The Columbia Glacier is in the Chugach Mountains on the north coast of Prince William Sound, Alaska. The glacier starts from an ice field near Mount Witherspoon and flows generally southeast for 40 miles (64.5 km), descending 10,000 feet (3,050 meters), to sea level in Columbia Bay, about 28 miles (28 km) southwest of Valdez. Changes to the Columbia Glacier have been documented since the Harriman Alaska Expedition in 1899, that named the bay and glacier after Columbia University in New York.
When British explorers first charted the glacier in 1794, the glacier terminus (or toe) was at Heather Island near the mouth of Columbia Bay. For most of the 20th century, the terminus was stranded on a moraine just north of the island. In the 1970s, several glaciologists such as Austin Post of the U.S. Geological Survey, correctly predicted that the glacier would start a rapid retreat once it melted off the moraine exposing the glacier face to relatively warm seawater.
Since 1982, the terminus has retreated about 12 miles (20 km) from the moraine. The abundance of ice discharged by the retreat contributed to the course deviation of the tanker Exxon Valdez prior to grounding on Bligh Reef in 1989. The glacier’s speed of retreat reached a maximum of nearly 98 feet (30 m) per day in 2001 when it was discharging icebergs at a rate of approximately 1.7 cubic miles (7 cu km) per year. The retreat has been accompanied by nearly 500 m (1,600 ft) of thinning. The glacier’s retreat should slow around 2020 when the terminus recedes from tidewater. Read more here and here. Explore more of the Columbia Glacier here: