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Sources of Greenhouse Gases

Greenhouse gases contribute to global warming. They are gases that trap heat in the Earth's atmosphere, causing average temperatures to rise across the planet. A variety of energy and non-energy sources are responsible for greenhouse gas emissions, which the Environmental Protection Agency monitors annually. According to their 2011 inventory report, the total U.S. greenhouse gas emissions in 2009 were 6,639.7 teragrams of carbon dioxide equivalents, which is 6 percent less than the total for 2008.

  1. Livestock

    • Methane is one of the principle sources for greenhouse gases identified by the EPA. This gas is produced through various livestock-related activities, such as in enteric fermentation and manure management. Methane occurs as part of the digestive process in livestock. Part of the process involves livestock exhaling the methane as a byproduct due to the way in which materials break down in the stomach, which is known as enteric fermentation. Manure management, on the other hand, is the cultivation and management of manure, which is a large component of the agriculture industry. Methane is produced during the decomposition of the manure.

    Rice Cultivation

    • Rice cultivation activities breed the production of methane, classifying it as a human activity that emits greenhouse gases. When rice fields become flooded, organic matter decomposes in the soil, producing methane. The decomposition process is anaerobic, meaning "without oxygen." In flooded rice fields, oxygen levels are depleted, therefore serving as a prime environment for anaerobic decomposition. The condition of the soil determines how much methane is released in the process.

    Fossil Fuel Combustion

    • The combustion of fossil fuels is an activity that produces carbon dioxide, which is a major source of greenhouse gases. Gas, coal and oil used in automobiles, industrial plants and for generating electricity are the largest contributors to carbon dioxide emissions. The burning of fossil fuels is nearly entirely carbon dioxide, which goes directly into the atmosphere. In the United States, as of 2011 the largest source of fossil fuel combustion is electricity generation, at 41 percent of all carbon dioxide emissions. The utilization of fossil fuels, which are nonrenewable sources of energy, can be controlled to reduce the amount of carbon dioxide that is released and converted into greenhouse gases.

    Soil

    • Soil management activities produce nitrous oxide, a gas that contributes to the greenhouse effect. Soil contains a natural amount of nitrogen to start with, but certain activities to manage soil add more nitrogen, thereby increasing the amount of nitrous oxide that is emitted. The use of synthetic and organic fertilizers, for instance, elevates the natural levels of soil nitrogen, as well as the application of livestock manure to farmlands. Ground water that contains nitrogen also impacts the amount of nitrogen contained in soil. All of these factors contribute to the release of nitrous oxide, which is a source of greenhouse gases.

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