Helena Joyce
The United States is one of the world's largest emitters of greenhouse gases, with emissions totalling 6,343 million metric tons of carbon dioxide equivalents in 2022. This figure has decreased by 3% since 1990, though emissions increased by 1% in 2022 compared to 2021. The largest sources of greenhouse gas emissions in the US are the burning of fossil fuels for electricity, heat, and transportation, as well as agricultural practices such as livestock production and the use of nitrogen fertilizer.
| Characteristics | Values |
|---|---|
| Greenhouse gas emissions in 2022 | 6,343 million metric tons (14 trillion pounds) of carbon dioxide equivalents |
| Percentage change in greenhouse gas emissions since 1990 | 3% decrease |
| Methane emissions change since 1990 | 19% decrease |
| Nitrous oxide emissions change since 1990 | 5% decrease |
| Fluorinated gases emissions change since 1990 | 58% increase |
| Largest contributing sector to emissions in 2022 | Transportation (28.4%) |
| Second-largest contributing sector to emissions in 2022 | Electric power/power plants (25%) |
| Percentage of US population breathing unhealthy levels of air pollution | 46% (about 156 million people) |
| US population growth from 1970 to 2023 | 63% increase |
| Total emissions of the six principal air pollutants change from 1970 to 2023 | 78% decrease |
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What You'll Learn
Greenhouse gas emissions from industry
In 2021, the United States emitted over 6.3 billion metric tons of greenhouse gases (CO2e). Carbon dioxide accounted for the largest percentage of greenhouse gases (79%), followed by methane (12%), nitrous oxide (6%), and other greenhouse gases (3%). The total US emissions for 2021 were 6,340 million metric tons of CO2e, and net emissions, taking sinks into account, totalled 5,586 million metric tons of CO2e. US greenhouse gas emissions in 2022 totalled 6,343 million metric tons (14 trillion pounds) of carbon dioxide equivalents, a 3% decrease since 1990.
The US military is responsible for a significant amount of greenhouse gas emissions. The Pentagon, including its installations and 700 bases, accounts for about 40% of US military emissions, while 60% are operational emissions from fuel use in war, training, and exercises. The US military industry, including companies manufacturing weapons and equipment, generates more than double the greenhouse gases emitted by the Pentagon annually.
The leading sources of greenhouse gas emissions in the US are the transportation and electric power sectors. Transportation accounted for 28.4% of 2022 emissions, and electric power accounted for approximately 25%. Methane emissions from top oil and gas producers have decreased by 19% due to reduced emissions from landfills, coal mines, and natural gas systems. Nitrous oxide emissions, mainly from agricultural soil management, decreased by 5%. However, emissions of fluorinated gases from commercial, industrial, and household uses increased by 58%.
The US Environmental Protection Agency (EPA) has taken steps to reduce greenhouse gas emissions, such as the Greenhouse Gas Reporting Program implemented during the Obama administration, which required large carbon polluters like refineries, power plants, and landfills to report emissions. This rule has contributed to a collective 20% drop in emissions from these sources. However, the Trump administration's EPA has targeted this and other environmental rules for repeal, arguing that they impose costly and burdensome requirements on industries.
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Fossil fuels for electricity, heat, and transport
Fossil fuels, including coal, oil, and natural gas, have been the primary energy source for the US economy for over 150 years. In 2023, fossil fuels accounted for about 84% of the country's primary energy production. The transportation sector, which relies heavily on petroleum, accounted for the largest share of energy consumption at 89%. The electric power sector, on the other hand, accounted for about 96% of total US energy consumption in 2023, with natural gas as the primary energy source.
While natural gas emits less carbon dioxide and air pollutants than coal when generating electricity, leaks from natural gas plants, wells, and pipelines release methane, a greenhouse gas 25 times more potent than carbon dioxide in trapping heat in the atmosphere. In 2020, natural gas was responsible for 36% of US greenhouse gas emissions. Oil, on the other hand, was the largest source of US energy-related carbon emissions in 2020, with combustion contributing to 45% of carbon dioxide emissions that year.
The US has made progress in transitioning to cleaner energy sources. In 2023, renewable energy production and consumption reached record highs, accounting for about 9% of total primary energy production and consumption. Nuclear energy also played a significant role, contributing about 9% of total US energy consumption.
However, the US still faces challenges in reducing its reliance on fossil fuels. The transportation sector, which accounts for the majority of oil consumption, continues to be the largest contributor to greenhouse gas emissions. In 2021, year-over-year transportation sector emissions grew by nearly 11%. Additionally, while the use of natural gas has helped reduce carbon emissions, it is not a sustainable long-term solution due to its methane emissions.
To summarize, the US has made strides in diversifying its energy sources, but fossil fuels continue to dominate, particularly in the transportation and electricity sectors. The transition to cleaner energy sources, such as renewables and nuclear energy, is crucial to reducing the country's pollution levels and mitigating the worst effects of climate change.
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Commercial and residential sector emissions
In 2022, the residential and commercial sectors accounted for 31% of total US greenhouse gas emissions, or 6,343 million metric tons of CO2 equivalent. This figure includes direct and indirect emissions. Direct emissions from commercial and residential sources made up 13% of total US greenhouse gas emissions in 2022.
Direct emissions are produced by residential and commercial activities in several ways. The combustion of natural gas and petroleum products for heating and cooking emits carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). In 2022, emissions from natural gas consumption represented 78% of direct fossil fuel CO2 emissions from the residential and commercial sectors. Coal consumption is a minor component of energy use in these sectors. Other sources of direct emissions include waste and wastewater management, and leaks from refrigerants in homes and businesses.
Indirect emissions are produced when fossil fuels are burned at power plants to generate electricity, which is then used in residential and commercial activities such as lighting and appliances. When indirect emissions from electricity end-use are included, commercial and residential sector emissions increase substantially. This is largely because buildings use 75% of the electricity generated in the US.
It is important to note that the residential and commercial sector emissions presented do not include emissions/sinks from the production of construction materials or emissions from land use changes. Those would be reflected in other sectors. Additionally, energy use in these sectors may also include energy used for equipment, exterior lighting, or construction.
From 1990 to 2022, US greenhouse gas emissions per dollar of goods and services produced by the US economy (GDP) declined by 55%. This decrease may be due to increased energy efficiency and structural changes in the economy. However, emissions can fluctuate from year to year due to various factors such as the economy, fuel prices, and weather conditions. For example, in 2024, residential sector emissions decreased due to lower natural gas and petroleum consumption, while commercial sector emissions remained relatively unchanged.
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Agriculture and livestock emissions
Agriculture contributes about 10% of total US greenhouse gas emissions, excluding emissions from onsite fossil fuel use. This includes emissions of carbon dioxide, nitrous oxide, and methane. These gases can be converted into "carbon dioxide equivalents" (CO2e) based on their impact on climate change.
Agricultural emissions are the result of complex natural processes that are challenging to measure, unlike emissions from burning fossil fuels. Methane, the most significant contributor to agricultural emissions, comes primarily from livestock digestion (known as enteric fermentation) and manure management. Cattle, in particular, contribute the most methane, and the growth in US methane emissions has been linked to the rising population of beef cattle. All livestock, not just ruminants, contribute to methane emissions from manure decomposition.
Nitrous oxide is the second-largest contributor to agricultural emissions, primarily resulting from fertilizer application to soils and manure management. Adopting strategies such as avoiding fertilizer application to very wet or cold soils, using legumes as cover crops, and employing manure management techniques that capture and utilize emissions can help curb nitrous oxide and methane emissions.
Carbon dioxide emissions in agriculture arise from increased decomposition of plant matter in soils and land conversion for agricultural use. These emissions are partially offset by the increased plant matter stored in cropland soils. Implementing cover cropping, utilizing cultivation methods that minimize soil disturbance, and increasing carbon dioxide storage in agricultural soils can contribute to reducing carbon dioxide emissions.
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Transportation sector emissions
The transportation sector is a significant contributor to US greenhouse gas emissions. In 2022, transportation accounted for the largest portion, 28-29% of total US greenhouse gas emissions. Cars, trucks, commercial aircraft, and railroads are all part of the transportation sector's emissions. It is important to note that transportation emissions do not include emissions from non-transportation mobile sources such as agricultural and construction equipment.
The majority of emissions in the transportation sector come from cars and trucks. Motor vehicles accounted for 83% of CO2 emissions from transportation in 2019. Personal vehicles and commercial trucks, being the most common modes of passenger and freight transportation, emit more CO2 per passenger-mile or ton-mile than other modes of transportation. Despite an increase in travel by car and truck, CO2 emissions have declined since 2005 due to improved vehicle efficiency. The average fuel economy of new light-duty vehicles rose from 20 miles per gallon in 2005 to 25 miles per gallon in 2021.
The transportation sector relies heavily on a single fossil fuel, petroleum, which has a higher price per unit of energy than other fossil fuels due to refining costs. However, there are currently few cost-effective alternatives. The price of embedded CO2 in the transportation sector is more than double that of other sectors. This makes reducing emissions from transportation more challenging than in sectors like electricity generation.
To address transportation sector emissions, the Congressional Budget Office projects a 9% decrease in CO2 emissions from 2021 to 2032. This is due to more stringent fuel economy standards and the growing popularity of electric vehicles. Tighter standards for fuel economy and emissions are expected to reduce emissions over the next decade. Additionally, the increasing use of electric vehicles is projected to contribute to greater emissions reductions in the future as the electric power sector becomes less carbon-intensive.
In summary, the transportation sector is a major contributor to US greenhouse gas emissions, with vehicles being the primary source of these emissions. However, improvements in fuel economy and the shift towards electric vehicles are expected to reduce emissions in the coming years.
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Frequently asked questions
America produces over 6 billion metric tons of pollution each year. In 2021, the United States emitted more than 6.3 billion metric tons of greenhouse gases. In 2022, U.S. greenhouse gas emissions totaled 6,343 million metric tons of carbon dioxide equivalents.
The largest source of pollution in the United States is the burning of fossil fuels for electricity, heat, and transportation. The transportation sector accounts for the largest share of emissions, at 28.4% in 2022. The electric power sector is the second-largest contributor, accounting for approximately 25% of emissions in 2022.
The commercial and residential sectors contribute significantly to America's annual pollution output. When indirect emissions from electricity end-use are included, these sectors account for a much larger share of U.S. greenhouse gas emissions. This is because buildings use 75% of the electricity generated in the U.S. for heating, ventilation, air conditioning, lighting, and appliances.
America's annual pollution levels have generally decreased over time, with some fluctuations. From 1990 to 2022, U.S. greenhouse gas emissions per dollar of goods and services produced by the economy (GDP) declined by 55%. Net emissions declined by 15% from 2005 to 2021. However, emissions increased by 1% in 2022 compared to 2021, driven by increased CO2 emissions from fossil fuel combustion.
