Methane

Geography glossary

Also called: CH4 · Topic: Climate Change: Causes, Evidence and the Global Response · NCERT: Class 11, Ch 11 "World Climate and Climate Change"

Meaning

Methane (CH4) is a strong greenhouse gas (a gas that traps the Earth's outgoing heat). It is the main part of natural gas, and microbes also make it when they break down plant and animal matter without oxygen. Methane causes about 16% of the warming from long-lived greenhouse gases, second only to carbon dioxide (CO2) [3]. It stays in the air for only about 12 years, so cutting it is one of the fastest ways to slow warming.

Explanation

How methane forms and traps heat

  • How it forms:
  • Microbes break down organic matter (dead plants, animal waste, food) in places with no oxygen: under floodwater, inside a cow's stomach, or deep in a rubbish heap.

  • This produces methane, which escapes into the air.

  • How it warms the Earth:

  • The ground absorbs sunlight and sends heat back out as longwave (infrared) radiation.
  • Methane absorbs part of this outgoing heat and sends some of it back down.

  • The lower air and the surface become warmer. This is the greenhouse effect.

  • Methane occurs in nature, so it is part of the natural greenhouse effect too. Extra methane from human activity adds to the enhanced greenhouse effect, which causes global warming.

Why a small amount matters so much

  • Global warming potential (GWP) compares how much heat 1 kg of a gas traps over 100 years with 1 kg of CO2 (CO2 = 1).
  • Methane's GWP is about 28. So 1 kg of methane traps about 28 times as much heat as 1 kg of CO2 over a century.
  • Lifetime: about 12 years. WMO gives about 9 years [3]. CO2, by comparison, stays for centuries (part of it).
  • What this means for policy:
  • Methane does not stay in the air for long.
  • So if emissions are cut, its level falls within a few years.
  • That is why cutting methane slows warming quickly.

How much there is now

  • Level in 2024: 1,942 ppb (parts per billion), which is 166% above the pre-industrial level [3].
  • Put simply, methane has risen over 160% since 1750. That is a much bigger rise than CO2's (about 280 ppm before the Industrial Revolution, 423.9 ppm in 2024 [3]).
  • Radiative forcing is the extra heat energy a gas traps per square metre of the Earth's surface. Methane's radiative forcing in 2024 was 0.57 W/m², or 16% of the total from long-lived gases [2].

Main sources

  • Human sources:
  • Flooded paddy fields: standing water cuts off oxygen from the soil, so microbes make methane.
  • Livestock: cows and buffaloes release methane while digesting food.
  • Landfills: buried waste rots without oxygen.
  • Coal mines: methane trapped in coal seams escapes.

  • Leaks from oil and gas systems: a fast-growing human source.

  • Natural source: wetlands (marshes and swamps).

Where it occurs

  • India:
  • Paddy fields in West Bengal, Uttar Pradesh, Punjab and Odisha are a major source.
  • Livestock: India has the world's largest cattle population.

  • Landfills near cities and coal mines add more.

  • World:

  • Wetlands are the main natural source.

  • Oil and gas systems leak methane wherever natural gas is produced and transported.

  • Global Methane Pledge:

  • It was launched at COP26 (Glasgow, 2021).
  • Its members aim to cut methane emissions by 30% from 2020 levels by 2030.
  • India has not joined. Its methane comes mostly from paddy farming and livestock, which support small farmers. India calls these survival emissions, not luxury emissions.

Don't confuse with

  • Carbon dioxide (CO2): CO2 has a GWP of 1 and part of it lasts for centuries, but it causes the largest share of warming (66%) [2]. Methane is stronger per kg (GWP ~28) and short-lived (~12 years), and it causes a smaller share (16%) [2].
  • Nitrous oxide (N2O): this gas also comes from farming, but from nitrogen fertilisers and manure, not from flooded paddy or digestion. It lasts over 100 years, has a GWP of about 270, and it also destroys ozone. Methane does not.
  • Water vapour: it is the largest natural greenhouse gas, but it is a feedback, not a driver, because it stays in the air for only days. Methane is a driver that humans add directly.
  • Survival emissions vs luxury emissions: India's methane from paddy and livestock feeds people and supports livelihoods (survival). Emissions from high-consumption lifestyles are luxury emissions. This difference explains why India is not in the Global Methane Pledge.

Prelims Hooks

  • Lowest to highest GWP (100 yr): CO2 (1) < methane (~28) < nitrous oxide (~270) < CFCs (thousands).
  • Share of long-lived GHG radiative forcing, 2024: CO2 66% > methane 16% > CFCs ~8% > N2O ~6% [2].
  • Methane in 2024: 1,942 ppb, 166% above the pre-industrial level [3].
  • Lifetime: about 12 years (WMO: about 9 years [3]). Trap: methane is short-lived but strong. It is not the longest-lasting greenhouse gas.
  • Global Methane Pledge: COP26, Glasgow, 2021. A 30% cut by 2030 from 2020 levels. India is not a member.
  • NCERT (Class 11) lists CO2, CFCs, methane, nitrous oxide and ozone as the main greenhouse gases.

Mains Points

  • Farming is a key driver of the enhanced greenhouse effect (GS-I/III):
  • Flooded paddy and India's huge cattle population release methane. Landfills, coal mines and gas leaks add more.

  • Methane is now 166% above the pre-industrial level [3]. Because it lasts only about 12 years, cutting it gives the quickest climate benefit.

  • India's position (GS-III environment):

  • India stays out of the Global Methane Pledge to protect farm livelihoods and food security. It treats farm methane as survival emissions.

  • At the same time, India joined the Kigali Amendment, which is an industrial phase-down backed by technology [4]. This shows India picks commitments that do not hurt poor farmers.

  • Ways to cut methane without hurting farmers:

  • In paddy: direct-seeded rice (sowing seeds straight into the field instead of transplanting seedlings into flooded plots) and alternate wetting and drying (letting the field dry out between irrigations, so less methane forms).
  • In livestock: better cattle feed.
  • In waste: biogas under GOBAR-Dhan, which turns dung and waste into fuel.

Related concepts

Read more

Sources

  1. 1Class 11, Ch 11 "World Climate and Climate Change" (primary)
  2. 2NOAA Global Monitoring Laboratory — Annual Greenhouse Gas Index (AGGI)gml.noaa.gov · tier 2
  3. 3WMO — Carbon dioxide levels increase by record amount to new highs in 2024wmo.int · tier 2
  4. 4PIB — Cabinet approves Ratification of Kigali Amendment to the Montreal Protocol for phase down of Hydrofluorocarbonspib.gov.in · tier 1