New Delhi, July 14 - Soot from the wood-based cooking fires used by 70 percent of Indians is forming a cloud of pollutants that is impeding the monsoon winds, according to a senior scientist.

The Asian Brown Cloud, as the blanket of pollutants over South Asia and the Tibetan plateau is called, is not only weakening the monsoon but is responsible for half the warming observed in the Himalayas, Syed Iqbal Hasnain, senior fellow at The Energy and Resources Institute, said here Monday evening.

He was delivering a talk organised by the Indian Mountaineering Foundation on the melting of Himalayan glaciers due to climate change. Scientists fear the melting will lead to water scarcity in the north and south of the Himalayas, affecting well over a billion people.

'With 70 percent of the Indian population using biomass for cooking, the Asian Brown Cloud covers the entire sub-continent at a height of around 3,000 feet,' said Hasnain, a former vice chancellor of Kozhikode University and formerly from New Delhi's Jawaharlal Nehru University.

The effect of this cloud gets worse in the cold atmosphere of the Himalayas where the soot gathers and impedes wind, he explained. Apart from the weak monsoon that is causing consternation in India now, the cloud also held up the westerly winds in winter.

'There was not much of a winter in Kashmir this year,' Hasnain pointed out. 'And hardly any winter snow.' It had a bad effect on horticulture.

Scientists have measured the average temperature in the Himalayas had risen by 1.2 degrees Celsius in the last 100-odd years.