Thwaites Glacier

Thwaites Glacier, segment of the West Antarctic Ice Sheet (WAIS) that drains parts of Ellsworth Land in Antarctica into Pine Island Bay in the Amundsen Sea. The Thwaites Glacier has the world’s widest glacial interface with the ocean, extending roughly 75 miles (120 km), and the collapse of this glacier could cause a catastrophic rise in sea levels worldwide. Some 30 miles (50 km) of the glacier’s ocean front terminates in an ice shelf that floats above Pine Island Bay. The grounding line of the ice shelf extends downward from the sea surface to depths between about 2,600 and 3,940 feet (roughly 800 and 1,200 meters), where it makes contact with the bedrock and buttresses a significant portion of the Thwaites Glacier against collapse. The glacier covers approximately 74,100 square miles (192,000 square km)—an area about the size of the U.S. state of Florida and slightly smaller than the island of Great Britain. It is named for American glacial geologist and geomorphologist Frederik T. Thwaites.

The Thwaites Glacier has the world’s widest glacial interface with the ocean, extending roughly 75 miles (120 km). Alone, the Thwaites Glacier is responsible for about 4 percent of current global sea level rise. However, scientists report that the temperatures of the bottom waters in the Amundsen Sea have been increasing from continued global warming. There is evidence that the warming waters are slowly melting submerged ice at the base of the glacier, thereby making the glacier more unstable and raising concerns that it will collapse. Already, this process is thought to have accelerated the glacier’s calving rate from 11 billion tons (10 billion metric tons) per year in 1990 to about 88 billion tons (80 billion metric tons) per year by 2020—some 55 billion tons (about 50 billion metric tons) more ice than can be replenished by current snowfall rates. Such factors underscore an expectation by scientists that the glacier will collapse sometime during the 2040s and hasten the flow of ice off the WAIS into the ocean. Studies suggest that this process will eventually result in an increase in sea levels of up to 25.6 inches (65 cm) worldwide—a prospect that has caused some researchers to label the Thwaites Glacier the “Doomsday Glacier.”