The COMET tools are the official greenhouse gas quantification tools sanctioned by the USDA. COMET-Farm and COMET-Planner, and earlier versions of COMET, were developed through a partnership between NRCS, the USDA Climate Change Program Office (CCPO) and the Natural Resource Ecology Laboratory (NREL) Colorado State University. The tools are designed to support conservation scenario analysis and greenhouse gas inventories at the farm level for cropland, grazing lands, livestock, forestry, and agroforestry. COMET-Farm uses information on management practices on an operation together with spatially-explicit information on climate (PRISM weather model) and soil (NRCS SSURGO) conditions from USDA databases (which are provided automatically in the tool) to execute a combination of models to simulate sources of trace greenhouse gas emissions and potential carbon sequestration in soils and trees. By integrating NRCS SSURGO database and site-specific climate data, locality-specific results are presented to COMET-Farm users.