Most of the soot goes from the thousands of wood- and dung-burning cooking stoves in use all over South Asia, says the study led by William Lau, head of atmospheric sciences at NASA's Goddard Space Flight Centre in Greenbelt, Maryland.

The study, which looked at soot and dust concentrations in South Asia between 2000 and 2007 as well as air circulation patterns during that period, was made available at the Dec 7-18 climate summit here.

It says much of the soot - as well as dust - travels along air currents from southern Asia to the Tibetan plateau, where it accumulates. It also accumulates along the southern slopes of the Himalayas.
With a detailed numerical model, the study reinforces what Veerabhadran Ramanathan of the Scripps Institution of Oceanography in San Diego, California, has been saying - the soot and dust contribute as much to warming in the Himalayas as other greenhouse gases.

This is because the black soot and grey dust accumulate on the white snow and ice of th ...more

It is deliberate.