While greenhouse gases make up less than 0.1% of atmosphere they are what make the Earth inhabitable. The greenhouse effect is necessary for human life on Earth because without it the planet would not be warm enough. However, problems for humans, plants, and animals can arise when the greenhouse effect becomes stronger and the Earth becomes warmer than usual.
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It is carbon dioxide that is responsible for over 60% of this stronger greenhouse effect. Humans rely on the burning of coal, oil, and natural gas for energy. When these fossil fuels are burned carbon dioxide is released into the atmosphere. While this gas does occur naturally in the atmosphere it is not found in such high concentrations.
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One experience students may have to the greenhouse effect is the feeling of getting into a car on a hot summer day. The air inside the car feels much warmer than the air outside the car because it is trapped. While on Earth there are no physical boundaries in the atmosphere there are gases that actually hold the heat in. While greenhouse gases (discussed below) make up less than 0.1%.
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This carbon dioxide produced by humans then enters the natural carbon cycle. The carbon cycle involves the exchange of billions of tons of carbon each year between the atmosphere, oceans, soil, plants, and fossil fuels and cement production.
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Many billions of tons of carbon are exchanged naturally each year between the atmosphere, the oceans, and land plants. This exchange is known as the carbon cycle.
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The exchanges of this natural system are well balanced. Carbon dioxide levels appear to have varied little for the 10,000 years before 1800. In the last 200 years, however, levels of carbon dioxide in the atmosphere have increased well above those levels.
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Greenhouse Gases
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Water Vapor
Water vapor (H
2
O) is the most abundant and important greenhouse gas because it acts as a feedback to the climate. When the Earth’s atmosphere warms up the amount of water vapor also increases. The possibility of clouds and precipitation also increases, therefor creating an important feedback loop to the greenhouse effect.
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Carbon Dioxide
Carbon dioxide (CO
2
) is another important component in the atmosphere. This natural gas is released by natural process by humans though respiration and volcanoes during eruptions. Humans have also cause an increase in carbon dioxide by deforestation and the burning of fossil fuels. It has gained particular attention due to the increasing rate of carbon dioxide. Since the Industrial Revolution, CO
2
concentrations have increased by more than a third.
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Methane
Methane (CH
4
) is a hydrocarbon gas produced through natural sources as well as human activities such as, the decomposition of wastes in landfills, agriculture, and manure management. While methane is a more active greenhouse gas than carbon dioxide, it is found in much smaller amounts in the atmosphere.
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Nitrous Oxide
Nitrous oxide (NO
2
) is a powerful greenhouse gas created through the production of fertilizers and nitric acid and the burning of fossil fuels and biomass.
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Chlorofluorocarbons
Chlorofluorocarbons (CFCs) are synthetic materials. The production and release of these compounds into the atmosphere is now regulated through international agreements, as CFCs have contributed to the destruction of the ozone layer. After their ban, scientists have created ways replace their use in refrigerators.
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