India's methane emissions lower than global inventory estimates; better monitoring needed: Study

Methane emissions over India are lower than what is reported in some widely used global emission inventories, according to a study, stressing the need for a stronger monitoring network. Methane is one of the most powerful greenhouse gases driving global climate change. While it remains in the atmosphere for a shorter time than carbon dioxide, it heats the atmosphere far more effectively. This makes methane a prime low-hanging fruit for immediate action to combat warming and reduce climate risks in the coming decades. In India, a rapidly developing economy where agriculture, waste management, and energy production are significant sources of methane emissions, there is an urgent need for improved estimates and effective controls on these gases. Addressing this is essential to significantly reduce both economic and environmental burdens, said Indian Institute of Science Education and Research (IISER), Bhopal, Associate Professor Dhanyalekshmi Pillai. She, along with Thara Anna Mathew and Jithin S Kumar from IISER Bhopal, and other national and international scientists, conducted an examination of India's methane emissions for 2018-201, recently published in the European Geosciences Union's Atmopsheric Chemistry and Physics Journal. ''Strikingly, the study suggests that methane emissions over India are lower than the activity-based statistical estimates reported in some widely used global emission inventories,'' Pillai said. ''That is a wake-up call: better measurements can significantly reshape our understanding of where the country stands,'' she added. By advancing measurement and modelling techniques, the study finds that India annually emits between 21.9 and 24.9 teragrams of methane into the atmosphere. At the same time, the improved estimates are about 19 per cent higher than those reported in India's Fourth Biennial Update Report, which places methane emissions at 19.6 teragrams per year. In other words, India appears to emit less methane than global databases claim, but more than the national report suggests, Pillai said. ''This is why India urgently needs a far stronger methane monitoring network,'' she said. Better monitoring improves emission estimates, strengthens validation, and reveals regional and seasonal patterns that estimation systems can easily miss, the study said. In a country as vast and varied as India, these hidden patterns could make the difference between broad assumptions and truly targeted climate action, Pillai said. ''When credible measurements are paired with innovative technology and advanced analytical tools, they can identify hotspots, inform smarter policy, and accelerate more effective methane mitigation. With this, the country can focus on climate security, economic stability, and on building a future that is more sustainable, resilient, and environmentally just,'' she added. The study by scientists has an advanced approach integrating satellite-based methane observations, ground-based atmospheric measurements, and atmospheric transport modelling. Using cutting-edge technology, these scientists brought together millions of precise satellite measurements with sophisticated physics models to move beyond traditional activity-based accounting and build a clearer, more detailed, and credible picture of India's methane budget, Pillai said. The team of scientists utilised observations from TROPOMI, the TROPOspheric Monitoring Instrument on board the European Space Agency's Sentinel-5P satellite. TROPOMI measures the spectral absorption of light corresponding to methane molecules in the air. Then they used complex radiative transfer models across the atmospheric fine levels to convert spectral signatures into retrievals of methane, representing the dry-air column-averaged methane concentration from the surface to the top of the atmosphere. With the daily global coverage of measurements, the novel technique helps monitor methane levels across various environments, including agricultural, urban, industrial, wetland, and coastal regions, Pillai said.