The ocean represents the largest potential sink for anthropogenic CO2. Discharging CO2 directly to the ocean would accelerate the ongoing, but slow, natural processes by which over 90% of present-day emissions are currently entering the ocean indirectly and would reduce both peak atmospheric CO2 concentrations and their rate of increase. This paper discusses the options for finding ocean sequestration strategies that are environmentally sound, economically viable, and technically feasible. In addition, some current research projects in this area are highlighted.
The ocean represents the largest potential sink for anthropogenic CO2. It already contains an estimated 40,000 GtC (billion tonnes of carbon) compared with only 750 GtC in the atmosphere and 2,200 GtC in the terrestrial biosphere (IPCC, 1996). As a result, the amount of carbon that would cause a doubling of the atmospheric concentration would change the ocean concentration by less than 2%.
Worldwide anthropogenic emissions of carbon to the atmosphere are about 7 GtC. The ocean-atmosphere flux is about 90 GtC per year, with a net ocean uptake of 2 ± 0.8 GtC (IPCC, 1996). On a time-scale of a thousand years, over 90% of today’s anthropogenic emissions of CO2 will be transferred to the ocean. Discharging CO2 directly to the ocean would accelerate this ongoing, but slow, natural process and would reduce both peak atmospheric CO2 concentrations and their rate of increase.