Columbia Glacier, the fastest-moving glacier, is in Alaska. Its movement has increased from 15 (4.50 m) to 100 feet (30 m) per day during the past 20 years; researchers predict that the 33.5-mile-long (54 km) glacier will be transformed into a large fjord within 50 years.
About 800 feet (244 m) of the glacier rests underwater on the floor of Prince William Sound. As tides and storm waves buffet the glacier, huge blocks of ice break off and float as icebergs. This accelerates the downward movement of the glacier, in turn increasing the number of icebergs.
Icebergs are a threat to shipping lanes in the Sound, site of the 1989 Exxon Valdez oil spill. The ship left its shipping lane, ran aground, and spilled 10.8 million gallons of oil. More than 1,000 miles (1,600 km) of shoreline were polluted, killing 250,000 birds and thousands of sea otters, seals, and whales.
