Question:
You are given the full text of a scientific research paper.

    Summarize the **research methods** used in the study in a way that is informative for policy audiences. Your response should:
    - Describe the overall study design, data sources, tools, and models used
    - Avoid unnecessary technical details or equations
    - Use accessible but precise language

    Write a short paragraph suitable for the “Scientific Research Study Methods” section of a policy brief.

    Scientific Research Paper:
    Nature Climate Change | Volume 14 | June 2024 | 644–651
644
nature climate change
Analysis
https://doi.org/10.1038/s41558-024-01984-6
The carbon dioxide removal gap
William F. Lamb
  1,2
, Thomas Gasser3, Rosa M. Roman-Cuesta4,
Giacomo Grassi
  4, Matthew J. Gidden
  3, Carter M. Powis5, Oliver Geden
  6,
Gregory Nemet
  7, Yoga Pratama
  3, Keywan Riahi
  3, Stephen M. Smith
  5,
Jan Steinhauser
  3, Naomi E. Vaughan
  8,9, Harry B. Smith
  8,9 &
Jan C. Minx
  1,2
Rapid emissions reductions, including reductions in deforestation-based
land emissions, are the dominant source of global climate mitigation
potential in the coming decades. However, carbon dioxide removal (CDR)
will also have an important role to play. Despite this, it remains unclear
whether current national proposals for CDR align with temperature targets.
Here we show the ‘CDR gap’, that is, CDR efforts proposed by countries fall
short of those in integrated assessment model scenarios that limit warming
to 1.5 °C. However, the most ambitious proposals for CDR are close to levels
in a low-energy demand scenario with the most-limited CDR scaling and
aggressive near-term emissions reductions. Further, we observe that many
countries propose to expand land-based removals, but none yet commit to
substantively scaling novel methods such as bioenergy carbon capture and
storage, biochar or direct air carbon capture and storage.
CDR can support climate mitigation in three ways1,2. First, in the
short-term, it can reduce net emissions. While many CDR methods
are costly and technologically immature, afforestation and land-based
removals already make a contribution today. Second, in the mid-term,
CDR can counterbalance residual emissions in ‘hard-to-abate’ sectors,
allowing countries to reach their stated net-zero CO2 or greenhouse gas
(GHG) emissions objectives. And third, in the long-term, CDR could
be used to reach net-negative emissions. This could compensate for
historical emissions and allow global temperature exceedance to be
reversed (however, it would not avoid the impacts associated with an
overshoot of 1.5 °C, such as biodiversity loss and sea level rise)3.
Yet despite the apparent importance of CDR, there are few dedi-
cated efforts to track real-world deployments, commitments, policies
or related developments in the sector2,4. By contrast, tracking is widely
available for emissions reductions5–7. In particular, none have evaluated
the removal component of the ‘emissions gap’—a science-policy device
for assessing progress towards the Paris Agreement temperature goal,
published each year in the Emissions Gap Report7 and supported by an
underlying evidence base8–10. So far, the emissions gap has been formu-
lated in terms of net GHG emissions, with no distinction having been
made between gross emissions and removals (Fig. 1). This simplifies the
assessment to a single aggregated gap and recognizes certain empirical
realities: most countries do not distinguish emissions and removals
in their targets, and integrated assessment model (IAM) reporting
has tended to combine emissions and removals on managed land as
a single net indicator. However, there are several compelling reasons
why CDR should be distinguished in the gap analysis.
In the first instance, this is a simple transparency issue. As many
countries have pledged net-zero targets, an assessment of their implied
emissions and removals will provide a better understanding of how
countries want to achieve these goals11. In turn, this opens a space for
critical reflection on the fairness and ambition of proposed reductions,
levels of residual emissions and potential overdependence on CDR12–16.
A second reason is that emissions and removals are fundamentally dif-
ferent categories, involving different technologies, implementation
options and risks, with varying policy and governance requirements
Received: 11 July 2023
Accepted: 19 March 2024
Published online: 3 May 2024
 Check for updates
1Mercator Research Institute on Global Commons and Climate Change (MCC), Berlin, Germany. 2Priestley International Centre for Climate, University of
Leeds, Leeds, UK. 3International Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria. 4Joint Research Centre, European Commission, Ispra,
Italy. 5School of Enterprise and the Environment, University of Oxford, Oxford, UK. 6German Institute for International and Security Affairs (SWP), Berlin,
Germany. 7University of Wisconsin-Madison, Madison, WI, US. 8School of Environmental Sciences, University of East Anglia, Norwich, UK. 9Tyndall Centre
for Climate Change Research, University of East Anglia, Norwich, UK.
 e-mail: lamb@mcc-berlin.net

Nature Climate Change | Volume 14 | June 2024 | 644–651
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Analysis
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To estimate the CDR gap, we first organize our analysis around
two categories of CDR that differ in terms of scale, technology readi-
ness and permanence: ‘conventional CDR on land’ and ‘novel CDR’.
The former consists of methods conventionally defined as removals
in the land use, land-use change and forestry (LULUCF) sector (for
example, afforestation, restoration). Novel CDR comprises all other
CDR methods, such as biochar, direct air carbon capture and storage
(DACCS) or bioenergy carbon capture and storage (BECCS). (In
Methods, we further explain our definitions, including the notable
exclusion of removals driven by indirect anthropogenic effects).
Whereas conventional CDR on land methods are already widely
adopted and integrated into national climate pledges, novel CDR
methods remain at an early stage of adoption and policy integration2.
Studies are now beginning to report total current CDR deployments
following these definitions18,19, which we estimate as approximately
3 GtCO2 yr−1, of which 99.9% is from conventional CDR on land (Fig. 2)19.
To estimate proposed levels of CDR upscaling by countries, we
draw from documents submitted to the United Nations Framework
Convention on Climate Change (UNFCCC): the nationally determined
contributions (NDCs) and the long-term strategies (also known as
including critical issues such as permanence and land use17. Finally,
while CDR makes a trivial contribution to climate change mitigation
today (Fig. 2), according to scenarios, it could become the dominant
response in the second half of the twenty-first century2. In some coun-
tries with large existing land-based removals, it could become the
dominant response much sooner.
In this Article, we provide a conceptualization and quantification
of the ‘CDR gap’—the gap between levels of CDR that are proposed by
governments and levels of CDR in IAM scenarios that limit warming
to 1.5 °C. Importantly, our evaluation introduces further normativity
into the assessment of global mitigation pledges by making a judge-
ment regarding the appropriate division of effort between emissions
reductions and removals. Concretely, this judgment manifests in the
scenarios we choose as a point of comparison to national proposals,
including the specific amounts and types of CDR they implement,
as well as their rates of emissions reductions. However, rather than
obscure this choice by comparing against broad scenario ranges, we
instead select individual scenarios and aim to discuss and justify our
particular choices, further opening the discourse on ‘how much CDR
is needed’ to meet the Paris Agreement.
Net GHG emissions
Gross GHG emissions
Gross CO2 removals
Range of net GHG emissions in the NDCs
a An assessment of the emissions gap combining emissions and removals
b An assessment of the emissions gap separating emissions and removals
Emissions: Non-CO2 GHGs
Emissions: Fossil CO2
Emissions: Managed land
Removals: Conventional CDR on land
Removals: Novel CDR
2050
The emissions gap
Range of gross CO2

removals in the NDCs
The CDR gap
2010
0
2010
2030
2100
2030
2050
2100
The emissions gap
Range of gross GHG emissions in the NDCs
GHG emissions
0
GHG emissions
Scenario pathway to 1.5 °C or 2 °C
Fig. 1 | Combined versus separate assessments of the emissions and CDR gap. a,b, A stylized scenario pathway that reaches net-zero CO2 and GHG emissions under
combined (a) versus separate (b) assessment. Typically, the gap would be assessed against a scenario range and median level, rather than a single scenario.

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Analysis
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the long-term low-emissions development strategies). These give
insight into levels of CDR in 2030 and 2050, compared to historical
inventory-based reporting. There are currently no strict requirements
for reporting CDR in either of these documents, so several assumptions
must be made to extract this information where it is implicit in national
targets (see Methods).
To benchmark levels of CDR proposed by countries, we use the
compilation of IAM scenarios vetted by the IPCC 6th Assessment
(AR6)1,20. While novel CDR (such as BECCS) is reported in the AR6
scenario database, conventional CDR on land is only inconsistently
reported as afforestation and instead tends to be combined with emis-
sions as a net LULUCF flux. We therefore use a novel re-analysis of
the IPCC database using the OSCAR model that extracts the removal
component of the LULUCF flux in each scenario corresponding to our
definition of conventional CDR on land (see Methods)21.
CDR in national mitigation pledges
Our NDC assessment finds that countries’ conventional CDR on land
will change from −3.0 GtCO2 yr−1 for the period 2011–2020 (that is, the
removals reported in GHG inventories once the indirect effects are fac-
tored out in this study; see Methods) to approximately −3.1 GtCO2 yr−1
(unconditional pledges) or about −3.5 GtCO2 yr−1 (conditional pledges)
in 2030. While some countries include novel CDR in their qualitative
description of mitigation efforts towards the 2030 pledges and a few
provide initial quantifications (for example, Korea, Canada, Norway),
these are currently not possible to distinguish from avoided emissions
(for example, fossil-based CCS). We therefore estimate zero commit-
ments towards novel CDR by 2030, with no change from current levels
of approximately 2 MtCO2 yr−1.
In the case of the long-term strategies, there is a general acknowl-
edgement that CDR is needed to realize national net-zero targets22.
Indeed, most countries include at least a qualitative description of
how this type of mitigation effort would be achieved. However, only
40 countries have outlined scenarios in their long-term strategies
that depict quantifiable levels of CDR by 2050 (28 if EU countries are
combined as one). If we assume that all other countries sustain their
current levels of removals, proposed CDR as reflected in the long-term
strategies range between −4.6 and −5.0 GtCO2 yr−1 in 2050, the major-
ity of which is conventional CDR on land (85% and 81%, respectively).
CDR in mitigation scenarios
In scenarios that limit warming to below 2 °C (see Methods for scenario
definitions), gross emissions reductions are the dominant mitigation
response in the coming three decades. Between 2020 and 2050, emis-
sions are reduced by 62% (46–75%). Subsequently, CDR becomes the
main mitigation strategy in the second half of the twenty-first century,
with scenarios cumulating 670 (450–1100) GtCO2 of removals by 2100.
Novel CDR tends to continuously scale up in scenarios throughout the
twenty-first century and accounts for over half of cumulative remov-
als by 2100. By contrast, conventional CDR on land starts from a high
baseline but quickly reaches saturation by the mid-century due to land
area constraints for afforestation/restoration.
Scenarios vary considerably in their levels and types of CDR
deployment, depending on how policy choices, technology avail-
ability and socio-economic developments shape the speed and depth
of gross emissions reductions (Table 1). We therefore highlight three
‘focus scenarios’ that depict different emission reduction and CDR
pathways to hold warming below 1.5 °C:
BECCS
DACCS
Other
60
0
0
–00005
–0.0010
–0.0015
–0.0020
–0.0025
–1
–2
–3
Gt CO2e
Global total greenhouse gas emissions and removals
Emissions: Non-CO2 GHGS
Emissions: Fossil CO2
Emissions: Managed land
Removals: Conventional CDR on land
Removals: Novel CDR
40
20
0
Fig. 2 | Current global CDR versus emissions. Updated from ref. 19 (see Methods) with additional emissions data from ref. 58, using global warming potentials with
a 100 year time horizon from the IPCC 6th Assessment Report59. Emissions data for 2019 are plotted, while LULUCF removals are the 2011–2020 annual average, and
novel CDR removals are an estimate for 2020.
Table 1 | Reasons why CDR deployments vary in scenarios
Reasons why scenarios deploy more
CDR
Reasons why scenarios deploy less
CDR
• Emissions reductions are
delayed.46,47
• A wider portfolio of CDR methods
are available, lowering their
costs relative to deep emissions
reductions.29,48,49
• The portfolio of mitigation
technologies that can lower
residual emissions at the point of
net-zero CO2 is more limited (such
as CCS for industrial processes).50
• A more-stringent temperature
target is applied, lowering the
available carbon budget.50
• The scenario is permitted to
initially exceed a warming level
and compensate for this with net
negative emissions later in the
century.29
• A temperature target is chosen that
has already been exceeded, such
as 1 °C.51
• For scenarios that use a full-century
carbon budget rather than a peak
budget52, values assumed for
economic discount rates can push
mitigation further into the future.53
• Emissions reductions are faster and
implemented without delay.46,47
• A wider portfolio of (demand-side)
mitigation options are available, with
lower costs relative to CDR.23,54
• A wider portfolio of mitigation
technologies that can lower residual
emissions at the point of net-zero
CO2 is available (such as CCS for
industrial processes).50
• A less-stringent temperature target
is applied, increasing the available
carbon budget.50
• Assumptions differ strongly
about different limitations to
CDR deployment, including both
technological progress55 as well
as social and environmental
sustainability.24,25,56,57. Scenarios may
limit the speed or total quantity of
deployment on the basis of some or
all of these considerations.

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Analysis
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• Focus on demand reduction – a scenario that reduces global
energy demand through efficiency and sufficiency measures, with
a low long-term dependency on CDR23. Annual removals in 2050
are −4.8 GtCO2, entirely from conventional CDR on land.
• Focus on renewables – a scenario that rapidly implements a
supply-side transformation towards renewable energy24. Annual
removals in 2050 are −7.6 GtCO2, including a small contribution
from novel CDR (−0.91 GtCO2).
• Focus on carbon removal – a scenario with rapid near-term emis-
sions reductions but a subsequent incomplete phase out of fossil
fuels, leading to higher residual emissions at net-zero CO2. Annual
removals in 2050 are −9.8 GtCO2, with a large contribution from
novel CDR (−3.5 GtCO2).
The first two of these focus scenarios feature CDR levels at the
lower end of the range in below 2 °C scenarios (see Methods), while the
latter sits just above the median (see Table 2). Scenarios at the upper
end of the below 2 °C range (95th percentile) feature CDR deployments
of −14 GtCO2 yr−1 in 2050—levels that probably encounter feasibility
constraints in terms of scale-up and bioenergy resource availability25.
As all three scenarios hold warming below 1.5 °C with no or limited
overshoot, they mainly differ in CDR upscaling due to the speed of their
near-term reductions and the quantity and type of residual emission
that they need to compensate to reach net-zero CO2 (Fig. 3 and Sup-
plementary Table 1). We include 2 °C (for example, C3) pathways in
the overall scenario range (Fig. 4 and Table 2) but do not select them as
focus scenarios, which would highlight both lower CDR requirements
and lower gross emissions reductions, but also higher climate impacts.
The CDR gap
Across both categories of removals, a CDR gap already emerges by
2030 (Table 2). Compared with 2011–2020, the conditional NDCs would
expand CDR by −0.5 GtCO2 yr−1 in 2030. This contrasts with an increase
of −1 GtCO2 yr−1 in 2030 in the Focus on demand reduction scenario,
which has the lowest CDR requirements. The CDR gap in 2050 is then
strongly determined by the chosen scenario benchmark. Compared
with 2020, additional CDR in 2050 implied by the upper estimate
of the long-term mitigation strategies (from 28 countries including
the EU, assuming all others sustain current removals) would sum to
−1.9 GtCO2 yr−1. This approaches levels in the Focus on demand reduc-
tion scenario (an additional −2.3 GtCO2 yr−1), but falls short by multiple
gigatons compared with the other focus scenarios. The most ambitious
of current CDR plans are therefore close to a conservative level of CDR
scaling, albeit one that would need to be coupled with deep, near-term
emissions reductions.
The gap in conventional CDR on land
Neither the NDCs in 2030 nor the long-term strategies in 2050 propose
levels of conventional CDR on land sufficient to meet those projected
in scenarios (Table 2 and Fig. 4). However, our analysis only captures
countries with quantifiable scenarios, which represent about 38% of
current conventional CDR on land removals. These countries plan
to increase removals by −0.8 to −1.0 GtCO2 yr−1, when adjusting the
long-term strategies to remove ‘indirect anthropogenic effects’ (see
Methods). By contrast, the focus scenarios increase conventional CDR
on land by an additional −2.3 GtCO2 yr−1 (Focus on demand reduction)
to −4.1 GtCO2 yr−1 (Focus on renewables).
Our analysis assumes that all other countries without quantifiable
scenarios (accounting for 62% of current conventional CDR on land)
can sustain their existing removals. This includes China, India and the
Democratic Republic of the Congo, which all have substantial forest
conservation and restoration potentials26 and could be instrumental
in closing the gap in conventional CDR on land.
The gap in novel CDR
No country transparently includes novel CDR as a distinct portion
of their pledged mitigation efforts by 2030. By contrast, below 2 °C
scenarios already implement −0.06 GtCO2 yr−1 of additional novel CDR
by 2030.
Looking forward to 2050, many countries mention novel CDR
in their long-term strategies and some quantify it in their illustra-
tive national scenarios. At the upper estimate, approximately
−0.96 GtCO2 yr−1 of additional novel CDR can be inferred from
these scenarios, largely driven by the US (−0.5 GtCO2 yr−1), Canada
(−0.23 GtCO2 yr−1) and the EU (−0.08 GtCO2 yr−1). This compares to
the −0.91 GtCO2 yr−1 of (global) additional novel CDR in the Focus on
renewables scenario and the −3.5 GtCO2 yr−1 in the Focus on carbon
removals scenario. There is no gap in novel CDR compared with the
Focus on demand reduction scenario, which avoids scaling up novel
CDR entirely (but does, however, scale up conventional CDR on land).
Our analysis assumes that countries without quantifiable sce-
narios do not currently plan to implement novel CDR. This includes
China, Norway and Saudi Arabia, which are all developing technology
roadmaps towards novel CDR and could contribute to closing the gap.
Discussion
Our initial quantification of the CDR gap highlights that countries
also lack progress in this domain of climate mitigation. While some
are planning to scale CDR to meet the temperature goal of the Paris
Agreement, together they fall short by hundreds of megatons in 2030
and by hundreds of megatons to multiple gigatons in 2050, depending
Table 2 | Scaling of CDR to 2030 and 2050 in scenarios, NDCs and long-term strategies (GtCO2 yr−1)
Additional total CDR from 2020
(GtCO2 yr−1)
Additional conventional CDR on
land from 2020 (GtCO2 yr−1)
Additional novel CDR from
2020 (GtCO2 yr−1)
Gross GHG emissions
reductions from 2020 (%)
2030
2050
2030
2050
2030
2050
2030
2050
Below 2 °C scenarios
−1.1
(0.01 to −3.4)
−4.5
(0.92 to −11)
−0.85
(0.014 to −3)
−2.3
(2.5 to −6)
−0.06
(0 to −1.1)
−2.4
(−0.5 to −9.1)
25
(4.2–50)
62
(46–75)
Focus on demand reduction
−1
−2.3
−1
−2.3
0
0
51
78
Focus on renewables
−2.9
−5.1
−2.7
−4.1
−0.14
-0.91
39
80
Focus on carbon removal
−1.6
−7.4
−0.66
−4.0
−0.95
−3.5
40
77
NDCs*
(−0.05 to −0.53)
NA
(−0.05 to −0.53)
NA
0
NA
NA
NA
Long-term mitigation strategies
NA
(−1.5 to −1.9)**
NA
(−0.8 to −1.0)**
NA
(0.7–0.96)*
NA
NA
Below 2 °C scenarios refer to categories C1 and C3 in the AR6 scenario database. For these categories, the median and 5–95th percentiles are reported. In the lower range of some scenarios,
conventional CDR on land decreases compared with 2020, which gives rise to negative numbers. The analysis of the NDCs (*) was complemented by other official reports containing
information on the country’s mitigation targets (for example, National Communications, Biannual Updated Reports, REDD+ documents, national mitigation strategies). The additional CDR in
the long-term mitigation strategies (**) assumes that countries without a quantifiable strategy preserve their current levels of conventional CDR on land. One hundred eleven NDCs (that is,
excluding small island states, city states and countries with no land use fluxes) and all long-term strategies up to November 2023 (COP28) were considered for the analysis.

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on the benchmarked scenario. The importance of planning for CDR
at scale in 2050 is therefore not currently reflected at the policy level,
even under assumptions of rapid and sustained emissions reductions
in the short term. However, three important caveats should be noted
in this Analysis.
First, although most countries have committed to net-zero targets,
they still provide little information on what role CDR will play in reach-
ing them. Within the NDCs, ambiguities and a lack of transparency lead
to wide ranging assessments of not only the land-use flux and implied
removals, but also overall emissions levels27,28. These problems are even
more apparent with the long-term strategies, which lack any common
reporting structure and where underlying scenarios are illustrative
rather than formal commitments13. As of COP28, only 68 countries
(42 when excluding EU countries) have actually submitted a long-term
strategy. Further, not all pledges have an associated climate law in their
home jurisdictions10.
Nevertheless, the NDCs and long-term strategies are among the
few reference points available for evaluating national CDR proposals,
and they are the only documents that can be feasibly analysed and
aggregated for a global assessment. It is therefore critical that future
iterations of these documents contain the required transparency
for evaluating national targets based on both gross emissions
and removals.
Second, IAMs have a prominent role in shaping climate miti-
gation policy advice and have been subject to several criticisms.
Discussions have focused on whether sustainable levels of bioenergy
use are exceeded in scenarios, whether CDR tends to substitute for
short-term emissions reductions, and whether the full scope of low
demand, low CDR, or ‘degrowth’ scenarios has yet been explored29–32.
In addition, IAMs have mainly modelled afforestation, BECCS and
DACCS, while other methods have been scarcely explored29. By drawing
from scenario evidence, this CDR gap assessment is similarly exposed
to such criticisms.
In this assessment, we take a pragmatic approach and recognize
that IAM scenarios provide the best current evidence available to bench-
mark country proposals for CDR. We also select specific focus scenarios
a
b
Emissions: Non-CO2 GHGs
60
Focus on demand reduction
Focus on renewables
Focus on carbon removal
50
40
30
20
Annual GHG emissions and
removals (GtCO2yr−1)
Annual GHG emissions and
removals (GtCO2yr−1)
10
0
–10
60
50
40
30
20
10
0
–10
–20
2020
2060
2100
2020
2060
2100
2020
2060
2100
Emissions: Fossil CO2 (other)
Emissions: Fossil CO2
Emissions: Fossil CO2 (transportation)
Emissions: Fossil CO2 (buildings)
Emissions: Fossil CO2 (industry)
Emissions: Fossil CO2 (energy supply)
Emissions: Managed land
Removals: Conventional CDR on land
Removals: Novel CDR
Net GHG emissions
2020
At time of net-zero CO2
Focus on
demand
reduction
(2052)
Focus on
renewables
(2067)
Focus on
carbon
removal
(2047)
Focus on
demand
reduction
(2098)
Focus on
renewables
(2089)
Focus on
carbon
removal
(2077)
At time of net-zero GHG
Net CO2 emissions
Fig. 3 | The three focus scenarios. a, The emissions and removals pathways of each scenario in the twenty-first century. b, The residual gross GHG emissions and
removals of each scenario at the point of net-zero CO2 and net-zero GHG emissions. The error bar in b depicts the median and interquartile range (n = 189) of gross
emissions and removals in scenarios, sourced from refs. 20,21.

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to increase the transparency in a set of possible CDR futures and their
underlying determinants, but orient our selection to scenarios at the
lower end of CDR requirements. Other selections are possible and can
be made using the supplementary data file of this Analysis. Alternative
approaches for benchmarking CDR levels should also be explored, for
instance by assessing the residual emissions associated with bottom-up
energy and material requirements for meeting human needs33. One area
of needed improvement is the separation of gross LULUCF emissions
and removals in scenario reporting—information that we have sourced
here from a re-analysis of the AR6 scenario database21.
Finally, a recurring concern in the literature is that including CDR
in mitigation discussions may deter near-term emissions reductions34.
States, corporations or other interest groups seeking an excuse for
doing very little may exploit the fact that CDR can compensate for
emissions, overplaying the quantity of removals that may be achieved
at some (later) point in time. Indeed, a variety of claims and discursive
strategies beyond CDR are used to excuse or delay climate action,
which may help political actors resolve the tension between powerful
incumbent fossil interests and increasing domestic or international
calls for climate action35–37. Given the commercial stakes at play, sci-
entists therefore face enormous challenges in facilitating a nuanced
dialogue on CDR.
The assessment we provide of the CDR gap contributes to this
dialogue by asking ‘how much is needed?’ and ‘what are countries
planning?’. We believe it is important to situate such questions in the
scientific literature and provide a space to critically reflect on them.
However, we acknowledge that this will not prevent interest groups
from exploiting the integration of CDR in the climate debate. We there-
fore plainly state: our assessment of CDR in no way underplays the
need for rapid, immediate and deep emissions reductions across all
sectors, including a rapid decrease in fossil fuel use and the halting of
deforestation. Indeed, our Analysis reinforces this fact, as the longer
such reductions are delayed, the higher future CDR requirements are
and the wider the CDR gap becomes.
Conventional and novel CDR (GtCO2 yr−1)
The extent of future carbon dioxide removal depends on the scenario by which climate goals are met
Current and proposed levels of carbon dioxide removal are insuficient to meet the Paris temperature goal
0
a
b
–4
–8
–12
0
–2.5
–5.0
–7.5
–10.0
0
–2.5
–5.0
–7.5
–10.0
2010
Current CDR
NDCs (unconditional)
Long-term strategies (low)
Long-term strategies (high)
NDCs (conditional)
Focus on renewables
Focus on renewables
Focus on carbon removals
Focus on carbon removals
Focus on demand reduction
Focus on demand reduction
2020
2030
2040
2050
Conventional CDR
on land (GtCO2 yr−1)
Novel CDR
(GtCO2 yr−1)
Below 2 °C scenarios
Below 2 °C scenarios
2011–
2020
2030
2050
Current CDR
CDR in Paris-relevant
scenarios
Focus on
renewables
(39% GHG reduction by 2030)
Focus on carbon
removals
(40% GHG reduction by 2030)
Focus on demand
reduction
(51% GHG reduction by 2030)
Fig. 4 | The carbon dioxide removal gap. a, Current levels of CDR and levels
in Paris-relevant scenarios up to 2050. The orange shaded areas depict the
5th–95th (light orange) and 25th–75th (dark orange) percentiles of IPCC C1 and
C3 scenarios that limit warming to below 2 °C. The orange lines depict three
focus pathways that limit warming to 1.5 °C, alongside the gross greenhouse gas
emissions reductions required by 2030 for each. b, Levels of current, proposed
and scenario-based CDR, split by conventional CDR on land and novel CDR in
2020, 2030 and 2050. Pink bars depict proposed CDR levels in the NDCs and
the long-term mitigation strategies. Orange bars depict CDR levels in the three
focus scenarios, as well as the overall scenario medians (centre line) and ranges
(5th–95th (light orange) and 25th–75th (dark orange) percentiles).

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Analysis
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There are varying challenges to closing the CDR gap. While conven-
tional CDR on land is already well integrated into climate governance,
experience has highlighted difficulties in monitoring, reporting and
verification38–40. An overdependence on land-based removals brings
risks for land availability, food production and ownership rights12. On
the other hand, if designed well, they can be integrated with sustainable
development and biodiversity objectives41. In addition, forest carbon
is vulnerable to reversal, and expectations that regional sinks can be
preserved in the coming decades have been challenged, highlighting
the importance of policies that promote sustainable management, pre-
vent illegal removals and limit the impact of natural disturbances42–44.
Regarding novel CDR, there is little existing capacity and rates of
potential scaleup are very high, both in the long-term strategies (up to
0.96 GtCO2 yr−1, or 470 times current levels) and in below 2 °C scenarios
(up to 2.4 GtCO2 yr−1, or 1,200 times current levels, but with some sce-
narios at or near 0). Although technology adoption and scaleup rates
have been impressive in several analogous historical cases45, novel
CDR methods such as BECCS may face headwinds due to high capital
costs, a dependency on state support and other factors. In our view,
near-term policies to support these methods in their formative phase
are urgently needed, without which it is difficult to conceive of any
gigaton-scale contribution from novel CDR in 2050 and beyond. In
addition, regulatory action that robustly defines, monitors, reports
and verifies novel CDR is lagging. Importantly, enhanced emissions
reductions are needed to reduce our dependence on dramatically
scaling up these nascent CDR technologies.
To what extent is the CDR gap due to inadequate proposals by
countries, versus a failure to specify them in the first place? Our analy-
sis of the long-term strategies covers 28 countries (including the EU),
summing to 38% of current removals. Due to this limitation, we assume
that all other countries can sustain their current conventional CDR on
land. This is a generous assumption, given how difficult it will be to sus-
tain such removals amid mounting climate impacts42–44. On the other
hand, we may underestimate proposals for novel CDR where national
policymaking is in its infancy (even though countries would have little
incentive to develop concrete plans but exclude these from their com-
municated targets). Given these uncertainties, it remains important
to continuously track new developments and update estimates of the
CDR gap as national policies and targets are refined.
CDR entails many challenges for designing policy, supporting
innovation and ensuring sustainable, equitable and durable remov-
als. Our Analysis shows that scenarios meeting the Paris temperature
goal imply a very rapid scaleup of CDR and that governments are not
planning for this. A twofold strategy that limits our dependence on
CDR through rapid and deep emissions reductions, yet aggressively
supports and scales CDR implementation is not a contradiction but a
necessary pathway towards successful climate policy.
Online content
Any methods, additional references, Nature Portfolio reporting sum-
maries, source data, extended data, supplementary information,
acknowledgements, peer review information; details of author contri-
butions and competing interests; and statements of data and code avail-
ability are available at https://doi.org/10.1038/s41558-024-01984-6.
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2024

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Analysis
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Methods
Following the IPCC and State of CDR reports, we defined CDR as “Human
activities capturing CO2 from the atmosphere and storing it durably in
geological, land or ocean reservoirs, or in products. This includes
human enhancement of natural removal processes, but excludes
natural uptake not caused directly by human activities.”1,2 Important
characteristics of this definition are its unambiguous inclusion of both
conventional land-based sinks and emerging CDR methods, as well as
requirements for durability and direct human intervention19.
A wide array of CDR technologies have been developed, tested or
are in practice today60. In this Analysis, we follow ref. 2 and categorize
afforestation, reforestation, forest management, soil carbon sequestra-
tion, wetland restoration and durable harvested wood products as ‘con-
ventional CDR on land’. ‘Novel CDR’ comprises all other CDR methods,
such as biochar as well as those that store carbon in the lithosphere
including direct air carbon capture and storage (DACCS), bioenergy
carbon capture and storage (BECCS) and enhanced weathering.
Direct versus indirect anthropogenic CDR
Whereas novel CDR methods are solely the result of direct human inter-
vention, land can remove CO2 from the atmosphere through a combina-
tion of direct anthropogenic effects (such as land-use change, forest
harvest and regrowth), indirect anthropogenic effects (such as fertiliza-
tion because of elevated atmospheric CO2) and natural effects (such as
climate variability). These effects are impossible to disentangle through
observations but can be partitioned using earth system models61.
The different treatment of indirect anthropogenic effects and of man-
aged land concepts are the main reasons for the major discrepancy
between national inventories and global bookkeeping models used
in the IPCC assessment reports62,63.
To keep consistency with the IPCC definition of CDR, we con-
sidered CDR on land as only the net direct human-induced removal
component occurring in managed areas of forests and soils. (Note:
deforestation is human induced but is categorized as emissions, not
CDR, and is therefore excluded). Defining CDR in this way orients poli-
cymakers towards addressing those activities under their direct control
(for example, forest and soil management practices) and avoids claims
on CDR that result from global factors outside their direct control (for
example, the CO2-fertilization effect).
To evaluate current conventional CDR on land on this basis, we
started from the latest compilation of national LULUCF inventories39,
considering all negative fluxes from forest land and other land uses as
removals. A global ratio of direct to indirect anthropogenic removals
derived from ref. 19 was then applied to the forest land fluxes to remove
the indirect component. The resulting global and national levels of
current conventional CDR on land were then taken as the baseline for
any changes observed in the NDCs and long-term strategies (described
below). Where these documents describe an increase in conventional
CDR on land compared with the baseline inventory, we considered
this increase as representing direct removals only. Where a decrease
is described in the long-term strategies, we preserved the current ratio
of direct to indirect removals. The final analysis considered direct
anthropogenic removals only, as shown in Supplementary Fig. 2.
CDR in national 2030 mitigation pledges
Several assumptions need to be taken to extract CDR levels from NDCs.
First, with the aim of identifying quantifiable conventional CDR on land
and considering the frequent lack of LULUCF information in the NDCs,
we gathered as much official information as possible up to a cut-off
date of November 2023 (that is, COP28). This included not only NDCs,
which we prioritize, but also other relevant national submissions to the
UNFCCC where mitigation targets and information on activities and flux
disaggregation are usually included, such as long-term mid-century
strategies (for example, USA, Chile), National Communications (for
example, China, Japan, New Zealand), Biennial Update Reports (for
example, Peru) and Forest Reference Emission Levels (for example,
Malaysia, Peru, Mexico). Whenever available, we also considered other
national documents, such as climate strategies (for example, Norway,
Chile, Thailand, the Philippines, Mexico, Peru), GHG projections (for
example, Brazil) or assessments of national targets (for example, India).
We prioritized documents by ranking countries according to their
contribution to global emissions and removals, using the PRIMAP
Hist-CR database64 and ref. 39. We searched for this information in
111 of 195 countries reporting under the UNFCCC framework, exclud-
ing small island states, city states and countries with no or very low
land-use fluxes.
Second, we followed different strategies to extract information
from these documents and estimate the specific contribution of
LULUCF removals to national pledges, depending on the level of trans-
parency and information available for each country. As summarized in
Supplementary Fig. 1, countries can be categorized into three groups:
•
Group A: countries with the least amount of information
regarding their headline mitigation target and the contribution
of LULUCF. For these countries, we assumed that removals in
2030 remained consistent with the historic trend (2011–2020).
(n = 25, historic inventory-based gross removals (2011–2020) =
−0.38 GtCO2 yr−1, no additional CDR for 2030)
•
Group B1: countries with a specified LULUCF target in 2030 but
no information regarding the contribution of removals. We
scaled the LULUCF target to the historic ratio of emissions and
removals (2011–2020). (n = 55, historic inventory-based gross
removals = −3.45 GtCO2 yr−1, additional conditional CDR for
2030 = −0.22 GtCO2 yr−1)
•
Group B2: countries with a specified LULUCF target in 2030 and
with information on the specific contribution of removals. We
directly reported these removals in our analysis. (n = 31, historic
inventory-based gross removals (2011–2020) = −3.87 GtCO2 yr−1,
additional conditional CDR for 2030 = −0.33 GtCO2 yr−1).
It is relevant to note that the national extra removals (that is, CDR)
are presented here as the difference between committed removals in
2030 (un/conditional) and countries’ average removals for the previous
decade (2011–2020). This approach offers high temporal coherence
between countries’ emissions and mitigation commitments in 2030.
Historical averages of removals were based on an update (July
2023) of a compiled database of national GHG inventories obtained
from UNFCCC submissions39. Emissions were calculated as the sum of
all positive GHG fluxes detailed in ref. 39 (that is, forest, deforestation,
organic soils and other), while removals are the sum of all negative
fluxes. Most emissions come from deforestation and organic soils,
while most removals come from forests. The category ‘other’ is either a
removal or an emission, depending on the country as it includes other
non-forest land uses (croplands, grasslands, wetlands, settlements).
Since not all countries contribute similarly to global mitigation targets,
below we provide more insights for several key countries, with addi-
tional examples in Supplementary Information Section 1.
Brazil: There are several possible scenarios for Brazil’s LULUCF
commitments in 2030, but none of them are described in their latest
NDC (2022). One scenario is presented in the Low Carbon Agriculture
Programme (ABC and ABC+), but their targets are considered obsolete
(year 2014). We therefore used Brazil’s national mitigation projections
and mitigation options for 2030 and 2050 published by the Minis-
try of Science and Technology in 201765. This official report includes
land-use net emissions for its business-as-usual (BAU) trajectory (2030)
(298 MtCO2e) and two commitment scenarios based on two difference
prices for mitigation investment (270 and 189 MtCO2e as uncondi-
tional and conditional LULUCF emissions in 2030). Historical removals
(2011–2020) are about −400 MtCO2 yr−1, while the extra removals (that
is, CDR) under conditional commitments that we estimated in 2030

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Analysis
https://doi.org/10.1038/s41558-024-01984-6
are about −45 MtCO2 yr−1. Brazil is a Category B1 country (numerical
LULUCF target with unspecified removals).
Indonesia: Its 2022 NDC submission is highly informative on
LULUCF quantitative targets (−500 and −729 MtCO2e unconditional and
conditional committed emissions) and projected BAU (714 MtCO2e).
The NDC also describes a list of mitigation activities disaggregated
between emission avoidance and removals, to support their claims.
Historical removals (2011–2020) are about −370 MtCO2 yr−1, while
the extra removals (that is, CDR) under conditional commitments we
estimated in 2030 are about −165 MtCO2 yr−1. Indonesia is a Category
B2 country (numerical LULUCF target with specified removals).
China: The latest NDC includes the target to ‘increase forest stock
volume by around 6 billion cubic metres in 2030 from the 2005 level’,
which is not easily translated into a CO2 sink value. However, LULUCF
targets are better covered in the Third Biennial Update Report 3 (2018),
where forest sink projections are specified for 2030 as BAU (2030)
−410 MtCO2e (range: 390–430 MtCO2e), and two forest sink targets are
presented under two scenarios of action that preserve the same com-
mitment for forests sinks (−495 MtCO2e) (range: 470–520 MtCO2e). To
allow the comparison of the target with the LULUCF historical trend,
forest sink targets were then complemented by the average sink of
other non-forest land uses for the period 2011–2020, raising the com-
mitted sink to −806 MtCO2e yr−1 for 2030. Due to China’s current large
sink of about −1,135 MtCO2e (average 2011–2020), their LULUCF targets
for 2030 translated into a weakening of removals, that is, an increase
in net emissions (~326 MtCO2 yr−1), which markedly reduced the global
LULUCF sink commitments. China is a Category B2 country (numerical
LULUCF target with specified removals).
CDR in national 2050 mitigation pledges
To calculate CDR in national 2050 mitigation pledges, we relied on
information in the long-term strategies as analysed in refs. 13,66, read-
ing all submissions up to November 2023 (that is, COP28). We identi-
fied the subset of these that have quantified scenarios describing how
they will reach their stated climate objective (for example, net-zero
GHG emissions). Often, these scenarios are depicted in a figure or a
table, where the contribution of novel or conventional CDR on land is
included as a portion of the mitigation effort. If the long-term strategy
did not include such quantitative material, we assumed that any cur-
rent removals (that is, from conventional CDR on land) are sustained
until 2050. As in the NDCs, most countries describe the total LULUCF
flux in their scenarios, rather than providing a breakdown of emissions
and removals in this sector. We counted the entirety of these fluxes in
2050 as removals. In other words, we assumed zero deforestation. This
assumption is consistent with the text and framing of the long-term
strategies. For example, no countries describe deforestation in their
scenarios and several of them, such as Cambodia and Colombia, explic-
itly pledge zero deforestation. However, we acknowledge that it is a
simplification.
In the case of the European Union, we discarded all member-state
documents and instead relied on modelling studies performed by the
European Commission describing EU-wide pathways to net zero by the
mid-century67. While these were published before the United Kingdom
formally left the European Union, we continued to include the United
Kingdom’s long-term strategy separately.
Scenario selection and re-analysis
Our selection of IAM scenarios drew from the latest IPCC AR6 vetted
scenario database20. We used the C1 and C3 scenario categories, which
together are referred to as ‘below 2 °C scenarios’ in the main manu-
script. These scenarios could be considered as those most relevant
to, but not necessarily all consistent with, the Paris Agreement tem-
perature goal.
We used the scenario re-analysis provided in ref. 21 that splits emis-
sions and removals in the land-use sector. Their analysis was conducted
by running the OSCAR bookkeeping model using variables reported in
the AR6 scenario database, including forest land area, cropland area
and forestry activity, to evaluate the direct anthropogenic removals on
managed land. These scenario projections followed and extended the
experimental setup used for the 2021 Global Carbon Budget68.
Data availability
The data for this Analysis are available via Zenodo at https://doi.org/
10.5281/zenodo.10821849 (ref. 69). All raw and processed data are freely
accessible, except for complete national-level CDR estimates in 2030
(that is, from the NDCs and other national documents) which will be
made available upon reasonable request. Source data are provided
with this paper.
Code availability
The code for this Analysis is available via Zenodo at https://doi.org/
10.5281/zenodo.10821849 (ref. 69).
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Acknowledgements
This work was supported by the European Union ERC-2020-SyG
‘GENIE’ (951542) grant (W.F.L., J.C.M., G.N., T.G., M.J.G., Y.P., J.S.,
K.R.); the UK Natural Environment Research Council ‘CO2RE Hub’
(NE/V013106/1) grant (S.M.S.); the European Union Horizon 2020
‘ESM2025’ (101003536) and ‘RESCUE’ (101056939) grants (T.G.); the
German Federal Ministry of Education and Research ‘CDRSynTra’
(01LS2101A) (J.C.M., O.G.) and ‘ASMASYS’ (01LS2101A) grants (O.G.).
Author contributions
W.F.L., G.N., S.M.S., O.G., K.R. and J.C.M conceived the idea for
the paper. W.F.L., T.G., R.M.R.-C., G.G., M.J.G., C.M.P., Y.P., J.S., N.E.V.
and H.S. contributed to data gathering and the analysis. W.F.L.

Nature Climate Change
Analysis
https://doi.org/10.1038/s41558-024-01984-6
wrote the paper. All authors contributed to drafting, reviewing and
editing the paper.
Competing interests
The authors declare no competing interests.
Additional information
Supplementary information The online version contains supplementary
material available at https://doi.org/10.1038/s41558-024-01984-6.
Correspondence and requests for materials should be addressed to
William F. Lamb.
Peer review information Nature Climate Change thanks Andres
Clarens, Wim Carton and the other, anonymous, reviewer(s) for their
contribution to the peer review of this work.
Reprints and permissions information is available at
www.nature.com/reprints.

    Scientific Research Study Methods:

Answer: We evaluated CDR proposals based on a range of country-submitted reports to the UNFCCC. In the LULUCF sector, inventories are based on direct observations and hence cannot factor out ‘indirect anthropogenic effects’. Since this inflates apparent proposals for CDR when compared to scenario conventions, we discount these indirect effects to focus only on direct anthropogenic removals, consistent with the IPCC definition of CDR. We then added conventional removals to any national proposals for scaling novel CDR. Finally, we benchmarked the collective national proposals against CDR in a set of Paris Agreement-consistent integrated assessment scenarios, orienting our selection of scenarios to those with relatively moderate levels of CDR scaling — recognizing the existence of both sustainability constraints and limits to the pace of upscaling.