Mangrove and Seagrass Blue Carbon Stocks and Fluxes Across ASEAN: A Dual-Framework Assessment of Soil Carbon Dynamics and Policy Implications

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🔬研究者:Provides a novel dual-framework methodology for blue carbon assessment with methane offsets, applicable to other coastal regions.

🏢実務担当者:Offers country-specific carbon balance sheets and investment guidance for high-integrity blue carbon projects in ASEAN.

🏛政策担当者:Demonstrates how inclusion of methane offsets affects net climate benefit estimates, informing NDC strategies and blue carbon policy design.

Abstract The Association of Southeast Asian Nations (ASEAN) region contains approximately one-third of the world’s mangrove forests and extensive seagrass meadows, making it a globally significant reservoir of coastal “blue carbon.” Yet these ecosystems face increasing pressure from land-use change and climate-driven stressors, raising concerns about the potential release of long-stored soil and sediment carbon. This study provides the first harmonized, region-wide assessment of blue carbon in soil stocks and fluxes across all 10 coastal ASEAN member states (Laos, as a landlocked country, does not support mangrove or seagrass ecosystems and is excluded from quantitative accounting) using a dual-framework approach. We integrate a probabilistic Net Ecosystem Carbon Balance (NECB) model—incorporating geomorphology- and salinity-stratified methane (CH₄) offsets—with a National Inventory method aligned with IPCC Tier 1 guidelines. Mangrove and seagrass ecosystems in ASEAN cover approximately 7.26 million ha, storing an estimated 853 Mt C in coastal soils. The Inventory assessment indicates a Net Climate Benefit of 44.6 Mt CO₂e yr⁻¹, derived from gross sequestration minus emissions from anthropogenic disturbance. In contrast, the NECB model yields a more conservative median sink of 5.5 Tg C yr⁻¹ (95% CI: 3.8–7.1 Tg C yr⁻¹), reflecting substantial methane emissions in deltaic systems. Oceanic/Fringing systems exhibit low methane penalties (< 15%), whereas Deltaic/Estuarine systems show high offsets (50–80%), often negating much of the carbon burial. These findings reveal strong but spatially heterogeneous climate-mitigation potential across the region. By providing country-specific carbon balance sheets and quantifying the divergence between policy-based and biophysical estimates, this study offers a scientific foundation for strengthening Nationally Determined Contributions (NDCs) and guiding high-integrity blue carbon investment in ASEAN.

• openalex https://doi.org/10.1007/s13157-026-02083-2first seen 2026-06-17 05:58:32 · last seen 2026-06-17 07:14:21