In order to gain regulatory and public acceptence of CO₂ storage it is necessary to understand how ecosystems associated with CO₂ storage sites might be affected should they be exposed to CO₂ leakage. There is a moderate level of knowledge as to how terrestrial systems might be affected through previous FP4 & 5 projects  and current studies on ecosystems around natural terrestrial CO₂ seeps (e.g. Carbo-Europe). However, the effect on shallow marine and subsurface ecosystems is virtually unknown. Since, in NW Europe, the greatest potential for CO₂ storage lies in rock strata lying beneath shelf seas, the sensitivities of shallow shelf marine ecosystems to potential CO₂ leakage is a vital component of  assessing risk and removing uncertainty.