Blue carbon: A secret weapon in the fight against climate change?

As the world grapples with the urgent need to address climate change, the role of the ocean in carbon sequestration has come under the spotlight. The 2025 World Oceans Day and National Ocean Publicity Day, with the theme "Protecting the Marine Ecosystem for Harmonious Coexistence between Man and Nature", will be held on June 8, highlighting the crucial role of the ocean in global carbon neutrality and climate change mitigation.

The ocean, as the largest carbon sink on Earth, stores 50 times more carbon than the atmosphere and 20 times more than terrestrial ecosystems. It absorbs approximately one-third of the world's annual carbon dioxide emissions. Marine carbon sequestration, or "blue carbon," which relies on ecosystems such as mangroves, seagrass beds and salt marshes, plays a vital role in maintaining the Earth's carbon balance.

Pacific Island countries, with their vast ocean resources, hold a strategic position in the blue carbon realm. However, they are also highly vulnerable to the impacts of climate change, such as rising sea levels and extreme weather events, due to their small land areas and low-lying terrains.

Against this backdrop, China and Pacific Island countries have been strengthening cooperation in marine carbon sequestration. During the 2025 Shanghai International Carbon Neutrality Expo, which was held from June 5 to 7 with the theme "Towards a Carbon-Neutral Future", significant cooperation projects and technological achievements in the field of blue carbon were announced.

The shellfish and macroalgae aquaculture carbon sequestration project is highly groundbreaking. According to Dr. Yan Jinpei from the Third Institute of Oceanography, Ministry of Natural Resources, the annual carbon sink capacity of China's three major coastal blue carbon ecosystems is approximately 1.2688 to 3.0774 million tons of carbon dioxide. As the world's largest marine aquaculture nation – particularly dominated by macroalgae and shellfish farming – China's shellfish and macroalgae production accounts for about 85 percent of its total aquaculture output. It is estimated that by 2030, marine aquaculture in China will remove approximately 2.3 million tons of carbon from water bodies annually, with this figure expected to exceed 4 million tons by 2050. Macroalgae absorb carbon dioxide through photosynthesis and store carbon in the ocean.

Mr Mona Mato, the trade commissioner of Pacific Trade Invest China, emphasized the significance of these cooperation projects. "The collaboration with China in marine carbon sequestration is of great importance for Pacific Island countries. It not only helps them address the challenges of climate change but also promotes sustainable development in the region," he said.

Beyond project implementation, China is exploring market-oriented pathways for marine carbon sinks. Carbon trading has emerged as a potential economic model: The blue carbon development project can be categorized into five primary components: blue carbon resource identification, blue carbon methodology development, blue carbon monitoring and accounting, blue carbon verification and blue carbon trading.

Jane Ma, CFA charter holder and head of Investments at Pacific Trade Invest China, believes that the cooperation between China and Pacific island countries in blue carbon can serve as a replicable model for the global blue carbon economy. "By combining technological innovation, policy support, and community participation, we can create a win-win situation for both the environment and the economy," she said.

The economic value of the ocean is also on the rise. The Organization for Economic Co-operation and Development (OECD) predicts that by 2030, the economic value of the ocean will exceed $3 trillion, equivalent to the world's fifth-largest economy. This further underscores the importance of sustainable ocean development and the role of blue carbon in the global economy.

As China's Vice President Han Zheng is set to attend the United Nations Ocean Conference in Nice, France, from June 7 to 13 and visit Spain, the international community's attention on ocean issues, including marine carbon sequestration, is expected to increase. The cooperation between China and Pacific island countries in blue carbon is not only a regional effort but also a contribution to global climate governance, demonstrating the potential of blue carbon as a powerful tool in the fight against climate change.