Ian Joughin/AP

Fueled by global warming, polar ice sheets in Greenland and Antarctica are now melting three times faster than they did in the 1990s, a new scientific study says.

Ian Joughin/AP

An ice sheet in Greenland, which covers most of the island, is a pressing issue, researchers said.

Ian Joughin/AP

Scientists blamed man-made global warming for the melting.

Ian Joughin/AP

Since 1992, ice sheets at the poles have lost nearly 5 trillion tons of ice, the study said, raising sea levels by about a half inch.