The melting of glaciers in the Himalayas will have varying impact on the waters of the Indus, Ganges, Brahmaputra, Yangtze and Yellow rivers, according to a new Dutch research.
Scientists believe that the changes to the flow of meltwater due to global warming may have a “severe” impact on food security in some areas.
However, they also point out that the people living elsewhere are likely to see an increase in food productivity.
Overall, the food security of 4.5 per cent of 1.4 billion people in the region is threatened, the researchers say.
The lives of more than 1.4 billion people are dependent on waters of the Indus, Ganges, Brahmaputra, Yangtze and Yellow rivers.
"We show that meltwater is extremely important in the Indus basin and important for the Brahmanputra basin, but only plays a modest role for the Ganges, Yangtze and Yellow rivers," the BBC quoted the team from the Netherlands, as writing in the journal Science.
The researchers add: "The Brahmaputra and Indus basins are most susceptible to reductions of flow, threatening the food security of an estimated 60 million people."
They call mountains the "water towers of the world".
They say: "Snow and glacial melt are important hydrological processes... and changes in temperature and precipitation are expected to seriously affect the melt characteristics."
"The Yellow River, in particular, shows a consistent increase in early spring discharge.
"This is highly beneficial because most reservoirs are empty at the beginning of the growing season.
"An accelerated melt peak may thus alleviate a shortage of irrigation water in the drought-prone early stages of the growing season."