Ocean Acidification

The capture and injection of carbon dioxide (CO2) into the deep ocean could provide a relatively long-term mitigation of climate change, but would come at the expense of enhancing acidification at the seafloor. We employ an Earth system model to survey the regional differences in the effectiveness and side effects of CO2 injection. Sequestration efficiency, as calculated relative to the ‘natural’ invasion from the atmosphere that would occur in the absence of mitigation, is highest for injection in the deep NW Pacific, but can be negative for shallow sites. For higher climate sensitivities and greater total emissions, sequestration efficiency is enhanced, decreasing the relative cost and increasing its potential value as a form of mitigation. However, CO2 injection increases the total area of seafloor bathed in under-saturated waters, with Atlantic sites inducing particularly large increases in seafloor undersaturation as well as having less favorable sequestration efficiency.

Ridgwell A., Rodengen T. J., & Kohfeld K. E., in press. Geographical variations in the effectiveness and side effects of deep ocean carbon sequestration. Geophysical Research Letters doi:10.1029/2011GL048423. Article (subscription required).