It could take more than twenty years for the air in the most polluted cities in China to reach acceptable levels, according to research published in the Journal of Geophysical Research: Atmospheres.
With rapid industrialization and urbanization over the past decades, China has experienced widespread air pollution induced by fine particulate matter with a diameter of 2.5 µm or less (PM2.5). To protect human health and meet the newly implemented annual PM2.5 target (less than 35 µg m-3), great efforts are needed to reduce emissions effectively. It is therefore essential to understand how future PM2.5 concentrations are affected by changes in anthropogenic emissions.
An aerial view of a real-time image of Beijing Olympic Park Zone taken by HD cameras.(Credit:Institute of Atmospheric Physics, Chinese Academy of Sciences, http://view.iap.ac.cn:8080/imageview/)
Using global chemical transport and future emission scenarios, a team of researchers from the Chinese Academy of Sciences' Institute of Atmospheric Physics constructed four representative concentration pathways (RCPs) scenarios: RCP2.6, RCP4.5, RCP6.0 and RCP8.5. On the basis of the four RCPs, they projected PM2.5 concentrations expected in 2030 in four regions of China: Beijing-Tianjin-Hebei, Yangtze River Delta, Pearl River Delta and the Sichuan Basin.
"In consideration of annual PM2.5 target, controlling PM2.5 pollution in Beijing-Tianjin-Hebei and the Sichuan Basin will be challenging,” said Professor Liao Hong, corresponding author of the study. “In these two regions, it will take at least two decades to achieve the annual PM2.5 target under the RCP2.6, RCP4.5, and RCP8.5 scenarios, and PM2.5 concentrations will keep increasing under RCP6.0."
The researchers also predicted that by 2050, aerosols would increase warming through radiative forcing, suggesting that policymakers should consider the impacts of aerosol concentrations.
"There is a long way to go to mitigate future PM2.5 pollution in China based on the emission scenarios,” said Liao. “At the same time, the consequent warming from reduced aerosols is also significant and inevitable."