Methane Emissions
Methane is the second-largest contributor to human-caused warming after CO₂, but it behaves differently in the atmosphere — short-lived and much more potent per tonne over short horizons. The accounting choice between a 20-year and a 100-year warming horizon can roughly halve or double the apparent size of the methane problem.
Last reviewed on 2026-04-27.
Where methane comes from
Energy: oil, gas, and coal
Fossil-fuel operations leak methane at the well, the pipeline, the compressor station, the LNG terminal, and the abandoned coal mine. The IEA’s Methane Tracker breaks the energy total into oil, natural gas, and coal sub-sources. Oil-and-gas methane is concentrated in a relatively small number of producing basins; venting and flaring practices vary widely by operator and country, which is one reason policy attention has focused here — the abatement-cost curve is unusually flat and many measures pay for themselves in saved gas.
Agriculture: livestock and rice
Enteric fermentation in ruminants — cattle, sheep, goats, buffalo — and manure management produce most of agricultural methane. Flooded rice paddies are the other major source, because anaerobic conditions in the paddy water let methanogens convert organic matter to CH₄. Agricultural methane is generally harder and more expensive to abate than energy methane, because it is distributed across many small sources and intersects with food security and rural livelihoods.
Waste: landfills and wastewater
Solid-waste landfills generate methane as buried organic material decomposes anaerobically; wastewater treatment plants and open sewage systems produce methane in similar conditions. Landfill methane can be captured and either flared or used to generate electricity; the share of landfills with capture systems varies enormously between high-income and low-income countries. As cities grow, the waste-sector source grows with them unless capture and source-separation programmes catch up.
Natural sources
Wetlands, termites, and geological seepage emit methane naturally. They are part of the global atmospheric budget but not counted as anthropogenic emissions. The line between natural and anthropogenic gets blurry where human activity changes natural sources — drained peatlands, thawing permafrost in a warmer climate, and reservoirs created by hydropower dams all complicate that boundary.
The GWP horizon problem
Why one tonne of methane is not one tonne of CO₂
Methane traps far more heat than CO₂ per unit mass while it is in the atmosphere, but it stays for roughly a decade rather than the centuries CO₂ does. Global Warming Potential (GWP) is the conversion factor that makes the two comparable on a chosen time horizon. Over 100 years (GWP-100), one tonne of methane is treated as equivalent to roughly thirty times one tonne of CO₂ in IPCC AR6 conventions. Over 20 years (GWP-20), the factor is several times larger because most of methane’s warming impact lands in the early decades.
Why the choice matters
National inventories under the UNFCCC use GWP-100 by convention. Reports focused on near-term temperature peaks — particularly those discussing the 1.5°C horizon — increasingly cite GWP-20 to make the short-term leverage of methane visible. The same emissions look very different on the two scales, which is why methane charts that omit the horizon are sometimes the most misleading climate charts in circulation. A serious comparison either fixes the horizon or shows both.
An alternative: GWP*
Researchers have proposed GWP* (“GWP-star”) as a metric that better reflects the temperature response to short-lived gases like methane: a stable rate of methane emissions has a roughly stable temperature contribution, and increases or decreases drive temperature changes more directly than the cumulative GWP-100 framing suggests. GWP* is not used in official inventories yet but appears in academic and policy discussions when the goal is to model temperature pathways rather than equivalent-tonne accounting.
Inventory versus atmospheric measurement
Bottom-up inventories (countries adding up their reported emissions) and top-down measurements (satellites and aircraft watching the atmosphere) consistently disagree on global methane, with top-down totals generally larger. The gap has narrowed as inventory methods improved, but it has not closed. Detection technologies — TROPOMI on Sentinel-5P, the privately funded MethaneSAT, GHGSat’s commercial fleet, and Carbon Mapper — are pulling national figures toward what the atmosphere shows. National inventories that have ground-truthed against satellite observations have, in several cases, revised oil-and-gas methane upward by significant margins.
Reading methane statistics carefully
Always check the horizon
A methane share of total greenhouse-gas emissions on GWP-100 is roughly half its share on GWP-20. Both are correct in their frame; mixing them in one chart is not.
Distinguish energy from agriculture
Energy methane and agricultural methane have very different abatement-cost curves and policy levers. A composite “methane emissions” figure can hide which sources are actually movable.
Treat super-emitters as outliers
Satellite detection has shown that a small share of facilities accounts for an outsized share of oil-and-gas methane. Average emission factors hide this skew; super-emitter inventories are increasingly the focus of policy.
Watch revisions
Methane inventories revise more than CO₂ inventories, especially as satellite data is incorporated. A jump in a country’s reported methane is often a methodological revision rather than a real change in emissions.
Sources
The standard references on this topic are the IEA Methane Tracker (energy-sector methane, country-level estimates), the IPCC AR6 Working Group I chapter on the global carbon cycle and short-lived climate forcers, EDGAR (the European Commission JRC’s emissions database) and the FAO FAOSTAT for agricultural methane, the UN Climate & Clean Air Coalition’s Global Methane Assessment, the Global Carbon Project methane budget, and satellite products from TROPOMI, MethaneSAT, GHGSat and Carbon Mapper. Country UNFCCC inventories are the official record but should be read alongside top-down sources for plausibility.
Methane is part of the broader emissions picture covered in emissions by sector, intersects with the production discussed under fossil fuels, and connects to public-health outcomes through air pollution via tropospheric ozone formation.