Enormous chunks of ice melting into the sea.

The video comes from photographer James Balog's film, . The two guys on the bluff at the beginning are part of Balog's Extreme Ice Survey team, which maintains scores of time-lapse cameras overlooking glaciers in Greenland, Iceland, Alaska, Canada, the Rockies and the Himalayas. During daylight hours, they watch and record. Then they share what they see with scientists and National Geographic.