Greenhouse gases trap heat in the Earth’s atmosphere affecting climate change. Some greenhouse gases such as carbon dioxide and water vapor occur naturally and are emitted to the atmosphere through natural processes and human activities. Other greenhouse gases are emitted mostly through human activities. The principal greenhouse gases caused by 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 also as a result of chemical reactions. Carbon dioxide is also removed from the atmosphere (or “sequestered”) when it is absorbed by plants as part of the biological carbon cycle.
Methane (CH4): Methane is emitted during the production and transportation of fossil fuels such as coal, natural gas, and oil. Methane emissions also result from raising livestock and agricultural practices, the decay of organic waste in solid waste landfills, and small amounts during the combustion of fossil fuels in transportation.
Nitrous Oxide (N2O): Nitrous oxide is emitted during agricultural activities such as soil management and animal manure management and industrial activities such as nitric acid and adipic acid production, as well as small amounts during combustion of fossil fuels and solid waste. N2O has a global warming potential that is 310 times higher than CO2.
Ozone Depleting Substances (ODS): Ozone depleting substances include refrigerants and foam blowing agents such as R-11, R-12, R-22 and R-114. ODS have historically been used in industrial applications such as air conditioning, refrigeration and foam blowing. These substances have very high global warming potentials, as much as 10,900 times that of CO2.