About 66 percent, which is 4 billion people, of the world's population lives without sufficient access to fresh water for at least one month of the year, according to a new paper published Friday in the journal Science Advances.
Previous studies calculated a lower number, estimating that between 1.7 and 3.1 billion people lived with moderate to severe water scarcity for at least a month out of the year.
Scientists, led by Dr. Arjen Hoekstra of the Netherlands' University of Twente, used a computer model that is both more precise and comprehensive than previous studies have used to analyze how widespread water scarcity is across the globe. Their model considers multiple variables including: climate records, population density, irrigation and industry.As the map below shows, this is not a spatially random problem. Some parts of the world--mostly very populated areas--are harder hit than others.
The HuffPost Science article mentions the role that drought may have played in setting off the Syrian civil war, and I've discussed that before. Throughout the Middle East, in particular, the combination of rapid population growth and dwindling water supplies is potentially explosive.