Since 2004, glaciologist William Pfeffer has been photographing Alaska's Columbia Glacier. By monitoring where the glacier ends and the waters of Prince William Sound begin, Pfeffer is working to understand how coastal ice sheets contribute to rising ocean levels. Now, by piecing his photographs together, Pfeffer has produced this remarkable video documenting the glacier's rapid retreat.

This massive ice sheet has surrendered roughly 150 cubic kilometres of ice to the sea since it started receding in the early 1980s. One hundred fifty cubic kilometers! Imagine an ice cube measuring 3.3 miles along each edge. That's about how much ice we're talking about. In that time, researchers estimate that the glacier's terminus has retreated by about 20 kilometers.

Pfeffer's video visualizes this loss in a way that daily observation simply can't touch, and helps illustrate important information about the near-term effects of glacial melt on rising sea-levels.

"Seventy-six percent of the glacial mass of sea-level rise is coming from Arctic North America," explains glaciologist Martin Sharp to Nature News. "The Arctic is now the largest contributor to sea-level rise outside of the two largest ice sheets [The Antarctic and Greenland ice sheets]." [Nature]