“In our analysis, these two effects have a similar impact. And if you put them together, you have a bigger impact,” said Yuhang Wang, a professor of atmospheric chemistry at Georgia Tech.
These two weather events seem to be getting more common, and more intense, as the climate keeps warming. This means that even as China succeeds in reducing some of its emissions, the winter haze may worsen for meteorological reasons. Really, this is what’s already happening: Even in January 2013, there was no reported massive surge in factory emissions. The sudden build-up of smog was all meteorology. “I see this as an offsetting effect,” Wang told me. “Polar, high-Arctic changes are offsetting the effort that China has been putting into emissions reductions.”
Noelle Selin, a professor of Earth and atmospheric sciences at the Massachusetts Institute of Technology, said the paper was important because it showed how local weather could shape global air pollution. “It’s a real different approach than has been traditionally taken,” she told me. Most smog research uses an atmospheric-chemistry model and not a model of the planet’s entire climate system. “And I think we definitely need both approaches.”
She added that she had pondered whether sea ice or Eurasian snow were shaping air-pollution patterns in the United States or Europe. “Being able to quantitatively test [that effect] is a really unique contribution of this paper,” she said.
Though there’s been research into how climate affects air pollution, it mostly focuses on the more developed parts of the world. Wang’s team at Georgia Tech, for instance, has found that dry, warm, autumnal air in the American southeast is leading to record-breaking ozone pollution in the region, even though industrial emissions levels are down.
Fewer studies have focused on China because its contemporary air-pollution problem is so dire. But studies like this help reveal why addressing air pollution and climate change are twin political priorities for Beijing. If air pollution is a political problem today, imagine how bad it could be when climate change intensifies it. And President Xi also has a near-term reason to figure out winter pollution: Beijing is hosting the Winter Olympics in 2022.
Speaking of low Arctic ice and smog over Beijing, Selin said she could think of few other atmospheric phenomena where such distant events were so closely correlated. The best examples, she said, were the periodic temperature swings in the oceans, like El Niño and La Niña. Yet the fact of this world is that there is always a vast and planetary dance, where silent icebergs in a cold, dark sea shape the pollution that skips across an urbane chef’s tongue.