EPA Inventory of U.S. Greenhouse Gas Emissions

EPA Inventory of U.S. Greenhouse Gas Emissions
Name	EPA Inventory of U.S. Greenhouse Gas Emissions
Publisher	United States Environmental Protection Agency
First published	1990s
Latest release	Annual
Subject	Greenhouse gas emissions accounting
Country	United States

EPA Inventory of U.S. Greenhouse Gas Emissions is an annual quantitative accounting produced by the United States Environmental Protection Agency that compiles national estimates of anthropogenic emissions of major greenhouse gases. It informs United States Department of Energy, National Aeronautics and Space Administration, National Oceanic and Atmospheric Administration, United States Geological Survey, and United Nations Framework Convention on Climate Change reporting, and supports domestic policy making by agencies such as the Council on Environmental Quality, Department of Transportation, and Department of Agriculture. The Inventory integrates data used by stakeholders including Intergovernmental Panel on Climate Change, International Energy Agency, World Resources Institute, and subnational entities such as California Air Resources Board and New York State Department of Environmental Conservation.

Overview

The Inventory presents annual estimates of emissions and removals of carbon dioxide, methane, nitrous oxide, and fluorinated gases (including hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride) for the United States and its territories, aligning with methodologies from the Intergovernmental Panel on Climate Change and reporting obligations under the United Nations Framework Convention on Climate Change. It attributes emissions by sectors—energy, industrial processes, agriculture, land use, and waste—and provides time series that support analysis by institutions like the World Bank, Environmental Defense Fund, Natural Resources Defense Council, and academic centers such as Stanford University and Massachusetts Institute of Technology. The Inventory’s outputs feed into rulemaking at agencies like the Environmental Protection Agency itself, contributions to assessments by the National Academies of Sciences, Engineering, and Medicine, and inputs to multilateral fora including the G7 and G20.

Methodology and Data Sources

Methodologies draw on Intergovernmental Panel on Climate Change guidance, with emission factors and activity data sourced from federal datasets such as the U.S. Energy Information Administration, U.S. Department of Agriculture, U.S. Census Bureau, Bureau of Labor Statistics, and monitoring networks run by National Oceanic and Atmospheric Administration and National Aeronautics and Space Administration. The Inventory employs sector-specific approaches that reference technical protocols used by International Energy Agency, Food and Agriculture Organization, World Meteorological Organization, and standards from American Society for Testing and Materials. Data assimilation integrates facility-level reports from programs like the Greenhouse Gas Reporting Program and regulatory records from the Clean Air Act implementation, complemented by modeled estimates from research groups at Lawrence Berkeley National Laboratory and Oak Ridge National Laboratory.

Sectoral Emissions (by Source)

The Inventory breaks down emissions into major categories: energy production and use (including coal combustion, natural gas systems, and transportation fuels), industrial processes (including cement production, steelmaking, and chemical manufacture), agriculture (enteric fermentation, manure management, fertilizer use), land-use change and forestry (carbon sequestration in soils and biomass), and waste (landfills, wastewater). For example, energy sector data cross-references the U.S. Energy Information Administration fuel tables, while industrial process estimates use production statistics from the United States Geological Survey and trade data from the United States International Trade Commission. Agricultural emissions utilize activity data from the United States Department of Agriculture Census of Agriculture and research outputs from Iowa State University and University of California, Davis.

Trends and Historical Analysis

Time-series in the Inventory document long-term trends such as post-2000 declines in emission intensity associated with shifts from coal to natural gas and renewable energy deployment, periods of GDP-linked emission changes referenced by the Bureau of Economic Analysis, and episodic influences like economic recessions, extreme weather events tracked by National Weather Service, and policy-driven inflection points tied to initiatives from the Obama administration and Biden administration. Historical analysis compares Inventory results with independent top‑down estimates from satellite retrievals by NASA and inversion studies by research groups at Massachusetts Institute of Technology and Scripps Institution of Oceanography to identify sectoral drivers and attribution of emission changes.

Uncertainty, Quality Assurance, and Revisions

The Inventory includes quantified uncertainty ranges and QA/QC procedures aligned with Intergovernmental Panel on Climate Change recommendations, and documents iterative methodological revisions informed by reviews from the National Academies of Sciences, Engineering, and Medicine and technical consultations with International Energy Agency experts. Revisions respond to improved activity data from agencies such as the U.S. Energy Information Administration and updated emission factors from laboratories including Argonne National Laboratory and Pacific Northwest National Laboratory, and they are communicated through errata and methodological annexes used by analysts at Resources for the Future and Brookings Institution.

Policy Use and Reporting Requirements

Policymakers use Inventory outputs to design mitigation strategies under domestic statutes and executive guidance, support regulatory impact analyses for rules implemented under the Clean Air Act, and inform voluntary programs administered by Environmental Protection Agency offices and state agencies like the California Air Resources Board. The Inventory also supports statutory reporting obligations of federal agencies, budgetary planning by the Office of Management and Budget, and compliance frameworks relevant to state-level cap-and-trade programs such as Regional Greenhouse Gas Initiative.

International Comparisons and Reporting to the UNFCCC

For international reporting, the Inventory is formatted to meet United Nations Framework Convention on Climate Change biennial reporting guidelines and is compared with national submissions from parties including China, European Union, India, Japan, and Brazil. Comparative analyses are conducted by international organizations like the International Energy Agency and World Resources Institute, and cross-validated with global datasets from the Global Carbon Project and satellite-based observations from European Space Agency missions.

Category:Climate change in the United States