BIOLOGICAL IMPACT ASSESSMENT OF DIRECT CO2 INJECTION INTO THE OCEAN

Practical implementation of CO2 sequestration through direct injection of anthropogenic CO2 into the deep ocean could have a significant environmental impact on marine organisms. In this paper, we summarize recent advances in biological research for direct CO2 injection and discuss required research work for the future. Possible biological impacts caused by CO2 storage in the ocean can be categorized into acute and chronic. Acute impacts such as on the survival of marine organisms could be determined by laboratory and field experiments and assessed by simulation models. Chronic impacts, on the other hand, such as sub-lethal effects would be difficult to verify by the same approach as for acute impacts. One of the practical solutions for this issue is field experiments starting with controlled small-scale and, eventually, large-scale CO2 injection intended to determine ecosystem alteration. Practical implementation of CO2 ocean sequestration must employ a comprehensive monitoring program of its biological impacts. The ultimate criteria for the actual implementation of marine CO2 injection will be based on comparison of the biological responses of ecosystems affected by CO2 between the euphotic zone and the deep sea. Assessment is urgently needed of the comparative differences in marine-ecosystem alterations due to impacts to oceanic euphotic zones induced by the predicted increase in ambient CO2 levels in the atmosphere over the coming decades and impacts to the deep ocean through direct CO2 injection to sequester anthropogenic CO2