## 4 Results  
### Identification of Typical Methane Emission Hotspots in China and the United States  
China leads the world in anthropogenic methane emissions and is the largest contributor to emissions from the energy sector [42; 43]. As the top coal-producing country globally, China's coal production accounted for 50.7% of the world's total coal output in 2020 [44]. Studies indicate that China's methane emissions increased by 1.1 \(\pm\) 0.4 million tons annually from 2010 to 2015, largely due to coal mining activities [45]. Changzhi, one of China's top ten coal cities, experiences significant methane leaks during underground mining and in post-mining activities where gas is harnessed for power generation. [PERSON] et al. [32] found that methane emissions from underground mining in Changzhi, Shanxi, constituted over 95% of the region's total emissions. In major fossil fuel extraction areas, there may be thousands of such emission points. The United States is the world's largest producer of oil and natural gas and has consistently been the fourth-largest emitter of methane globally since 2010, with 30% of its annual emissions originating from the oil and gas sector, particularly from shale gas extraction. In 2019, its oil and gas production accounted for 14.7% and 23.4% of the global total, respectively [46]. [PERSON] et al. [47] found that methane leaks from the U.S. oil and gas supply chain in 2015 were as high as 13 million tons, 78% more than the U.S. Environmental Protection Agency's (EPA) estimates for that year, representing a significant portion of the global oil and gas production sector's methane emissions from 2008 to 2017 (68 to 92 million tons). Crucially, methane emissions from the U.S. oil and gas industry have been increasing year by year. The Permian Basin, located in New Mexico and Texas, is currently the largest oil and gas producing region in the U.S., with rapid growth in oil and gas production over the past decade. Methane leaks during the processes of extraction, gathering, transmission, storage, and supply in this basin are substantial. A recent study by [PERSON] et al. [48] combining satellite observations from the TROPOMI on the Sentinel-5P satellite with atmospheric modeling methods revealed that the Permian Basin's methane emissions amount to 2.7 \(\pm\) 0.5 Tg CH\({}_{4}\) a-1. This figure is the largest reported methane flux from any oil and gas producing region in the U.S. to date, and is more than double the bottom-up estimates for the Permian Basin and four times higher than estimates from any other U.S. oil and gas basins. Consequently, detecting and repairing methane point source leaks in fossil fuel production activities is seen as a vital strategy for reducing greenhouse gas concentrations in the atmosphere [49]. Elucidating the dynamics of methane point source emissions from coal mines and the oil and gas production sectors in key regions is essential for bridging the gap between bottom-up and top-down methane emission estimates and for understanding how the energy sector contributes to the rapid increase in atmospheric methane concentrations. In this study, leveraging the rapid advancements in spatial imaging spectroscopy and data processing techniques, we conducted the first large-scale, high-resolution survey of methane point sources using satellite-based observations. The areas under investigation were the Changzhi region in Shanxi, China, and the Delaware sub-basin within the Permian Basin in the United States. Our dataset was acquired from two satellite missions: China's Gaofen-5 (GF5-02) equipped with the Advanced Hyperspectral Imager (AHSI) [23], and the imaging spectrometer aboard Germany's Environmental Mapping and Analysis Program (EnMAP) [26].