Alaska's Columbia Glacier No Longer Grounded - Floating Glaciers Produce Fewer, Larger Bergs

[hatrack]

An Alaskan glacier has lost its footing with the seafloor and is floating in the ocean, new first-of-their-kind observations show.

EDIT

The study of Columbia Glacier, a tidewater glacier, shows the first detailed observation of a glacier undergoing a transition from grounded to floating. Tidewater glaciers flow directly into the ocean, ending at a cliff in the sea, where icebergs are formed. Prior to this study, Alaskan tidewater glaciers were believed to be exclusively grounded and unable to float without disintegrating.

The switch in glacier style is important, because unlike floating glaciers, grounded glaciers calve icebergs nearly continuously, which means they generally form smaller icebergs. The Columbia Glacier had been continuously calving so that ice was always flowing down toward the sea, creating icebergs roughly every hour.

Floating glaciers, such as the one that developed at Columbia in 2007 produce more massive icebergs once a week, much slower than grounded glaciers that form icebergs hourly. The reason Columbia Glacier began floating may have been because it was receding so fast that its extension into the water began floating before it was able to break off into an iceberg, the study suggests.

EDIT

http://www.csmonitor.com/Science/2010/0716/Alaskan-glacier-detaches-itself-from-seafloor-goes-rogue