The report, titled ‘Long-term Effectiveness and Consequences of Carbon Dioxide Sequestration’, assesses a number of sequestration/leakage scenarios – some of which have long been discarded by science and governments alike, such as CO₂ storage in the deep ocean.  

It confirms, unsurprisingly, that only geological storage would be effective in delaying the return of CO₂ to the atmosphere. Indeed a relevant IPCC report confirms that ‘well selected geological formations are likely to retain over 99% of their storage over a period of a thousand years’. 

The report confirms that leakage of stored CO₂ could cause negative effects such as ‘atmosphere warming, large sea level rise and oxygen depletion, acidification and elevated CO₂ concentrations in the ocean’. To counter potential leakage from CO₂ reservoirs re-storage could be examined, but it would be hard to measure CO₂ leakage rates so as to match it with re-storage.

The report emphasises the adverse effects that poor selection of CO₂ storage sites and inadequate monitoring could bring about for current and future generations. Adopted EU requirements on financial security and on liability of storage site operators in case of leakage should effectively prevent this from happening.