Inclusion of Coastal Wetlands within the Inventory of United States Greenhouse Gas Emissions and Sinks

The Inventory of U.S. GHG Emissions and Sinks' (Inventory) chapter on Land Use, Land Use Change and Forestry (LULUCF) reports C stock changes and emissions of CH4 and N2O from forest management, and other land-use/land-use change activities. With the release of the 2013 Supplement to the 2006 IPCC Guidelines for National GHG Inventories: Wetlands (Wetlands Supplement) the United States has begun working to include emissions and removals from management activities on coastal wetlands, and is responding to a request by the United Nations Framework Convention on Climate Change (UNFCCC) for Parties to report back in March 2017 on their country's experience in applying the Wetlands Supplement. To support the EPA, NOAA has formed an interagency and science community group i.e., Coastal Wetland Carbon Working Group (CWCWG). The task of the CWCWG is to conduct an initial IPCC Tier 1-2 baseline assessment of GHG emissions and removals associated with coastal wetlands using the methodologies described in the recently released IPCC Wetlands Supplement for inclusion in the Inventory submitted to the UNFCCC in April 2017. The 5 million ha coastal land area of the conterminous United States has been delineated based upon tide stations and LIDAR derived digital elevation model. Land use change within the coastal land area has been calculated from NOAA Coastal Change Analysis Program (C-CAP), Forest Inventory and National Resource Inventory (NRI). Tier 2 (i.e., country-specific) subnational / climate zone estimates of carbon stocks (including soils), along with carbon sequestration rates and methane emissions rates have been developed from literature. Future opportunities to improve the coastal wetland estimates include: refined quantification of methane emissions from wetlands across the salinity gradient (including mapping of this gradient) and from impounded waters; quantification of impacts of forestry activities on wetland soils; emissions and removals on forested tidally influenced and palustrine wetlands on coastal land areas; the fate of carbon released from eroded wetlands; and the extent of seagrass along with the emissions and removals associated with anthropogenic impacts to them.