At present, global estimates suggest up to 25 billion tonnes of carbon dioxide are released into the atmosphere each year. One approach to mitigate rising carbon dioxide levels may be to capture and store carbon dioxide (referred to as carbon sequestration or carbon capture and storage (CCS)) rather than releasing it into the atmosphere. This is an emerging technology that is currently expensive and difficult to implement.
Carbon dioxide could be stored in underground geological formations including depleted oil and gas fields, deep aquifers, unminable coal seams and deep-sea sediments. There is also the potential for liquefied carbon dioxide to be stored in the deep sea, achieved by injecting liquefied carbon dioxide into great depths. Recently, Contracting Parties to the London Convention (1972 and 1996) adopted amendments on 2 November 2006 to Annex 1 of the 1996 Protocol to the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter, 1972 (London Convention) allowing the legal sequestration of carbon dioxide beneath the seabed (visit here). However, broad-scale CCS is not thought likely to occur for several decades.