Ocean fertilization
Ocean fertilization or ocean nourishment refers to both natural and intentional processes that replenish iron and other nutrients in the upper ocean, which in turn stimulate the growth of phytoplankton and in some circumstances draw down large amounts of carbon dioxide (CO2) through photosynthesis. Intentional ocean fertilization is biomimicry of natural processes that have removed atmospheric CO2 before ice ages as well as after volcanic eruptions, whale defecation, and near hydrothermal vents.