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Asian Pollution Affects Weather Over Pacific

Severely polluted air has become the norm in many Asian cities today. With the rapid growth and industrialization of Asia's economy, fossil fuel emissions from factories, power plants and automobile tailpipes are spewing into the atmosphere. Scientists believe this concentrated pollution has the potential to change weather patterns far beyond Asia.

Texas A&M atmospheric scientist Renyi Zhang studies tiny airborne particles known as aerosols that are suspended in the clouds. Some of these tiny particles, such as sea salt, are natural, but others, such as soot and sulfates, are produced when coal is burned.

Zhang says his research is the first to link Asian air pollution and changing Pacific weather patterns. He says the abundance of aerosol pollutants changes how clouds are formed. "Over the last decade the amount of deep convective clouds has increased from somewhere between 20 and 50 percent."

These dense high-altitude clouds can be many kilometers thick and lead to more intense storms over the Pacific. The findings, says Zhang, are based on satellite measurements from 1984 to 2005 and on computer climate models. "If you introduce polluted aerosols into the model the clouds are deeper, more energetic and produce more precipitation similar to the satellite measurements."

Zhang says the storm track over the Pacific is a major weather event and part of a complex global weather system, vulnerable to change. "If you change this weather pattern over the Pacific region, it is very likely that you are going to change the weather patterns over the West Coast and Canada. The weather patterns will be altered."

Scientists are also concerned that the movement out of Asia of polluted aerosols could affect climate at the Earth's poles. As more soot in the form of black carbon collects on ice packs, it attracts more heat from the sun and could accelerate melting.

Bill Chameides, a senior atmospheric scientist with the non-profit Environmental Defense says while the Texas A&M study focuses on Asia, the region is not alone in sending its pollution around the globe. "I think that it is also important to bear in mind that there is a good deal of pollution that comes from the United States that has an impact on our weather and our air quality."

U.S. pollution also has the potential to impact air quality around the globe, Chameides says, noting, "If China's pollution is having an impact on us, our pollution has the potential for having an impact on Europe."

Zhang says more research must be done to further evaluate the interaction between clouds and aerosols and what effect that might have on climate change. The Texas A&M study is published in the Proceedings of the National Academy of Sciences.