Blue carbon ecosystems (BCEs), such as mangroves, seagrasses, and salt marshes, play a crucial role in mitigating climate change by sequestering large amounts of carbon dioxide from the atmosphere. Blue carbon methodology, as significant tools for assessing the carbon sequestrating capacities of BCEs, plays a crucial role in ocean-based climate change mitigation.
In the globe context, blue carbon methodologies have been employed in the Clean Development Mechanism (CDM) and the Verified Carbon Standard (VCS) in existing Blue Carbon Projects. Since 2020, we have developed national methodologies for mangroves, saltmarshes, and seagrass beds in China, and applied them in domestic blue carbon markets. Compare to the existing global blue carbon methodologies, these methodologies in China have several distinctive features: 1) These methodologies are centered around the current practices of coastal wetland restoration and management in China, addressing scenarios such as mangrove planting, coastal wetland restoration, BCE reconstruction, restoring ponds to wetlands, and controlling invasive Spartina alterniflora by replanting native plants. These scenarios demonstrate the necessity and additional value of the Blue Carbon Project. 2) In the carbon sequestration accounting, the quantification of the key carbon sequestration processes in the whole carbon cycling is standardized and considered in the monitoring plans. Characteristic parameters, e.g., net primary production of typical vegetation types, the sediment organic carbon accumulation rates of different landform types, and the organic carbon content in seagrass water volume, are obtained from China’s BCEs monitoring network or assigned default values, which significantly increases the implementation of China’s Blue Carbon Projects and enhances feasibility. 3) These methodologies focus on ecosystem service, simplify the review process for projects with significant natural conservation value, and encourage financing of Blue Carbon Projects that integrate biodiversity conservation and sustainable development.
 

coastal wetlands, blue carbon, carbon cycling, carbon trading mechanism, ecosystem function