AKU: An African Journal of Contemporary Research

This study examines carbon emissions, biodiversity decline, and sustainable development across African economies using panel data, focusing on how CO2 emissions, GDP, and renewable energy jointly shape an Environmental Sustainability Index (ESI). Grounded in the environmental Kuznets curve (EKC) hypothesis and ecological modernisation theory, the study employs fixed effects, random effects, and system GMM estimators. Because the ESI combines a biodiversity sub-index with an inverted CO2-intensity sub-index, the mechanical correlation this creates with CO2 as a regressor is explicitly diagnosed and addressed through a robustness specification using a CO2-free biodiversity-only outcome. CO2 emissions are significantly associated with lower sustainability, a relationship that survives this robustness check. Renewable energy consumption raises sustainability scores. GDP shows a significant quadratic relationship with ESI that, once the direction of variable coding is made explicit, is shown to be fully consistent with the conventional inverted-U EKC rather than a departure from it. Sub-group analysis shows the emissions-sustainability relationship is markedly steeper in oil-producing and industrialising economies than in agrarian and renewable-dependent ones. Full regression tables, standard errors, instrument counts, and diagnostics are reported, and causal language is calibrated to what the design supports. The study contributes by integrating biodiversity into macroeconomic sustainability analysis for Africa while transparently addressing the resulting endogeneity concern, and recommends renewable investment, stronger environmental regulation, and typology-differentiated policy.

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