Terrestrial Storage

Activities in forestry and agriculture can reduce and divert the atmospheric buildup of the three most important Greenhouse gases (GHGs) directly emitted by human actions: carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂0). Adoption of recommended management practices can enhance soil carbon and improve soil quality and productivity. Terrestrial sequestration is considered a near term approach to reducing GHGs because it can be implemented today. Moreover, soils provide a significant reservoir for organic carbon, storing twice as much as the atmosphere and three times as much as plants.

Soils
Many U.S. cropland soils have lost as much as 50% of their original organic carbon due to the effects of land clearing and tillage. It is estimated that U.S. cropland and grazing lands alone have the potential to store 150-380 million metric tons of carbon per year or 9.4-23.8% of total U.S. emissions. There are several land management practices that can increase soil organic carbon. Grazing lands, comprised of pasture and rangelands, represent the largest most diverse single land resource in the United States. As with croplands, the magnitude of the carbon input to the soil in grazing lands depends on several management approaches. Methods for increasing carbon storage include: residue management, improving the use of fertilizers, application of organic manure, planting improved species, regular use of prescribed burns to increase forage productivity, and improving grazing practices. Soils under grazing management have more soil organic carbon than those under cropping.

Forests
Forests cover about one-third of the United States, totaling about 750 million acres. The growth of forests and their management offers one of the most promising sources of carbon sequestration in the biosphere. The concept of offsetting carbon dioxide emissions by sequestering CO₂ in forests is not new. IPCC reviews concluded that globally, changes in forest management could induce future carbon sequestration adequate to offset an additional 15-20% of CO₂ emissions. Terrestrial carbon sequestration also provides the opportunity to trade carbon credits and reduce emissions voluntarily. Carbon sequestered by one party could offset emissions produced by another. The U.S. Department of Agriculture (USDA) and the U.S. Department of Energy (DOE) are currently developing accounting rules for sequestration projects and improving the voluntary GHG registry (1605b) and crediting system. Private sector groups such as the National Carbon Offset Coalition, the Chicago Climate Exchange, and Big Sky Partnership members, have initiated pilot market-based systems to trade CO₂.