Thwaites glacier in West Antarctica are enormous in size and often referred to as the most dangerous glacier on Earth. The glacier holds two feet of sea level but more importantly, it is the "backstop" for four other glaciers which holds an additional 10 to 13 feet of sea level rise. If Thwaites collapses, it will take most of West Antarctica with it.
According to researchers at the University of Washington in 2014, Thwaites is already collapsing. "The simulations indicate that early-stage collapse has begun," notes their paper. What's more, the Thwaites Glacier is a "linchpin" for the rest of the West Antarctic Ice Sheet; its rapid collapse would "probably spill over to adjacent catchments, undermining much of West Antarctica."
In January, NASA's Jet Propulsion Laboratory revealed there is a massive cavity carved in the underbelly of the glacier due to ocean warming. This raises alarms as the chunk of ice could collapse and disintegrate the ice shelf. Researchers in the study found that the cavity is said to be two-thirds of the area of Manhattan and almost 300 meters tall. The cavity used to held fourteen billion tons of ice, however, within just three short years the ice melted away. It was NASA's Icebridge program that made the discovery using ice-penetrating radar through the miles' deep glacier as well as "data from a constellation of Italian and German spaceborne synthetic aperture radars". But that was just one of the terrors that the satellites found, it confirmed fears that Thwaites was not attached to the bedrock.
Another changing feature is a glacier's grounding line, the place near the edge of the continent where it lifts off its bed and starts to float on seawater. Many Antarctic glaciers extend for miles beyond their grounding lines, floating out over the open ocean. Just as a grounded boat can float again when the weight of its cargo is removed, a glacier that loses ice weight can float over land where it used to stick. When this happens, the grounding line retreats inland. That exposes more of a glacier's underside to seawater, accelerating the melt rate.
Thwaites is like the cork in the wine bottle for the rest of the West Antarctica ice sheet. If thwaites were to fall apart, scientists fear the entire ice sheet could begin to collapse, eventually raising sea levels more than 10 feet.
