In the last hundred years, many of the planet’s largest lakes have begun drying up, from the Aral Sea in central Asia, which was once the world’s fourth largest and which has lost more than 90 percent of its volume in recent decades, to Lake Mead, which supplies much of Las Vegas’s water and has lost as much as 400 billion gallons in a single year. Lake Poopó, once Bolivia’s second biggest, has completely disappeared; Iran’s Lake Urmia has shrunk more than 80 percent in thirty years. Lake Chad has more or less evaporated entirely.
