Wood as a carbon sink

In order to grow, a tree needs carbon dioxide from the air. The tree grows by photosynthesising water and carbon dioxide in the atmosphere using sunlight. The tree’s own ’building material’ comes from the carbon in carbon dioxide, at the same time releasing oxygen back into the atmosphere.

In order to grow, one kilogramme of wood needs about 1.55 kilogrammes of carbon dioxide from the air, the carbon of which is stored in the tree. About half of timber is carbon. A rule of thumb is that 1 cubic metre of wood stores 1 tonne of CO₂.

Photosynthesis is a biochemical process in which plant cells produces oxygen from CO₂ and water with the help of solar energy, and also glucose which the plant uses as nutrition. Six molecules of water (H₂O) and six of carbon dioxide (CO₂) form six oxygen molecules in addition to glucose.