Scientists measuring glaciers in Antarctica and Greenland have expressed surprise at how fast the ice is melting.
The scientists from Britain found the ice is melting quickest where the glaciers meet warm ocean currents.
But the thinning extended far into the interior of the Greenland and Antarctic ice sheets.
One expert says it is difficult to predict how this would affect future sea levels.
The BBC reports scientists have known for several years that the giant glaciers have been melting, but this is the most accurate and comprehensive picture of the current state of these rivers of ice.
By using lasers on board a satellite orbiting the poles, researchers were able to get accurate measurements of the height and thickness of the ice.
Over 50 million of these readings confirmed that the worst losses are taking place where the glaciers flow into the sea.
In Greenland, the team found that 81 out of 111 glaciers surveyed were thinning at an accelerating pace.