France, June 7 -- From concrete towers and motorways to glass, microchips and cosmetics, modern economies depend on sand. Yet the vast scale of sand extraction remains largely ignored, despite mounting concerns among scientists over its environmental and social consequences.

According to the latest report from the United Nations Environment Programme (UNEP), nearly 50 billion tonnes of sand are extracted worldwide every year, and demand for buildings is expected to rise by 45 percent by 2060.

"To give an idea of the scale, it would be equivalent to building a wall 27 metres high and 27 metres wide that circles the entire Equator every year," says Pascal Peduzzi, director of GRID-Geneva, UNEP's environmental data centre. "You cannot extr...