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Pollution is disrupting rainfall
patterns in South Asia

A vast cloud of pollution over South Asia is damaging agriculture, disrupting rainfall patterns and putting the lives of hundreds of thousands of individuals at risk, according to the United Nations Environment Programme (UNEP).

In a report released today (12 August) UNEP says that the 'Asian Brown Haze' — a three-kilometre-deep mass of ash, acids, aerosols and other particles — is triggering droughts in Western Asia and could affect weather systems worldwide.

An international team of more than 200 scientists, who carried out the research on behalf of UNEP, say that forest fires and the burning of fossil fuels, wood, cow-dung and agricultural waste have caused the massive build-up of pollution in the region.

"More research is needed, but these initial findings clearly indicate that this [is] a major environmental hazard for Asia," says Klaus Toepfer, executive director of UNEP. "There are also global implications, not least because a pollution parcel like this … can travel half way round the globe in a week."

The pollution could be leading to "several hundreds of thousands" of premature deaths as a result of higher levels of respiratory diseases, the report suggests.

Furthermore, agriculture could be badly affected, as the pollution cloud is blocking out up to 15 per cent of the sunlight hitting the Earth's surface. Research carried out in India suggests that the cloud may already be reducing the winter rice harvests by as much as 10 per cent in this way.

Meanwhile, the cloud itself absorbs heat, leading to warming of the lower parts of the atmosphere. This combination of surface cooling and lower atmosphere heating appears to be altering the winter monsoon, leading to a sharp fall in rainfall over northwest Asia and increased rainfall along the eastern coast of the continent.

An action plan to tackle the pollution threat facing Asia is urgently needed, say the authors of the report, who worked on the Indian Ocean Experiment (INDOEX), and supplemented ground-based data with satellite readings and computer modelling.

"The huge pollution problems emerging in Asia encapsulates the threats and challenges that the [forthcoming World Summit on Sustainable Development] needs to urgently address," says Toepfer.

"We have the initial findings, and the technological and financial resources available. Let's now develop the science and find the political and moral will to achieve this for the sake of Asia, for the sake of the world."

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Photo credit: WHO/TDR/Crump