10/28/2014 09:05 am ET Updated Dec 28, 2014

In Alaska's Kenai Fjords National Park, a 700-Square-Mile Icefield Shrinks, While a Popular Glacier Shows Big One-year Retreat

The huge Harding Icefield on Alaska's Kenai Peninsula shed some of its mass over the past year and Exit Glacier, which spills out of that 700-square-mile icefield, retreated more than in any other single year since annual mapping of the terminus began in 2005, according to National Park Service data.

The measurements, taken by scientists working in Kenai Fjords National Park, are part of a long-term program to monitor changes in the park's glaciers and their mass.

On the icefield, measurements taken this fall at four of the six monitoring sites showed a net loss of mass, with all of the past winter's snowfall melted out by the end of September. The biggest melt was at a site 1,745 feet up the icefield, the lowest-elevation of the six sites monitored by the Park Service, where nearly 28 vertical feet of ice was lost, according to measurements.

At Exit Glacier, a major Alaska tourism attraction, the terminus retreated 187 feet in the past year, according to measurements taken last month. About 80 percent of that retreat happened during the summer, according to the Park Service measurements.