Rebecca Morelle BBC News 14 Apr 14;
Air pollution in China and other Asian countries is having far-reaching impacts on weather patterns across the Northern Hemisphere, a study suggests.
Researchers have found that pollutants are strengthening storms above the Pacific Ocean, which feeds into weather systems in other parts of the world.
The effect was most pronounced during the winter.
The study is published in the Proceedings of the National Academy of Sciences (PNAS).
Lead author Yuan Wang, from the Jet Propulsion Laboratory at the California Institute of Technology, said: "The effects are quite dramatic. The pollution results in thicker and taller clouds and heavier precipitation."
Toxic atmosphere
Parts of Asia have some of the highest levels of air pollution in the world.
In China's capital, Beijing, pollutants frequently reach hazardous levels, while emissions in the Indian capital, Delhi, also regularly soar above those recommended by the World Health Organization.
This has dire consequences for the health of those living in these regions, but there is growing evidence that there are other impacts further afield.
To analyse this, researchers from the US and China used computer models to look at the effect of Asia's pollution on weather systems.
The team said that tiny polluting particles were blown towards the north Pacific where they interacted with water droplets in the air.
This, the researchers said, caused clouds to grow denser, resulting in more intense storms above the ocean.
Dr Yuan Wang said: "Since the Pacific storm track is an important component in the global general circulation, the impacts of Asian pollution on the storm track tend to affect the weather patterns of other parts of the world during the wintertime, especially a downstream region [of the track] like North America."
Commenting on the study, Professor Ellie Highwood, a climate physicist at the University of Reading, said: "We are becoming increasingly aware that pollution in the atmosphere can have an impact both locally - wherever it is sitting over regions - and it can a remote impact in other parts of the world. This is a good example of that.
"There have also been suggestions that aerosols over the North Atlantic effect storms over the North Atlantic, and that aerosols in the monsoon region over South Asia can affect circulation around the whole of the world."
Asian Pollution Boosts Pacific Storm Power
Becky Oskin, LiveScience.com Yahoo News 15 Apr 14;
Pollution from China's coal-burning power plants is pumping up winter storms over the northwest Pacific Ocean and changing North America's weather, a new study finds.
Northwest Pacific winter storms are now 10 percent stronger than they were 30 years ago, before Asian countries began their industrial boom, according to research published today (April 14) in the Proceedings of the National Academy of Sciences.
North America will be hardest hit by the intensifying storms, which move from west to east, said lead study author Yuan Wang, an atmospheric scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif.
"The increasing pollution in Asian countries is not just a local problem, it can affect other parts of the world," Wang told Live Science.
Aerosol emissions have rapidly increased in Asia in recent decades. For example, China is now the world's largest coal consumer, and in Beijing, air pollution levels have soared 400 times higher than World Health Organization limits. In contrast, aerosols from North America and Europe have meanwhile decreased, because of clean air regulations. [China's Top 6 Environmental Concerns]
Wang and his co-authors examined how the tiny pollution particles in Asia play a role in cloud formation and the storms that spin up each winter east of Japan, in a cyclone breeding ground north of 30 degrees latitude. Monsoon winds carry aerosols from Asia to this storm nursery in the winter.
The researchers created a computer model of six kinds of aerosol pollution and tested their effects on clouds, precipitation and global weather patterns. Different aerosols affect storms in varying ways, such as by blocking the sun's radiation or providing a nucleus around which water vapor can condense to form raindrops.
The new study finds that sulfate aerosols are among the most important drivers of Pacific storms, by encouraging more moisture to condense in clouds, Wang said.
Pollution from Asia is also changing weather patterns over North America, Wang added.
Wang said this winter's unusually cold weather east of the Rocky Mountains could have been influenced by pollution-driven cyclones and high-pressure systems in the northern Pacific. These Pacific weather patterns caused swoops in the jet stream that drove cold air south across the central and eastern United States — the so-called polar vortex. The same weather patterns are linked with record-high temperatures in Alaska this winter.
"This cold winter in the U.S. probably had something to do with stronger cyclones over the Pacific," Wang said.
The researchers are testing more sophisticated computer models to better understand the effects of stronger storms and increasing pollution on global weather patterns, Wang said.
