One of the currently most popular research topics is Carbon Capture and Storage (technology to remove carbon dioxide directly from the atmosphere and storage it for long term). Most reviews on the topic (eg, Annual Review of Environment and Resources 2004, Technology Review 2007, Proceedings of the Combustion Institute 2007,
The Economist 2009) fail to include among these techniques the oldest and so far most efficient means to do so. I happened to be in front of one such device; it is about 60 cm tall, shining green and hardly moves. It is a plant!. Carbon dioxide gas is naturally removed from the atmosphere and converted into solid biomass matter by plants during photosynthesis.
In order to avoid the later release of this carbon when the plant dies or is destroyed, biochar technology could be used. Biochar (stable, solid and rich-in-carbon-content char created by pyrolysis of biomass) helps to lock carbon in the solid state for long periods of time. Done right, experts say, biochar produced and used appropriately, could contribute to the removal of carbon in combination with the millennia old technology of plant photosynthesis.