GEOSEQUESTRATION (ge-o-se-que-stra-tion) n.: the storage of compresses near-liquid carbon dioxide in underground chambers.
Geosequestration is a seemingly sensible idea - trap polluting gases from power plants, compress them until they are liquid and pump them underground. No more greenhouse gases trapping heat in the atmosphere and, therefore, no global warming.
The nightmare scenario for geosequestration - also known as geostorage - occurred in Africa in 1986. In the dark of night, Lake Nyos in Cameroon emitted a huge cloud of carbon dioxide. The gas, which is heavier than air, settled in a thick layer over the surrounding area, asphyxiating 1800 people and countless animals.
The so-called "catastrophic release" is one reason why many groups are nervous about geostorage. But defenders of the process point out a couple of things. The Lake Nyos disaster was a natural disaster - the lake is in a volcanic basin where carbon dioxide occurs naturally on the lake floor. No sane power producer would pump carbon dioxide and other waste gases into a lake (ocean geostorage is possible but not popular). It would be pumped hundreds of metres underground into porous rock.