A peculiar storm swept across the mountains of the Antarctic Peninsula in February of this year. Several scientists hunkered down in their tents as a torrent of horizontal-blowing snow washed through.

Erin Pettit found her way through the camp by following a series of red and green canvas flags flapping on bamboo poles. But when she paused and looked up, she saw something strange: a circle of blue sky directly overhead. It revealed that no new snow was actually falling—the blizzard consisted entirely of recycled snow—a thin layer of it, only a few feet thick, blowing along the ground.

The wind had scoured this snow off the surfaces of glaciers as it accelerated down the east side of the Peninsula’s mountains. When