Asian brown cloud

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The Asian brown cloud is a layer of air pollution that covers parts of the northern Indian Ocean, India, Pakistan, and parts of South Asia, Southwest Asia, and China.[1] [2] Viewed from satellite photos, the Cloud appears as a giant brown stain hanging in the air over much of Asia and the Indian Ocean.

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[edit] Causes

In some humidity conditions, it forms haze. It is created by a range of airborne particles and pollutants (e.g. woodfires, cars, and factories), characteristic of biomass burning and industrial emissions due to incomplete burning.[3] The cloud is associated with winter monsoon (December to April) during which there is no rain to wash pollution from the air.

This pollution layer was observed during the Indian Ocean Experiment (INODEX) intensive field observation in 1999. Subsequently the United Nations Environment Programme (UNEP) has been supporting a project called ABC (still ongoing in 2007).

Although aerosol particles are generally associated with a global cooling effect, recent studies have shown that they can actually have a global warming effect in certain regions such as the Himalayas.[4] The warming effect of the Asian Brown Cloud may be an important factor in the retreat of the Himalayan glaciers. The United Nations Environment Program is worried that Asian glacial melting could lead to water shortages and floods for the hundreds of millions of people who live downstream.

A recent CSIRO study found that the Asian Brown Cloud is also affecting rainfall in Australia.[5]

[edit] Remedies

Because human activity is the main cause of the Asian Brown Cloud, it is possible that behavioral changes might reduce its harmful effects. For example, much of the cloud comes from people burning wood and dung to cook their food. By converting to cleaner fuels, it may be possible to reduce the size of the cloud.[6]

[edit] References

  1. ^ Srinivasan, J (September 2002). "Asian Brown Cloud – fact and fantasy". Current Science 83 (5): 586-592. 
  2. ^ Ramanathan, Veerabhadran (2001). "Indian Ocean experiment: An integrated analysis of the climate forcing and effects of the great Indo-Asian haze". Journal of Geophysical Research 106 (D22): 28371-28398. 
  3. ^ Taylor, David (January 2003). "The ABCs of Haze". Environmental Health Perspectives 111 (1). 
  4. ^ Ramanathan, Veerabhadran (August 2007). "Warming trends in Asia amplified by brown cloud solar absorption". Nature 448: 575-578. doi:10.1038/nature06019. 
  5. ^ Rotstayn, Leon (May 2007). "Have Australian rainfall and cloudiness increased due to the remote effects of Asian anthropogenic aerosols?". Journal of Geophysical Research 112 (D09202). 
  6. ^ Asian cloud blamed for glacial melting, ABC News Online

[edit] See also

[edit] External links

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