Photo Gallery: Extreme Ice Survey

A crystalline iceberg drifts in Columbia Bay near Valdez, Alaska. The source of this iceberg, the Columbia Glacier, has lost more than 10 miles (16 kilometers) of ice since 1984.

In May 2007, members of the ongoing Extreme Ice Survey, including founder James Balog, were setting up cameras at Columbia Glacier when they witnessed one of the largest glacial calving events ever seen. A similar event filmed later at Greenland's Jakobshavn Glacier made the one at Columbia look small.