China’s severe winter haze tied to effects of global climate change

China's severe winter haze tied to effects of global climate change

China’s severe winter air pollution problems may be worsened by changes in atmospheric circulation prompted by Arctic sea ice loss and increased Eurasian snowfall – both caused by global climate change.

Modeling and data analysis done by researchers at the Georgia Institute of Technology suggest that sea ice and snowfall changes have shifted China’s winter monsoon, helping create stagnant atmospheric conditions that trap pollution over the country’s major population and industrial centers.

Those changes in regional atmospheric conditions are frustrating efforts to address pollution through emission controls.

“Emissions in China have been decreasing over the last four years, but the severe winter haze is not getting better,” said Yuhang Wang, a professor in Georgia Tech’s School of Earth and Atmospheric Sciences.

“Mostly, that’s because of a very 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 paper presents a clear example of how large-scale perturbations caused by global climate change can have significant regional impacts, and is believed to be the first to link sea ice and snowfall levels to regional air pollution.

Haze problems in the East China Plains – which include the capital Beijing – first gained worldwide attention during the winter of 2013 when an instrument at the U.S. embassy recorded extremely high levels of PM 2.5 particles. The haze prompted the Chinese government to institute strict targets for reducing emissions from industry and other sources.

Though these emission controls appear to be working, the haze during December and January continues. So Wang and colleagues Yufei Zou, Yuzhong Zhang and Ja-Ho Koo wondered if other factors may be playing a role.

“Despite the efforts to reduce emissions, we think that haze will probably continue for the future,” he said. “This is partly climate-driven now, so it probably won’t get much better in the winter. Emissions are no longer the only driver of these conditions.”

Wang hopes to continue the study using new data from China’s air quality monitoring network.

The impact of global climate change, he said, may be unique to China because of its geography and sensitivity to changes in atmospheric circulation structure. Though the problem is now manifested in air pollution, he said the results of the study should encourage the nation to continue addressing climate change.

“The very rapid change in polar warming is really having a large impact on China,” he said. “That gives China an incentive to not only follow through on air pollutant emission reductions, and also to look at the potential for reducing greenhouse gas emissions. Our research shows that cutting greenhouse gases would help with the winter haze problem.”

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News source: Georgia Institute of Technology. The content is edited for length and style purposes.
Figure legend: This Knowridge.com image is credited to Yuhang Wang.