Atmospheric methane

[11] Since 1750 methane has contributed 3% of greenhouse gas (GHG) emissions in terms of mass[12] but is responsible for approximately 23% of radiative or climate forcing.

[10] Radiative or climate forcing is the scientific concept used to measure the human impact on the environment in watts per square meter (W/m2).

[13] Collins et al. said that CH4 mitigation that reduces atmospheric methane by the end of the century, could "make a substantial difference to the feasibility of achieving the Paris climate targets", and would provide us with more "allowable carbon emissions to 2100".

[6] In addition to the direct heating effect and the normal feedbacks, the methane breaks down to carbon dioxide and water.

Ramanathan (1998)[28] notes that both water and ice clouds, when formed at cold lower stratospheric temperatures, are extremely efficient in enhancing the atmospheric greenhouse effect.

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.

[33][34] Reducing methane emissions by capturing and utilizing the gas can produce simultaneous environmental and economic benefits.

[31][35] 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.

[citation needed] [43] In 2011, cavity ring-down spectroscopy was the most widely used IR absorption technique of detecting methane.

[52] The annual average for methane (CH4) was 1866 ppb in 2019 and scientists reported with "very high confidence" that concentrations of CH4 were higher than at any time in at least 800,000 years.

[14] The largest annual increase occurred in 2021 with current concentrations reaching a record 260% of pre-industrial—with the overwhelming percentage caused by human activity.

Working with over fifty international research institutions and 100 stations globally, it updates the methane budget every few years.

[60] Through this CH4 oxidation process, atmospheric methane is destroyed and water vapor and carbon dioxide are produced.

While this decreases the concentration of methane in the atmosphere, it is unclear if this leads to a net positive increase in radiative forcing because both water vapor and carbon dioxide are more powerful GHGs factors in terms of affecting the warming of Earth.

This additional water vapor in the stratosphere caused by CH4 oxidation, adds approximately 15% to methane's radiative forcing effect.

[62][63] Both water and ice clouds, when formed at cold lower stratospheric temperatures, have a significant impact by increasing the atmospheric greenhouse effect.

[62][63] Methane also affects the degradation of the ozone layer—the lowest layer of the stratosphere from about 15 to 35 kilometers (9 to 22 mi) above Earth, just above the troposphere.

Their climate models based on data available at that time, had indicated that carbon dioxide and methane enhanced the transport of water into the stratosphere.

[65] Atmospheric methane could last about 120 years in the stratosphere until it is eventually destroyed through the hydroxyl radicals oxidation process.

[68][69][67] However, the average time that the atmosphere will be affected by the emission of that molecule before reaching equilibrium – known as its 'perturbation lifetime' – is approximately twelve years.

[73] With a lower water table, any methane in the soil has to make it past the methanotrophic bacteria before it can reach the atmosphere.

Their presence can often efficiently limit emissions from sources such as the underwater permafrost in areas like the Laptev Sea.

[89] In 2001, NASA's Goddard Institute for Space Studies and Columbia University's Center for Climate Systems Research scientists confirmed that other greenhouse gases apart from carbon dioxide were important factors in climate change in research presented at the annual meeting of the American Geophysical Union (AGU).

They posited that there was a vast release of methane that had previously been kept stable through "cold temperatures and high pressure...beneath the ocean floor".

A 2009 journal article in Science, confirmed NASA research that the contribution of methane to global warming had previously been underestimated.