What is methane and where does it come from?

Methane is a gas composed of carbon and hydrogen. It has the chemical formula CH4. Methane originates from several different sources.

  • Microbial methane is produced through biologic decomposition of organic matter at shallow depths and without extensive heating.  Swamps, landfills, glacial or other deposits, and even shallow bedrock are some settings where microbial methane can form.
  • Thermogenic methane is derived over millions of years by processes deep underground that produce fossil fuels, such as coal deposits and oil and natural gas accumulations. It is produced from organic matter that undergoes a transformation under high temperature and pressure.

Scientists run tests that can help distinguish microbial methane from thermogenic methane.