Environmental federalism and multi-level governance coordination in Southeast Asia: A comparative empirical analysis of five ASEAN economies

Environmental federalism, the allocation of environmental regulatory authority across national, provincial, and local government tiers, has become a pressing governance challenge in Southeast Asia amid escalating climate vulnerability, transboundary environmental pressures, and uneven institutional development. This study conducts a comparative empirical analysis of multi-level environmental governance arrangements in Indonesia, Malaysia, the Philippines, Thailand, and Vietnam over the period 2019 to 2024. Employing a mixed methods design that integrates comparative institutional analysis with quantitative governance indicators drawn from the Environmental Performance Index, the World Bank Worldwide Governance Indicators, and climate policy databases, the study examines decentralisation structures, intergovernmental coordination mechanisms, and governance performance across five structurally diverse national contexts. The findings reveal substantial cross-country variation in regulatory authority distribution, administrative capacity, and environmental governance effectiveness. Recurrent challenges include jurisdictional overlap, institutional fragmentation, uneven sub-national administrative capacity, and coordination failures in managing transboundary problems such as haze pollution and climate-related risks. Critically, governance outcomes are found to be more strongly associated with the quality of institutional coordination and operational implementation capacity than with the degree of centralisation or decentralisation per se. The study argues for asymmetric decentralisation approaches calibrated to local institutional readiness, and advocates for adaptive, multi-stakeholder governance frameworks capable of bridging administrative boundaries. The findings carry practical implications for environmental policymakers, sustainability managers, and ESG strategists operating within Southeast Asia's complex and fragmented regulatory landscape.