Anthropogenic CO 2 Emission Reduction During the COVID-19 Pandemic: Evidence from Three Years of Urban Atmospheric Observations in Eastern China

China, the largest CO2 emitting country, implemented the strictest government control measures that restricted both outdoor activity and industrial production during the COVID-19 pandemic period, and hence, potentially reduced CO2 emissions. Large discrepancies still exist in the emission reduction rate with values ranging from ~10% to ~40% among different approaches. To our best knowledge, no study has used atmospheric CO2 observations to constrain CO2 emissions and its reduction during the COVID-19 pandemic for urban areas of China. Here, we selected Nanchang city, located in eastern China, and conducted continuous atmospheric CO2 observations from 1st January to 30th April from 2019-2021 using a 50 m tall tower. The observations were coupled with the WRF-STILT atmospheric transport model and a priori emissions using a multiplicative scaling factor and Bayesian inversion method to constrain anthropogenic CO2 emissions before, during, and after the COVID-19 pandemic. We found a 37.1%-40.2% emission reduction when compared to the COVID-19 pandemic in 2020 with the same period in 2019. Such CO2 emission reduction during the whole COVID-19 period is equivalent to planting 75%-106% of the city area with highly productive forest for a whole year. Further, emissions in 2021 were 14.3%-14.9% larger than in 2019, indicating that economic activity quickly recovered to pre-pandemic conditions. Considering China’s ambition for gradually reaching carbon emission peak by 2030 and large uncertainty for Chinese anthropogenic inventories from city to province scales, our findings can serve as an independent assessment of these CO2 hotspots for both policy makers and the carbon cycle science community.