Climate change will increase the number of people at risk of absolute water scarcity by 40 percent this century, according to a German institute.
Ten in 100 will have less than 500 cubic meters (132,000 gallons) of water available a year, up from 1-2 today, should Earth warm by 3 degrees Celsius (5.4 degrees Fahrenheit) above pre-industrial levels and populations grow, according to the Potsdam Institute for Climate Impact Research. The global average is about 1,200 cubic meters, and much greater in industrialized nations, PIK said, citing its and other analysts.
"Water scarcity is a major threat for human development as for instance food security in many regions depends on irrigation," said Qiuhong Tang of the Chinese Academy of Sciences, who co-wrote the study. "Agriculture is the main water user worldwide."
As the world warms, the southern U.S., Mediterranean, Middle East and southern China probably will see lower water availability as southern India, western China and parts of East Africa may experience substantial increases, PIK said.
About 1.3 billion of Earth's 7 billion people already live in water-scarce regions, PIK said in October. With greenhouse gas emissions at a record, the UN says the world is on track to surpass a 2-degree Celsius temperature increase by 2100 that would raise sea levels and trigger more violent storms.
More precipitation "may cause water-logging, flooding and malfunctioning or failure of water-related infrastructure," Tang said. "So the overall risks are growing."
The study was conducted by research institutes from around the world based on an analysis of 11 global hydrological models, PIK said.