2021年7月22日，清华大学公共管理学院博士后杨越，清华大学公共管理学院长聘副教授、CIDEG主任陈玲在China Daily 上发表专题文章Blue solution，阐述了在双碳背景下，基于海洋碳库的解决方案的底层逻辑应遵循的基本路径了。“清华大学CIDEG”特将原文转载如下，以飨读者。

Blue solution

The carbon sink capacity of the oceans needs to be enhanced to help control emissions

As countries chase carbon peaking and neutrality goals, tapping the potential of the oceans for carbon sequestration－the process in which carbon dioxide is removed from the atmosphere－and their carbon sink capacity are bound to become a priority and therefore the next investment hotspot for climate-related financial capital.

Carbon pools have the capacity to store or release carbon, while carbon sinks are natural systems viewed in terms of their ability to absorb carbon dioxide from the atmosphere. The oceans are the biggest carbon pools in the Earth's ecological system, and the key to maintaining the carbon balance as they absorb nearly 30 percent of global carbon emissions and sequestrate nearly 55 percent of carbon emissions each year.

The ocean carbon pools are usually referred to as the "blue carbon pools" to distinguish them from the "green carbon pools" formed by the Earth's terrestrial ecosystems such as forests, grasslands and farmlands.

Climate change mitigation options based on ocean carbon pools should prioritize two areas－enhancing their capacity as ocean sinks and lowering the risk of them becoming a source of carbon emissions.

One way is to absorb carbon dioxide by adding minerals into certain sea areas to promote the growth of phytoplankton and algae. Another measure is to make the best of the marine ecosystem's own dynamics. The productivity of the ocean carbon pools can be increased if we solve the supply-demand mismatch of nutritive salt, inorganic carbon and dissolved oxygen at various marine layers.

For instance, artificial upwelling, the transporting of nutrient-rich water at the ocean's bottom to the euphotic zone－the upper layer of the oceans where there is enough light for the process of photosynthesis－and promoting the growth of phytoplankton and algae, which has been proposed by Chinese scientists, has been included in the Intergovernmental Panel on Climate Change's Special Report on Ocean and Cryosphere in a Changing Climate.

Despite their known benefits, around 60 percent of marine ecosystems are being damaged or degraded, resulting in the carbon sink capacity of the oceans continuing to decline, causing sizable economic, environmental and ecological losses, and, worse still, increasing the risk of the oceans turning into sources of carbon emissions. That will bring additional and unpredictable challenges to global climate governance.

The strategy for lowering the risk mainly focuses on how to reduce and repair the damage, caused by human activity to the marine ecosystems. To start with, we should significantly reduce the amount of land fertilizer and nutritive salt that reaches water bodies; avoid the intensification of respiration caused by offshore waters eutrophication－excessive richness of nutrients due to runoff from the land that causes a dense growth of plant life and death of animal life from lack of oxygen－and prevent nutritive salt from stimulating marine micro-organisms to degrade more organic matter a process that releases carbon dioxide into the air. Second, we should conserve and restore the blue carbon ecosystems.

The conservation and restoration of blue carbon ecosystems not only increases the capacity of the ocean carbon pools for carbon sequestration and ability to act as carbon sinks, but also provides essential ecological services including resource conservation, disaster prevention, boosting the development of the ecological industry, and improving the living environment for humanity.

Therefore, blue carbon pools are widely considered among the most precious ecological resources as they provide multiple benefits－helping improve the global governance system, ensuring ecological integrity amid climate actions, protecting biodiversity, and promoting sustainable development of the ocean.

China has been actively participating in the global blue carbon agenda and taking solid measures to promote scientific research and breakthroughs in natural science. China has included "blue carbon pools" into its climate change action plan and policy planning system for economic and social development, with a range of important deployments such as increasing the ocean carbon sinks, exploring pilot schemes for ecosystem carbon sinks, and exploring the construction of the standards and trading mechanism of blue carbon pools.

In the meantime, China has carried out many special action programs including the Blue Bay Remediation Project for bay restoration, integrated management and ecological restoration of the Bohai Sea, the national wetland conservation and restoration project which encourages the plantation of mangroves in the south and Chinese tamarisk in the north, and a mangrove conservation and restoration campaign.

In practice, such endeavors have been impeded by a series of challenges such as unclear property rights to natural resources, conflicts with people's livelihoods, overdevelopment and inadequate investment. China should formulate, as soon as possible, top-level design and development strategies for the construction of a blue carbon trading market to promote the capitalization of blue carbon resources. Consequently, it's necessary to carry out discussions at all levels on value calculation, confirmation of property rights ownership, people-land relationships, financing channels, and the economic and social benefits of the blue carbon ecosystems.

It is also imperative to develop some proper financial and supervision instruments, make innovations in financing (through insurance, debt swaps, taxation and credit), and encourage public-private partnerships, so as to motivate more concrete actions in pursuit of more notable benefits.

We firmly believe that China's ambition in tackling climate change, its contribution to global economic growth and environmental governance, green recovery in the post-pandemic era, and its leading role in the Belt and Road Initiative will provide strong support to the "China Blue Carbon Plan"－which promotes coordinated land and marine development, emissions reduction and carbon sinks enhancement, and sustainable economic and social development in coastal areas－and create a solid foundation for international cooperation in this regard.

Yang Yue is a post doctorate at the Center for Industrial Development and Environmental Governance at Tsinghua University. Chen Ling is director of the Center for Industrial Development and Environmental Governance at Tsinghua University. The authors contributed this article to China Watch, a think tank powered by China Daily. The views do not necessarily reflect those of China Daily.

中文译文

除了海洋可再生能源、海运交通、海底碳封存等减排场景，以海洋碳库为基础的减缓行动为限制全球变暖和实现温控目标提供了巨大动能。尽管这些行动在科学认知、技术方法、制度体系等方面仍存一系列的挑战，但可以预见的是，在双碳背景下，挖掘海洋碳库的固碳增汇潜力势必将成为基于自然的负排放体系建设以及气候金融资本追逐的下一个“风口”.

作为地球生态系统中最大的碳库，海洋是维持全球碳收支平衡及物质能量循环的关键，固碳增汇能力和效率远高于其他生态系统，相较于陆地生态系统参与碳循环形成的“绿色碳库”，海洋碳库又被形象地称作“蓝色碳库” (Blue carbon pool)。

双碳背景下，基于海洋碳库的解决方案的底层逻辑应该遵循两条基本路径:一是增加海洋“汇”的能力，二是降低海洋“源”的风险。对于前者，一个思路是通过向既定海域添加矿物，促进海洋生产力;第二个思路是充分利用海洋生态系统内部调节功能，通过改变不同海水层营养盐、无机碳、溶解氧供需错位问题，延长海洋碳循环的生命周期，提高海洋碳库自身的生产力。如我国科学家提出的人工上升流解决措施已被纳入IPCC发布的《气候变化中的海洋与冰冻圈特别报告》中。

全球约60%的海洋生态系统遭到破坏或正在退化，使得其碳汇能力持续衰退，甚至开始出现向碳源转化的风险，这给全球气候治理带来难以预估的挑战。因此，相较于“增汇”的思路，降低海洋“源” 风险的行动基本上围绕如何降低和修复人类活动对海洋生态环境的破坏展开。一是减少陆地施肥及营养盐入海，阻止近海水体富营养化导致的呼吸作用加剧，防止营养盐刺激海洋微生物降解更多有机质。二是保护和修复蓝碳生态系统，包括土壤和相关生物的恢复。

蓝碳生态系统的保护和修复除了增加海洋碳库的固碳增汇能力外，还能够提供资源养护、灾害防范、发展生态产业以及改善人居环境等重要生态服务价值。因而以蓝碳被认为是有助于完善国际气候治理体系，保证气候行动的生态完整性，实现生物多样性保护和海洋可持续发展等多重效益联动，最值得挖掘的生态资源之一。

目前，我国正积极参与国际蓝碳议程，扎实推进自然科学领域的科研攻关，将蓝碳纳入应对气候变化及经济社会发展政策规划体系，做出了包括“增加海洋碳汇”、“探索开展海洋等生态系统碳汇试点”和“探索建立蓝碳标准体系和交易机制”等一系列重要部署，并在国内开展“蓝色海湾”整治、渤海综合治理生态修复、“南红北柳”湿地保护恢复、红树林保护修复等专项行动计划。在实践的过程中，也遭遇了包括资源产权、生计冲突、过度开发和投资不足等一系列制约因素和现实瓶颈。需要尽早形成我国蓝碳市场建设的战略决策和总体思路，推进蓝碳资源资本化进程。因而，有必要在社会科学领域针对蓝碳生态系统价值核算、产权确权、人地关系、融资渠道、经济社会效益等多个层面深入探讨，并尝试通过开发适当的金融和监管工具、创新融资方式(保险、债务互换、税收和信贷)和可持续经营等公私伙伴关系，激发更为切实有效的行动积极性，并取得更为显著的综合效益。

相信有关全球气候变化应对的中国雄心、全球经济发展与环境治理的中国贡献、疫情后的绿色复苏以及“一带一路”倡议的中国引领，都将为实现包含海陆统筹、减排增汇、沿海经济和社会可持续发展的“中国蓝碳计划”提供了强劲的国力支持和国际合作基础。