London: Climate change will drastically reduce the flow of snow and ice meltwater in the Himalayas, threatening the food security of more than 60 million Asians, warn ecological researchers.
The Indus and Brahmaputra basins are expected to be the most adversely affected, while in the Yellow River basin the availability of irrigation water will actually increase.
More than one billion people depend on the meltwater supplied by the Indus, Ganges, Brahmaputra, Yangtze and Yellow River.
"The role of meltwater in the Indus basin is much more significant than that in other river basins in Asia," said Walter Immerzeel, hydrologist at Utrecht University and FutureWater in the Netherlands.
"The downstream sections of the Indus are dry, are home to one of the largest irrigation networks in the world and are completely dependent on meltwater," said Immerzeel.
The snow and ice reserves situated upstream are important in sustaining the availability of water downstream.
Researchers from Utrecht University and FutureWater have calculated the reduction in glacier and snow coverage and forecast the future river discharge.
They have also made predictions about food security in the basins of these five major rivers.
Climate change will ultimately result in declining discharge levels of the major Asian rivers, impacting the volume of irrigation water available.
"Our model calculations show that the Brahmaputra and Indus are the most vulnerable. According to our estimates, this will threaten the food security of the approximately 60 million inhabitants of these areas by the year 2050," said Immerzeel.
"However, the opposite is also possible. In the Yellow River basin, an increase in wintertime rainfall is expected, resulting in increased availability of water early in the growing season."
The size and discharge of Himalayan glaciers are experiencing significant decline due to climate change.
The researchers based their results on a combination of hydrologic models, climate forecasts, and satellite images. These findings were published in Science.