Projected changes in haze pollution potential in China: an ensemble of regional climate model simulations

Abstract

Abstract. Based on the dynamic downscaling by the regional climate model RegCM4 from three CMIP5 global models under the historical and the RCP4.5 simulations, this article evaluated the performance of the RegCM4 downscaling simulations on the air environment carrying capacity (AEC) and weak ventilation days (WVDs) in China, which are applied to measure haze pollution potential. Their changes during the middle and the end of the 21st century were also projected. The evaluations show that the RegCM4 downscaling simulations can generally capture the observed features of the AEC and WVD distributions over the period 1986-2005. The projections indicate that the annual AEC tends to decrease and the annual WVDs tend to increase over almost the whole country except central China, concurrent with greater change by the late 21st century than by the middle of the 21st century. It suggests that annual haze pollution potential would be enlarged under the RCP4.5 scenario compared to the present. For seasonal change in the four main economic zones of China, it is projected consistently that there would be a higher probability of haze pollution risk over the Beijing-Tianjin-Hebei (BTH) region and the Yangtze River Delta (YRD) region in winter and over the Pearl River Delta (PRD) region in spring and summer in the context of the warming scenario. Over Northeast China (NEC), future climate change might reduce the AEC or increase the WVDs throughout the whole year, which favours the occurrence of haze pollution and thus the haze pollution risk would be aggravated. The relative contribution of different components related to the AEC change further indicates that changes in the boundary layer depth and the wind speed play leading roles in the AEC change over the BTH and NEC regions. In addition to those two factors, the precipitation change also exerts important impacts on the AEC change over the YRD and PRD zones.

Future changes in Beijing haze events under different anthropogenic aerosol emission scenarios

“…If there is no change in aerosol emission in future, increased stagnation days and decreased light precipitation days associated with global warming would also cause an increase in air pollution days in eastern China (Chen et al, 2019). Regional climate model simulations under the RCP4.5 scenario showed that the air environment carrying capacity, a combined metric measuring the capacity of the atmosphere to transport and dilute pollutants, tends to decrease in the 21 st century across China (Han et al, 2017).…”

Projected changes in autumn rainfall over West China: Results from an ensemble of dynamical downscaling simulations

“…Following the international Coordinated Regional Climate Downscaling Experiment (CORDEX)-East Asia phase II (Giorgi et al, 2009), the region for the downscaling simulations covers the whole China and the adjacent areas (Figure 1 (a)). The physical parameterization schemes employed are the same as that described in the studies of Gao et al (2016Gao et al ( , 2017 and Han et al (2017).…”

Is reducing new particle formation a plausible solution to mitigate particulate air pollution in Beijing and other Chinese megacities?

“…The local meteorological conditions found to be associated with haze formation in Beijing include low wind speeds, high humidity content of air and low intensity of solar radiation 18,[23][24][25] . Climate warming arguably influences weather conditions in such a way that the likelihood of winter haze episodes in Beijing has already increased, and is likely to increase further in the future 12,[26][27][28][29] .…”