Air Pollution, Himalayan Monsoons, & Climate Change

Pollution may hit Himalayan monsoon clouds
Mon Oct 13, 2008 5:09pm EDT

By Alister Doyle, Environment Correspondent

OSLO (Reuters) – Higher levels of pollution in Asia may affect the formation of
clouds high in the Himalayas, perhaps disrupting monsoons and speeding a thaw of
glaciers, according to a study on Monday.

The report, by scientists in France and Italy, found microscopic particles in the
air that can be seeds for water droplets at a Nepalese mountain observatory, the
highest in the world at 5,079 meters (16,660 ft) above sea level.

It was the first time scientists had observed such particles forming so high, far
above those seen in previous studies from Europe and Japan.

“We think it’s because there’s a lot of pollution in the valleys which rises and
meets clean air masses higher up. This creates new particles,” Karine Sellegri at
the Universite Blaise Pascal in France, one of the authors, told Reuters.

The study, in the U.S. journal Proceedings of the National Academy of Sciences, said
the particles might come from smoke from people burning wood in Himalayan valleys.
Or some might have a natural origin, from vegetation.

Still, the scientists pointed to wider risks of the cloud-forming
mechanism.

“Rising air pollution levels in South Asia will have worldwide
environmental consequences,” they wrote.

“Transport of pollutants from the densely populated regions of India, Pakistan,
China and Nepal to the Himalayas may lead to substantial radiative forcing (warming
effect) in South Asia.”

In turn, that could affect the formation of monsoons, disrupt the regional climate
and have “dramatic impacts on glacier retreat” in the Himalayas, they wrote.

The U.N. Climate Panel said last year that Himalayan glaciers, which feed rivers on
which hundreds of millions of people depend, could shrink to 100,000 square kms
(38,610 sq miles) by 2030 from 500,000 now because of global warming.

Sellegri added, however, that it was too early to know exactly what impact rising
pollution would have in the Himalayas. “We need more modeling,” she said.

(Editing by Louise Ireland)

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