Abstract China is the largest methane (CH 4 ) emitter globally, with the Yangtze River Delta (YRD) region recognized as a major emission hotspot. However, due to the scarcity of in situ observations and the complex spatiotemporal variability of these sources, significant uncertainties remain in regional CH 4 emission estimates. To address this, we conducted continuous atmospheric CH 4 concentration measurements from 1 June 2023, to 31 May 2024, at a central YRD site. Using an atmospheric transport model and a Bayesian inversion framework, we quantified monthly and sub‐monthly CH 4 emissions from different source categories, with a focus on waste treatment (including both landfill and wastewater). The results reveal the following key findings: (a) Substantial discrepancies were found between prior and posterior emissions across all categories. At the city scale, posterior annual CH 4 emissions were estimated to be 87.4%, 64.6%, 109.5%, and 91.9% of prior emissions for all categories, waste treatment, rice paddy + wetland, and other sources, respectively, with waste treatment contributing the largest uncertainty. (b) Strong seasonal biases were observed, with waste treatment emissions peaking in August and reaching a minimum in March (a 2.6‐fold variation), while rice paddy emissions were overestimated in May and underestimated in August by a factor of two. (c) CH 4 emissions from waste treatment exhibited high temperature sensitivity, increasing by 29%–31% per 10°C rise. Under future warming scenarios, waste treatment CH 4 emission factors (EFs) will increase by up to 121.3% under SSP5‐8.5 by the end of the century (2091–2100), relative to 2023–2024 levels. In contrast, atmospheric pressure showed negligible influence (3.2% per 1 hPa) on waste treatment CH 4 emissions. (d) More additional observations (i.e., satellite or multiple sites) are strongly suggested to resolve the prior spatial pattern of emissions, especially for fossil fuel‐related sources.
Hu et al. (Thu,) studied this question.