Challenges and opportunities for marine carbon dioxide removal (mCDR)

Marine carbon dioxide removal (mCDR) refers to the techniques and technologies designed to increase the amount of carbon dioxide the ocean already captures and stores naturally through ecological and physical processes. As such, the deployment of mCDR could contribute to achieving global climate goals. However, many uncertainties and unknowns still surround these technologies, particularly concerning their efficiency and potential impact on ecosystems and societies. Moreover, the governance framework of mCDR is fragmented and falls short in adequately regulating the approaches undergoing development. To assess the status of current knowledge on mCDR, analyse governance challenges, and provide recommendations for mCDR research and potential deployments, we reviewed scientific literature and organised a series of workshops involving researchers and civil society representatives. Our recommendations are discussed and summarised into three key points: (1) the need to prioritise decarbonisation over mCDR deployment and limit the potential negative social and ecological impacts associated with these techniques; (2) the importance for research, based on clear guidelines, to play a crucial role in guiding mCDR development, and in particular on monitoring, reporting, and verification; (3) the urgency to strengthen and harmonise the governance framework of mCDR, which should be done in a way inclusive of civil society, ensuring equity and participation in all decision-making processes. We propose that these findings should guide both research agendas—including the seventh Intergovernmental Panel on Climate Change’s Assessment Report cycle (AR7)—and multilateral processes, in particular the London Convention and Protocol, the Convention on Biological Diversity, the United Nations Framework Convention on Climate Change, the United Nations Convention on the Law of the Sea, and the High Seas Treaty (BBNJ).