Print

Mail

wiki links

Asian pollution creating storms: scientists

Smog and air pollution from Asian cities have intensified storms over the Pacific Ocean, which will result in increased warming of the Arctic, scientists have warned. They report that the number of storm clouds in the region has increased by up to a half over the last 20 years as rapidly industrialized cities in countries such as India and China burn more coal as they grow.

The Pacific's storm system plays an important role in the circulation of the Earth's atmosphere, transporting heat and moisture to the northern latitudes.

Renyi Zhang, an atmospheric scientist at Texas A&M University, said this weather system had been affected by aerosols -- tiny particles of pollution such as soot produced when burning coal.

"Rapid industrialization and urbanization in Asia have caused severe air pollution over many countries, including China and India. Long-term satellite measurements have revealed a dramatic increase in aerosol concentrations over Asia," wrote Zhang yesterday in the Proceedings of the National Academy of Sciences.

"The increasing aerosol trend has been explained by sulphur dioxide and soot emissions, with an increase in sulphur dioxide emissions of 35 percent per decade over the same region."

Damian Wilson, an atmospheric scientist at the UK's Met Office in Exeter,England, said the Pacific storms formed in the central part of the ocean and headed west, hitting Canada and the northern US. "It's caused by the temperature difference between the northerly latitudes and the more southerly, tropical latitudes -- the storms mix the heat around," he said.

The weather system is active all year long, reaching its peak every winter in December and a minimum around July. Aerosols can affect weather by influencing the formation and duration of clouds, but to what extent this happens is not well understood.

"Aerosols affect the size of water droplets," Wilson said. "The more pollution particles there are in the air, the smaller the water droplets will be."

Smaller droplets are less likely to run into each other and coalesce into drops of rain, meaning clouds stay in the air longer.

To work out how pollution was changing the Pacific weather system Zhang led a team of researchers in analysing the information recorded on clouds over the Pacific from 1984 to 2005. They found that the clouds which make up many of the Pacific storms, called deep convective clouds, seemed to arise in connection with pollution emission from Asia.
This story has been viewed 1426 times.