Estimation of Anthropogenic CH₄ and CO₂ Emissions in Taiyuan‐Jinzhong Region: One of the World's Largest Emission Hotspots

Abstract

Coal mining ranks as the largest anthropogenic CH 4 source in China with emission factors (EFs) varying up to 30-fold among inventories when applied to different provinces. The lack of independent evaluation of coal mining CH 4 EFs in China is one of the main uncertainties in estimating national total CH 4 emissions. Shanxi province, which supplies 25% of the national coal production, is the largest coal mining CH 4 emission region in China and even among the world's largest coal production regions. This area is also a significant anthropogenic CO 2 source because of high-density power and industrial activities. Given the large uncertainties in CH 4 and CO 2 inventories from provincial to city scales, questions remain whether state-of-theart inventories have accurately estimated these emission hotspots. Here, we evaluate CH 4 and CO 2 emissions from one of the world's largest coal production regions near Taiyuan City, the capital of Shanxi province, China. CH 4 and CO 2 concentrations were measured from March 2018 to February 2019 from a 30-m tower. These data were used within an inverse modeling framework to simulate both CH 4 and CO 2 concentrations and to evaluate EFs for this region. Results show generally good agreement between observed and simulated CH 4 concentrations. However, the CO 2 simulations were much lower compared to the observations. Given the minor role of NEE-induced CO 2 enhancements, we believe that the large difference is attributed to the underestimation of anthropogenic CO 2 emissions. In general, the derived posteriori anthropogenic CH 4 emissions were 85.2(±18.1)% of a priori emissions, where fugitive CH 4 from coal mining accounted for ∼92.7% of total anthropogenic emissions. The derived coal mining EF was 23.2(±4.9) m 3 CH 4 /ton coal, close to the default value of high CH 4 -content coal, but twofold the province average that were reported by previous observation-based studies in Shanxi province, indicating large spatial inhomogeneity in the coal mining CH 4 EF. The posteriori CO 2 emissions were 1.6-fold of the a priori emissions, highlighting underestimation of CO 2 emissions in industrial cities and some potential large emission sources that are missing from state-of-the-art inventories. Finally, we also emphasize the use of satellite observations and denser tower-based networks are essential in resolving the spatial inhomogeneity of greenhouse gas emissions. Plain Language SummaryThe understanding of anthropogenic CH 4 and CO 2 emissions is basis for climate mitigation especially for global top emitting countries, but the largest issue before addressing above question is that many previous studies have found considerable bias of greenhouse gas emission for almost all inventories from city to regional scales. These facts hindered the government to make and evaluate corresponding mitigation policies. Here, to quantify CH 4 and CO 2 emissions at one of global largest CH 4 and CO 2 hotspot in China, we conducted 1 year tower-based atmospheric CH 4 and CO 2 concentration measurements a...