Scientists watching Antarctica's Pine Island Glacier from space have noticed with some alarm that it has been surging toward the sea.
If it were to melt entirely, global sea levels would rise by several feet.
The glacier is really, really remote. It's 1,800 miles from McMurdo, the U.S. base station in Antarctica, so just getting there is a challenge. Scientists have rarely been able to get out to the glacier to make direct measurements.