Carbon Sequestration Potential of Urban Green Infrastructure

Abstract

Urban green infrastructure (UGI) has gained recognition as a viable strategy for offsetting municipal carbon emissions, yet comprehensive lifecycle assessments remain scarce for cities in the Global South. This review synthesizes lifecycle carbon analyses of five UGI typologies   urban forests, street trees, green roofs, bioswales, and urban wetlands   across five tropical megacities: Mumbai, Jakarta, Manila, São Paulo, and Lagos. Drawing on 78 peer-reviewed studies published between 2010 and 2024, we applied a cradle-to-grave carbon accounting framework spanning a 50-year time horizon, incorporating IPCC AR6 emission factors for embodied carbon in construction materials, maintenance operations, and end-of-life disposal. Our results indicate that urban forests yield the highest net carbon balance (322 t C ha⁻¹ over 50 years), while extensive green roofs exhibit a near-neutral or slightly negative net balance (−1 t C ha⁻¹) when embodied carbon in substrate and waterproofing membranes is included. Cross-city comparisons reveal that sequestration rates vary by a factor of two, driven primarily by differences in species composition, precipitation regimes, and maintenance intensity. These findings underscore the need for city-specific lifecycle inventories when planning UGI investments and suggest that urban forests and bioswales should be prioritized over engineered systems in tropical contexts where land availability permits.