Carbon Capture and Sequestration: Potential Environmental Impacts

Over the last few years, understanding of the profound implications of anthropogenically driven climate change has grown. In turn, this has fuelled research into options to mitigate likely impacts. Approaches involving the capture of carbon dioxide and its storage in geological formations, or in marine waters, have generated a raft of proposed solutions. The scale of some of these proposals is such that they will exert impacts of global significance in their own right. Proposals fall into two broad categories: • storage of liquid CO2 or products of reacted CO2 into intermediate/deep oceanic waters. • storage of liquid CO2 into sub-seabed or terrestrial geological formations. For the most part, while the technical feasibility of these schemata has been widely explored, the same is not true of their ecological implications. In the case of deep/intermediate oceanic waters, poor baseline understanding of the associated ecosystems is a considerable impediment to any reliable predictive assessment of likely impacts of carbon dioxide storage in these systems. Disruption of marine microbiological processes and degradation of benthic ecosystems, including those with high levels of endemicity, have been identified as potentially serious impacts. Similarly, the physiology, ecology and likely responses of micro-organisms present in targeted geological formations require evaluation prior to any consideration of the use of such formations for storage of CO2. In addition, the impacts of any leakage to surface need also to be considered. Accordingly this paper explores current uncertainties and detailed informational needs related to ocean and geological storage of fossil fuel-derived CO2. Particular emphasis is placed upon the ecological impacts of these proposals in relation to existing and emergent understanding of deep water/soil ecosystems and the indeterminacies attached to this understanding.