Amundsen Sea



The Amundsen Sea is an arm of the Southern Ocean off Marie Byrd Land in western Antarctica. It lies between Cape Flying Fish (the northwestern tip of Thurston Island) to the east and Cape Dart on Siple Island to the west. Cape Flying Fish marks the boundary between the Amundsen Sea and the Bellingshausen Sea. West of Cape Dart there is no named marginal sea of the Southern Ocean between the Amundsen and Ross Seas. The Norwegian expedition of 1928–1929 under Captain Nils Larsen named the body of water for the Norwegian polar explorer Roald Amundsen while exploring this area in February 1929.

The sea is mostly ice-covered, and the Thwaites Ice Tongue protrudes into it. The ice sheet which drains into the Amundsen Sea averages about 3 km in thickness; roughly the size of the state of Texas, this area is known as the Amundsen Sea Embayment (ASE); it forms one of the three major ice-drainage basins of the West Antarctic Ice Sheet.

Embayment


The ice sheet that drains into the Amundsen Sea averages about 3 km in thickness. It is roughly the size of the state of Texas and is known as the Amundsen Sea Embayment (ASE); it forms one of the three major ice drainage basins of the West Antarctic Ice Sheet along with the Ross Sea Embayment and the Weddell Sea Embayment.

Some scientists proposed that this region may be a weak underbelly of the West Antarctic Ice Sheet. The Pine Island and Thwaites Glaciers, which both flow into the Amundsen Sea, are two of Antarctica's largest five. Researchers reported that the flow of these glaciers increased starting in the mid-2000s; if they were to melt completely, global sea levels would rise by about 0.9–1.9 m. Other researchers suggested that the loss of these glaciers would destabilise the entire West Antarctic ice sheet and possibly sections of the East Antarctic Ice Sheet.

A 2004 study suggested that because the ice in the Amundsen Sea had been melting rapidly and was riven with cracks, the offshore ice shelf was set to collapse "within five years". The study projected a sea level rise of 1.3 m from the West Antarctic Ice Sheet if all the sea ice in the Amundsen Sea melted.

Measurements made by the British Antarctic Survey in 2005 showed that the ice discharge rate into the Amundsen Sea embayment was about 250 km3 per year. Assuming a steady rate of discharge, this alone was sufficient to raise global sea levels by 0.2 mm per year.

A subglacial volcano was detected just north of the Pine Island Glacier near the Hudson Mountains. It last erupted approximately 2,200 years ago, indicated by widespread ash deposits within the ice, in what was the largest known eruption in Antarctica within the prior 10 millennia. Volcanic activity may be contributing to the observed increase of glacial flow, although the most popular theory is that the flow has increased due to warming ocean water. This water has warmed due to an upwelling of deep ocean water due to variations in pressure systems, which could have been affected by global warming. In January 2010, a modelling study suggested that the "tipping point" for Pine Island Glacier may have been passed in 1996, with a retreat of 200 km possible by 2100, producing a corresponding 24 cm of sea level rise. It was suggested that these estimates were conservative. The modelling study also stated that "Given the complex, three-dimensional nature of the real Pine Island glacier ... it should be clear that the [...] model is a very crude representation of reality."

A 2023 study estimated that the area lost 3.3 trillion tons of ice between 1996 and 2021, raising sea levels by 9 millimeters.

Pine Island Bay
Pine Island Bay (-74.83333°N, -102.66667°W) is a bay about 40 mi long and 30 mi wide, into which flows the ice of the Pine Island Glacier at the southeast extremity of the Amundsen Sea. It was delineated from aerial photographs taken by United States Navy (USN) Operation HIGHJUMP in December 1946, and named by the Advisory Committee on Antarctic Names for the USS Pine Island, seaplane tender and flagship of the eastern task group of USN Operation HIGHJUMP which explored this area.

Russell Bay
Russell Bay (-73.45°N, -123.9°W) is a rather open bay in southwestern Amundsen Sea, extending along the north sides of Siple Island, Getz Ice Shelf and Carney Island, from Pranke Island to Cape Gates. It was mapped by the United States Geological Survey from surveys and USN air photos, 1959–66, and named by the Advisory Committee on Antarctic Names for Admiral James S. Russell, Vice Chief of Naval Operations during the post 1957–58 IGY period.