© 2008 James Balog/Extreme Ice Survey
This remarkable image sequence captures a series of massive calving events at Columbia Glacier near Valdez, Alaska. Composed of 436 frames taken between May and September of 2007, it shows the glacier rapidly retreating by about half a mile (1.6 kilometers), a volume loss of some 0.4 cubic miles (1.67 cubic kilometers) of ice or 400 billion gallons (1.5 trillion liters) of water.
The time-lapse was taken as part of the ongoing Extreme Ice Survey (EIS), an ambitious project to capture global warming-induced glacial retreat in the act. Beginning in December 2006, photographer James Balog and his colleagues set up 26 solar-powered cameras at glaciers in Greenland, Iceland, Alaska, the Alps, and the Rocky Mountains. Each unit will take a photograph every daylight hour until fall 2009.
In 2008, Balog's team began to return to each of the camera sites to collect images. In the end, they will have more than 300,000 images to analyze and stitch together to produce more dramatic videos like this one.
This kind of multiyear effort, says Balog, is necessary to "radically alter public perception of the global warming issue."
Don't miss: Extreme Ice a NOVA/National Geographic Television special airing on PBS March 24, 2009 at 8:00 p.m.