A Darkening Sky
A smoky shroud over Asia blocks both sun and rain
V. "Ram" Ramanathan sat on an airliner heading south from Bombay. Ahead were the Maldives, an archipelago near the equator, where the atmospheric scientist from the Scripps Institution of Oceanography near San Diego planned to set up instruments to study haze and weather. He expected that results from the international project would come slowly and be of interest only to specialists. He was not prepared for what he saw just gazing out the plane window.
As he took off from Bombay, the layers of brown gunk in the sky were no surprise. Pollution controls on factories and vehicles are rare in his native land. Hundreds of millions of its citizens burn low-quality coal, wood, and cow dung for cooking and heating. But nearly 1,000 miles later over the open sea, the dirty pall still had not given way to blue sky and white clouds. "The haze just kept going and going. It didn't even seem to thin out. I was thinking, this is something big."
It is. Since Ramanathan's 1998 flight, scientists have realized that the pall he saw is just part of a vast brown cloud that often extends thousands of miles east, across China. A stew of dust, ash, and smoke from fires and industry, the cloud threatens the health of the billions who live under it. The fine particles, or aerosols, also warm some areas and cool others, drying up storm clouds and perhaps even shifting India's life-giving monsoon. In many places the haze swamps greenhouse gases as a climate-changing force, say scientists. The atmospheric havoc in Asia may even play a role in El Niño, the climate cycle now drenching the southern United States.
Much of this picture is still fuzzy, but scientists are working to sharpen it. Ramanathan and his Scripps colleague Paul Crutzen, a chemist and Nobel laureate, made a start with their Indian Ocean Experiment in the late 1990s, which studied haze from a score of ground stations and from aircraft. Their glimpses of the cloud's extent and impacts helped set off an explosion of similar studies across India, off Japan and Korea, and in China, which has launched the largest single scientific project in the country's history to analyze aerosols and climate. And it has spawned a new United Nations effort called Project Asian Brown Cloud. Led by Ramanathan and Crutzen, it is organizing a massive study of the pollution's sources and effects, and what to do about it.
In a way, Asia with its dirty, fast-growing industry is repeating on a far vaster scale the smoky evolution of European and U.S. industry in the 19th and early 20th centuries. Coal consumption in China, for example, was 50 percent higher than in the United States in 1999 and could be twice as high by 2010. Across Asia, coal heats houses and cooks meals. Smoke from agricultural burning and wildfires adds to the brew. In China, the haze sometimes starts as dust blowing off western deserts, "but it picks up all kinds of toxic pollutants as it travels," says F. Sherwood Rowland, a University of California-Irvine chemist who received a Nobel Prize for work on ozone. "We can detect Asian aerosols blowing all the way across the U.S."
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