Carbon Sequestration as a Framework for Urban Facility Planning in Benin Metropolis, Nigeria

Cities contribute heavily to climate change but also hold solutions. This study examines how urban facilities in Benin Metropolis, Nigeria, can act as carbon sinks. A systematic review and meta-analysis, guided by PRISMA protocols, were conducted. Evidence was drawn from global, regional, and Nigerian studies on five facility types (green infrastructure, public buildings, transport, waste, and water systems). Findings show that green infrastructure and waste management are the most immediate and cost-effective strategies. They sequester carbon while tackling urgent urban problems like flooding, sanitation, and heat stress. In the medium to long term, mass timber construction, bio-based materials, electrified transport, and constructed wetlands offer transformative benefits. The study develops a framework combining Urban Political Ecology, the Circular Bioeconomy, and Sustainable Urban Development Theory. This highlights that carbon sequestration is not only technical but also political and social. Governance, justice, and local participation shape outcomes as much as technology. For Benin Metropolis, ecological opportunities exist, but governance weaknesses, outdated codes (building code, urban planning regulations, and energy and transport standard), and limited finance are major barriers. The study concludes that carbon sequestration should become a central principle of urban facility planning. Embedding it into facilities can shift Benin Metropolis from a net carbon source to a carbon sink. This approach also aligns with Nigeria’s Climate Change Act (2021) and global sustainability goals.