Water deep below ground has safely trapped carbon dioxide for millions of years and may one day help absorb emissions of the greenhouse gas to help slow climate change, researchers said yesterday.

The finding shows that such carbon capture and storage is possible provided scientists find an area where the geology is suitable, said Chris Ballentine, a researcher at the University of Manchester in the United Kingdom, who worked on the study.

This means locating ancient water systems thousands of meters below the surface to ensure gas doesn't escape back into the atmosphere.

"Clearly we want to bury carbon dioxide in the ground, that is a no-brainer," Ballentine said. "The big question is when we put carbon dioxide into the ground, how safe is it?"

The world is looking to limit emissions of greenhouse gases such as CO2 as climate scientists warn that their elevated global levels will lead to higher temperature, rising sea, drought and flood.

Capturing emissions from fossil fuel-burning power stations and burying them underground is a process that could keep up to a third of all carbon emissions out of the atmosphere, scientists say.

(Shanghai Daily via Agencies April 2, 2009)