Carbon dioxide and methane are two of the most prevalent and dangerous greenhouse gases.  Comparing these two gases can seem trivial because methane “readily undergoes combustion producing carbon dioxide and water”.  However, before methane undergoes this process, it exhibits many different chemical properties when compared with carbon dioxide.  First, carbon dioxide has a global warming potential of 1, while methane's is much higher at 28-36 over 100 years.  Another characteristic that can be compared is their lifetime.  Methane’s lifetime, on average, is about a decade, but carbon dioxides lifetime can be centuries long.

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Methane is commonly overlooked because of the national and international focus on carbon dioxide.  Even though carbon dioxide is emitted in greater quantities and persists in the atmosphere longer, methane is more damaging than carbon dioxide.  Methane is a colorless, odorless, tasteless gas.  A methane molecule is composed of one carbon atom covalently bonded to four hydrogen atoms and thus has a chemical formula of CH4.  Methane is a greenhouse gas (GHG) and generates 75% of natural gas.  CH4 also accounts for about 20% of global emissions.

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Methane is produced less and has an inferior concentration in the atmosphere compared to carbon dioxide, however methane is considered more dangerous.  It is widely agreed that “methane is more than 25 times as potent as carbon dioxide at trapping heat in the atmosphere," meaning that some of the heat that would usually be cast out back into space is getting trapped in the Earth's atmosphere.  This additional heat manifests itself as global warming or climate change.  Carbon dioxide has a much longer lifetime than methane.  However, carbon dioxide's long lifetime cannot compete with methane, because “pound for pound, the comparative impact of CH4 on climate change is more than 25 times greater than CO2 over a 100-year period.”

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Methane poses other dangers, besides the effects on the atmosphere.  Methane is an extremely flammable gas, as well as an explosion hazard in enclosed areas.  If ignited, poisonous gases will be produced in the fire.  During these fires, there is also a possibility that the containers may explode.  If people are not prepared for this, they could become gravely injured.  Additionally, methane is an asphyxiant and depletes oxygen in enclosed areas causing “suffocation with symptoms of a headache, dizziness, weakness, nausea, vomiting, loss of coordination and judgment, increased breathing rate and loss of consciousness."

 

Methane can be emitted from a variety of anthropogenic and natural sources.  An anthropogenic source is one that is human-influenced, such as landfills and agricultural plantations.  In the United States, landfills account for approximately 20.2% of total anthropogenic methane emissions.  At this percent, methane emissions exclusively from landfills are the third largest source of CH4 emissions in the United States.  Methane is produced through the decomposition of organic waste under anaerobic conditions.  A more detailed explanation of this process is provided by the Inventory of U.S. Greenhouse Gas Emissions and Sinks: “After being placed in a landfill, organic waste (such as paper, food scraps, and yard trimmings) is initially decomposed by aerobic bacteria.  After the oxygen has been depleted, the remaining waste is available for consumption by anaerobic bacteria, which break down organic matter into substances such as cellulose, amino acids, and sugars.  These substances are further broken down through fermentation into gasses and short-chain organic compounds that form the substrates for the growth of methanogenic bacteria.  These methane (CH4) producing anaerobic bacteria convert the fermentation products into stabilized organic materials and biogas consisting of approximately 50 percent biogenic carbon dioxide (CO2) and 50 percent CH4, by volume.”