The ocean has played a crucial role in absorbing carbon dioxide emissions from human activities since the Industrial Revolution, but with the need to limit global warming becoming more urgent, there is increasing interest in enhancing the ocean’s carbon uptake capabilities. Climate simulations suggest that limiting warming by reducing emissions alone is becoming increasingly difficult, and active carbon removal from the atmosphere will be needed to mitigate the worst impacts of climate change. This is where the ocean’s immense capacity for storing carbon can be leveraged, as it can store about 19 times the amount of carbon that can be stored on land.
To meet the goals of the Paris Agreement, the world needs to significantly increase carbon removal efforts. While land-based methods of carbon removal, such as planting trees or restoring ecosystems, can contribute significantly, they alone may not be enough to achieve the necessary scale of carbon removal by 2050. This is where ocean-based carbon dioxide removal (CDR) strategies come into play, with the ocean’s vastness offering potential for large-scale carbon storage.
Various ocean-based CDR methods have been proposed, including seaweed farming, ocean iron fertilization, artificial upwelling and downwelling, enhanced rock weathering, electrochemical alkalinity enhancement, and direct ocean capture. These strategies involve innovative approaches to increase the ocean’s carbon uptake capabilities, but each comes with its own set of challenges and uncertainties. The lack of extensive research and baseline data on the environmental impacts of these methods poses a significant hurdle in implementing large-scale ocean CDR.
Research funding for ocean CDR projects has been increasing, with various initiatives being undertaken to explore the feasibility and effectiveness of these strategies. Seaweed farming, iron fertilization, rock weathering, and direct ocean capture have been tested in small-scale projects, but there is still much to learn about their long-term impacts and scalability. The urgency of the climate crisis requires that efforts to advance ocean CDR technologies are accelerated, while also addressing concerns related to environmental impacts and societal acceptance.
A combination of multiple CDR approaches may be necessary to achieve significant carbon removal targets, with each method complementing the strengths and weaknesses of the others. This integrated approach can help mitigate the challenges associated with individual methods and provide a more holistic and effective solution for ocean-based carbon removal. However, it is crucial to engage with communities and stakeholders throughout the research and implementation process to address concerns about the impacts of these technologies on local ecosystems and livelihoods.
Moving forward, responsible research and collaboration will be essential in developing a sustainable and effective ocean CDR agenda. As the urgency of addressing climate change grows, the ocean research community must work together to explore innovative solutions, engage with local communities, and navigate the complexities of implementing large-scale carbon removal projects. By balancing scientific advancements with societal considerations, the ocean has the potential to play a critical role in combating climate change and preserving the health of our planet for future generations.
