section_path: Environmental effects/Greenhouse effect and natural gas release
section_name: Greenhouse effect and natural gas release
paragraph_text: Greenhouse effect and natural gas release
  
  Human activity is responsible for about 60% of all methane emissions and for most of the resulting increase in atmospheric methane. Natural gas is intentionally released or is otherwise known to leak during the extraction, storage, transportation, and distribution of fossil fuels. Globally, methane accounts for an estimated 33% of anthropogenic greenhouse gas warming. The decomposition of municipal solid waste (a source of landfill gas) and wastewater account for an additional 18% of such emissions. These estimates include substantial uncertainties which should be reduced in the near future with improved satellite measurements, such as those planned for MethaneSAT.
  
  After release to the atmosphere, methane is removed by gradual oxidation to carbon dioxide and water by hydroxyl radicals (OH) formed in the troposphere or stratosphere, giving the overall chemical reaction CH + 2 O → CO + 2 H O. While the lifetime of atmospheric methane is relatively short when compared to carbon dioxide, with a half-life of about 7 years, it is more efficient at trapping heat in the atmosphere, so that a given quantity of methane has 84 times the global-warming potential of carbon dioxide over a 20-year period and 28 times over a 100-year period. Natural gas is thus a potent greenhouse gas due to the strong radiative forcing of methane in the short term, and the continuing effects of carbon dioxide in the longer term.
  
  Targeted efforts to reduce warming quickly by reducing anthropogenic methane emissions is a climate change mitigation strategy supported by the Global Methane Initiative.