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Greenhouse Gases — An Overview

Scientific research suggests "greenhouses" that trap heat in the atmosphere are contributing to global warming. Some greenhouse gases, such as carbon dioxide, occur naturally and are emitted into the atmosphere both through natural processes and human activities.

The principal greenhouse gases that enter the atmosphere because of human activities are:

Carbon Dioxide (CO2): Carbon dioxide enters the atmosphere through the burning of fossil fuels (oil, natural gas and coal), solid waste, trees and wood products and as a result of other chemical reactions (such as the manufacture of cement).

Carbon dioxide also is removed from the atmosphere (or sequestered) when it is absorbed by plants as part of the biological carbon cycle. About 75 percent of all greenhouse gases emitted globally are CO2.

Methane (CH4): Methane is emitted during the production and transport of coal, natural gas and oil. Methane emissions also result from livestock and other agricultural practices and by the decay of organic waste in municipal solid waste landfills.

Nitrous Oxide (N2O): Nitrous oxide is emitted during agricultural and industrial activities, as well as during combustion of fossil fuels and solid waste.

Fluorinated gases: Hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride are synthetic, powerful greenhouse gases that are emitted from a variety of industrial processes. Fluorinated gases sometimes are used as substitutes for ozone-depleting substances (CFCs, HCFCs and halons).

These gases typically are emitted in smaller quantities, but because they are potent greenhouse gases, they sometimes are referred to as High Global Warming Potential gases (High GWE gases).

Americans make up less than five percent of the world’s population, yet they account for 25 percent of the carbon dioxide emissions. The U.S. ranks first or second, depending on whether it has been passed by China, in global greenhouse gas emissions.

Idaho is among the states with the lowest emissions of carbon dioxide (ranking 47th), however, the state emits more CO2 than roughly 100 nations.