What are greenhouse gases and how much are emitted by the United States?
Greenhouse gases trap heat from the sun and warm the planet's surface. Of U.S. greenhouse gas emissions, the majority are related to energy consumption, and most of those are carbon dioxide. From 1990 to 2011, energy-related carbon dioxide emissions in the United States increased by about 0.4% per year. The United States produced about 18% of the world's total energy-related carbon dioxide in 2010 — the last year for which comparable data are available.
Did You Know?
If it were not for naturally occurring greenhouse gases, the Earth would be too cold to support life as we know it. Without the greenhouse effect, the average temperature of the Earth would be about -2 degrees Fahrenheit rather than the +57 degrees Fahrenheit we currently experience.
Because greenhouse gases trap radiation (heat) from the sun and warm the planet's surface, a certain amount of these gases is beneficial (see "Did You Know?"). But as concentrations of these gases increase due to human activity, more warming occurs than would happen naturally. According to the U.S. Environmental Protection Agency, about 6.8 billion metric tons carbon dioxide equivalent (CO2e) of greenhouse gases were emitted by the United States in 2010 (the last year the full inventory is available).1 Other countries with significant emissions include China, the countries of Europe, Russia, and Japan.
What Specific Kinds of Greenhouse Gases Does the United States Emit?
The major greenhouse gases the United States emits as a result of human activity and that are included in U.S. and international emissions estimates are:
There are other greenhouse gases that are not counted in U.S. or international greenhouse gas inventories:
How Much of Total U.S. Greenhouse Gas Emissions Are Energy Related?
Of the total amount of U.S. greenhouse gases emitted in 2010, about 87% were energy-related and 91% of those energy-related gases were carbon dioxide from the combustion of fossil fuels.
Which Fuel Accounts for the Largest Share of Energy-Related Carbon Dioxide Emissions?
Petroleum is the largest fuel source of carbon dioxide emissions from energy consumption in the United States. Other important fossil fuel sources of carbon dioxide emissions include:
What Are the Important Non-Carbon Dioxide (Non-CO2) Greenhouse Gases Related to the Production and Consumption of Energy?
Of the non-CO2 gases that contribute to energy-related greenhouse gas emissions, methane contributes the most (6%) — mainly from emissions that leak out of natural gas systems, coal mines, and petroleum exploration and production facilities. Nitrous oxide contributes another 1% — from mobile and stationary combustion of fuels and waste.
How Are Energy-Related Carbon Dioxide Emissions Distributed Throughout Our Economy and What Sector of Our Economy Is Responsible for the Most Emissions?