Reported by Maheera Abdul Ghani, PhD student, University of Cambridge
Climate change is not only caused by the excess carbon dioxide in the atmosphere, but also the excess of carbon dioxide in the ocean system. The ocean has already absorbed about 30% of anthropogenic carbon dioxide, which causes an increase in acidity levels and poses a potential risk to marine ecosystems. Different carbon dioxide removal (CDR) strategies have been proposed by scientists that could be used in the ocean to enhance the natural processes through which the ocean absorbs and stores carbon dioxide from the atmosphere . However, the application of technologies for carbon dioxide removal from the ocean is not fully understood. How can ocean-based carbon dioxide removal technologies could be used in achieving net zero emissions in a sustainable way to solve the earth’s most pressing problem?
As part of the Cambridge Zero Climate Change Festival in October 2022, Dr. Si Chen (David MacKay Cambridge Zero Darwin College Research Associate) organised a critical discussion on ocean-based CDR and the development of a governance framework consistent with the Sustainable Development Goals (SDGs). The four expert panelists were: Andrew Hudson, former Head of UNDP Water and Ocean Governance Programme; Brian Von Herzen, Founder and Executive Director of the Climate Foundation; Kristian Teleki, Director of the Sustainable Ocean Initiative at World Resources Institute, Director of the Friends of Ocean Action for the World Economic Forum, and Head of the Secretariat of the High Level Panel for a Sustainable Ocean Economy; and Romany Webb, Associate Research Scholar at Columbia Law School and Senior Fellow at the Sabin Center for Climate Change Law. The event was chaired by Linda Jonsson, Associate Expert, UNEP Marine and International Waters Unit.
The panel discussed the application of technologies for carbon dioxide removal from the ocean and the essential need to map these technologies for the full range of SDGs. CDR from the atmosphere and storage on land or in the water are an important component of achieving net zero. The panel discussed various ocean CDR strategies such as seaweed cultivation. Panelists discussed the implications of ocean-based CDR technologies on SDGs such as food security. Along with the goal of net zero, it is important to focus on matters of food security. Millions of people depend on the ocean for their primary sustenance and improving food security is highly important for these communities. Regeneration of marine ecosystems is an essential goal for scalable nature-based ocean solutions that can ensure food security and enable large scale carbon export in the process. Processes such as ocean stratification have caused more than 60% of production losses, and due to heat waves, many seaweed farms were abandoned. Seaweed offshore cultivation through deep water irrigation provides an energy-efficient way of achieving sustainable food security. Seaweed forests can fix 15% more carbon dioxide than a tropical rainforest. These processes allow the use of vast areas of the ocean to enable productivity and regenerate marine habitats. In terms of SDGs, in developing countries where women are involved in the work field in coastal areas, these strategies can generate jobs for coastal communities and help achieve the SDG goal of reducing the gender gap.
There is a significant amount of uncertainty around the regulation of various CDR approaches, especially ocean-based methodologies. Activities involving the ocean are governed by a substantial framework of international law since they are considered a component of the global system. However, there isn't a complete international legal framework for ocean CDR at the moment. The panelists discussed the important factors for the development of new governance frameworks for ocean CDR. The existing international legal frameworks are patchworks of international agreements and lack proper governance frameworks for ocean-based CDR which is consistent with advancing the SDGs. For a responsible and informed development of CDR, a new approach towards risk assessment is necessary that accounts for both the risks associated with ocean CDR and the risks associated with unmitigated climate change. This will provide clarity on the balance between the potential for harm and the benefits of deployment. Moreover, the discussion highlighted the key factors hindering the development of ocean CDR. The challenges involved with measurements and verification of CDR tools are in need of a good knowledge base.
It is important to find a middle ground between the potential impacts of unabated climate change and the potential impacts of ocean CDR. Moreover, there is a need to define research and governance policies to protect the marine ecosystem. Cultivation and sinking of macroalgae as a climate change mitigation strategy might only be done on a very modest scale to avoid negative impacts on marine ecosystems and therefore be a very “niche” solution. It would require very close monitoring and oversight. The development of legal and legislative mechanisms is essential to enhancing the influence of ocean CDR development and the influence of these technologies on the SDGs.
 Filbee-Dexter K, Feehan CJ, Smale DA, Krumhansl KA, Augustine S, de Bettignies F, et al. (2022) Kelp carbon sink potential decreases with warming due to accelerating decomposition. PLoS Biol 20(8): e3001702.