Evaluation of benefits of CO2 ocean sequestration

Abstract

The purpose of this chapter is to analyze the benefits of CO2 ocean sequestration for mitigation of global warming. “Benefit” here means reduced economic damage from global warming due to implementing sequestration. From the start of implementation of ocean sequestration, the rate of increase in the atmospheric concentration of CO2 is lowered compared to that if the technology is not adopted. This in turn begins to reduce the global mean temperature. This lowering of the rate of increase of atmospheric CO2 concentration and reducing of global mean temperature continue after completion of sequestration. This results in lowering of the peak values reached by both atmospheric CO2 concentration and the global mean temperature rise, mitigating economic damage induced by global warming. A novel method is proposed to calculate the benefit of CO2 ocean sequestration, which is expressed in dollars per ton of carbon sequestered. CO2 ocean sequestration is simulated by means of a simple atmosphere-ocean-land box model that accounts for the principal biogeochemical processes that control the global carbon cycle. Three scenarios are considered to reduce future atmospheric CO2 concentrations from business-as-usual forecasts to CO2 double stabilization. Atmospheric CO2 concentration and the increase in global mean temperature are simulated in cases with and without sequestration. The benefit is the difference between damage with and without sequestration. The result is that the benefit of CO2 ocean sequestration some hundreds of years in the future ranges from several hundreds to thousands of dollars per ton of carbon, well exceeding present-day estimated costs.