South Asia is the world's most climate-vulnerable region, its fast-growing populations badly exposed to flood, drought, storms and sea-level rise, according to a survey of 170 nations.Of the 16 countries listed as being at "extreme" risk from climate change over the next 30 years, five are from South Asia, with Bangladesh and India in first and second place.The Climate Change Vulnerability Index, compiled by a British-based global risks advisory firm, Maple croft, is intended as a guide for strategic investment and policy making."Very minor changes to temperature can have major impacts on the human environment, including changes to water availability and crop productivity, the loss of land due to sea-level rise, and the spread of disease . "Bangladesh is rated No1 because of a double whammy. It has the highest risk of drought and the highest risk of famine.It is also struggling with extreme poverty, high dependence on agriculture -- the economic sector most affected by climate change -- and a government that is the least capable of coping with climate impacts