Phytoplankton need nutrients such as iron, nitrogen and phosphorus compounds in order to grow. However, there is a deficit of these nutrients in many ocean regions. Scientists have therefore developed the concept of ocean fertilization; this involves seeding the ocean’s surface with iron to encourage phytoplankton growth. In theory, more phytoplankton would remove more carbon dioxide from the atmosphere and convert it into carbohydrate, which would then sink into the deeper ocean. Thirteen research experiments conducted at sea confirm that increased nutrient input does indeed lead to more phytoplankton growth. However, the scientists have been unable to find firm evidence of increased carbohydrate transport into the deeper ocean. What’s more, there is still a lack of comprehensive data on the potential risks of ocean fertilization and its impacts on humans and nature.
For that reason, a regulatory mechanism was established to prohibit ocean fertilization for commercial purposes (e.g. sale of emissions allowances) in international waters, although it is still permitted for research. This regulatory mechanism is based on an amendment to the 1996 London Protocol, which updates and is intended to replace the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter (London Convention) in the long term. However, as only six countries have ratified the new version of the London Protocol thus far, it has not yet entered into force under international law.