Linking spatial convergence and circular economy transitions: evidence from waste-sector emissions in Sub-Saharan Africa

Inefficient waste management across Sub-Saharan Africa contributes substantially to greenhouse gas emissions, disrupting ecological nutrient cycles and accelerating environmental degradation in rapidly expanding urban peripheries. This study investigates spatial patterns, regional trends, and convergence in waste-sector CO₂-equivalent emissions, adjusted for organic waste fractions, across Kenya, Uganda, Tanzania, Ghana, and Nigeria from 2014 to 2023. The analysis highlights the interlinkages between waste management practices, emission intensities, and transitions toward a circular economy. Spatial dependence was examined using Moran’s I statistics and spatial lag regressions, while convergence was assessed through σ-variation, unconditional β-regression, and the Phillips–Sul (2007) club convergence approach. A life-cycle assessment conducted in OpenLCA with the ReCiPe 2016 method simulated the potential emission reductions from anaerobic co-digestion of organic wastes. Ecological network mapping was performed using the enaR package in R. Spatial analysis indicated significant clustering of waste-sector emissions (Moran’s I = 0.42, p < 0.01), highlighting emission hotspots in East Africa. Mean emission intensity was 0.97 t CO₂-eq per tonne of waste, with σ-dispersion declining from 0.26 in 2014 to 0.23 in 2023. Convergence was strongest among West African countries, particularly Ghana and Nigeria. The findings demonstrate that anaerobic digestion can accelerate the convergence of emissions and restore nutrient cycles, thereby reducing soil erosion and biodiversity loss. Coordinated regional policies promoting shared infrastructure for digestion can reshape emission clusters and strengthen nature-based resilience in African urban ecosystems.