| Columbia Glacier | |
|---|---|
Columbia Glacier from Prince William Sound. |
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| Type | Tidewater glacier |
| Location | Descending from the Chugach Mountains to Prince William Sound, Alaska. |
| Area | 1,000 km2 (400 sq mi) |
| Length | 51 kilometres (32 mi) |
| Thickness | 550 m (1,800 ft) |
| Terminus | Sealevel (Prince William Sound) |
| Status | Retreating |
The Columbia Glacier is a glacier in Prince William Sound on the south coast of the U.S. state of Alaska. It is one of several glaciers in the area named for elite U.S. colleges, in this case Columbia University, and was named by the Harriman Alaska Expedition in 1899. It is one of the fastest moving glaciers in the world, and has been retreating since the early 1980s.[1]
The Alaska Marine Highway vessel M/V Columbia is named after the Columbia Glacier.
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The glacier twists its way through western Alaska's Chugach Mountains. The bald streak at the bottom of the mountains, called the trimline, shows this glacier has lost 1,300 feet (400 m) of thickness. It has also retreated 10.5 miles (16.9 km) since that measurement was taken.
Speed at the terminus reached a maximum of nearly 30 metres (98 ft) per day in 2001, when the glacier was discharging icebergs at approximately 7 cubic kilometres (1.7 cu mi) per year; the glacier has subsequently slowed down, resulting in an increase in retreat rate. The terminus has retreated a total of 16 kilometres (9.9 mi) at an average rate of approximately 0.6 kilometres (0.37 mi) per year since 1982. Retreat has been accompanied by nearly 500 metres (1,600 ft) of thinning at the present position of the terminus. In the next few decades it is expected to retreat another 15 kilometres (9.3 mi), to a point where the bed of the glacier rises above sea level. Tidewater glacier advance and retreat is not directly forced by climate (adjacent tidewater glaciers may be simultaneously advancing and retreating), but rapid retreat appears to be triggered by climate-forced long-term thinning.