Large-scale seaweed cultivation as a nature solution for carbon-negative economy and restorative environmental stewardship: Lessons from China

The health of the world's oceans is intrinsically linked to the global climate and the well-being of humanity, which are under severe threats from human activities. Comprehensive strategies are urgently needed to protect marine environments and reduce greenhouse gas emissions to achieve the United Nations' Sustainable Development Goals. China is the largest seaweed producer, with an impressive share of over 50 % of the production of the global seaweed cultivation. This study traces the history of seaweed cultivation and illustrates the cases of important seaweed cultivation throughout China. Their profound contributions to ecological and economic benefits, as well as pivotal roles in advancing blue carbon and driving sustainable development, are unveiled. Seaweed cultivation in China has led to a significant reduction in CO2 emission by 35.49–72.93 Tg from 2003 to 2021, through the sequestration of recalcitrant dissolved organic carbon and the accumulation of sedimentary organic carbon, accounting for 17.43–35.72 % of the initially photosynthetically fixed carbon by seaweeds. As an innovative sustainable development model for a green and low-carbon economy, the theory of seaweed-based sustainable mariculture is proposed. Seaweed culture in China is a potential nature-based solution to tackle the marine environmental problems on a global scale. Seaweed cultivation mitigates global climate change, enhances carbon sequestration, reduces ocean acidification and hypoxia, as well as helps control eutrophication and harmful algal blooms. Therefore, it is proposed that large-scale seaweed cultivation be promoted in coastal countries for a sustainable future and that a paradigm be provided to establish the seaweed-based blue carbon economy worldwide.