A groundbreaking study led by the University of East Anglia in the UK has uncovered a significant process contributing to the melting of ice shelves in the Antarctic. The research, conducted by an international team of scientists, sheds light on how adjacent ice shelves play a crucial role in causing instability in others downstream.
The focus of the study was the Thwaites Ice Shelf, one of the largest ice shelves in West Antarctica, which supports the eastern side of the rapidly retreating Thwaites Glacier. The glacier is known as the largest contributor to global sea-level rise among Antarctic glaciers. Researchers utilized a unique dataset collected by sensors installed beneath the Thwaites Ice Shelf, which has experienced significant thinning and weakening in recent decades.
The findings reveal that the shallow layers of the ocean beneath the Thwaites Ice Shelf warmed considerably between January 2020 and March 2021. This warming was predominantly driven by glacial meltwater from the Pine Island Ice Shelf, located further east. When the ocean melts the base of ice shelves, the glacial meltwater mixes with saltwater, forming a buoyant layer of warmer water. This warmer water then melts the base of the Thwaites Ice Shelf.
Lead author Dr. Tiago Dotto emphasizes the importance of local ocean circulation and sea-ice in this process. He explains that while warm Antarctic waters, specifically the Circumpolar Deep Water, play a crucial role in melting ice shelves, the study highlights the significant impact of waters originating from nearby melting ice shelves. The heat exported from one ice shelf can reach the next through ocean circulation, thereby affecting the stability of adjacent ice shelves.
The researchers also identified the influence of a small ocean gyre, a system of circulating ocean currents, located next to the Thwaites Ice Shelf. A weaker gyre allows more warm water to access the areas beneath the ice shelf, intensifying the melting process. The study suggests that similar gyres in other regions around Antarctica could lead to a greater number of ice shelves being prone to intense basal melting and contribute further to global sea-level rise.
The study’s findings were supported by satellite images showing an unusual concentration of sea ice near the Thwaites Ice Shelf during the Southern Hemisphere summer season of 2020/2021. This indicated a weakened gyre, allowing excess meltwater from adjacent ice shelves to enter the Thwaites Ice Shelf.
Understanding the interconnectedness of ice shelves and the factors influencing their stability is vital in predicting future sea-level rise accurately. This research underscores the complex interactions between the atmosphere, sea ice, and ocean currents, highlighting the need for further study to develop comprehensive models of ice shelf behavior. With ongoing climate change, such knowledge is crucial for effective mitigation and adaptation strategies to combat the escalating threat of rising sea levels.