page_title: Methane
section_title: Atmospheric methane
hierarchical_section_title: Methane / Occurrence / Atmospheric methane
caption_attribution_description: English: Methane concentrations
context_page_description: Methane is a chemical compound with the chemical formula CH₄. It is a group-14 hydride and the simplest alkane, and is the main constituent of natural gas. The relative abundance of methane on Earth makes it an attractive fuel, although capturing and storing it poses challenges due to its gaseous state under normal conditions for temperature and pressure.
  Naturally occurring methane is found both below ground and under the seafloor, and is formed by both geological and biological processes. The largest reservoir of methane is under the seafloor in the form of methane clathrates. When methane reaches the surface and the atmosphere, it is known as atmospheric methane. The Earth's atmospheric methane concentration has increased by about 150% since 1750, and it accounts for 20% of the total radiative forcing from all of the long-lived and globally mixed greenhouse gases. Methane has also been detected on other planets, including Mars, which has implications for astrobiology research.
context_section_description: In 2010, methane levels in the Arctic were measured at 1850 nmol/mol.  This level is over twice as high as at any time in the last 400,000 years. Historic methane concentrations in the world's atmosphere have ranged between 300 and 400 nmol/mol during glacial periods commonly known as ice ages, and between 600 and 700 nmol/mol during the warm interglacial periods. The Earth's oceans are a potential important source of Arctic methane.
  Methane is an important greenhouse gas with a global warming potential of 34 compared to CO₂ (potential of 1) over a 100-year period, and 72 over a 20-year period.
  The Earth's atmospheric methane concentration has increased by about 150% since 1750, and it accounts for 20% of the total radiative forcing from all of the long-lived and globally mixed greenhouse gases (these gases don't include water vapor which is by far the largest component of the greenhouse effect).
  From 2015 to 2019 sharp rises in levels of atmospheric methane have been recorded.  In February 2020, it was reported methane emissions from the fossil fuel industry may have been significantly underestimated.
  Climate change can increase atmospheric methane levels by increasing methane production in natural ecosystems, forming a Climate change feedback.
caption: Methane concentration evolution from 1987 to October 2019 at Mauna Loa (Hawaii).
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