Organic Carbon in Soils of the World

The C stored in soils is nearly three times that in the aboveground biomass and approximately double that in the atmosphere. Reliable estimates have been difficult to obtain due to a lack of global data on kinds of soils and the amount of C in each soil. With new data bases, our study is able to provide more reliable data than previous estimates. Globally, 1576 Pg of C is stored in soils, with ≈ 506 Pg (32%) of this in soils of the tropics. It is also estimated that ≈ 40% of the C in soils of the tropics is in forest soils. Other studies have shown that deforestation can result in 20 to 50% loss of this stored C, largely through erosion.