Work done by researchers at Georgia Tech says severe winter air pollution problems in China may be worsened by changes in atmospheric circulation prompted by Arctic sea ice loss and increased Eurasian snowfall – both caused by global climate change.
According to a report on the school’s website, modeling and data analysis done at Georgia Tech suggest 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.
In the report, Yuhang Wang, a professor in Georgia Tech’s School of Earth and Atmospheric Science, says "Emissions in China have been decreasing over the last four years, but the severe winter haze is not getting better. 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 research was sponsored by the National Science Foundation and Environmental Protection Agency.
The paper is believed to be the first to link sea ice and snowfall levels to regional air pollution.
The report says haze problems in the East China Plains 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.
“The reductions in sea ice and increase in snowfall have the effect of damping the climatological pressure ridge structure over China. That flattens the temperature and pressure gradients and moves the East Asian Winter Monsoon to the east, decreasing wind speeds and creating an atmospheric circulation that makes the air in China more stagnant,” Wang says in the report.
He added, “The very rapid change in polar warming is really having a large impact on China. 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.”