William Schlesinger, Box 90329, Duke Univ., Duke University, A246 LSC, Durham, NC 27708
Changes in the carbon stored in soils will have a dramatic impact on the levels of carbon dioxide in Earth's atmosphere and the rate of global warming during this century. Losses of organic carbon from soils at high latitudes may be balanced by increased storage of soil carbon from plant growth at high levels of atmospheric carbon dioxide. The results from Free-Air Carbon Dioxide Enrichment (FACE) experiments indicate only small net accumulations of soil carbon, largely in the forest floor. Thus, losses of carbon from boreal and peatland soils are likely to dominate the global change in the soil carbon pools. Changes of inorganic carbon in deserts will be much smaller, and not likely to impact the trajectory of atmospheric carbon dioxide. Most human efforts to increase soil carbon in agricultural soils produce short-term gains that are often not greater than the carbon dioxide released from the various actions taken to implement them.