5.9GtCO2 of CDR by 2050 and 12GtCO2 by 2100.
This scenario would result in end-of-century warming of 1.7-2.7C. Importantly, the report says, this scenario does not result in the world reaching net-zero CO2 levels, “meaning that global temperatures would continue to rise, albeit at a much more gradual pace, beyond 2100”.
Under the highest-possible ambition scenario, CDR scales up to 8.8GtCO2 by mid-century and 15.3GtCO2 by the end of the century.
This scenario assumes “full buy-in by all nations”, with economics, scale-up and sustainability providing the main constraints on CDR deployment, the report says.
The highest ambition scenario results in global temperatures peaking at 1.7-1.8C around 2050 and the world achieving net-zero emissions around that time.
Under the delayed ambition scenario, CDR would scale up to 7GtCO2 by 2050 and 23.6GtCO2 by 2100. This scenario shows global temperatures peaking between 1.7C and 2.0C.
This scenario requires larger CDR deployment in the long term than the highest-ambition scenario does, due to the larger cumulative emissions caused by delaying deep emissions reductions.
In both the high ambition and delayed ambition scenarios, the world reaches “deeply net-negative CO2 emissions” by 2100, the report says. This continued deployment of CDR will further draw CO2 from the atmosphere, lowering global temperatures back down to 1.5C.
The chart below shows annual global greenhouse gas emissions through the end of the century under current ambition (red), highest ambition (green) and delayed ambition (blue) scenarios.
While global CDR capacity scales up more slowly in the first and third scenarios, the report notes that, in all three cases, “novel CDR reaches gigatonne-scale deployment by 2050”.
What does the science say about the potential and costs of CDR?
There is a wide range of both carbon-removal potential and associated costs between different methods of CDR, according to the report.
However, it also notes that these numbers “range widely” in the scientific literature.
The discrepancies in estimates of carbon-removal potential are due to a number of factors, the report says, including a lack of available scientific data, inconsistencies in the assumptions made in assessing technical feasibility and a lack of agreement on what, exactly, “potential” means.
These elements also influence the cost of different CDR methods, but additional factors – such as deployment costs in different areas, technological approaches and scope – also play a role in establishing price differences. Because of this, the report says, “cost estimates are often difficult to compare across methods, complicating design and policy decisions”.
The chart below shows the reported range of mitigation potential (left) and reported range of costs (right) for different CDR methods. The top four rows indicate conventional CDR methods, while bottom 11 rows show novel CDR methods. The chart refers to “mitigation potential”, rather than removal potential, because some estimates do not distinguish between removals and avoided emissions.
(Avoided emissions refers to the difference in emissions from carrying out a project, compared to a hypothetical alternative – such as the reduced emissions from halting deforestation.)
The darker colours indicate estimates that are more constrained, meaning that they are either based on stricter assumptions or there is more agreement between different estimates.
The report notes that for most removal methods, the low end of the potential is around 1GtCO2 per year, while the upper limit of costs is more than $200/tCO2.
The least expensive CDR approaches are forestry-based methods, soil-carbon sequestration and biomass burial. For forestry-based methods, the report puts the cost of CDR at $5-$53 per tonne of CO2 removed. Soil-carbon sequestration costs reach as high as $150 per tonne of CO2 removed, but could have negative overall costs “when accounting for crop yield increases potentially resulting” from changed farm-management practices, the report says.
However, it adds that “these CDR methods are typically associated with lower levels of permanence” than other methods.
Other relatively low-cost methods include coastal wetland restoration, biochar, bioenergy with carbon capture and storage (BECCS) and enhanced rock weathering, while ocean alkalinity enhancement is a medium-cost option.
The most expensive methods include direct air carbon capture and storage (DACCS) and direct ocean carbon capture and storage (DOCCS).
The report also notes that a total estimate of CDR removals cannot be obtained by adding up the removal potential of all of the separate methods, since different methods can compete for scarce resources. For example, BECCS, biochar, biomass burial and biomass sinking all rely on the same base input – biomass – and therefore cannot all be maximised at the same time.
What have governments pledged on CDR?
While many countries include some amount of CDR in their national climate plans, there is currently a large gap between the amount of CDR pledged in these plans and the amount that will be needed to limit global temperature rise to 1.5C by the end of the century, says the report.
This quantity is referred to as the “CDR gap” – the difference between what is pledged and what is needed.
The size of the CDR gap is dependent not just on the pledges made by countries, but also the choice of the “benchmark” scenario against which the pledges are measured. Lower – or delayed – emissions reductions lead to larger shortfalls in the long term, meaning “CDR must subsequently be scaled to very high levels”, says the report.
Current NDCs and other country submissions to the UNFCCC total 2.5GtCO2 per year of removals in 2030, 2.7GtCO2 per year in 2035 and 3.6GtCO2 per year in 2050.
This gives a CDR gap of 0.3GtCO2 in 2030, 1.2GtCO2 in 2035 and 5.2GtCO2 in 2050, according to the report. These figures are obtained using assumed “immediate, ambitious action at all levels to reduce emissions” and the most-ambitious estimates of CDR set out in national pledges. Together, this provides a “lower bound” for the CDR gap, says the report.
By comparison, a 10-year delay in implementing ambitious emissions reductions will result in the need to remove at least an additional 150GtCO2 from the atmosphere, compared to the most ambitious scenario. (See: How much CDR is needed to reach net-zero goals?)
The report says that the CDR gap has widened since the second state of CDR report was released in 2024, due to the US leaving the Paris Agreement. It adds that other countries have “not delivered a step change in ambition” in their latest round of climate pledges.
It also cautions that “credibility issues with national pledges may mean that the CDR gap is actually larger than what we assess here”.
The report notes that current CDR pledges by companies are “substantially higher than country pledges”, at 5GtCO2 per year in 2050. However, it adds, “credibility in these announcements is low”.
What is the current funding and research landscape for CDR?
Funding of CDR research and development – as well as investment in CDR companies – has continued to increase in recent years.
In total, there has been around $5.6bn in grant funding distributed to CDR research since 2005, according to the report’s analysis. Roughly one-third of this has come in the past three years.
Funding for CDR research grants grew 13% each year between 2022 and 2025, the report says, and the corresponding number of research publications grew at a similar rate.
Funding was largely targeted at a handful of key areas, notably soil carbon sequestration, biochar and forest-based CDR.
DACCS and BECCS only make up a small number of active grants, but together account for around two-fifths of all funding due to “substantially larger” project sizes.
Despite the growth of research grants and scientific publications, the report concludes that early-stage innovation in CDR is “uneven” and says there is “no strong evidence of a step-change”.
It notes that much of the support for CDR has come from projects with a broader focus, rather than those that focus specifically on CDR.
The authors also point to a decline in “inventive activity”, as measured by patenting of CDR-related innovations. While patenting for emissions-cutting technologies in general has been on an upward trajectory, CDR patenting peaked in 2011.
Meanwhile, the report highlights the “remarkable” sustained investment in CDR companies, against a backdrop of falling investment in climate-related technologies. It notes that CDR now accounts for around 3% of overall “climate-tech funding”.
Yet, again, it says future developments remain “uncertain”. Since the previous 2024 “state of CDR” report, companies have scaled back their ambitions and policy reversals – notably in the US – “underscore that funding uncertainty remains a key barrier”. (See: How is policy impacting CDR demand?)
An upward tick in funding in 2025 was driven primarily by a “surge” in grants from predominantly public institutions, as well as $0.5bn in debt financing for a single BECCS project in Sweden.
Reliance on such funding sources “highlight[s] the volatility of the CDR innovation ecosystem”, according to the report.
The report also has a chapter focusing on the voluntary carbon market, which it describes as “propelling most of the current demand for novel CDR”.
The scale of this market remains fairly small, with contracts for 0.04GtCO2 of removals signed last year.
Moreover, the concentration of sales within a small number of buyers – particularly Microsoft – remains a “critical vulnerability”, the authors note.
How is policy impacting CDR demand?
The report analyses CDR policies in G20 nations – which together account for three-quarters of global emissions – to assess how they are acting to support CDR across their economies.
In total, 140 countries have announced net-zero targets, including virtually all of the world’s major emitters. In doing so, the report points out that the governments of these nations have “implicitly included a role for CDR in their climate plans”.
However, this does not always translate into measures specifically designed to scale up CDR.
Only the EU has adopted a binding, quantified removals target into law – namely, the goal to reach 310m tonnes of CO2 equivalent (MtCO2e) of annual net removals in the land sector by 2030.
Overall, conventional CDR is the main focus of policy, with various governments focusing on tree planting to absorb CO2 from the atmosphere.
Among G20 nations, only the UK and Australia have set specific goals to scale up novel CDR, such as BECCS and DACCS, over the coming decade.
The report highlights some nations, including Canada, Germany, Switzerland and the UK, as taking proactive steps to incentivise CDR.
The authors point to national strategies, financial support for CDR and efforts to integrate it into emissions trading systems (ETS) as examples of effective policy making.
(The report also stresses that the US, which was previously a “leader” on CDR, has now “frozen or dismantled funding and support” for CDR under the Trump administration.)
Most of the successful policies highlighted in the report focus on supporting the supply of CDR, with “less attention so far on creating demand”.
This is significant because CDR “generally lacks a natural market”, meaning there are not automatically buyers willing to spend money on emissions removals. Therefore, the authors say, policy interventions are important to create markets and boost demand.
“Compliance” carbon credits – referring to credits that can be used to meet legally mandated emissions targets – provide a way to support demand, according to the report authors.
Only some ETSs, such as those used in New Zealand and Australia, allow the use of credits based on forest-related removals for compliance. (It is worth noting that such credits are controversial, as removals by forests are not always permanent.)
The report also highlights the need for “foundational policies to create a governance framework for CDR, including rules for quantification of removal, guidelines for community engagement and the minimisation of negative environmental impacts”.
The post Q&A: The current state of ‘carbon dioxide removal’ around the world appeared first on Carbon Brief.
Q&A: The current state of ‘carbon dioxide removal’ around the world
-
Climate Change10 months ago
Guest post: Why China is still building new coal – and when it might stop
-
Greenhouse Gases10 months ago
Guest post: Why China is still building new coal – and when it might stop
-
Greenhouse Gases2 years ago嘉宾来稿：满足中国增长的用电需求 光伏加储能“比新建煤电更实惠”
-
Climate Change2 years ago嘉宾来稿：满足中国增长的用电需求 光伏加储能“比新建煤电更实惠”
-
Climate Change2 years ago
Bill Discounting Climate Change in Florida’s Energy Policy Awaits DeSantis’ Approval
-
Renewable Energy7 months agoSending Progressive Philanthropist George Soros to Prison?
-
Carbon Footprint2 years agoUS SEC’s Climate Disclosure Rules Spur Renewed Interest in Carbon Credits
-
Greenhouse Gases11 months ago
嘉宾来稿：探究火山喷发如何影响气候预测