The Amundsen Sea, located off Marie Byrd Land in West Antarctica, is a significant body of water within the Southern Ocean. It has become a prominent focus for scientists worldwide. Its unique geographical characteristics and dynamic ice conditions make it a subject of extensive research, particularly concerning its environmental implications.
Geographical Context and Key Features
The Amundsen Sea is positioned south of approximately 70° S latitude. Its western boundary is marked by Cape Dart on Siple Island, while Cape Flying Fish at the northwestern edge of Thurston Island defines its eastern limit.
The Amundsen Sea has an average depth of about 585 meters. Water temperatures range from -1.1 to 1.7 °C (30 to 35 °F). The Amundsen Sea Embayment, an area of sea and glacial ice, drains into the sea. Two major ice shelves, the Thwaites and Pine Island Ice Shelves, border this sea.
The Melting Giant: Amundsen Sea’s Role in Sea Level Rise
The Amundsen Sea region contains some of the world’s most rapidly melting glaciers and ice sheets, including the Thwaites and Pine Island Glaciers. The Thwaites Glacier flows at over 4 kilometers per year and thins by almost 40 centimeters annually. This ice loss is driven by warm ocean currents, specifically modified Circumpolar Deep Water (mCDW), which erodes the undersides of the floating ice shelves.
The inflow of warm water beneath ice shelves causes basal melting, thinning the floating ice. This thinning can trigger marine ice sheet instability. The Amundsen Sea basin’s geology, with a retrograde slope where the bedrock deepens inland, makes it susceptible to rapid ice loss. As the ice thins and the grounding line—the point where the glacier lifts off the seabed—retreats, more of the ice sheet becomes exposed to warm ocean water, accelerating the melt. The meltwater from the Thwaites Glacier alone has contributed about 4 percent of recent global sea level rise, double its contribution from the mid-1990s.
Life Beneath the Ice: Unique Ecosystems
Despite its extreme conditions, the Amundsen Sea supports diverse marine life. Organisms such as krill, various fish species, seals, and whales inhabit these waters. These species have adapted to low temperatures and limited light. For example, some organisms can tolerate near-freezing water, while others rely on the rich food sources provided by the upwelling of nutrient-rich waters.
The Amundsen Sea is a significant feeding ground for many marine species. Diverse deep-sea invertebrates have also been observed; a 2008 expedition discovered thirty new marine species, including one feeding on octopus beak remains. This specialized ecosystem demonstrates life’s resilience in a challenging environment.
Why It Matters: Scientific Exploration and Global Impact
Extensive scientific research and expeditions are ongoing in the Amundsen Sea region, involving scientists globally. Researchers are focused on this area due to the rapid changes observed in its ice sheets and glaciers. Advanced technologies, such as autonomous underwater vehicles and satellite monitoring, are employed to gather data on ice thickness, ocean currents, and seabed topography.
Changes in the Amundsen Sea have far-reaching global implications. The substantial ice loss from this region directly contributes to global sea level rise, impacting coastal communities worldwide. Projections of future sea levels are heavily influenced by the observed melting rates in the Amundsen Sea. This region provides insights into broader global climate patterns and the future stability of polar ice.