BetterTwo greenhouse gases, two completely different clocks. That difference is the whole subject, and it is stated in one sentence by the World Meteorological Organization.
Methane's atmospheric lifetime is about nine years. Carbon dioxide, once emitted, affects the climate indefinitely.
Methane leaves. That is why cutting it produces a visible effect within a decade rather than a century, the UN Environment Programme puts a 45% cut this decade at keeping warming below an agreed threshold.
But the WMO adds, in the same bulletin: climate action urgently needs to focus on reducing fossil fuel CO₂ emissions, which represent the vast majority of overall emissions. Methane is a fast lever, not a substitute.
The differenceNine years against forever
Greenhouse gases are usually discussed by how much they warm. The more useful question is how long they stay.
On CO₂: “once CO₂ is emitted to the atmosphere, it affects climate indefinitely”its removal depends on exchanges between reservoirs on timescales running from years to hundreds of thousands of years.
On methane: “this is different from methane, whose atmospheric lifetime is about nine years due to its removal by chemical oxidation.”
Put plainly: a tonne of CO₂ emitted today is still shaping the climate when your great-grandchildren are old. A tonne of methane emitted today is, for the most part, gone before a child born this year finishes primary school.
Where it stands266% of the pre-industrial level
That 266% is the highest ratio of the three main greenhouse gases, methane has more than doubled relative to pre-industrial levels while CO₂ has risen by half. Yet methane accounts for about 16% of the radiative forcing from long-lived greenhouse gases, not the largest share. Concentration and effect are not the same measurement.
On its origin, the WMO splits it in two: about 40% natural, wetlands, termites, and about 60% human: ruminants, rice agriculture, fossil fuel exploitation, landfills and biomass burning.
One piece of encouraging news, stated precisely. The rise from 2023 to 2024 was 8 ppblower than the 11 ppb from 2022 to 2023, and lower than the average annual 10.6 ppb over the previous decade. Slowing a rise is not the same thing as a decline, and the level reached is still a record.
The consequenceWhy that makes it the fast lever
If a gas leaves in nine years, then stopping its emission shows up in the atmosphere within a decade. That is not true of CO₂, and it is the entire reason methane occupies so much space in climate policy.
“Cutting human-caused methane by 45% this decade would keep warming beneath a threshold agreed by world leaders.”
The assessment lists further benefits: rapid reduction in warming, which can help avoid dangerous climate tipping points; improved air quality that can save hundreds of thousands of lives; improved food security by preventing crop losses; and job creation.
A figure we are not going to give you. This assessment is usually quoted with a precise number of degrees avoided. We could not open its executive summary, the download is blocked, and the official French page does not state that figure; it says “a threshold agreed by world leaders”. So that is what we write. A number we have not read is a number we do not publish.
The other halfThe warning most articles skip
Everything above makes methane sound like the smart shortcut. The WMO anticipated that reading and blocked it, in the very paragraph that establishes the nine-year lifetime.
“While reducing CH₄ emissions is useful and necessary, climate action urgently needs to focus on reducing fossil fuel CO₂ emissions, which represent the vast majority of overall greenhouse gas emissions.”
The logic is not complicated once both halves are on the table. Methane is where you gain time. CO₂ is where you decide the destination. Cutting methane and leaving CO₂ alone buys a delay on a trajectory that has not changed.
Which is also why methane is attractive to anyone who would rather not touch fossil fuels. The gas that leaves is easier to talk about than the gas that stays.
What to keepWhat follows
- Two clocks, two jobs. Nine years and indefinitely are not two versions of the same problem, and no single measure addresses both.
- A concentration is not an effect. Methane is at 266% of its pre-industrial level and accounts for about 16% of long-lived greenhouse gas forcing. Both figures are true and they measure different things.
- Slower growth is not a decline. 8 ppb of increase is better than 11, and it is still an increase, on top of a record.
- Sixty per cent is human. Which is the part that can be acted on, ruminants, rice, fossil fuel operations, landfills, biomass burning.
The honest one-line summary is the one the WMO wrote itself: reducing methane is useful and necessaryand it is not where the urgency lies.
QuestionsFrequently asked questions
How long does methane stay in the air?
About nine years, according to the WMO Greenhouse Gas Bulletin. It is removed from the atmosphere by chemical oxidation. That is the decisive difference from carbon dioxide: the WMO writes that once emitted into the atmosphere, CO₂ “affects climate indefinitely”.
What share of warming does methane account for?
About 16% of radiative forcing from long-lived greenhouse gases, according to the WMO. Its concentration reached 1,942 parts per billion in 2024, or 266% of the pre-industrial level, compared with 152% for CO₂ and 125% for nitrous oxide.
Where does methane come from?
The WMO splits it this way: about 40% comes from natural sources, for instance wetlands and termites, and about 60% from human sources, ruminants, rice agriculture, fossil fuel exploitation, landfills and biomass burning.
Would cutting methane be enough?
No, and the WMO says so explicitly in the same bulletin: “while reducing CH₄ emissions is useful and necessary, climate action urgently needs to focus on reducing fossil fuel CO₂ emissions, which represent the vast majority of overall greenhouse gas emissions”. That is the sentence most articles about methane leave out.
So why does it get so much attention?
Because it is the only lever whose effect shows up quickly. The UN Environment Programme writes that cutting human-caused methane by 45% this decade would keep warming below a threshold agreed by world leaders. And the assessment lists other benefits: avoiding tipping points, air quality improvements that can save hundreds of thousands of lives, and fewer crop losses.
Is methane concentration still rising?
Yes, but the rise is slowing. From 2023 to 2024 it was 8 parts per billion, less than the 11 from 2022 to 2023, and less than the average annual 10.6 over the previous decade. Slowing a rise is not the same as a decline, and the level reached is still a record.
Read nextRelated
Sources
- WMO Greenhouse Gas Bulletin no. 21, World Meteorological Organization, October 2025 (PDF)
- Global Methane Assessment, UN Environment Programme and CCAC, 6 May 2021
About this article. General and educational information. The concentrations quoted are from WMO Bulletin no. 21, with their stated uncertainties, and are revised every year. Atmospheric lifetimes are orders of magnitude, not constants. This article describes what two institutions measure and write; it proposes no policy.
Spotted an error or an out-of-date figure? Write to us: we will correct it and re-date the article. Our texts are written with the help of artificial intelligence and checked against official sources before publication, but a figure or a definition can change without us catching it. If anything here does not match what an official body tells you, they are right.