According to a research of Oxford University trees are the most efficient and cheapest way to sequester CO2 from the atmosphere, much cheaper and efficient than Geoengineering technology. See below the url-link to the report: http://www.smithschool.ox.ac.uk/research-programmes/stranded-asset/Stranded%20Carbon%20Assets%20and%20NETs%20-%2006.02.15.pdf