1. The floor

Soils are much more than building land, arable land or pasture, as they are home to countless plant and animal species and form the essential basis for human life. Soils contain around three times as much carbon in the form of organic matter as the atmosphere contains in the form of CO ₂ . Variations in soil organic carbon stock play a role in atmospheric CO ₂ concentration on time steps ranging from decades to centuries. Soils can thus contribute significantly, both positively and negatively, to changes in atmospheric CO ₂ content, and hence to climate change.

Soil is a complex living system, at the interface and in constant interaction with other environments. It can be...