Europe South Asia Asia Pacific Americas Middle East Africa BBC Homepage World Service Education

Front Page



UK Politics







Talking Point

In Depth

On Air

Low Graphics

Friday, June 11, 1999 Published at 17:20 GMT 18:20 UK


Pollution cloud threatens Asia

A thick brown cloud of pollution the size of the United States has formed over the Indian Ocean, contributing to acid rain and cutting the amount of sunlight reaching the water.

The BBC's Clare Arthurs: The cloud contains soot, chemicals and carbon monoxide
The cloud, a mixture of pollutants from vehicle and industrial emissions, could wreak havoc on the region's climate and marine life.

Scientists sponsored by the US National Science Foundation spent six weeks earlier this year tracking the cloud with aircraft, ships, balloons and satellites.

[ image: The INDOEX project has mapped the extent of the cloud]
The INDOEX project has mapped the extent of the cloud
The Indian Ocean Experiment, or INDOEX, revealed that the affected area includes most of the northern Indian Ocean, the Arabian Sea, and much of the Bay of Bengal - nearly 10m square km in total.

The cloud rises three kilometres into the Earth's atmosphere, and consists of tiny particles of soot, chemicals and carbon monoxide - by-products of burning fossil fuels.

During the winter monsoons, the cloud blows out from Asia over the ocean, and during the summer wet season it reverses direction to move back over the land.

Levels of sunlight reduced

[ image: Pollution affects many Asian cities]
Pollution affects many Asian cities
Scientists from the Scripps Institution of Oceanography in San Diego, which coordinated the project, say the pollution is unprecedented in the region's history, and will get worse as the population increases.

Tiny particles in the cloud reflect the sun's rays, cutting its heat by up to 10%.

In the ocean, less sunlight could threaten the survival of water-plants and plankton - key organisms in the world's food chain. Reduced sunlight also means that less water evaporates from the ocean - leading to lower rainfall and increasing the risk of drought.

Scientists now want to discover how permanent the cloud is, and whether it is growing.

Advanced options | Search tips

Back to top | BBC News Home | BBC Homepage | ©

Sci/Tech Contents

Relevant Stories

28 Apr 99 | Asia-Pacific
Return of Asian haze warning

06 Apr 99 | Sci/Tech
Bangkok overheating

14 Jun 99 | Sci/Tech
Indian ocean haze startles scientists

Internet Links


National Science Foundation


The BBC is not responsible for the content of external internet sites.

In this section

World's smallest transistor

Scientists join forces to study Arctic ozone

Mathematicians crack big puzzle

From Business
The growing threat of internet fraud

Who watches the pilots?

From Health
Cold 'cure' comes one step closer