Map Sources

[Gregory Monty]

Greenhousegases trap heat and make the planet warmer. Human activities are responsible for almost all of the increase in greenhouse gases in the atmosphere over the last 150 years.1 The largest source of greenhouse gas emissions from human activities in the United States is from burning fossil fuels for electricity, heat, and transportation.

EPA tracks total U.S. emissions by publishing the Inventory of U.S. Greenhouse Gas Emissions and Sinks. This annual report estimates the total national greenhouse gas emissions and removals associated with human activities across the United States by source, gas, and economic sector.

Since 1990, gross U.S. greenhouse gas emissions have decreased by just over 3%. From year to year, emissions can rise and fall due to changes in the economy, the price of fuel, and other factors. In 2022, U.S. greenhouse gas emissions increased 0.2% compared to 2021 levels. In 2020, there was a sharp decline in emissions largely due to the impacts of the coronavirus (COVID-19) pandemic on travel and other economic activity. In 2021 and 2022, the increase in total greenhouse gas emissions was driven largely by an increase in CO2 emissions from fossil fuel combustion due to the continued rebound in economic activity after the height of the COVID-19 pandemic. In 2022, CO2 emissions from fossil fuel combustion increased by 8% relative to 2020 and 1% relative to 2021. CO2 emissions from natural gas consumption increased by 5% relative to 2021. CO2 emissions from coal consumption decreased by 6% from 2021. The increase in natural gas consumption and emissions in 2022 is observed across all sectors except for U.S. Territories, while the coal decrease in primarily in the electric power sector. Emissions from petroleum use increased by less than 1% in 2022.

The Electricity power sector involves the generation, transmission, and distribution of electricity. Carbon dioxide (CO2) makes up the vast majority of greenhouse gas emissions from the sector, but smaller amounts of methane (CH4) and nitrous oxide (N2O) are also emitted. These gases are released during the combustion of fossil fuels, such as coal, oil, and natural gas, to produce electricity. Less than 1% of greenhouse gas emissions from the sector come from sulfur hexafluoride (SF6), an insulating chemical used in electricity transmission and distribution equipment.

Coal combustion is more carbon-intensive than burning natural gas or petroleum for electric power production. Although coal use accounted for 55% of CO2 emissions from the sector, it represented only 20% of the electricity generated in the United States in 2022. Natural gas use accounted for 39% of electricity generation in 2022, and petroleum use accounted for less than 1%. The remaining generation in 2022 came from non-fossil fuel sources, including nuclear (19%) and renewable energy sources (21%), which include hydroelectricity, biomass, wind, and solar.1 Most of these non-fossil sources, such as nuclear, hydroelectric, wind, and solar, are non-emitting.

In 2022, the electric power sector was the second largest source of U.S. greenhouse gas emissions, accounting for 25% of the U.S. total. Electric power sector emissions increased 7% in 2021. Greenhouse gas emissions from electric power production have decreased by about 15% since 1990 due to a shift in generation to lower- and non-emitting sources of electricity generation and an increase in end-use energy efficiency.

When emissions from electric power generation are allocated to the industrial end-use sector, industrial activities account for a much larger share of U.S. greenhouse gas emissions. Greenhouse gas emissions from commercial and residential buildings also increase substantially when emissions from electricity end-use are included, due to the relatively large share of electricity use mostly building related (e.g., heating, ventilation, and air conditioning; lighting; and appliances) in these sectors. The transportation sector currently has a relatively low percentage of electricity use and thus indirect emissions, but it is growing due to the use of electric and plug-in vehicles.

There are a variety of opportunities to reduce greenhouse gas emissions associated with electric power production, transmission, and distribution. The table below categorizes these opportunities and provides examples. For a more comprehensive list, see Chapter 6 (PDF) (88 pp, 3.6MB) of the Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change.2

The Transportation sector includes the movement of people and goods by cars, trucks, trains, ships, airplanes, and other vehicles. The majority of greenhouse gas emissions from transportation are carbon dioxide (CO2) emissions resulting from the combustion of petroleum-based products, like gasoline and diesel fuel, in internal combustion engines. The largest sources of transportation-related greenhouse gas emissions include passenger cars, medium- and heavy-duty trucks, and light-duty trucks, including sport utility vehicles, pickup trucks, and minivans. These sources account for over half of the emissions from the transportation sector. The remaining greenhouse gas emissions from the transportation sector come from other modes of transportation, including commercial aircraft, ships, boats, and trains, as well as pipelines and lubricants. Indirect emissions from electricity are less than 1 percent of direct emissions.

Relatively small amounts of methane (CH4) and nitrous oxide (N2O) are emitted during fuel combustion. In addition, hydrofluorocarbon (HFC) emissions also occur from the Transportation sector. These emissions result from the use of mobile air conditioners and refrigerated transport.

There are a variety of opportunities to reduce greenhouse gas emissions associated with transportation. The table shown below categorizes these opportunities and provides examples. For a more comprehensive list, see Chapter 10 of the Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change.1

The Industry sector produces the goods and raw materials we use every day. The greenhouse gases emitted during industrial production are split into two categories: direct emissions that are produced at the facility, and indirect emissions that occur off site but are associated with the facility's use of electricity.

Direct emissions are produced by burning fuel for power or heat, through chemical reactions, and from leaks from industrial processes or equipment. Most direct emissions come from the consumption of fossil fuels for energy. A smaller amount of direct emissions, roughly one third, come from leaks from natural gas and petroleum systems, the use of fuels in production (e.g., petroleum products used to make plastics), and chemical reactions during the production of chemicals, metals (e.g., iron and steel), and minerals (e.g., cement).

More information about facility-level emissions from large industrial sources is available through EPA's Greenhouse Gas Reporting Program data publication tool. National-level information about emissions from industry as a whole can be found in the sections on Fossil Fuel Combustion and the Industrial Processes chapter in the Inventory of U.S. Greenhouse Gas Emissions and Sinks.

In 2022, direct and indirect industrial greenhouse gas emissions accounted for 30% of total U.S. greenhouse gas emissions, making it the second largest contributor of greenhouse gas emissions of any sector. Direct greenhouse gas emissions from Industry account for 23% of total U.S. greenhouse gas emissions, making it the third largest contributor to direct U.S. greenhouse gas emissions, after the Transportation and Electric Power sectors. From 2021 to 2022, total energy use in the industrial sector decreased by less than 1%.Total U.S. greenhouse gas emissions from industry, including electricity, have declined by 22% since 1990.

There are a wide variety of industrial activities that cause greenhouse gas emissions, and many opportunities to reduce them. The table shown below provides some examples of opportunities for industry to reduce emissions. For a more comprehensive list, see Chapter 11 of the Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. 1

The Residential and Commercial sectors include all homes and commercial businesses (excluding agricultural and industrial activities). Greenhouse gas emissions from this sector come from direct emissions including fossil fuel combustion for heating and cooking needs, management of waste and wastewater, and leaks from refrigerants in homes and businesses, as well as indirect emissions from the use of electricity by homes and businesses (e.g., heating, ventilation, and air conditioning; lighting; and appliances, and plug loads). The building sector uses 75% of the electricity generated in the US.1

Indirect emissions are produced by burning fossil fuel at a power plant to make electricity, which is then used in residential and commercial activities, such as lighting and for appliances.

More national-level information about emissions from the residential and commercial sector can be found in the U.S. Inventory's Trends in Greenhouse Gas Emissions and Energy chapters (Chapters 2 and 4 respectively).

In 2022, direct and indirect greenhouse gas emissions from homes and businesses accounted for 31% of total U.S. greenhouse gas emissions. Direct emissions were 13% of total U.S. greenhouse gas emissions in 2022. Greenhouse gas emissions from homes and businesses vary from year to year, often correlated with annual fluctuations in energy use caused primarily by weather conditions. Total residential and commercial greenhouse gas emissions, including direct and indirect emissions, in 2022 have increased by less than 1% since 1990. Greenhouse gas emissions from on-site direct emissions in homes and businesses have increased by 8% since 1990. Additionally, indirect emissions from electricity use by homes and businesses increased from 1990 to 2007 but have decreased since then to approximately 4% below 1990 levels in 2021.

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