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.

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.

More information about emissions from agriculture can be found in the agriculture chapter in the Inventory of U.S. Greenhouse Gas Emissions and Sinks.

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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.

Greenhouse gas emissions are often measured in carbon dioxide (CO2) equivalent. To convert emissions of a gas into CO2 equivalent, its emissions are multiplied by the gas's Global Warming Potential (GWP). The GWP takes into account the fact that many gases are more effective at warming Earth than CO2, per unit mass.

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

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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.

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).

The table shown below provides examples of opportunities to reduce emissions from homes and businesses. For a more comprehensive list of options and a detailed assessment of how each option affects different gases, see Chapter 9 and Chapter 12 of the Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change.

1. National Renewable Energy Laboratory (2023). NREL Researchers Reveal How Buildings Across United States Do—and Could—Use Energy. Shoemaker, Susannah

In 2022, direct and indirect greenhouse gas emissions from transportation accounted for 29% of total U.S. greenhouse gas emissions, making it the third largest contributor of U.S. greenhouse gas emissions when considering indirect emissions from distributed electricity. When considering only direct emissions, transportation is the largest contributor of U.S. greenhouse gas emissions (28%). From 1990 to 2022, total transportation emissions from fossil fuel combustion increased by 19%. From 2021 to 2022, emissions decreased by less than 1%. The largest sources of transportation greenhouse gas emissions in 2022 were light-duty trucks, which include sport utility vehicles, pickup trucks, and minivans (37%); medium- and heavy-duty trucks (23%); passenger cars (20%); commercial aircraft (7%); other aircraft (2%); pipelines (4%); ships and boats (3%); and rail (2%). In terms of the overall trend, from 1990 to 2022, total transportation emissions have increased due, in large part, to increased demand for travel. The number of vehicle miles traveled (VMT) by light-duty motor vehicles (passenger cars and light-duty trucks) increased by 47% from 1990 to 2022, as a result of a confluence of factors including population growth, economic growth, urban sprawl, and periods of low fuel prices. Between 1990 and 2004, average fuel economy among new vehicles sold annually declined, as sales of light-duty trucks increased. Starting in 2005, average new vehicle fuel economy began to increase, while light-duty VMT grew only modestly for much of the period. Average new vehicle fuel economy has improved almost every year since 2005, slowing the rate of increase of CO2 emissions.

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.

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The table shown below provides examples of opportunities to reduce emissions from agriculture. For a more comprehensive list of options and a detailed assessment of how each option affects different gases, see Chapter 7 of the Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change.

Emissions or sequestration of CO2, as well as emissions of CH4 and N2O, can occur from management of lands in their current use or as lands are converted to other land uses. Carbon dioxide is exchanged between the atmosphere and the plants and soils on land, for example, as cropland is converted into grassland, as lands are cultivated for crops, or as forests grow. In addition, using biological feedstocks (such as energy crops or wood) for purposes such as electricity generation, as inputs to processes that create liquid fuels, or as building materials can lead to emissions or sequestration.*

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

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When solid waste decomposes in landfills, it creates landfill gas, which is primarily comprised of CO2 and CH4. There are a number of well established, low-cost methods to reduce greenhouse gases from consumer waste, including recycling programs, waste reduction programs, and landfill methane capture programs.

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.

A million metric tons equals about 2.2 billion pounds, or 1 trillion grams. For comparison, a small car is likely to weigh a little more than 1 metric ton. Thus, a million metric tons are roughly the same mass as 1 million small cars.

Indirect emissions are produced by burning fossil fuel at a power plant to make electricity, which is then used by an industrial facility to power industrial buildings and machinery.

Greenhouse gases 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.

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Land Use, Land-Use Change, and Forestry in the United States is a net sink and offsets 13% of these greenhouse gas emissions. This net sink is not shown in the above diagrams. All emission estimates are sourced from the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990–2022.

In 2022, the net CO2 removed from the atmosphere from the LULUCF sector was 13% of total U.S. greenhouse gas emissions. Between 1990 and 2022, total carbon sequestration in the LULUCF sector decreased by 11%, primarily due to a decrease in the rate of net carbon accumulation in forests, as well as an increase in CO2 emissions from urbanization. Additionally, while episodic in nature, increased CO2, CH4 and N2O emissions from forest fires have also occurred over the time series.

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.

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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

* Emissions and sequestration of CO2 are presented under the Land Use, Land-Use Change, and Forestry sector in the Inventory. Other emissions from CH4, and N2O are also presented in the Energy sector.

In 2022, direct greenhouse gas emissions from the agriculture sector accounted for 9.4% of total U.S. greenhouse gas emissions. Greenhouse gas emissions from agriculture have increased by 8% since 1990. Agricultural soil management activities, such as application of synthetic and organic fertilizers, deposition of livestock manure, and growing nitrogen fixing plants, were the largest contributors to U.S. N2O emissions in 2022, accounting for 75% of total N2O emissions. Emissions from other agricultural sources have generally remained flat or changed by a relatively small amount since 1990.

In the LULUCF sector, opportunities exist to reduce greenhouse gas emissions and increase the potential to sequester carbon from the atmosphere by enhancing sinks. The table shown below provides some examples of opportunities for both reducing emissions and enhancing sinks. For a more comprehensive list, see Chapter 7 of the Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change.

Total emissions in 2022 are 6,343.2 Million Metric Tons of CO₂ equivalent. Percentages may not add up to 100% due to independent rounding. Greenhouse gas emissions from the commercial, residential, and industrial sectors increase substantially when indirect emissions from electricity end-use are included, due to the relatively large share of electricity use by buildings (e.g., heating, ventilation, and air conditioning; lighting; appliances and plug load) and use of electricity for powering industrial machinery. More information is also in the electricity end-use emissions section of this page.

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In the United States overall, Land Use, Land-Use Change, and Forestry (LULUCF) activities have resulted in more removal of CO2 from the atmosphere than emissions. Because of this, the LULUCF sector in the United States is considered a net sink, rather than a source, of CO2. In many areas of the world, the opposite is true, particularly in countries where large areas of forest land are cleared, often for conversion to agricultural purposes or for settlements. In these situations, the LULUCF sector can be a net source of greenhouse gas emissions.

The U.S. Inventory uses metric units for consistency and comparability with other countries. For reference, a metric ton is slightly more (approximately 10%) than a U.S. "short" ton.

The GWP values appearing in the Overview of Greenhouse Gases and Sources of Greenhouse Gas web pages reflect the values used in the U.S. Inventory, which are drawn from the IPCC's Fifth Assessment Report (AR5). For further discussion of GWPs and an estimate of greenhouse gas emissions using updated GWPs, see Annex 6 of the U.S. Inventory and the IPCC's discussion on GWPs (PDF) (106 pp, 7.7MB).

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.

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Plants absorb carbon dioxide (CO2) from the atmosphere as they grow, and they store some of this carbon as perennial aboveground and belowground biomass throughout their lifetime. Soils and dead organic matter/litter can also store some of the carbon from these plants depending on how the soil is managed and other environmental conditions (e.g., climate). This storage of carbon in plants, dead organic matter/litter and soils is called biological carbon sequestration. Because biological sequestration takes CO2 out of the atmosphere and stores it in these carbon pools, it is also called a carbon "sink."

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).

Electricity is used by other end-use sectors—in homes, businesses, and factories—and the greenhouse gas emissions from electricity generation can be allocated to the sectors that use the electricity. Looking at greenhouse gas emissions by end-use sector can help us understand energy demand across sectors and changes in energy use over time.

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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.

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

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.

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.

Note: Residential and commercial sector emissions presented here do not necessarily represent the full suite of emissions related to buildings and the broader built environment. The commercial and residential sectors numbers don’t include any emissions/sinks from production of construction materials (e.g., upstream emissions from production of cement, emissions and sinks from land use changes, etc.). Those would be reflected in other sectors. Also, as shown above, emissions from these sectors include other emissions that do not occur at the building site (i.e., landfills, etc.). Furthermore, energy use in these sectors may also include energy used for equipment (such as motor gasoline used for non-highway vehicles or lawn and garden equipment), exterior lighting, or construction. In addition, energy use for some large buildings, such as energy-intensive office buildings and factories with large onsite combustion, are typically included in industrial sector energy use.

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.