Rosenfeld picked up pollution tracks extending out of Adelaide, Australia, from a power plant, a lead smelter, oil refineries, and the port. He then used sensors onboard NASA's Tropical Rainfall Measuring Mission satellite to determine how much rain the clouds in the pollution plume produced. No rain fell from these clouds, while similar clouds in nearby unpolluted areas produced normal amounts of precipitation. Rosenfeld's data suggest that any heat effect could be canceled out by aerosol pollution, says Owen B. Toon, an atmospheric scientist at the University of Colorado at Boulder. Aerosol pollution in the tropics may reach far beyond suppressing local rainfall, says Hans F. Graf of the Max Planck Institute for Meteorology in Hamburg, Germany.
Tropical rain provides much of the energy needed for worldwide movement of air in the atmosphere.
This may explain why rainfall in the tropics has decreased despite predictions that global warming would make the area wetter, he says. The shininess that aerosol pollution generates on clouds may counteract some of the greenhouse effect by reflecting sunlight away from Earth, says Toon. However, aerosol pollution carries health hazards. All rights reserved. Subscribe to Science News .