A two-mile thick layer of airborne crud across South Asia is damaging the region's agriculture, altering rainfall patterns, and putting hundreds of thousands of people at risk.

Worse, the impact of this man-caused pollution — ash, acids, aerosols, and other particles — could spread far beyond Asia, even worldwide, according to a study by the United Nations Environment Programme (UNEP) that will be discussed by delegates to the upcoming World Summit on Sustainable Development at Johannesburg, South Africa, Aug. 26-Sept. 4. More than 100 heads of state (not including President Bush, who will send Secretary of State Colin Powell) are among the 60,000 delegates expected to attend.

Scientists say this skyborne slop bucket, an outgrowth of the spectacular economic growth in the region, is expected to intensify over the next 30 years as the area's population rises to an estimated 5 billion. Already, the pollution layer is disrupting weather systems, including rainfall/wind patterns, and triggering droughts in the western part of the Asian continent. Much of India's cotton crop, for example, has been adversely affected this year because seasonal monsoons were late (but now are causing intense flooding).

Ten years after the Earth Summit at Rio de Janeiro spotlighted global pollution concerns, the problems in Asia “encapsulate the threats and challenges that we urgently need to address,” says Klaus Toepfer, executive director of UNEP. “How do we achieve economic growth without sacrificing the long-term health and natural wealth of the planet?”

The findings on the “Asian brown cloud,” as it is known, were compiled by 200 scientists, utilizing new satellite readings and computer modeling. Among those participating are Nobel laureate Paul Crutzen of the Max-Planck Institute for Chemistry in Germany and Prof. V. Ramanathan of the Scripps Institute of Oceanography in the United States. The researchers looked at effects of the haze on the region's climate rainfall, human health, and agriculture, and they are also trying to determine its impact on global warming. Among their findings:

  • The cloud is reducing the amount of sunlight/solar energy hitting the earth's surface by as much as 10 percent to 15 percent. This in turn reduces the evaporation of moisture that controls summer rainfall in the region.
  • Its heat-absorbing properties are warming the lower parts of the atmosphere “considerably.”
  • Precipitation over much of the region may be off by 20 percent to 40 percent, with droughts in some areas, flooding in others, damaging hundreds of thousands of acres of cropland.
  • India's rice harvest may be reduced as much as 10 percent, while acids falling in rain are damaging crops and trees over wide areas.
  • Several hundred thousand premature deaths could occur from increased respiratory disease.

Scientists now know that dust from storms in Mongolia, ash from volcanic eruptions, and microscopic particles from man-made pollution can travel across the globe in a week's time. Thus, the Asian brown cloud — if it continues to proliferate as predicted — may contribute to climatic changes in the United States.