Marine carbon dioxide removal may be a future climate solution

The ocean has absorbed 25% of anthropogenic CO₂ emissions and over 90% of excess heat, mitigating climate change but causing ocean acidification and marine ecosystem disruption. In addition to this natural role, various marine carbon dioxide removal (mCDR) techniques have been proposed, including biotic approaches such as blue carbon conservation and abiotic techniques such as ocean alkalinity enhancement. While biotic techniques are often preferred for their perceived ecological benefits, abiotic approaches offer higher sequestration potential and longer-term carbon storage. However, significant knowledge gaps and challenges remain, particularly in monitoring, reporting, and verification. As decarbonization progresses, mCDR could be essential for removing residual and legacy CO₂ emissions. Further research is needed to assess the effectiveness, impacts, and social acceptance of various mCDR techniques, ensuring the ocean's continued role in climate mitigation.