Sequestration of carbon dioxide is one of DOE's three basic carbon
management strategies for responding to global climate change.
Ocean sequestration is the purposeful enhancement of storage in the ocean of large amounts of carbon that would otherwise accumulate in the atmosphere and naturally enter the ocean over a longer time span. Careful scientific assessment of ocean carbon sequestration is needed to gain understanding of potential environmental consequences and engineering effectiveness of such manipulations.

Direct injection and fertilization are two different approaches to purposeful ocean carbon sequestration and there are multiple approaches for both. Fertilization is the purposeful enhancement of CO2 dissolution in the surface ocean from the atmosphere by adding critical micro-nutrients which stimulate carbon uptake by marine plants and the sedimentation of the photosynthetically fixed carbon to the deep sea. Direct injection requires the capture of CO2 from a point source, followed by injection of the CO2 at sufficient depths to ensure its retention.

Direct injection is more closely related to geological sequestration
because of the need to capture, compress, and transport carbon dioxide. Fertilization is more closely related to terrestrial sequestration because of the focus on enhancing biological conditions and the use of sunlight to drive the uptake of carbon dioxide from the atmosphere. However, the requisite scientific bases for future decisions regarding these approaches are closely linked through the global carbon cycle.