Abstract :
The eventual evasion of injected CO2 to the atmosphere is one consideration when assessing deep-sea disposal of CO2 as a potential response option to climate change concerns. Evasion estimated using an ocean carbon cycle model is compared to long-term trajectories for future CO2 emissions, including illustrative cases leading to stabilization of CO2 concentration at various levels. Modeled residence time for CO2 injected into the deep ocean exceeds the 100-year time-scale usually considered in scenarios for future emissions, and the potential impacts of climate change. Illustrative cases leading monotonically to constant CO2 concentration have been highlighted by the Intergovernmental Panel on Climate Change to give guidance on possible timing of emission reductions that may be required to stabilize greenhouse gas concentrations at various levels. For stabilization cases considered, significant modeled evasion does not occur until long after CO2 emissions have reached a maximum and begun to decline. Illustrative cases can also lead to a maximum in CO2 concentration followed by a decline to slowly decreasing concentrations. In such cases, future injection of emissions into the deep ocean leads to lower maximum CO2 concentration, with less effect on concentration later on in time.
