What you need to know about methane
Methane (CH₄) is a potent greenhouse gas with an atmospheric lifetime much shorter than carbon dioxide (CO₂). Methane emissions have substantially contributed to observed climate change over the past 150 years. Methane also has other implications for the climate system, human health, air pollution, and agriculture.
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The International Panel on Climate Change Sixth Assessment Report estimates that of the total 1.1 degrees C of warming in 2010-2019 relative to 1850-1900, approximately 0.5 degrees C is attributable to increased methane emissions.
Since the pre-industrial period, atmospheric methane concentrations have nearly tripled. It is well established that this dramatic increase has been driven by anthropogenic activity (Jackson et al., 2020; UNEP and CCAC, 2021; Skeie et al., 2023),
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On a molecule-by-molecule basis, methane is a much more potent greenhouse gas than carbon dioxide, with an estimated 81-83 times larger 20-yr global warming potential and 27-30 times larger 100-yr global warming potential relative to that of carbon dioxide (Forster et al., 2021). However, it is important to note that methane makes up a make smaller fraction by volume of concentration in the atmosphere or in anthropogenic emissions than carbon dioxide.
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Methane has an atmospheric lifetime of approximately a decade (Stevenson et al., 2020; Szopa et al., 2021), much shorter than that of carbon dioxide. This is because methane it is more chemically reactive in the atmosphere and is removed through faster processes. As a consequence, reductions in methane emissions are expected to quickly reduce the rate of global warming within a decade (UNEP and CCAC, 2021; Ocko et al., 2021).
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According to the UNEP 2021 Global Methane Assessment: “Ozone attributable to anthropogenic methane emissions causes approximately half a million premature deaths per year globally and harms ecosystems and crops by suppressing growth and diminishing production.”
Ozone exposure primarily increase mortality due to impacts on the respiratory and cardiovascular system. Including the health impacts of methane-related ozone would more than double the current social cost of methane used by the US government (McDuffie et al., 2023).
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Due to its chemical impacts in the atmosphere, methane will lead to increased concentrations of carbon dioxide, water vapour and ozone (both stratospheric and tropospheric) - all important greenhouse gases. This can increase the radiative forcing attributed to methane by more than 50% (Szopa et al., 2021).
Due to its effects on atmospheric chemistry, in particular stratospheric water vapour and stratospheric ozone, methane has an important role in stratospheric climate.
The fingerprint of methane on the atmospheric circulation and regional climate is less clear than for carbon dioxide, as it much less studied.
Since the pre-industrial era, atmospheric methane concentrations have nearly tripled (Canadell et al, 2021). According to ice core data, modern atmospheric methane concentrations are higher than at any time over the past 800,000 years (Canadell et al, 2021). Over the past decade, concentrations have surged to new record highs (Lan et al, 2025). The precise drivers of the plateau in methane levels in the early 2000s and the recent rise are areas of active scientific research (Turner et al, 2019; Oh et al, 2022; Qu et al, 2022).