INDIA: Clouds Got In the Way.

THE INDIAN COASTAL CITY OF MUMBAI, FORMERLY BOMBAY, IS HOME TO INDIA'S VIBRANT FILM INDUSTRY ("Bollywood") and probably boasts more cell phones per capita than any other city on the subcontinent. But it is also home to Asia's largest slums. Half of Mumbai's population lacks running water or electricity, and the smoke from hundreds of thousands of open cooking fires joins with the sooty smoke from two-stroke auto rickshaws, belching taxis, diesel buses and coal-fired power plants in a symphony of air pollutants. Breathing Mumbai's inversion-trapped air, they say, is the equivalent of smoking 20 cigarettes a day.

The locally popular term for the hazy clouds that blanket Mumbai and other Indian cities, causing sore throats and aggravating allergies, is "fog." There's a general sense that it's a natural phenomenon, an impression mirrored in India's chauvinistic press. In the Indian Express, for example, Dr. J.G. Negi of the National Geophysical Research Institute opined recently that India "has nothing to worry about" when it comes to global warming, since India doesn't produce much greenhouse gas and, anyway, the higher levels of carbon dioxide will lead to "increased vegetation." Far from a warmer planet, Dr. Negi thinks we'll be in the grip of a new ice age by 2010.

In fact, however, India is the world's fifth-largest producer of global warming gas (the U.S. is first) and emissions there are bound to get worse as the population soars past one billion and private car sales (up 58 percent between 1998 and 1999) skyrocket.

Early signs that the climate is already changing are abundant. Last year, a heat wave killed hundreds of people and led to thousands of new cases of gastro-enteritis and cholera in New Delhi. Major droughts hit the eastern Orissa state in both 1999 and 1998, the latter resulting in 2,000 deaths. The heat wave continued into 2000, affecting seine 50 million people. Record temperatures dried up wells, rivers and streams and resulted in water crises in 11 of India's 31 states. In hard-hit Orissa, temperatures reached 118 degrees F. Government offices closed in the afternoon, trains carrying drinking water were mobbed, and prisoners rioted, shouting, "Give us water or kill us!"

"This heat wave is a signal to global warming," warns M. Lal of the Centre for Atmospheric Sciences. "India is simply following the global trend of higher temperatures." Lal predicted that India could heat up by as much as 37 degrees F by the end of the century, with "a major impact on the country's food production and water reserves."

But not all the effects are being felt on land. Last summer, a team of scientists funded by the National Science Foundation began a $25 million surveillance of the Indian Ocean and discovered a huge haze layer covering 10 million square miles, approximately the size of the continental United States. The scientists were astounded by the size of the cloud, which is made of tiny sun-blocking pollutant particles called aerosols. The haze, at an elevation of one to two miles, covers most of the northern Indian Ocean, the Arabian Sea west of Mumbai, and the Bay of Bengal. The source: air pollution from India and China, blown out to sea during the winter monsoon season.

Dr. Veerabhadran Ramanathan, a professor of atmospheric and ocean sciences at the Scripps Center for Clouds, Chemistry and Climate, is co-director of the so-called Indian Ocean Experiment (INDOEX) with Paul Crutzen of the Max Planck Institute for Chemistry in Germany. "The local effect is well-known," Ramanathan says, "because wintertime haze can sometimes close airports in India and Pakistan for weeks. But it was not known that it had spread over the entire ocean. It stunned us to discover how pervasive these aerosols are."

Dr. Ramanathan describes the haze as "a complicated chemical soup" of soot, sulfates, nitrates, ash and dust, generated by emissions from coal-burning power plants, biofuel cooking and diesel engines. The source is not a mystery, but the effect on the oceans is still unknown. "The haze causes a loss of sunlight striking the surface of the sea, and we are just starting research on how that affects photosynthesis and ocean plankton," Ramanathan says. Preliminary research indicates that solar radiation may have decreased by as much as 10 percent. In a complicated interaction, the haze produces both cooling and warming effects, making the task of measuring the final result that much more difficult. Sunlight also produces evaporation on the ocean surface, and blocking it has the potential of dramatically altering the whole hydrological cycle, a possible explanation for the droughts India has been experiencing. In yet another effect, aerosols are caught up in regional thunderstorms, falling back into the ocean as acid rain.

"The haze affects the optical properties of the clouds, making them brighter," says Dr. Joseph Prospero a professor of marine and atmospheric chemistry at the University of Miami and an INDOEX participant. Clouds also become more reflective and longer-lasting, a further cooling effect. Warming comes into it, too, because the pollutants are very dark and absorbing, taking in large amounts of sunlight. "When you redistribute solar energy within the atmospheric column, it has a considerable impact on the properties of clouds," Prospero says. "It's a complex system with a lot of feedbacks that are not clear yet."

Prospero adds that National Science Foundation grant reviewers had originally doubted that the researchers would find anything measurable. "But the size of what we saw didn't surprise me because I've been running cruises in that area for many years," he says. "And anyone who's ever been to India knows there's a lot of pollution there. It's scary, and it's the way it will go in all of Asia." CONTACT: Scripps Institution of Oceanography, [phone], www.sio.ucsd.edu.

JIM MOTAVALLI is editor of E and author of Forward Drive: The Race to Build "Clean" Cars for the Future (Sierra Club Books/Random House).