The javelins are designed to only partially embed into the ice, so that they are still able to communicate with satellites. To that end the devices are equipped with small parachutes and "ice brake" fins to keep them from disappearing beneath the ice sheet when they crash land, Gudmundsson said.
Like many glaciers in polar regions, the Pine Island Glacier's expanse of ice doesn't stop when it reaches the ocean. Instead, the ice flows into the sea, where it floats atop the water, forming a platform of ice called an ice shelf. Measurements have shown that the Antarctic Ocean is warmer than it used to be, and is melting the bottom of this ice shelf. That produces less resistance for the glacier on land, which, as a result, slides toward the ocean faster than before, Gudmundsson said.
And behind the Pine Island Glacier is an even larger section of the West Antarctic Ice Sheet, one of the largest in the world. The glacier acts like a plug in a leaky dam, and if it collapses, it could have devastating consequences for global sea levels, he added.