Environmental risks and performance assessment of carbon dioxide (CO₂) leakage in marine ecosystems

This chapter describes the state of the current understanding of the potential for CO ₂ leaked from carbon dioxide (CO₂) capture and storage (CCS) to impact the marine ecosystem. This is a complex problem as it requires an understanding of physical dispersion, the behaviour of plumes, marine chemistry, organism physiology and ecological relationships. Aside from predicting the likelihood of a leak event, the key issue is to understand the spread, persistence and impact of a hypothetical CCS derived leak and contrast this with, for example, trawling impacts and the global long-term consequences of climate change and the uptake of anthropogenically created atmospheric CO₂ (ocean acidification), which CCS seeks to mitigate. Excess CO ₂ in the marine system is undoubtedly harmful to many organisms. In the vicinity of a leak event, it is likely that significant ecological alteration would occur. Initial research indicates that only persistent leaks of a significant proportion of reservoir capacities would cause widespread and unacceptable impacts. However, much more research is required to determine critical leak magnitudes, within sediment interactions and ecosystem recovery before any comprehensive risk assessment of CCS can be delivered.