The 300-metre-tall gap can hold 14 billion Tonnes of ice:

• NASA scientists have discovered a gigantic cavity, almost 300 metres tall, growing at the bottom of the Thwaites Glacier in West Antarctica, indicating rapid decay of the ice sheet and acceleration in global sea levels due to climate change.
• The findings, published in the journal Science Advances, highlight the need for detailed observations of Antarctic glaciers’ undersides in calculating how fast sea levels will rise in response to warming.
• Researchers expected to find some gaps between ice and bedrock at Thwaites’ bottom, where ocean water could flow in and melt the glacier from below.
• The size and explosive growth rate of the hole, however, is surprised. It is big enough to have contained 14 billion tonnes of ice, and most of that ice melted over the last three years.It has been suspected for years that Thwaites was not tightly attached to the bedrock beneath. The cavity was revealed by ice-penetrating radar in NASA’s Operation Ice Bridge, an airborne campaign beginning in 2010 that studies connections between the polar regions and the global climate.