Carbon factors and models for forest carbon estimates for the 2005-2011 National Greenhouse Gas Inventories of the United States

Most nations have ratified the United Nations Framework Convention on Climate Change, and are mandated to report National Greenhouse Gas Inventories, including the land use, land use change and forestry sector when it is significant. Participating countries commonly use data from national forest inventories as a basis for their forest-related emissions estimates. The estimates are required to be consistent, comparable among parties, transparent, and well-documented. To help meet these requirements, we describe the data and methods used to calculate the forest carbon component of the United States' greenhouse gas emissions and sinks which we provided to the US Environmental Protection Agency to be compiled for the submission years 2005-2011. Past forest inventories were not designed to measure or take samples of data directly related to quantifying ecosystem carbon stocks necessary for greenhouse gas reporting. This study provides information used to bridge that gap and enable harmonized reporting. Specifically, we provide the forest inventory plot-data-to-carbon-stock conversion factors and associated uncertainty bounds in use for the reporting years prior to the availability of more directly measured or sampled carbon stocks. The factors are similar to default values supplied by the Intergovernmental Panel on Climate Change and current scientific literature. Overall, this approach indicates that forest ecosystems of the United States sequester approximately 170 Tg of carbon per year, which represents a net annual increase of half a percent of forest carbon stocks.