Unveiling Seven-Decade Disparities of Methane Emissions across China

China’s century-long economic transition generated substantial methane emissions, yet the trajectory and factors of this evolution remain poorly quantified. A systematic understanding is essential for reconciling China’s economic growth with emission mitigation targets and for informing Global South nations. Using a bottom-up estimate of subnational methane emissions (1949–2022), we uncover a fundamental shift from agriculture-dominated to industry-dominated methane emissions in China. Nationwide emissions peaked in 2012, declining 3.8% by 2022, yet provincial disparities widened by 48%. While superficially reflecting heterogeneous fossil fuel use, these disparities are attributable to a shift in explanatory dominance from purely economic to dual economic-policy factors, particularly carbon policies. The long-term stability in agricultural sectors reflects nationwide efforts to food security, which maintains a baseline level of production across provinces. Recent regional decoupling masks the disproportion between emissions and economic gains. Western provinces (e.g., Shanxi, Ningxia, Guizhou) continue to exhibit high-emission but low-return economic profiles. The average of their methane emissions per GDP was 4.8 times that of eastern regions in 2022, with extremes reaching 150-fold differences. For equitable mitigation, future focus should shift from “who emits” to “why emits”, establishing a scientific basis for fair compensation between resource-dependent and resource-consuming regions.