NASA - National Aeronautics and Space Administration

A gigantic cavity — two-thirds the area of Manhattan and almost 1,000 feet (300 meters) tall — growing at the bottom of Thwaites Glacier in West Antarctica is one of several disturbing discoveries reported in a new NASA-led study of the disintegrating glacier. The findings highlight the need for detailed observations of Antarctic glaciers' undersides in calculating how fast global sea levels will rise in response to climate change.