A new method of hotspot analysis on the management of CO₂ and air pollutants, a case study in Guangzhou city, China

Emission inventory plays an important role in designing effective emission control strategies. Currently, there is unbalanced development of CO₂ and air pollutant emission inventories in China and the spatial information of both cannot be obtained simultaneously, which prevents a collaborative control strategy. In this study, we developed a unified emission inventory including both CO₂ and air pollutants, then utilized spatial mapping methods to identify the co-hotspots of both CO₂ and air pollutants at a high spatial resolution (1 × 1 km²). We applied Guangzhou city as a case study to illustrate the method. The results showed that CO₂ and air pollutants were mainly emitted from the stationary combustion sector and the transportation sector. These two sectors contributed 95 %, 67 %, and 93 % to total CO₂, SO₂, and NO_x emissions, respectively. Up to 86 %, 86 %, 66 %, and 72 % of total CO₂, SO₂, NO_x, and PM_2.5 emissions were attributed to the top 10 % emission grids with 1 × 1 km² resolution. However, our results showed high emission grids were not surrounded by other high emissions grids for all types of emissions analyzed in this study. The co-hotspot analysis enables accurate identification of high-emission grids, which helps environment managers to prioritize resource allocation when designing control strategies. Our study underscores the importance of managing CO₂ and air pollutants simultaneously at the city level.