Long-term national climate strategies bet on forests and soils to reach net-zero

The Paris Agreement's net-zero ambition necessitates countries to address the practical and policy aspects of Carbon Dioxide Removal (CDR) to meet national climate targets. While 124 countries have committed to net-zero emissions, explicit CDR strategies remain scarce. This research systematically analyzes CDR integration within 41 national long-term climate strategies (LT-LEDS) submitted to the UNFCCC before 2022, representing 58% of global 2019 greenhouse gas emissions and 74% of global GDP. Global assessments of CDR have sparked debate on method credibility and sustainability at scale, but national-level analysis is needed to understand deployment, policy, and governance challenges. CDR methods—categorized here as nature-based (forests, soils, coastal blue carbon) and engineered (BECCS, DACCS)—vary in potential and limitations (cost, readiness, permanence, societal acceptance). National policies must address these, transitioning from research to full integration within policy mechanisms. The urgent need to scale up CDR methods by 2050 to meet Paris Agreement targets necessitates examining national net-negative targets and international transfer mechanisms. National governments have a decisive role in CDR realization, but comparative studies remain limited. This study analyzes LT-LEDS to examine target specifications, employed CDR methods, quantified CDR relative to residual emissions, and feasibility/cooperation statements, identifying two key challenges: limitations of land-use and geological storage, and the need for international cooperation. The UNFCCC's reporting requirements on LT-LEDS need urgent strengthening.

Existing literature highlights the growing importance of CDR in achieving net-zero targets and the need for comprehensive policy frameworks to facilitate its deployment. Studies such as Schenuit et al. (2021) and Buylova et al. (2021) have examined CDR policy developments and the role of CDR in national strategies, respectively, but often focus on smaller samples. Mace et al. (2021) analyze governance gaps in large-scale CDR, while Iyer et al. (2021) investigate the role of CDR in net-zero pledges. The analysis also touches on the debates surrounding the classification of CDR methods, distinguishing between 'nature-based' and 'engineered' approaches. Other relevant works explore the economic and technological aspects of CDR, emphasizing challenges related to cost, scalability, and permanence (Fuss et al., 2014, 2018; Smith et al., 2016). The role of international cooperation and carbon markets in facilitating CDR deployment has also been a subject of extensive research, addressing concerns about equity and effectiveness (Honegger et al., 2021; Kachi et al., 2019). This study builds upon this existing body of knowledge by providing a comprehensive analysis of CDR in a substantially larger dataset of national climate strategies.

The analysis encompassed all English-language LT-LEDS published by the UNFCCC Secretariat before January 1, 2022, plus Estonia's EU long-term strategy (Fig. 1). A total of 3885 pages were analyzed using NVivo software. Analytical categories were developed using both inductive and deductive coding, incorporating insights from the existing literature on CDR (Azungah, 2018). The coding process involved meticulous review and cross-checking by the authors to ensure accuracy and avoid bias. The initial codes were categorized into broader themes, and these were further refined iteratively until code saturation was achieved. CDR methods were categorized as 'nature-based' (forests, soils, coastal blue carbon, enhanced weathering) and 'engineered' (BECCS, DACCS). The analysis included the examination of long-term targets (headline target, sectoral and GHG coverage, use of international offsets, etc.), quantified CDR in 2050, residual emissions, and qualitative considerations/speculative mentions of CDR methods. The 'sink status' (net balance of land-use carbon sink historically and in future projections) was also recorded. Data on 2050 CDR quantification was obtained from the scenarios that best reflected each national strategy's position. Additional details on coding, data sources and criteria are provided in Supplementary Data 1, 2 and 3.

The study reveals a significant reliance on nature-based CDR, particularly enhancing forest and soil carbon sinks, across the analyzed LT-LEDS. While forests are the most quantified and advocated method, their long-term viability faces limitations. Only 20 strategies quantified residual emissions in 2050, with 13 primarily relying on forest carbon to compensate, raising concerns about the long-term sustainability and reversibility of this approach. The analysis highlights ambiguity in long-term targets, varying in their definition of net-zero (CO2 only, all GHGs, sectoral coverage, use of international offsets) which can affect CDR demand calculations. The study found that engineered CDR methods, such as BECCS and DACCS, feature less prominently and their consideration often remains speculative, particularly in strategies from countries outside the Global North. The feasibility of CDR methods is also challenged by land-use limitations (e.g., limited land availability for afforestation, risk of wildfire, saturation of carbon sinks) and geological storage capacity for engineered-CDR. Several countries acknowledge these limitations, highlighting the need for future research and innovations in engineered CDR. The analysis also uncovers a growing awareness of the need for international cooperation on CDR to address national constraints and facilitate cross-border transfers of removals (e.g., for CO2 storage or deployment of DACCS). This cooperation is envisioned through bilateral partnerships, international carbon markets, and mechanisms under Article 6 of the Paris Agreement, suggesting that net-zero planning is becoming increasingly interconnected.

This study's findings highlight several critical aspects of national net-zero planning and the integration of CDR. The dependence on forests and soils as the primary CDR mechanism is concerning given their limitations in terms of scalability, permanence, and vulnerability to disturbances. The ambiguity in long-term targets underscores the need for a shared definition of national net-zero to ensure clarity and consistency in CDR planning. The lack of quantification of residual emissions in many strategies indicates that many countries struggle to fully integrate CDR into their modelling frameworks, hindering comprehensive evaluation. The identified need for international cooperation highlights the interconnected nature of national net-zero targets and the potential for future collaborations in CDR deployment and carbon market mechanisms. The limited consideration of engineered CDR strategies underlines the need for further research and development to explore their potential for long-term and sustainable carbon removal. Achieving and maintaining net-zero requires sustained emission reductions and a diversified approach to CDR, with engineered methods potentially playing a crucial role in achieving net-negative emissions in the long term.

This research emphasizes the crucial role of CDR in achieving national net-zero targets and highlights significant limitations in current national approaches. The reliance on forests and soils, while understandable given existing policy mechanisms, presents risks due to their limitations and reversibility. The study advocates for improved reporting requirements by the UNFCCC, including a standardized definition of national net-zero, comprehensive quantification of residual emissions and CDR, and explicit consideration of national constraints and the potential for international cooperation. Future research should explore the equitable distribution of CDR obligations and deepen the analysis of the implications of international carbon markets for national net-zero strategies. Integrating a clearer understanding of long-term CDR needs into near-term policy cycles will help to mobilize CDR and ensure more ambitious emission reduction targets.

This analysis is limited by the availability of English-language LT-LEDS submitted to the UNFCCC before 2022. The sample may not fully represent the global diversity of national climate strategies and could introduce selection bias. The heterogeneity of LT-LEDS in terms of depth and breadth of analysis presented challenges in standardization of coding and interpretation. Uncertainties associated with the quantification of CDR methods, particularly nature-based approaches, might influence the interpretation of results. Finally, the study focuses primarily on biophysical and economic aspects of feasibility, limiting the consideration of socio-political factors that can significantly affect CDR deployment.