A bibliometric analysis of carbon dioxide removal research in the decade after the Paris Agreement

The Paris Agreement (2015) shifted global climate policy toward net-zero emissions, requiring both deep decarbonization and large-scale carbon dioxide removal (CDR) to neutralise residual emissions from hard-to-abate sectors. Research has developed along two largely separate streams: engineered removal (BECCS, DACCS, biochar, enhanced weathering) and nature-based solutions (afforestation, soil carbon sequestration). This study maps CDR research, as framed within climate-policy discourse, between 2016 and 2025, using 4281 records from the Web of Science Core Collection analysed with VOSviewer and Bibliometrix and screened following PRISMA 2020 guidelines. Output accelerated sharply after 2019, coinciding with the consolidation of net-zero targets. Network analysis identifies four thematic clusters (modularity Q = 0.19, exceeding a degree-preserving null model by 65 standard deviations): engineered removal, nature-based removal, soil-carbon science, and a CDR-policy core. The field is thematically structured but not globally siloed: most keyword co-occurrence links (54%) are cross-cluster and every cluster’s external-internal index is positive. Fragmentation is instead localised—the direct link between the engineered and nature-based clusters is the weakest coupling (10.3% of link weight), the two pillars connecting mainly indirectly through the soil-carbon and policy clusters. Thematic evolution runs from policy framing (2016–2019) to BECCS and neutrality themes (2020–2022) and to biochar and nature-based removal (2023–2025). Publication output is dominated by China and the United States, while the United Kingdom acts as the principal international broker. These findings indicate that the main integration deficit lies at the engineered-ecological interface, where targeted cross-disciplinary work would most directly strengthen the evidence base for net-zero pathways.