11. Water Vapor (H2O) -
Water vapor, although it sounds innocent enough, is one of the biggest contributors to global climate change. Interestingly, water vapor is not directly emitted from human activity. It is in response to already rising temperatures. As the atmosphere becomes higher, the rate of water evaporation also increases. This water vapor tends to stay in the lower atmosphere where it absorbs infrared radiation and pushes it down to the earth’s surface, causing already hot temperatures to continue to rise.
10. Ozone (O3) -
Ozone presents itself in two forms, stratospheric and tropospheric. Stratospheric ozone occurs naturally. Tropospheric ozone, however, is a greenhouse gas that contributes to climate change. Humans produce this gas through industrial plants, chemical solvents, and burning fossil fuels. Prior to industrialization, tropospheric ozone was concentrated at 25 parts per billion in the atmosphere. Today, it is at approximately 34 parts. When O3 mixes with carbon monoxide, the combination results in smog. Taking public transportation, avoiding pesticides, and buying natural cleaning products are all ways to reduce ozone production.
9. Nitrogen Trifluoride (NF3) -
Nitrogen trifluoride is produced by industrial gas and chemical companies. It is recognized by the Kyoto Protocol as a greenhouse gas that contributes to global climate change. It has an atmospheric life of between 550 and 740 years. Under this environmental treaty, member countries have committed to reducing emissions of this gas.
8. Sulfur Hexafluoride (SF6) -
Sulfur hexafluoride is an electrical insulator, and generally is used in the form of a liquefied compressed gas. It is not very water soluble, but does dissolve in organic solvents. It has an atmospheric life of 3,200 years and global warming potential 23,900 times stronger than carbon dioxide. SF6 is considered one of the most dangerous greenhouse gases known. It is banned as a tracer gas and is limited to high voltage applications. In addition, the US Department of Energy repaired leaks in several laboratories, thereby reducing emissions by 35,000 pounds a year.
7. Hexafluoroethane (C2F6) -
Hexafluoroethane is a fluorocarbon that is used in the semiconductor industry, and is sourced from byproducts of aluminum production processes. It has a 10,000-year atmospheric lifespan and a global warming potential of 9,200. Prior to industrialization, this gas did not exist in the atmosphere. Humans may suffocate around this gas, if exposed to high concentrations.
6. Tetrafluoromethane (CF4) -
Tetrafluoromethane is a nonflammable gas that belongs to the fluorocarbon family. Utilization of the Hall-Heroult process in aluminum production results in this gas. Additionally, it is used as a refrigerant. CF4 is a strong greenhouse gas that contributes to climate change and has an atmospheric lifetime of 50,000 years. Because of its low concentration level in the atmosphere, it is not currently believed to have a significant radiative forcing effect, which leads to rising global temperatures. However, its presence is constantly increasing which will lead to global warming. It does not deplete the ozone.
5. Chlorodifluoromethane (CHClF2) -
Chlorodifluoromethane belongs to the hydrochlorofluorocarbon family of gases, and is most commonly used as a refrigerant and propellant. This greenhouse gas contributes significantly to ozone depletion and global warming. Despite the dangers associated with its use, CHCIF2 is sometimes used in place of other gases with higher ozone depleting potential. However, the European Union has banned manufacturing this gas as well as prohibited its use in servicing refrigeration and air conditioning equipment, and only recycled chlorodifluoromethane is permitted. Any broken equipment must be replaced by an alternative that does not contain this gas. The same reduction and phase-out strategy has been employed in the United States.
4. Dichlorodifluoromethane (CCl2F2) -
Most commonly referred to as Freon-12, Dichlorodifluoromethane is used in aerosol spray cans and as a refrigerant. It is believed to have an atmospheric life of approximately 102 years, when it is finally degraded by solar radiation. Unfortunately, its degradation actually allows it to destroy the ozone layer. A weak or broken ozone layer allows the sun’s ultraviolet rays to enter the earth’s atmosphere. It was a popular choice for auto air conditioning units prior to 1994. After the Montreal Protocol, manufacturing this greenhouse gas became illegal due to its disastrous effects on the ozone layer. It is, however, still permitted for use as a flame retardant in air vehicles and on submarines.
3. Nitrous oxide (N2O) -
Nitrous oxide is produced by industrial manufacturing, the combustion of fossil fuels, and the breakdown of agricultural fertilizer. Additionally, it occurs naturally in the ground. Nitrous oxide is a compressed liquefied gas that has an atmospheric life of 114 years and a global warming potential that is 298 times stronger than carbon dioxide. This means it traps heat in the earth’s atmosphere at a much higher rate than carbon dioxide. This gas has several uses, including as a rocket motor oxidizer, as an internal combustion engine speed booster, as an aerosol spray propellant, and as an anesthetic and pain reliever in dentistry, childbirth, and surgery around the world. The US government has agreed to analyze, measure, and publish greenhouse gas emission measurements per the United Nations Framework Convention on Climate Change. Of US emissions, approximately 75% come from the agricultural industry. Despite its danger to the environment, nitrous oxide is expected to remain one of the largest greenhouse gas emissions in the future.
2. Methane (CH4) -
Methane is 25 times stronger than carbon dioxide in terms of its global warming potential. It also has a lifespan of 12 years. This gas occurs both naturally and as a result of human activity. Naturally, it originates in wetlands, volcanoes, methane-producing insects and animals, and within the oceanic floor. Human activity such as burning fossil fuels, raising livestock, cultivating rice, and dumping in landfills are all contributing to increasing presence of this gas. When controlled, the earth has natural sinks that help absorb methane, however excess human production has proven to exceed what the earth can naturally absorb. Pre-industrial levels were approximately 700 parts per billion. Today, that has increased to 1,870 parts per billion.
1. Carbon Dioxide (CO2) -
Perhaps the most well-known global greenhouse gas is carbon dioxide. It occurs naturally in volcanoes, hot springs, groundwater, and glaciers. As these geologic formations release carbon dioxide, plants rely on it to perform photosynthesis which results in oxygen production. Today, human activity such as fossil fuel burning, cement production, deforestation, agriculture, and development all contribute to increased carbon dioxide production. It currently has 388,500 parts per billion in the atmosphere, which is an 108,500 increase since before industrialization. With such high concentrations in the atmosphere, plants are unable to keep up by removing it from the air. Because this gas absorbs and emits infrared radiation, it contributes significantly to global warming.
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