By Damian Grammaticas
BBC News, Varanasi
Up to a billion people in Asia could be adversely affected by global climate change, a United Nations report is expected to conclude.
If the Ganges flow drops, millions could struggle to find drinking water
Some of the warnings likely to be included in the report are acute water shortages, hunger and the continent's rivers running low.
It is the second in a series of reports by the UN's Intergovernmental Panel on Climate Change (IPCC).
It says India is likely to be among the first major nations to be affected.
The panel says the world's poorest countries are likely to feel some of the worst effects of global warming.
One of the major world rivers on the endangered list is India's Ganges.
It is one of the great rivers of the Indian-subcontinent, the source of life for hundreds of millions of people.
Many revere the Ganges as a goddess.
In the holy city of Varanasi, temples line the banks of the river.
For several kilometres, steps descend to the water's edge and as the giant river flows gently past, thousands of people bathe in its holy waters every day.
Most of the water flows from glaciers high in the Himalayan mountains.
Only the polar ice sheets hold more fresh water.
But global warming means many of those glaciers are melting fast and could vanish in the coming decades.
The result would be catastrophic.
The worst predictions say water flow in the Ganges could drop by two-thirds.
They say 400 million people could struggle to find drinking water.
Farmers would not be able to irrigate their land.
Hydro-electric power stations would generate less electricity.
India's much-vaunted economic growth could be affected and India could be one of the big losers from climate change.