Biological and geological carbon sequestration monitoring techniques: a review

Carbon sequestration captures, stores, and reduces CO₂ emissions across environmental ecosystems. It encompasses two primary pathways: biological processes in terrestrial ecosystems and geological storage in underground formations. Researchers and policymakers have focused on carbon sequestration monitoring to confirm storage effectiveness and maintain long-term retention. Some of the main reasons behind monitoring importance are regulatory compliance, carbon credit verification, and leakage detection. Despite its importance, critical gaps include limited definitional clarity for carbon sequestration monitoring, insufficient validation reporting in 57% of studies, and geographical research differences concentrated in North America. To provide a comprehensive understanding of carbon sequestration monitoring, a systematic literature review was conducted using the PRISMA framework, evaluating 56 scientific publications to assess monitoring techniques across both pathways. The review analyzed definitions of carbon sequestration and carbon sequestration monitoring from the literature, identifying key components for each, and developed a simple and broad definition. It also identified monitoring techniques and established a hierarchical classification system, identifying four primary categories for biological sequestration and six for geological sequestration. The review revealed distinct advantages and disadvantages across different monitoring categories. Remote sensing offers an advantage in spatial coverage but faces classification challenges; field measurements provide high accuracy but remain labor-intensive; machine learning shows promising capabilities despite accuracy limitations; and integrated techniques offer a comprehensive assessment despite increased complexity.