Amundsen Sea

The Amundsen Sea is a significant arm of the Southern Ocean.

It is located off the coast of Marie Byrd Land in western Antarctica. This sea sits between two specific landmarks. To the east lies Cape Flying Fish on the tip of Thurston Island. To the west lies Cape Dart on Siple Island. Cape Flying Fish marks the boundary between this sea and the Bellingshausen Sea. West of Cape Dart, there is no other named marginal sea between the Amundsen and Ross Seas.

Much of this sea is covered by ice. The Thwaites Ice Tongue is a large piece of ice that protrudes into the water. This region contains a massive area called the Amundsen Sea Embayment, or ASE. The ASE is roughly the size of the state of Texas. It serves as one of the three major ice-drainage basins of the West Antarctic Ice Sheet. The other two basins are the Ross Sea Embayment and the Weddell Sea Embayment. Some scientists believe this region acts as a weak underbelly for the West Antarctic Ice Sheet.

Two of the five largest glaciers in Antarctica flow into the Amundsen Sea. These are the Pine Island Glacier and the Thwaites Glacier.

Researchers have noted that the flow of these glaciers increased starting in the mid-2000s. This movement is a major concern for scientists. If these glaciers were to melt completely, global sea levels would rise by a significant amount. Some researchers suggest that losing these glaciers could destabilize the entire West Antarctic Ice Sheet. It might even affect sections of the East Antarctic Ice Sheet.

History shows how explorers mapped this frozen landscape. In 1928 and 1929, a Norwegian expedition led by Captain Nils Larsen explored the area. In February 1929, they named the sea after the Norwegian polar explorer Roald Amundsen. Later, the United States Navy used aerial photographs to delineate Pine Island Bay in December 1946. This bay is located at the southeast end of the Amundsen Sea. The Advisory Committee on Antarctic Names named the bay after the USS Pine Island. This ship was a seaplane tender and the flagship for the eastern task group of Operation HIGHJUMP.

Other areas like Russell Bay were also mapped later. The United States Geological Survey mapped this open bay between 1959 and 1966. It extends along the north sides of Siple Island, Getz Ice Shelf, and Carney Island. It was named for Admiral James S. Russell, who was the Vice Chief of Naval Operations.

These various discoveries help us understand the geography of the southern continent.

Several factors may contribute to the changing ice in this region. A subglacial volcano was detected north of the Pine Island Glacier near the Hudson Mountains. This volcano last erupted approximately 2,200 years ago. This was the largest known eruption in Antarctica within the last 10,000 years. While volcanic activity might contribute to glacial flow, most scientists favor a different theory. They believe warming ocean water is the main cause. This happens when deep ocean water rises due to variations in pressure systems. These pressure changes could be linked to global warming.

Recent data highlights the scale of ice loss in the Amundsen Sea. A 2023 study estimated that the area lost 3.3 trillion tons of ice between 1996 and 2021. This loss raised global sea levels by 9 millimeters. In 2005, the British Antarctic Survey measured the ice discharge rate. They found about 250 cubic kilometers of ice enter the Amundsen Sea Embayment each year. At that steady rate, the discharge alone could raise sea levels by 0.2 mm per year. A 2010 study also suggested the Pine Island Glacier might have passed a tipping point in 1996. This study projected a retreat of 4 kilometers by the year 2100.