America's Responsibility For Global Pollution: A Startling Percentage

The United States is the world's second-largest emitter of greenhouse gases, accounting for 11% of the global total. In 2022, the US emitted 6,343.2 million metric tons of CO2 equivalent, with the transportation sector being the largest contributor, accounting for 28.4% of emissions. The US has made commitments to reduce its emissions, with President Biden vowing to reduce emissions by 50-52% by 2030. While there has been some progress, with a 3% decrease in emissions since 1990, the country still faces challenges in addressing the climate crisis and reducing its carbon footprint.

Greenhouse gas emissions

The United States is the second-largest emitter of greenhouse gases, with emissions per capita higher than those of China, the largest annual emitter. In 2022, the US emitted 6,343.2 million metric tons of CO2 equivalent, a 0.2% increase from 2021 levels. This increase was driven by a rebound in economic activity after the COVID-19 pandemic, which caused a sharp decline in emissions in 2020. From 1990 to 2022, US greenhouse gas emissions decreased by 3%. During the same period, emissions per dollar of goods and services produced by the US economy (the gross domestic product or GDP) declined by 55%.

The transportation sector is the largest contributor to direct greenhouse gas emissions in the US, accounting for 28.4% of 2022 emissions. This is mainly due to the burning of fossil fuels for cars, trucks, ships, trains, and planes, with over 94% of the fuel used for transportation being petroleum-based. The electric power sector is the second-largest contributor, accounting for approximately 25% of emissions. In 2022, 60% of electricity in the US came from burning fossil fuels, mainly coal and natural gas.

Agriculture is another source of greenhouse gas emissions, with livestock, agricultural soils, and rice production contributing to emissions. Land use and forestry practices can act as a sink or a source of emissions. In the US, managed forests and other lands have acted as a net sink since 1990, absorbing more CO2 from the atmosphere than they emit and offsetting 13% of total gross greenhouse gas emissions.

The US Environmental Protection Agency (EPA) has implemented various programs and regulations to reduce greenhouse gas emissions, such as the Inventory of US Greenhouse Gas Emissions and Sinks and the Greenhouse Gas Reporting Program. However, in 2025, the EPA also announced a reconsideration of certain regulations, including the mandatory Greenhouse Gas Reporting Program, to reduce costs on the American energy supply.

Fossil fuel combustion

The transportation sector is the largest contributor to direct greenhouse gas emissions, with over 94% of the fuel used for transportation being petroleum-based, including gasoline and diesel. The electric power sector is the second-largest contributor, with 60% of electricity generated by burning fossil fuels, primarily coal and natural gas. The industrial sector is the third-largest contributor, with emissions from burning fossil fuels for energy and certain chemical reactions necessary for producing goods from raw materials. Commercial and residential emissions also contribute significantly, with fossil fuels burned for heat, refrigeration, and cooling in buildings.

In 2023, carbon dioxide emissions from fossil fuels continued to rise, reaching record levels. The burning of oil, coal, and natural gas impedes progress in limiting global warming. The concentration of carbon dioxide in the atmosphere has increased from approximately 278 parts per million in 1750 to 420 parts per million in 2023, contributing to rising global temperatures.

While the United States has made progress in reducing emissions of certain pollutants, such as lead compounds, and has seen a decrease in emissions per dollar of GDP produced, fossil fuel combustion remains a significant contributor to pollution. The United States must continue to address this issue to mitigate its impact on climate change and global warming.

Electric power

In 2022, the US electric power industry accounted for about 33% of total US energy-related CO2 emissions, while the electric power sector accounted for about 31%. The US electric power sector includes retail electricity sales to the residential, commercial, industrial, and transportation sectors.

The US electricity system is a complex network of power plants, transmission and distribution wires, and end-users of electricity. Most Americans receive their electricity from centralized power plants that use a wide variety of energy resources to produce electricity, such as coal, natural gas, nuclear energy, or renewable resources such as water, wind, or solar energy. This complex system of generation, delivery, and end-users is often referred to as the electric power grid.

In 2022, about 62% of total electricity generation in the US was produced from fossil fuels (coal, natural gas, petroleum, and other gases), materials that come from plants (biomass), and municipal and industrial wastes. Coal is the most widely used fuel in the United States, providing about 45% of electricity in 2010, followed by natural gas, which provided about 24%. Coal-fired power plants are responsible for a disproportionate amount of pollution. For example, in 2007, coal plants emitted about one-third of the nation's total global warming pollution.

To address the environmental impacts of the electric power industry, the US has implemented various measures and regulations. The Clean Air Act, administered by the US Environmental Protection Agency (EPA), regulates air pollutant emissions from most power plants and sets emissions standards. The Acid Rain Program, for instance, has helped substantially reduce emissions of major air pollutants. Additionally, the New Source Review (NSR) is a permitting process established in 1977 that requires the use of certain pollution control technologies for electricity-generating units.

To further reduce environmental impacts, new and existing power plants can increase generation efficiency, install pollution controls, and leverage cleaner energy supply resources. Distributed generation, such as renewable energy sources, can help deliver clean and reliable power while reducing electricity losses during transmission and distribution. Combined heat and power (CHP) is another approach that produces electricity and heat simultaneously from the same fuel source, improving energy efficiency.

Transportation

Cars and trucks are the most significant sources of transportation emissions, with passenger vehicles and commercial trucks accounting for 83% of CO2 emissions from the transportation sector in 2019. Road travel accounts for three-quarters of transport emissions, with passenger cars and buses contributing 45.1% and freight trucks contributing 29.4%.

The US Environmental Protection Agency (EPA) has been working to reduce transportation emissions through various programs and standards. The EPA's vehicle emissions standards have led to the development of cleaner and more efficient vehicles, with new passenger vehicles being 98-99% cleaner for most tailpipe pollutants compared to the 1960s. Fuels have also become much cleaner, with the elimination of lead and a 90% reduction in sulfur levels. The EPA's SmartWay light-duty program identifies the top-performing vehicles in terms of fuel economy and emissions to assist consumers in making environmentally friendly purchases.

In addition to the EPA's efforts, technological innovations offer viable options to reduce emissions from passenger vehicles. The rise of electric vehicles (EVs) is considered crucial for decarbonizing the transportation sector, as they have lower lifecycle emissions compared to internal combustion engines. While EVs only accounted for 10% of new light-duty vehicle sales worldwide in 2022, their adoption needs to accelerate to meet climate targets.

Other transport sectors, such as rail and freight, emit significantly less at only 1% of transport emissions. However, with the expected growth in transport demand worldwide due to increasing population and incomes, a comprehensive transformation of the transportation sector is necessary to achieve climate goals.

Agriculture

Agricultural pollution also has a substantial impact on water quality. The National Water Quality Assessment shows that agricultural runoff is the leading cause of water quality issues in rivers and streams, the third-largest source for lakes, and the second-largest source of impairments to wetlands. This runoff includes pesticides, fertilizers, and manure, which can contaminate water sources and harm aquatic ecosystems and drinking water supplies. Soil erosion and nutrient loss further exacerbate these issues.

The effects of agricultural pollution are far-reaching and detrimental. For example, high levels of manure and fertilizer from the Mississippi River regularly create a "'dead zone'" in the Gulf of Mexico, causing significant harm to marine life. Similarly, algal blooms fueled by nutrient runoff have devastated coastal communities in Florida, and eutrophication caused by phosphorus and nitrogen has led to the destructive overgrowth of algae.

However, it is important to note that there are opportunities to mitigate these issues. Adopting agroecology practices, such as crop rotation, increasing crop and animal diversity, and improving soil health, can help reduce pollution levels. These practices can also benefit farmers by reducing their reliance on chemicals and improving soil fertility and resilience to extreme weather events. By implementing these strategies and others, the agricultural sector can play a crucial role in reducing pollution levels and mitigating climate change.

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