Greenhouse Gases

Did you know?

If there were no 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°F rather than the 57°F we currently experience.

Many of the chemical compounds in the earth’s atmosphere act as greenhouse gases. When sunlight strikes the earth’s surface, some of it radiates back toward space as infrared radiation (heat). Greenhouse gases absorb this infrared radiation and trap its heat in the atmosphere, creating a greenhouse effect that results in global warming and climate change.

Many gases exhibit these greenhouse properties. Some gases occur naturally and are also produced by human activities. Some, such as industrial gases, are exclusively human made.

What are the types of greenhouse gases?

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Source: Adapted from U.S. Environmental Protection Agency (public domain)

Several major greenhouse gases that are emitted as a result of human activity are included in U.S. and international estimates of greenhouse gas emissions:

• Carbon dioxide (CO2)
• Methane (CH4)
• Nitrous oxide (N2O)
• Industrial gases:
  • Hydrofluorocarbons (HFCs)
  • Perfluorocarbons (PFCs)
  • Sulfur hexafluoride (SF6
  • Nitrogen trifluoride (NF3

Other greenhouse gases that are not counted in U.S. or international greenhouse gas inventories

• Water vapor is the most abundant greenhouse gas, but most scientists believe that water vapor produced directly by human activity contributes very little to the amount of water vapor in the atmosphere. Therefore, the U.S. Energy Information Administration (EIA) does not estimate emissions of water vapor. Research by NASA suggests a stronger impact from the indirect human effects on water vapor concentrations.
• Ozone is technically a greenhouse gas because it has an effect on global temperature. At higher elevations in the atmosphere (the stratosphere), where ozone occurs naturally, ozone blocks ultraviolet (UV) light from reaching the earth’s surface, which is harmful to plant and animal life. Governments all around the world ban and control production and use of several industrial gases that destroy atmospheric ozone and create a hole in the ozone layer. At lower elevations of the atmosphere (the troposphere), ozone is harmful to human health. The United States has regulations to reduce the formation of this ground level ozone.