Climate change threatens food supply of 60 million people in Asia

More than one billion people depend on the meltwater supplied by the Indus, Ganges, Brahmaputra, Yangtze and Yellow River. 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 forecasted the future river discharge and made predictions about food security in the basins of these five major rivers.

How important is meltwater?

"The role of meltwater in the Indus basin is much more significant than that in other river basins in Asia," according to Walter Immerzeel, hydrologist at Utrecht University and FutureWater. "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."

Food production

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," explains 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."

Uncertainty about glaciers

The size and discharge of Himalayan glaciers are experiencing significant decline due to climate change. "However, observed glacial decline varies greatly from region to region, and there is a high degree of uncertainty regarding the speed of decline," says Marc Bierkens, hydrology professor at Utrecht University. "However, the trends identified in the river discharge forecast do not take this uncertainty into account." The researchers based their results on a combination of hydrologic models, climate forecasts from five different climate scenarios, and satellite images depicting snow and ice, rainfall, and changes in the Earth's gravitational field.