Structural changes and impacts of methane emissions in China.

The annual increase in total methane emissions in China has decelerated, largely due to the continued implementation of effective emission reduction policies. Tracking methane emission hotspots and characterizing their emission profiles are critical for driving further reductions. However, the specific role of strong methane emissions in the annual trend changes of China's methane emissions, as well as seasonal emission profiles, has not been clarified. In this study, we use TROPOMI satellite observations to estimate methane emissions in China for 2019-2023 and comprehensively analyze the driving mechanisms of the trend changes and seasonal variations of methane emissions in China by combining the emissions structural properties with the emission regions' signatures. Our results reveal that methane emission trends in China over the five years, based on top-down estimations, have significantly moderated. Emission intensity has declined, stability has improved, and the geographic distribution exhibits a pronounced north-heavy and south-light pattern. While the proportion of unstable strong emissions has remained small and consistent over the years, their contribution to total emissions remains significant. Moreover, the influence of stable strong emissions and unstable weak emissions on overall methane levels has grown over time. Unstable strong emissions, primarily linked to energy-related activities, play a pivotal role in shaping seasonal methane emission trends in China. These findings highlight the complex interplay of emission sources and provide valuable insights for refining methane reduction strategies.