Methane is a trace constituent in earth's atmosphere that both occurs naturally and is manmade. Recently, scientists have linked the increased release of methane into the atmosphere with global warming.
Methane (CH4) is a colorless, odorless, and explosive gas that occurs naturally in the environment; underground, in the atmosphere, and in the world's oceans. Methane is formed by the decomposition of organic materials and is therefore common in marshes and estuaries. Over the past century, methane gas concentrations in the atmosphere have increased tremendously, in large part due to human activities such as man-made landfills, the cultivation of large numbers of livestock, natural gas and oil systems, coal mining, septic systems and rice farming.
Small-Scale Environmental Effects
As centers for decomposition, landfills release large quantities of methane gas. This methane gas buildup from the landfills poses a potential explosion hazard and creates resulting environmental damage. However, aside from this environmental hazard, methane has been determined to have little photochemical reactivity and poses negligible risk to the formation of harmful ground-level pollutants.
Large-Scale Environmental Effects
Methane exists in the environment as a greenhouse gas that has been linked to global warming. After carbon dioxide, methane is the second most important greenhouse gas. Methane's warming effect is 21 times greater than that of carbon dioxide; however, it stays in the atmosphere for a significantly shorter period of time.
The release of methane gas into the atmosphere increased dramatically over the past century. However, recent measures have been taken to decrease the human-induced emissions of methane gas in the effort to reduce global warming, including a commitment under the United Nations Framework Convention on Climate Change to reduce methane emissions. For example, vapor recovery systems are being developed to capture methane gas in an effort to limit its escape into the atmosphere, and changes to livestock's diets are being tested to reduce methane emissions from livestock.