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. During 2019, about 60% (360 million tons) of methane released globally was from human activities, while natural sources contributed about 40% (230 million tons). During 2024, it was estimated that 610 million tons of methane were released globally with nearly two-thirds of it being from human activity. Reducing methane emissions by capturing and utilizing the gas can produce simultaneous environmental and economic benefits.
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.Borunda, A. (2021, May 03). Methane facts and information. Retrieved April 6, 2022, from 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. As of 2024, the United States is the world's top methane emitter from oil and gas, while China stands at the top for methane emissions from coal. The International Energy Agency (IEA) highlights that abandoned coal mines and oil and gas wells have become significant sources of methane emissions. If considered a country, these emissions would rank as the fourth-largest globally, surpassing those of Iran. The IEA estimates that addressing over 8 million abandoned onshore oil and gas sites would cost about $100 billion.
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 A single cow can make up to 99 kg of methane gas per year. Ruminant livestock can produce 250 to 500 L of methane per day.
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.
The world's wetlands contribute about three-quarters (75%) of the enduring natural sources of methane. Seepages from near-surface hydrocarbon and clathrate hydrate deposits, volcanic releases, wildfires, and termite emissions account for much of the remainder. Contributions from the surviving wild populations of ruminant mammals are vastly overwhelmed by those of cattle, humans, and other livestock animals.
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".
Atmospheric concentration and warming influence
The atmospheric methane (CH4) concentration is increasing and exceeded 1931 parts per billion in 2024, equal to 2.6 times the pre-industrial level. The methane itself causes direct radiative forcing that is second only to that of carbon dioxide (CO2). Due to interactions with oxygen compounds stimulated by sunlight, CH4 can also increase the atmospheric presence of shorter-lived ozone and water vapour, themselves potent warming gases: atmospheric researchers call this amplification of methane's near-term warming influence indirect radiative forcing. When such interactions occur, longer-lived and less-potent CO2 is also produced. Including both the direct and indirect forcings, the increase in atmospheric methane is responsible for about one-third of near-term global heating.
Though methane causes far more heat to be trapped than the same mass of carbon dioxide, less than half of the emitted CH4 remains in the atmosphere after a decade. On average, carbon dioxide warms for much longer, assuming no change in rates of carbon sequestration. The global warming potential (GWP) is a way of comparing the warming due to other gases to that from carbon dioxide, over a given time period. Methane's GWP20 of 85 means that a ton of CH4 emitted into the atmosphere creates approximately 85 times the atmospheric warming as a ton of CO2 over a period of 20 years.Myhre, G., D. Shindell, F.-M. Bréon, W. Collins, J. Fuglestvedt, J. Huang, D. Koch, J.-F. Lamarque, D. Lee, B. Mendoza, T. Nakajima, A. Robock, G. Stephens, T. Takemura and H. Zhang (2013) "Anthropogenic and Natural Radiative Forcing". Table 8.7 on page 714. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.). Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. Anthropogenic and Natural Radiative Forcing On a 100-year timescale, methane's GWP100 is in the range of 28–34.
Methane emissions are important as reducing them can buy time to tackle carbon emissions.
Overview of emission sources
Biogenic methane is actively produced by microorganisms in a process called methanogenesis. Under certain conditions, the process mix responsible for a sample of methane may be deduced from the ratio of the isotopes of carbon, and through analysis methods similar to carbon dating.
Anthropogenic
, emission volumes from some sources remain more uncertain than others; due in part to localized emission spikes not captured by the limited global measurement capability. The time required for a methane emission to become well-mixed throughout earth's troposphere is about 1–2 years.
Satellite data indicate over 80% of the growth of methane emissions during 2010–2019 are tropical terrestrial emissions.
There is accumulating research and data showing that oil and gas industry methane emissions – or from fossil fuel extraction, distribution and use – are much larger than thought.
Category Major Sources IEA Annual Emission 2023(Million Tons) Fossil fuels Gas distribution 29 Oil wells 49* Coal mines 40 Biofuels Anaerobic digestion 10 Industrial agriculture Enteric fermentation 142 Rice paddies Manure management Biomass Biomass burning 10 Consumer waste Solid wasteLandfill gas 71 Wastewater Total anthropogenic 351 * An additional 100 million tons (140 billion cubic meters) of gas is flared each year from oil wells.Additional References:
Natural
Natural sources have always been a part of the methane cycle. Wetland emissions have been declining due to draining for agricultural and building areas.
Category Major Sources IEA Annual Emission 2023(Million Tons) Wetlands Wetland methane 194 Other natural Geologic seepagesVolcanic gas 39 Arctic methane emissions Ocean sediments Wildfires Termites Total natural 233 Additional References:
Methanogenesis Most ecological emissions of methane relate directly to methanogens generating methane in warm, moist soils as well as in the digestive tracts of certain animals. Methanogens are methane producing microorganisms. In order to produce energy, they use an anaerobic process called methanogenesis. This process is used in lieu of aerobic, or with oxygen, processes because methanogens are unable to metabolise in the presence of even small concentrations of oxygen. When acetate is broken down in methanogenesis, the result is the release of methane into the surrounding environment.
Methanogenesis, the scientific term for methane production, occurs primarily in anaerobic conditions because of the lack of availability of other oxidants. In these conditions, microscopic organisms called archaea use acetate and hydrogen to break down essential resources in a process called fermentation.
Acetoclastic methanogenesis – certain archaea cleave acetate produced during anaerobic fermentation to yield methane and carbon dioxide.
H3C-COOH → CH4 + CO2
Hydrogenotrophic methanogenesis – archaea oxidize hydrogen with carbon dioxide to yield methane and water.
4H2 + CO2 → CH4 + 2H2O
While acetoclastic methanogenesis and hydrogenotrophic methanogenesis are the two major source reactions for atmospheric methane, other minor biological methane source reactions also occur. For example, it has been discovered that leaf surface wax exposed to UV radiation in the presence of oxygen is an aerobic source of methane.
Natural methane cycles
Its concentration is higher in the Northern Hemisphere since most sources (both natural and human) are located on land and the Northern Hemisphere has more land mass. The concentrations vary seasonally, with, for example, a minimum in the northern tropics during April−May mainly due to removal by the hydroxyl radical.
For example, plants that produce methane can emit as much as two to four times more methane during the day than during the night. This is directly related to the fact that plants tend to rely on solar energy to enact chemical processes.
Wetlands In wetlands, where the rate of methane production is high, plants help methane travel into the atmosphere—acting like inverted lightning rods as they direct the gas up through the soil and into the air. They are also suspected to produce methane themselves, but because the plants would have to use aerobic conditions to produce methane, the process itself is still unidentified, according to a 2014 Biogeochemistry article.
A 1994 article on methane emissions from northern wetlands said that since the 1800s, atmospheric methane concentrations increased annually at a rate of about 0.9%.
Human-caused methane emissions
The AR6 of the IPCC said, "It is unequivocal that the increases in atmospheric carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) since the pre-industrial period are overwhelmingly caused by human activities." Atmospheric methane accounted for 20% of the total radiative forcing (RF) from all of the long-lived and globally mixed greenhouse gases.
According to the 2021 assessment by the Climate and Clean Air Coalition (CCAC) and the United Nations Environment Programme (UNEP) over 50% of global methane emissions are caused by human activities in fossil fuels (35%), waste (20%), and agriculture (40%). The oil and gas industry accounts for 23%, and coal mining for 12%. Twenty percent of global anthropogenic emissions stem from landfills and wastewater. Manure and enteric fermentation represent 32%, and rice cultivation represents 8%.
The most clearly identified rise in atmospheric methane as a result of human activity occurred in the 1700s during the industrial revolution. During the 20th centurymainly because of the use of fossil fuelsconcentration of methane in the atmosphere increased, then stabilized briefly in the 1990s, only to begin to increase again in 2007. After 2014, the increase accelerated and by 2017, reached 1,850 parts per billion. From 2020 to 2024, the increase continued, going from 1875 ppb to 1931 ppb in 2020 and 2024 respectively.
Increases in methane levels due to modern human activities arise from a number of specific sources including industrial activity; from extraction of oil and natural gas from underground reserves; transportation via pipeline of oil and natural gas; and thawing permafrost in Arctic regions, due to global warming which is caused by human use of fossil fuels.
The primary component of natural gas is methane, which is emitted to the atmosphere in every stage of natural gas "production, processing, storage, transmission, and distribution".
Emissions due to oil and gas extraction