Government environmental control measures on CO2 emission during the 2014 Youth Olympic Games in Nanjing: Perspectives from a top-down approach

Strict air pollution control measures were conducted during the Youth Olympic Games (YOG) period at Nanjing city and surrounding areas in August 2014. This event provides a unique chance to evaluate the effect of government control measures on regional atmospheric pollution and greenhouse gas emissions. Many previous studies have observed significant reductions of atmospheric pollution species and improvement in air quality, while no study has quantified its synergism on anthropogenic CO₂ emissions, which can be co-reduced with air pollutants. To better understand to what extent these pollution control measures have reduced anthropogenic CO₂ emissions, we conducted atmospheric CO₂ measurements at the suburban site in Nanjing city from 1^st July to 30^th September 2014 and 1^st August to 31^st August 2015, obvious decrease in atmospheric CO₂ was observed between YOG and the rest period. By coupling the a priori emission inventory with atmospheric transport model, we applied the scale factor Bayesian inversion approach to derive the posteriori CO₂ emissions in YOG period and regular period. Results indicate CO₂ emissions from power industry decreased by 45%, and other categories also decreased by 16% for manufacturing combusting, and 37% for non-metallic mineral production. Monthly total anthropogenic CO₂ emissions were 9.8 (±3.6) × 10⁹ kg/month CO₂ for regular period and decreased to 6.2 (±1.9) × 10⁹ kg/month during the YOG period in Nanjing city, with a 36.7% reduction. When scaling up to whole Jiangsu Province, anthropogenic CO₂ emissions were 7.1 (±2.4) × 10¹⁰ kg/month CO₂ for regular period and decreased to 4.4 (±1.2) × 10¹⁰ kg/month CO₂ during the YOG period, yielding a 38.0% reduction.