This report, written by a team of international scientists and published by the UN Environment Programme (UNEP), explores the effects of 'atmospheric brown clouds'(ABCs) on regional climate, agriculture and human health.

ABCs are large plumes of pollutant gases that result from burning fossil fuels and biomass. The authors of the UNEP report examine the spread of ABCs — particularly in Asia — and discuss their likely impacts, including decreases in the Indian summer monsoon rainfall, accelerated glacial retreat and increases in surface ozone.

They suggest that ABCs threaten water and food security in Asia, impact human health and may mask the warming effects of climate change by 20 – 80 per cent. The authors recommend an international response to tackle the twin effects of ABCs and greenhouse gases, and the unsustainable development that underpins them.