Ice is melting faster in Antarctica than expected - NASA scientists surprised

NASA scientists have discovered a huge cavity at the bottom of Thwaites glacier in West Antarctica, which is almost 300m tall. This indicates the rapid decay of ice sheets and acceleration in global sea levels - a consequence of the climate change. The discovery highlights the need of a detailed observation of the bottom of glaciers in Antarctica and calculate how fast sea levels will rise in response to the global warming.

Researchers were expecting gaps between ice and bedrocks at the bottom of the Thwaites glacier where ocean water could flow in and melt the glacier from below. However, they were surprised by the size and growth rate of this hole. It is estimated that the hole should have contained 14 billion tonnes of ice which should have melted over the last three years.
The giant cavity was revealed by the ice-penetrating radar in NASA's operation IceBridge. The researchers also used data from Italian and German space-borne synthetic aperture radars. A technique called radar interferometry was then used to process these high-resolution data to reveal how the surface below has moved.
The cavity under a glacier plays a major role in the melting process. As more heat and water get under the glacier, it melts faster - according to Pietro Milillo at JPL, NASA.
The Thwaites glacier is currently responsible for 4% of the overall rise in sea level. It holds the potential to rise the sea level upto 65 centimeters, whereas its neighbouring glaciers would raise it to 2.4 meters, if all the ice melts.
The Thwaites glacier is 160 km long and has been moving at the rate of 0.6 to 0.8 km per year since 1992. The huge cavity is under the main trunk of the glacier on its Western side, which is farther from Western Antarctic peninsula. Also, the melt rate on the side of the glacier is extremely high.