Support Carbon Neutral Goal with a High-Resolution Carbon Monitoring System in Beijing

Abstract China has committed to peak its carbon emissions before 2030 and achieve carbon neutrality before 2060, known as the dual carbon goals (DCGs). To support the DCG, monitoring and assessment of progresses in emissions reduction have become a central research focus. Here, we describe the Beijing–Tianjin–Hebei (JJJ) carbon monitoring system, established over the last 6 years through a collaborative effort of 16 research institutions and universities. The monitoring capability includes ground-based high-precision reference stations, a dense network of medium-accuracy low-cost sensors, carbon satellites, vertical profile samplers, and mobile platforms. Observations using the network have shown CO 2 variations from diurnal-, synoptic- to seasonal-interannual time scales, as well as dramatic on-road changes during the COVID-19 lockdown. High-resolution modeling and data assimilation at kilometer scale reveal major deficiencies in global carbon emission datasets at regional/city scale. The inversion found the total fossil fuel CO 2 emissions of the City of Beijing to be 117 megatonne (Mt) but much lower than the national-databased inventories (152 MtCO 2 ). The results have been used in emission assessment by national and local environmental protection agencies. Similar systems are now being developed in other Chinese cities. Significance Statement China’s carbon neutral goal by 2060 requires our ability to monitor and assess progresses in its path to decarbonization with unprecedented resolution at city and regional scale where most of the CO 2 emissions occur. Since 2017, a collaborative effort from 16 research institutions has built a carbon monitoring system for the Beijing–Tianjin–Hebei (JJJ) city cluster. Data from a network of ground-, air-, and space-based observations showed CO 2 variations at diurnal-, synoptic- to seasonal-interannual time scales, as well as dramatic on-road changes during the COVID-19 lockdown. High-resolution modeling and data assimilation at kilometer scale reveal major deficiencies in global carbon emission datasets. The results are being used in emission assessment by national and local environmental protection agencies, adopted at other Chinese cities.