Unmasking the methane myth: Why India’s cows emit far less than global estimates

Methane is a potent greenhouse gas (ghg), second only to carbon dioxide in atmospheric concentration (1.95 ppm versus 440 ppm). However, its significance is often underestimated when assessed solely on the basis of concentration, without accounting for its substantial impact on global warming. Methane is 28 times more potent than carbon dioxide in terms of global warming potential. When atmospheric concentrations are considered alongside global warming potential, it becomes clear that the effective impact of carbon dioxide is nearly eight times greater than that of methane.

Methane emissions originate from both natural and anthropogenic sources. Among anthropogenic sources, agriculture, including livestock, is a significant source of methane emissions. Agriculture as a whole accounts for around 37 per cent of global methane emissions, with enteric fermentation in ruminants serving as a significant contributor. Enteric methane emissions are an energy-inefficient yet essential process in ruminants, enabling the removal of fermentative hydrogen from the rumen. This hydrogen elimination is crucial for the optimal functioning and stability of the rumen ecosystem. Globally, livestock emit an estimated 90-100 teragrams (Tg) of methane each year through enteric fermentation.

India has often been criticised by industrialised nations for its substantial enteric methane emissions from livestock, despite the absence of reliable and context-specific emission estimates. Methane emissions from Indian livestock are largely calculated using methodologies prescribed by the Intergovernmental Panel on Climate Change (IPCC). However, discrepancies among these estimates, along with a growing body of evidence, suggested that IPCC methodologies tend to overestimate methane emissions in developing countries. This is partly because IPCC approaches rely on generalised models and emission factors applied across broad livestock categories, which may not accurately reflect regional production systems or animal performance.

The IPCC estimates are derived from any of the three-tier systems, whereby Tier I employs livestock population data by species and category, multiplied by a standard default emission factor to determine the emission estimate. Thus, the change in livestock population reflects into the change in total emission.

For a diverse country like India where the feeding practices are not uniform and substantially vary according to the seasons, regions and productive level of the livestock, applying these IPCC default Tier I values to a particular category of livestock without accounting for feed intake, diet composition, seasonal and regional variability in feed resources, and the duration of feeding leads to inaccurate and exaggerated estimates of enteric methane emissions from the livestock.

Tier II of the IPCC relies on default values obtained from the gross energy intake by the animal, the energy density of diet and the conversion efficiency of energy into methane. Since Tier II relies on default values for energy intake, density and methane conversion, any deviation in these factors results in inaccurate emission estimates. These default emission factors are primarily derived from data obtained from high-input livestock systems that involve breeds selected for optimum productivity, fed on high-energy diets, and managed under optimal conditions.

Conversely, livestock in India typically exhibits low production intensity, is often provided a less energy-dense diet and is maintained under sub-optimal to moderate management conditions; therefore, applying these default factors to our situations significantly overestimates the emission outcomes.

A recent study from China published in 2025 reported that methane emissions estimated using the IPCC Tier 2 model were overestimated by about 39 per cent. Similarly, an earlier study in 2017 confirmed that IPCC methodologies produced methane estimates for wild populations that were up to eleven times higher than actual emissions.

Recent studies conducted by the Indian Council of Agricultural Research also demonstrated that the methane emissions from the high fibre sorghum kadbi and paddy straw diets were about 34±4.9 per cent lower than the ipcc default tier II models on using the actual data on energy intake, energy density and methane conversion factor. These findings indicated that while using tier II system, we need to derive primary data on gross energy intake, diet’s energy density and conversion of feed energy into methane in different livestock species, feeding regimes varying according to the regions and seasons otherwise using default values for the above parameters yield into overestimation of methane emissions from Indian livestock.

For deriving required data, extensive animal studies are obligatory to be performed in the country where enteric methane emissions on different dietary regimes shall be quantified by employing direct measurement methods such as sulphur hexafluoride (SF6) technique, respiration chambers and Green Feed.

Data from more than 50 studies in which enteric methane emissions have been quantified using SF6 on different diets and livestock species is available in the country. This dataset may be used for developing diet-specific emission factors rather than relying on the IPCC default values.

The ICAR database on state-wise enteric methane emission revealed that Indian livestock emit about 9.25 Tg of methane per year, whereas various authors who used IPCC methodologies for the estimation of methane emission from Indian livestock have reported the annual emission up to 14 Tg.

Accurate estimation of enteric methane emissions is essential for reporting emissions across species, regions and at the national level. Moreover, the effectiveness of any methane mitigation technology cannot be properly assessed without validated and reliable measurement methodologies — underscoring the principle that we cannot reduce what we do not measure precisely. Standardised protocols for methane measurement and estimation will enable the country to track progress toward emission-reduction targets and evaluate the impact of mitigation strategies.

Developing precise methodologies will also facilitate accurate verification of methane-reduction achievements and their conversion into carbon credits, thereby providing additional monetary benefits to dairy farmers through the sale of these credits.

PK Malik is Principal Scientist and Head, Division of BE & ES, ICAR-National Institute of Animal Nutrition and Physiology, Bengaluru. Raghavendra Bhatta is Deputy Director General (Animal Sciences), Indian Council of Agricultural Research. New Delhi. Views expressed are the author’s own and don’t necessarily reflect those of Down To Earth.

This story was first published in the State of India’s Environment 2026.