Abstract
Urban carbon emissions are a major driver of climate change, which makes sustainable decarbonization strategies essential. Urban greenery is a promising nature-based solution, but its long-term potential for carbon sequestration is often underestimated because research tends to focus on short-term benefits such as aesthetics, cooling effects, and energy savings. To address this gap, we conducted a systematic literature review of 175 publications (with no restriction on publication year) to examine urban greenery's role in decarbonization across three dimensions, i.e., mechanisms (carbon fixation and storage processes), technologies (methods for quantifying carbon fluxes), and implementation (multi-scale interventions). The quantitative evidence shows substantial but variable impacts. Some green spaces can sequester thousands of tons of CO2 annually, and in a few cases, offset up to about 7% of municipal emissions, while green roofs sequester on average about 0.3–0.4 kg CO2 m−2. Progress is nevertheless limited by a lack of dynamic lifecycle assessments, fragmented data, and a gap between design optimizations and real-world implementation. We propose that future efforts should develop integrated frameworks that combine dynamic life-cycle inventories, multi-source data fusion, and AI-enhanced cross-scale modeling. Based on policy-public collaborative governance pathway, implementing scalable guidelines and toolkits that span building, neighborhood, and urban scales will help translate these strategies into context-specific actions that advance climate resilience and equitable urban futures.