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The tropics cover 8.2 billion hectares or approximately 40% of the world's land area. These regions are characterized by a large portion of the world's rapidly increasing population, high risks of soil and environmental degradation because of harsh climate and resource-poor farmers, and rapid decomposition of soil organic matter because of continuously high temperatures. Predominant soils of the tropics include Oxisols, Aridisols, Ultisols, and Alfisols. Soil and ecosystem degradation lead to emissions of greenhouse gases (e.g., carbon dioxide, methane, and nitrous oxide) into the atmosphere. Anthropogenic activities that exacerbate gaseous emissions include deforestation and biomass burning, low- or no-input subsistence agriculture, plowing, drainage of wetlands, and elimination or shortening of restorative fallows. Soils of the tropics contain about 496 Pg of soil organic carbon (SOC) or 32% of the global pool. The historic loss of the SOC pool, due to land-use change and cultivation, may be 17-39 Pg compared with the global loss of 66-90 Pg. If 60-80% of the SOC lost can be resequestered through land-use change and adoption of recommended management practices, the potential of SOC sequestration in the tropics is 12-27 Pg over a 25-to 50-year period. Important strategies of SOC sequestration include reduction in emission of greenhouse gases and sequestration of carbon (C) in biomass and soils. The potential of C sequestration in soils and biomass of the tropics is estimated at 10.0-25.0 Pg by effective erosion control, 5.7-10.8 Pg through restoration of degraded soils and ecosystems, 58-115 Pg through biofuel offset, 2.2-4.1 Pg through adoption of recommended practices on croplands, and 6.0-12.0 Pg through adoption of recommended practices on grazing lands. Of this, the potential of SOC sequestration is only 13.9-26.9 Pg over the 50-year period. Realization of this vast potential is a challenge for researchers, land managers, and policymakers.