PEMSEA Regional Methodology for Blue Carbon Project Accounting

A Harmonized Guide for Estimating Carbon Stocks, Sequestration, and GHG Reductions in Coastal Ecosystems

Differences in measurement methods, carbon pool inclusion, and monitoring frameworks have made blue carbon projects in East Asia hard to compare. PEMSEA’s Regional Methodology addresses this with a single accounting framework for mangroves, seagrasses, and salt marshes. It is designed to be compatible with national greenhouse gas inventories and technically aligned with voluntary carbon credit certification requirements.

The Main Methodology sets out project eligibility and additionality, boundaries and stratification, baseline and project scenarios, uncertainty management, a tiering system, leakage, permanence and risk management, and monitoring, reporting, and verification. Five technical annexes provide the field and analytical detail:

• Annex A – Mangrove Ecosystems: carbon stock and sequestration assessment methods
• Annex B – Seagrass Ecosystems: carbon stock and sequestration assessment methods
• Annex C – Salt Marsh Ecosystems: carbon stock and sequestration assessment methods
• Annex D – Mapping Blue Carbon Ecosystems: remote sensing, validation, and change detection
• Annex E – Monitoring Environmental Parameters: the environmental conditions that influence blue carbon ecosystems

The methodology was prepared under the guidance of the Blue Carbon Technical Working Group of the EAS Partnership Council, with contributions from experts across the region. It is intended for project developers, national agencies, researchers, and verifiers working to bring high-integrity blue carbon projects to market.

The Korea Maritime Institute (KMI) and Partnerships in Environmental Management for the Seas of East Asia (PEMSEA) convened the International Seminar on Blue Carbon Ecosystem Values in Busan, Republic of Korea. The seminar gathered representatives from six East Asian countries, academic institutions, and regional partners to validate enhancements to the Regional Blue Carbon Accounting Protocol (RBCAP), review biodiversity accounting and crediting approaches, and define PEMSEA’s role in governance, verification, and market development. Key outcomes included expert recommendations to strengthen the RBCAP, shared insights on biodiversity crediting pathways, and a clearer vision of PEMSEA’s added value as a regional platform for advancing blue carbon and biodiversity markets.

The 2026 PEMSEA Network of Local Governments for Sustainable Coastal Development (PNLG) and PEMSEA Network of Learning Centers (PNLC) Joint Learning Forum, themed “Empowering Coastal Cities for a Blue Future,” was organized by the PNLG and PNLC in collaboration with the Korea Maritime Institute (KMI), the Korea Institute of Ocean Science and Technology (KIOST), Coastal 500, and the PEMSEA Resource Facility. The Forum was hosted by the Metropolitan City of Busan, Republic of Korea. The Joint Learning Forum took place on 8 September 2026 at Paradise Hotel Busan as part of the 2026 PNLG Annual Forum (8-10 September 2026). It featured two panel discussions: Local Pathways for Blue Carbon and Nature-Based Solutions, and Capitalizing on Coasts: Financing and Innovating Local Blue Economies.

The document contains the proceedings from the PNLC Executive Committee (EC) held 9 September 2026 in Busan, Republic of Korea.

The meeting was participated in by the President and Vice-President of the PNLC, the PEMSEA Executive Director, and the PNLC Secretariat from IPB and the PEMSEA Resource Facility. The agenda included:

• Workplan 2026-2027
• Updates on PNLC Expenditure and Financial Sustainability

Other Business:

• PRF Project Updates
• 2027 EAS Congress
• ICM Report
• Nature-based Solutions Capacity-building

• PEMSEA Blue Carbon Program Updates

   

September connected regional decisions with local action—from a new declaration in Busan to community-led work across the region.

In Busan, the 2026 PNLG General Assembly adopted the Busan Declaration on Promoting Local Coastal Resilience and Sustainable Blue Economy and welcomed Atauro Island, Timor-Leste, as the Network’s newest member. Meanwhile, PEMSEA Founder Dr. Chua Tia-Eng returned to the PEMSEA Resource Facility for a discussion with colleagues on  PEMSEA’s history, lessons, and continuing role in advancing sustainable coastal and ocean governance.

PEMSEA project updates include the GEF/UNDP/ASEAN IRBM Project advanced planning for food and biodegradable waste management in the Pasac-Guagua Watershed, while the PRICELESS Project brought stakeholders together in Regions 3 and 4A to tackle challenges and priorities for the Philippine Rise.

In the Philippines and Timor-Leste, MEP partners under the MOF/PEMSEA Marine Plastics ODA Project mobilized communities, schools, government agencies and civil society organizations for International Coastal Cleanup activities, turning awareness of marine plastic pollution into action on the ground.