A global shortage of sand is prompting black-market gangs to steal large amounts from rivers and beaches. Scientists are warning that the global supply of sand is slipping through our fingers. Statistics show that worldwide, we go through 50 billion tons of sand every year – twice the amount produced by every river in the world during the same period. According to writer and journalist Vince Beiser, who wrote a book on the subject, “Sand is the essential ingredient that makes modern life possible. And we are starting to run out.” That’s mainly because the number and size of cities is exploding, especially in the developing world, Beiser told Business Insider. “ Every year there are more people on the planet, and every year more of them move to cities. Since 1950, the world’s urban population has ballooned to over 3.9 billion from 746 million,” he said. The demand for construction aggregates will rise by 5.2 percent annually to 51.7 billion t