Thick haze linked to climate change

CLIMATE change in the polar regions may have worsened winter haze problems in China, which has pledged more efforts to tackle air pollution despite the country’s decreasing emissions.

A study published in the US journal Science Advances suggests that melting Arctic Sea ice and increasing Eurasian snow – both caused by global climate change – have shifted China’s winter monsoon, helping create stagnant atmospheric conditions that trap pollution over the country’s most populous and industrial centres.

“Emissions in China have been decreasing over the last four years, but the winter haze is not getting better,” said Yuhang Wang, a professor at the Georgia Institute of Technology. “Mostly, that’s because of a rapid change in the high polar regions where sea ice is decreasing and snowfall is increasing.

“This perturbation keeps cold air from getting into the eastern parts of China where it would flush out the air pollution.”

The findings were based on an analysis of one of the worst air pollution events recorded in China, which engulfed the East China Plain in January 2013. The haze prompted the Chinese government to institute strict targets for reducing emissions.

Despite these measures, haze continues in China during the winter season. Modelling and data analysis found correlations of stagnant air conditions over China to Arctic Sea ice, which reached a record low in the autumn of 2012, and snowfall in the upper latitudes of Siberia, which reached a record high in the winter.

The results were consistent with observations that South Korea and Japan were unusually cold that winter, while East China was unusually warm, both suggesting that the cold centre had moved, Wang said. – Xinhua