Global Warming Increases the Incidence of Haze Days in China

Abstract

Both wind strength and anthropogenic emissions have been assumed to be the dominant factors in determining the occurrence of hazy weather in China. However, few records are available with sufficient temporal length and resolution, which enable the two signals to be separated, and hence address the dynamics of haze days and the global impact of the anthropogenic emissions in China, particularly in the context of global warming. Here we present the first long‐term (last ~180 years) lake sediment records of changes in wind strength and atmospheric loading of anthropogenic emissions in China. Our results show that the atmospheric loading of anthropogenic emissions and haze formation are closely related to the changes in wind strength associated with temperature changes, which are likely forced by tropical sea surface temperature. Comparison of our results with Pb isotope records from Japan and with the record of Pb concentrations in Greenland ice core indicates that the anthropogenic pollutants emitted in China stagnate mainly over the source area and neighboring regions, which thus favors haze formation under a warming climate. However, they would be transported worldwide under conditions of strong winds and decreased temperature. Climatic warming, together with the periodic changes in temperature, has caused unprecedented heavy haze days in recent decades in China. The observed pattern of periodic temperature variations suggests that in the next ~30 years, wind strength will increase and thus reduce the incidence of haze days. However, this reduction may be attenuated by continued climatic warming as anthropogenic greenhouse gases emissions continue.

Uneven Warming Likely Contributed to Declining Near‐Surface Wind Speeds in Northern China Between 1961 and 2016

“…Declining near‐surface wind speed trends were simulated in CAM5‐Nat for annual averages and for some seasons, which indicates that the natural variability also plays a role in regulating the variation of near‐surface wind speed in northern China. This is confirmed by a periodic change in wind activity over northern China from ∼1850 to ∼1950 (Xu et al., 2019), that is, over a period with relatively low anthropogenic emissions of greenhouse gases and aerosols compared to 1960–2016. Note that differences in wind speed evolution among seasons were not fully related to the differences of the air temperature and pressure gradients, which means that other physical processes also affected wind speed.…”

Contribution of climate/meteorology to winter haze pollution in the Fenwei Plain, China

“…Table 2 shows that these climate factors could be divided into five major categories: the H500 anomaly in the Northern Hemisphere, SLP oscillation, SST, sea ice anomaly, and global warming. For example, with GT increases in recent decades, changes in wind strength associated with temperature changes would lead to the accumulation of anthropogenic pollutants, causing unprecedented heavy haze pollution in China (Xu et al ., 2019). In Beijing, 1.5°C (2°C) global warming is expected to increase the frequency of severe haze events by 21% (18%) (Qiu et al ., 2020).…”

Effect of rainfall-induced diabatic heating over southern China on the formation of wintertime haze on the North China Plain

“…Unfortunately, continued global warming will further increase the incidence of haze days in China by reducing the wind strength (Cai et al, 2017;Xu et al, 2019). Callahan and Mankin (2020) found that climate change will lead to hazefavorable conditions over Beijing becoming more frequent, but that internal variability can generate large uncertainties in these projections.…”