In this image the skies over northern India are filled with a thick soup of aerosol particles all along the southern edge of the Himalayan Mountains, and streaming southward over Bangladesh and the Bay of Bengal. Most of this air pollution comes from human activities. This MODIS image was acquired on December 4, 2001.
However, recent research (Menon, et al. 2002) suggests that the observed trend toward increased summer floods in south China and drought in north China, thought to be the largest change in precipitation trends since 950 A.D., may have an alternative explanation: human-made absorbing aerosols, mainly black carbon soot, that alter the regional atmospheric circulation and contribute to regional climate change. If this interpretation is correct, reducing the amount of anthropogenic black carbon aerosols, in addition to having human health benefits, may help diminish the intensity of floods in the south and droughts and dust storms in the north.
Similar considerations apply to India, which has recently experienced droughts. India's air pollution, because it is also rich in black carbon, has reached the point where scientists fear it may have already altered the seasonal climate cycle of the monsoons.