Evaluating national, state, and urban Indian methane emissions using satellites

Abstract. Understanding the spatial distribution and magnitude of methane emissions is critical for developing effective mitigation strategies, particularly in rapidly growing economies like India, the world’s most populous country and a top global methane emitter with diverse emission sources. We quantify India’s 2021 methane emissions at up to 0.25°×0.3125° resolution using TROPOspheric Monitoring Instrument (TROPOMI) observations in a Bayesian inversion with the Integrated Methane Inversion framework (IMI). Prior emissions come from state-of-the-art global gridded bottom-up inventories and incorporate GHGSat-based estimates for eighteen landfills. The high-resolution inversion and incorporation of GHGSat data enable us to evaluate and interpret results at multiple policy-relevant scales. The national posterior emission estimate is 34.4 (32.0 – 40.4) Tg/yr, of which 31.5 (29.6 – 36.7) Tg yr^-1 is anthropogenic, consistent with bottom-up prior emissions but 68 % higher than India’s UNFCCC inventory. National landfill and oil & gas emissions are 30 % higher, while coal emissions are 57 % lower than prior estimates. State-level analysis highlights seven states with higher emissions, with notably higher oil and gas emissions in Assam and Gujarat, and lower coal mining emissions in Rajasthan and Odisha. Urban-scale posterior estimates for fourteen cities reveal significant differences from the prior in ten cities. Posterior wastewater emissions are higher in nine cities, with the largest increases in Kolkata and Delhi, consistent 60–90 % of their populations lacking access to wastewater treatment facilities. GHGSat observations reveal landfills contribute 10–38 % of emissions in eleven cities, emphasizing the critical role of solid waste management. These results illustrate how satellite-based analyses can inform methane mitigation.