Exploring Marine CO² Removal as a Future Climate Solution

What is it about?

This perspective study highlights the critical role of the ocean in climate mitigation efforts. It first reiterates the ocean’s role in absorbing excess heat and a significant fraction of anthropogenic CO² emissions. It then discusses the potential of marine carbon dioxide removal (mCDR) techniques to further enhance this role, addressing the need for effective carbon removal strategies to mitigate residual and legacy CO² emissions. These techniques include both biotic methods, such as blue carbon conservation, and abiotic approaches, like ocean alkalinity enhancement (OAE), with a discussion on their potential effectiveness and environmental impacts. The study argues that while biotic techniques are often favored for their perceived ecological benefits, abiotic methods offer greater sequestration potential and longer-term carbon storage, mirroring the fact that the current ocean carbon sink is driven almost entirely by geochemical rather than biotic processes. The potential carbon removal capacity and storage duration of OAE are notably higher than those of other methods, suggesting a need to reconsider the current preference for biotic solutions. The text highlights the need for further research to address knowledge gaps, including those related to social acceptance, governance, environmental impacts, and monitoring, reporting, and verification of these techniques.

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Photo by Daiki Sato on Unsplash

Photo by Daiki Sato on Unsplash

Why is it important?

The study lays out the potential role of marine carbon dioxide removal in mitigating increases in atmospheric CO², and emphasizes the need for further research to assess the efficacy, impacts, and social acceptance of these techniques before we can know whether they could be effective climate solutions. Key Takeaways: 1. The perspective study highlights the ocean's significant natural capacity to absorb CO² and heat, which has mitigated climate change impacts but has also led to ocean acidification and marine ecosystem disruption. 2. The study discusses the potential of abiotic mCDR techniques, such as ocean alkalinity enhancement, for higher carbon removal potential and longer-term storage compared to biotic methods, despite their lower political and social acceptability. 3. It underscores the importance of addressing knowledge gaps and challenges in social acceptance, governance, environmental impacts, and monitoring and verification of mCDR techniques to ensure their effective contribution to climate mitigation and the continued viability of ocean ecosystems. 4. It emphasizes that we need rapid and massive reductions in greenhouse gas emissions and that no form of CDR is a climate solution while human activities are still emitting significant amount of CO² .