Global Methane Emissions

Global Methane Emissions 

Why in News?

  • Recently a study titled- “Wetland emission and atmospheric sink changes explain methane growth in 2020’, which states that low nitrogen oxide pollution and warming wetlands likely drove global methane emissions to record high levels in 2020.

Highlights

  • Global methane emissions reached roughly 15 parts per billion (ppb) in 2020 from 9.9 ppb in 2019.
  • In 2020, methane emissions from human activities decreased by 1.2 teragrams(Tg)per year.
  • Methane emissions from oil and natural gas decreased by 3.1Tg per year compared to 2019. Contributions from coal mining decreased by 1.3Tgper year. Fire emissions, too, dropped by 6.5 Tgper year.
  • Globally, fire emissions appear to have fallen in 2020 compared to 2019, the researchers wrote in the study.
  • Contributions from the agricultural sector went up by 1.6Tgper year.
  • Wetland emissions rose by 6.0Tgper year.
  • Waterlogged soils make conditions ripe for soil microorganisms, allowing them to produce more methane.
  • Nitrogen oxide levels fell by 6% in 2020 from 2019. Less nitrogen oxide pollution means less hydroxyl and more methane.
  • Nitrogen oxide enters the atmosphere from exhaust gasses of cars and trucks as well as electrical power generation plants.
  • Nitrogen oxide (NOx) can impact methane levels. In the troposphere — the upper part of the atmosphere — NOx combines with ozone to form hydroxyl radicals.
  • These radicals, in turn, remove 85 % of methane annually from the atmosphere.
  • The contribution of hydroxyl radicals in removing methane decreased by roughly 7.5Tg per year.
  • Roughly 53 % of the methane growth can be attributed to lower hydroxyl sink, and the remaining 47 % from natural sources, predominantly wetlands.
  • It can help unravel a puzzle concerning why globally methane increased when many other greenhouse gases like carbon dioxide decreased during 2020.
  • The results have significant implications for our ability to reliably predict methane changes in a future world with lower anthropogenic emissions of pollutants like nitrogen oxides and also if we have a wetter world.
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