The U.S. Environmental Protection Agency’s (EPA) Greenhouse Gas Reporting Program (GHGRP) collects and disseminates annual greenhouse gas (GHG) data from individual facilities and suppliers across the U.S. economy. EPA also develops the annual Inventory of U.S. Greenhouse Gas Emissions and Sinks (Inventory) to track total national emissions of greenhouse gases to meet U.S. government commitments to the United Nations Framework Convention on Climate Change. The GHGRP and Inventory datasets are complementary and may inform each other over time. However, there are also important differences in the data and approach. These differences are highlighted here to help stakeholders understand these data sources and use them appropriately.

Key differences between GHGRP data and the U.S. GHG Inventory:

• Approach to collecting and reporting data. The U.S. GHG Inventory is largely developed with a “top down” approach using aggregated national data to develop emissions estimates for the entire U.S. economy. For many sources, the Inventory data cannot be broken down to show emissions by facility. The GHGRP uses a “bottom up” approach. It collects GHG data for every facility and supplier that is required to report, which allows the data to be grouped and categorized in a variety of useful ways including by facility, location, and industry group.

• The percentage of U.S. GHG emissions covered. The U.S. GHG Inventory provides a comprehensive picture of all GHG emissions and covers 100 percent of man-made emissions in the U.S. The 2010 GHGRP data covers roughly 80 percent of total U.S. GHG emissions. This is because the GHGRP only requires reporting from large direct emitters of GHGs from certain industries and suppliers of certain fossil fuels and industrial gases. Direct emitters in the GHGRP report roughly half of total U.S. emissions; additional GHG data is reported by the suppliers. The GHGRP does not include GHG emissions from certain diffuse sources such as agricultural soil management and enteric fermentation by livestock.

• Inclusion of forestry and land use. The Inventory tracks national greenhouse gas emissions associated with land use and land use change and sequestration of carbon dioxide in forests and other managed lands. As displayed in the 2014 Inventory, this sector absorbed a net 762 million metric tons of CO₂. The GHGRP data does not include data related to emissions or absorption of GHGs on forests and other lands.

• The timeframe of emissions data. The GHGRP began in 2010 and will collect data annually going forward. Facilities are not required to estimate emissions for years prior to 2010. The current U.S. GHG Inventory presents national estimates starting in 1990 and for each subsequent year through 2014. The next U.S. GHG Inventory, covering 2015 data, will be released for public review in February 2017 and finalized in April 2017.

• The procedures for calculating emissions. Both the U.S. GHG Inventory and the GHG Reporting Program use methodologies that are consistent with the internationally agreed upon procedures developed by the Intergovernmental Panel on Climate Change (IPCC). For the GHG Reporting Program, facilities collect detailed information specific to their operations (e.g., natural gas used by a plant) according to detailed measurement standards, whereas the data collected for the U.S. GHG Inventory are at a more aggregated level (e.g., natural gas used by the country).

• Definitions of sectors and industry groupings. The definitions of sectors and industry groupings in the Inventory and the GHGRP data are not always the same. Users should check the definitions of industry sectors in the two data sets before making comparisons.