11/04/2011, 00.00
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South Asian pollution spurs cyclone formation in the Arabian Sea

Since the '90s, the "brown cloud" that covers India, Pakistan and the northern Indian Ocean has grown six times. Its’ influence on the monsoon and the decrease of the glaciers of the Himalayas already highlighted. Research shows it is the cause of the storms that have intensified in recent years, and causing heavy losses of lives and billions of dollars in damage.
London (AsiaNews / Agencies) - South Asian pollution is helping the formation of monstrous cyclones over the Arabian Sea, which cost hundreds of deaths and billions of dollars in damage, highlights a study published in Nature on the haze, called "Asian brown cloud" that covers India, Pakistan and much of the northern Indian Ocean.

More than three kilometres thick, the cloud contains brownish particles of soot and sulphate produced by coal plants, exhaust and low burning biomass. Previous research had shown its influence in the change of the monsoon and decline of the glaciers in the Himalayas.

Now, a group of scientists led by Amato Evan of the University of Virginia, has studied patterns of cyclones in the Arabian Sea from 1979 to 2010. As a result, historically there were two or three cyclones a year and they were of low strength, even if were able to create violent storms at sea.

The few storms were related to the monsoon season, which they usually preceded or followed, usually one in May-June, and two or more between August and December. But sometime in the last ten years the model has changed, with the onset of storms in the weeks immediately preceding the monsoon season. They include a cyclone in June 1998 that caused the deaths of some three thousand people in the Indian state of Gujarat.

In June 2007, level five cyclone Gonu, killed 49 people in Oman (pictured) and Iran and caused damage to the tune of four billion dollars. In June 2010, 26 people died in Pakistan and Oman, because of the level four cyclone Phet.

The research presented now says that since the 90's the "brown cloud" of particles has increased six-fold in volume. Its dark color absorbs sunlight, making it a source of heat and causing a cooling of the ocean below, which in turn creates a circulation of winds and an updraft from the sea to the atmosphere.

Cyclones are born this way and given the relatively small size of the Arabian Sea – compared with, for example, the Atlantic Ocean - more than half of it touches land. And even when they are weak, they can cause severe destruction and loss of life.

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