Why in news?
A global study found that rice-paddy emissions roughly doubled over six decades. Expansion of cultivated area was the largest driver. Greater crop-residue incorporation was the next major driver. Irrigated rice regions in India remain important methane hotspots.
Background
Methane is the simplest hydrocarbon, containing one carbon atom and four hydrogen atoms.
Its chemical formula is CH4, and the gas is colourless, odourless and highly flammable.
Commercial fuel gas receives an added smell for leak detection because pure methane has none.
Methane is the main natural-gas component and also forms during oxygen-free organic decomposition.
Wetlands are the largest natural source, while human sources include agriculture, fossil fuels, landfills and wastewater.
Why is methane a powerful greenhouse gas?
Greenhouse gases absorb heat leaving Earth's surface and return some towards the lower atmosphere.
Methane remains for about a decade, while carbon dioxide can influence climate much longer.
A methane emission traps much more heat initially, although its comparison depends upon the chosen period.
Over 20 years, methane warms about 80 times more than equal-mass carbon dioxide.
Over 100 years, the commonly used estimate is roughly 27 to 30 times.
Methane is responsible for approximately one-third of current global warming.
Time horizon matters: Methane's warming value appears larger over 20 years because it is powerful but short-lived.
Why do flooded rice fields produce methane?
- Standing water blocks rapid oxygen movement into the paddy soil.
- Soil microbes soon consume much of the available oxygen.
- Methanogenic microorganisms then break down organic material without oxygen.
- This process releases methane within the waterlogged soil.
- Methane escapes through bubbles, water and air channels inside rice plants.
Methanogens belong to a microorganism group called archaea, which differs from ordinary bacteria.
Straw, roots and manure supply carbon, so incorporating excessive residue can increase methane production.
What did the new study examine?
The study appeared in the journal Nature Food during 2026.
Researchers combined three methods: a data model, an ecosystem model and a field-study analysis.
The field analysis covered over 1,255 sites, while independent methods tested whether broad patterns remained consistent.
Net rice-paddy greenhouse emissions roughly doubled between the study's 1961โ1980 and 2001โ2020 periods.
Soil carbon dioxide emissions rose 52 per cent, while methane emissions rose 44 per cent.
How large were recent emissions?
During the 2010s, global paddies emitted about 1,090 teragrams of carbon-dioxide equivalent yearly.
The uncertainty was 350 teragrams in either direction, and one teragram equals one million tonnes.
The central estimate therefore equals about 1.09 billion tonnes yearly.
Carbon-dioxide equivalent compares gases through warming effects; it does not mean every emission was carbon dioxide.
Reading the number: The 1.09-billion-tonne figure combines several gases using their estimated warming effects.
What drove the historical increase?
- Expansion of global rice area contributed more than any other factor.
- More intensive crop-residue incorporation provided extra material for decomposition.
- East Asian methane increases were linked with excessive straw incorporation.
- Africa became an emerging hotspot as paddy cultivation expanded rapidly.
- Indian irrigated rice zones remained among the important global source regions.
Every rice field emits differently because water, soil, climate and farming practices vary.
How can farmers reduce emissions?
Alternate wetting and drying: Fields dry to a safe level before being irrigated again.
This method interrupts oxygen-free conditions and can reduce methane, but needs dependable water control.
Direct-seeded rice: Seed is planted directly instead of transplanting seedlings into continuously puddled fields.
The method can save water and labour where conditions suit it, although weed management becomes crucial.
Residue management: Farmers can avoid incorporating excessive fresh straw immediately before flooding.
Composting, removal for useful products or earlier incorporation may reduce peak methane production.
Balanced inputs: Appropriate nitrogen, tillage and organic additions can reduce avoidable emissions.
Suitable varieties: Breeding can target strong yields with lower methane movement or production.
Can mitigation create trade-offs?
Yes. Poorly timed field drying can stress rice and reduce yield.
Extra oxygen may increase nitrous oxide, which is another powerful greenhouse gas.
Water-saving methods may fail under poor drainage, so advice must match local soils and irrigation systems.
The study estimated that improved practices could cut future net emissions by about 10 per cent.
The model avoided yield loss, but real implementation still requires local testing and farmer support.
Why does this matter for India?
Rice provides food and income for millions, so climate policy cannot ignore production needs or farmer security.
The goal is lower emissions per food unit, while water-saving measures can improve drought resilience.
Reliable field measurements are essential because national averages hide local differences.
Conclusion
India can reduce rice methane through better water and residue management without treating food production as the problem.