Is Methane a Greenhouse Gas?

Methane is a greenhouse gas, and pound for pound it traps much more outgoing heat than carbon dioxide does. How much more depends on the number of years you measure across, which is why the multiplier attached to methane changes from one report to the next.

Why Is Methane a Greenhouse Gas?

Methane traps heat because it absorbs infrared light, which is the form energy takes when it leaves the planet. Sunlight arrives as a mix of visible, ultraviolet, and infrared, but Earth radiates that energy back out almost entirely as infrared. Methane intercepts part of it on the way.

A molecule can only absorb light at wavelengths that match its own vibration, and methane’s structure gives it a long list of matches.

Methane (CH₄) is a single carbon atom with four hydrogens attached to it. CO₂ is a single carbon with two oxygens, arranged in a straight line. Four hydrogens can bend, stretch, and twist in far more ways than a three-atom line can, and each of those motions pairs with a different wavelength of infrared light.

Absorbing that energy isn’t the end of the process. The molecule jumps to an excited state, then sheds the extra energy as heat, and some of that heat travels back toward the surface instead of out to space.

The same physics explains why most of the air traps no heat whatsoever. Nitrogen and oxygen account for about 99% of the atmosphere, but each molecule is two identical atoms, and no vibration of that pair shifts the balance of charge inside it. With no shifting electric field, there’s nothing for infrared light to interact with, and the energy passes straight through. CO₂ and methane both generate that field as they bend and stretch, which is what puts them in a different category.

How Much More Heat Does Methane Trap Than Carbon Dioxide?

The instant-by-instant answer is about 120 times. But almost nobody uses that number because methane doesn’t stay in the atmosphere long enough for it to hold.

A methane molecule lasts roughly 12 years before reactions with hydroxyl radicals break it down into CO₂ and water vapor. Carbon dioxide has no equivalent removal step, and a large share of any CO₂ release stays airborne for centuries.

So the comparison hinges entirely on the length of the window you measure across. The standard metric for this is global warming potential (GWP), which totals up the heat a gas traps over a fixed number of years and scores it against the same mass of CO₂.

Measured over 20 years, methane scores around 80. Measured over 100 years, it drops to somewhere between 28 and 30.

The shorter window catches methane while it’s still doing nearly all of its work. The longer one spreads that same burst of warming across decades when the methane is long gone and the CO₂ it was compared against is still absorbing.

How Much of Today’s Warming Comes From Methane?

Methane is responsible for roughly 30% of the global temperature rise since pre-industrial times, which puts it second among greenhouse gases behind carbon dioxide. That is according to the Global Methane Assessment published by the UN Environment Programme and the Climate and Clean Air Coalition.

Atmospheric methane averaged about 1,938 parts per billion in April 2026, according to NOAA’s record of global atmospheric methane. Before industrialization, it sat near 720 parts per billion, so the concentration has nearly tripled.

Put in the units carbon dioxide is usually measured in, 1,938 parts per billion works out to under 2 parts per million, and CO₂ runs above 400 parts per million. So, methane is more than 200 times scarcer and still accounts for close to a third of the warming.

The growth rate has slowed down recently, though. Global methane rose 5.34 parts per billion during 2025, well below the record 17.69 parts per billion added in 2021.

How Does Methane Compare Against Other Greenhouse Gases?

Methane places second by total contribution to warming and somewhere in the middle by potency per unit of mass. Measured over a century, nitrous oxide traps roughly nine times more heat per pound than methane, and sulfur hexafluoride (SF₆) traps more than 800 times more.

Potency alone doesn’t decide the ranking, though, and the per-pound figures above describe a fresh release rather than the gas already in the air. Nitrous oxide is present at about 340 parts per billion and SF₆ at roughly 13 parts per trillion, both well below methane’s level.

The measure that captures actual heating is radiative forcing, which accounts for how much of each gas has built up and how strongly it absorbs at that level. Methane’s is roughly 2.5 times that of nitrous oxide’s, and second only to carbon dioxide’s.

Why Do Methane Emissions Totals Vary So Much?

Two facilities can release identical amounts of methane and file very different numbers, because the multiplier applied to methane isn’t fixed across frameworks. Both the time horizon and the origin of the gas change it.

The EPA’s Greenhouse Gas Reporting Program uses 28. That value comes from Table A-1 of the federal greenhouse gas reporting rule, which the agency updated to the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report figures effective January 2025. Reporters previously used 25.

One metric ton of methane becomes 28 metric tons of carbon dioxide equivalent (CO₂e), and the CO₂e total is what gets summed against thresholds and filed.

Other frameworks land elsewhere. The IPCC’s Sixth Assessment Report splits methane by origin, assigning about 29.8 to fossil methane from oil, gas, and coal systems and about 27.0 to biogenic methane from landfills, livestock, and digesters. Corporate reporting under the Greenhouse Gas Protocol may draw on either assessment depending on the framework in play. Every one of those figures is a 100-year value, and a calculation run on a 20-year basis roughly triples the result, because the longer window mostly grows the carbon dioxide baseline rather than methane’s side of the comparison.

The EPA has been reworking the reporting program’s scope and deadlines, so the requirement that governed one year’s filing may not govern the next. Anyone whose facility reports methane should confirm the rule in force rather than reusing the prior basis.

Tyler O'Brien

Tyler is a results-driven marketing professional specializing in the industrial gases and equipment industry, bringing his 10 years of technical expertise and digital marketing acumen to the complex industrial gas B2B environment.