Methane emissions

Sources of methane emissions due to human activity (year 2020 estimates)[1]

  Fossil Fuel Use (33%)
  Animal Agriculture (30%)
  Plant Agriculture (18%)
  Waste (15%)
  All Other (4%)

Increasing methane emissions are a major contributor to the rising concentration of greenhouse gases in Earth's atmosphere, and are responsible for up to one-third of near-term global heating.[1][2] During 2019, about 60% (360 million tons) of methane released globally was from human activities, while natural sources contributed about 40% (230 million tons).[3][4] Reducing methane emissions by capturing and utilizing the gas can produce simultaneous environmental and economic benefits.[1][5]

Since the Industrial Revolution, concentrations of methane in the atmosphere have more than doubled, and about 20 percent of the warming the planet has experienced can be attributed to the gas.[6] About one-third (33%) of anthropogenic emissions are from gas release during the extraction and delivery of fossil fuels; mostly due to gas venting and gas leaks from both active fossil fuel infrastructure and orphan wells.[7] Russia is the world's top methane emitter from oil and gas.[8][9]

Animal agriculture is a similarly large source (30%); primarily because of enteric fermentation by ruminant livestock such as cattle and sheep. According to the Global Methane Assessment published in 2021, methane emissions from livestock (including cattle) are the largest sources of agricultural emissions worldwide[10] A single cow can make up to 99 kg of methane gas per year.[11] Ruminant livestock can produce 250 to 500 L of methane per day.[12]

Human consumer waste flows, especially those passing through landfills and wastewater treatment, have grown to become a third major category (18%). Plant agriculture, including both food and biomass production, constitutes a fourth group (15%), with rice production being the largest single contributor.[1][13]

The world's wetlands contribute about three-quarters (75%) of the enduring natural sources of methane.[3][4] Seepages from near-surface hydrocarbon and clathrate hydrate deposits, volcanic releases, wildfires, and termite emissions account for much of the remainder.[13] Contributions from the surviving wild populations of ruminant mammals are vastly overwhelmed by those of cattle, humans, and other livestock animals.[14]

The Economist recommended setting methane emissions targets as a reduction in methane emissions would allow for more time to tackle the more challenging carbon emissions".[15][16]

  1. ^ a b c d "Global Methane Emissions and Mitigation Opportunities" (PDF). Global Methane Initiative. 2020.
  2. ^ IPCC Fifth Assessment Report - Radiative Forcings (AR5 Figure SPM.5) (Report). Intergovernmental Panel on Climate Change. 2013.
  3. ^ a b "Sources of methane emissions". International Energy Agency. Retrieved 2020-08-20.
  4. ^ a b "Global Carbon Project (GCP)". www.globalcarbonproject.org. Retrieved 2019-07-25.
  5. ^ Methane - A compelling case for action (Report). International Energy Agency. 2020-08-20.
  6. ^ Borunda, A. (2021, May 03). Methane facts and information. Retrieved April 6, 2022, from [1]
  7. ^ Leber, Rebecca (2021-08-12). "It's time to freak out about methane emissions". Vox. Retrieved 2022-01-05.
  8. ^ Trakimavicius, Lukas. "Putting a lid on Russia's planet-heating methane emissions". EurActiv. Retrieved 2023-07-26.
  9. ^ Timothy Puko (19 October 2021). "Who Are the World's Biggest Climate Polluters? Satellites Sweep for Culprits". The Wall Street Journal. Retrieved 19 October 2021. Russia is the world's top source of methane emissions from the oil-and-gas industry
  10. ^ "Yes, cattle are the top source of methane emissions in the US". verifythis.com. 2021-11-12. Retrieved 2024-02-26.
  11. ^ "Cows and Climate Change". UC Davis. 2019-06-27. Retrieved 2024-02-26.
  12. ^ Johnson, K A (1995-08-01). "Methane emissions from cattle". academic.oup.com. Retrieved 2023-04-27.
  13. ^ a b "Methane, explained". National Geographic. nationalgeographic.com. 2019-01-23. Archived from the original on April 17, 2019. Retrieved 2019-07-25.
  14. ^ Vaclav Smil (2017-03-29). "Planet of the Cows". IEEE Spectrum. Retrieved 2020-09-08.
  15. ^ "Governments should set targets to reduce methane emissions". The Economist. 2021-03-31. ISSN 0013-0613. Retrieved October 10, 2021.
  16. ^ Terazono, Emiko; Hodgson, Camilla (2021-10-10). "How methane-producing cows leapt to the frontline of climate change". Financial Times. Retrieved October 10, 2021.