Promising Words, Evaluating Actions: Assessing Carbon Dioxide Removal in National Net Zero Plans

Smith, Harry (2025) Promising Words, Evaluating Actions: Assessing Carbon Dioxide Removal in National Net Zero Plans. Doctoral thesis, University of East Anglia.

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Abstract

Recent climate policy efforts are shaped by two connected trends, the rise of national net zero targets as the organising principle of climate policy, and the increasing recognition that Carbon Dioxide Removal (CDR) is unavoidable to reach the goals of the Paris Agreement, avoiding the worsts of climate change (Babiker et al., 2022). Net zero targets, by definition, require the deployment of CDR. National governments, however, have only recently engaged with the need for CDR to compensate for residual hard-to-abate emissions across their economies.

This thesis serves to address what is a key gap in climate policy research, the planning of national entities towards deploying CDR (Schenuit et al., 2021). To address this gap, this thesis analyses one of the main reporting provisions in the Paris Agreement, long-term low emission development strategies (LT-LEDS) and similar long-term strategies (LTS). LT-LEDS are overlooked in climate policy research to date, given the more prominent role of the shorter-term Nationally Determined Contributions (NDCs) in the Paris Agreement, and the need to align NDCs with the 2030 benchmarks mainstreamed in the Intergovernmental Panel on Climate Change’s (IPCC’s) Assessment Reports (Den Elzen et al., 2022). LTLEDS, by contrast, given their focus on the mid-century, and the more prominent role of CDR to compensate for residual hard-to-abate emissions as a country approaches net zero, more readily communicate the role of CDR in decarbonisation. LT-LEDS, however, have only recently reached a critical mass, whereby they cover the majority of global emissions and global economic activity, with submissions from 74 countries.

Using a consistent methodology and inductive and deductive coding, this thesis analyses the contents of LT-LEDS and similar LTS, and the scenarios and pathways detailed therein. Assessing the inclusion of CDR methods in scenarios or pathways, and in text, across 41 strategies, reveals a reliance upon nature-based methods, notably forest and soil carbon sinks. National government’s simultaneously stress the risks of relying upon these methods, such as the reversal risks to forests from wildfires, pests, and disease. Assessing the positive emissions that remain at the point of net zero, so called ‘residual emissions’, across a larger sample of 71 LTS, reveals that residual emissions are considerable in size. As a proportion of peak emissions, residual emissions average 21% for Annex I countries, and upwards of 52% in specific cases. These emissions are commonly considered ‘hard-to-abate’, stressing the technical and political complexities to their abatement, meaning they may be best indirectly mitigated through CDR, as opposed to directly abated at source (Babiker et al., 2022). Residual emissions therefore serve as the basis for the deployment of CDR. High residual emission scenarios, show how some countries may retain or expand their fossil fuel production and use, using more CDR or international offsets to achieve net zero, substantiating concerns of mitigation deterrence. By sector, agriculture represents the largest contributor to total residual emissions and the sector with the least relative ambition compared with current emissions. The coding of supporting rationales, detailing why an emission source is considered hard-to-abate or residual, reveals many countries treat residual emissions as an inevitability, overlooking agriculture and emphasising emissions from industry.

LT-LEDS, however, provide a broad overview of climate policy efforts, not detailed policies. They reflect largely promises of decarbonisation, as opposed to concrete actions. This thesis therefore evaluates a national case study where a national strategy has led to advanced policies and plans for CDR, that of the United Kingdom (UK). Through 25 interviews with experts active in CDR policymaking, this thesis identifies a desire for greater government intervention, with calls for the UK government to take a more active role in stimulating market demand, overseeing the sector, and governing the standards through which projects are assessed and credited. Participants were sceptical of the voluntary carbon market (VCM), looking towards government to stimulate demand in addition to the government’s current emphasis on ensuring supply. Participants welcomed greater government oversight, via, for example, the planned government monitoring, reporting and verification standard. These interviews demonstrate the challenge of CDR policymaking, including how concerns towards the role of CDR reflect wider debates in climate policy, such as the need for net-negative emission targets as an extension of net zero ambitions, given the seeming inevitability of temperature overshoot.

Combined this thesis demonstrates that CDR is no longer a debate limited to CDR’s role in scenarios assessed by the IPCC (Fuss et al., 2014). Rather CDR has become an active part of the debate that animates climate policy, and a key feature of the visions of net zero laid out in LTS. In doing so CDR presents new challenges to national governments, such as the extent and reliance upon CDR, and the policies through which CDR is incentivised. CDR therefore brings new concepts to the forefront of climate governance, such as residual emissions.

This thesis ends by setting out future avenues for research, including the prospect of separate targets for CDR and emissions elsewhere in an economy, as a means to reduce the likelihood of high residual emission scenario. Research efforts should similarly be made to explore the means through which residual emissions in agriculture can be further reduced, given their emphasis in scenarios presented in LTS. Further case studies of CDR policymaking are also needed, particularly how government policies are incorporating early efforts to scale CDR through the VCM and the prospect of net-negative emissions.

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Science > School of Environmental Sciences
Depositing User:	Kitty Laine
Date Deposited:	04 Nov 2025 11:53
Last Modified:	04 Nov 2025 11:53
URI:	https://ueaeprints.uea.ac.uk/id/eprint/100887
DOI:

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