Washington:A former chief economist at the World Bank has warned South Asian countriesthat even a moderate rise in temperatures could cause serious changes inenvironment.

These nations thus must prepare for the effects of globalwarming, even as they work to combat the human causes of climate change, saidSir Nicholas Stern, who led the eponymous Stern Review, which last yearexamined the economic impact of climate change.

In Washington for a two-day legislators' conference onclimate change, Stern who also served as senior vice-president of the WorldBank said, "In India and China, I think people understand the rising waterstress, and how vulnerable they are to melting glaciers and snows from theHimalayas."

"You have to give examples from around the world forpeople to really understand what's going on," he said using the analogy ofthe Himalayas as a sponge, moderating theimpact of precipitation as seasons change.

"Precipitation comes, and it's held there. That's howyou get water in the rivers. That effect will not be there if the glaciers andsnow are not there. Which means you'll get torrents during the wet season anddry rivers in the dry season. So you'll get a combination of flood anddrought," Stern said.

"We also don't know what effect that will have on themonsoon, and it could have quite a strong effect. That kind of thing is beingstudied now," he added.

The Indian Institute of Tropical Meteorologysupplies climate change data to SAARC nations, and is engaged in its largestrecruitment drive in a decade.

Agriculture represents a fourth of India's national income, and thatsector could be seriously disrupted by changes to the monsoon. Mitigationstrategies are needed to deal with the risks.

"We have to adapt how we handle water extraction, andirrigation. Water management is involved in all of this. Work has to be done onwhat crops would be resilient," Stern said.

"Urban areas throughout the region are also at risk, as watersupplies could be disrupted over time. Infrastructure must be upgraded forsanitation and drinking water, as well as for adequate storm drainage in areasprone to flooding," he said.