A series of six glaciers, including Pine Island and Thwaites Glaciers, hold back ice streams of the West Antarctic from flowing into the ocean. Thwaites is the largest of these glaciers that serve as barriers. If Thwaites melted entirely, then global sea levels would rise about 2 feet. But if the shrinkage of Thwaites led to the collapse of the entire West Antarctic Ice Shelf, then the ice streams would flow into the ocean and sea levels might rise as high as 16 feet.
