Many carbon dioxide removal (CDR) processes investigated to date are land-based. However, ocean-based approaches and processes are being increasingly explored. Because of its natural CO₂ uptake capacity, the ocean is the major player in the global carbon cycle. However, CO₂ uptake processes in the ocean and ocean floor occur on long time scales. Various CDR approaches could accelerate such processes and thereby increase the ocean’s CO₂ uptake rate. It is important to understand which methods are applicable at all, under which local and global conditions they work, and which approaches have to be discarded. In this context, science has the task of providing public and transparent information for informed and inclusive decision-making. Which solutions for countering climate change will be used in the future must be negotiated politically and in society in an open debate.
This briefing considers how ocean liming, one type of ocean alkalinity enhancement (OAE), could be realistically deployed as a method of CDR. OAE refers to interventions that increase the alkalinity of the upper ocean to increase uptake of atmospheric CO₂. There are currently multiple ongoing studies seeking to assess the CDR potential, and possible environmental risks, of different forms of OAE.
