BBC: With the job of co-ordinating polar bear patrols in Alaska, biologist Mike Pederson is used to encounters with the predator.
But one dark night when he was called out to investigate a sighting of a polar bear straying towards human homes, he had a very close shave indeed.
He had to climb a ridge of sand to get to where the bear had last been seen, and when he got to the top he found it waiting on the other side.
"I saw the black of its nose," he recalls. "And I just started running towards...